Search

A safety analysis method for Petri nets is proposed in the paper. The idea relies on the computation of the state machine components cover computed with the linear algebra technique. Contrary to the traditional algorithms the presented method is an approximate one. The proposed idea has been verified experimentally, and a brief analysis of the obtained results is presented. [ABSTRACT FROM AUTHOR]

This paper presents the comparative studies on heat transfer coefficient for circular and non-circular duct like square, elliptical and triangular section using computational fluid dynamics simulation package. The forced convection with turbulent flow is very complicated and analyzed through CFD simulation. The geometry model developed for four cases and meshed processed using CFX13 software package for the given boundary conditions. CFD simulation is carried out with the constant heat flux on the wall to compute the heat transfer coefficient and compared with experimental and correlation method. It is concluded from the analysis elliptical cross section having more heat transfer co-efficient value of 153W/m2K when compared to circular having heat transfer coefficient value of 147W/m²K due to increase in the surface of the elliptical section when compared to circular. [ABSTRACT FROM AUTHOR]

This paper introduces a computational method for an ellipsoidal truncated modeling of the classic three-dimensional normal distribution. We suggest a method of truncation in which the limits are determined by a successive minimization of the error, under the conditions in which the corresponding probability density approximates ever better the numeric data. [ABSTRACT FROM AUTHOR]

The future integration on Tore Supra (TS) of the new Ion Cyclotron Heating (ICRH) ITER-like prototype antenna will be performed to achieve the final validation within plasma conditions. Along the few years of developments and electrical optimizations, this antenna went through series of thermo/mechanical and electrical tests. This paper presents the latest electrical results of the ITER Like antenna under vacuum condition inside the test bed. High RF power (60 kW) for 2 seconds pulses were performed, the paper present the first electrical performance results and focused on the experimental measurements of the current monitoring compared to electrical simulations. [ABSTRACT FROM AUTHOR]

Covid-19 can be transmitted from humans to humans through close contact and droplets. It is allegedly, according to experts, also possible through the air. The people most at risk of contracting this disease are in close contact with Covid-19 patients, namely medical personnel who treat Covid-19 patients. One of the main procedures is how to mobilize Covid-19 patients, which in this case requires specialized systems and equipment to avoid direct exposure to the virus. The problem is the transmission of the infection can occur during the evacuation of Covid-19 patients by the medical team. In general, a stretcher is an imported product. It is complicated to obtain in the condition of the Covid-19 pandemic, nor is there a stretcher with a unique design for the evacuation of Covid-19 patients that can prevent exposure to the virus to medical personnel and the surrounding environment. Furthermore, it is striving to produce a stretcher by the domestic industry. The availability of a unique stretcher design to remove Covid-19 patients can prevent exposure to the virus to medical personnel. This paper discusses the stretcher's structure and material for the transfer of Covid-19 patients. The research methodology used is direct observation of stretcher designs that have been sold commercially. Furthermore, a numerical simulation process is carried out by statically loading the stretcher structure. This research output is in the form of the analysis of stretcher's structure and material for Covid-19 patients, including variations of stretcher's design and material of the pipe structure. [ABSTRACT FROM AUTHOR]

In the paper an analysis of fluid flow and heat transfer of a power-law fluid in an internally finned tube with different fin length is conducted. Nonlinear momentum equation of a power-law fluid flow and nonlinear energy equation are solved using the Picard iteration method. Then on each iteration step the solution of inhomogeneous equation consists of two parts: the general solution and the particular solution. Firstly the particular solution is obtained by interpolation of the inhomogeneous term by means of the radial basis functions and monomials. Then the general solution is obtained using the method of fundamental solutions and by fulfilling boundary conditions. [ABSTRACT FROM AUTHOR]

We have applied the finite difference time domain (FDTD) method with the supersymmetric quantum mechanics (SUSY-QM) procedure to determine excited energies of one dimensional quantum systems. The theoretical basis of FDTD, SUSY-QM, a numerical algorithm and an illustrative example for a particle in a one dimensional square-well potential were given in this paper. It was shown that the numerical results were in excellent agreement with theoretical results. Numerical errors produced by the SUSY-QM procedure was due to errors in estimations of superpotentials and supersymmetric partner potentials. [ABSTRACT FROM AUTHOR]

Monte Carlo (MC) is one of the powerful techniques for simulation in x-ray imaging. MC method can simulate the radiation transport within matter with high accuracy and provides a natural way to simulate radiation transport in complex systems. One of the codes based on MC algorithm that are widely used for radiographic images simulation is MC-GPU, a codes developed by Andrea Basal. This study was aimed to investigate the time computation of x-ray imaging simulation in GPU (Graphics Processing Unit) compared to a standard CPU (Central Processing Unit). Furthermore, the effect of physical parameters to the quality of radiographic images and the comparison of image quality resulted from simulation in the GPU and CPU are evaluated in this paper. The simulations were run in CPU which was simulated in serial condition, and in two GPU with 384 cores and 2304 cores. In simulation using GPU, each cores calculates one photon, so, a large number of photon were calculated simultaneously. Results show that the time simulations on GPU were significantly accelerated compared to CPU. The simulations on the 2304 core of GPU were performed about 64 -114 times faster than on CPU, while the simulation on the 384 core of GPU were performed about 20 - 31 times faster than in a single core of CPU. Another result shows that optimum quality of images from the simulation was gained at the history start from 108 and the energy from 60 Kev to 90 Kev. Analyzed by statistical approach, the quality of GPU and CPU images are relatively the same. [ABSTRACT FROM AUTHOR]

Rapid, realistic nondestructive evaluation (NDE) simulation tools can aid in inspection optimization and prediction of inspectability for advanced aerospace materials and designs. NDE simulation tools may someday aid in the design and certification of aerospace components; potentially shortening the time from material development to implementation by industry and government. Furthermore, ultrasound modeling and simulation are expected to play a significant future role in validating the capabilities and limitations of guided wave based structural health monitoring (SHM) systems. The current state-of-the-art in ultrasonic NDE/SHM simulation is still far from the goal of rapidly simulating damage detection techniques for large scale, complex geometry composite components/vehicles containing realistic damage types. Ongoing work at NASA Langley Research Center is focused on advanced ultrasonic simulation tool development. This paper discusses challenges of simulation tool validation, optimization, and utilization for composites. Ongoing simulation tool development work is described along with examples of simulation validation and optimization challenges that are more broadly applicable to all NDE simulation tools. The paper will also discuss examples of simulation tool utilization at NASA to develop new damage characterization methods for composites, and associated challenges in experimentally validating those methods. [ABSTRACT FROM AUTHOR]

The aim of this paper is to simulate the energy levels scheme for Bismuth Germanate (BGO) doped with divalent cobalt, in order to give a reliable explanation for spectral experimental data. In the semiempirical crystal field theory we first modeled the Crystal Field Parameters (CFPs) of BGO: Cr2+ system, in the frame of Exchange Charge Model (ECM), with actually site symmetry of the impurity ions after doping. The values of CFPs depend on the geometry of doped host matrix and by parameter G of ECM. First, we optimized the geometry of undoped BGO host matrix and afterwards, that of doped BGO with divalent cobalt. The charges effect of ligands and covalence bonding between cobalt cations and oxygen anions, in the cluster approach, also were taken into account. With the obtained values of the CFPs we simulate the energy levels scheme of cobalt ions, by diagonalizing the matrix of the doped crystal Hamiltonian. Obviously, energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data and discussed. Comparison of obtained results with experimental data shows quite satisfactory, which justify the model and simulation schemes used for the title system. [ABSTRACT FROM AUTHOR]

Interactions of a vibrating string with its supports and other spatially distributed barriers play a significant role in the physics of many stringed musical instruments. It is well known that the tone of the string vibrations is determined by the string supports, and that the boundary conditions of the string termination may cause a short-lasting initial fundamental frequency shifting. Generally, this phenomenon is associated with the nonlinear modulation of the stiff string tension. The aim of this paper is to study the initial frequency glide phenomenon that is induced only by the string-barrier interaction, apart from other possible physical causes, and without the interfering effects of dissipation and dispersion. From a numerical simulation perspective, this highly nonlinear problem may present various difficulties, not the least of which is the risk of numerical instability. We propose a numerically stable and a purely kinematic model of the string-barrier interaction, which is based on the travelling wave solution of the ideal string vibration. The model is capable of reproducing the motion of the vibrating string exhibiting the initial fundamental frequency glide, which is caused solely by the complex nonlinear interaction of the string with its termination. The results presented in this paper can expand our knowledge and understanding of the timbre evolution and the physical principles of sound generation of numerous stringed instruments, such as lutes called the tambura, sitar and biwa. [ABSTRACT FROM AUTHOR]

The paper presents the results of numerical simulation of the airflow as compressible viscous heat-conducting medium in the tear-off zones arising near the surface of a high-speed aircraft having a segmental-conical shape blunted frontally to the oncoming flow. The developed mathematical model is based on solving the discrete analogs of the equations of gas dynamics on a structured computational grid for compressible viscous heat-conducting chemical neutral gas. For turbulence modeling two equation of the SST k-w model were added to Navier-Stokes equations. The presented results of modeling are compared with experimental data. The conclusions are made about the correctness of the application of the presented mathematical model for the prediction of flow parameters in tear-off zones. [ABSTRACT FROM AUTHOR]

In this paper, a frequency reconfigurable planer antenna with defected ground plane (DGP) is presented for covering two wireless standard applications bands (2 GHz and 5.2 GHz). Where a parasitic element is added on the ground plane to shift the frequency range from 5.2 GHz to 2 GHz after connect it with the ground layer. The addition of the parasitic element with the ground plane helps to switch to the lower frequency without modifying the geometry of the antenna. Additionally, it avoids the disturbance that could happen due to adding a radiation element such as PIN or varactor diode close to the antenna radiation layer. Computer Simulation Technology (CST) microwave studio is exploited to simulate the model and obtain better results. Then, the antenna was fabricated and measured practically for validation and comparing the measurement results with the simulated results. [ABSTRACT FROM AUTHOR]

Kriging models are statistical methods for approximating and estimating computer models. Kriging models have been used to replace time-consuming computer models with fast-running alternatives. Kriging models are constructed based on some assumptions. Thus, if these assumptions are not suitable and consistent with the computer model outputs, inferences and results of the Kriging models will not be accurate. Therefore, KMs need to be subjected to validation measures before using them in different areas of science. In this paper, we propose some measures that can be used for validating Kriging models. These measures are based on comparing KM predictions and computer model outputs. We investigate the performance of the proposed measures via some real examples of computer models, the Borehole model, and the Piston Simulation function. [ABSTRACT FROM AUTHOR]

A node equipped with the Intel Cascade Lake processors, which are the part of NKS-1P supercomputer of the Siberian Supercomputer Center, is investigated. An original hydrodynamic code is used to simulate the thermonuclear supernovae. The modification of numerical method for obtaining invariant numerical solutions is proposed. The weak and strong scalability, as well as, the energy efficiency in using various configurations of cores are studied. A new concept of the energy efficiency was considered together with the code efficiency in terms of the energy consumption is proposed. The results of the supercomputer simulation of the noncentral Ia supernova explosion are presented. [ABSTRACT FROM AUTHOR]

This paper presents the studies of mechanical behavior of MEMS cantilever beam made of poly-silicon material, using the coupling of three application modes (plane strain, electrostatics and the moving mesh) of COMSOL Multi-physics software. The cantilevers playing a key role in Micro Electro-Mechanical Systems (MEMS) devices (switches, resonators, etc) working under potential shock. This is why they require actuation under predetermined conditions, such as electrostatic force or inertial force. In this paper, we present mechanical behavior of a cantilever actuated by an electrostatic force. In addition to the simplification of calculations, the weight of the cantilever was not taken into account. Different parameters like beam displacement, electrostatics force and stress over the beam have been calculated by finite element method after having defining the geometry, the material of the cantilever model (fixed at one of ends but is free to move otherwise) and his operational space. [ABSTRACT FROM AUTHOR]

The aim of this paper is to show the invariance on the giant magneto-resistor sensor (GMR) output response in the measurement of different plate thicknesses when the problem is resized. To resize the problem, two different probes were projected, implemented and tested: one, with all the dimensions resized by four times the other. Both probes include a pancake coil for magnetic field sinusoidal excitation and measurements are taken with a sensitive bridge fabricated from four giant magneto-resistors (GMR). It is demonstrated, experimentally and with numerical simulation, that the same response value is obtained for two diferent plate thicknesses if dilation principle is kept in the probe's dimensions and electrical quantities. The paper uses the dilation principle to show the invariance of the magnetic field measured by a similar magnetic sensors when data is acquired with the bigger probe on a plate with a thickness four times of the plate thickness used with the smaller probe. [ABSTRACT FROM AUTHOR]

The Unified Modeling Language (UML) is an industrial standard for object-oriented software specification, which offers notational conventions for system modeling at the initial stage of software development. An actual problem is to develop a tool available for automatic generation of UML diagram from some form of the problem domain description. Authors have been introduced such a tool, called BrainTool and developed by a research group in Riga Technical University. BrainTool supports transformation of the problem domain presented as two-hemisphere model into several kinds of UML diagrams and give an ability to export these diagrams for further software development into UML compatible modeling tools and IDEs. Present paper demonstrates the comparison results of the manual UML class diagram creation for an abstract example of the football game simulation to the UML class diagram received by application of BrainTool for the same game basic scenario. These comparison results give a basis for discussion about possible improvements of the transformations offered by two-hemisphere model and potentially "richer" usage of the model for generation of the UML diagrams suitable for further software development. [ABSTRACT FROM AUTHOR]

The paper presents a work, which aims at numerical study of the wind and solar energy potential of the country. The wind/solar energy fields simulations were performed applying the 5th generation PSU/NCAR Meso- Meteorological Model MM5 for years 2000-2007 with a spatial resolution of 3 km over Bulgaria. The computer simulated data base is large and rather comprehensive. In this sense it can be considered as statistically significant ensemble. This allows statistical treatment in order various wind and solar energy potential evaluations to be retrieved from the data base. Some evaluations of the country wind and solar energy potential, based on the simulation output are demonstrated in the paper. [ABSTRACT FROM AUTHOR]

In this paper, a comparison between results furnished by a 3D FE upper bound limit analysis and experimental results for some reinforced masonry arches tested at the University of Minho (Portugal) is provided. While the delamination from arches support can be modelled only in an approximate way within limit analysis, the aim of the paper is to accurately reproduce the change in the failure mechanism observed in experimentation, due to the introduction of strengthening elements. Both experimental and numerical results showa clear change in the failure mechanism and in the corresponding ultimate peak load. A set of simulations is also performed on reinforced arches previously damaged, to investigate the role played by the reinforcement within a proper repairing procedure. Good correlation with experimental work and numerical simulations is achieved. [ABSTRACT FROM AUTHOR]

For intelligent driver assistance systems the prediction of the future driving cycle is fundamental. Recent recommendations for driving cycle standards does not provide precise information on the expected intermittent operations of the vehicle and can not be applied directly in an intelligent energy management and driving assistance system. Latest driver assistance systems require more sophisticated solutions which are able to incorporate the personal driving style. The Interval-type 2 Fuzzy System is proved to be a highly efficient tool for modeling uncertainties. In contrast to conventional Type-1 fuzzy modeling an IT2 Fuzzy System has the ability to deal with flexible with the various types of uncertainties and modeling errors simultaneously and approximates better real-life systems. This paper presents an IT2 Fuzzy System for personalized driving cycle forecasting from the measured velocity and acceleration data. The proposed method applies a Mamdani type IT2 fuzzy inference technique. The fuzzy sets and rules are built up by extracting knowledge from real driving dataset. Simulation results have shown that the presented technique is efficient and ensures satisfactory performance. [ABSTRACT FROM AUTHOR]

Computer design of materials focus on the discovery, interpretation, simulation, and organization of the microscopic interactions between atoms and molecules in condensed phases of materials. The ability to predict materials properties is a fundamental requirement of technological advances and economic competitiveness. A key component of our industrial development is the ability to invent and design novel materials. Our paper focus on computer simulation of the block copolymers structure optimization. [ABSTRACT FROM AUTHOR]

Bio-heat transfer deals with the heat transfer in the biological bodies. Human skin burn can be analyzed using the Pennes bio-heat equation which has been adopted in many commercial finite element software. Human skin burn also known as thermal burn can result from direct contact with heated object such as a hot disk, hot fluid or being exposed to radiation. Depending upon the condition and duration of exposure thermal burn may cause severe skin damage. In this paper, the three dimensional Finite Element (FE) models of human skin is developed. The burn effect on human skin under the contact with hot object or hot fluid has been analyzed. The radiation effect of a hot object on the skin burn has also been analyzed. The commercial numerical software COMSOL Multiphysics® is used for the purpose. The burn intensity in terms of degree of burn is measured with different burning conditions. The results from this analysis can be used in treatment of burn injuries. [ABSTRACT FROM AUTHOR]

This paper describes a series of experiments performed on a specific design of an explosively driven metallic plate launcher. While endeavoring to keep the detonation front, and hence the flyer, flat, the design makes use of two features that lessen the explosive mass required and reduce the propensity for generating spall in the flyer. Several variations on a standard design were fielded, not so much because they were ideally suited to the intended purpose (worst-case fragment attack simulations into cased explosive assemblies), but so that the predictions made by computer models on this slightly abnormal explosively driven system could be compared with reality. In this manner, the predictive capability of the code could be verified for subsequent design variations optimized for specific applications. The design used here had a 63.5 mm diameter flyer that was 6.35 mm thick. The leading center section (≈25 mm) was flat to better than 1 mm in all cases and to 0.1-0.2 mm in optimal situations. Greater curvature and oscillation was seen towards the periphery of the flyer. This paper concentrates on the experimental program rather than the still-ongoing computational modeling efforts. [ABSTRACT FROM AUTHOR]

In the article the new method of energy storing, using cavern gas storage system is presented. The idea drew from the Compressed Air Energy Storage systems, but use natural gas stored in salt caverns as a medium, so can be called the Compressed Natural Gas Energy Storage (CNGES). The concept of the store charging is to pump the gas from lower pressure cavern to the higher pressure one by an electric powered compressor. In the discharging mode the gas expands through the expander connected with the generator, from the high pressure cavern to the lower pressure one with the electricity production. The paper covers the dynamic model of CNGES implemented in Aspen Hysys numerical environment. The main aim of the simulation was to determine the influence of selected parameters of the store (gas initial and terminal temperature and pressure). The article covers main model assumptions, implemented methodology description, results analysis and conclusions. [ABSTRACT FROM AUTHOR]

In the study of depression, attempts to elucidate using mathematical models are not commonly performed. Therefore, in this paper, we introduce the construction of a new mathematical model for depression. We regard this study as a new method in the study on depression. Furthermore, in this paper, after constructing a mathematical model, numerical simulation is carried out, the time development of depression is visualized, and the purpose is also to capture the pathology. [ABSTRACT FROM AUTHOR]

The prediction of the hydrodynamics deriving from the sudden impact of a solid body on the water surface is of paramount importance for a wide range of engineering applications, including the design of planing or displacing crafts and of off-shore structures, aerospace applications, and energy harvesting. In this paper we review several applications of computational fluid dynamics to the hull slamming problem with particular attention to simulation setup and validation. [ABSTRACT FROM AUTHOR]

The paper presents an algorithm for constructing of synthesizing control function. This algorithm is sufficiently convenient for numerical implementation and a wide class of nonlinear nonstationary systems of ordinary differential equations, provide the passage from initial state into to origin coordinates. We obtain a constructive condition for the choice of initial state for which the passage is possible with regard of the constraints imposed on the control. We consider an problem of control of single manipulator, for which we carry numerical simulation. [ABSTRACT FROM AUTHOR]

In this paper early state star formation is investigated under three soft equations of state. The soft equations of state allow for the collapse to be followed to just beyond the isothermal limit - before the radiative pressure in the collapse becomes significant. A TVD Roe scheme is used to numerically solve the fluid equations modelling the collapse and the gravitational force is updated in place of the potential thus saving computational time. In the most extreme equation of state a distinct protostellar core is formed while the other two equations of state provide similar results. The occurrence of a rebound in the protostellar core together with the ensuing shock wave is briefly discussed. [ABSTRACT FROM AUTHOR]

The paper focus on the numerical investigation of a pump impeller combined with an axial rotor for a doubleflux pump storage. The axial rotor is investigated at variable speed between 2000 and 3000 rpm with a step size of 100 rpm, while the speed of the pump impeller is maintained constant at 2500 rpm. An improved cavitational behaviour is obtained for solution with axial rotor when the speed varies. [ABSTRACT FROM AUTHOR]

The thermal process modeling based on the operating data is effective to overcome the deficiency of mechanism modeling. In order to reduce the computational complexity of data-driven modeling, many sample selection algorithms have been used to decreasing the training dataset scale. However, traditional sampling selection algorithm may fail to cover full-scale working condition of thermal process when the dataset has large density deviations, and the sample selection criteria is often irrelevant to the modeling prediction. To overcome these issues, this paper proposes a wrapper full-scale sample selection algorithm for thermal process modeling, in which, samples will be sequentially added until there is no improvement in prediction, and sample selection criteria is the prediction evaluated by KNN regression model beforehand. It reveals that our algorithm not only cover full-scale working condition of thermal process, but also has certain superiority in model accuracy. Numerical simulation and real thermal application are conducted to validate the performance of the proposed algorithm. [ABSTRACT FROM AUTHOR]

When UHVDC has a fault, it needs to quickly cut off the load so that the entire system can keep balance. In the late period of fault dispose, it needs to recover the load step by step. The recovery strategy of millisecond load is studied in this paper. Aimed at the maximum recovery load in one step, combined with grid security constraints, the recovery model of millisecond load is built, and then solved by Genetic Algorithms. The simulation example is established to verify the effectiveness of proposed method. [ABSTRACT FROM AUTHOR]

External combustion is a phenomenon where the flame flares out of the window and burns outside. Because of the particularity of the ship's cabin structure, there is a great danger in the external combustion. In this paper, the numerical calculation and analysis of three kinds of low ceiling ship cabin fire are analyzed based on the large eddy numerical simulation technique. Through the analysis of temperature, flue gas velocity, heat flux density and so on, the external combustion phenomenon of fire development is calculated. The results show that when external combustion occurs, the amount of fuel escaping decreases with the roof height. The temperature above the window increases with the height of the ceiling. The heat flux density in the external combustion flame is mainly provided by radiation, and convection is only a small part; In the plume area there is a time period, in this time period, the convective heat flux density is greater than the radiation heat flux, this time with the ceiling height increases. No matter which ceiling height, the external combustion will seriously damage the structure of the ship after a certain period of time. The velocity distribution of the three roof is similar, but with the height of the ceiling, the area size is also increasing. [ABSTRACT FROM AUTHOR]

In this paper we propose two formulations of Cahn-Hilliard equations, which have several applications in cancer growth modeling and material science phase-field simulations. The first formulation uses one C4 partial differential equations (PDEs) the second one uses two C2 PDEs. Finally, we compare the computational costs of direct solvers for both formulations, using the refined isogeometric analysis (rIGA) approach. [ABSTRACT FROM AUTHOR]

This paper establishes the precession model of ballistic missile warhead, and derives the formulas of micro-Doppler frequency induced by the target with precession. In order to obtain micro-Doppler feature of ballistic missile warhead with precession, micro-Doppler bandwidth estimation algorithm, which avoids velocity compensation, is presented based on high-resolution time-frequency transform. The results of computer simulations confirm the effectiveness of the proposed method even with low signal-to-noise ratio. [ABSTRACT FROM AUTHOR]

Based on multi-material ALE method, this paper conducted a computer simulation on the explosion crater in dams with different buried depths of explosive using LS-DYNA program. The results turn out that the crater size increases with the increase of buried depth of explosive at first, but closed explosion cavity rather than a visible crater is formed when the buried depth of explosive increases to some extent. The soil in the explosion cavity is taken away by the explosion products and the soil under the explosion cavity is compressed with its density increased. The research can provide some reference for the anti-explosion design of dams in the future. [ABSTRACT FROM AUTHOR]

This paper provides an analytical approach for examining model kinetic schemes for the study on the existence of chemical clock reaction behaviour. When it exists, simple analytical expressions are derived for the induction and inhibition periods. Analytical expressions for the concentration of the reactant, auto catalyst and inhibitor chemical have been formulated for all values of the parameters using Homotopy analysis method. Then, the complex inversion formula is deployed to solve the boundary value problem. In this work the numerical simulation of the problem is studied using MATLAB simulation to examine the reaction schemes of the system. A satisfactory agreement between analytical and numerical results is noted. Analytical minimum wave speed is also calculated for various values of the reaction rate constant. [ABSTRACT FROM AUTHOR]

With wireless communication's rapid expansion, the accessible spectrum is becoming increasingly congested since the spectrum is a scarce resource and cannot be divided into infinity to accommodate each application. In addition, new wireless technologies need significant bandwidth (BW). As a result, there is a need to find a solution to such problems. Cognitive radio (CR) technology is the key to the issue of inefficient use of the spectrum. Spectrum Sensing (SS) is the key step in CR, enabling it to distinguish between spectrum states (busy or idle). This research aims to design a real-time SS system that can improve the use of the spectrum. This paper assesses the performance of the Energy Detector (EDR) technique. The first detector is an energy detector with a static threshold, while the second is an energy detector with an adaptive threshold depending on the total mean of the signal received. It is concluded that the suggested adaptive threshold method gives a better probability of detection (Pd) than the static threshold in low SNR values. The computer simulations were performed using LabVIEW NXG, and the practical implementation was done using the X310 Universal Software Radio Peripheral (USRP) platform. [ABSTRACT FROM AUTHOR]

Inventory is one of the important things in an agency or individual engaged in distribution. One of the main activities in a goods distribution service company is inventory control with the aim of minimizing inventory costs. The aim of this paper is to construct a mathematical model for warehouse inventory and optimize it to get the least cost. The proposed mathematical model is the EOQ (Economic Order Quantity) model. The model used is in a probabilistic environment. The step of the method i.e., determines the components of inventory costs, namely, ordering costs, transportation costs, storage costs, and purchasing costs. Then formulate a total inventory cost model and then proceed with the optimization of the model. And the last step is to do a numerical simulation as a real test of the model created. [ABSTRACT FROM AUTHOR]

Organic Rankine cycle (ORC) is one of the solutions for recovering waste heat into useful power output. Low-grade waste heat from various sources can be converted into electricity using ORC in many different aspects. The typical ORC systems in the market often require large amount of waste heat as the waste heat sources. Although the thermal efficiency for marketed ORC is reasonable, it will not be practical in the condition of limited available energy from small-scale waste heat or low temperature heat sources. Hence, this paper presents the numerical simulation of small-scaled ORC using design model developed in MATLAB to study the thermal efficiency of various working fluids in limited working conditions. The fluid properties were obtained from CoolProp library. Result shows that R123 has the highest thermal efficiency of 7.25% with net power output of 4.09kW for this small-scaled ORC. The ranking of refrigerants as working fluids used in the designated working condition is also presented. [ABSTRACT FROM AUTHOR]

This paper investigates through soccer simulation the calculation of the probability for each team winning Malaysia Cup 2013. Our methodology used here is we predict the outcomes of individual matches and then we simulate the Malaysia Cup 2013 tournament 5000 times. As match outcomes are always a matter of uncertainty, statistical model, in particular a double Poisson model is used to predict the number of goals scored and conceded for each team. Maximum likelihood estimation is use to measure the attacking strength and defensive weakness for each team. Based on our simulation result, LionXII has a higher probability in becoming the winner, followed by Selangor, ATM, JDT and Kelantan. Meanwhile, T-Team, Negeri Sembilan and Felda United have lower probabilities to win Malaysia Cup 2013. In summary, we find that the probability for each team becominga winner is small, indicating that the level of competitive balance in Malaysia Cup 2013 is quite high. [ABSTRACT FROM AUTHOR]

In this paper, an effect of the multistage injection of several proppants on the development of a hydraulic fracture is considered. To solve the problem, the multiphase particle-cell method (MP-PIC) was used without taking into account the interaction between the particles. The numerical algorithm was built-in as a module into the Planar3D ELSA fracture simulator for a multilayer medium. [ABSTRACT FROM AUTHOR]

In the present paper, a method of local statistical regularization is studied for solving image reconstruction problems in emission tomography with Poisson data. A priori model based on the properties of the object under study is developed. A new reconstruction algorithm MAP-KL based on the Bayesian Maximum a Posteriori (MAP) approach with the a priori probability density defined by the Kullback-Leibler (KL) divergence is proposed. To study the developed local regularization method and to compare the MAP-KL algorithm with the standard maximum likelihood approach, computer simulation of SPECT liver imaging was performed. [ABSTRACT FROM AUTHOR]

A method was developed for prediction of the acoustic characteristics of resonant liner samples based on numerical simulation of physical processes in a normal incidence interferometer. Numerical simulation was performed based on direct solution of the non-stationary compressible Navier-Stokes equations in a three-dimensional formulation. The studies were carried out for full-scale multilayer samples of honeycomb acoustic liners with geometric characteristics close to those actually used in aircraft engines. The results of computations were compared with results of prediction based on semiempirical model and with results of natural experiments on normal incidence interferometer. It was revealed that the acoustic characteristics obtained by numerical simulation are in better agreement with the results of natural experiments than those determined by semiempirical model. [ABSTRACT FROM AUTHOR]

In this paper we present a numerical study of two streamwise supersonic vortices interaction. A pair of vortices was generated by two coaxial straight wings with sharp leading and trailing edges. Mach number of incoming flow was M∞ = 3. Two configurations are considered: a pair of co-rotating vortices and a pair of counter-rotating vortices. In the case of counter-rotating vortices the wings attack angle was 10 degrees. In the case of co-rotating vortices the attack angle of one of the wings was 10 degrees, the attack angle of other one was -10 degrees. Numerical data were obtained in the domain of 10 wing chords downstream from a wings axis by a computational model based on the URANS equations with SA turbulence model. Numerical simulations were performed on the hybrid supercomputing system K-60 at the Keldysh Institute of Applied Mathematics RAS using the developed software package ARES for 3D turbulent flows modeling on high performance computing systems. This work is a continuation of the series of author's works dedicated to the supersonic wingtip vortices. [ABSTRACT FROM AUTHOR]

The paper presents a practical implementation of hybrid simulation using Real Time Finite Element Method (RTFEM). Hybrid simulation is a technique for investigating dynamic material and structural properties of mechanical systems by performing numerical analysis and experiment at the same time. It applies to mechanical systems with elements too difficult or impossible to model numerically. These elements are tested experimentally, while the rest of the system is simulated numerically. Data between the experiment and numerical simulation are exchanged in real time. Authors use Finite Element Method to perform the numerical simulation. The following paper presents the general algorithm for hybrid simulation using RTFEM and possible improvements of the algorithm for computation time reduction developed by the authors. The paper focuses on practical implementation of presented methods, which involves testing of a mountain bicycle frame, where the shock absorber is tested experimentally while the rest of the frame is simulated numerically. [ABSTRACT FROM AUTHOR]

In this paper we discuss a fractional order predator-prey model with ratio-dependent functional response. The dynamical properties of this model is analyzed. Here we determine all equilibrium points of this model including their existence conditions and their stability properties. It is found that the model has two type of equilibria, namely the predator-free point and the co-existence point. If there is no co-existence equilibrium, i.e. when the coefficient of conversion from the functional response into the growth rate of predator is less than the death rate of predator, then the predator-free point is asymptotically stable. On the other hand, if the co-existence point exists then this equilibrium is conditionally stable. We also construct a nonstandard Grnwald-Letnikov (NSGL) numerical scheme for the propose model. This scheme is a combination of the Grnwald-Letnikov approximation and the nonstandard finite difference scheme. This scheme is implemented in MATLAB and used to perform some simulations. It is shown that our numerical solutions are consistent with the dynamical properties of our fractional predator-prey model. [ABSTRACT FROM AUTHOR]

The paper presents the data obtained through physical experiments of reinforced concrete destruction by electric discharges as well as the results of computer simulation of the impulse action on reinforced concrete from an expanding discharge channel. It is found that concrete starts being destroyed under the pulse electrical discharge loading at the energy of 1 kJ after 2nd or 3rd pulse. The specific energy consumption of the destruction process makes less than 0.7 kJ/cm³. [ABSTRACT FROM AUTHOR]

Numerous environmental/engineering applications relying upon the theory of diffusion phenomena into chaotic environments have recently stimulated the interest toward the numerical solution of parabolic partial differential equations (PDEs). In the present paper, we outline a formulation of the mathematical problem underlying a quite general diffusion mechanism in the natural environments, and we shortly emphasize some remarks concerning the applicability of the (straightforward) finite difference method. An illustration example is also presented. [ABSTRACT FROM AUTHOR]

With the digitalization of music, the number of collection of music increased largely and there is a need to create lists of music that filter the collection according to user preferences, thus giving rise to the Automatic Playlist Generation Problem (APGP). Previous attempts to solve this problem include the use of search and optimization algorithms. If a music database is very large, the algorithm to be used must be able to search the lists thoroughly taking into account the quality of the playlist given a set of user constraints. In this paper we perform an evolutionary meta-heuristic optimization algorithm, Differential Evolution (DE) using different combination of parameter values and select the best performing set when used to solve four standard test functions. Performance of the proposed algorithm is then compared with normal Genetic Algorithm (GA) and a hybrid GA with Tabu Search. Numerical simulations are carried out to show better results from Differential Evolution approach with the optimized parameter values. [ABSTRACT FROM AUTHOR]