Search results for: relative motion

Authors: Mohammad Moonesun, Ehsan Asadi Asrami, Julia Bodnarchuk

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In the case of Solar Autonomous Underwater Vehicle, which uses photovoltaic panels to provide its required power, due to limitation of energy, accurate estimation of resistance and energy has major sensitivity. In this work, hydrodynamic calculations by numerical method for a solar autonomous underwater vehicle equipped by two 50 W photovoltaic panels has been studied. To evaluate the required power and energy, hull hydrodynamic resistance in several velocities should be taken into account. To do this assessment, the ANSYS FLUENT 18 applied as Computational Fluid Dynamics (CFD) tool that solves Reynolds Average Navier Stokes (RANS) equations around AUV hull, and K-ω SST is used as turbulence model. To validate of solution method and modeling approach, the model of Myring submarine that it’s experimental data was available, is simulated. There is good agreement between numerical and experimental results. Also, these results showed that the K-ω SST Turbulence model is an ideal method to simulate the AUV motion in low velocities.

Keywords: underwater vehicle, hydrodynamic resistance, numerical modelling, CFD, RANS

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Authors: A. A Warra, S. Fatima

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The experimental investigation revealed that the hexane extract of onion seed oil has acid value, iodine value, peroxide value, saponification value, relative density and refractive index of 0.03±0.01 mgKOH/g, 129.80±0.21 gI2/100g, 3.00± 0.00 meq H2O2 203.00±0.71 mgKOH/g, 0.82±0.01and 1.44±0.00 respectively. The percentage yield was 50.28±0.01%. The colour of the oil was light green. We restricted our GC-MS spectra interpretation to compounds identification, particularly fatty acids and they are identified as palmitic acid, linolelaidic acid, oleic acid, stearic acid, behenic acid, linolenic acid and eicosatetraenoic acid. The pH , foam ability (cm³), total fatty matter, total alkali and percentage chloride of the onion oil soap were 11.03± 0.02, 75.13±0.15 (cm³), 36.66 ± 0.02 %, 0.92 ± 0.02% and 0.53 ± 0.15 % respectively. The texture was soft and the colour was lighter green. The results indicated that the hexane extract of the onion seed oil has potential for cosmetic industries.

Keywords: onion seeds, soxhlet extraction, physicochemical, GC-MS, cold saponification

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Authors: David Morton

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This work discusses the relationship between the Vitagraph Company of America (VCA) and the neighborhood of Midwood, Brooklyn, where the company’s largest production studio was located. The relationship between VCA and the Borough of Brooklyn was unique from other production companies in that despite the nationwide popularity of Vitagraph’s films, the content of the films produced by Vitagraph were directly influenced by the cinematic preferences of one specific urban center. In contrast to the national aspirations of the leading production companies of the period such as Twentieth Century Fox, Paramount, and Universal, who set out to attract the broadest audience possible, VCA’s films were aimed to appeal to specific a niche group that embodied Brooklyn’s conservative principles. As a result of the VCA’s alliance with theater owners and movie spectators in Brooklyn, the Vitagraph studio in Midwood became one of the Borough’s most recognizable cultural institutions, and through the production of Vitagraph’s quality films Brooklynites had a significant means of sharing their unique cultural identity with the rest of the United States.

Keywords: Vitagraph Company of America, Midwood, Brooklyn, Vitagrapheville, New York Motion Picture History, silent era, J. Stuart Blackton, Albert Smith

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Authors: Ozden Saygili, Eser Cakti

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Mosques and minarets can be severely damaged as a result of earthquakes. Non-linear behavior of minarets of Mihrimah Sultan and Süleymaniye Mosques and the minaret of St. Sophia are analyzed to investigate seismic response, damage and failure mechanisms of minarets during earthquake. Selected minarets have different height and diameter. Discrete elements method was used to create the numerical minaret models. Analyses were performed using sine waves. Two parameters were used for evaluating the results: the maximum relative dislocation of adjacent drums and the maximum displacement at the top of the minaret. Both parameters were normalized by the drum diameter. The effects of minaret geometry on seismic behavior were evaluated by comparing the results of analyses.

Keywords: discrete element method, earthquake safety, nonlinear analysis, masonry structures

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Authors: Jessyca A. Bessa, Darlan A. Barroso, Jonas P. Reges, Auzuir R. Alexandria

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This work aims to study the rocker. This is a device of the suspension of Formula SAE vehicle that receives efforts from the motion scrolling of the vehicle and transmits them to the chassis frame minimized by a momentum ratio and smoothed by the set spring - damper. A review of parameters used in vehicle dynamics and a geometric analysis of the forces and stresses caused by such was carried out. The main function of the rocker is to reduce the force transmitted to the frame due to movement of rolling and subsequent application of the suspension. This functions is taken as satisfactory, since the force applied to the wheel and which would be transmitted to the chassis is reduced from 3833.9N to 3496.48N. From these values can be further more detailed simulations using the finite element method aimed at mass reduction or even rocker manufacturing feasibility aluminum. Then, the analysis by the finite element method was applied. This analysis uses the theory of discretization of systems and examines the strength of the component based on the distortion energy, determining the maximum straining experienced by the component and the region of higher demand.

Keywords: rocker, suspension, the finite element method, mechatronics engineering

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Authors: M. A. Islam, P. J. Hazell, J. P. Escobedo, M. Saadatfar

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Quasistatic compression and micro structural characterization of closed cell aluminium foams of different pore size and cell distributions has been carried out. Metallic foams have good potential for lightweight structures for impact and blast mitigation and therefore it is important to find out the optimized foam structure (i.e. cell size, shape, relative density, and distribution) to maximize energy absorption. In this paper, we present results for two different aluminium metal foams of density 0.5 g/cc and 0.7 g/cc respectively that have been tested in quasi-static compression. The influence of cell geometry and cell topology on quasistatic compression behavior has been investigated using computed tomography (micro-CT) analysis. The compression behavior and micro structural characterization will be presented.

Keywords: metal foams, micro-CT, cell topology, quasistatic compression

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Authors: R. Ziaie Moayed, M. Alibolandi

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Dynamic behavior of soil are evaluated relative to a number of factors including: strain level, density, number of cycles, material type, fine content, geosynthetic inclusion, saturation, and effective stress. This paper investigate the dynamic behavior of saturated reinforced sand under cyclic stress condition. The cyclic triaxial tests are conducted on remolded specimens under various CSR which reinforced by different arrangement of non-woven geotextile. Aforementioned tests simulate field reinforced saturated deposits during earthquake or other cyclic loadings. This analysis revealed that the geotextile arrangement played dominant role on dynamic soil behavior and as geotextile close to top of specimen, the liquefaction resistance increased.

Keywords: dynamic behavior, reinforced sand, triaxial test, non-woven geotextile

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Authors: Yajing Jiang, Jing Wu, Siyu Bu

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The development of opening residential district is the inevitable trend in China. The landscape resources in opening districts are the main resource for their sharing. However, there is a certain contradiction between the ideal of urban development and the reality of constraints. How to find a balance, to ensure a reasonable open ‘degree’ is particularly important. The opening residential district landscape design should reflect the relative independence of living space, taking into account the basic needs of residents; but also the integration of space, resource sharing, to ensure that the order of daily life on the basis of social interaction and adapt to the dynamic development of the city changes. And ultimately to achieve a reasonable degree of openness to settlements.

Keywords: degree of openness, landscape design, opening residential district, urban design

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Authors: Komlan Sedzro

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We apply the non-parametric, unconditional, hyperbolic order-α quantile estimator to appraise the relative efficiency of Microfinance Institutions in Africa in terms of outreach. Our purpose is to verify if these institutions, which must constantly try to strike a compromise between their social role and financial sustainability are operationally efficient. Using data on African MFIs extracted from the Microfinance Information eXchange (MIX) database and covering the 2004 to 2006 periods, we find that more efficient MFIs are also the most profitable. This result is in line with the view that social performance is not in contradiction with the pursuit of excellent financial performance. Our results also show that large MFIs in terms of asset and those charging the highest fees are not necessarily the most efficient.

Keywords: data envelopment analysis, microfinance institutions, quantile estimation of efficiency, social and financial performance

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Authors: Chek Kim Loi

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The study attempts to undertake an error analysis of prepositions employed in the written work of Form 4 Malay ESL (English as a Second Language) students in Malaysia. The error analysis is undertaken using Richards’s (1974) framework of intralingual and interlingual errors and Bennett’s (1975) framework in identifying prepositional concepts found in the sample. The study first identifies common prepositional errors in the written texts of 150 student participants. It then measures the relative intensities of these errors and finds out the possible causes for the occurrences of these errors. In this study, one significant finding is that among the nine concepts of prepositions examined, the participant students tended to make errors in the use of prepositions of time and place. The present study has pedagogical implications in teaching English prepositions to Malay ESL students.

Keywords: error, interlingual, intralingual, preposition

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Authors: Yagya Sharma, Basanta K. Rana, Arup K. Das

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Rotary entrainment is a phenomenon in which the interfaces of two immiscible fluids are subjected to external flux in the form of rotation. Present work reports the experimental study on rotary motion of a horizontal cylinder between the interface of air and water to observe the penetration of gas inside the liquid. Experiments have been performed to establish entrainment of air mass in water alongside the cylindrical surface. The movement of tracer and seeded particles have been tracked to calculate the speed and path of the entrained air inside water. Simplified particle image velocimetry technique has been used to trace the movement of particles/tracers at the moment they are injected inside the entrainment zone and suspended beads have been used to replicate the particle movement with respect to time in order to determine the flow dynamics of the fluid along the cylinder. Present paper establishes a thorough experimental analysis of the rotary entrainment phenomenon between air and water keeping in interest the extent to which we can intermix the two and also to study its entrainment trajectories.

Keywords: entrainment, gas-liquid flow, particle image velocimetry, stratified layer mixing

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Authors: Lemoussi Somia, Ouali Mohammed, Zemirline Adel

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In precision engineering, including precision positioning, micro-manipulation, robotic systems... a majority of these applications actuated by piezo stack used the compliant amplifier mechanism to amplifying motion and guiding it as needed utilize the flexibility of their components, in this paper, we present a novel approach introducing a symmetric structure comprising three stages, featuring rectangular flexure hinges with a compact size of 77mm×42mm×10mm. This design provides the capability for rotation, translation or a combination of both movements in both directions. The system allows for a displacement of 2107.5 μm when the input displacement of PZT is 50 μm while considering the material constraints of the aluminum alloy (7075 T6) which has a maximum admissible stress of 500 MPa However, our proposed design imposes additional constraints to ensure the stress remains below 361 MPa for optimal performance. These findings were obtained through finite element simulations conducted using ANSYS Workbench. Furthermore, our module facilitates precise control of various components within robotic systems, allowing for adjustable speeds based on specific requirements or desired outcomes.

Keywords: robotic, piezoelectric, compliant mechanism, flexure hinge

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Authors: Norjan Jumaa, David Graham

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We present a Lattice Boltzmann Method (LBM) for multiphase flows with high viscosity and density ratios. The motion of the interface between fluids is modelled by solving the Cahn-Hilliard (CH) equation with LBM. Incompressibility of the velocity fields in each phase is imposed by using a pressure correction scheme. We use a unified LBM approach with separate formulations for the phase field, the pressure less Naiver-Stokes (NS) equations and the pressure Poisson equation required for correction of the velocity field. The implementation has been verified for various test case. Here, we present results for some complex flow problems including two dimensional single and multiple mode Rayleigh-Taylor instability and we obtain good results when comparing with those in the literature. The main focus of our work is related to interactions between aerated or non-aerated waves and structures so we also present results for both high viscosity and low viscosity waves.

Keywords: lattice Boltzmann method, multiphase flows, Rayleigh-Taylor instability, waves

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Authors: Tessa E. Reid, Vanessa N. Kavamura, Maider Abadie, Adriana Torres-Ballesteros, Mark Pawlett, Ian M. Clark, Jim Harris, Tim Mauchline

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The deleterious effect of chemical fertilizer on rhizobacterial diversity has been well documented using 16S rRNA gene amplicon sequencing and predictive metagenomics. Biofertilization is a cost-effective and sustainable alternative; improving strategies depends on isolating beneficial soil microorganisms. Although culturing is widespread in biofertilization, it is unknown whether the composition of cultured isolates closely mirrors native beneficial rhizobacterial populations. This study aimed to determine the relative abundance of culturable plant growth-promoting rhizobacteria (PGPR) isolates within total soil DNA and how potential PGPR populations respond to chemical fertilization in a commercial wheat variety. It was hypothesized that PGPR will be reduced in fertilized relative to unfertilized wheat. Triticum aestivum cv. Cadenza seeds were sown in a nutrient depleted agricultural soil in pots treated with and without nitrogen-phosphorous-potassium (NPK) fertilizer. Rhizosphere and rhizoplane samples were collected at flowering stage (10 weeks) and analyzed by culture-independent (amplicon sequence variance (ASV) analysis of total rhizobacterial DNA) and -dependent (isolation using growth media) techniques. Rhizosphere- and rhizoplane-derived microbiota culture collections were tested for plant growth-promoting traits using functional bioassays. In general, fertilizer addition decreased the proportion of nutrient-solubilizing bacteria (nitrate, phosphate, potassium, iron and, zinc) isolated from rhizocompartments in wheat, whereas salt tolerant bacteria were not affected. A PGPR database was created from isolate 16S rRNA gene sequences and searched against total soil DNA, revealing that 1.52% of total community ASVs were identified as culturable PGPR isolates. Bioassays identified a higher proportion of PGPR in non-fertilized samples (rhizosphere (49%) and rhizoplane (91%)) compared to fertilized samples (rhizosphere (21%) and rhizoplane (19%)) which constituted approximately 1.95% and 1.25% in non-fertilized and fertilized total community DNA, respectively. The analyses of 16S rRNA genes and deduced functional profiles provide an in-depth understanding of the responses of bacterial communities to fertilizer; this study suggests that rhizobacteria, which potentially benefit plants by mobilizing insoluble nutrients in soil, are reduced by chemical fertilizer addition. This knowledge will benefit the development of more targeted biofertilization strategies.

Keywords: bacteria, fertilizer, microbiome, rhizoplane, rhizosphere

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Authors: Amit Gupta, Deepak Juneja, Sorabh Gupta

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This paper presents a model based on distance based approach (DBA) method employed for evaluation, selection, and ranking of replenishment policies for a single location inventory, which hitherto not developed in the literature. This work recognizes the significance of the selection problem, identifies the selection criteria, the relative importance of selection criteria for this research problem. The developed model is capable of comparing any number of alternate inventory policies for various selection criteria where cardinal values are assigned as a rating to alternate inventory polices for selection criteria and weights of selection criteria. The illustrated example demonstrates the model and presents the result in terms of ranking of replenishment policies.

Keywords: DBA, ranking, replenishment policies, selection criteria

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Authors: Ali Maji

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Highway development is an important factor for economic growth and development in both developed and developing countries. In Nigeria about two-third of transportation of goods and persons are done through highway network. It was this that made highway investment to enjoy position of relative high priority on the list of government expenditure programmes in Nigeria today. The paper noted that despite expansion of public investment in highway construction and maintenance of them, road traffic accident is increasing rate. This has acted as a drain of human capital which is a key to economic growth and development in Nigeria. In order to avoid this, the paper recommend introduction of Highway Safety Education (HSE) in Nigerian’s education system and investment in train transportation among other as a sure measure for curtailing highway accident.

Keywords: accident rate, high way development, human capital, national development

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Authors: Giovanni Forte, Melania De Falco, Antonio Santo

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On 24th August 2016, central Italy was affected by a Mw 6.0 earthquake, representing the main shock of a long seismic sequence, which had a second shock Mw 6.6 on 26th October and lasts still nowadays. After the event, several field survey were carried out in the affected areas, which is made of historical masonry buildings. The post event reconnaissance missions were aimed at collecting information on the damage states of the buildings, the triggering of the landslides and the relationships with site effects. In this paper, the data collected after the event are analyzed considering the role of the geological and geomorphological setting and the ground motion scenario. The buildings displayed an uneven damage distribution, which was affected by both topographic and stratigraphic amplification. As pertains the landslides, which were the most recurrent among the ground failures, consisted mainly of rock falls and subordinately of translational slides. Finally, the collected knowledge showed a strong contribution of the local geological and geomorphological site condition on the resulting damage.

Keywords: Amatrice earthquake, damage states, landslides, site effects

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Authors: Mohammed Qasim, Kyoung-Dae Kim

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In this paper, we present the design of the super-ellipsoidal potential function (SEPF), that can be used for autonomous collision avoidance of an unmanned aerial vehicle (UAV) in a 3-dimensional space. In the design of SEPF, we have the full control over the shape and size of the potential function. In particular, we can adjust the length, width, height, and the amount of flattening at the tips of the potential function so that the collision avoidance motion vector generated from the potential function can be adjusted accordingly. Based on the idea of the SEPF, we also propose an approach for the local autonomy of a UAV for its collision avoidance when the UAV is teleoperated by a human operator. In our proposed approach, a teleoperated UAV can not only avoid collision autonomously with other surrounding objects but also track the operator’s control input as closely as possible. As a result, an operator can always be in control of the UAV for his/her high-level guidance and navigation task without worrying too much about the UAVs collision avoidance while it is being teleoperated. The effectiveness of the proposed approach is demonstrated through a human-in-the-loop simulation of quadrotor UAV teleoperation using virtual robot experimentation platform (v-rep) and Matlab programs.

Keywords: artificial potential function, autonomous collision avoidance, teleoperation, quadrotor

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Authors: Hong-Ming Chen

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This work considers the resolution of the Hull and White interest rate model with the jump process. A deterministic process is adopted to model the random behavior of interest rate variation as deterministic perturbations, which is depending on the time t. The Brownian motion and jumps uncertainty are denoted as the integral functions piecewise constant function w(t) and point function θ(t). It shows that the interest rate function and the yield function of the Hull and White interest rate model with jump process can be obtained by solving a nonlinear semi-infinite programming problem. A relaxed cutting plane algorithm is then proposed for solving the resulting optimization problem. The method is calibrated for the U.S. treasury securities at 3-month data and is used to analyze several effects on interest rate prices, including interest rate variability, and the negative correlation between stock returns and interest rates. The numerical results illustrate that our approach essentially generates the yield functions with minimal fitting errors and small oscillation.

Keywords: optimization, interest rate model, jump process, deterministic

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Authors: Sandeep Kumar, Naveen Gupta

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Terahertz (THz) generation has been investigated by beating two cosh-Gaussian laser beams of the same amplitude but different wavenumbers and frequencies through rippled collisionless plasma. The ponderomotive force is operative which is induced due to the intensity gradient of the laser beam over the cross-section area of the wavefront. The electrons evacuate towards a low-intensity regime, which modifies the dielectric function of the medium and results in cross focusing of cosh-Gaussian laser beams. The evolution of spot size of laser beams has been studied by solving nonlinear Schrodinger wave equation (NLSE) with variational technique. The laser beams impart oscillations to electrons which are enhanced with ripple density. The nonlinear oscillatory motion of electrons gives rise to a nonlinear current density driving THz radiation. It has been observed that the periodicity of the ripple density helps to enhance the THz radiation.

Keywords: rippled collisionless plasma, cosh-gaussian laser beam, ponderomotive force, variational technique, nonlinear current density

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Authors: Hassan A. Alshahrani, Mehdi H. Hojjati

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In order to predict and model wrinkling which is caused by out of plane deformation due to compressive loading in the plane of the material during composite prepregs forming, it is necessary to quantitatively understand the relative magnitude of the bending stiffness. This study aims to examine the bending properties of out-of-autoclave (OOA) thermosetting prepreg under vertical cantilever test condition. A direct method for characterizing the bending behavior of composite prepregs was developed. The results from direct measurement were compared with results derived from an image-processing procedure that analyses the captured image during the vertical bending test. A numerical simulation was performed using ABAQUS to confirm the bending stiffness value.

Keywords: Bending stiffness, out-of-autoclave prepreg, forming process, numerical simulation.

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Authors: D. Maneetham, L. Sivhour

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Robotic arm manipulators are widely used to accomplish many kinds of tasks. SCORBOT-ER 4u is a 5-degree of freedom (DOF) vertical articulated educational robotic arm, and all joints are revolute. It is specifically designed to perform pick and place task with its gripper. The pick and place task consists of consideration of the end effector coordinate of the robotic arm and the desired position coordinate in its workspace. This paper describes about forward kinematics modeling and analysis of the robotic end effector motion through joint space. The kinematics problems are defined by the transformation from the Cartesian space to the joint space. Denavit-Hartenberg (D-H) model is used in order to model the robotic links and joints with 4x4 homogeneous matrix. The forward kinematics model is also developed and simulated in MATLAB. The mathematical model is validated by using robotic toolbox in MATLAB. By using this method, it may be applicable to get the end effector coordinate of this robotic arm and other similar types to this arm. The software development of SCORBOT-ER 4u is also described here. PC-and EtherCAT based control technology from BECKHOFF is used to control the arm to express the pick and place task.

Keywords: forward kinematics, D-H model, robotic toolbox, PC- and EtherCAT-based control

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Authors: Junichiro Kawaguchi

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Space debris problems have emerged and threatened the use of low earth orbit around the Earth owing to a large number of spacecraft. In debris removal, a number of research and patents have been proposed and published so far. They assume servicing spacecraft, robots to be built for accessing the target debris objects. The robots should be sophisticated enough automatically to access the debris articulating the attitude and the translation motion with respect to the debris. This paper presents the idea of using the torpedo-like third unsophisticated and disposable body, in addition to the first body of the servicing robot and the second body of the target debris. The third body is launched from the first body from a distance farer than the size of the second body. This paper presents the method and the system, so that the third body is launched from the first body. The third body carries both a net and an inflatable or extendible drag deceleration device and is built small and light. This method enables even a micro to nano satellite to perform contactless and multiple debris removal even via a single flight.

Keywords: ballute, debris removal, echo satellite, gossamer, gun-net, inflatable space structure, small satellite, un-cooperated target

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Authors: M. R. Gad El- Kareem, A. M. K. Abdel Aal, A. Y. Mohamed

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During 2011 and 2012 seasons, Zaghloul date palms received four sprays of silicon (Si) at 0.05 to 0.1% and selenium (Se) at 0.01 to 0.02%. Growths, nutritional status, yield as well as physical and chemical characteristics of the fruits in response to application of silicon and selenium were investigated. Single and combined applications of silicon at 0.05 to 0.1% and selenium at 0.01 to 0.02% was very effective in enhancing the leaf area, total chlorophylls, percentages of N, P, and K in the leaves, yield, bunch weight as well as physical and chemical characteristics of the fruits in relative to the check treatment. Silicon was superior to selenium in this respect. Combined application was favourable than using each alone in this connection. Treating Zaghloul date palms four times with a mixture of silicon at 0.05% + selenium at 0.01% resulted in an economical yield and producing better fruit quality.

Keywords: date palms, Zaghloul, silicon, selenium, leaf area

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Authors: Hussein Altartouri

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The purpose of this paper is to present a modeling and control of the active suspension system using robust state feedback controller implemented for a half car model. This system represents a mechatronic system which contains all the essential components to be considered a complete mechatronic system. This system must adapt different conditions which are difficult to compromise, such as disturbances, slippage, and motion on rough road (that contains rocks, stones, and other miscellanies). Some current automobile suspension systems use passive components only by utilizing spring and damping coefficient with fixed rates. Vehicle suspensions systems are used to provide good road handling and improve passenger comfort. Passive suspensions only offer compromise between these two conflicting criteria. Active suspension poses the ability to reduce the traditional design as a compromise between handling and comfort by directly controlling the suspensions force actuators. In this study, the robust state feedback controller implemented to the active suspensions system for half car model.

Keywords: half-car model, active suspension system, state feedback, road profile

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Authors: Bin Su

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Auckland has a temperate climate with comfortable warm, dry summers and mild, wet winters. An Auckland school normally does not need air conditioning for cooling during the summer and only needs heating during the winter. The Auckland school building thermal design should more focus on winter thermal performance and indoor thermal comfort for energy efficiency. This field study of testing indoor and outdoor air temperatures, relative humidity and indoor surface temperatures of three classrooms with different envelopes were carried out in the Avondale College during the winter months in 2013. According to the field study data, this study is to compare and evaluate winter thermal performance and indoor thermal conditions of school buildings with different envelopes.

Keywords: building envelope, building mass effect, building thermal comfort, building thermal performance, school building

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Authors: Saif Bareq, Vivek Mirgane

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The present paper seeks to explicate the pronunciation of the ‘-s’ and ‘-ed’ suffixes when applied in their relative places in word endings. It attempts to investigate the problems faced by Yemenis in the pronunciation of these suffixes in all occurrences and realizations. It discusses the realization of ‘s’ in the four areas of plural, 3rd person singular and genitive markers, and contraction of ‘has’ and ‘is’ as in he’s, it’s ..,etc. and shows how they are differently represented by three different sounds /s/, /z/ and /z/ based on the phonological structure of the words in which they occur. Similarly, it explains the realization of the ‘-ed’ suffix of the past and past participle marker and how it is realized differently by three sounds governed by the phonological structure of these words. Besides, it tries to shed some light on the English morphophonemic and phonological rules that govern the pronunciation of such troublesome endings. It is hypothesized that the absence of such phenomenon in the mother tongue pronunciation of these suffixes.

Keywords: Suffixes' Pronunciation, Phonological Structure, Phonological Rules, Morpho-Phonemics, Yemeni English

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Authors: Kun Qi, Yuman Zhou, Jianxin He

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A facile fabrication strategy via electrospinning and followed by in situ polymerization to fabricate a highly stretchable and conductive Poly(3,4-ethylenedioxythiophene)/Polyurethane (PEDOT/PU) nanofibrous membrane is reported. PU nanofibers were prepared by electrospinning and then PEDOT was coated on the plasma modified PU nanofiber surface via in-situ polymerization to form flexible PEDOT/PU composite nanofibers with conductivity. The results show PEDOT is successfully synthesized on the surface of PU nanofiber and PEDOT/PU composite nanofibers possess skin-core structure. Furthermore, the experiments indicate the optimal technological parameters of the polymerization process are as follow: The concentration of EDOT monomers is 50 mmol/L, the polymerization time is 24 h and the temperature is 25℃. The PEDOT/PU nanofibers exhibit excellent electrical conductivity ( 27.4 S/cm). In addition, flexible sensor made from conductive PEDOT/PU nanofibers shows highly sensitive response towards tensile strain and also can be used to detect finger motion. The results demonstrate promising application of the as-obtained nanofibrous membrane in flexible wearable electronic fields.

Keywords: electrospinning, polyurethane, PEDOT, conductive nanofiber, flexible senor

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Authors: Mabrak Samir

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The motor performance created by permanent magnetic in a slotless air-gap of a surface mounted permanent-magnet synchronous motor with non magnetic rotor and either sinusoidal or mixed (quasi-Halbatch) magnetization is presented in this paper using polar coordinates. The analysis works for both internal and external rotor motor topologies, The effect of stator slots is introduced by modulating the magnetic field distribution in the slotless stator by the complex relative air-gap permeance, calculated from the conformal transformation of the slot geometry. We compare predicted results of flux density distribution and cogging torque with those obtained by finite-element analysis.

Keywords: air-cored, cogging torque, finite element magnetic field, permanent-magnet

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Authors: Alexander Winkler, Jozef Suchý

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This paper investigates simple implicit force control algorithms realizable with industrial robots. A lot of approaches already published are difficult to implement in commercial robot controllers, because the access to the robot joint torques is necessary or the complete dynamic model of the manipulator is used. In the past we already deal with explicit force control of a position controlled robot. Well known schemes of implicit force control are stiffness control, damping control and impedance control. Using such algorithms the contact force cannot be set directly. It is further the result of controller impedance, environment impedance and the commanded robot motion/position. The relationships of these properties are worked out in this paper in detail for the chosen implicit approaches. They have been adapted to be implementable on a position controlled robot. The behaviors of stiffness control and damping control are verified by practical experiments. For this purpose a suitable test bed was configured. Using the full mechanical impedance within the controller structure will not be practical in the case when the robot is in physical contact with the environment. This fact will be verified by simulation.

Keywords: robot force control, stiffness control, damping control, impedance control, stability

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