Abstract: There is a growing interest in the use of ultrasonic speckle tracking for biomedical image formation of tissue deformation. Speckle tracking is angle independent and has an ability to differentiate soft tissue into benign and malignant regions. In this paper a simulation model for dynamic ultrasound scatterer is presented. The model composes Field-II ultrasonic scatterers and FEM (ANSYS-11) nodes as a regional tissue deformation. A performance evaluation is presented on axial displacement and strain fields estimation of a uniformly elastic model, using speckle tracking based 1D cross-correlation of optimally segmented pre and post-deformation frames. Optimum correlation window length is investigated in terms of highest signal-to-noise ratio (SNR) for a selected region of interest of a smoothed displacement field. Finally, gradient based strain field of both smoothed and non-smoothed displacement fields are compared. Simulation results from the model are shown to compare favorably with FEM results.
Abstract: Axial compression tests are performed on circular tubes made of Aluminum EN AW 6060 (AlMgSi0.5 alloy) in T66 state. All the received tubes have the uniform outer diameter of 40mm and thickness of 1.5mm. Two different lengths 100mm and 200mm are used in the analysis. After performing compression tests on the uniform tube, important crashworthy parameters like peak force, average force, crush efficiency and energy absorption are measured. The present paper has given importance to increase the percentage of crush efficiency without decreasing the value energy absorption of a tube, so a circumferential notch was introduced on the top section of the tube. The effects of position and cut-out lengths of a circumferential notch on the crush efficiency are well explained with relative deformation modes and force-displacement curves. The numerical simulations were carried on the software tool ANSYS/LS-DYNA. It is seen that the numerical results are reasonably good in agreement with the experimental results.
Abstract: This paper investigates the suitability of Latin Hypercube sampling (LHS) for composite electric power system reliability analysis. Each sample generated in LHS is mapped into an equivalent system state and used for evaluating the annualized system and load point indices. DC loadflow based state evaluation model is solved for each sampled contingency state. The indices evaluated are loss of load probability, loss of load expectation, expected demand not served and expected energy not supplied. The application of the LHS is illustrated through case studies carried out using RBTS and IEEE-RTS test systems. Results obtained are compared with non-sequential Monte Carlo simulation and state enumeration analytical approaches. An error analysis is also carried out to check the LHS method’s ability to capture the distributions of the reliability indices. It is found that LHS approach estimates indices nearer to actual value and gives tighter bounds of indices than non-sequential Monte Carlo simulation.
Abstract: In many practical applications in various areas, such as engineering, science and social science, it is known that there exist bounds on the values of unknown parameters. For example, values of some measurements for controlling machines in an industrial process, weight or height of subjects, blood pressures of patients and retirement ages of public servants. When interval estimation is considered in a situation where the parameter to be estimated is bounded, it has been argued that the classical Neyman procedure for setting confidence intervals is unsatisfactory. This is due to the fact that the information regarding the restriction is simply ignored. It is, therefore, of significant interest to construct confidence intervals for the parameters that include the additional information on parameter values being bounded to enhance the accuracy of the interval estimation. Therefore in this paper, we propose a new confidence interval for the coefficient of variance where the population mean and standard deviation are bounded. The proposed interval is evaluated in terms of coverage probability and expected length via Monte Carlo simulation.
Abstract: In this paper, we propose two new confidence intervals for the inverse of a normal mean with a known coefficient of variation. One of new confidence intervals for the inverse of a normal mean with a known coefficient of variation is constructed based on the pivotal statistic Z where Z is a standard normal distribution and another confidence interval is constructed based on the generalized confidence interval, presented by Weerahandi. We examine the performance of these confidence intervals in terms of coverage probabilities and average lengths via Monte Carlo simulation.
Abstract: Mostly, pedestrian-car accidents occurred at a
signalized interaction is because pedestrians cannot across the
intersection safely within the green light. From the viewpoint of
pedestrian, there might have two reasons. The first one is pedestrians
cannot speed up to across the intersection, such as the elders. The other
reason is pedestrians do not sense that the signal phase is going to
change and their right-of-way is going to lose. Developing signal logic
to protect pedestrian, who is crossing an intersection is the first
purpose of this study. Another purpose of this study is improving the
reliability and reduce delay of public transportation service. Therefore,
bus preemption is also considered in the designed signal logic. In this
study, the traffic data of the intersection of Chong-Qing North Road
and Min-Zu West Road, Taipei, Taiwan, is employed to calibrate and
validate the signal logic by simulation. VISSIM 5.20, which is a
microscopic traffic simulation software, is employed to simulate the
signal logic. From the simulated results, the signal logic presented in
this study can protect pedestrians crossing the intersection
successfully. The design of bus preemption can reduce the average
delay. However, the pedestrian safety and bus preemptive signal will
influence the average delay of cars largely. Thus, whether applying the
pedestrian safety and bus preemption signal logic to an isolated
intersection or not should be evaluated carefully.
Abstract: According to previous studies, some muscles present a non-homogeneous spatial distribution of its muscle fiber types and motor unit types. However, available muscle models only deal with muscles with homogeneous distributions. In this paper, a new architecture muscle model is proposed to permit the construction of non-uniform distributions of muscle fibers within the muscle cross section. The idea behind is the use of a motor unit placement algorithm that controls the spatial overlapping of the motor unit territories of each motor unit type. Results show the capabilities of the new algorithm to reproduce arbitrary muscle fiber type distributions.
Abstract: An explicit axisymmetrical FE methodology is
developed here to study the particle temperature arising in WC-Co
particle on an AISI 1045 steel substrate. Parameters of constitutive
Johnson-cook model were used for simulation. The results show that
particle velocity and kinetic energy have important role in
temperature arising of particles.
Abstract: This paper describes the design of new method of
propagation delay measurement in micro and nanostructures during
characterization of ASIC standard library cell. Providing more
accuracy timing information about library cell to the design team we
can improve a quality of timing analysis inside of ASIC design flow
process. Also, this information could be very useful for semiconductor
foundry team to make correction in technology process. By
comparison of the propagation delay in the CMOS element and result
of analog SPICE simulation. It was implemented as digital IP core for
semiconductor manufacturing process. Specialized method helps to
observe the propagation time delay in one element of the standard-cell
library with up-to picoseconds accuracy and less. Thus, the special
useful solutions for VLSI schematic to parameters extraction, basic
cell layout verification, design simulation and verification are
announced.
Abstract: This work presents a theoretical investigation of the
simultaneous absorption of CO2 and H2S into aqueous solutions of
MDEA and DEA. In this process the acid components react
with the basic alkanolamine solution via an exothermic,
reversible reaction in a gas/liquid absorber. The use of amine
solvents for gas sweetening has been investigated using
process simulation programs called HYSYS and ASPEN. We
use Electrolyte NRTL and Amine Package and Amines
(experimental) equation of state. The effects of temperature and
circulation rate and amine concentration and packed column and
murphree efficiency on the rate of absorption were studied.
When lean amine flow and concentration increase, CO2 and H2S
absorption increase too. With the improvement of inlet amine
temperature in absorber, CO2 and H2S penetrate to upper stages of
absorber and absorption of acid gases in absorber decreases. The CO2
concentration in the clean gas can be greatly influenced by the
packing height, whereas for the H2S concentration in the clean gas the
packing height plays a minor role. HYSYS software can not
estimate murphree efficiency correctly and it applies the same
contributions in all diagrams for HYSYS software. By
improvement in murphree efficiency, maximum temperature
of absorber decrease and the location of reaction transfer to the
stages of bottoms absorber and the absorption of acid gases
increase.
Abstract: In the present study, computational fluid dynamics
(CFD) simulation has been executed to investigate the transition
boundaries of different flow patterns for moderately viscous oil-water
(viscosity ratio 107, density ratio 0.89 and interfacial tension of 0.032
N/m.) two-phase flow through a horizontal pipeline with internal
diameter and length of 0.025 m and 7.16 m respectively. Volume of
Fluid (VOF) approach including effect of surface tension has been
employed to predict the flow pattern. Geometry and meshing of the
present problem has been drawn using GAMBIT and ANSYS
FLUENT has been used for simulation. A total of 47037 quadrilateral
elements are chosen for the geometry of horizontal pipeline. The
computation has been performed by assuming unsteady flow,
immiscible liquid pair, constant liquid properties, co-axial flow and a
T-junction as entry section. The simulation correctly predicts the
transition boundaries of wavy stratified to stratified mixed flow.
Other transition boundaries are yet to be simulated. Simulated data
has been validated with our own experimental results.
Abstract: Economic models are complex dynamic systems with a lot of uncertainties and fuzzy data. Conventional modeling approaches using well known methods and techniques cannot provide realistic and satisfactory answers to today-s challenging economic problems. Qualitative modeling using fuzzy logic and intelligent system theories can be used to model macroeconomic models. Fuzzy Cognitive maps (FCM) is a new method been used to model the dynamic behavior of complex systems. For the first time FCMs and the Mamdani Model of Intelligent control is used to model macroeconomic models. This new model is referred as the Mamdani Rule-Based Fuzzy Cognitive Map (MBFCM) and provides the academic and research community with a new promising integrated advanced computational model. A new economic model is developed for a qualitative approach to Macroeconomic modeling. Fuzzy Controllers for such models are designed. Simulation results for an economic scenario are provided and extensively discussed
Abstract: Three-dimensional geometric models have been used
to present architectural and engineering works, showing their final
configuration. When the clarification of a detail or the constitution of
a construction step in needed, these models are not appropriate. They
do not allow the observation of the construction progress of a
building. Models that could present dynamically changes of the
building geometry are a good support to the elaboration of projects.
Techniques of geometric modeling and virtual reality were used to
obtain models that could visually simulate the construction activity.
The applications explain the construction work of a cavity wall and a
bridge. These models allow the visualization of the physical
progression of the work following a planned construction sequence,
the observation of details of the form of every component of the
works and support the study of the type and method of operation of
the equipment applied in the construction. These models presented
distinct advantage as educational aids in first-degree courses in Civil
Engineering. The use of Virtual Reality techniques in the
development of educational applications brings new perspectives to
the teaching of subjects related to the field of civil construction.
Abstract: This paper deals with modeling and parameter
identification of nonlinear systems described by Hammerstein model
having Piecewise nonlinear characteristics such as Dead-zone
nonlinearity characteristic. The simultaneous use of both an easy
decomposition technique and the triangular basis functions leads to a
particular form of Hammerstein model. The approximation by using
Triangular basis functions for the description of the static nonlinear
block conducts to a linear regressor model, so that least squares
techniques can be used for the parameter estimation. Singular Values
Decomposition (SVD) technique has been applied to separate the
coupled parameters. The proposed approach has been efficiently
tested on academic examples of simulation.
Abstract: The underground shopping mall has the constructional
problem of the fire evacuation. Also, the people sometimes lose their
direction and information of current time in the mall. If the
emergencies such as terrorist explosions or gas explosions are
happened, they have to go out soon. Under such circumstances, inside
of the mall has high risk for life. In this research, the authors propose a
way that he/she can go out from the underground shopping mall
quickly. If the narrow exits are discovered by using active RFID
(Radio Frequency Identification) tags and using cellular phones, they
can evacuate as soon as possible. To verify this hypothesis, the authors
design the model and carry out the agent-based simulation. They treat,
as a case study, the Tenjin mall in Fukuoka Prefecture in Japan. The
result of the simulation is that the case of the pedestrian with using
active RFID tags and cellular phones reduced the amount of time to
spend on the evacuation. Even if the diffusion of RFID tags and
cellular phones was not perfect, they could show the effectiveness of
reducing the time of evacuation.
Abstract: This article deals with numerical simulation of the
floor heating convector in 3D. Numerical simulation is focused on
cooling mode of the floor heating convector. Geometrical model
represents section of the heat exchanger – two fins with the gap
between, pipes are not involved. Two types of fin are examined –
sinusoidal and angular shape with different fin spacing. Results of fin
spacing in case of constant Reynolds number are presented. For the
numerical simulation was used commercial software Ansys Fluent.
Abstract: A dynamic of Bertrand duopoly game is analyzed, where players use different production methods and choose their prices with bounded rationality. The equilibriums of the corresponding discrete dynamical systems are investigated. The stability conditions of Nash equilibrium under a local adjustment process are studied. The stability conditions of Nash equilibrium under a local adjustment process are studied. The stability of Nash equilibrium, as some parameters of the model are varied, gives rise to complex dynamics such as cycles of higher order and chaos. On this basis, we discover that an increase of adjustment speed of bounded rational player can make Bertrand market sink into the chaotic state. Finally, the complex dynamics, bifurcations and chaos are displayed by numerical simulation.
Abstract: To reveal the temperature field distribution of disc
brake in downward belt conveyor, mathematical models of heat
transfer for disc brake were established combined with heat transfer
theory. Then, the simulation process was stated in detail and the
temperature field of disc brake under conditions of dynamic speed and
dynamic braking torque was numerically simulated by using ANSYS
software. Finally the distribution and variation laws of temperature
field in the braking process were analyzed. Results indicate that the
maximum surface temperature occurs at a time before the brake end
and there exist large temperature gradients in both radial and axial
directions, while it is relatively small in the circumferential direction.
Abstract: The presented work is motivated by a French law
regarding nuclear waste management. A new conceptual Accelerator
Driven System (ADS) designed for the Minor Actinides (MA)
transmutation has been assessed by numerical simulation. The
MUltiple Spallation Target (MUST) ADS combines high thermal power (up to 1.4 GWth) and high specific power. A 30 mA and 1
GeV proton beam is divided into three secondary beams transmitted on three liquid lead-bismuth spallation targets. Neutron and thermalhydraulic
simulations have been performed with the code MURE, based on the Monte-Carlo transport code MCNPX. A methodology has been developed to define characteristic of the MUST ADS concept according to a specific transmutation scenario. The reference
scenario is based on a MA flux (neptunium, americium and curium)
providing from European Fast Reactor (EPR) and a plutonium multireprocessing
strategy is accounted for. The MUST ADS reference
concept is a sodium cooled fast reactor. The MA fuel at equilibrium is mixed with MgO inert matrix to limit the core reactivity and
improve the fuel thermal conductivity. The fuel is irradiated over five
years. Five years of cooling and two years for the fuel fabrication are
taken into account. The MUST ADS reference concept burns about 50% of the initial MA inventory during a complete cycle. In term of
mass, up to 570 kg/year are transmuted in one concept. The methodology to design the MUST ADS and to calculate fuel
composition at equilibrium is precisely described in the paper. A detailed fuel evolution analysis is performed and the reference scenario is compared to a scenario where only americium transmutation is performed.
Abstract: This paper presents a new problem solving approach
that is able to generate optimal policy solution for finite-state
stochastic sequential decision-making problems with high data
efficiency. The proposed algorithm iteratively builds and improves
an approximate Markov Decision Process (MDP) model along with
cost-to-go value approximates by generating finite length trajectories
through the state-space. The approach creates a synergy between an
approximate evolving model and approximate cost-to-go values to
produce a sequence of improving policies finally converging to the
optimal policy through an intelligent and structured search of the
policy space. The approach modifies the policy update step of the
policy iteration so as to result in a speedy and stable convergence to
the optimal policy. We apply the algorithm to a non-holonomic
mobile robot control problem and compare its performance with
other Reinforcement Learning (RL) approaches, e.g., a) Q-learning,
b) Watkins Q(λ), c) SARSA(λ).