查看更多>>摘要：This work deals with the inverse problem of reconstructing the thermal conductivity coefficient of the (2+1) D heat equation from over-posed data at the boundaries. The proposed solution uses a variational approach for identifying the coefficient. The inverse problem is reformulated as a higher-order elliptic boundary-value problem for minimization of a quadratic functional of the original equation. The resulting system consists of a well-posed fourth-order boundary-value problem for the temperature and an explicit equation for the unknown thermal conductivity coefficient. The existence and uniqueness of the resulting higher-order boundary-value problem are investigated. The unique solvability of the inverse coefficient problem is proven. The numerical algorithm is validated and applied to problems of reconstructing continuous nonlinear coefficient and discontinuous coefficients. Accurate and stable numerical solutions are obtained.
PEDRO FOLHENTORUI CARNEIRO DE BARROSMANUEL BRAZ-CESAR
13页
查看更多>>摘要：Structural pounding has been found to have a significant influence on the dynamic behavior of building structures under earthquake excitations. This phenomenon is more probable when the buildings have insufficient separation distance and substantial different dynamic properties. In large cities, it is more common for adjacent buildings to have unequal heights, leading to different demands in the structures' stories under earthquake-induced pounding. Hence, in this study five different buildings' configurations with equal or unequal heights and subjected to different ground motions are considered, to study how pounding influences the dynamic behavior of the involved structures. It was found, among other results, that the peak responses tend to suffer amplifications at the stories of the taller building above the height of the shorter building.
FAWZAN ISMAIL SIDKYDOAA SHOKRY MOHAMEDAMINA AHMED AWAD
8页
查看更多>>摘要：In this paper, we introduce new subclasses of analytic and p-valent functions related to starlike, convex, close-to-convex, and quasi-convex functions by using a p-valent analog of the Tremblay fractional derivative operator. Inclusion relationships for these subclasses are established.
查看更多>>摘要：This paper presents an efficient covid-19 optimization algorithm to find the optimal values of the PD/PID cascaded controller. The purpose of the control algorithm is to force the link shaft to follow the desired reference position with good accuracy all time. This objective should be achieved for different position/time tracks regardless of load disturbance and parameter variations. This work, simulating how the covid-19 spreads and infects to optimize the parameters of the PD/PID control. The initial values of PD/PID controller parameters consider the zero patient, which infects new patients (other values of PD/PID controller parameters). The optimization model simulates as accurately as possible the covid-19 activity. The covid-19 has two major advantages compared to other similar strategies. First, the covid-19 parameters are already adjusted according to disease statistics to prevent designers from initializing them with arbitrary values. Second, the approach has the ability to finish after several iterations where the infected population initially grows at an exponential rate. However, after some iterations. The proposed covid-19 was investigated with well-known optimization techniques such as the genetic algorithm (GA) and Harmony Search (HS) optimization. A multi-objective function is used to allow the designer to select the desired rise time, the desired settling time, the desired overshoot, and the desired steady-state error. Several tests have been performed to investigate the obtained proper values of PD/PID controller parameters. In the first test, a step position reference had been applied. In the second test, the continuous change in position reference had been subjected to the robot arm. The results provide that the covid-19 based PD/PID controller has the best performance among other techniques. In addition, the covid-19 based PID controller can track accurately the position command compared to other techniques.
查看更多>>摘要：The main aim of this paper is to propose new methods in constructing generators for Archimedean copulas (AC). After reviewing some construction methods of AC generators, three general methods are proposed to construct new generators. These new methods are based on any convex and decreasing functions on and for these forms several examples are provided.
查看更多>>摘要：Proposed activity presents next stage of the study of the problem of the plane-parallel motion of a rigid body interacting with a resistant medium through the frontal plane part of its external surface. Under constructing of the force acting of medium, we use the information on the properties of medium streamline fl w around in quasistationarity conditions (for instance, on the homogeneous circular cylinder input into the water). The medium motion is not studied, and we consider such problem in which the characteristic time of the body motion with respect to its center of masses is comparable with the characteristic time of motion of the center of masses itself.
查看更多>>摘要：A high frequency rectifier is the core of a RF energy harvesting system. It should offer a very good efficiency at low input power levels and to obtain that compensation of threshold voltage is a very important aspect. A threshold compensation scheme for MOSFETS for RF rectifier applicable in RF energy harvesting system is presented in this paper. The switching of the MOSFET is improved with overall enhancement of output rise time of the system. The design emphasis is to have a simplified circuit without the requirement of any external source so as to achieve self-sustainability in the true sense. The rectifier circuit is derived from the basic Dickson charge pump model and is evaluated using 45nm CMOS process. The design has utilized Metal Oxide Semiconductor Field Effect Transistor instead of basic diodes which ensures low power along with fabrication feasibility. The maximum measured PCE of the design is obtained to be 33% at 4dBm input power level at 500Mhz frequency with 1 Kilo Ohm load resistance. The output transient response rise time has been measured to be 85ns at 500MHz and 50.10ns at 1Ghz.
Guia Sana SaharKazar OkbaLaouid AbdelkaderYagoub Mohammed Amine...
11页
查看更多>>摘要：The multi-depot vehicle routing problem is a variant of the vehicle routing problem that tries to minimize the total cost of providing the service from several depots to satisfy several client demands. This paper presents a multi-ant colony system to solve the multi-depot vehicle routing problem using a reactive agent-based approach. This approach is designed to effectively solve the problem, in which each reactive agent is inspired by modeling the behavior of the ant. We define two types of reactive agents whose behavior differs in the use of two kinds of pheromone trail. In order to refer to the two phases of the execution process, i.e., the assignment phase and the routing phase, every reactive agent cooperates with others to provide a scalable solution for the overall problem. The solution of the multi-depot vehicle routing problem is beneficial and helpful for many real applications. The performance evaluation of the proposed approach is done using instances from the literature, and the results obtained demonstrate good performance when compared with other approaches.
查看更多>>摘要：Mobile devices, such as smartphones, tablets, laptops, and music players, have been increasingly popular. There is a strong demand for charging stations for these devices, especially in public places, such as bus stops, parks, beaches, schools, hospitals, and playgrounds. This project designs a convenient charging station for the mobile devices. It is renewable and supportive for diverse charging needs. The system key design parameters are: 200-W solar panel, 12-V 900-Wh deep-cycle lead acid battery, 300-W 120-VAC pure sine-wave inverter, 8 outlets (2 wireless, 4 DC USB and 2 AC). It aims to supply an average load of 175Wh. A prototype of the station is built and tested. The testing results show that the station works properly. The control system switches the outlets on and off accurately based on the battery available energy. On a sunny day, with the solar panel and the battery operational, the system can support a full load of 150Wh until the sun is gone. When operating without the solar panel using the fully-charged battery, the system can last at least 1.5 hours. The station can serve as a convenient power source. It helps promote the use of solar energy that is beneficial to the environment.
查看更多>>摘要：This article studies the problem of designing robust control laws to achieve multiple performance objectives for linear uncertain systems. Specifically, in this study we have selected one of the control objectives to be a closed-loop pole placement in specific regions of the left-half complex plane. As such, a guaranteed cost-based multi-objective control approach is proposed and compared with the H_2/H_∞ control by means of an application example.
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