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User-Device Interaction Considerations and Testing of A Novel Orthotics for Restoration of Natural Physiological Gait
Get PDFWhen developing orthotics, a major concern is wearability. Wearability is defined as the interaction between the human body and the wearable object. In case of orthotics, the definition extends to include the effects of the human body in motion, or Dynamic Wearability. Major concerns include matching and obtaining close alignment between the structure of the exoskeleton to the wearer, affectation of the biomechanics of locomotion due to added mass and inertia of the device itself as well as the additional kinematic constraints inadvertently imposed on the wearer. Portability and stability are three other major factors that need to be considered. Portable orthotic devices can be used as a part of the wearers everyday life without the need for constant medical supervision that would limit the application of orthotic to clinical settings.In this paper the user-device interaction considerations, manufacturing and testing of a recently designed passively actuated hand free orthotic device is presented. The six-bar device is designed to coordinate the motion of both knee and ankle joints simultaneously that mimics the natural walking gait. Test results from comparing the subject¢‚¬„¢s walking on the ground with and without the orthotic device show only about 3.93% difference in stride length. It is also clear that the toe trajectory is sufficiently close to the experimental trajectory (within ‚±9.6% root-mean-square deviation calculated) to guarantee natural motion of the supported leg
Properties of Polyhydroxy Butyrate Polyvalerate Biopolymeric Nanocomposites Reinforced with Natural Halloysite Nanotubes
Get PDFIn this study, the properties of bacterial fermentation based poly(hydroxybutyrate-co-hydroxyvalerate) –PHBV thermoplastic biopolymer was investigated by reinforcing natural halloysite nanotubes (HNTs). At first, HNTs were added to PHBV polymer by melt processing technique. The modified PHBV resin was then used to fabricate films using compression molding process. X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and tensile tests were performed. XRD results showed mixed intercalated and exfoliated behavior of HNTs in PHBV matrix with an increase in interplanar spacing and decrease in peak intensity. DSC analysis showed that the crystallinity of PHBV resin increased with the increase in HNTs concentration. Also, the DSC endotherm curve showed dual melting peaks indicating formation of different crystalline phases. Higher melting and recrystallization temperature was found in nanophased samples in comparison to the pure PHBV counterpart. The thermal stability, activation energy, tensile and viscoelastic properties of nanophased samples were also increased with an optimum at 3 wt. % HNTs loading. Scanning electron micrographs (SEM) revealed river like pattern in neat films indicating a brittle failure in contrast to rougher surfaces observed in nanophased samples
Spatial Distribution of Material Properties in Load Bearing Femur as Characterized by Evolutionary Structural Optimization
Get PDFThis works aims to simulate bone formation under natural loading using evolutionary structural optimization. Unlike material elimination by hard-kill approach applied previously, the current presentation implements material replacement defined as soft-kill method. A numerical analysis platform was developed and finite element model of sheep femur was constructed using computer tomography data. Quadruple material properties governing soft medullary canal, cancellous as well as plexiform and haversian cortical structures were considered as the main material constituents of the femur. An iterative algorithm was designed for determining the spatial distribution of these tissue types throughout the femur. The model initially started with a homogenous plexiform design and iteratively converged to a final state with heterogeneous density profile, nearly similar to a natural femur. The inefficient regions were gradually changed with mechanically lower grade and lighter tissues and thus the final construct had the least weight but still supported the load. The convergence was achieved successfully. The tissue types were distributed in a mechanically optimum fashion to counteract the applied forces. The resulting internal material assignments provided insights into the structural remodeling of femur within the context of Wolff’s law. Using the developments, bone formation can be simulated numerically under different mechanical loading conditions. Such investigations may provide useful information about the vulnerability of bone as its material properties change with osteoporosis or the fracture risk as a result of malfunction in muscles attached to the femur
Global College Rankings
Get PDFIt is difficult to find consensus regarding the global criteria for college rankings. The worldwide open market for intellectual professionals would be less problematic if there are some standards. There is a question of costs, and which party would be responsible for the expenses. In all the most widely known global rankings, U.S. colleges still generally rule the college rankings. The total research budget in the U.S.A. continues to dominate in the world. Most academic publications on this subject are about the original college ranking used, and many of the newer college ranking systems are not mentioned. The current work serves to fill this gap. The reputation factor is very important in college rankings. As with human reputation (which is the only thing that survives when a human dies) college reputation seems to be one of the few lasting characteristics. If affordability is an important factor, then one of the newer college rankings would be more useful
A Two-Wheeled Mobile Non-Inverted-Pendulum Robot
Get PDFThe two-wheeled mobile non-inverted-pendulum (NIP) robot which is the topic of this paper is a new prototype of a two-wheeled mobile pendulum robot with two internal devices. The pendulum contains the control devices; it is not inverted and free to oscillate. The robot actuation mode is insured by the potential energy of the internal devices. It has two actuators and the free oscillation of the pendulum is mechanically controlled. The robot mechanical structure, the kinematics, the dynamics are given
Positioning the Angle of Attack Sensor on an Unmanned Aerial Vehicle Wing
Get PDFTwo vane type angle of attack sensors, small and large, are tested on the suction surface of a wing of an unmanned aerial vehicle to evaluate the wing interference with angle of attack reading. Tests are performed in the University of Manitoba¢‚¬„¢s wind tunnel with the maximum Reynolds number of 4.5 x 105 to find the optimal location to place sensors on the wing. Each angle of attack sensor is tested at four positions on the wing to investigate the impact of flow deflection caused by the presence of the wing on the sensor readings. Results show that readings are highly sensitive to the normal clearance between the wing and the angle of attack sensor. Accuracy of sensor readings increases by increasing normal clearance. Spanwise placements indicate that the minimum wing interference with angle of attack sensor readings occurs when the sensor is placed beyond the wing tip. To investigate the effect of ailerons on angle of attack sensor readings, sensors are also tested with half, full and with no aileron deflection positions. The effect of aileron deflection is noticeable in large angle of attack sensor readings, while it has a negligible effect on the small sensor readings
All-World Solar Collector Optimum Slope Determination Basing on Site Latitude and Day Number
Get PDFA rule of thumb says that a solar collector should be orientated towards Equator; is it valid all over the world? A rule of thumb says that solar collector should have a latitude tilt value; is it valid all over the world and all over the year? The present work focuses on presenting an algorithm for determining the optimum tilt angle all over the world and for any collector azimuth angle. The Earth surface, located between latitudes 66.45oS and 66.45oN, is divided into 3 characteristic zones. The first zone is the tropical between latitudes 23.45oS and 23.45oN. The second zone is the mid-latitude zone between 23.45oN and 43.45oN and between 23.45oS and 43.45oS. The third zone is the high-latitude zone between 43.45oN and 66.45oN and between 43.45oS and 66.45oS. For each of these zones an adequate method is proposed for calculating the solar collector optimum tilt. Moreover, four simple equations are proposed for predicting daily optimum tilt angle and optimum tilt angle for any number of consecutive days. The yearly possible energy gain in relation that received by a horizontal surface and latitude tilted surface is also calculated on the basis of daily optimum tilts. It is found that the above mentioned rules of thumb are not applicable for a number of consecutive days in the yea
Recycling of Raw Materials, Silicon Wafers and Complete Solar Cells from Photovoltaic Modules
Get PDFPhotovoltaic modules (PVs) are an attractive way of generating electricity in reliable and maintenance-free systems with the use of solar energy. The average lifetime of photovoltaic modules is 25 to 30 years. To offset the negative impact of photovoltaic modules on the environment, it is necessary to introduce a long-term strategy that includes a complete lifecycle of all system components from the production phase through installation and operation to disposal. Recycling of waste products and worn-out systems is an important element of this strategy. Environmental benefits of recycling are related not only to the limited space of landfills, but also to energy saving, raw materials and emission reduction. An important argument for the recycling of photovoltaic modules is the reduction of energy consumption at their production stage through the reuse of existing purified materials. The paper presents selected methods of recycling of used or destroyed PV modules and photovoltaic cells and the results of practical experiments
Reduction of Carbon Dioxide Emissions by Using Photovoltaic Systems in the Syrian Arab Republic
Get PDFSyria is one of the developing countries in which photovoltaic systems were first installed as navigation aids along the Syrian coast. Since then the use of photovoltaic systems is being widely spread in size and type such as stand-alone systems in remote areas and grid-connected systems. This paper presents a survey on photovoltaic systems, their applications in Syria by the end of 2013, and it illustrates that reduction in carbon dioxide emissions can be accomplished by using photovoltaic systems. It shows how many tons of CO2 emissions could be avoided by using photovoltaic systems (stand-alone, gird connected) instead of fossil fuels for either generating electricity or replacing kerosene lamps
Ascending Series Analysis of the Transition Layer
Get PDFThis work considers existing formulation of a recent problem introduced in the literature and involves flow through a transition porous layer, whose solution has been found in terms of Airy’s functions and evaluated using asymptotic series. Ascending series expressions are derived in this work and used in the computations of the solution, namely the computations of Airy’s functions and the recently introduced Nield-Kuznetsov function that arises in the solution to inhomogeneous Airy’s equation. Ascending series expressions developed in this work represent a viable methodology in analyzing flow through the variable permeability transition layer, and are shown to produce results as accurate as the asymptotic series results available in the literature. Both thin and fat transition layers are considered in this work which compares friction factors, velocity profiles, and mean velocities in the two types of layers, Flow through a channel over a Darcy porous layer is also considered in this work and the computed results agree with known results