Abstract: During manned exploration of space, missions will require astronaut crewmembers to perform Extra Vehicular Activities (EVAs) for a variety of tasks. These EVAs take place after long periods of operations in space, and in and around unique vehicles, space structures and systems. Considering the remoteness and time spans in which these vehicles will operate, EVA system operations should utilize common worksites, tools and procedures as much as possible to increase the efficiency of training and proficiency in operations. All of the preparations need to be carried out based on studies of astronaut motions. Until now, development and training activities associated with the planned EVAs in Russian and U.S. space programs have relied almost exclusively on physical simulators. These experimental tests are expensive and time consuming. During the past few years a strong increase has been observed in the use of computer simulations due to the fast developments in computer hardware and simulation software. Based on this idea, an effort to develop a computational simulation system to model human dynamic motion for EVA is initiated. This study focuses on the simulation of an astronaut moving the orbital replaceable units into the worksites or removing them from the worksites. Our physics-based methodology helps fill the gap in quantitative analysis of astronaut EVA by providing a multisegment human arm model. Simulation work described in the study improves on the realism of previous efforts, incorporating joint stops to account for the physiological limits of range of motion. To demonstrate the utility of this approach human arm model is simulated virtually using ADAMS/LifeMOD® software. Kinematic mechanism for the astronaut’s task is studied from joint angles and torques. Simulation results obtained is validated with numerical simulation based on the principles of Newton-Euler method. Torques determined using mathematical model are compared among the subjects to know the grace and consistency of the task performed. We conclude that due to uncertain nature of exploration-class EVA, a virtual model developed using multibody dynamics approach offers significant advantages over traditional human modeling approaches.
Abstract: We assume an IoT-based smart-home environment where the on-off status of each of the electrical appliances including the room lights can be recognized in a real time by monitoring and analyzing the smart meter data. At any moment in such an environment, we can recognize what the household or the user is doing by referring to the status data of the appliances. In this paper, we focus on a smart-home service that is to activate a robot vacuum cleaner at right time by recognizing the user situation, which requires a situation-aware model that can distinguish the situations that allow vacuum cleaning (Yes) from those that do not (No). We learn as our candidate models a few classifiers such as naïve Bayes, decision tree, and logistic regression that can map the appliance-status data into Yes and No situations. Our training and test data are obtained from simulations of user behaviors, in which a sequence of user situations such as cooking, eating, dish washing, and so on is generated with the status of the relevant appliances changed in accordance with the situation changes. During the simulation, both the situation transition and the resulting appliance status are determined stochastically. To compare the performances of the aforementioned classifiers we obtain their learning curves for different types of users through simulations. The result of our empirical study reveals that naïve Bayes achieves a slightly better classification accuracy than the other compared classifiers.
Abstract: Control of diesel engine’s air path has drawn a lot of attention due to its multi input-multi output, closed coupled, non-linear relation. Today, precise control of amount of air to be combusted is a must in order to meet with tight emission limits and performance targets. In this study, passenger car size diesel engine is modeled by AVL Boost RT, and then simulated with standard, industry level PID controllers. Finally, linear model predictive control is designed and simulated. This study shows the importance of modeling and control of diesel engines with flexible algorithm development in computer based systems.
Abstract: This research focuses on assessing the ground water quality of Northern Lebanon affected by saline water intrusion. The chemical, physical and microbiological parameters were collected in various seasons spanning over the period of two years. Results were assessed using Geographic Information System (GIS) due to its visual capabilities in presenting the pollution extent in the studied region. Future projections of the excessive pumping were also simulated using GIS in order to assess the extent of the problem of saline intrusion in the near future.
Abstract: This paper presents Differential Evolution Algorithm (DEA) based Variable Structure Position Control (VSPC) of Laboratory DC servomotor (LDCSM). DEA is employed for the optimal tuning of Variable Structure Control (VSC) parameters for position control of a DC servomotor. The VSC combines the techniques of Sliding Mode Control (SMC) that gives the advantages of small overshoot, improved step response characteristics, faster dynamic response and adaptability to plant parameter variations, suppressed influences of disturbances and uncertainties in system behavior. The results of the simulation responses of the VSC parameters adjustment by DEA were performed in Matlab Version 2010a platform and yield better dynamic performance compared with the untuned VSC designed.
Abstract: This paper compares the findings of two studies conducted to determine the effectiveness of simulation-based, hands-on and feedback mechanism on students learning by answering the following questions: 1). Does the use of simulation improve students’ learning outcomes? 2). How do students perceive the instructional design features embedded in the simulation program such as exploration and scaffolding support in learning new concepts? 3.) What is the effect of feedback mechanisms on students’ learning in the use of simulation-based labs? The paper also discusses the other aspects of findings which reveal that simulation by itself is not very effective in promoting student learning. Simulation becomes effective when it is followed by hands-on activity and feedback mechanisms. Furthermore, the paper presents recommendations for improving student learning through the use of simulation-based, hands-on, and feedback-based teaching methodologies.
Abstract: Fault diagnosis of Linear Parameter-Varying (LPV)
system using an adaptive Kalman filter is proposed. The LPV model
is comprised of scheduling parameters, and the emulator parameters.
The scheduling parameters are chosen such that they are capable of
tracking variations in the system model as a result of changes in the
operating regimes. The emulator parameters, on the other hand,
simulate variations in the subsystems during the identification phase
and have negligible effect during the operational phase. The nominal
model and the influence vectors, which are the gradient of the feature
vector respect to the emulator parameters, are identified off-line from
a number of emulator parameter perturbed experiments. A Kalman
filter is designed using the identified nominal model. As the system
varies, the Kalman filter model is adapted using the scheduling
variables. The residual is employed for fault diagnosis. The
proposed scheme is successfully evaluated on simulated system as
well as on a physical process control system.
Abstract: To increase the temperature contrast in thermal
images, the characteristics of the electrical conductivity and thermal
imaging modalities can be combined. In this experimental study, it is
objected to observe whether the temperature contrast created by the
tumor tissue can be improved just due to the current application
within medical safety limits. Various thermal breast phantoms are
developed to simulate the female breast tissue. In vitro experiments
are implemented using a thermal infrared camera in a controlled
manner. Since experiments are implemented in vitro, there is no
metabolic heat generation and blood perfusion. Only the effects and
results of the electrical stimulation are investigated. Experimental
study is implemented with two-dimensional models. Temperature
contrasts due to the tumor tissues are obtained. Cancerous tissue is
determined using the difference and ratio of healthy and tumor
images. 1 cm diameter single tumor tissue causes almost 40 °mC
temperature contrast on the thermal-breast phantom. Electrode
artifacts are reduced by taking the difference and ratio of background
(healthy) and tumor images. Ratio of healthy and tumor images show
that temperature contrast is increased by the current application.
Abstract: This paper presents the confidence intervals for the
effect size base on bootstrap resampling method. The meta-analytic
confidence interval for effect size is proposed that are easy to
compute. A Monte Carlo simulation study was conducted to compare
the performance of the proposed confidence intervals with the
existing confidence intervals. The best confidence interval method
will have a coverage probability close to 0.95. Simulation results
have shown that our proposed confidence intervals perform well in
terms of coverage probability and expected length.
Abstract: Wireless Body Area Network (WBAN) is a short-range
wireless communication around human body for various applications
such as wearable devices, entertainment, military, and especially
medical devices. WBAN attracts the attention of continuous health
monitoring system including diagnostic procedure, early detection of
abnormal conditions, and prevention of emergency situations.
Compared to cellular network, WBAN system is more difficult to
control inter- and inner-cell interference due to the limited power,
limited calculation capability, mobility of patient, and
non-cooperation among WBANs.
In this paper, we compare the performance of resource allocation
scheme based on several Pseudo Orthogonal Codewords (POCs) to
mitigate inter-WBAN interference. Previously, the POCs are widely
exploited for a protocol sequence and optical orthogonal code. Each
POCs have different properties of auto- and cross-correlation and
spectral efficiency according to its construction of POCs. To identify
different WBANs, several different pseudo orthogonal patterns based
on POCs exploits for resource allocation of WBANs. By simulating
these pseudo orthogonal resource allocations of WBANs on
MATLAB, we obtain the performance of WBANs according to
different POCs and can analyze and evaluate the suitability of POCs
for the resource allocation in the WBANs system.
Abstract: The increasing demand of electric power is giving an
emphasis on the need for the maximum utilization of renewable
energy sources. On the other hand maintaining power quality to
satisfaction of utility is an essential requirement. In this paper the
design aspects of a Unified Power Quality Conditioner integrated
with photovoltaic system in a distributed generation is presented. The
proposed system consist of series inverter, shunt inverter are
connected back to back on the dc side and share a common dc-link
capacitor with Distributed Generation through a boost converter. The
primary task of UPQC is to minimize grid voltage and load current
disturbances along with reactive and harmonic power compensation.
In addition to primary tasks of UPQC, other functionalities such as
compensation of voltage interruption and active power transfer to the
load and grid in both islanding and interconnected mode have been
addressed. The simulation model is design in MATLAB/ Simulation
environment and the results are in good agreement with the published
work.
Abstract: In recent years, the use of renewable energy resources
instead of pollutant fossil fuels and other forms has increased.
Photovoltaic generation is becoming increasingly important as a
renewable resource since it does not cause in fuel costs, pollution,
maintenance, and emitting noise compared with other alternatives
used in power applications. In this paper, Perturb and Observe and
Incremental Conductance methods are used to improve energy
conversion efficiency under different environmental conditions. PI
controllers are used to control easily DC-link voltage, active and
reactive currents. The whole system is simulated under standard
climatic conditions (1000 W/m2, 250C) in MATLAB and the
irradiance is varied from 1000 W/m2 to 300 W/m2. The use of PI
controller makes it easy to directly control the power of the grid
connected PV system. Finally the validity of the system will be
verified through the simulations in MATLAB/Simulink environment.
Abstract: As the number of fire accidents is gradually raising, many studies have been reported on evacuation. Previous studies have mostly focused on evaluating the safety of evacuation and the risk of fire in particular buildings. However, studies on effects of various parameters on evacuation have not been nearly done. Therefore, this paper aims at observing evacuation time under the effect of fire initiated location. In this study, evacuation simulations are performed on a 5-floor building located in Seoul, South Korea using the commercial program, Fire Dynamics Simulator with Evacuation (FDS+EVAC). Only the fourth and fifth floors are modeled with an assumption that fire starts in a room located on the fourth floor. The parameter for evacuation simulations is location of fire initiation to observe the evacuation time and safety. Results show that the location of fire initiation is closer to exit, the more time is taken to evacuate. The case having the nearest location of fire initiation to exit has the lowest ratio of successful occupants to the total occupants. In addition, for safety evaluation, the evacuation time calculated from computer simulation model is compared with the tolerable evacuation time according to code in Japan. As a result, all cases are completed within the tolerable evacuation time. This study allows predicting evacuation time under various conditions of fire and can be used to evaluate evacuation appropriateness and fire safety of building.
Abstract: This paper details the progress made in the development of the different state-of-the-art aerodynamic tools for the analysis of vertical axis wind turbines including the flow simulation around the blade, viscous flow, stochastic wind, and dynamic stall effects. The paper highlights the capabilities of the developed wind turbine aerodynamic codes over the last thirty years which are currently being used in North America and Europe by Sandia Laboratories, FloWind, IMST Marseilles, and Hydro-Quebec among others. The aerodynamic codes developed at Ecole Polytechnique de Montreal, Canada, represent valuable tools for simulating the flow around wind turbines including secondary effects. Comparison of theoretical results with experimental data have shown good agreement. The strength of the aerodynamic codes based on Double-Multiple Stream tube model (DMS) lies in its simplicity, accuracy, and ability to analyze secondary effects that interfere with wind turbine aerodynamic calculations.
Abstract: In this work, we propose an algorithm developed under Python language for the modeling of ordinary scalar Bessel beams and their discrete superpositions and subsequent calculation of optical forces exerted over dielectric spherical particles. The mathematical formalism, based on the generalized Lorenz-Mie theory, is implemented in Python for its large number of free mathematical (as SciPy and NumPy), data visualization (Matplotlib and PyJamas) and multiprocessing libraries. We also propose an approach, provided by a synchronized Software as Service (SaaS) in cloud computing, to develop a user interface embedded on a mobile application, thus providing users with the necessary means to easily introduce desired unknowns and parameters and see the graphical outcomes of the simulations right at their mobile devices. Initially proposed as a free Android-based application, such an App enables data post-processing in cloud-based architectures and visualization of results, figures and numerical tables.
Abstract: Tsunami and inundation modelling due to far field tsunami propagation in a limited area is a very challenging numerical task because it involves many aspects such as the formation of various types of waves and the irregularities of coastal boundaries. To compute the effect of far field tsunami and extent of inland inundation due to far field tsunami along the coastal belts of west coast of Malaysia and Southern Thailand, a formulated boundary condition and a moving boundary condition are simultaneously used. In this study, a boundary fitted curvilinear grid system is used in order to incorporate the coastal and island boundaries accurately as the boundaries of the model domain are curvilinear in nature and the bending is high. The tsunami response of the event 26 December 2004 along the west open boundary of the model domain is computed to simulate the effect of far field tsunami. Based on the data of the tsunami source at the west open boundary of the model domain, a boundary condition is formulated and applied to simulate the tsunami response along the coastal and island boundaries. During the simulation process, a moving boundary condition is initiated instead of fixed vertical seaside wall. The extent of inland inundation and tsunami propagation pattern are computed. Some comparisons are carried out to test the validation of the simultaneous use of the two boundary conditions. All simulations show excellent agreement with the data of observation.
Abstract: Soil improvement using vibro stone column techniques consists of two main parts: (1) the installed load bearing columns of well-compacted, coarse-grained material and (2) the improvements to the surrounding soil due to vibro compaction. Extensive research work has been carried out over the last 20 years to understand the improvement in the composite foundation performance due to the second part mentioned above. Nevertheless, few of these studies have tried to quantify some of the key design parameters, namely the changes in the stiffness and stress state of the treated soil, or have consider these parameters in the design and calculation process. Consequently, empirical and conservative design methods are still being used by ground improvement companies with a significant variety of results in engineering practice. Two-dimensional finite element study to develop an axisymmetric model of a single stone column reinforced foundation was performed using PLAXIS 2D AE to quantify the effect of the vibro installation of this column in soft saturated clay. Settlement and bearing performance were studied as an essential part of the design and calculation of the stone column foundation. Particular attention was paid to the large deformation in the soft clay around the installed column caused by the lateral expansion. So updated mesh advanced option was taken in the analysis. In this analysis, different degrees of stone column lateral expansions were simulated and numerically analyzed, and then the changes in the stress state, stiffness, settlement performance and bearing capacity were quantified. It was found that application of radial expansion will produce a horizontal stress in the soft clay mass that gradually decrease as the distance from the stone column axis increases. The excess pore pressure due to the undrained conditions starts to dissipate immediately after finishing the column installation, allowing the horizontal stress to relax. Changes in the coefficient of the lateral earth pressure K ٭, which is very important in representing the stress state, and the new stiffness distribution in the reinforced clay mass, were estimated. More encouraging results showed that increasing the expansion during column installation has a noticeable effect on improving the bearing capacity and reducing the settlement of reinforced ground, So, a design method should include this significant effect of the applied lateral displacement during the stone column instillation in simulation and numerical analysis design.
Abstract: Makishima and Mackenzie model was used to
simulation of acoustic properties (longitudinal and shear ultrasonic
wave velocities, elastic moduli theoretically for many tellurite and
borate glasses. The model was proposed mainly depending on the
values of the experimentally measured density, which are obtained
before. In this search work, we are trying to obtain the values of
densities of amorphous glasses (as the density depends on the
geometry of the network structure of these glasses). In addition, the
problem of simulating the slope of linear regression between the
experimentally determined bulk modulus and the product of packing
density and experimental Young's modulus, were solved in this
search work. The results showed good agreement between the
experimentally measured values of densities and both ultrasonic wave
velocities, and those theoretically determined.
Abstract: Natural gas sweetening process is a controlled process that must be done at maximum efficiency and with the highest quality. In this work, due to complexity and non-linearity of the process, the H2S gas separation and the intelligent fuzzy controller, which is used to enhance the process, are simulated in MATLAB – Simulink. New design of fuzzy control for Gas Separator is discussed in this paper. The design is based on the utilization of linear state-estimation to generate the internal knowledge-base that stores input-output pairs. The obtained input/output pairs are then used to design a feedback fuzzy controller. The proposed closed-loop fuzzy control system maintains the system asymptotically-stability while it enhances the system time response to achieve better control of the concentration of the output gas from the tower. Simulation studies are carried out to illustrate the Gas Separator system performance.
Abstract: Pipelines are extensively used engineering structures
which convey fluid from one place to another. Most of the time,
pipelines are placed underground and are encumbered by soil weight
and traffic loads. Corrosion of pipe material is the most common
form of pipeline deterioration and should be considered in both the
strength and serviceability analysis of pipes.
The study in this research focuses on concrete pipes in sewage
systems (concrete sewers). This research firstly investigates how to
involve the effect of corrosion as a time dependent process of
deterioration in the structural and failure analysis of this type of pipe.
Then three probabilistic time dependent reliability analysis methods
including the first passage probability theory, the gamma distributed
degradation model and the Monte Carlo simulation technique are
discussed and developed. Sensitivity analysis indexes which can be
used to identify the most important parameters that affect pipe failure
are also discussed.
The reliability analysis methods developed in this paper contribute
as rational tools for decision makers with regard to the strengthening
and rehabilitation of existing pipelines. The results can be used to
obtain a cost-effective strategy for the management of the sewer
system.