Search results for: electrostatic force

Authors: Keping Zuo, Foad Kabinejadian, Gideon Praveen Kumar Vijayakumar, Fangsen Cui, Pei Ho, Hwa Liang Leo

Abstract:

Carotid artery stenting (CAS) is the standard procedure for patients with severe carotid stenosis at high risk for carotid endarterectomy (CAE). A major drawback of CAS is the higher incidence of procedure-related stroke compared with traditional open surgical treatment for carotid stenosis - CEA, even with the use of the embolic protection devices (EPD). As the currently available bare metal stents cannot address this problem, our research group developed a novel preferential covered-stent for carotid artery aims to prevent friable fragments of atherosclerotic plaques from flowing into the cerebral circulation, and yet maintaining the flow of the external carotid artery. The preliminary animal studies have demonstrated the potential of this novel covered-stent design for the treatment of carotid atherosclerotic stenosis. The purpose of this study is to evaluate the effect of membrane coating on the stent flexibility in order to improve the clinical performance of our novel covered stents. A total of 21 stents were evaluated in this study: 15 self expanding bare nitinol stents and 6 PTFE-covered stents. 10 of the bare stents were coated with 11%, 16% and 22% Polyurethane(PU), 4%, 6.25% and 11% EE, as well as 22% PU plus 5 μm Parylene. Different laser cutting designs were performed on 4 of the PTFE covert stents. All the stents, with or without the covered membrane, were subjected to a three-point flexural test. The stents were placed on two supports that are 30 mm apart, and the actuator is applying a force in the exact middle of the two supports with a loading pin with radius 2.5 mm. The loading pin displacement change, the force and the variation in stent shape were recorded for analysis. The flexibility of the stents was evaluated by the lumen area preservation at three displacement bending levels: 5mm, 7mm, and 10mm. All the lumen areas in all stents decreased with the increase of the displacement from 0 to 10 mm. The bare stents were able to maintain 0.864 ± 0.015, 0.740 ± 0.025 and 0.597 ± 0.031of original lumen area at 5 mm, 7 mm and 10mm displacement respectively. For covered stents, the stents with EE coating membrane showed the best lumen area preservation (0.839 ± 0.005, 0.7334 ± 0.043 and 0.559 ± 0.014), whereas, the stents with PU and Parylene coating were only 0.662, 0.439 and 0.305. Bending stiffness was also calculated and compared. These results provided optimal material information and it was crucial for enhancing clinical performance of our novel covered stents.

Keywords: carotid artery, covered stent, nonlinear, hyperelastic, stress, strain

Procedia PDF Downloads 295

Authors: Faruk Ortes, Derya Karabulut, Yunus Ziya Arslan

Abstract:

Myoelectric features gathering from musculature environment are considered on a preferential basis to perceive muscle activation and control human arm prostheses according to recent experimental researches. EMG (electromyography) signal based human arm prostheses have shown a promising performance in terms of providing basic functional requirements of motions for the amputated people in recent years. However, these assistive devices for neurorehabilitation still have important limitations in enabling amputated people to perform rather sophisticated or functional movements. Surface electromyogram (EMG) is used as the control signal to command such devices. This kind of control consists of activating a motion in prosthetic arm using muscle activation for the same particular motion. Extraction of clear and certain neural information from EMG signals plays a major role especially in fine control of hand prosthesis movements. Many signal processing methods have been utilized for feature extraction from EMG signals. The specific objective of this study was to compare widely used time domain features of EMG signal including integrated EMG(IEMG), root mean square (RMS) and waveform length(WL) for prediction of externally applied forces to human hands. Obtained features were classified using artificial neural networks (ANN) to predict the forces. EMG signals supplied to process were recorded during only type of muscle contraction which is isometric and isotonic one. Experiments were performed by three healthy subjects who are right-handed and in a range of 25-35 year-old aging. EMG signals were collected from muscles of the proximal part of the upper body consisting of: biceps brachii, triceps brachii, pectorialis major and trapezius. The force prediction results obtained from the ANN were statistically analyzed and merits and pitfalls of the extracted features were discussed with detail. The obtained results are anticipated to contribute classification process of EMG signal and motion control of powered human arm prosthetics control.

Keywords: assistive devices for neurorehabilitation, electromyography, feature extraction, force estimation, human arm prosthesis

Procedia PDF Downloads 367

Authors: A. Metioui

Abstract:

Research related to the student’s conceptual difficulties in sciences, particularly in the field of physics, are relatively numerous. In this work, we will analyze the results of qualitative research conducted with 80 elementary preservice teachers from Quebec in Canada on their understandings after studying the free fall bodies. First, we will illustrate the paper-pencil questionnaire built for this purpose. Then we will give the analysis of the experimental data. The results show that, even though there is a continuing physics education, many misconceptions persist despite the teaching provided.

Keywords: pre-service teachers, elementary school, conceptual difficulties, free fall bodies

Procedia PDF Downloads 126

Authors: Niyti, Aman Deep, Rajesh Kharab, Sahila Chopra, Raj. K. Gupta

Abstract:

Relatively long-lived transactinide elements (i.e., elements with atomic number Z≥104) up to Z = 108 have been produced in nuclear reactions between low Z projectiles (C to Al) and actinide targets. Cross sections have been observed to decrease steeply with increasing Z. Recently, production cross sections of several picobarns have been reported for comparatively neutron-rich nuclides of 112 through 118 produced via hot fusion reactions with 48Ca and actinide targets. Some of those heavy nuclides are reported to have lifetimes on the order of seconds or longer. The relatively high cross sections in these hot fusion reactions are not fully understood and this has renewed interest in systematic studies of heavy-ion reactions with actinide targets. The main aim of this work is to understand the dynamics hot fusion reactions 18O+ 248Cm and 22Ne+244Pu (carried out at RIKEN and TASCA respectively) using the collective clusterization technique, carried out by undertaking the decay of the compound nucleus 266Rf∗ into 4n, 5n and 6n neutron evaporation channels. Here we extend our earlier study of the excitation functions (EFs) of 266Rf∗, formed in fusion reaction 18O+248Cm, based on Dynamical Cluster-decay Model (DCM) using the pocket formula for nuclear proximity potential, to the use of other nuclear interaction potentials derived from Skyrme energy density formalism (SEDF) based on semiclassical extended Thomas Fermi (ETF) approach and also study entrance channel effects by considering the synthesis of 266Rf* in 22Ne+244Pu reaction. The Skyrme forces used are the old force SIII, and new forces GSkI and KDE0(v1). Here, the EFs for the production of 260Rf, 261Rf and 262Rf isotope via 6n, 5n and 4n decay channel from the 266Rf∗ compound nucleus are studied at Elab = 88.2 to 125 MeV, including quadrupole deformations β2i and ‘hot-optimum’ orientations θi. The calculations are made within the DCM where the neck-length ∆R is the only parameter representing the relative separation distance between two fragments and/or clusters Ai which assimilates the neck formation effects.

Keywords: entrance channel effects, fusion reactions, skyrme force, superheavy nucleus

Procedia PDF Downloads 253

Authors: El-Said I. El-Shafey, Syeda Naheed F. Ali, Saleh S. Al-Busafi, Haider A. J. Al-Lawati

Abstract:

Date palm leaflets were utilized as a precursor for activated carbon (AC) preparation using KOH activation. AC produced was oxidized using nitric acid producing oxidized activated carbon (OAC). OAC that possesses acidic surface was surface functionalized to produce basic activated carbons using linear diamine compounds (ethylene diamine and propylene diamine). OAC was also functionalized to produce hydrophobic activated carbons using ethylamine (EA) and aniline (AN). Dehydrated carbon was also prepared from date palm leaflets using sulfuric acid dehydration/ oxidation and was surface functionalized in the same way as AC. Nitric acid oxidation was not necessary for DC as it is acidic carbon. The surface area of AC is high (823 m2/g) with microporosity domination, however, after oxidation and surface functionalization, both the surface area and surface microporosity decrease tremendously. DC surface area was low (15 m2/g) with mesoporosity domination. Surface functionalization has decreased the surface area of activated carbons. FTIR spectra show that -COOH group on DC and OAC almost disappeared after surface functionalization. The surface chemistry of all carbons produced was tested for pHzpc, basic sites, boehm titration, thermogravimetric analysis and zeta potential measurement. Scanning electron microscopy and energy dispersive spectroscopy in addition to CHN elemental analysis were also carried out. DC and OAC possess low pHzpc and high surface functionality, however, basic and hydrophobic carbons possess high pHzpc and low surface functionality. The different behavior of carbons is related to their different surface chemistry. Methylene blue adsorption was found to be faster on hydrophobic carbons based on AC and DC. The Larger adsorption capacity of methylene blue was found for hydrophobic carbons. Dominating adsorption forces of methylene blue varies from carbon to another depending on its surface nature. Sorption forces include hydrophobic forces, H-bonding, electrostatic interactions and van der Waals forces.

Keywords: carbon, acidic, basic, hydrophobic

Procedia PDF Downloads 285

Authors: Gabriela-Andreea Despescu, Mădălina-Elena Mavrodin, Gheorghe Lăzăroiu, Florin Adrian Grădinaru

Abstract:

The purpose of this paper is to contribute to the enhancement of a hydroelectric plant protection by coordinating protection measures and existing security and introducing new measures under a risk management process. Also, the plan identifies key critical elements of a hydroelectric plant, from its level vulnerabilities and threats it is subjected to in order to achieve the necessary protection measures to reduce the level of risk.

Keywords: critical infrastructure, risk analysis, critical infrastructure protection, vulnerability, risk management, turbine, impact analysis

Procedia PDF Downloads 547

Authors: Tichaona Nharingo, Hope Tauya, Mambo Moyo

Abstract:

Wood ash has been demonstrated to have favourable adsorption capacity for heavy metal ions but suffers the application problem of difficult to separate/isolate from the batch adsorption systems. Fabrication of wood ash beads using multifunctional group and non-toxic carbohydrate, alginate, may improve the applicability of wood ash in environmental pollutant remediation. In this work, alginate-wood ash beads (AWAB) were fabricated and applied to the removal of cadmium ions from aqueous systems. The beads were characterized by FTIR, TGA/DSC, SEM-EDX and their pHZPC before and after the adsorption of Cd(II) ions. Important adsorption parameters i.e. pH, AWAB dosage, contact time and ionic strength were optimized and the effect of initial concentration of Cd(II) ions to the adsorption process was established. Adsorption kinetics, adsorption isotherms, adsorption mechanism and application of AWAB to real water samples spiked with Cd(II) ions were ascertained. The composite adsorbent was characterized by a heterogeneous macro pore surface comprising of metal oxides, multiple hydroxyl groups and carbonyl groups that were involved in electrostatic interaction and Lewis acid-base interactions with the Cd(II) ions. The pseudo second order and the Freundlich isotherm models best fitted the adsorption kinetics and isotherm data respectively suggesting chemical sorption process and surface heterogeneity. The presence of Pb(II) ions inhibited the adsorption of Cd(II) ions (reduced by 40 %) attributed to the competition for the adsorption sites. The Cd(II) loaded beads could be regenerated using 0.1 M HCl and could be applied to four sorption-desorption cycles without significant loss in its initial adsorption capacity. The high maximum adsorption capacity, stability, selectivity and reusability of AWAB make the adsorbent ideal for application in the removal of Cd(II) ions from real water samples. Column type adsorption experiments need to be explored to establish the potential of the adsorbent in removing Cd(II) ions using continuous flow systems.

Keywords: adsorption, Cd(II) ions, regeneration, wastewater, wood ash-alginate beads

Procedia PDF Downloads 245

Authors: Sameut Bouhaik Mostafa

Abstract:

Information Act is the Canadian law gives the right of access to information for the institution of government. It declares the availability of government information to the public, but that exceptions should be limited and the necessary right of access to be specific, and also states the need to constantly re-examine the decisions on the disclosure of any government information independently from the government. By 1982, it enacted a dozen countries, including France, Denmark, Finland, Sweden, the Netherlands and the United States (1966) newly legally to access the information. It entered access to Canadian information into force of the Act of 1983, under the government of Pierre Trudeau, allowing Canadians to recover information from government files, and the development of what can be accessed from the information, and the imposition of timetables to respond. It has been applied by the Information Commissioner in Canada.

Keywords: law, information, management, legal

Procedia PDF Downloads 415

Authors: M. H. Ahmadi, A. Mortazavi, H. Zarei

Abstract:

Several authors have described the main mechanism of formation of cracks in the segment lining during the construction of tunnels with tunnel boring machines. A comprehensive analysis of segmental lining joints may help to guarantee a safe construction during Tunneling and serviceable stages. The most frequent types of segment damage are caused by a condition of uneven segment matching due to contact deficiencies. This paper investigated the interaction mechanism of precast concrete lining joints in tunnels. The Discrete Element Method (DEM) was used to analyze a typical segmental lining model consisting of six segment rings. In the analyses, typical segmental lining design parameters of the Ghomrood water conveyance tunnel, Iran were employed in the study. In the conducted analysis, the worst-case scenario of loading faced during the boring of Ghomrood tunnel was considered. This was associated with the existence of a crushed zone dipping at 75 degree at the location of the key segment. In the analysis, moreover, the effect of changes in horizontal stress ratio on the loads on the segment was assessed. The boundary condition associated with K (ratio of the horizontal to the vertical stress) values of 0.5, 1, 1.5 and 2 were applied to the model and separate analysis was conducted for each case. Important parameters such as stress, moments, and displacements were measured at joint locations and the surrounding rock. Accordingly, the segment joint interactions were assessed and analyzed. Moreover, rock mass properties of the Ghomrood in Ghom were adopted. In this study, the load acting on segments joints are included a crushed zone stratum force that intersect tunnel with 75 slopes in the location of the key segment, gravity force of segments and earth pressures. A numerical investigation was used for different coefficients of stress concentration of 0.5, 1, 1.5, 2 and different geological conditions of saturated crushed zone under the critical scenario. The numerical results also demonstrate that maximum bending moments in longitudinal joints occurred for crushed zone with the weaken strengths (Sandstone). Besides that, increasing the load in segment-stratum interfaces affected radial stress in longitudinal joints and finally the opening of joints occurred.

Keywords: joint, interface, segment, contact

Procedia PDF Downloads 258

Authors: Florian Keipert, Hagen Schmitd

Abstract:

The size selective separation of different species in a microfluidic system is an actual task in biological or medical research. Former works dealt with the utilisation of the acoustic radiation force (ARF) caused by a plane travelling Surface Acoustic Wave (tSAW). In literature the ARF is described by a dimensionless parameter κ, depending on the wavelength and the particle diameter. To our knowledge research was done for values 0.2 < κ < 5.8 showing that the ARF is dominating the acoustic streaming force (ASF) for κ > 1.2. As a consequence the particle separation is limited by κ. In addition the dependence on the electrical power level was examined but only for κ > 1 pointing out an increased particle deflection for higher electrical power levels. Nevertheless a detailed study on the ASF and ARF especially for κ < 1 is still missing. In our setup we used a tSAW with a wavelength λ = 90 µm and 3 µm PS particles corresponding to κ = 0.3. Herewith the influence of the applied electrical power level on the particle deflection in a polydimethylsiloxan micro channel was investigated. Our results show an increased particle deflection for an increased electrical power level, which coincides with the reported results for κ > 1. Therefore particle separation is in contrast to literature also possible for lower κ values. Thereby the experimental setup can be generally simplified by a coordinated electrical power level for the specific particle size. Furthermore this raises the question of whether this particle deflection is caused only by the ARF as adopted so far or by the ASF or the sum of both forces. To investigate this fact a 0% - 24% saline solution was used and thus the mismatch between the compressibility of the PS particle and the working fluid could be changed. Therefore it is possible to change the relative strength between ARF and ASF and consequently the particle deflection. We observed a decreasing in the particle deflection for an increased NaCl content up to a 12% saline solution and subsequently an increasing of the particle deflection. Our observation could be explained by the acoustic contrast factor Φ, which depends on the compressibility mismatch. The compressibility of water is increased by the NaCl and the range of a 0% - 24% saline solution covers the PS particle compressibility. Hence the particle deflection reaches a minimum value for the accordance between compressibility of PS particle and saline solution. This minimum value can be estimated as the particle deflection only caused by the ASF. Knowing the particle deflection due to the ASF the particle deflection caused by the ARF can be calculated and thus finally the relation between both forces. Concluding, the particle deflection and therefore the size selective particle separation generated by a tSAW can be achieved for values κ < 1, simplifying actual setups by adjusting the electrical power level. Beyond we studied for the first time the relative strength between ARF and ASF to characterise the particle deflection in a microchannel.

Keywords: ARF, ASF, particle separation, saline solution, tSAW

Procedia PDF Downloads 258

Authors: Chengcao Sun, Cuili Yang, Shujun Li, Ruilin Xue, Liang Wang, Yongyong Xi, Dejia Li

Abstract:

Backgrounds: Sulforaphane, one of the most important isothiocyanates in the human diet, is known to have chemopreventive and antioxidant activities in different tissues via activation of NF-E2-related factor 2 (Nrf2)-mediated induction of antioxidant/phase II enzymes, such as heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase 1 (NQO1). However, its effects on muscular dystrophy remain unknown. This work was undertaken to evaluate the effects of Sulforaphane on Duchenne muscular dystrophy (DMD). Methods: 4-week-old mdx mice were treated with SFN by gavage (2 mg/kg body weight per day) for 8 weeks. Blood was collected from eye socket every week, and tibial anterior, extensor digitorum longus, gastrocnemius, soleus, triceps brachii muscles and heart samples were collected after 8-week gavage. Force measurements and mice exercise capacity assays were detected. GSH/GSSG ratio, TBARS, CK and LDH levels were analyzed by spectrophotometric methods. H&E staining was used to analyze histological and morphometric of skeletal muscles of mdx mice, and Evas blue dye staining was made to detect sarcolemmal integrity of mdx mice. Further, the role of Sulforaphane on Nrf2/ARE signaling pathway was analyzed by ELISA, western blot and qRT-PCR. Results: Our results demonstrated that SFN treatment increased the expression and activity of muscle phase II enzymes NQO1 and HO-1 with Nrf2 dependent manner. SFN significantly increased skeletal muscle mass, muscle force (~30%), running distance (~20%) and GSH/GSSG ratio (~3.2 folds) of mdx mice, and decreased the activities of plasma creatine phosphokinase (CK) (~45%) and lactate dehydrogenase (LDH) (~40%), gastrocnemius hypertrophy (~25%), myocardial hypertrophy (~20%) and MDA levels (~60%). Further, SFN treatment also reduced the central nucleation (~40%), fiber size variability, inflammation and improved the sarcolemmal integrity of mdx mice. Conclusions: Collectively, these results show that SFN can improve muscle function, pathology and protect dystrophic muscle from oxidative damage in mdx mice through Nrf2 signaling pathway, which indicate Nrf2 may have clinical implications for the treatment of patients with muscular dystrophy.

Keywords: sulforaphane, duchenne muscular dystrophy, Nrf2, oxidative stress

Procedia PDF Downloads 322

Authors: Desmond Agbolade Ademola

Abstract:

This work aimed to introduce a theory, called Guided Energy Theory of a particle that answered questions that arise from quantum foundation, quantum mechanics theory, and interpretation such as: what is nature of wavefunction? Is mathematical formalism of wavefunction correct? Does wavefunction collapse during measurement? Do quantum physical entanglement and many world interpretations really exist? In addition, is there uncertainty in the physical reality of our nature as being concluded in the Quantum theory? We have been able to show by the fundamental analysis presented in this work that the way quantum mechanics theory, and interpretation describes nature is not correlated with physical reality. Because, we discovered amongst others that, (1) Guided energy theory of a particle fundamentally provides complete physical observable series of quantized measurement of a particle momentum, force, energy e.t.c. in a given distance and time.In contrast, quantum mechanics wavefunction describes that nature has inherited probabilistic and indeterministic physical quantities, resulting in unobservable physical quantities that lead to many worldinterpretation.(2) Guided energy theory of a particle fundamentally predicts that it is mathematically possible to determine precise quantized measurementof position and momentum of a particle simultaneously. Because, there is no uncertainty in nature; nature however naturally guides itself against uncertainty. Contrary to the conclusion in quantum mechanics theory that, it is mathematically impossible to determine the position and the momentum of a particle simultaneously. Furthermore, we have been able to show by this theory that, it is mathematically possible to determine quantized measurement of force acting on a particle simultaneously, which is not possible on the premise of quantum mechanics theory. (3) It is evidently shown by our theory that, guided energy does not collapse, only describes the lopsided nature of a particle behavior in motion. This pretty offers us insight on gradual process of engagement - convergence and disengagement – divergence of guided energy holders which further highlight the picture how wave – like behavior return to particle-like behavior and how particle – like behavior return to wave – like behavior respectively. This further proves that the particles’ behavior in motion is oscillatory in nature. The mathematical formalism of Guided energy theory shows that nature is certainty whereas the mathematical formalism of Quantum mechanics theory shows that nature is absolutely probabilistics. In addition, the nature of wavefunction is the guided energy of the wave. In conclusion, the fundamental mathematical formalism of Quantum mechanics theory is wrong.

Keywords: momentum, physical entanglement, wavefunction, uncertainty

Procedia PDF Downloads 295

Authors: Javier Perez-Vaquero, Katryn Junker, Volker Lammers, Petra Foerst

Abstract:

There is increasing importance to accelerate the transition to sustainable food systems by including environmentally friendly technologies. Our work focuses on protein enrichment and fractionation of agricultural side streams by dry triboelectrostatic separation technology. Materials are fed in particulate form into a system dispersed in a highly turbulent gas stream, whereby the high collision rate of particles against surfaces and other particles greatly enhances the electrostatic charge build-up over the particle surface. A subsequent step takes the charged particles to a delimited zone in the system where there is a highly uniform, intense electric field applied. Because the charge polarity acquired by a particle is influenced by its chemical composition, morphology, and structure, the protein-rich and fiber-rich particles of the starting material get opposite charge polarities, thus following different paths as they move through the region where the electric field is present. The output is two material fractions, which differ in their respective protein content. One is a fiber-rich, low-protein fraction, while the other is a high-protein, low-fiber composition. Prior to testing, materials undergo a milling process, and some samples are stored under controlled humidity conditions. In this way, the influence of both particle size and humidity content was established. We used two oilseed meals: lupine and rapeseed. In addition to a lab-scale separator to perform the experiments, the triboelectric separation process could be successfully scaled up to a mid-scale belt separator, increasing the mass feed from g/sec to kg/hour. The triboelectrostatic separation technology opens a huge potential for the exploitation of so far underutilized alternative protein sources. Agricultural side-streams from cereal and oil production, which are generated in high volumes by the industries, can further be valorized by this process.

Keywords: bench-scale processing, dry separation, protein-enrichment, triboelectrostatic separation

Procedia PDF Downloads 190

Authors: Abtehal Y. Anaas, Mohd. Nazmi Bin Abd. Manap

Abstract:

Meat Tenderness is one of the most important factors affecting consumers' assessment of meat quality. Variation in meat tenderness is genetically controlled and varies among breeds, and it is also influenced by environmental factors that can affect its creation during rigor mortis and postmortem. The final postmortem meat tenderization relies on the extent of proteolysis of myofibrillar proteins caused by the endogenous activity of the proteolytic calpain system. This calpain system includes different calcium-dependent cysteine proteases, and an inhibitor, calpastatin. It is widely accepted that in farm animals including chickens, the μ-calpain gene (CAPN1) is a physiological candidate gene for meat tenderness. This study aimed to identify the association of single nucleotide polymorphism (SNP) markers in the CAPN1 gene with the tenderness of chicken breast meat from two Malaysian native and commercial broiler breed crosses. Ten, five months old native chickens and ten, 42 days commercial broilers were collected from the local market and breast muscles were removed two hours after slaughter, packed separately in plastic bags and kept at -20ºC for 24 h. The tenderness phenotype for all chickens’ breast meats was determined by Warner-Bratzler Shear Force (WBSF). Thawing and cooking losses were also measured in the same breast samples before using in WBSF determination. Polymerase chain reaction (PCR) was used to identify the previously reported C7198A and G9950A SNPs in the CAPN1 gene and assess their associations with meat tenderness in the two breeds. The broiler breast meat showed lower shear force values and lower thawing loss rates than the native chickens (p<0.05), whereas there were similar in the rates of cooking loss. The study confirms some previous results that the markers CAPN1 C7198A and G9950A were not significantly associated with the variation in meat tenderness in chickens. Therefore, further study is needed to confirm the functional molecular mechanism of these SNPs and evaluate their associations in different chicken populations.

Keywords: CAPNl, chicken, meat tenderness, meat quality, SNPs

Procedia PDF Downloads 245

Authors: Osman Acar

Abstract:

Sun tracking systems are the systems following the sun ray by a right angle or by predetermined certain angle. In this study, we used theoretical trajectory of sun for latitude of central Anatolia in Turkey. A two degree of freedom spherical mechanism was designed to have a large workspace able to follow the sun's theoretical motion by the right angle during the whole year. An inverse kinematic analysis was generated to find the positions of mechanism links for the predicted trajectory. Force and torque analysis were shown for the first day of the year.

Keywords: sun tracking, theoretical sun trajectory, spherical mechanism, inverse kinematic analysis

Procedia PDF Downloads 419

Authors: Juliet F. Poujol, Jeff John Tanner, Christophe Fournier

Abstract:

Employers desire a favorable brand as an employer. This research considers whether motivation theory is applied to identify universally desirable employer brand elements. Based on data from a website where employees give their opinion about their employer (N=200), this research examines what salespeople found positive and negative about their job. Results show that traditional motivators like opportunities of advancement, and 'hygiene' factors such as benefits and work conditions are a source of satisfaction for salespeople. We also found differences by sectors. Implications are related to sales force recruitment and management.

Keywords: employer brand, motivation, qualitative study, salespeople

Procedia PDF Downloads 384

Authors: A. Fakhri Makram, Marwa S. Alwazni, Al-Douri Yarub, Evan T. Salim, Hashim Uda, Chin C. Woei

Abstract:

Lithium niobate (LiNbO₃) nanostructures are prepared on quartz substrate by the sol-gel method. They have been deposited with different molarity concentration and annealed at 500°C. These samples are characterized and analyzed by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM). The measured results showed an importance increasing in molarity concentrations that indicate the structure starts to become crystal, regular, homogeneous, well crystal distributed, which made it more suitable for optical waveguide application.

Keywords: lithium niobate, morphological properties, thin film, pechini method, XRD

Procedia PDF Downloads 446

Authors: Dhiflaoui Hafedh, Khlifi Kaouther, Ben Cheikh Larbi Ahmed

Abstract:

Monolayer and multilayer coatings of CrN and AlCrN deposited on 100Cr6 (AISI 52100) substrate by PVD magnetron sputtering system. The micro structures of the coatings were characterized using atomic force microscopy (AFM). The AFM analysis revealed the presence of domes and craters which are uniformly distributed over all surfaces of the various layers. Nano indentation measurement of CrN coating showed maximum hardness (H) and modulus (E) of 14 GPa and 240 GPa, respectively. The measured H and E values of AlCrN coatings were found to be 30 GPa and 382 GPa, respectively. The improved hardness in both the coatings was attributed mainly to a reduction in crystallite size and decrease in surface roughness. The incorporation of Al into the CrN coatings has improved both hardness and Young’s modulus.

Keywords: CrN, AlCrN coatings, hardness, nanoindentation

Procedia PDF Downloads 557

Authors: S. S. Dol

Abstract:

Improvement in vehicle efficiency can reduce global fossil fuels consumptions. For that sole reason, Shell Global Corporation introduces Shell Eco-marathon where student teams require to design, build and test energy-efficient vehicles. Hence, this paper will focus on design processes and the development of a fuel economic vehicle which satisfying the requirements of the competition. In this project, three components are designed and analyzed, which are the body, chassis and powertrain of the vehicle. Optimum design for each component is produced through simulation analysis and theoretical calculation in which improvement is made as the project progresses.

Keywords: energy efficient, drag force, chassis, powertrain

Procedia PDF Downloads 335

Authors: Desiree Di Marco

Abstract:

The aim of this work is to show through the lens of art first which kind of reality was the one represented through fascist maps, and second to study the impact of the fascist regime’s cartography (FRC) on observers eye’s. In this study, it is assumed that the FRC’s representation of reality was simplified, timeless, and even a-spatial because it underrates the concept of territoriality. Cubism and Picasso’s paintings will be used as counter-examples to mystify fascist cartography’s ideological assumptions. The difference between the gaze of an observer looking at the surface of a fascist map and the gaze of someone observing a Picasso painting is impressive. Because there is always something dark, hidden, behind and inside a map, the world of fascist maps was a world built starting from the observation of a “window” that distorted reality and trapped the eyes of the observers. Moving across the map, they seem as if they were hypnotized. Cartohypnosis is the state in which the observer finds himself enslaved by the attractive force of the map, which uses a sort of “magic” geography, a geography that, by means of symbolic language, never has as its primary objective the attempt to show us reality in its complexity, but that of performing for its audience. Magical geography and hypnotic cartography in fascism blended together, creating an almost mystical, magical relationship that demystified reality to reduce the world to a conquerable space. This reduction offered the observer the possibility of conceiving new dimensions: of the limit, of the boundary, elements with which the subject felt fully involved and in which the aesthetic force of the images demonstrated all its strength. But in the early 20th century, the combination of art and cartography gave rise to new possibilities. Cubism which, more than all the other artistic currents showed us how much the observation of reality from a single point of view falls within dangerous logic, is an example. Cubism was an artistic movement that brought about a profound transformation in pictorial culture. It was not only a revolution of pictorial space, but it was a revolution of our conception of pictorial space. Up until that time, men and women were more inclined to believe in the power of images and their representations. Cubist painters rebelled against this blindness by claiming that art must always offer an alternative. Indeed the contribution of this work is precisely to show how art can be able to provide alternatives to even the most horrible regimes and the most atrocious human misfortunes. It also enriches the field of cartography because it "reassures" it by showing how much good it can be for cartography if also for other disciplines come close. Only in this way researcher can increase the chances for the cartography of a greater diffusion at the academic level.

Keywords: cartography, Picasso, fascism, culture

Procedia PDF Downloads 64

Authors: Seema Sant

Abstract:

In the 21st century were four generation workforces are working, it’s crucial for organizations to build talent management strategy, as tech-savvy Gen Y has entered the work force. They are more connected to each other than ever – through the internet enabled Social media networks Social media has become important in today’s world. The users of such Social media sites have increased in multiple. From sharing their opinion for a brand/product to researching a company before going for an interview, making a conception about a company’s culture or following a Company’s updates due to sheer interest or for job vacancy, Work force today is constantly in touch with social networks. Thus corporate world has rightly realized its potential uses for business purpose. Companies now use social media for marketing, advertising, consumer survey, etc. For HR professionals, it is used for networking and connecting to the Talent pool- through Talent Community. Social recruiting is the process of sourcing or hiring candidates through the use of social sites such as LinkedIn, Facebook Twitter which provide them with an array of information about potential employee; this study represents an exploratory investigation on the role of social networking sites in recruitment. The primarily aim is to analyze the factors that can enhance the channel of recruitment used by of the recruiter with specific reference to the IT organizations in Mumbai, India. Particularly, the aim is to identify how and why companies use social media to attract and screen applicants during their recruitment processes. It also examines the advantages and limitations of recruitment through social media for employers. This is done by literature review. Further, the papers examine the recruiter impact and understand the various opportunities which have created due to technology, thus, to analyze and examine these factors, both primary, as well as secondary data, are collected for the study. The primary data are gathered from five HR manager working in five top IT organizations in Mumbai and 100 HR consultants’ i.e., recruiter. The data was collected by conducting a survey and supplying a closed-ended questionnaire. A comprehension analysis of the study is depicted through graphs and figures. From the analysis, it was observed that there exists a positive relationship between the level of employee recruited through social media and their organizational commitment. Finally the findings show that company’s i.e. recruiters are currently using social media in recruitment, but perhaps not as effective as they could be. The paper gives recommendations and conditions for success that can help employers to make the most out of social media in recruitment.

Keywords: recruitment, social media, social sites, workforce

Procedia PDF Downloads 179

Authors: Abdelkader Nouri, M’hamed Bouslama, Faouzi Saidi, Hassan Maaref, Michel Gendry

Abstract:

Self-organized InAs quantum dots (QDs) have been grown on 3,1% InP (110) lattice mismatched substrate by Solid Source Molecular Beam Epitaxy (SSMBE). Stranski-Krastanov mode growth has been used to create self-assembled 3D islands on InAs wetting layer (WL). The optical quality depending on the temperature and power is evaluated. In addition, Atomic Force Microscopy (AFM) images shows inhomogeneous island dots size distribution due to temperature coalescence. The quantum size effect was clearly observed through the spectra photoluminescence (PL) shape.

Keywords: AFM, InAs QDs, PL, SSMBE

Procedia PDF Downloads 686

Authors: Wenxue Xu

Abstract:

Fluid resistance damper is an important damping element to attenuate vehicle vibration. It converts vibration energy into thermal energy dissipation through oil throttling. It is a typical fluid-solid-heat coupling problem. A complete three-dimensional flow-structure-thermal coupling dynamics simulation model of a gas-filled fluid-resistance damper was established. The flow-condition-based interpolation (FCBI) method and direct coupling calculation method, the unit's FCBI-C fluid numerical analysis method and iterative coupling calculation method are used to achieve the damper dynamic response of the piston rod under sinusoidal excitation; the air chamber inflation pressure, spring compression characteristics, constant flow passage cross-sectional area and oil parameters, etc. The system parameters, excitation frequency, and amplitude and other excitation parameters are analyzed and compared in detail for the effects of differential pressure characteristics, velocity characteristics, flow characteristics and dynamic response of valve opening, floating piston response and piston rod output force characteristics. Experiments were carried out on some simulation analysis conditions. The results show that the node-based FCBI (flow-condition-based interpolation) fluid numerical analysis method and direct coupling calculation method can better guarantee the conservation of flow field calculation, and the calculation step is larger, but the memory is also larger; if the chamber inflation pressure is too low, the damper will become cavitation. The inflation pressure will cause the speed characteristic hysteresis to increase, and the sealing requirements are too strict. The spring compression characteristics have a great influence on the damping characteristics of the damper, and reasonable damping characteristic needs to properly design the spring compression characteristics; the larger the cross-sectional area of the constant flow channel, the smaller the maximum output force, but the more stable when the valve plate is opening.

Keywords: damper, fluid-structure-thermal coupling, heat generation, heat transfer

Procedia PDF Downloads 144

Authors: J. Cecrdle

Abstract:

This paper deals with the whirl flutter of the turboprop aircraft structures. It is focused on the influence of the blade lift span-wise distribution on the whirl flutter stability. Firstly it gives the overall theoretical background of the whirl flutter phenomenon. After that the propeller blade forces solution and the options of the blade lift modelling are described. The problem is demonstrated on the example of a twin turboprop aircraft structure. There are evaluated the influences with respect to the propeller aerodynamic derivatives and finally the influences to the whirl flutter speed and the whirl flutter margin respectively.

Keywords: aeroelasticity, flutter, propeller blade force, whirl flutter

Procedia PDF Downloads 536

Authors: Ehan Sabah Shukri, Wirachman Wisnoe

Abstract:

Numerical study is performed to investigate the temperature distribution in an annular diffuser fitted with helical tape hub. Different pitches (Y = 20 mm, and Y = 30 mm) for the helical tape are studied with different heights (H = 20 mm, 22 mm, and 24 mm) to be compared. The geometry of the annular diffuser and the inlet condition for both hub arrangements are kept constant. The result obtains that using helical tape insert with different pitches and different heights will force the temperature to distribute in a helical direction; however the use of helical tape hub with height (H = 22 mm) for both pitches enhance the temperature distribution in a good manner.

Keywords: helical tape, divergent fluid flow, temperature distribution, swirl flow, CFD

Procedia PDF Downloads 448

Authors: Long Kim Vu, Ban Dang Nguyen

Abstract:

In this paper, the finite element method (FEM) is utilized to simulate the comprehensive process including tightening, releasing and self-loosening of a bolt joint under transverse vibration. Following to the accurate geometry of helical threads, an absolutely hexahedral meshing is implemented. The accuracy of simulation process is verified and validated by comparison with the experimental results on clamping force-vibration relationship, which shows the sufficient correlation. Further analysis with different amplitude and frequency of transverse vibration is done to determine the dominant factor inducing the failure.

Keywords: bolt self-loosening, contact state, finite element method, FEM, helical thread modeling

Procedia PDF Downloads 202

Authors: Abdelhak Nouri

Abstract:

Europium doped zinc oxide nanocolumns (ZnO:Eu) were deposited on indium tin oxide (ITO) substrate from an aqueous solution of 10⁻³M Zn(NO₃)₂ and 0.5M KNO₃ with different concentration of europium ions. The deposition was performed in a classical three-electrode electrochemical cell. The structural, morphology and optical properties have been characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM). The XRD results show high quality of crystallite with preferential orientation along c-axis. SEM images speculate ZnO: Eu has nanocolumnar form with hexagonal shape. The diameter of nanocolumns is around 230 nm. Furthermore, it was found that tail of crystallite, roughness, and band gap energy is highly influenced with increasing Eu ions concentration. The average grain size is about 102 nm to 125 nm.

Keywords: deterioration lattice, doping, nanostructures, Eu:ZnO

Procedia PDF Downloads 177

Authors: Todor N. Penchev, Dimitar N. Karastoianov, Stanislav D. Gyoshev

Abstract:

For compacting of iron powder are used hydraulic presses and high velocity hammers. In this paper are presented initial research on application of an innovative powder compacting method, which uses a hammer working with controlled impact. The results show that by this method achieves the reduction of rebounds and improve efficiency of impact, compared with a high-speed compacting. Depending on the power of the engine (industrial rocket engine), this effect may be amplified to such an extent as to obtain a impact without rebound (sticking impact) and in long-time action of the impact force.

Keywords: powder metallurgy, impact, iron powder compacting, rocket engine

Procedia PDF Downloads 521

Authors: Kai-Chieh Lin, Chih-Fu Wu, Hsiang Ling Hsu, Yung-Hsiang Tu, Chia-Chen Wu

Abstract:

With the rapid development of computer technology, the design of computers and keyboards moves towards a trend of slimness. The change of mobile input devices directly influences users’ behavior. Although multi-touch applications allow entering texts through a virtual keyboard, the performance, feedback, and comfortableness of the technology is inferior to traditional keyboard, and while manufacturers launch mobile touch keyboards and projection keyboards, the performance has not been satisfying. Therefore, this study discussed the design factors of slim pressure-sensitive keyboards. The factors were evaluated with an objective (accuracy and speed) and a subjective evaluation (operability, recognition, feedback, and difficulty) depending on the shape (circle, rectangle, and L-shaped), thickness (flat, 3mm, and 6mm), and force (35±10g, 60±10g, and 85±10g) of the keyboard. Moreover, MANOVA and Taguchi methods (regarding signal-to-noise ratios) were conducted to find the optimal level of each design factor. The research participants, by their typing speed (30 words/ minute), were divided in two groups. Considering the multitude of variables and levels, the experiments were implemented using the fractional factorial design. A representative model of the research samples were established for input task testing. The findings of this study showed that participants with low typing speed primarily relied on vision to recognize the keys, and those with high typing speed relied on tactile feedback that was affected by the thickness and force of the keys. In the objective and subjective evaluation, a combination of keyboard design factors that might result in higher performance and satisfaction was identified (L-shaped, 3mm, and 60±10g) as the optimal combination. The learning curve was analyzed to make a comparison with a traditional standard keyboard to investigate the influence of user experience on keyboard operation. The research results indicated the optimal combination provided input performance to inferior to a standard keyboard. The results could serve as a reference for the development of related products in industry and for applying comprehensively to touch devices and input interfaces which are interacted with people.

Keywords: input performance, mobile device, slim keyboard, tactile feedback

Procedia PDF Downloads 299

Authors: Ariadna Manresa, Ines Ferrer

Abstract:

Introduction: Ultrasonic moulding process (USM) is a recent injection technology used to manufacture micro components. It is able to melt small amounts of material so the waste of material is certainly reduced comparing to microinjection molding. This is an important advantage when the materials are expensive like medical biopolymers. Micro-scaled components are involved in a variety of uses, such as biomedical applications. It is required replication fidelity so it is important to stabilize the process and minimize the variability of the responses. The aim of this research is to investigate the influence of the main process parameters on the filling behaviour, the dimensional accuracy and the cavity pressure when a micro-plate is manufactured by biomaterials such as PLA and PCL. Methodology or Experimental Procedure: The specimens are manufactured using a Sonorus 1G Ultrasound Micro Molding Machine. The used geometry is a rectangular micro-plate of 15x5mm and 1mm of thickness. The materials used for the investigation are PLA and PCL due to biocompatible and degradation properties. The experimentation is divided into two phases. Firstly, the influence of process parameters (vibration amplitude, sonotrodo velocity, ultrasound time and compaction force) on filling behavior is analysed, in Phase 1. Next, when filling cavity is assured, the influence of both cooling time and force compaction on the cavity pressure, part temperature and dimensional accuracy is instigated, which is done in Phase. Results and Discussion: Filling behavior depends on sonotrodo velocity and vibration amplitude. When the ultrasonic time is higher, more ultrasonic energy is applied and the polymer temperature increases. Depending on the cooling time, it is possible that when mold is opened, the micro-plate temperature is too warm. Consequently, the polymer relieve its stored internal energy (ultrasonic and thermal) expanding through the easier direction. This fact is reflected on dimensional accuracy, causing micro-plates thicker than the mold. It has also been observed the most important fact that affects cavity pressure is the compaction configuration during the manufacturing cycle. Conclusions: This research demonstrated the influence of process parameters on the final micro-plated manufactured. Future works will be focused in manufacturing other geometries and analysing the mechanical properties of the specimens.

Keywords: biomaterial, biopolymer, micro injection molding, ultrasound

Procedia PDF Downloads 284