Search results for: shear force

Authors: Kun Xue, Lvlan Miu, Jiarui Li

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Jetting structures are widely found in particle rings or shells dispersed by the central explosion. In contrast, some explosive dispersal of particles only results in a dispersed cloud without distinctive structures. Employing the coupling method of the compressible computational fluid mechanics and discrete element method (CCFD-DEM), we reveal the underlying physics governing the formation of the jetting structure, which is related to the competition between the shock compaction and gas infiltration, two major processes during the shock interaction with the granular media. If the shock compaction exceeds the gas infiltration, the discernable jetting structures are expected, precipitated by the agglomerates of fast-moving particles induced by the heterogenous network of force chains. Otherwise, particles are uniformly accelerated by the interstitial flows, and no distinguishable jetting structures are formed. We proceed to devise the phase map of the jetting formation in the space defined by two dimensionless parameters which characterize the timescales of the shock compaction and the gas infiltration, respectively.

Keywords: compressible multiphase flows, DEM, granular jetting, pattern formation

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Authors: Aritras Roy, Rinku Mukherjee

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The current study couples a quasi-steady Vortex Lattice Method and a camber correcting technique, ‘Decambering’ for unsteady post-stall flow prediction. The wake is force-free and discrete such that the wake lattices move with the free-stream once shed from the wing. It is observed that the time-averaged unsteady coefficient of lift sees a relative drop at post-stall angles of attack in comparison to its steady counterpart for some angles of attack. Multiple solutions occur at post-stall and three different algorithms to choose solutions in these regimes show both unsteadiness and non-convergence of the iterations. The distribution of coefficient of lift on the wing span also shows sawtooth. Distribution of vorticity changes both along span and in the direction of the free-stream as the wake develops over time with distinct roll-up, which increases with time.

Keywords: post-stall, unsteady, wing, aerodynamics

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Authors: Mohammad Sadeghian, Mohsen Sadeghian

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In this paper, planning catamaran and mono-hull vessels resistance and trim in calm waters were considered. Hydrodynamic analysis of fast mono-hull planning vessel was also investigated. For hull form geometry optimization, numerical methods of different parameters were used for this type of vessels. Hull material was selected as carbon fiber composite. Exact architectural aspects were specified and stability calculations were performed, as well. Hydrodynamic calculations to extract the resistance force using semi-analytical methods and numerical modeling were carried out. Free surface numerical analysis of vessel in designed draft using finite volume method and double phase were evaluated and verified by experimental tests.

Keywords: fast vessel, hydrostatic and hydrodynamic optimization, free surface flow, computational fluid dynamics

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Authors: P. M. Keshtiban, M. Zdshakoyan, G. Faragi

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Different severe plastic deformation (SPD) methods are the most successful ways to build nano-structural materials from coarse grain samples without changing the cross-sectional area. One of the most widely used methods in the SPD process is equal channel angler pressing (ECAP). In this paper, ECAP process on Al1050 sheets was evaluated at room temperature by both experiments and finite element method. Since, one of the main objectives of SPD processes is to achieve high equivalent plastic strain (PEEQ) in one cycle, the values of PEEQ obtained by finite element simulation. Also, force-displacement curve achieved by FEM. To study the changes of mechanical properties, micro-hardness tests were conducted on samples and improvement in the mechanical properties were investigated. Results show that there is the good proportion between FEM, theory and experimental results.

Keywords: AL1050, experiments, finite element method, severe plastic deformation

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Authors: A. Armin, R. Fotouhi, W. Szyszkowski

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In this paper a 3-D finite element (FE) investigation of soil-blade interaction is described. The effects of blade’s shape and rake angle are examined both numerically and experimentally. The soil is considered as an elastic-plastic granular material with non-associated Drucker-Prager material model. Contact elements with different properties are used to mimic soil-blade sliding and soil-soil cutting phenomena. A separation criterion is presented and a procedure to evaluate the forces acting on the blade is given and discussed in detail. Experimental results were derived from tests using soil bin facility and instruments at the University of Saskatchewan. During motion of the blade, load cells collect data and send them to a computer. The measured forces using load cells had noisy signals which are needed to be filtered. The FE results are compared with experimental results for verification. This technique can be used in blade shape optimization and design of more complicated blade’s shape.

Keywords: finite element analysis, experimental results, blade force, soil-blade contact modeling

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Authors: Maciej Major, Izabela Major

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The aim of this paper is a numerical analysis of three-layered block design to walls construction subjected to the dynamic load. The block consists of the layers: concrete with rubber pads in shape of crosses, space filled with air and concrete with I-shape rubber pads. The main purpose of rubber inserts embedded during the production process is additional protection against the transversal dynamic load. For the analysis, as rubber, the Zahorski hyperelastic incompressible material model was assumed. A concentrated force as dynamic load applied to the external block surface was investigated. The results for the considered block observed as the stress distribution plot were compared to the results obtained for the solid concrete block. In order to estimate the percentage damping of proposed composite, rubber-concrete block in relation to the solid block the numerical analysis with the use of finite element method based on ADINA software was performed.

Keywords: dynamics, composite, rubber, Zahorski

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Authors: Salma Akter, Md. Kamal Uddin

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This study aims to demonstrate how top-down shelter policy and its resultant dwelling environment leads to ‘everyday compromise’ by the grassroots according to subjective (satisfaction) and objective (physical design elements and physical environmental elements) indicators, which are measured across three levels of the settlement; macro (Community), meso (Neighborhood or shelter/built environment) and micro (family). Ashrayan Prakalpa is a resettlement /housing project of Government of Bangladesh for providing shelters and human resources development activities like education, microcredit, and training programme to landless, homeless and rootless people. Despite the integrated nature of the shelter policies (comprises poverty alleviation, employment opportunity, secured tenure, and livelihood training), the ‘quality of life’ issue at the different levels of settlements becomes questionable. As dwellers of shelter units (although formally termed as ‘barracks’ rather shelter or housing) remain on the receiving end of government’s resettlement policies, they often involve with spatial-physical and socio-economic negotiation and assume curious forms of spatial practice, which often upholds contradiction with policy planning. Thus, policy based shelter force dwellers to persistently compromise with their provided built environments both in overtly and covertly. Compromising with prescribed designed space and facilities across living places articulated their negotiation with the quality of allocated space, built form and infrastructures, which in turn exert as less quality of life. The top-down shelter project, Dakshin Chandani Mahal Ashrayan Prakalpa at Dighalia Upazila, the study area located at the Eastern fringe area of Khulna, Bangladesh, is still in progress to resettle internally displaced and homeless people. In terms of methodology, this research is primarily exploratory and adopts a case study method, and an analytical framework is developed through the deductive approach for evaluating the quality of life. Secondary data have been obtained from housing policy analysis and relevant literature review, while key informant interview, focus group discussion, necessary drawings and photographs and participant observation across dwelling, neighborhood, and community level have also been administered as primary data collection methodology. Findings have revealed that various shortages, inadequacies, and negligence of policymakers force to compromise with allocated designed space, physical infrastructure and economic opportunities across dwelling, neighborhood and mostly community level. Thus, the outcome of this study can be beneficial for a global-level understating of the compromising the ‘quality of life’ under top-down shelter policy. Locally, for instance, in the context of Bangladesh, it can help policymakers and concerned authorities to formulate the shelter policies and take initiatives to improve the well-being of marginalized.

Keywords: Ashrayan Prakalpa, compromise, displaced people, quality of life

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Authors: Mehdi Habibnia Rami, Shidvash Vakilipour, Mohammad H. Sabour, Rouzbeh Riazi, Hossein Hassannia

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This paper deals with the steady and unsteady flow behavior on the separation bubble occurring on the rear portion of the suction side of T106A blade. The first phase was to implement the steady condition capturing the separation bubble. To accurately predict the separated region, the effects of three different turbulence models and computational grids were separately investigated. The results of Large Eddy Simulation (LES) model on the finest grid structure are acceptably in a good agreement with its relevant experimental results. The second phase is mainly to address the effects of wake entrance on bubble disappearance in unsteady situation. In the current simulations, from what was suggested in an experiment, simulating the flow unsteadiness, with concentrations on small scale disturbances instead of simulating a complete oncoming wake, is the key issue. Subsequently, the results from the current strategy to apply the effects of the wake and two other experimental work were compared to be in a good agreement. Between the two experiments, one of them deals with wake passing unsteady flow, and the other one implements experimentally the same approach as the current Computational Fluid Dynamics (CFD) simulation.

Keywords: low-pressure turbine cascade, large-Eddy simulation (LES), RANS turbulence models, unsteady flow measurements, flow separation

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Authors: Mehran Naghizaderokni, Asscar Janalizadechobbasty

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This paper explores probabilistic method for assessing the liquefaction potential of sandy soils. The current simplified methods for assessing soil liquefaction potential use a deterministic safety factor in order to determine whether liquefaction will occur or not. However, these methods are unable to determine the liquefaction probability related to a safety factor. A solution to this problem can be found by reliability analysis.This paper presents a reliability analysis method based on the popular certain liquefaction analysis method. The proposed probabilistic method is formulated based on the results of reliability analyses of 190 field records and observations of soil performance against liquefaction. The results of the present study show that confidence coefficient greater and smaller than 1 does not mean safety and/or liquefaction in cadence for liquefaction, and for assuring liquefaction probability, reliability based method analysis should be used. This reliability method uses the empirical acceleration attenuation law in the Chalos area to derive the probability density distribution function and the statistics for the earthquake-induced cyclic shear stress ratio (CSR). The CSR and CRR statistics are used in continuity with the first order and second moment method to calculate the relation between the liquefaction probability, the safety factor and the reliability index. Based on the proposed method, the liquefaction probability related to a safety factor can be easily calculated. The influence of some of the soil parameters on the liquefaction probability can be quantitatively evaluated.

Keywords: liquefaction, reliability analysis, chalos area, civil and structural engineering

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Authors: Chonmapat Torasa

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This paper presents the performance of electricity generation and consumption from solar generator installed at Rajabhat Suan Sunandha’s learning center in Samutsongkram. The result from the experiment showed that solar cell began to work and distribute the current into the system when the solar energy intensity was 340 w/m2, starting from 8:00 am to 4:00 pm (duration of 8 hours). The highest intensity read during the experiment was 1,051.64w/m2. The solar power was 38.74kWh/day. The electromotive force from solar cell averagely was 93.6V. However, when connecting solar cell with the battery charge controller system, the voltage was dropped to 69.07V. After evaluating the power distribution ability and electricity load of tested solar cell, the result showed that it could generate power to 11 units of 36-wattfluorescent lamp bulbs, which was altogether 396W. In the meantime, the AC to DC power converter generated 3.55A to the load, and gave 781VA.

Keywords: solar cell, solar-cell power generating system, computer, systems engineering

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Authors: Reza Dinarvand, Mahdi Sadeghian, Somaye Sadeghian

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Prediction of the ultimate bearing capacity of piles (Qu) is one of the basic issues in geotechnical engineering. So far, several methods have been used to estimate Qu, including the recently developed artificial intelligence methods. In recent years, optimization algorithms have been used to minimize artificial network errors, such as colony algorithms, genetic algorithms, imperialist competitive algorithms, and so on. In the present research, artificial neural networks based on colonial competition algorithm (ANN-ICA) were used, and their results were compared with other methods. The results of laboratory tests of short piles in clayey soils with parameters such as pile diameter, pile buried length, eccentricity of load and undrained shear resistance of soil were used for modeling and evaluation. The results showed that ICA-based artificial neural networks predicted lateral bearing capacity of short piles with a correlation coefficient of 0.9865 for training data and 0.975 for test data. Furthermore, the results of the model indicated the superiority of ICA-based artificial neural networks compared to back-propagation artificial neural networks as well as the Broms and Hansen methods.

Keywords: artificial neural network, clayey soil, imperialist competition algorithm, lateral bearing capacity, short pile

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Authors: Resul Fikir

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Unmanned Aircraft Systems (UAS) become indispensable parts of modern air power as force multiplier. One of the main advantages of UAS is long endurance. UAS have to take extra payloads to accomplish different missions but these payloads decrease endurance of aircraft because of increasing drag. There are continuing researches to increase the capability of UAS. There are some vertical thermal air currents, which can cause climb and increase endurance, in nature. Birds and gliders use thermals to gain altitude with no effort. UAS have wide wing which can use of thermals like birds and gliders. Thermal regions, which is area of 2000-3000 meter (1 NM), exist all around the world. It is free and clean source. This study analyses if thermal regions can be adopted and implemented as an assistant tool for UAS route planning. First and second part of study will contain information about the thermal regions and current applications about UAS in aviation and climbing performance with a real example. Continuing parts will analyze the contribution of thermal regions to UAS endurance. Contribution is important because planning declaration of UAS navigation rules will be in 2015.

Keywords: airways, thermals, UAS, UAS roadmap

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Authors: Ibrahim Abdel Gadir Malik, Dafalla Siddig Dafalla, Abdelazim Ibrahim

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Jabal Omar is located in the western side of Makkah city in Saudi Arabia. The proposed Jabal Omar Development project includes several multi-storey buildings, roads, bridges and below ground structures founded at various depths. In this study, geological mapping and site inspection which covered pre-selected areas were carried out within the easily accessed parts. Geological features; including rock types, structures, degree of weathering, and geotechnical hazards were observed and analyzed with specified software and also were documented in form of photographs. The presence of joints and fractures in the area made the rock blocks small and weak. The site is full of jointing; it was observed that, the northern side consists of 3 to 4 jointing systems with 2 random fractures associated with dykes. The southern part is affected by 2 to 3 jointing systems with minor fault and shear zones. From the field measurements and observations, it was concluded that, the Jabal Omar intruded by andesitic and basaltic dykes of different thickness and orientation. These dykes made the outcrop weak, highly deformed and made the rock masses sensitive to weathering.

Keywords: rock, slope, stabilization, protection, Makkah

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Authors: Abdelghani May

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This paper reports on experimental investigations concerning the underlying reasons for the anisotropic behavior observed during the cyclic loading of AA2017 aluminum alloy. Initially, we quantified the evolution of fatigue damage resulting from controlled proportional cyclic loadings along the axial and shear directions. Our primary objective at this stage was to verify the anisotropic mechanical behavior recently observed. To accomplish this, we utilized various models of fatigue damage quantification and conducted a comparative study of the obtained results. Our analysis confirmed the anisotropic nature of the material under investigation. In the subsequent step, we performed microstructural investigations aimed at understanding the origins of the anisotropic mechanical behavior. To this end, we utilized scanning electron microscopy to examine the phases and precipitates in both the transversal and longitudinal sections. Our findings indicate that the structure and morphology of these entities are responsible for the anisotropic behavior observed in the aluminum alloy. Furthermore, results obtained from Kikuchi diagrams, pole figures, and inverse pole figures have corroborated these conclusions. These findings demonstrate significant differences in the crystallographic texture of the material.

Keywords: microstructural investigation, fatigue damage quantification, anisotropic behavior, AA2017 aluminum alloy, cyclic loading, crystallographic texture, scanning electron microscopy

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Authors: Roy Alex, Dr. Shampa I Dev

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Abstract Nine out of twenty-eight states in India have enacted anti-conversion laws to regulate religious conversions by use of force, allurement, inducement, or fraudulent means. The vagueness of the definitions of the terms used in these laws makes them inconsistent with the provisions of the right to freedom of religion guaranteed by the Constitution. It is a critical question whether these laws protect the religious freedom of groups that are “vulnerable” to missionary inducements, or are they restricting the freedom of citizens to propagate their religion to others or change their religious identity? This article looks into the constitutionality of the anti-conversion laws passed in the Indian States and argues that these laws limit the freedom of religion guaranteed under Article 25 of the Constitution of India. The ambiguity in the anti-conversion laws passed in various states of India is brought out by critically analyzing multiple cases charged under anti-conversion laws.

Keywords: Freedom of Religion, Anti-conversion Laws, allurement, inducement, and fraudulent means.

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Authors: Giulio Rosati, Luciano Sappia, Rossana Madrid, Noemi Rozlòsnik

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The addition of PEG of different molecular weights has important effects on the physical, electrical and electrochemical properties of iron(III)-tosylate doped PEDOT. This particular polymer can be easily spin coated over plastic discs, optimizing thickness and uniformity of the PEDOT-PEG films. The conductivity and morphological analysis of the hybrid PEDOT-PEG polymer by 4-point probe (4PP), 12-point probe (12PP), and conductive AFM (C-AFM) show strong effects of the PEG doping. Moreover, the conductive films kinetics at the nanoscale, in response to different bias voltages, change radically depending on the PEG molecular weight. The hybrid conductive films show also interesting electrochemical properties, making the PEDOT PEG doping appealing for biosensing applications both for EIS-based and amperometric affinity/catalytic biosensors.

Keywords: atomic force microscopy, biosensors, four-point probe, nano-films, PEDOT

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Authors: Khalid M. Kheiralla, Georgios Boutsis, Mohammed Y. Abdelgalil, Mohammed A. Ali, Nuha E. Mohamed

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The present study focus on integrated geoelectrical surveys carried out in the mineralization zone in Erkowit region, Eastern Sudan to determine the extensions of the potential ore deposits on the topographically high hilly area and under the cover of alluvium along the nearby wadi and to locate other occurrences if any. The magnetic method (MAG) and the electrical resistivity tomography (ERT) were employed for the survey. Eleven traverses were aligned approximately at right angles to the general strike of the rock formations. The disseminated sulfides are located on the alteration shear zone which is composed of granitic and dioritic highly ferruginated rock occupying the southwestern and central parts of the area, this was confirmed using thin and polished sections mineralogical analysis. The magnetic data indicates low magnetic values for wadi sedimentary deposits in its southern part of the area, and high anomalies which are suspected as gossans due to magnetite formed during wall rock alteration consequent to mineralization. The significant ERT images define low resistivity zone as traced as sheared zones which may associated with the main loci of ore deposition. By itself, no geophysical anomaly can simply be correlated with lithology, instead, magnetic and ERT anomalies raised due to variations in some specific physical properties of rocks which were extremely useful in mineral exploration.

Keywords: ERT, magnetic, mineralization, Red Sea, Sudan

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Authors: Mohammad Ali Badri, Pouya Molana, Amin Rezvanpour

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In this paper, planning catamaran and mono-hull vessels resistance and trim in calm waters were considered. Hydrodynamic analysis of fast mono-hull planning vessel was also investigated. In order to hull form geometry optimization, numerical methods of different parameters were used for this type of vessels. Hull material was selected in carbon fiber composite. Exact architectural aspects were specified and stability calculations were performed as well. Hydrodynamic calculations to extract the resistance force using semi-analytical methods and numerical modeling were carried out. Free surface numerical analysis of vessel in designed draft using finite volume method and double phase were evaluated and verified by experimental tests.

Keywords: fast vessel, hydrostatic and hydrodynamic optimization, free surface flow, computational fluid dynamics

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Authors: Leandro Moura da Silva

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The international community has strived to create legal mechanisms to protect their biodiversity, but this can represent, sometimes, particularly in the case of regulatory regime on access to genetic resources, an excessive nationalism which transforms itself into a significant obstacle to scientific progress causing damages to the country and to local farmers. Although it has been poorly publicized in the media, the international legal system was marked, in 2014, by the entry into force of the Nagoya Protocol, which regulates the access and benefit sharing of genetic resources of the States Party to that legal instrument. However, it’s not reasonable to think of regulating access to genetic resources without reflecting on the links of this important subject with other related issues, such as family farming and agribusiness, food safety, food security, intellectual property rights (on seeds, genetic material, new plant varieties, etc.), environmental sustainability, biodiversity, and biosafety.

Keywords: international law, regulation on agriculture, agronomy techniques, sustainability, genetic resources and new crop varieties, CBD, Nagoya Protocol, ITPGRFA

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Authors: Nor Jannah Mohd Sebri, Khairul Anuar Mat Amin

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Dication cross-linked gellan gum hydrogel loaded with Ibuprofen with excellent mechanical properties had been synthesized as potential candidate for non-toxic biocompatible polymer material in tissue engineering. The gellan gum hydrogel with 5% Ibuprofen had produced a slow release profile with total drug release time of 25 hours as a resulting low swelling value recorded at 22+0.5%. Its compressive strength, 200.13+21 kPa was highest of all other hydrogel ratio of 0.5% and 1.0% Ibuprofen incorporation. Young’s Modulus of the hydrogel with 5% Ibuprofen was recorded at 1.8+0.01 MPa, indicating good gel strength in which it is capable of withstanding a fair amount of subjected force during topical wound dressing application. Excellent mechanical properties, together with slow release profile, make the ibuprofen-loaded hydrogel a prospect candidate as biocompatible extracellular matrices in wound management.

Keywords: gellan gum, ibuprofen, slow drug release, hydrogel

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Authors: Reza Safari, Ali Rajabzadeh Ghatari, Raheleh Hossseinzadeh Mahabadi

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In the present world, there are different pressures on firms such as competition, legislations, social etc. these pressures force the firms to follow “survival” as their primary goal and then growth. One of the main factors that helps firms to reach their goals is proper financial performance. To find out about the financial performance, a firm should monitors its financial performance. Financial performance affected by many factors. This research seeks to clear which financial performance indicators are most important according to Environmental situation of a firm and what are their priorities. To do so, environmental indicators specified as presented on OECD Key Environmental Indicators 2008 and so the financial performance indicators such as Profitability, Liquidity, Gearing, Investor ratios, and etc. At this stage, the affections questioned through questionnaires. After gaining the results, data analyzed using Promethee technique. By using decision matrixes extracted from those techniques an expert system designed. This expert system suggests the suitable financial performance indicators and their ranking by receiving the environment situation given environment indicators weight.

Keywords: environment indicators, financial performance indicators, promethee, expert system

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Authors: Aneesa Shafi

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Reproduction is a complex term in a setting where it is continuously being shaped by epistemological shifts in knowledge. It denotes not just fertility, birth and childcare related practices but also the ideas that shape those practices. These ideas and practices figure into understandings of social and cultural renewal. Patriarchy continues to be a dominating force in the formation of these ideas and practices. Contemporary times are characterized by the resurgence of the whims of patriarchal politics in delineating the margins of women’s health care. This has further emboldened the struggle for reproductive rights on the global stage. The paper examines the subordination of the right to bodily autonomy of women within the ambit of their reproductive rights. Reproductive rights are recognized human rights and women’s rights. Why these rights of women face stiff opposition is established, as is the structure that creates hurdles to their enjoyment. The negotiation of this structure in the everyday life through women’s agency is also established. The reproductive sphere includes not just the process of reproduction but also social reproduction- domestic work, spheres of production and reproduction, population and birth (control) issues.

Keywords: patriarchy, women, reproduction, gender

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Authors: Drew Commandeur, Ryan Brodie, Sandra Hundza, Marc Klimstra

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The amplitude of raw electromyography (EMG) is affected by recording conditions and often requires normalization to make meaningful comparisons. Bioelectric methods normalize with an EMG signal recorded during a standardized task or from the experimental protocol itself, while biomechanical methods often involve measurements with an additional sensor such as a force transducer. Common bioelectric normalization techniques for treadmill walking include maximum voluntary isometric contraction (MVIC), dynamic EMG peak (EMGPeak) or dynamic EMG mean (EMGMean). There are several concerns with using MVICs to normalize EMG, including poor reliability and potential discomfort. A limitation of bioelectric normalization techniques is that they could result in a misrepresentation of the absolute magnitude of force generated by the muscle and impact the interpretation of EMG between functionally disparate groups. Additionally, methods that normalize to EMG recorded during the task may eliminate some real inter-individual variability due to biological variation. This study compared biomechanical and bioelectric EMG normalization techniques during treadmill walking to assess the impact of the normalization method on the functional interpretation of EMG data. For the biomechanical method, we normalized EMG to a target torque (EMGTS) and the bioelectric methods used were normalization to the mean and peak of the signal during the walking task (EMGMean and EMGPeak). The effect of normalization on muscle activation pattern, EMG amplitude, and inter-individual variability were compared between disparate cohorts of OLD (76.6 yrs N=11) and YOUNG (26.6 yrs N=11) adults. Participants walked on a treadmill at a self-selected pace while EMG was recorded from the right lower limb. EMG data from the soleus (SOL), medial gastrocnemius (MG), tibialis anterior (TA), vastus lateralis (VL), and biceps femoris (BF) were phase averaged into 16 bins (phases) representing the gait cycle with bins 1-10 associated with right stance and bins 11-16 with right swing. Pearson’s correlations showed that activation patterns across the gait cycle were similar between all methods, ranging from r =0.86 to r=1.00 with p<0.05. This indicates that each method can characterize the muscle activation pattern during walking. Repeated measures ANOVA showed a main effect for age in MG for EMGPeak but no other main effects were observed. Interactions between age*phase of EMG amplitude between YOUNG and OLD with each method resulted in different statistical interpretation between methods. EMGTS normalization characterized the fewest differences (four phases across all 5 muscles) while EMGMean (11 phases) and EMGPeak (19 phases) showed considerably more differences between cohorts. The second notable finding was that coefficient of variation, the representation of inter-individual variability, was greatest for EMGTS and lowest for EMGMean while EMGPeak was slightly higher than EMGMean for all muscles. This finding supports our expectation that EMGTS normalization would retain inter-individual variability which may be desirable, however, it also suggests that even when large differences are expected, a larger sample size may be required to observe the differences. Our findings clearly indicate that interpretation of EMG is highly dependent on the normalization method used, and it is essential to consider the strengths and limitations of each method when drawing conclusions.

Keywords: electromyography, EMG normalization, functional EMG, older adults

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Authors: S. M. AL-Shomar, N. B. Ibrahim, Sahrim Hj. Ahmad

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ZnO thin films with various Gd doping concentration (0, 0.01, 0.03 and 0.05 mol/L) have been synthesized by sol–gel method on quartz substrates at annealing temperature of 600 ºC. X-ray analysis reveals that ZnO(Gd) films have hexagonal wurtzite structure. No peaks that correspond to Gd metal clusters or gadolinium acetylacetonate are detected in the patterns. The position of the main peak (101) shifts to higher angles after doping. The surface morphologies studied using a field emission scanning electron microscope (FESEM) showed that the grain size and the films thickness reduced gradually with the increment of Gd concentration. The roughness of ZnO film investigated by an atomic force microscopy (AFM) showed that the films are smooth and high dense grain. The roughness of doped films decreased from 6.05 to 4.84 rms with the increment of dopant concentration.The optical measurements using a UV-Vis-NIR spectroscopy showed that the Gd doped ZnO thin films have high transmittance (above 80%) in the visible range and the optical band gap increase with doping concentration from 3.13 to 3.39 eV. The doped films show low electrical resistivity 2.6 × 10-3Ω.cm.at high doping concentration.

Keywords: Gd doped ZnO, electric, optics, microstructure

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Authors: M. Arunachalam, M. Pandey

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Nacre, a biological material that forms the inner-layer of sea shells can achieve high toughness and strength by way of staggered arrangement of strong tablets with soft and weak organic interface. Under applied loads the tablets slide over the adjacent tablets, thus generating inelastic deformation and toughness on macroscopic scale. A two dimensional finite element based homogenization methodology is adopted for obtaining the effective material properties of Nacre using a representative volume element (RVE) at finite deformations. In this work, the material behaviour for tablet and interface are assumed to be Isotropic elastic and Isotropic elastic-perfectly plastic with strain softening respectively. Numerical experiments such as uniaxial tension test along X, Y directions and simple shear test are performed on the RVE with uniform displacement and periodic constraints applied at the RVE boundaries to obtain the anisotropic homogenized response and maximum local stresses within each constituents of Nacre. Homogenized material model is then tested for macroscopic structure under three point bending condition and the results obtained are comparable with the results obtained for detailed microstructure based structure, thus homogenization provides a bridge between macroscopic scale and microscopic scale and homogenized material properties obtained from microstructural (RVE) analysis could be used in large scale structural analysis.

Keywords: finite element, homogenization, inelastic deformation, staggered arrangement

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Authors: Arkadiusz Mezyk, Wojciech Klein, Mariusz Pawlak, Jacek Gnilka

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The aortic heart valve stents should fulfill many criterions. These criteria have a strong impact on the geometrical shape of the stent. Usually, the final construction of stent is a result of many year experience and knowledge. Depending on patents claims, different stent shapes are produced by different companies. This causes difficulties for biomechanics engineers narrowing the domain of feasible solutions. The paper present optimization method for stent geometry defining by a specific analytical equation based on various mathematical functions. This formula was implemented as APDL script language in ANSYS finite element environment. For the purpose of simulation tests, a few parameters were separated from developed equation. The application of the genetic algorithms allows finding the best solution due to selected objective function. Obtained solution takes into account parameters such as radial force, compression ratio and coefficient of expansion on the transverse axial.

Keywords: aortic stent, optimization process, geometry, finite element method

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Authors: Lamia L. G. Al-Mahamad, Benjamin R. Horrocks, Andrew Houlton

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Hydrogels based on metal coordination polymers of nucleosides and a range of metal ions (Au, Ag, Cu) have been prepared and characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ultraviolet-visible absorption spectroscopy, and powder X-ray diffraction. AFM images of the xerogels revealed the formation of extremely long polymer molecules (> 10 micrometers, the maximum scan range). This result is also consistent with TEM images which show a fibrous morphology. Oxidative doping of the Au-nucleoside fibres produces an electrically conductive nanowire. No sharp Bragg peaks were found at the at the X-ray diffraction pattern for metal ions hydrogels indicating that the samples were amorphous, but instead the data showed broad peaks in the range 20 < Q < 40 and correspond to distances d=2μ/Q. The data was analysed using a simplified Rietveld method by fitting a regression model to obtain the distance between atoms.

Keywords: hydrogel, metal ions, nanowire, nucleoside

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Authors: Pankaj Chandna, Dinesh Kumar

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The present work analyses different parameters of end milling to minimize the surface roughness for AISI D2 steel. D2 Steel is generally used for stamping or forming dies, punches, forming rolls, knives, slitters, shear blades, tools, scrap choppers, tyre shredders etc. Surface roughness is one of the main indices that determines the quality of machined products and is influenced by various cutting parameters. In machining operations, achieving desired surface quality by optimization of machining parameters, is a challenging job. In case of mating components the surface roughness become more essential and is influenced by the cutting parameters, because, these quality structures are highly correlated and are expected to be influenced directly or indirectly by the direct effect of process parameters or their interactive effects (i.e. on process environment). In this work, the effects of selected process parameters on surface roughness and subsequent setting of parameters with the levels have been accomplished by Taguchi’s parameter design approach. The experiments have been performed as per the combination of levels of different process parameters suggested by L9 orthogonal array. Experimental investigation of the end milling of AISI D2 steel with carbide tool by varying feed, speed and depth of cut and the surface roughness has been measured using surface roughness tester. Analyses of variance have been performed for mean and signal-to-noise ratio to estimate the contribution of the different process parameters on the process.

Keywords: D2 steel, orthogonal array, optimization, surface roughness, Taguchi methodology

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Authors: Resul Fikir

Abstract:

Unmanned Aircraft Systems (UAS) become indispensable parts of modern airpower as force multiplier .One of the main advantages of UAS is long endurance. UAS have to take extra payloads to accomplish different missions but these payloads decrease endurance of aircraft because of increasing drug. There are continuing researches to increase the capability of UAS. There are some vertical thermal air currents, which can cause climb and increase endurance, in nature. Birds and gliders use thermals to gain altitude with no effort. UAS have wide wing which can use of thermals like birds and gliders. Thermal regions, which is area of 2-3 NM, exist all around the world. It is free and clean source. This study analyses if thermal regions can be adopted and implemented as an assistant tool for UAS route planning. First and second part of study will contain information about the thermal regions and current applications about UAS in aviation and climbing performance with a real example. Continuing parts will analyze the contribution of thermal regions to UAS endurance. Contribution is important because planning declaration of UAS navigation rules will be in 2015.

Keywords: unmanned aircraft systems, Air4All, thermals, gliders

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Authors: Tarek S. Duzan, Abdulaziz F. Ettir

Abstract:

Wave velocities, Core and Log petrophysical data were collected from recently drilled four new wells scattered through-out the Dahra/Jofra (PL-5) Reservoir. The collected data were analyzed for the relationships of Wave Velocities with rock property such as Porosity, permeability and Bulk Density. Lots of Literature review reveals a number of differing results and conclusions regarding wave velocities (Compressional Waves (Vp) and Shear Waves (Vs)) versus rock petrophysical property relationships, especially in carbonate reservoirs. In this paper, we focused on the relationships between wave velocities (Vp , Vs) and the ratio Vp/Vs with rock properties for shallow marine libyan carbonate reservoir (Real Case). Upon data analysis, a relationship between petrophysical properties and wave velocities (Vp, Vs) and the ratio Vp/Vs has been found. Porosity and bulk density properties have shown exponential relationship with wave velocities, while permeability has shown a power relationship in the interested zone. It is also clear that wave velocities (Vp , Vs) seems to be a good indicator for the lithology change with true vertical depth. Therefore, it is highly recommended to use the output relationships to predict porosity, bulk density and permeability of the similar reservoir type utilizing the most recent seismic data.

Keywords: conventional core analysis (porosity, permeability bulk density) data, VS wave and P-wave velocities, shallow carbonate reservoir in D/J field

Procedia PDF Downloads 326