Channel simulators are powerful tools that permit performance tests of the individual parts of a wireless communication system. This is relevant when new communication algorithms are tested, because it allows us to de...
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Channel simulators are powerful tools that permit performance tests of the individual parts of a wireless communication system. This is relevant when new communication algorithms are tested, because it allows us to determine if they fulfill the communications standard requirements. One of these tests consists of evaluating the system performance when a communication channel is considered. In this sense, it is possible to model the channel as an FIR filter with time-varying random coefficients. If the number of coefficients is increased, then a better approach to real scenarios can be achieved;however, in that case, the computational complexity is increased. In order to address this issue, a design methodology for computing the time-varying coefficients of the fading channel simulators using consumer-designed graphic processing units (GPUs) is proposed. With the use of GPUs and the proposed methodology, it is possible for nonspecialized users in parallel computing to accelerate their simulation developments when compared to conventional software. Implementation results show that the proposed approach allows the easy generation of communication channels while reducing the processing time. Finally, GPU-based implementation takes precedence when compared with the CPU-based implementation, due to the scattered nature of the channel.
An economic user-centric WiFi offloading algorithm is proposed to satisfy the major concerns of wireless users, who wish to have better network performance with even less network expense. Thus in this paper both syste...
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An economic user-centric WiFi offloading algorithm is proposed to satisfy the major concerns of wireless users, who wish to have better network performance with even less network expense. Thus in this paper both system throughput and network expense are considered, and the goal of the proposed offloading algorithm is to obtain an optimal offloading ratio, which can both maximize the system throughput and minimize the network expense. Firstly, a practical system model is set up on the basis of a typical scenario of heterogeneous network. In this model, the average throughput of both cellular network and WiFi network is analyzed carefully. Then an economic user-centric WiFi offloading algorithm is proposed with an evaluation function to evaluate the system, and the optimal offloading ratio can be obtained by minimizing the evaluation function. At last, numerical results represent a direct calculating process of the optimal offloading ratio. These results in return validate the efficiency of the proposed offloading algorithm as well.
Mating of components is a major production step in automated assembly lines. Many aspects in mating two parts can be reduced to a peg-in-hole problem. When the parts are fitted to each other, jamming may occur, leadin...
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Mating of components is a major production step in automated assembly lines. Many aspects in mating two parts can be reduced to a peg-in-hole problem. When the parts are fitted to each other, jamming may occur, leading to assembly failure or damage to the parts, to the robot, or to its enviroment. Therefore, an intrinsically safe environment is required for the developement and testing of new algorithms. In this paper we present a workflow for developing control algorithms by means of a Virtual Testbed: First, we create a virtual setup to test and optimize the algorithm in simulation. This setup comprises a digital twin of the used physical manipulator and an application-oriented virtual environment for its operation. Then an algorithm for peg-in-hole insertion is developed that copes successfully with peg and hole fitted to each other with small clearances. This algorithm is tested and validated using the digital twin within the simulation. After its successfully validation in a virtual testbed, the algorithm is transfered to a physical setup containing the physical KUKA LWR4 manipulator and manufactured assembly parts.
An introduction is presented in which the editor discusses various reports within the issue on topics including problem of mining big data, Resource Description Framework (RDF) graphs, and cloud particle optimization ...
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An introduction is presented in which the editor discusses various reports within the issue on topics including problem of mining big data, Resource Description Framework (RDF) graphs, and cloud particle optimization algorithm based on decomposition.
This paper combines an iterative approach based voltage control algorithm for allocating the reactive power outputs of distributed energy sources (DERs) with an Augmented Lagrangian voltage deviation optimization mode...
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ISBN:
(纸本)9781509041695
This paper combines an iterative approach based voltage control algorithm for allocating the reactive power outputs of distributed energy sources (DERs) with an Augmented Lagrangian voltage deviation optimization model that takes tap positions into consideration. The approach is applied to a modified IEEE 123 bus distribution test system with several PVs of varying output. Voltage variations due to the intermittent nature of the PVs in the distribution system are constrained by scheduling reactive power injections from the inverters. Allocating reactive power outputs of PVs and changing transformer tap positions allows the proposed approach to be used as an alternative to traditional distribution voltage control approaches. Simulation results show that the proposed method is able to keep voltage magnitudes in the normal voltage magnitude range with few tap operations.
This paper proposes the use of a variable step based improved least sum of exponentials (VS-ILSE) control algorithm for single stage three phase grid connected photovoltaic (PV) system. The VS-ILSE algorithm provides ...
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This paper proposes the use of a variable step based improved least sum of exponentials (VS-ILSE) control algorithm for single stage three phase grid connected photovoltaic (PV) system. The VS-ILSE algorithm provides a fundamental weight of active and reactive power components of load currents which are used to generate reference grid currents. This control algorithm provides the power quality improvement of distribution network likes load balancing, power factor correction. The perturb and observe (P&O) MPPT (Maximum Power Point Tracking) algorithm is used to obtain reference DC link voltage of VSC and also used to extract maximum power from the SPV array during varying environmental conditions. The proposed system is simulated in MATLAB/Simulink based environment of simpower system toolbox. The proposed algorithm is verified on a developed hardware and obtained responses are found satisfactory. The total harmonics distortions (THDs) of the grid currents and CCP (Common Coupling Point) voltages are found well according to an IEEE-519 and IEEE-929 standards.
The operational reliability of the space manipulator is closely related to the control method. However the existing control methods seldom consider the operational reliability from the system level. A method to constr...
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The operational reliability of the space manipulator is closely related to the control method. However the existing control methods seldom consider the operational reliability from the system level. A method to construct the operational reliability system control model based on particle filter for the space manipulator is presented in this paper. Firstly, the definition of operational reliability and the degree of operational reliability are given and the state space equations of the control system are established as well. Secondly, based on the particle filter algorithm, a method to estimate the distribution of the end position error and calculate the degree of operational reliability with any form of noise distribution in real time is established. Furthermore, a performance model based on quality loss theory is built and a performance function is obtained to evaluate the quality of the control process. The adjustment value of the end position of the space manipulator can be calculated by using the performance function. Finally, a large number of simulation results show that the control method proposed in this paper can improve the task success rate effectively compared to the simulation results using traditional control methods and control methods based on Bayesian estimation.
The reproducing kernel algorithm is described in order to obtain the efficient analytical-numerical solutions to nonlinear systems of two point, second-order periodic boundary value problems with finitely many singula...
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The reproducing kernel algorithm is described in order to obtain the efficient analytical-numerical solutions to nonlinear systems of two point, second-order periodic boundary value problems with finitely many singularities. The analytical-numerical solutions are obtained in the form of an infinite convergent series for appropriate periodic boundary conditions in the space W-2(3)[0, 1], whilst two smooth reproducing kernel functions are used throughout the evolution of the algorithm to obtain the required nodal values. An efficient computational algorithm is provided to guarantee the procedure and to confirm the performance of the proposed approach. The main characteristic feature of the utilized algorithm is that the global approximation can be established on the whole solution domain, in contrast with other numerical methods like onestep and multistep methods, and the convergence is uniform. Two numerical experiments are carried out to verify the mathematical results, whereas the theoretical statements for the solutions are supported by the results of numerical experiments. Our results reveal that the present algorithm is a very effective and straightforward way of formulating the analytical-numerical solutions for such nonlinear periodic singular systems.
Dense deployment of femtocells can cause serious intra-tier interference in femtocell networks. In this paper, a new cooperative interference management approach which allows the femtocell user equipment (FUE) to merg...
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Dense deployment of femtocells can cause serious intra-tier interference in femtocell networks. In this paper, a new cooperative interference management approach which allows the femtocell user equipment (FUE) to merge into cooperative groups, that is, coalitions, for the uplink transmissions in a femtocell network is proposed, so as to reduce the intra-tier interference and improve the system performance. Taking into account the power cost for cooperation, we claim that all the FUEs are impossible to merge together, and we formulate the proposed cooperative problem as a coalitional game in partition form with an externality due to the interference between the formed coalitions. To get the solution, a novel distributed coalition formation algorithm that takes advantage of the characteristics of femtocell network and allows the FUEs to interact and individually decide on which coalitions to participate in is proposed. Furthermore, we analyze the convergence and stability of the proposed algorithm. Simulations are conducted to illustrate the behavior and the performance of the proposed coalition formation algorithm among FUEs. Results show that the proposed algorithm can improve the system performance with much lower complexity than some previously proposed coalition formation algorithms.
It is difficult to well distinguish the dimensionless indexes between normal petrochemical rotating machinery equipment and those with complex faults. When the conflict of evidence is too big, it will result in uncert...
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It is difficult to well distinguish the dimensionless indexes between normal petrochemical rotating machinery equipment and those with complex faults. When the conflict of evidence is too big, it will result in uncertainty of diagnosis. This paper presents a diagnosis method for rotation machinery fault based on dimensionless indexes combined with K-nearest neighbor (KNN) algorithm. This method uses a KNN algorithm and an evidence fusion theoretical formula to process fuzzy data, incomplete data, and accurate data. This method can transfer the signals from the petrochemical rotating machinery sensors to the reliability manners using dimensionless indexes and KNN algorithm. The input information is further integrated by an evidence synthesis formula to get the final data. The type of fault will be decided based on these data. The experimental results show that the proposed method can integrate data to provide a more reliable and reasonable result, thereby reducing the decision risk.
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