Search results for: rotating bending fatigue

Authors: Jiri Cecrdle

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This paper describes the concept of the W-WING whirl flutter aeroelastic demonstrator. Whirl flutter is the specific case of flutter that accounts for the additional dynamic and aerodynamic influences of the engine rotating parts. The instability is driven by motion-induced unsteady aerodynamic propeller forces and moments acting in the propeller plane. Whirl flutter instability is a serious problem that may cause the unstable vibration of a propeller mounting, leading to the failure of an engine installation or an entire wing. The complicated physical principle of whirl flutter required the experimental validation of the analytically gained results. W-WING aeroelastic demonstrator has been designed and developed at Czech Aerospace Research Centre (VZLU) Prague, Czechia. The demonstrator represents the wing and engine of the twin turboprop commuter aircraft. Contrary to the most of past demonstrators, it includes a powered motor and thrusting propeller. It allows the changes of the main structural parameters influencing the whirl flutter stability characteristics. Propeller blades are adjustable at standstill. The demonstrator is instrumented by strain gauges, accelerometers, revolution-counting impulse sensor, sensor of airflow velocity, and the thrust measurement unit. Measurement is supported by the in house program providing the data storage and real-time depiction in the time domain as well as pre-processing into the form of the power spectral densities. The engine is linked with a servo-drive unit, which enables maintaining of the propeller revolutions (constant or controlled rate ramp) and monitoring of immediate revolutions and power. Furthermore, the program manages the aerodynamic excitation of the demonstrator by the aileron flapping (constant, sweep, impulse). Finally, it provides the safety guard to prevent any structural failure of the demonstrator hardware. In addition, LMS TestLab system is used for the measurement of the structure response and for the data assessment by means of the FFT- and OMA-based methods. The demonstrator is intended for the experimental investigations in the VZLU 3m-diameter low-speed wind tunnel. The measurement variant of the model is defined by the structural parameters: pitch and yaw attachment stiffness, pitch and yaw hinge stations, balance weight station, propeller type (duralumin or steel blades), and finally, angle of attack of the propeller blade 75% section (). The excitation is provided either by the airflow turbulence or by means of the aerodynamic excitation by the aileron flapping using a frequency harmonic sweep. The experimental results are planned to be utilized for validation of analytical methods and software tools in the frame of development of the new complex multi-blade twin-rotor propulsion system for the new generation regional aircraft. Experimental campaigns will include measurements of aerodynamic derivatives and measurements of stability boundaries for various configurations of the demonstrator.

Keywords: aeroelasticity, flutter, whirl flutter, W WING demonstrator

Procedia PDF Downloads 87

Authors: D. Supaporn, B. Julaluk

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The purposes of this study were to study symptom cluster, functional status and quality of life of patients with chronic obstructive pulmonary disease (COPD), and to examine factors related to and predicting symptom cluster, functional status and quality of life of COPD patients. The sample was 180 COPD patients multi-stage random sampling from 4 hospitals in the eastern region, Thailand. The research instruments were 8 questionnaires and recorded forms measuring personal and illness data, co-morbidity, physical and psychological symptom, health status perception, social support, and regimen adherence, functional status and quality of life. Spearman rank and Pearson correlation coefficient, exploratory factors analysis and standard multiple regression were used to analyzed data. The findings revealed that two symptom clusters were generated: physical symptom cluster including dyspnea, fatigue and insomnia; and, psychological symptom cluster including anxiety and depression. Scores of physical symptom cluster was at moderate level while that of psychological symptom cluster was at low level. Scores on functional status, social support and overall regimen adherence were at good level whereas scores on quality of life and health status perception were at moderate level. Disease severity was positively related to physical symptom cluster, psychological symptom cluster and quality of life, and was negatively related to functional status at a moderate level (rs = .512, .509, .588 and -.611, respectively). Co-morbidity was positively related to physical symptom cluster and psychological symptom cluster at a low level (r = .179 and .176, respectively). Regimen adherence was negatively related to quality of life and psychological symptom cluster at a low level (r=-.277 and -.309, respectively), and was positively related to functional status at a moderate level (r=.331). Health status perception was negatively related to physical symptom cluster, psychological symptom cluster and quality of life at a moderate to high level (r = -.567, -.640 and -.721, respectively) and was positively related to functional status at a high level (r = .732). Social support was positively related to functional status (r=.235) and was negatively related to quality of life at a low level (r=-.178). Physical symptom cluster was negatively related to functional status (r= -.490) and was positively related to quality of life at a moderate level (r=.566). Psychological symptom cluster was negatively related to functional status and was positively related to quality of life at a moderate level (r= -.566 and .559, respectively). Disease severity, co-morbidity and health status perception could predict 40.2% of the variance of physical symptom cluster. Disease severity, co-morbidity, regimen adherence and health status perception could predict 49.8% of the variance of psychological symptom cluster. Co-morbidity, regimen adherence and health status perception could predict 65.0% of the variance of functional status. Disease severity, health status perception and physical symptom cluster could predict 60.0% of the variance of quality of life in COPD patients. The results of this study can be used for enhancing quality of life of COPD patients.

Keywords: chronic obstructive pulmonary disease, functional status, quality of life, symptom cluster

Procedia PDF Downloads 551

Authors: Maciej Szelag

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The discovery of the carbon nanotubes (CNT), has led to a breakthrough in the material engineering. The CNT is characterized by very large surface area, very high Young's modulus (about 2 TPa), unmatched durability, high tensile strength (about 50 GPa) and bending strength. Their diameter usually oscillates in the range from 1 to 100 nm, and the length from 10 nm to 10-2 m. The relatively new approach is the CNT’s application in the concrete technology. The biggest problem in the use of the CNT to cement composites is their uneven dispersion and low adhesion to the cement paste. Putting the nanotubes alone into the cement matrix does not produce any effect because they tend to agglomerate, due to their large surface area. Most often, the CNT is used as an aqueous suspension in the presence of a surfactant that has previously been sonicated. The paper presents the results of investigations of the basic physical properties (apparent density, shrinkage) and mechanical properties (compression and tensile strength) of cement paste with the addition of the multiwall carbon nanotubes (MWCNT). The studies were carried out on four series of specimens (made of two different Portland Cement). Within each series, samples were made with three w/c ratios – 0.4, 0.5, 0.6 (water/cement). Two series were an unmodified cement matrix. In the remaining two series, the MWCNT was added in amount of 0.1% by cement’s weight. The MWCNT was used as an aqueous dispersion in the presence of a surfactant – SDS – sodium dodecyl sulfate (C₁₂H₂₅OSO₂ONa). So prepared aqueous solution was sonicated for 30 minutes. Then the MWCNT aqueous dispersion and cement were mixed using a mechanical stirrer. The parameters were tested after 28 days of maturation. Additionally, the change of these parameters was determined after samples temperature loading at 250°C for 4 hours (thermal shock). Measurement of the apparent density indicated that cement paste with the MWCNT addition was about 30% lighter than conventional cement matrix. This is due to the fact that the use of the MWCNT water dispersion in the presence of surfactant in the form of SDS resulted in the formation of air pores, which were trapped in the volume of the material. SDS as an anionic surfactant exhibits characteristics specific to blowing agents – gaseous and foaming substances. Because of the increased porosity of the cement paste with the MWCNT, they have obtained lower compressive and tensile strengths compared to the cement paste without additive. It has been observed, however, that the smallest decreases in the compressive and tensile strength after exposure to the elevated temperature achieved samples with the MWCNT. The MWCNT (well dispersed in the cement matrix) can form bridges between hydrates in a nanoscale of the material’s structure. Thus, this may result in an increase in the coherent cohesion of the cement material subjected to a thermal shock. The obtained material could be used for the production of an aerated concrete or using lightweight aggregates for the production of a lightweight concrete.

Keywords: cement paste, elevated temperature, mechanical parameters, multiwall carbon nanotubes, physical parameters, SDS

Procedia PDF Downloads 348

Authors: Muhammad Bilal, Amelia Jane Llyod, Habsah Mohamad, Jia Hui Wong, Abdul Aziz Mohamed Yusoff, Jafri Malin Abdullah, Jingli Zhang

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Epilepsy is one of the major brain afflictions occurs with uncontrolled excitation of cortex; disturbed 50 million of world’s population. About 25 percent of patients subjected to adverse effects from antiepileptic drugs (AEDs) such as depression, nausea, tremors, gastrointestinal symptoms, osteoporosis, dizziness, weight change, drowsiness, fatigue are commonly observed indications; therefore, new drugs are required to cure epilepsy. GABA is principle inhibitory neurotransmitter, control excitation of the brain. Mutation or dysfunction of GABA receptor is one of the primary causes of epilepsy, which is confirmed from many acquired models of epilepsy like traumatic brain injury, kindling, and status epilepticus models of epilepsy. GABA receptor has 3 distinct types such as GABA (A), GABA (B), GABA(C).GABA (A) receptor has 20 different subunits, α1β2γ2 subunits composition of GABA (A) receptor is the most used combination of subunits for screening of compounds against epilepsy. We expressed α1β2γ2s subunits of GABA (A) Receptor in Xenopus leavis oocytes and examined the enhancement potential of 4-Hydroxybenzoic acid compound on GABA (A) receptor via two-electrode voltage clamp current recording technique. Bamboo shoots are the young, tender offspring of bamboo, which are usually harvested after a cultivating period of 2 weeks. Proteins, acids, fat, starch, carbohydrate, fatty acid, vitamin, dietary fiber, and minerals are the major constituent found systematically in bamboo shoots. These shoots reported to have anticancer, antiviral, antibacterial activity, also possess antioxidant properties due to the presence of phenolic compounds. Student t-test analysis suggested that 4- hydroxybenzoic acid positively allosteric GABA (A) receptor, increased normalized current amplitude to 1.0304±0.0464(p value 0.032) compared with vehicle. 4-Hydrobenzoic acid, a compound from Dendrocalamus Asper bamboo shoot gives new insights for future studies on bamboo shoots with motivation for extraction of more compounds to investigate their effects on human and rodents against epilepsy, insomnia, and anxiety.

Keywords: α1β2γ2S, antiepileptic, bamboo shoots, epilepsy GABA (A) receptor, two-microelectrode voltage clamp, xenopus laevis oocytes

Procedia PDF Downloads 396

Authors: B. Mohammadi, A. Riazati, P. Soltan Sanjari, S. Azimbeik

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The ever-increasing development of civic demands on one hand; and the urban constrains for newly establish of infrastructures, on the other hand, perforce the engineering committees to apply non-conflicting methods in order to optimize the results. One of these optimized procedures to establish the main sewerage networks is the pipe jacking and micro-tunneling method. The raw information and researches are based on the experiments of the slurry micro-tunneling project of the Tehran main sewerage network that it has executed by the KAYSON co. The 4985 meters route of the mentioned project that is located nearby the Azadi square and the most vital arteries of Tehran is faced to 45% physical progress nowadays. The boring machine is made by the Herrenknecht and the diameter of the using concrete-polymer pipes are 1600 and 1800 millimeters. Placing and excavating several shafts on the ground and direct Tunnel boring between the axes of issued shafts is one of the requirements of the micro-tunneling. Considering the stream of the ground located shafts should care the hydraulic circumstances, civic conditions, site geography, traffic cautions and etc. The profile length has to convert to many shortened segment lines so the generated angle between the segments will be based in the manhole centers. Each segment line between two continues drive and receive the shaft, displays the jack location, driving angle and the path straight, thus, the diversity of issued angle causes the variety of jack positioning in the shaft. The jacking frame fixing conditions and it's associated dynamic load direction produces various patterns of Stress and Strain distribution and creating fatigues in the shaft wall and the soil surrounded the shaft. This pattern diversification makes the shaft wall transformed, unbalanced subsidence and alteration in the pipe jacking Stress Contour. This research is based on experiments of the Tehran's west sewerage plan and the numerical analysis the interaction of the soil around the shaft, shaft walls and the Jacking frame direction and finally, the suitable or unsuitable location of the pipe jacking shaft will be determined.

Keywords: underground structure, micro-tunneling, fatigue analysis, dynamic-soil–structure interaction, underground water, finite element analysis

Procedia PDF Downloads 312

Authors: Desmond Appiah, Fan Zhang, Shouqi Yuan, Wei Xueyuan, Stephen N. Asomani

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The side channel pump has distinctive hydraulic performance characteristics over other vane pumps because of its generation of high pressure heads in only one impeller revolution. Hence, there is soaring utilization and application in the fields of petrochemical, food processing fields, automotive and aerospace fuel pumping where high heads are required at low flows. The side channel pump is characterized by unstable flow because after fluid flows into the impeller passage, it moves into the side channel and comes back to the impeller again and then moves to the next circulation. Consequently, the flow leaves the side channel pump following a helical path. However, the pressure fluctuation exhibited in the flow greatly contributes to the unwanted noise and vibration which is associated with the flow. In this paper, a side channel pump prototype was examined thoroughly through numerical calculations based on SST k-ω turbulence model to ascertain the pressure fluctuation behavior. The pressure fluctuation intensity of the 3D unstable flow dynamics were carefully investigated under different working conditions 0.8QBEP, 1.0 QBEP and 1.2QBEP. The results showed that the pressure fluctuation distribution around the pressure side of the blade is greater than the suction side at the impeller and side channel interface (z=0) for all three operating conditions. Part-load condition 0.8QBEP recorded the highest pressure fluctuation distribution because of the high circulation velocity thus causing an intense exchanged flow between the impeller and side channel. Time and frequency domains spectra of the pressure fluctuation patterns in the impeller and the side channel were also analyzed under the best efficiency point value, QBEP using the solution from the numerical calculations. It was observed from the time-domain analysis that the pressure fluctuation characteristics in the impeller flow passage increased steadily until the flow reached the interrupter which separates low-pressure at the inflow from high pressure at the outflow. The pressure fluctuation amplitudes in the frequency domain spectrum at the different monitoring points depicted a gentle decreasing trend of the pressure amplitudes which was common among the operating conditions. The frequency domain also revealed that the main excitation frequencies occurred at 600Hz, 1200Hz, and 1800Hz and continued in the integers of the rotating shaft frequency. Also, the mass flow exchange plots indicated that the side channel pump is characterized with many vortex flows. Operating conditions 0.8QBEP, 1.0 QBEP depicted less and similar vortex flow while 1.2Q recorded many vortex flows around the inflow, middle and outflow regions. The results of the numerical calculations were finally verified experimentally. The performance characteristics curves from the simulated results showed that 0.8QBEP working condition recorded a head increase of 43.03% and efficiency decrease of 6.73% compared to 1.0QBEP. It can be concluded that for industrial applications where the high heads are mostly required, the side channel pump can be designed to operate at part-load conditions. This paper can serve as a source of information in order to optimize a reliable performance and widen the applications of the side channel pumps.

Keywords: exchanged flow, pressure fluctuation, numerical simulation, side channel pump

Procedia PDF Downloads 132

Authors: A. J. Cobley, L. Krishnan

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The demand for multi-functional lightweight materials in sectors such as automotive, aerospace, electronics is growing, and for this reason fibre-reinforced, epoxy polymer composites are being widely utilized. The fibre reinforcing material is mainly responsible for the strength and stiffness of the composites whilst the main role of the epoxy polymer matrix is to enhance the load distribution applied on the fibres as well as to protect the fibres from the effect of harmful environmental conditions. The superior properties of the fibre-reinforced composites are achieved by the best properties of both of the constituents. Although factors such as the chemical nature of the epoxy and how it is cured will have a strong influence on the properties of the epoxy matrix, the method of mixing and degassing of the resin can also have a significant impact. The production of a fibre-reinforced epoxy polymer composite will usually begin with the mixing of the epoxy pre-polymer with a hardener and accelerator. Mechanical methods of mixing are often employed for this stage but such processes naturally introduce air into the mixture, which, if it becomes entrapped, will lead to voids in the subsequent cured polymer. Therefore, degassing is normally utilised after mixing and this is often achieved by placing the epoxy resin mixture in a vacuum chamber. Although this is reasonably effective, it is another process stage and if a method of mixing could be found that, at the same time, degassed the resin mixture this would lead to shorter production times, more effective degassing and less voids in the final polymer. In this study the effect of four different methods for mixing and degassing of the pre-polymer with hardener and accelerator were investigated. The first two methods were manual stirring and magnetic stirring which were both followed by vacuum degassing. The other two techniques were ultrasonic mixing/degassing using a 40 kHz ultrasonic bath and a 20 kHz ultrasonic probe. The cured cast resin samples were examined under scanning electron microscope (SEM), optical microscope, and Image J analysis software to study morphological changes, void content and void distribution. Three point bending test and differential scanning calorimetry (DSC) were also performed to determine the thermal and mechanical properties of the cured resin. It was found that the use of the 20 kHz ultrasonic probe for mixing/degassing gave the lowest percentage voids of all the mixing methods in the study. In addition, the percentage voids found when employing a 40 kHz ultrasonic bath to mix/degas the epoxy polymer mixture was only slightly higher than when magnetic stirrer mixing followed by vacuum degassing was utilized. The effect of ultrasonic mixing/degassing on the thermal and mechanical properties of the cured resin will also be reported. The results suggest that low frequency ultrasound is an effective means of mixing/degassing a pre-polymer mixture and could enable a significant reduction in production times.

Keywords: degassing, low frequency ultrasound, polymer composites, voids

Procedia PDF Downloads 294

Authors: T. Kuchukhidze, N. Jalagonia, T. Archuadze, G. Bokuchava

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The growing scientific-technological progress in modern civilization causes actuality of producing construction materials which can successfully work in conditions of high temperature, radiation, pressure, speed, and chemically aggressive environment. Such extreme conditions can withstand very few types of materials and among them, ceramic materials are in the first place. Corundum ceramics is the most useful material for creation of constructive nodes and products of various purposes for its low cost, easy accessibility to raw materials and good combination of physical-chemical properties. However, ceramic composite materials have one disadvantage; they are less plastics and have lower toughness. In order to increase the plasticity, the ceramics are reinforced by various dopants, that reduces the growth of the cracks. It is shown, that adding of even small amount of carbon fibers and carbon nanotubes (CNT) as reinforcing material significantly improves mechanical properties of the products, keeping at the same time advantages of alundum ceramics. Graphene in composite material acts in the same way as inorganic dopants (MgO, ZrO2, SiC and others) and performs the role of aluminum oxide inhibitor, as it creates shell, that gives possibility to reduce sintering temperature and at the same time it acts as damper, because scattering of a shock wave takes place on carbon structures. Application of different structural modification of carbon (graphene, nanotube and others) as reinforced material, gives possibility to create multi-purpose highly requested composite materials based on alundum ceramics. In the present work offers simplified technology for obtaining of aluminum oxide ceramics, reinforced with carbon nanostructures, during which chemical modification with doping carbon nanostructures will be implemented in the process of synthesis of final powdery composite – Alumina. In charge doping carbon nanostructures connected to matrix substance with C-O-Al bonds, that provide their homogeneous spatial distribution. In ceramic obtained as a result of consolidation of such powders carbon fragments equally distributed in the entire matrix of aluminum oxide, that cause increase of bending strength and crack-resistance. The proposed way to prepare the charge simplifies the technological process, decreases energy consumption, synthesis duration and therefore requires less financial expenses. In the implementation of this work, modern instrumental methods were used: electronic and optical microscopy, X-ray structural and granulometric analysis, UV, IR, and Raman spectroscopy.

Keywords: ceramic materials, α-Al₂O₃, carbon nanostructures, composites, characterization, hot-pressing

Procedia PDF Downloads 116

Authors: Fang Li, Jiazhao Wang, Jianmin Ma

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The practical application of Li-S batteries is hampered due to poor cycling stability caused by electrolyte-dissolved lithium polysulfides. Dual functionalities such as strong chemical adsorption stability and high conductivity are highly desired for an ideal host material for a sulfur-based cathode. Polypyrrole (PPy), as a conductive polymer, was widely studied as matrixes for sulfur cathode due to its high conductivity and strong chemical interaction with soluble polysulfides. Thus, a novel cathode structure consisting of a free-standing sulfur-polypyrrole cathode and a polypyrrole coated separator was designed for flexible Li-S batteries. The PPy materials show strong interaction with dissoluble polysulfides, which could suppress the shuttle effect and improve the cycling stability. In addition, the synthesized PPy film with a rough surface acts as a current collector, which improves the adhesion of sulfur materials and restrain the volume expansion, enhancing the structural stability during the cycling process. For further enhancing the cycling stability, a PPy coated separator was also applied, which could make polysulfides into the cathode side to alleviate the shuttle effect. Moreover, the PPy layer coated on commercial separator is much lighter than other reported interlayers. A soft-packaged flexible Li-S battery has been designed and fabricated for testing the practical application of the designed cathode and separator, which could power a device consisting of 24 light-emitting diode (LED) lights. Moreover, the soft-packaged flexible battery can still show relatively stable cycling performance after repeated bending, indicating the potential application in flexible batteries. A novel vapor phase deposition method was also applied to prepare uniform polypyrrole layer coated sulfur/graphene aerogel composite. The polypyrrole layer simultaneously acts as host and adsorbent for efficient suppression of polysulfides dissolution through strong chemical interaction. The density functional theory (DFT) calculations reveal that the polypyrrole could trap lithium polysulfides through stronger bonding energy. In addition, the deflation of sulfur/graphene hydrogel during the vapor phase deposition process enhances the contact of sulfur with matrixes, resulting in high sulfur utilization and good rate capability. As a result, the synthesized polypyrrole coated sulfur/graphene aerogel composite delivers a specific discharge capacity of 1167 mAh g⁻¹ and 409.1 mAh g⁻¹ at 0.2 C and 5 C respectively. The capacity can maintain at 698 mAh g⁻¹ at 0.5 C after 500 cycles, showing an ultra-slow decay rate of 0.03% per cycle.

Keywords: polypyrrole, strong chemical interaction, long-term stability, Li-S batteries

Procedia PDF Downloads 135

Authors: Corbel Camille, Le Cerf Flora, Capriz Françoise, Vaillant-Ciszewicz Anne-Julie, Breaud Jean, Guerin Olivier, Corveleyn Xavier

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Background: The medical environment can generate stressful and anxiety-provoking situations for patients, particularly during painful care procedures for the older population. These stressful environments have deleterious effects on the quality of care and can even put the patient at risk and set the care team up for failure. The search for a solution is, therefore, imperative. The development of new technologies, such as virtual reality (VR), seems to be an answer to this problem. Objectives: The objective of this study is to compare the effects of virtual reality on pain and anxiety when caring for older hospitalized people with the effects of usual care. More precisely, different individual factors (age, cognitive level, individual preferences, etc.) and different virtual reality universes (personalized or non-personalized) are studied to understand the role of these factors in reducing pain and anxiety during care procedures. The aim of this study is to improve the quality of life of patients and caregivers in their work environment. Method: This mono-centered, randomized, controlled study was conducted from September 2023 to September 2024 on 120 participants recruited from the geriatric departments of the Cimiez Hospital, Nice, France. Participants are randomized into three groups: a control group, a personalized VR group and a non-personalized VR group. Each participant is followed during a painful care session. Data are collected before, during and after the care, using measures of pain (Algoplus and numerical scale) and anxiety (Hospital anxiety scale and numerical scale). Physiological assessments with an oximeter are also performed to collect both heart and respiratory rate measurements. The implementation of the care will be assessed among healthcare providers to evaluate its effects on the difficulty and fatigue associated with the care. Additionally, a questionnaire (System Usability Scale) will be administered at the conclusion of the study to determine the willingness of healthcare providers to integrate VR into their daily care practices. Result: The preliminary results indicate significant effects on anxiety (p=.001) and pain (p=<.001) following the VR intervention during care, as compared to the control group. Conclusion: The preliminary results suggest that VRI appears to be a suitable and effective method for reducing anxiety and pain among older hospitalized individuals compared with standard care. Finally, the experiences of healthcare professionals involved will also be considered to assess the impact of these interventions on working conditions and patient support.

Keywords: anxiety, care, pain, older adults, virtual reality

Procedia PDF Downloads 64

Authors: Anna Martin, Raffael Osen

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The demand for fish from aquaculture is constantly growing. Concurrently, due to a shortage of fishmeal caused by extensive overfishing, fishmeal substitution by plant proteins is getting increasingly important for the production of sustainable aquafeed. Several research studies evaluated the impact of plant protein meals, concentrates or isolates on fish health and fish feed quality. However, these protein raw materials often require elaborate and expensive manufacturing and their availability is limited. Rapeseed press cake (RPC) – a side product of de-oiling processes – exhibits a high potential as a plant-based fishmeal alternative in fish feed for carnivorous species due to its availability, low costs and protein content. In order to produce aquafeed with RPC, it is important to systematically assess i) inclusion levels of RPC with similar pellet qualities compared to fishmeal containing formulations and ii) how extrusion parameters can be adjusted to achieve targeted pellet qualities. However, the effect of RPC on extrusion system parameters and pellet quality has only scarcely been investigated. Therefore, the aim of this study was to evaluate the impact of feed formulation, extruder barrel temperature (90, 100, 110 °C) and screw speed (200, 300, 400 rpm) on extrusion system parameters and the physical properties of fish feed pellets. A co-rotating pilot-scale twin screw extruder was used to produce five iso-nitrogenous feed formulations: a fish meal based reference formulation including 16 g/100g fishmeal and four formulations in which fishmeal was substituted by RPC to 25, 50, 75 or 100 %. Extrusion system parameters, being product temperature, pressure at the die, specific mechanical energy (SME) and torque, were monitored while samples were taken. After drying, pellets were analyzed regarding to optical appearance, sectional and longitudinal expansion, sinking velocity, bulk density, water stability, durability and specific hardness. In our study, the addition of minor amounts of RPC already had high impact on pellet quality parameters, especially on expansion but only marginally affected extrusion system parameters. Increasing amounts of RPC reduced sectional expansion, sinking velocity, bulk density and specific hardness and increased longitudinal expansion compared to a reference formulation without RPC. Water stability and durability were almost not affected by RPC addition. Moreover, pellets with rapeseed components showed a more coarse structure than pellets containing only fishmeal. When the adjustment of barrel temperature and screw speed was investigated, it could be seen that the increase of extruder barrel temperature led to a slight decrease of SME and die pressure and an increased sectional expansion of the reference pellets but did almost not affect rapeseed containing fish feed pellets. Also changes in screw speed had little effects on the physical properties of pellets however with raised screw speed the SME and the product temperature increased. In summary, a one-to-one substitution of fishmeal with RPC without the adjustment of extrusion process parameters does not result in fish feed of a designated quality. Therefore, a deeper knowledge of raw materials and their behavior under thermal and mechanical stresses as applied during extrusion is required.

Keywords: extrusion, fish feed, press cake, rapeseed

Procedia PDF Downloads 139

Authors: Babarina Maria, Andropova Margarita

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Introduction: Hypoparathyroidism (HypoPT) is a rare endocrine disorder with an estimated prevalence of 0.25 per 1000 individuals. The most common cause of HypoPT is the loss of active parathyroid tissue following thyroid or parathyroid surgery. Sometimes permanent postoperative HypoPT occures, manifested by hypocalcemia in combination with low levels of PTH during 6 months or more after surgery. Cognitive impairments in patients with hypocalcemia due to chronic HypoPT are observed, and this can lead to problems and challenges in everyday living: memory loss and impaired concentration, that may be the cause of poor compliance. Clinical case: Patient K., 66 years old, underwent thyroidectomy in 2013 (at the age of 55) because of papillary thyroid cancer T1NxMx, histopathology findings confirmed the diagnosis. 5 years after the surgery, she was followed up on an outpatient basis, TSH levelsonly were monitored, and the dose of levothyroxine was adjusted. In 2018 due to, increasing complaints include tingling and cramps in the arms and legs, memory loss, sleep disorder, fatigue, anxiety, hair loss, muscle pain, tachycardia, positive Chvostek, and Trousseau signs were diagnosed during examination, also in blood analyses: total Ca 1.86 mmol/l (2.15-2.55), Ca++ 0.96 mmol/l (1.12-1.3), P 1.55 mmol/l (0.74-1.52), Mg 0.79 mmol/l (0.66-1.07) - chronic postoperative HypoPT was diagnosed. Therapy was initiated: alfacalcidol 0.5 mcg per day, calcium carbonate 2000 mg per day, cholecalciferol 1000 IU per day, magnesium orotate 3000 mg per day. During the case follow-up, hypocalcemia, hyperphosphatemia persisted, hypercalciuria15.7 mmol/day (2.5-6.5) was diagnosed. Dietary recommendations were given because of the high content of phosphorus rich foods, and therapy was adjusted: the dose of alfacalcidol was increased to 2.5 mcg per day, and the dose of calcium carbonate was reduced to 1500 mg per day. As part of the screening for complications of hypoPT, data for cataracts, Fahr syndrome, nephrocalcinosis, and kidney stone disease were not obtained. However, HypoPT compensation was not achieved, and therefore hydrochlorothiazide 25 mg was initiated, the dose of alfacalcidol was increased to 3 mcg per day, calcium carbonate to 3000 mg per day, magnesium orotate and cholecalciferol were continued at the same doses. Therapeutic goals were achieved: calcium phosphate product <4.4 mmol2/l2, there were no episodes of hypercalcemia, twenty-four-hour urinary calcium excretion was significantly reduced. Conclusion: Timely prescription, careful explanation of drugs usage rules, and monitoring and maintaining blood and urine parameters within the target contribute to the prevention of HypoPT complications development and life-threatening events.

Keywords: hypoparathyroidism, hypocalcemia, hyperphosphatemia, hypercalciuria

Procedia PDF Downloads 99

Authors: Marielle Hanley, Brandon Takahashi, Gerry Hanley, Gabriella Hancock

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Safety harnesses and their protocols are very common within the construction industry, and the Occupational Safety and Health Administration has provided extensive guidelines with protocols being constantly updated to ensure the highest level of safety within construction sites. There is also extensive research on harnesses that are meant to keep people in place in moving vehicles, such as seatbelts. Though this research is comprehensive in these areas, the findings and recommendations are not generally applicable to other industry sectors where harnesses are used, such as the entertainment industry. The focus of this case study is on the design and use of harnesses used by theme park employees wearing elaborate costumes in parades and performances. The key factors of posture, kinesthetic factors, and harness engineering interact in significantly different ways when the user is performing repetitive choreography with 20 to 40 lbs. of apparatus connected to harnesses that need to be hidden from the audience’s view. Human factors and ergonomic analysis take into account the required performers’ behaviors, the physical and mental preparation and posture of the performer, the design of the harness-embedded costume, and the environmental conditions during the performance (e.g., wind) that can determine the physical stresses placed on the harness and performer. The uniqueness and expense of elaborate costumes frequently result in one or two costumes created for production, and a variety of different performers need to fit into the same costume. Consequently, the harnesses should be adjustable if they are to minimize the physical and cognitive loads on the performer, but they are frequently more a “one-size fits all”. The complexity of human and technology interactions produces a range of detrimental outcomes, from muscle strains to nerve damage, mental and physical fatigue, and reduced motivation to perform at peak levels. Based on observations conducted over four years for this case study, a number of recommendations to institutionalize the human factors and ergonomic analyses can significantly improve the safety, reliability, and quality of performances with harness-embedded costumes in the entertainment industry. Human factors and ergonomic analyses can be integrated into the engineering design of the performance costumes with embedded harnesses, the conditioning and training of the performers using the costumes, the choreography of the performances within the staged setting and the maintenance of the harness-embedded costumes. By applying human factors and ergonomic methodologies in the entertainment industry, the industry management and support staff can significantly reduce the risks of injury, improve the longevity of unique performers, increase the longevity of the harness-embedded costumes, and produce the desired entertainment value for audiences.

Keywords: ergonomics in entertainment industry, harness-embedded costumes, performer safety, injury prevention

Procedia PDF Downloads 81

Authors: Kumaran Letchmanan, Shou-Cang Shen, Wai Kiong Ng

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Postoperative implant-associated infections in soft tissues and bones remain a serious complication in orthopaedic surgery, which leads to impaired healing, re-implantation, prolong hospital stay and increase cost. Drug-loaded implants with sustained release of antibiotics at the local site are current research interest to reduce the risk of post-operative infections and osteomyelitis, thus, minimize the need for follow-up care and increase patient comfort. However, the improved drug release of the drug-loaded bone cements is usually accompanied by a loss in mechanical strength, which is critical for weight-bearing bone cement. Recently, more attempts have been undertaken to develop techniques to enhance the antibiotic elution as well as preserve the mechanical properties of the bone cements. The present study investigates the potential influence of addition of mesoporous silica nanoparticles (MSN) on the in vitro drug release kinetics of gentamicin (GTMC), along with the mechanical properties of bone cements. Simplex P was formulated with MSN and loaded with GTMC by direct impregnation. Meanwhile, Simplex P with water soluble poragen (xylitol) and high loading of GTMC as well as commercial bone cement CMW Smartset GHV were used as controls. MSN-formulated bone cements are able to increase the drug release of GTMC by 3-fold with a cumulative release of more than 46% as compared with other control groups. Furthermore, a sustained release could be achieved for two months. The loaded nano-sized MSN with uniform pore channels significantly build up an effective nano-network path in the bone cement facilitates the diffusion and extended release of GTMC. Compared with formulations using xylitol and high GTMC loading, incorporation of MSN shows no detrimental effect on biomechanical properties of the bone cements as no significant changes in the mechanical properties as compared with original bone cement. After drug release for two months, the bending modulus of MSN-formulated bone cements is 4.49 ± 0.75 GPa and the compression strength is 92.7 ± 2.1 MPa (similar to the compression strength of Simplex-P: 93.0 ± 1.2 MPa). The unaffected mechanical properties of MSN-formulated bone cements was due to the unchanged microstructures of bone cement, whereby more than 98% of MSN remains in the matrix and supports the bone cement structures. In contrast, the large portions of extra voids can be observed for the formulations using xylitol and high drug loading after the drug release study, thus caused compressive strength below the ASTM F541 and ISO 5833 minimum of 70 MPa. These results demonstrate the potential applicability of MSN-functionalized poly(methyl methacrylate)-based bone cement as a highly efficient, sustained and local drug delivery system with good mechanical properties.

Keywords: antibiotics, biomechanical properties, bone cement, sustained release

Procedia PDF Downloads 254

Authors: Zuyong Chen, Jianghao Wu, Yanlai Zhang

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Flapping-wing micro aerial vehicle (FMAV) is a new type of aircraft by mimicking the flying behavior to that of small birds or insects. Comparing to the traditional fixed wing or rotor-type aircraft, FMAV only needs to control the motion of flapping wings, by changing the size and direction of lift to control the flight attitude. Therefore, its transmission system should be designed very compact. Lightweight design can effectively extend its endurance time, while engineering experience alone is difficult to simultaneously meet the requirements of FMAV for structural strength and quality. Current researches still lack the guidance of considering nonlinear factors of 3D printing material when carrying out topology optimization, especially for the tiny FMAV transmission system. The coupling of non-linear material properties and non-linear contact behaviors of FMAV transmission system is a great challenge to the reliability of the topology optimization result. In this paper, topology optimization design based on FEA solver package Altair Optistruct for the transmission system of FMAV manufactured by 3D Printing was carried out. Firstly, the isotropic constitutive behavior of the Ultraviolet (UV) Cureable Resin used to fabricate the structure of FMAV was evaluated and confirmed through tensile test. Secondly, a numerical computation model describing the mechanical behavior of FMAV transmission structure was established and verified by experiments. Then topology optimization modeling method considering non-linear factors were presented, and optimization results were verified by dynamic simulation and experiments. Finally, detail discussions of different load status and constraints were carried out to explore the leading factors affecting the optimization results. The contributions drawn from this article helpful for guiding the lightweight design of FMAV are summarizing as follow; first, a dynamic simulation modeling method used to obtain the load status is presented. Second, verification method of optimized results considering non-linear factors is introduced. Third, based on or can achieve a better weight reduction effect and improve the computational efficiency rather than taking multi-states into account. Fourth, basing on makes for improving the ability to resist bending deformation. Fifth, constraint of displacement helps to improve the structural stiffness of optimized result. Results and engineering guidance in this paper may shed lights on the structural optimization and light-weight design for future advanced FMAV.

Keywords: flapping-wing micro aerial vehicle, 3d printing, topology optimization, finite element analysis, experiment

Procedia PDF Downloads 166

Authors: Emanuela Zilli, Suana Tikvina, Davide Bonaldo, Monica Varotto, Scilla Rizzardi, Barbara Ruzzante, Raffaele Napolitano, Stefano Bevilacqua, Antonella Ruffatto

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A healthy workplace increases productivity, creativity and decreases absenteeism and turnover. It also contributes to creating a more secure work environment with fewer risks of violence. In the past 3 years, the healthcare system has suffered the psychological, economic and social consequences of the COVID-19 pandemic. On the other hand, the healthcare staff reductions determine high levels of work-related stress that are often unsustainable. The Hospital of Cittadella (in the province of Padua) has 400 beds and serves a territory of 300,000 inhabitants. The hospital itself counts 1.250 healthcare employees (healthcare professionals). This year, the Medical Board of Directors has requested additional staff; however, the economic situation of Italy can not sustain additional hires. At the same time, we have initiated projects that aim to increase well-being, decrease stress and encourage activities that promote self-care. One of the projects that the hospital has organized is the psychomotor practice. It is held by therapists and trainers who operate according to the traditional method. According to the literature, the psychomotor practice is specifically intended for the staff operating in the Intensive Care Unit, Emergency Department and Pneumology Ward. The project consisted of one session of 45 minutes a week for 3 months. This method brings focus to controlled breathing, posture, muscle work and movement that help manage stress and fatigue, creating a more mindful and sustainable lifestyle. In addition, a Qigong course was held every two weeks for 5 months. It is an ancient Chinese practice designed to optimize the energy within the body, reducing stress levels and increasing general well-being. Finally, Tibetan singing crystal bowls sessions, held by a music therapist, consisted of monthly guided meditation sessions using the sounds of the crystal bowls. Sound therapy uses the vibrations created from the crystal bowls to balance the vibrations within the body to promote relaxation. In conclusion, well-being and organizational performance are closely related to each other. It is crucial for any organization to encourage and maintain better physical and mental health of the healthcare staff as it directly affects productivity and, consequently, user satisfaction of the services provided.

Keywords: health promotion, healthcare workers management, Weel being and organizational performance, Psychomotor practice

Procedia PDF Downloads 59

Authors: Hamed Khosravi, Reza Eslami-Farsani

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Increased interest in lightweight and efficient structural components has created the need for selecting materials with improved mechanical properties. To do so, composite materials are being widely used in many applications, due to durability, high strength and modulus, and low weight. Among the various composite structures, grid-stiffened structures are extensively considered in various aerospace and aircraft applications, because of higher specific strength and stiffness, higher impact resistance, superior load-bearing capacity, easy to repair, and excellent energy absorption capability. Although there are a good number of publications on the design aspects and fabrication of grid structures, little systematic work has been reported on their material modification to improve their properties, to our knowledge. Therefore, the aim of this research is to study the reinforcing effect of silica nanoparticles on the flexural properties of epoxy/E-glass isogrid panels under three-point bending test. Samples containing 0, 1, 3, and 5 wt.% of the silica nanoparticles, with 44 and 48 vol.% of the glass fibers in the ribs and skin components respectively, were fabricated by using a manual filament winding method. Ultrasonic and mechanical routes were employed to disperse the nanoparticles within the epoxy resin. To fabricate the ribs, the unidirectional fiber rovings were impregnated with the matrix mixture (epoxy + nanoparticles) and then laid up into the grooves of a silicone mold layer-by-layer. At once, four plies of woven fabrics, after impregnating into the same matrix mixture, were layered on the top of the ribs to produce the skin part. In order to conduct the ultimate curing and to achieve the maximum strength, the samples were tested after 7 days of holding at room temperature. According to load-displacement graphs, the bellow trend was observed for all of the samples when loaded from the skin side; following an initial linear region and reaching a load peak, the curve was abruptly dropped and then showed a typical absorbed energy region. It would be worth mentioning that in these structures, a considerable energy absorption was observed after the primary failure related to the load peak. The results showed that the flexural properties of the nanocomposite samples were always higher than those of the nanoparticle-free sample. The maximum enhancement in flexural maximum load and energy absorption was found to be for the incorporation of 3 wt.% of the nanoparticles. Furthermore, the flexural stiffness was continually increased by increasing the silica loading. In conclusion, this study suggested that the addition of nanoparticles is a promising method to improve the flexural properties of grid-stiffened fibrous composite structures.

Keywords: grid-stiffened composite structures, nanocomposite, three point flexural test , energy absorption

Procedia PDF Downloads 334

Authors: A. L. Verret, N. Prince, Y. Jerome, A. Bras

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The effects of housing design on the health and well-being of populations are quite intangible. In fact, healthy housing parameters are generally difficult to establish scientifically. It is often unclear the direction of a cause-and-effect relationship between health variables and housing. However, the lack of clear and definite measurements does not entail the absence of relationship between housing, health, and well-being. Research has thus been conducted. It has mostly aimed the physical rather than the psychological or social well-being of a population, given the difficulties to establish cause-effect relationships because of the subjectivity of the psychological symptoms and of the challenge in determining the influence of other factors. That said, a strong relationship has been exposed between light and physiology. Both the nervous and endocrine systems, amongst others, are affected by different wavelengths of natural light within a building. Daylight in the workplace is indeed associated to decreased absenteeism, errors and product defects, fatigue, eyestrain, increased productivity and positive attitude. Similar associations can also be made to residential housing. Lower levels of sunlight within the home have been proven to result in impaired cognition in depressed participants of a cross-sectional case study. Moreover, minimum space (area and volume) has been linked to healthy housing and quality of life, resulting in norms and regulations for such parameters for home constructions. As a matter of fact, it is estimated that people spend the two-thirds of their lives within the home and its immediate environment. Therefore, it is possible to deduct that the health and well-being of the occupants are potentially at risk in an unhealthy housing situation. While the impact of architecture on health and well-being is acknowledged and considered somewhat crucial in various countries of the north and the south, this issue is barely raised in Haiti. In fact, little importance is given to architecture for many reasons (lack of information, lack of means, societal reflex, poverty…). However, the middle-class is known for its residential strategies and trajectories in search of better-quality homes and environments. For this reason, it would be pertinent to use this group and its strategies and trajectories to isolate the impact of housing design on the overall health and well-being. This research aims to analyze the impact of housing architecture on the health and well-being of middle-class families in the metropolitan region of Port-au-Prince. It is a case study which uses semi-structured interviews and observations as research methods. Although at an early stage, this research anticipates that homes affect their occupants both psychologically and physiologically, and consequently, public policies and the population should take into account the architectural design in the planning and construction of housing and, furthermore, cities.

Keywords: architectural design, health and well-being, middle-class housing, Port-au-Prince, Haiti

Procedia PDF Downloads 133

Authors: Keda Li, Hong Hu

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Auxetic materials, as an emerging artificial designed metamaterial has attracted growing attention due to their promising negative Poisson’s ratio behaviors and tunable properties. The conventional auxetic lattice structures for which the deformation process is governed by a bending-dominated mechanism have faced the limitation of poor mechanical performance for many potential engineering applications. Recently, both load-bearing and energy absorption capabilities have become a crucial consideration in auxetic structure design. This study reports the finite element analysis of a class of hexagonal double-arrowhead auxetic structures with enhanced stiffness and energy absorption performance. The structure design was developed by extending the traditional double-arrowhead honeycomb to a hexagon frame, the stretching-dominated deformation mechanism was determined according to Maxwell’s stability criterion. The finite element (FE) models of 2D lattice structures established with stainless steel material were analyzed in ABAQUS/Standard for predicting in-plane structural deformation mechanism, failure process, and compressive elastic properties. Based on the computational simulation, the parametric analysis was studied to investigate the effect of the structural parameters on Poisson’s ratio and mechanical properties. The geometrical optimization was then implemented to achieve the optimal Poisson’s ratio for the maximum specific energy absorption. In addition, the optimized 2D lattice structure was correspondingly converted into a 3D geometry configuration by using the orthogonally splicing method. The numerical results of 2D and 3D structures under compressive quasi-static loading conditions were compared separately with the traditional double-arrowhead re-entrant honeycomb in terms of specific Young's moduli, Poisson's ratios, and specified energy absorption. As a result, the energy absorption capability and stiffness are significantly reinforced with a wide range of Poisson’s ratio compared to traditional double-arrowhead re-entrant honeycomb. The auxetic behaviors, energy absorption capability, and yield strength of the proposed structure are adjustable with different combinations of joint angle, struts thickness, and the length-width ratio of the representative unit cell. The numerical prediction in this study suggests the proposed concept of hexagonal double-arrowhead structure could be a suitable candidate for the energy absorption applications with a constant request of load-bearing capacity. For future research, experimental analysis is required for the validation of the numerical simulation.

Keywords: auxetic, energy absorption capacity, finite element analysis, negative Poisson's ratio, re-entrant hexagonal honeycomb

Procedia PDF Downloads 83

Authors: Richard J. Hanowski, Rebecca L. Hammond

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Very few studies have been conducted to investigate safety issues associated with motorcoach/bus operations. The current study investigates the impact that roadway infrastructure, including locality, roadway grade, traffic flow and traffic density, have on bus safety. A naturalistic driving study was conducted in the U.S.A that involved 43 motorcoaches. Two fleets participated in the study and over 600,000 miles of naturalistic driving data were collected. Sixty-five bus drivers participated in this study; 48 male and 17 female. The average age of the drivers was 49 years. A sophisticated data acquisition system (DAS) was installed on each of the 43 motorcoaches and a variety of kinematic and video data were continuously recorded. The data were analyzed by identifying safety critical events (SCEs), which included crashes, near-crashes, crash-relevant conflicts, and unintentional lane deviations. Additionally, baseline (normative driving) segments were also identified and analyzed for comparison to the SCEs. This presentation highlights the need for bus safety research and the methods used in this data collection effort. With respect to elements of roadway infrastructure, this study highlights the methods used to assess locality, roadway grade, traffic flow, and traffic density. Locality was determined by manual review of the recorded video for each event and baseline and was characterized in terms of open country, residential, business/industrial, church, playground, school, urban, airport, interstate, and other. Roadway grade was similarly determined through video review and characterized in terms of level, grade up, grade down, hillcrest, and dip. The video was also used to make a determination of the traffic flow and traffic density at the time of the event or baseline segment. For traffic flow, video was used to assess which of the following best characterized the event or baseline: not divided (2-way traffic), not divided (center 2-way left turn lane), divided (median or barrier), one-way traffic, or no lanes. In terms of traffic density, level-of-service categories were used: A1, A2, B, C, D, E, and F. Highlighted in this abstract are only a few of the many roadway elements that were coded in this study. Other elements included lighting levels, weather conditions, roadway surface conditions, relation to junction, and roadway alignment. Note that a key component of this study was to assess the impact that driver distraction and fatigue have on bus operations. In this regard, once the roadway elements had been coded, the primary research questions that were addressed were (i) “What environmental condition are associated with driver choice of engagement in tasks?”, and (ii) “what are the odds of being in a SCE while engaging in tasks while encountering these conditions?”. The study may be of interest to researchers and traffic engineers that are interested in the relationship between roadway infrastructure elements and safety events in motorcoach bus operations.

Keywords: bus safety, motorcoach, naturalistic driving, roadway infrastructure

Procedia PDF Downloads 177

Authors: Takaaki Nemoto

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Case presentation: A 69-year-old Japanese man presented with a low-grade fever and fatigue that had persisted for one month. The patient had an aortic dissection on the aortic arch 13 years prior, an abdominal aortic aneurysm seven years prior, and an aortic dissection on the distal aortic arch one year prior, which were all treated with artificial blood-vessel replacement surgery. Laboratory tests revealed an inflammatory response (CRP 7.61 mg/dl), high serum creatinine (Cr 1.4 mg/dL), and elevated transaminase (AST 47 IU/L, ALT 45 IU/L). The patient was admitted to our hospital on suspicion of prosthetic vascular graft infection. Following further workups on the inflammatory response, an enhanced chest computed tomography (CT) and a non-enhanced chest DWI (MRI) were performed. The patient was diagnosed with a pulmonary fistula and a prosthetic vascular graft infection on the distal aortic arch. After admission, the patient was administered Ceftriaxion and Vancomycine for 10 days, but his fever and inflammatory response did not improve. On day 13 of hospitalization, a lung fistula repair surgery and an omental filling operation were performed, and Meropenem and Vancomycine were administered. The fever and inflammatory response continued, and therefore we took repeated blood cultures. M. fortuitum was detected in a blood culture on day 16 of hospitalization. As a result, we changed the treatment regimen to Amikacin (400 mg/day), Meropenem (2 g/day), and Cefmetazole (4 g/day), and the fever and inflammatory response began to decrease gradually. We performed a test of sensitivity for Mycobacterium fortuitum, and found that the MIC was low for fluoroquinolone antibacterial agent. The clinical course was good, and the patient was discharged after a total of 8 weeks of intravenous drug administration. At discharge, we changed the treatment regimen to Levofloxacin (500 mg/day) and Clarithromycin (800 mg/day), and prescribed these two drugs as a long life suppressive therapy. Discussion: There are few cases of prosthetic vascular graft infection caused by mycobacteria, and a standard therapy remains to be established. For prosthetic vascular graft infections, it is ideal to provide surgical and medical treatment in parallel, but in this case, surgical treatment was difficult and, therefore, a conservative treatment was chosen. We attempted to increase the treatment success rate of this refractory disease by conducting a susceptibility test for mycobacteria and treating with different combinations of antimicrobial agents, which was ultimately effective. With our treatment approach, a good clinical course was obtained and continues at the present stage. Conclusion: Although prosthetic vascular graft infection resulting from mycobacteria is a refractory infectious disease, it may be curative to administer appropriate antibiotics based on the susceptibility test in addition to surgical treatment.

Keywords: prosthetic vascular graft infection, lung fistula, Mycobacterium fortuitum, conservative treatment

Procedia PDF Downloads 149

Authors: C. Amer, M. Sahin

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The design of an optimised horizontal axis 5-meter-long wind turbine rotor blade in according with IEC 61400-2 standard is a research and development project in order to fulfil the requirements of high efficiency of torque from wind production and to optimise the structural components to the lightest and strongest way possible. For this purpose, a research study is presented here by focusing on the structural characteristics of a composite wind turbine blade via finite element modelling and analysis tools. In this work, first, the required data regarding the general geometrical parts are gathered. Then, the airfoil geometries are created at various sections along the span of the blade by using CATIA software to obtain the two surfaces, namely; the suction and the pressure side of the blade in which there is a hat shaped fibre reinforced plastic spar beam, so-called chassis starting at 0.5m from the root of the blade and extends up to 4 m and filled with a foam core. The root part connecting the blade to the main rotor differential metallic hub having twelve hollow threaded studs is then modelled. The materials are assigned as two different types of glass fabrics, polymeric foam core material and the steel-balsa wood combination for the root connection parts. The glass fabrics are applied using hand wet lay-up lamination with epoxy resin as METYX L600E10C-0, is the unidirectional continuous fibres and METYX XL800E10F having a tri-axial architecture with fibres in the 0,+45,-45 degree orientations in a ratio of 2:1:1. Divinycell H45 is used as the polymeric foam. The finite element modelling of the blade is performed via MSC PATRAN software with various meshes created on each structural part considering shell type for all surface geometries, and lumped mass were added to simulate extra adhesive locations. For the static analysis, the boundary conditions are assigned as fixed at the root through aforementioned bolts, where for dynamic analysis both fixed-free and free-free boundary conditions are made. By also taking the mesh independency into account, MSC NASTRAN is used as a solver for both analyses. The static analysis aims the tip deflection of the blade under its own weight and the dynamic analysis comprises normal mode dynamic analysis performed in order to obtain the natural frequencies and corresponding mode shapes focusing the first five in and out-of-plane bending and the torsional modes of the blade. The analyses results of this study are then used as a benchmark prior to modal testing, where the experiments over the produced wind turbine rotor blade has approved the analytical calculations.

Keywords: dynamic analysis, fiber reinforced composites, horizontal axis wind turbine blade, hand-wet layup, modal testing

Procedia PDF Downloads 419

Authors: Ali A Alshraifeen, Josie Evans, Kathleen Stoddart

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End-stage renal disease (ESRD) introduces physical, psychological, social, emotional and spiritual challenges into patients’ lives. Spirituality has been found to contribute to improved health outcomes, mainly in the areas of quality of life (QOL) and well-being. No studies exist to explore the influence of spirituality on the health outcomes and general well-being in patients with end-stage renal disease receiving hemodialysis (HD) treatment in Scotland. This study was conducted to explore spirituality in the daily lives of among these patients and how it may influence their QOL and general well-being. The study employed a qualitative method. Data were collected using semi-structured interviews with a sample of 21 patients. A thematic approach using Framework Analysis informed the qualitative data analysis. Participants were recruited from 11 dialysis units across four Health Boards in Scotland. The participants were regular patients attending the dialysis units three times per week. Four main themes emerged from the qualitative interviews: ‘Emotional and Psychological Turmoil’, ‘Life is Restricted’, ‘Spirituality’ and ‘Other Coping Strategies’. The findings suggest that patients’ QOL might be affected because of the physical challenges such as unremitting fatigue, disease unpredictability and being tied down to a dialysis machine, or the emotional and psychological challenges imposed by the disease into their lives such as wholesale changes, dialysis as a forced choice and having a sense of indebtedness. The findings also revealed that spirituality was an important coping strategy for the majority of participants who took part in the qualitative component (n=16). Different meanings of spirituality were identified including connection with God or Supernatural Being, connection with the self, others and nature/environment. Spirituality encouraged participants to accept their disease and offered them a sense of protection, instilled hope in them and helped them to maintain a positive attitude to carry on with their daily lives, which may have had a positive influence on their health outcomes and general well-being. The findings also revealed that humor was another coping strategy that helped to diffuse stress and anxiety for some participants and encouraged them to carry on with their lives. The findings from this study provide a significant contribution to a very limited body of work. The study contributes to our understanding of spirituality and how people receiving dialysis treatment use it to manage their daily lives. Spirituality is of particular interest due to its connection with health outcomes in patients with chronic illnesses. The link between spirituality and many chronic illnesses has gained some recognition, yet the identification of its influence on the health outcomes and well-being in patients with ESRD is still evolving. There is a need to understand patients’ experiences and examine the factors that influence their QOL and well-being to ensure that the services available are adequately tailored to them. Hence, further research is required to obtain a better understanding of the influence of spirituality on the health outcomes and general well-being of patients with ESRD.

Keywords: end-stage renal disease, general well-being, quality of life, spirituality

Procedia PDF Downloads 224

Authors: Yasmeen Jamal Alabdallat, Almutazballlah Bassam Qablan, Hamza Al-Salhi, Salameh Alarood, Ibraheem Alkhawaldeh, Obada Abunar, Adam Abdallah

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Obstructive sleep apnea (OSA) is a disorder caused by the repeated collapse of the upper airway during sleep. It is the most common cause of sleep-related breathing disorder, as OSA can cause loud snoring, daytime fatigue, or more severe problems such as high blood pressure, cardiovascular disease, coronary artery disease, insulin-resistant diabetes, and depression. The hypoglossal nerve stimulator (HNS) is an implantable medical device that reduces the occurrence of obstructive sleep apnea by electrically stimulating the hypoglossal nerve in rhythm with the patient's breathing, causing the tongue to move. This stimulation helps keep the patient's airways clear while they sleep. This systematic review and meta-analysis aimed to assess the clinical outcome of hypoglossal nerve stimulation as a treatment of obstructive sleep apnea. A computer literature search of PubMed, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials was conducted from inception until August 2022. Studies assessing the following clinical outcomes (Apnea-Hypopnea Index (AHI), Epworth Sleepiness Scale (ESS), Functional Outcomes of Sleep Questionnaire (FOSQ), Oxygen Desaturation Indices (ODI), (Oxygen Saturation (SaO2)) were pooled in the meta-analysis using Review Manager Software. We assessed the quality of studies according to the Cochrane risk-of-bias tool for randomized trials (RoB2), Risk of Bias In Non-randomized Studies - of Interventions (ROBINS-I), and a modified version of NOS for the non-comparative cohort studies.13 Studies (Six Clinical Trials and Seven prospective cohort studies) with a total of 817 patients were included in the meta-analysis. The results of AHI were reported in 11 studies examining OSA 696 patients. We found that there was a significant improvement in the AHI after 12 months of HNS (MD = 18.2 with 95% CI, (16.7 to 19.7; I2 = 0%); P < 0.00001). Further, 12 studies reported the results of ESS after 12 months of intervention with a significant improvement in the range of sleepiness among the examined 757 OSA patients (MD = 5.3 with 95% CI, (4.75 to 5.86; I2 = 65%); P < 0.0001). Moreover, nine studies involving 699 participants reported the results of FOSQ after 12 months of HNS with a significant reported improvement (MD = -3.09 with 95% CI, (-3.41 to 2.77; I2 = 0%); P < 0.00001). In addition, ten studies reported the results of ODI with a significant improvement after 12 months of HNS among the 817 examined patients (MD = 14.8 with 95% CI, (13.25 to 16.32; I2 = 0%); P < 000001). The Hypoglossal Nerve Stimulation showed a significant positive impact on obstructive sleep apnea patients after 12 months of therapy in terms of apnea-hypopnea index, oxygen desaturation indices, manifestations of the behavioral morbidity associated with obstructive sleep apnea, and functional status resulting from sleepiness.

Keywords: apnea, meta-analysis, hypoglossal, stimulation

Procedia PDF Downloads 107

Authors: Cemil Atakara, Hüseyin Eryaman

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The use of glass as an envelope of a building has been increasing in the twentieth century. For more transparency and dematerialization new glass facade types have emerged in the past two decades which depends on point fixed glazing system (PFGS). The aim of this study is to analyze of the PFGS systems which are used on the glass curtain wall according to their types, degree, architectural and structural effects. This new system is desired because it enhances the transparency of the façade and it minimizes the component of the frames or of the profiles. This PFGS led to new structural elements which use cables, rods, trusses when designing a glass building facades, this structural element called the suspended glass system with pre-stressed cable truss (SGSPCT) which has been used for the first time in 1980 in Serres building. The twenty glass buildings which are designed in different systems have been analyzed during this study. After these analyses five selected SGSPCT building analyzed deeply and one skeletal frame building selected from Lefkosa redesigned according to the analysis results. These selected buildings have been included of various cable-truss system typologies and degree. The methodology of this study is building analysis method and literature survey with the help of books, articles, magazines, drawings, internet sources and applied connection details of the glass buildings. The selected five glass buildings and case building have been detailed analyzed with their architectural drawings, photographs and details. A gridshell structure can be compared with a shell structure; it consists of discrete members connecting nodal points. As these nodal points lie on the surface of an imaginary shell, their shapes function almost identically. Difference between shell and gridshell structures can be found in the fact that, due to their free-form and thus, due to the presence of bending forces, gridshells are required to resist loading through their cross-section. This research is divided into parts. A general study about the glass building and cable-glass and grid shell system will be done in the first chapters. Structural analyses and detailed analyses with schematic drawings with the plans, sections of the selected buildings will be explained in the second part. The third part it consists of the advantages and disadvantages of the use of the SGSPCT and Grid Shell in architecture. The study consists of four chapters including the introduction chapter. The general information of the SGSPCT and glazing system has been mentioned in the first chapter. Structural features, typologies, transparency principle and analytical information on systems have been explained of the selected buildings in the second chapter. The detailed analyses of case building have been done according to their schematic drawings with the plans, sections in the third chapter. After third chapter SGSPCT discussed on to the case building and selected buildings. SGSPCT systems have been compared with their advantages and disadvantages to the other systems. Advantages of cable-truss systems and SGSPCT have been concluded that the use of glass substrates in the last chapter.

Keywords: cable truss, glass, grid shell, transparency

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Authors: M. N. Baig, F. N. Khan, M. Junaid

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Titanium alloys are widely employed in aerospace, medical, chemical, and marine applications. These alloys offer many advantages such as low specific weight, high strength to weight ratio, excellent corrosion resistance, high melting point and good fatigue behavior. These attractive properties make titanium alloys very unique and therefore they require special attention in all areas of processing, especially welding. In this work, 1.6 mm thick sheets of Ti-5Al-2,5Sn, an alpha titanium (α-Ti) alloy, were welded using electron beam (EBW) and laser beam (LBW) welding processes to achieve a full penetration Bead-on Plate (BoP) configuration. The weldments were studied using polarized optical microscope, SEM, EDS and XRD. Microhardness distribution across the weld zone and smooth and notch tensile strengths of the weldments were also recorded. Residual stresses using Hole-drill Strain Measurement (HDSM) method and deformation patterns of the weldments were measured for the purpose of comparison of the two welding processes. Fusion zone widths of both EBW and LBW weldments were found to be approximately equivalent owing to fairly similar high power densities of both the processes. Relatively less oxide content and consequently high joint quality were achieved in EBW weldment as compared to LBW due to vacuum environment and absence of any shielding gas. However, an increase in heat-affected zone width and partial ά-martensitic transformation infusion zone of EBW weldment were observed because of lesser cooling rates associated with EBW as compared with LBW. The microstructure infusion zone of EBW weldment comprised both acicular α and ά martensite within the prior β grains whereas complete ά martensitic transformation was observed within the fusion zone of LBW weldment. Hardness of the fusion zone in EBW weldment was found to be lower than the fusion zone of LBW weldment due to the observed microstructural differences. Notch tensile specimen of LBW exhibited higher load capacity, ductility, and absorbed energy as compared with EBW specimen due to the presence of high strength ά martensitic phase. It was observed that the sheet deformation and deformation angle in EBW weldment were more than LBW weldment due to relatively more heat retention in EBW which led to more thermal strains and hence higher deformations and deformation angle. The lowest residual stresses were found in LBW weldments which were tensile in nature. This was owing to high power density and higher cooling rates associated with LBW process. EBW weldment exhibited highest compressive residual stresses due to which the service life of EBW weldment is expected to improve.

Keywords: Laser and electron beam welding, Microstructure and mechanical properties, Residual stress and distortions, Titanium alloys

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Authors: Abid Hussain, Binay Kumar

Abstract:

Environment-friendly lead-free Na₀.₅₂K₀.₄₄Li₀.₀₄Nb₀.₈₄Ta₀.₁₀Sb₀.₀₆O₃ (NKLNTS) ceramic was synthesized by solid-state reaction method in search of a potential candidate to replace lead-based ceramics such as PbZrO₃-PbTiO₃ (PZT), Pb(Mg₁/₃Nb₂/₃)O₃-PbTiO₃ (PMN-PT) etc., for various applications. The ceramic was calcined at temperature 850 ᵒC and sintered at 1090 ᵒC. The powder X-Ray Diffraction (XRD) pattern revealed the formation of pure perovskite phase having tetragonal symmetry with space group P4mm of the synthesized ceramic. The surface morphology of the ceramic was studied using Field Emission Scanning Electron Microscopy (FESEM) technique. The well-defined grains with homogeneous microstructure were observed. The average grain size was found to be ~ 0.6 µm. A very large value of piezoelectric charge coefficient (d₃₃ ~ 754 pm/V) was obtained for the synthesized ceramic which indicated its potential for use in transducers and actuators. In dielectric measurements, a high value of ferroelectric to paraelectric phase transition temperature (Tm~305 ᵒC), a high value of maximum dielectric permittivity ~ 2110 (at 1 kHz) and a very small value of dielectric loss ( < 0.6) were obtained which suggested the utility of NKLNTS ceramic in high-temperature ferroelectric devices. Also, the degree of diffuseness (γ) was found to be 1.61 which confirmed a relaxor ferroelectric behavior in NKLNTS ceramic. P-E hysteresis loop was traced and the value of spontaneous polarization was found to be ~11μC/cm² at room temperature. The pyroelectric coefficient was obtained to be very high (p ∼ 1870 μCm⁻² ᵒC⁻¹) for the present case indicating its applicability in pyroelectric detector applications including fire and burglar alarms, infrared imaging, etc. NKLNTS ceramic showed fatigue free behavior over 107 switching cycles. Remanent hysteresis task was performed to determine the true-remanent (or intrinsic) polarization of NKLNTS ceramic by eliminating non-switchable components which showed that a major portion (83.10 %) of the remanent polarization (Pr) is switchable in the sample which makes NKLNTS ceramic a suitable material for memory switching devices applications. Time-Dependent Compensated (TDC) hysteresis task was carried out which revealed resistive leakage free nature of the ceramic. The performance of NKLNTS ceramic was found to be superior to many lead based piezoceramics and hence can effectively replace them for use in piezoelectric, pyroelectric and long duration ferroelectric applications.

Keywords: dielectric properties, ferroelectric properties , lead free ceramic, piezoelectric property, solid state reaction, true-remanent polarization

Procedia PDF Downloads 132

Authors: Sina Kazemi, Farshid Torabi, Todd Peterson

Abstract:

Drilling in shale formations is frequently time-consuming, challenging, and fraught with mechanical failures such as stuck pipes or hole packing off when the cutting removal rate is not sufficient to clean the bottom hole. Crossing the heavy oil shale and sand reservoirs with active shale and microfractures is generally associated with severe fluid losses causing a reduction in the rate of the cuttings removal. These circumstances compromise a well’s integrity and result in a lower rate of penetration (ROP). This study presents collective results of field studies and theoretical analysis conducted on data from South Pars and North Dome in an Iran-Qatar offshore field. Solutions to complications related to drilling in shale formations are proposed through systemically analyzing and applying modeling techniques to select field mud logging data. Field data measurements during actual drilling operations indicate that in a shale formation where the return flow of polymer mud was almost lost in the upper dolomite layer, the performance of hole cleaning and ROP progressively change when higher string rotations are initiated. Likewise, it was observed that this effect minimized the force of rotational torque and improved well integrity in the subsequent casing running. Given similar geologic conditions and drilling operations in reservoirs targeting shale as the producing zone like the Bakken formation within the Williston Basin and Lloydminster, Saskatchewan, a drill bench dynamic modeling simulation was used to simulate borehole cleaning efficiency and mud optimization. The results obtained by altering RPM (string revolution per minute) at the same pump rate and optimized mud properties exhibit a positive correlation with field measurements. The field investigation and developed model in this report show that increasing the speed of string revolution as far as geomechanics and drilling bit conditions permit can minimize the risk of mechanically stuck pipes while reaching a higher than expected ROP in shale formations. Data obtained from modeling and field data analysis, optimized drilling parameters, and hole cleaning procedures are suggested for minimizing the risk of a hole packing off and enhancing well integrity in shale reservoirs. Whereas optimization of ROP at a lower pump rate maintains the wellbore stability, it saves time for the operator while reducing carbon emissions and fatigue of mud motors and power supply engines.

Keywords: ROP, circulating density, drilling parameters, return flow, shale reservoir, well integrity

Procedia PDF Downloads 81

Authors: Natalie A. Sterk, Bernard van Vuuren, Petrie Marais, Bongani Mthombeni

Abstract:

Injuries to the internal structures of the thorax and abdomen remain a leading cause of death among soldiers. Body armour is a standard issue piece of military equipment designed to protect the vital organs against ballistic and stab threats. When configured for maximum protection, the excessive weight and size of the armour may limit soldier mobility and increase physical fatigue and discomfort. Providing soldiers with more armour than necessary may, therefore, hinder their ability to react rapidly in life-threatening situations. The capability to determine the optimal trade-off between the amount of essential anatomical coverage and hindrance on soldier performance may significantly enhance the design of armour systems. The current study aimed to develop and pilot a methodology for relating internal anatomical structures with actual armour plate coverage in real-time using low-dose diagnostic X-ray scanning. Several pilot scanning sessions were held at Lodox Systems (Pty) Ltd head-office in South Africa. Testing involved using the Lodox eXero-dr to scan dummy trunk rigs at various degrees and heights of measurement; as well as human participants, wearing correctly fitted body armour while positioned in supine, prone shooting, seated and kneeling shooting postures. The verification of sizing and metrics obtained from the Lodox eXero-dr were then confirmed through a verification board with known dimensions. Results indicated that the low-dose diagnostic X-ray has the capability to clearly identify the vital internal structures of the aortic arch, heart, and lungs in relation to the position of the external armour plates. Further testing is still required in order to fully and accurately identify the inferior liver boundary, inferior vena cava, and spleen. The scans produced in the supine, prone, and seated postures provided superior image quality over the kneeling posture. The X-ray-source and-detector distance from the object must be standardised to control for possible magnification changes and for comparison purposes. To account for this, specific scanning heights and angles were identified to allow for parallel scanning of relevant areas. The low-dose diagnostic X-ray provides a non-invasive, safe, and rapid technique for relating vital internal structures with external structures. This capability can be used for the re-evaluation of anatomical coverage required for essential protection while optimising armour design and fit for soldier performance.

Keywords: body armour, low-dose diagnostic X-ray, scanning, vital organ coverage

Procedia PDF Downloads 119

Authors: Nabil Omar, Farah Jibril, Oraib Amjad

Abstract:

Purpose: Trabecatine is a is a potent marine-derived antineoplastic drug which binds to the minor groove of the DNA, bending DNA towards the major groove resulting in a changed conformation that interferes with several DNA transcription factors, repair pathways and cell proliferation. Trabectedin was approved by the European Medicines Agency (EMA; London, UK) for the treatment of adult patients with advanced stage soft tissue sarcomas in whom treatment with anthracyclines and ifosfamide has failed, or for those who are not candidates for these therapies. The recommended dosing regimen is 1.5 mg/m2 IV over 24 hours every 3 weeks. The purpose of this study was to comprehensively review available data on the safety and efficacy of trabectedin used as indicated for patients at a Tertiary Cancer Center at Qatar. Methods: A medication administration report generated in the electronic health record identified all patients who received trabectedin between November 1, 2015 and November 1, 2017. This retrospective chart review evaluated the indication of trabectedin use, compliance to administration protocol and the recommended monitoring parameters, number of patients improved on the drug and continued treatment, number of patients discontinued treatment due to side-effects and the reported side effects. Progress and discharged notes were utilized to report experienced side effects during trabectedin therapy. A total of 3 patients were reviewed. Results: Total of 2 out of 3 patients who received trabectedin were receiving it for non-FDA and non-EMA, approved indications; metastatic rhabdomyosarcoma and ovarian cancer stage IV with poor prognosis. And only one patient received it as indicated for leiomyosarcoma of left ureter with metastases to liver, lungs and bone. None of the patients has continued the therapy due to development of serious side effects. One patient had stopped the medication after one cycle due to disease progression and transient hepatic toxicity, the other one had disease progression and developed 12 % reduction in LVEF after 12 cycles of trabectedin, and the third patient deceased, had disease progression on trabectedin after the 10th cycle that was received through peripheral line which resulted in developing extravasation and left arm cellulitis requiring debridement. Regarding monitoring parameters, at baseline the three patients had ECHO, and Creatine Phosphokinase (CPK) but it was not monitored during treatment as recommended. Conclusion: Utilizing this medication as indicated with performing the appropriate monitoring parameters as recommended can benefit patients who are receiving it. It is important to reinforce the intravenous administration via central intravenous line, the re-assessment of left ventricular ejection fraction (LVEF) by echocardiogram or multigated acquisition (MUGA) scan at 2- to 3-month intervals thereafter until therapy is discontinued, and CPK and LFTs levels prior to each administration of trabectedin.

Keywords: trabectedin, drug-use evaluation, safety, effectiveness, adverse drug reaction, monitoring

Procedia PDF Downloads 129