Search results for: lower extremity exoskeleton

Authors: Zachary N. Wing

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Compared to autoclave based processes, Resin Transfer Molding (RTM) offers several key advantages. This includes high internal and external complexity, less waste, lower volatile emissions, higher production rates, and excellent surface finish. However, the injection of high pressure-high temperature resin presents a tooling challenge in cases where trapped geometries exist. Tooling materials that can sustain these conditions and be easily removed would expand the use of RTM. We have performed research on developing an RTM suitable tooling material called 'RTMCore' for use in forming trapped geometries. RTMCore tooling materials can withstand the injection of high temperature-high pressure resin but be easily removed with tap water. RTM properties and performance capabilities are reviewed against other washout systems. Our research will cover the preliminary characterization of tooling system properties, mechanical behavior, and initial results from an RTM manufacturing trial. Preliminary results show the material can sustain pressures greater than 13 MPa and temperatures greater than 150°C.

Keywords: RTM, resin transfer molding, trapped geometries, washout tooling

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Authors: Karan Gupta

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The floods cause huge loos each year, and their impact gets manifold with the increase of total duration of flood as well as recession time. Moreover, floods have increased in recent years due to climate change in floodplains. In the context of global climate change, the agreement in Paris convention (2015) stated to keep the increase in global average temperature well below 2°C and keep it at the limit of 1.5°C. Thus, this study investigates the impact of increasing temperature on the stage, discharge as well as total flood duration and recession time in the Meghna River basin in Bangladesh. This study considers the 100-year return period flood flows in the Meghna river under the specific warming levels (SWLs) of 1.5°C, 2°C, and 4°C. The results showed that the rate of increase of duration of flood is nearly 50% lesser at ∆T = 1.5°C as compared to ∆T = 2°C, whereas the rate of increase of duration of recession is 75% lower at ∆T = 1.5°C as compared to ∆T = 2°C. Understanding the change of total duration of flood as well as recession time of the flood gives a better insight to effectively plan for flood mitigation measures.

Keywords: flood, climate change, Paris convention, Bangladesh, inundation duration, recession duration

Procedia PDF Downloads 142

Authors: Heeyoung Lee, Woosung Bin, Kangseog Seo, Hyojeong Yun, Zuog An

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Recently, a new continuous bridge system has been proposed to increase the space under the bridge and to improve aesthetic aspect of the urban area. The main feature of the proposed bridge is to connect steel I-girders and coping by means of prestressed high-strength steel bars and steel plate. The proposed bridge is able to lower the height of the bridge to ensure the workability and efficiency through a reduction of the cost of road construction. This study presents the experimental result of the full-scale connection between steel I-girders and coping under the negative bending moment. The composite behavior is thoroughly examined and discussed under the specific load levels such as service load, factored load and crack load. Structural response showed full composite action until the final load level because no relative displacement between coping and girder was observed. It was also found prestressing force into high-strength bars was able to control tensile stresses of deck slab. This indicated that cracks in deck slab can be controlled by above-mentioned prestressing force.

Keywords: coping, crack, integrated bridge, full-scale test

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Authors: Nisha Deopa, A. S. Rao

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Neodymium doped lithium lead alumino borate glasses were synthesized with the molar composition 10Li₂O – 10PbO – (10-x) Al₂O₃ – 70B₂O₃ – xNd₂O₃ (where, x = 0.1, 0.5, 1.0, 1.5, 2.0 and 2.5 mol %) via conventional melt quenching technique to understand their lasing potentiality. From the absorption spectra, Judd-Ofelt intensity parameters along with various spectroscopic parameters have been estimated. The emission spectra recorded for the as-prepared glasses under investigation exhibit two emission transitions, ⁴F₃/₂→⁴I₁₁/₂ (1063 nm) and ⁴F₃/₂→⁴I₉/₂ (1350 nm) for which radiative parameters have been evaluated. The emission intensity increases with increase in Nd³⁺ ion concentration up to 1 mol %, and beyond concentration quenching took place. The decay profile shows single exponential nature for lower Nd³⁺ ions concentration and non-exponential for higher concentration. To elucidate the nature of energy transfer process, non-exponential decay curves were well fitted to Inokuti-Hirayama model. The relatively high values of emission cross-section, branching ratio, lifetimes and quantum efficiency suggest that 1.0 mol% of Nd³⁺ in LiPbAlB glasses is aptly suitable to generate lasing action in NIR region at 1063 nm.

Keywords: energy transfer, glasses, J-O parameters, photoluminescence

Procedia PDF Downloads 189

Authors: Aferdita Dinaku, Jonida Canaj

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Aflatoxins are potentially toxic metabolites produced by certain kinds of fungi (molds) that are found naturally all over the world; they can contaminate food crops and pose a serious health threat to humans by mutagenic and carcinogenic effects. Several types of aflatoxin (14 or more) occur in nature. In Albanian nutrition, cereals (especially wheat and corn) are common ingredients in some traditional meals. This study aimed to investigate the presence of aflatoxins in the flour of wheat and maize that are consumed in Albania’s markets. The samples were collected randomly in different markets in Albania and detected by the ELISA method, measured in 450 nm. The concentration of total aflatoxins was analyzed by enzyme-linked immunosorbent assay (ELISA), and they were ranged between 0.05-1.09 ppb. However, the screened mycotoxin levels in the samples were lower than the maximum permissible limits of European Commission No 1881/2006 (4 μg/kg). The linearity of calibration curves was good for total aflatoxins (B1, B2, G1, G2, M1) (R²=0.99) in the concentration range 0.005-4.05 ppb. The samples were analyzed in two replicated measurements and for each sample, the standard deviation (statistical parameter) is calculated. The results showed that the flour samples are safe, but the necessity of performing such tests is necessary.

Keywords: aflatoxins, ELISA technique, food contamination, flour

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Authors: Hugo Daneluzzo, Christelle Rabbat, Alan Jean-Marie

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Water electrolysis is one of the most advanced technologies for producing hydrogen and can be easily combined with electricity from different sources. Under the influence of electric current, water molecules can be split into oxygen and hydrogen. The production of hydrogen by water electrolysis favors the integration of renewable energy sources into the energy mix by compensating for their intermittence through the storage of the energy produced when production exceeds demand and its release during off-peak production periods. Among the various electrolysis technologies, anion exchange membrane (AEM) electrolyser cells are emerging as a reliable technology for water electrolysis. Modeling and simulation are effective tools to save time, money, and effort during the optimization of operating conditions and the investigation of the design. The modeling and simulation become even more important when dealing with multiphysics dynamic systems. One of those systems is the AEM electrolysis cell involving complex physico-chemical reactions. Once developed, models may be utilized to comprehend the mechanisms to control and detect flaws in the systems. Several modeling methods have been initiated by scientists. These methods can be separated into two main approaches, namely equation-based modeling and graph-based modeling. The former approach is less user-friendly and difficult to update as it is based on ordinary or partial differential equations to represent the systems. However, the latter approach is more user-friendly and allows a clear representation of physical phenomena. In this case, the system is depicted by connecting subsystems, so-called blocks, through ports based on their physical interactions, hence being suitable for multiphysics systems. Among the graphical modelling methods, the bond graph is receiving increasing attention as being domain-independent and relying on the energy exchange between the components of the system. At present, few studies have investigated the modelling of AEM systems. A mathematical model and a bond graph model were used in previous studies to model the electrolysis cell performance. In this study, experimental data from literature were simulated using OpenModelica using bond graphs and mathematical approaches. The polarization curves at different operating conditions obtained by both approaches were compared with experimental ones. It was stated that both models predicted satisfactorily the polarization curves with error margins lower than 2% for equation-based models and lower than 5% for the bond graph model. The activation polarization of hydrogen evolution reactions (HER) and oxygen evolution reactions (OER) were behind the voltage loss in the AEM electrolyzer, whereas ion conduction through the membrane resulted in the ohmic loss. Therefore, highly active electro-catalysts are required for both HER and OER while high-conductivity AEMs are needed for effectively lowering the ohmic losses. The bond graph simulation of the polarisation curve for operating conditions at various temperatures has illustrated that voltage increases with temperature owing to the technology of the membrane. Simulation of the polarisation curve can be tested virtually, hence resulting in reduced cost and time involved due to experimental testing and improved design optimization. Further improvements can be made by implementing the bond graph model in a real power-to-gas-to-power scenario.

Keywords: hydrogen production, anion-exchange membrane, electrolyzer, mathematical modeling, multiphysics modeling

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Authors: Asma Ben Yaghlane, Mohamed Naceur Azaiez

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We consider the problem of attacks on networks. We define the concept of system survivability in networks in the presence of intelligent threats. Our setting of the problem assumes a flow to be sent from one source node to a destination node. The attacker attempts to disable the network by preventing the flow to reach its destination while the defender attempts to identify the best path-set to use to maximize the chance of arrival of the flow to the destination node. Our concept is shown to be different from the classical concept of network reliability. We distinguish two types of network survivability related to the defender and to the attacker of the network, respectively. We prove that the defender-based-network survivability plays the role of a lower bound while the attacker-based-network survivability plays the role of an upper bound of network reliability. We also prove that both concepts almost never agree nor coincide with network reliability. Moreover, we use the shortest-path problem to determine the defender-based-network survivability and the min-cut problem to determine the attacker-based-network survivability. We extend the problem to a variety of models including the minimum-spanning-tree problem and the multiple source-/destination-network problems.

Keywords: defense/attack strategies, information, networks, reliability, survivability

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Authors: Kawalpreet Kalra, Alpana Goel

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The behaviour of the rotational bands should be smooth but due to large amount of inertia and decreased pairing it is not so. Many experiments have been done in the last few decades, and a large amount of data is available for comprehensive study in this region. Peculiar features like signature dependence, signature inversion, and signature reversal are observed in many two quasiparticle rotational bands of doubly odd and doubly even nuclei. At high rotational frequencies, signature and parity are the only two good quantum numbers available to label a state. Signature quantum number is denoted by α. Even-angular momentum states of a rotational band have α =0, and the odd-angular momentum states have α =1. It has been observed that the odd-spin members lie lower in energy up to a certain spin Ic; the normal signature dependence is restored afterwards. This anomalous feature is termed as signature inversion. The systematic of signature inversion in high-j orbitals for doubly odd rare earth nuclei have been done. Many unusual features like signature dependence, signature inversion and signature reversal are observed in rotational bands of even-even/odd-odd nuclei. Attempts have been made to understand these phenomena using several models. These features have been analyzed within the framework of the Two Quasiparticle Plus Rotor Model (TQPRM).

Keywords: rotational bands, signature dependence, signature quantum number, two quasiparticle

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Authors: Sally Shepherd, Richard De Boer, Craig Murphy

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Background: Invasive lobular carcinoma (ILC) can metastasize to atypical sites within the peritoneal cavity, gastrointestinal, or genitourinary tract. Management varies depending on the symptom presentation, extent of disease burden, particularly if the primary disease is occult, and patient wishes. Case Series: 6 patients presented with general surgical presentations of ILC, including incomplete large bowel obstruction, cholecystitis, persistent lower abdominal pain, and faecal incontinence. 3 were diagnosed with their primary and metastatic disease in the same presentation, whilst 3 patients developed metastasis from 5 to 8 years post primary diagnosis of ILC. Management included resection of the metastasis (laparoscopic cholecystectomy), excision of the primary (mastectomy and axillary clearance), followed by a combination of aromatase inhibitors, biologic therapy, and chemotherapy. Survival post diagnosis of metastasis ranged from 3 weeks to 7 years. Conclusion: Metastatic ILC must be considered with any gastrointestinal or genitourinary symptoms in patients with a current or past history of ILC. Management may not be straightforward to chemotherapy if the acute pathology is resulting in a surgically resectable disease.

Keywords: breast cancer, gastrointestinal metastasis, invasive lobular carcinoma, metastasis

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Authors: N. O. Muniz, F. A. Vechietti, L. Treccani, K. Rezwan, Luis Alberto dos Santos

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Developing new technologies in the manufacture of biomaterials is a major challenge for researchers in the tissue engineering area. Many in vitro and in vivo studies have revealed the significance of the porous structure of the biomaterials on the promotion of bone ingrowth. The use of Rapid Prototyping in the manufacture of ceramics in the biomedical area has increased in recent years and few studies are conducted on obtaining alumina pieces. The aim of this work was the study of alumina pieces obtained by 3D printing and uniaxial dry pressing (DP) in order to evaluate porosity achieved by this two different techniques. Also, the influence of the powder drying process was determined. The row alumina powders were drying by freeze drying and oven. Apparent porosity, apparent density, retraction after thermal treatment were evaluated. The porosity values obtained by DP, regardless of method of drying powders, were much lower than those obtained by RP as expected. And for the prototyped samples, the method of powder drying significantly influenced porosities, reached 48% for drying oven versus 65% for freeze-drying. Therefore, the method of 3D printing, using different powder drying, allows a better control over the porosity.

Keywords: rapid prototyping, freeze-drying, porosity, alumina

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Authors: Bing-Wen Chen, Alvin W. Y. Su, Yu-Lin Wang

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Electromyography (EMG) is one of the important indicators during exercise, as it is closely related to the level of muscle activations. This work quantifies the muscle conditions of the lower limbs in a constant workload exercise. Surface EMG signals of the vastus laterals (VL), vastus medialis (VM), rectus femoris (RF), gastrocnemius medianus (GM), gastrocnemius lateral (GL) and Soleus (SOL) were recorded from fourteen healthy males. The EMG signals were segmented in two phases: activation segment (AS) and relaxation segment (RS). Period entropy (PE), peak count (PC), zero crossing (ZC), wave length (WL), mean power frequency (MPF), median frequency (MDF) and root mean square (RMS) are calculated to provide the quantitative information of the measured EMG segments. The outcomes reveal that the PE, PC, ZC and RMS have significantly changed (p<.001); WL presents moderately changed (p<.01); MPF and MDF show no changed (p>.05) during exercise. The results also suggest that the RS is also preferred for performance evaluation, while the results of the extracted features in AS are usually affected directly by the amplitudes. It is further found that the VL exhibits the most significant changes within six muscles during pedaling exercise. The proposed work could be applied to quantify the stamina analysis and to predict the instant muscle status in athletes.

Keywords: electromyographic feature extraction, muscle status, pedaling exercise, relaxation segment

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Authors: Mohammad R. Aghakashkooli, Milutin G. Jovanovic

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The brushless doubly-fed reluctance generator (BDFRG) is an emerging, medium-speed alternative to a conventional wound rotor slip-ring doubly-fed induction generator (DFIG) in wind energy conversion systems (WECS). It can provide competitive overall performance and similar low failure rates of a typically 30% rated back-to-back power electronics converter in 2:1 speed ranges but with the following important reliability and cost advantages over DFIG: the maintenance-free operation afforded by its brushless structure, 50% synchronous speed with the same number of rotor poles (allowing the use of a more compact, and more efficient two-stage gearbox instead of a vulnerable three-stage one), and superior grid integration properties including simpler protection for the low voltage ride through compliance of the fractional converter due to the comparatively higher leakage inductances and lower fault currents. Vector controlled pulse-width-modulated converters generally feature a much lower total harmonic distortion relative to hysteresis counterparts with variable switching rates and as such have been a predominant choice for BDFRG (and DFIG) wind turbines. Eliminating a shaft position sensor, which is often required for control implementation in this case, would be desirable to address the associated reliability issues. This fact has largely motivated the recent growing research of sensorless methods and developments of various rotor position and/or speed estimation techniques for this purpose. The main limitation of all the observer-based control approaches for grid-connected wind power applications of the BDFRG reported in the open literature is the requirement for pre-commissioning procedures and prior knowledge of the machine inductances, which are usually difficult to accurately identify by off-line testing. A model reference adaptive system (MRAS) based sensor-less vector control scheme to be presented will overcome this shortcoming. The true machine parameter independence of the proposed field-oriented algorithm, offering robust, inherently decoupled real and reactive power control of the grid-connected winding, is achieved by on-line estimation of the inductance ratio, the underlying rotor angular velocity and position MRAS observer being reliant upon. Such an observer configuration will be more practical to implement and clearly preferable to the existing machine parameter dependent solutions, and especially bearing in mind that with very little modifications it can be adapted for commercial DFIGs with immediately obvious further industrial benefits and prospects of this work. The excellent encoder-less controller performance with maximum power point tracking in the base speed region will be demonstrated by realistic simulation studies using large-scale BDFRG design data and verified by experimental results on a small laboratory prototype of the WECS emulation facility.

Keywords: brushless doubly fed reluctance generator, model reference adaptive system, sensorless vector control, wind energy conversion

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Authors: Emad Alenany, M. Adel El-Baz

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In this paper, the flow of different classes of patients into a hospital is modelled and analyzed by using the queueing network analyzer (QNA) algorithm and discrete event simulation. Input data for QNA are the rate and variability parameters of the arrival and service times in addition to the number of servers in each facility. Patient flows mostly match real flow for a hospital in Egypt. Based on the analysis of the waiting times, two approaches are suggested for improving performance: Separating patients into service groups, and adopting different service policies for sequencing patients through hospital units. The separation of a specific group of patients, with higher performance target, to be served separately from the rest of patients requiring lower performance target, requires the same capacity while improves performance for the selected group of patients with higher target. Besides, it is shown that adopting the shortest processing time and shortest remaining processing time service policies among other tested policies would results in, respectively, 11.47% and 13.75% reduction in average waiting time relative to first come first served policy.

Keywords: queueing network, discrete-event simulation, health applications, SPT

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Authors: Stephan P. Barkhuizen, Deon Greyling, Ryan J. Miller

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The accurate determination of the engineering parameters of soil is necessary for the design of geotechnical structures, such as Tailings Storage Facilities. The shear strength and saturated permeability of soil and tailings samples obtained from 14 sites located in the copper belt in the Democratic Republic of the Congo have been tested at six commercial soil laboratories in South Africa. This study compiles a database of the test results proved by the soil laboratories. The samples have been categorised into clay, silt, and sand, based on the Unified Soil Classification System, with tailings kept separate. The effective friction angle (Φ’) and cohesion (c’) were interpreted from the stress paths, in s’:t space, obtained from triaxial tests. The minimum, lower quartile, median, upper quartile, and maximum values for Φ’,c’, and saturated hydraulic conductivity (k) have been determined for the soil sample. The objective is to provide statistics of the measured values of the engineering properties for the TSF borrow material, foundation soils and tailings of this region.

Keywords: Democratic Republic of the Congo, laboratory test work, soil engineering parameter variation, tailings storage facilities

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Authors: Laila Mahtout, Kerami Ahmed, Rabhi Souhila

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The objective of this work is to reduce the impact on the environment of an acid dye (Black Eriochrome T) using catalytic photo-degradation in the presence of the semiconductor powder (TiO₂) previously characterized. A series of tests have been carried out in order to demonstrate the influence of certain parameters on the degree of dye degradation by titanium dioxide in the presence of UV rays, such as contact time, the powder mass and the pH of the solution. X-ray diffraction analysis of the powder showed that the anatase structure is predominant and the rutile phase is presented by peaks of low intensity. The various chemical groups which characterize the presence of the bands corresponding to the anatase and rutile form and other chemical functions have been detected by the Fourier Transform Infrared spectroscopy. The photo degradation of the NET by TiO₂ is very interesting because it gives encouraging results. The study of photo-degradation at different concentrations of the dye showed that the lower concentrations give better removal rates. The degree of degradation of the dye increases with increasing pH; it reaches the maximum value at pH = 9. The ideal mass of TiO₂ which gives the high removal rate is 1.2 g/l. Thermal treatment of TiO₂ with the addition of CuO with contents of 5%, 10%, and 15% respectively gives better results of degradation of the NET dye. The high percentage of elimination is observed at a CuO content of 15%.

Keywords: acid dye, ultraviolet rays, degradation, photocatalyse

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Authors: Harun Sepet, Necmettin Tarakcioglu

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The present study investigated the impact strength and fracture mechanism of nano-CaCO3 and nanoclay reinforced HDPE nanocomposites by using Charpy impact test. The nano-CaCO3 and nanoclay reinforced HDPE granules were prepared by the melt blending method using a compounder system, which consists of industrial banbury mixer, single screw extruder and granule cutting in industrial-scale. The nano-CaCO3 and nanoclay reinforced HDPE granules were molded using an injection-molding machine as plates, and then impact samples were cut by using punching die from the nanocomposite plates. As a result of impact experiments, nano-CaCO3 and nanoclay reinforced HDPE nanocomposites were determined to have lower impact energy level than neat HDPE. Also, the impact strength of HDPE further decreased by addition nanoclay compared to nano-CaCO3. The occurred fracture areas with the impact were detected by SEM examination. It is understood that fracture surface morphology changes when nano-CaCO3 and nanoclay ratio increases. The fracture surface changes were examined to determine the fracture mechanism of nano-CaCO3 and nanoclay reinforced HDPE nanocomposites.

Keywords: charpy, HDPE, industrial scale nano-CaCO3, nanoclay, nanocomposite

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Authors: Min Ye Koo, Gyo Woo Lee

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In this study, epoxy composite specimens reinforced with multi-walled carbon nanotube filler were fabricated using shear mixer and ultra-sonication processor. The mechanical and thermal properties of the fabricated specimens were measured and evaluated. From the electron microscope images and the results from the measurements of tensile strengths, the specimens having 0.6 wt% nanotube content show better dispersion and higher strength than those of the other specimens. The Young’s moduli of the specimens increased as the contents of the nanotube filler in the matrix were increased. The specimen having a 0.6 wt% nanotube filler content showed higher thermal conductivity than that of the other specimens. While, in the measurement of thermal expansion, specimens having 0.4 and 0.6 wt% filler contents showed a lower value of thermal expansion than that of the other specimens. On the basis of the measured and evaluated properties of the composites, we believe that the simple and time-saving fabrication process used in this study was sufficient to obtain improved properties of the specimens.

Keywords: carbon nanotube filler, epoxy composite, ultra-sonication, shear mixer, mechanical property, thermal property

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Authors: M. Amoura, M. Benmoussa, N. Zeraibi

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The flow and heat transfer is an important phenomenon in engineering systems due to its wide application in electronic cooling, heat exchangers, double pane windows etc.. The enhancement of heat transfer in these systems is an essential topic from an energy saving perspective. Lower heat transfer performance when conventional fluids, such as water, engine oil and ethylene glycol are used hinders improvements in performance and causes a consequent reduction in the size of such systems. The use of solid particles as an additive suspended into the base fluid is a technique for heat transfer enhancement. Therefore, the heat transfer enhancement in a horizontal circular tube that is maintained at a constant temperature under laminar regime has been investigated numerically. A computational code applied to the problem by use of the finite volume method was developed. Nanofluid was made by dispersion of Al2O3 nanoparticles in pure water and ethylene glycol. Results illustrate that the suspended nanoparticles increase the heat transfer with an increase in the nanoparticles volume fraction and for a considered range of Reynolds numbers. On the other hand, the heat transfer is very sensitive to the base fluid.

Keywords: Al2O3 nanoparticles, circular tube, heat transfert enhancement, numerical simulation

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Authors: Yakin Hajlaoui, Richard Labib, Jean-François Plante, Michel Gamache

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This study introduces the Multi-Layer Inverse Distance Weighting Model (ML-IDW), inspired by the mathematical formulation of both multi-layer neural networks (ML-NNs) and Inverse Distance Weighting model (IDW). ML-IDW leverages ML-NNs' processing capabilities, characterized by compositions of learnable non-linear functions applied to input features, and incorporates IDW's ability to learn anisotropic spatial dependencies, presenting a promising solution for nonlinear spatial interpolation and learning from complex spatial data. it employ gradient descent and backpropagation to train ML-IDW, comparing its performance against conventional spatial interpolation models such as Kriging and standard IDW on regression and classification tasks using simulated spatial datasets of varying complexity. the results highlight the efficacy of ML-IDW, particularly in handling complex spatial datasets, exhibiting lower mean square error in regression and higher F1 score in classification.

Keywords: deep learning, multi-layer neural networks, gradient descent, spatial interpolation, inverse distance weighting

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Authors: Meryem Abi-Ayad, Biagio Arcidiacono, Eusebio Chiefari, Daniela Foti, Mohamed Benyoucef, Antonio Brunetti

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Lipoprotein Lipase (LPL) is a key enzyme for lipid metabolism; its genetic polymorphism can be a candidate for modulating lipids parameters in metabolic syndrome. The objective of the present study was to determine whether lipoproteins lipase polymorphisMetS (LPL-HindIII) could be associated with moderate hypertriglyceridemia (secondary to metabolism syndrome). The polymorphism Hind III (rs320) was assessed by PCR-RFLP in 51 MetS patients and 17 healthy controls from the hospital in Tlemcen. The logistic regression analyses showed no significant association with Hind III genotype and hypertriglyceridemia (TG ≥ 1,5g/l or TG lower treatment) (P=0,455), metabolic syndrome (P=0,455), hypertension (P=0,802) and type 2 diabetes (P=0,144). In terms of plasma biomarkers, although not statistically significant, there was a difference in TG levels (P > 0,05), which was lowest among carriers of the homogenous mutant allele (H-). In this study, there was no association between the rare allele (H-) and disease protection, and between the frequent allele (H+) and disease prevalence (hypertriglyceridemia, metabolic syndrome, hypertension, type 2 diabetes).

Keywords: moderate secondary hypertriglyceridemia, metabolic syndrome, lipids, polymorphism lipoprotein lipase, HindIII(rs320)

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Authors: A. C. Galvis-Castro, R. D. Tovar, R. Salgado, M. Prezzi

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It is generally accepted that the shaft capacity of piles in the sand is lower for tensile loading that for compressive loading. So far, very little attention has been paid to the role of the influence of the installation method on the tensile to compressive shaft capacity ratio. The objective of this paper is to analyze the effect of installation method on the tensile to compressive shaft capacity of piles in dense sand as observed in tests on half-circular model pile tests in a half-circular calibration chamber with digital image correlation (DIC) capability. Model piles are either monotonically jacked, jacked with multiple strokes or pre-installed into the dense sand samples. Digital images of the model pile and sand are taken during both the installation and loading stages of each test and processed using the DIC technique to obtain the soil displacement and strain fields. The study provides key insights into the mobilization of shaft resistance in tensile and compressive loading for both displacement and non-displacement piles.

Keywords: digital image correlation, piles, sand, shaft resistance

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Authors: Shirin Aghanajafizadeh

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Nest site selection of Crested Lark was investigated in Boroyeh wildlife sanctuary of Harat during spring 2014. Habitat variables such as number of plant species, soil texture, distance to the nearest water resources, farms and roads were compared in the species presence plots with absence ones. Our analysis showed that the average number of Zygophyllum atriplicoidesand, Artemisia sieberi were higher while fine-textured soil percent cover (with very little and gravel) was lower in species presence plots than control plots. We resulted that the most affecting factor in the species nest site selection is the number of Z .atriplicoides and soil texture. Z. atriplicoides and A. sieberi can provide cover for nests and chickens against predators and environmental harsh events such as sunshine and wind. The stability of built nest forces the birds to select sites with not fine-textured soil. Some of the nests were detected in Alfalfa farms that can be related to its cover producing capability.

Keywords: habitat selection, Yazd Province, presence and absence plots, habitat variables

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Authors: Greg Zimmerman

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Background: Major depression is a common illness that affects millions of people globally. It is the leading cause of disability and is projected to become the number one cause of the global burden of disease by 2030. Many of those who suffer from depression also suffer from Irritable Bowel Syndrome (IBS). Acupuncture has been shown to help depression. The aim of this study was to investigate the effectiveness of acupuncture in reducing the risk of IBS in patients with depression. Methods: We enrolled patients diagnosed with depression through the Taiwanese National Health Insurance Research Database (NHIRD). Propensity score matching was used to match equal numbers (n=32971) of the acupuncture cohort and no-acupuncture cohort based on characteristics including sex, age, baseline comorbidity, and medication. The Cox regression model was used to compare the hazard ratios (HRs) of IBS in the two cohorts. Results: The basic characteristics of the two groups were similar. The cumulative incidence of IBS was significantly lower in the acupuncture cohort than in the no-acupuncture cohort (Log-rank test, p<0.001). Conclusion: The results provided real-world evidence that acupuncture may have a beneficial effect on IBS risk reduction in patients with depression.

Keywords: acupuncture, depression, irritable bowel syndrome, national health insurance research database, real-world evidence

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Authors: Qian Huiya, Feng Lin

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The progressive collapse of reinforced concrete (RC) structures will cause huge casualties and property losses. Therefore, it is necessary to evaluate the ability of structures against progressive collapse accurately. This paper numerically investigated the effect of storey number on the mechanism and quantitative contribution of the Vierendeel action (VA) in progressive collapse under corner column removal scenario. First, finite element (FE) models of multi-storey RC frame structures were developed using LS-DYNA. Then, the accuracy of the modeling technique was validated by test results conducted by the authors. Last, the validated FE models were applied to investigated the structural behavior of the RC frames with different storey numbers from one to six storeys. Results found the multi-storey substructure formed additional plastic hinges at the beam ends near the corner column in the second to top storeys, and at the lower end of the corner column in the first storey. The average ultimate resistance of each storey of the multi-storey substructures were increased by 14.0% to 18.5% compared with that of the single-storey substructure experiencing no VA. The contribution of VA to the ultimate resistance was decreased with the increase of the storey number.

Keywords: progressive collapse, reinforced concrete structure, storey number, Vierendeel action

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Authors: Nizar Ahmad, Mushtaq Ahmad Jadoon, Farhat Ullah

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This study investigates the peace efforts made by Pakhtun’s traditional institution Jirga in conflict-affected communities of Khyber Pakhtunkhwa. Data were collected through a structured interview schedule from a sample of 278 household members in four selected villages of Dir Upper and Dir Lower Districts. A Chi square test was applied to ascertain relationships between Jirga related factors with the state of peace in the study area. It was found that factors such as Jirga regularly conducted meetings (P=. 000), it inflicted punishment upon local militants (P=. 001), ex-combatants were re-integrated through Jirga (P= .000) and Jirga ordered the local the defiant to leave the community had a significant association with state of peace in the area. It is concluded that Jirga system had played a vital role in the peacebuilding process of the area through provision of support to government in peace operation and mobilizing local people for peace in the area. It is suggested that Jirga shall to be the part of peace process and government needs to provide its possible support to members of the Jirga in order to enhance their capacity of peace work.

Keywords: Jirga, peacebuilding, terrorism, traditional mechanism, conflict affect areas

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Authors: Aishwarya Shekhar, Devesh Kumar Srivastava

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Cloud computing has emerged as a promising direction for cost efficient and reliable service delivery across data communication networks. The dynamic location of service facilities and the virtualization of hardware and software elements are stressing the communication networks and protocols, especially when data centres are interconnected through the internet. Although the computing aspects of cloud technologies have been largely investigated, lower attention has been devoted to the networking services without involving IT operating overhead. Cloud computing has enabled elastic and transparent access to infrastructure services without involving IT operating overhead. Virtualization has been a key enabler for cloud computing. While resource virtualization and service abstraction have been widely investigated, networking in cloud remains a difficult puzzle. Even though network has significant role in facilitating hybrid cloud scenarios, it hasn't received much attention in research community until recently. We propose Network as a Service (NaaS), which forms the basis of unifying public and private clouds. In this paper, we identify various challenges in adoption of hybrid cloud. We discuss the design and implementation of a cloud platform.

Keywords: cloud computing, networking, infrastructure, hybrid cloud, open stack, naas

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Authors: Nuttawoot Nupo, Sayan Panma

Abstract:

A semigroup S is said to be a left (right) zero semigroup if S satisfies the equation xy=x (xy=y) for all x,y in S. In addition, the semigroup S is called a left (right) group if S is isomorphic to the direct product of a group and a left (right) zero semigroup. The Cayley digraph Cay(S,A) of a semigroup S with a connection set A is defined to be a digraph with the vertex set S and the arc set E(Cay(S,A))={(x,xa) | x∈S, a∈A} where A is any subset of S. All sets in this research are assumed to be finite. Let D be a digraph together with a vertex set V and an arc set E. Let u and v be two different vertices in V and I a nonempty subset of V. The vertices u and v are said to be independent if (u,v)∉E and (v,u)∉E. The set I is called an independent set of D if any two different vertices in I are independent. The independence number of D is the maximum cardinality of an independent set of D. Moreover, the vertices u and v are said to be path independent if there is no dipath from u to v and there is no dipath from v to u. The set I is called a path independent set of D if any two different vertices in I are path independent. The path independence number of D is the maximum cardinality of a path independent set of D. In this research, we describe a lower bound and an upper bound of the independence number of Cayley digraphs of left groups and right groups. Some examples corresponding to those bounds are illustrated here. Furthermore, the exact value of the path independence number of Cayley digraphs of left groups and right groups are also presented.

Keywords: Cayley digraphs, independence number, left groups, path independence number, right groups

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Authors: Karoliina Nisula, Samuli Pekkola

Abstract:

Business education has been criticized for being too theoretical and distant from business life. Different types of experiential learning environments ranging from manual role-play to computer simulations and enterprise resource planning (ERP) systems have been used to introduce the realistic and practical experience into business learning. Each of these learning environments approaches business learning from a different perspective. The implementations tend to be individual exercises supplementing the traditional courses. We suggest combining them into a business skills laboratory resembling an actual workplace. In this paper, we present a concrete implementation of an ERP-supported business learning environment that is used throughout the first year undergraduate business curriculum. We validate the implementation by evaluating the learning outcomes through the different domains of Bloom’s taxonomy. We use the role-play oriented practice enterprise model as a comparison group. Our findings indicate that using the ERP simulation improves the poor and average students’ lower-level cognitive learning. On the affective domain, the ERP-simulation appears to enhance motivation to learn as well as perceived acquisition of practical hands-on skills.

Keywords: business simulations, experiential learning, ERP systems, learning environments

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Authors: Norhayati Mat Wajid, Abdul Murad Zainal Abidin, Hasila Jarimi, Kamaruzaman Sopian, Adnan Ibrahim, Ahmad Fazlizan, Afif Safwan

Abstract:

Solar-adsorption air-conditioning system (SADCS) is an alternative to the conventional vapor compression system (VCS). SADCS have advantages over VCS system, such as 1) a green cooling technology which utilizes solar energy to drive the adsorption/desorption cycle, 2) can be operated using green refrigerant HFC free pure water, 3) mechanically simpler, and 4) lower operating noise level since it has no moving parts other than the magnetic valves. Several advancements have been achieved in these fields in the last decade, but further research is still needed to escalate this technology to a practical level. Hence, this paper presents a literature survey and a review that add insights into the current state-of-the-art of SADCS technologies with emphasis on the practical researches that were conducted at the laboratory scale and commercial level. In this paper, the performance evaluation of vermiculite as adsorbent material for SADCS in tropical climate discussed in comparison to other adsorbent material such as silica gel.

Keywords: adsorption cooling, solar-assisted cooling, HVAC, tropical climate, solar thermal

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Authors: A. Altomi, A. Alhebshi, M. Rasm, B. Osman

Abstract:

This study explored the application of chitin nanocrystals (ChiNCs), derived from a renewable and environmentally friendly material, as stabilizers for oil-in-water (O/W) emulsions. O/W emulsions are commonly used in various applications but are prone to instability and degradation over time. Instability can occur due to factors such as flocculation, coalescence, and gravitational separation, including creaming and sedimentation, either independently or simultaneously. To produce ChiNCs, chitin powder underwent acid hydrolysis. Transmission electron microscopy (TEM) analysis revealed that ChiNCs exhibited a needle-like morphology, with lengths ranging from 200 to 800 nm and widths ranging from 20 to 80 nm. The surface charge of ChiNCs was negative at pH values above 7 and positive at pH values below 7. The rheological properties of O/W emulsions stabilized by ChiNCs were compared to those stabilized by synthetic surfactants, namely Tween 80 and CTAB. The emulsions stabilized by ChiNCs demonstrated higher yield stress and lower shear viscosity compared to those stabilized by synthetic surfactants. This indicates that ChiNC-stabilized emulsions are more stable and less prone to breakdown. Based on these findings, ChiNCs show promise as an alternative to synthetic surfactants for stabilizing O/W emulsions.

Keywords: chitin nanocrystals, colloidal pickering, emulsion rheology, oil-in-water, synthetic surfactant

Procedia PDF Downloads 62