Search for: cost-functions
Total 134 records
Article 2006 IIE Annual Conference and Exposition, Orlando, FL, 20 May 2006 through 24 May 2006 ; 2006 ; Haji, M ; Sharif University of Technology
This paper considers an imperfect production system in which defective items are produced in. each cycle of production. We assume that the defectives produced within each cycle will be reworked immediately after each production run is completed. We also assume some scrap is produced and detected during the rework period. Further, we assume that the number of scrapped items produced during the rework period is a random variable. For this system, using some theorem from the renewal theory, the expected total cost function per unit time is derived and the optimal batch quantity is obtained
Article 2005 IEEE Aerospace Conference, Big Sky, MT, 5 March 2005 through 12 March 2005 ; Volume 2005 , 2005 ; 1095323X (ISSN); 0780388704 (ISBN); 9780780388703 (ISBN) ; Kosari, A. R ; Jokar, S ; Sharif University of Technology
A new methodology has been proposed which offers a systematic approach to use the so called "performance index" or cost function as the basic tool to incorporate the dynamics of the aircraft in the process of trajectory planning. Moreover, by using non-dimensional parameters a better understanding of the dynamic terms are provided. © 2005 IEEE
Article 6th International Conference on Electrical Machines and Systems, ICEMS 2003, 9 November 2003 through 11 November 2003 ; Volume 2 , 2003 , Pages 619-622 ; 750626210X (ISBN); 9787506262101 (ISBN) ; Zolghadri, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2003
The flux and torque hysteresis bands are the only gains to be adjusted in direct torque control (DTC). The torque ripple and harmonic loss of motor and switching loss of inverter are greatly influenced by them. In this paper the effects of flux and torque hysteresis bands on inverter switching loss, harmonic loss and torque ripple of induction motor are investigated through a cost function. Minimizing this cost function leads to the optimum value of the hysteresis bands of torque and flux controllers. The effect of motor speed on cost function is also investigated. © 2003 International Academic Publishers/World Publishing Corporation
Article Computers and Industrial Engineering ; Volume 79 , January , 2015 , Pages 10-17 ; 03608352 (ISSN) ; Haji, A ; Haji, R ; Sharif University of Technology
Elsevier Ltd 2015
Recently, for zero ordering cost a new ordering policy named (1, T), in which the time interval between two consecutive orders and the value of the order size are both constant, have been developed for nonperishable products. In this paper, the (1, T) policy is developed for perishable products. Using an analogy among this inventory model, a queueing model with impatient customers, and a finite dam model, the long-run average total cost function of the inventory system is derived. It is observed that the total cost rate is independent from the lead time as is for nonperishable products. Since analyzing the convexity of the model is extremely complicated, a proposition is proved to define a...
Article Industrial and Engineering Chemistry Research ; Volume 49, Issue 13 , June , 2010 , Pages 6135-6143 ; 08885885 (ISSN) ; Shahrokhi, M ; Bozorgmehri, R ; Sharif University of Technology
In this work, steady state and dynamic performances of quaternary distillation column sequences designed based on steady state and dynamic cost functions have been investigated. To quantify the dynamic performance, product losses due to disturbances have been considered in the objective function. In addition, variations of operating costs such as utilities have been considered in the objective function. To separate a quaternary mixture into four products, 22 configurations have been used. It has been observed that the feed composition, disturbance frequency and magnitude affect the dynamic behavior strongly. To decrease the optimization computational load, a scheme that provides a suboptimal...
Article IET Control Theory and Applications ; Volume 4, Issue 2 , 2010 , Pages 228-243 ; 17518644 (ISSN) ; Ramezani, M. H ; Sharif University of Technology
In this paper, a new interaction prediction approach for hierarchical control of non-linear large-scale systems is presented. The proposed approach uses a new gradient-type coordination scheme which is robust with respect to the parameters' variation, and also has a good convergence rate. In classical coordination strategies, which can be divided into the gradient-type and substitution-type approaches, it is not possible to improve the robustness and the convergence rate at the same time, since by increasing one the other decreases. The proposed approach has the main advantages of the gradient-type algorithms in being independent of the parameter's variation and also the initial guess of the...
Article IEEE Signal Processing Letters ; Volume 23, Issue 2 , 2016 , Pages 187-191 ; 10709908 (ISSN) ; Korki, M ; Marvasti, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
This letter proposes a dictionary learning algorithm for blind one bit compressed sensing. In the blind one bit compressed sensing framework, the original signal to be reconstructed from one bit linear random measurements is sparse in an unknown domain. In this context, the multiplication of measurement matrix A and sparse domain matrix φ, i.e., D = Aφ, should be learned. Hence, we use dictionary learning to train this matrix. Towards that end, an appropriate continuous convex cost function is suggested for one bit compressed sensing and a simple steepest-descent method is exploited to learn the rows of the matrix D. Experimental results show the effectiveness of the proposed algorithm...
Article 2009 International Conference on Computers and Industrial Engineering, 6 July 2009 through 9 July 2009 ; 2009 , Pages 857-862 ; 9781424441365 (ISBN) ; Haji, R ; Haji, A ; Sharif University of Technology
This paper attempts to develop the optimal solution for an inventoryproblem consisting of a single machine which produces items some of which may bedefective. We assume that no shortages are allowed and all defective items areto be reworked. Setup cost for rework and waiting time of defectives areconsidered. We consider two different policies where in the first policy in eachcycle after the regular production the machine is setup for the rework ofdefectives of the same cycle. In the second policy several cycles constitute aperiod. All the defectives produced in the period are reworked in the last cycleof that period. At the end of the rework cycle the whole process starts allover again. One...
One-for-one period policy in a two-echelon inventory system with commoncycle and poisson demand rate for retailers, Article 2009 International Conference on Computers and Industrial Engineering, CIE 2009 ; 2009 , Pages 831-834 ; 9781424441365 (ISBN) ; Tayebi, H ; Haji, B ; Sharif University of Technology
This paper deals with a two-echelon inventory system consisting of onesupplier and N retailers. Each retailer faces an independent Poisson demand withthe same rate and applies a new ordering policy called one-for-one- periodordering policy for its inventory control. In this ordering policy the ordersize is equal to one and the time interval between any two consecutive ordersforms a common fixed cycle. Thus, the supplier faces a deterministic demand andadopts a deterministic inventory policy. At each cycle he orders a batch of sizeN to his own supplier. Upon receipt of each batch he sends 1 unit of theproduct to each retailer with a transportation cost. In this paper, for theabove system we...
One-for-one period policy in a two-echelon inventory system with poisson demand and constraint on total lost sales, Article 2009 IEEE/INFORMS International Conference on Service Operations, Logistics and Informatics, SOLI 2009, Chicago, IL, 22 July 2009 through 24 July 2009 ; 2009 , Pages 74-77 ; 9781424435418 (ISBN) ; Haji, B ; Sharif University of Technology
In this paper we consider a two- echelon inventory system consisting of one supplier and a number of retailers with independent Poisson demand. Unsatisfied demands in retailers are lost and it is assumed that there is a constraint on total lost sales for the system. Each retailer applies a new ordering policy called one-fer-one-peried ordering policy for its inventory control. In this ordering policy the order size is equal to one and the time interval between any two consecutive orders is fixed. Thus, the supplier faces a uniform and deterministic demand originated from each retailer and applies one for one ordering policy in response to orders received from all retailers. For this system...
Article 11th Power Electronics, Drive Systems, and Technologies Conference, PEDSTC 2020, 4 February 2020 through 6 February 2020 ; 2020 ; Zolghadri, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2020
Nowadays, Programmable Electronic AC Load (PEAL) is widely used to test various devices such as solar inverters, UPSs, filters, generators, and generally test all AC power and measuring devices. In this paper, Model Predictive Current Control (MPCC) is used for control of a programmable AC load. In each period, switching state that minimizes the cost function is selected and applied to the converter. Cost function is the square of the current components error. The effect of the horizon of prediction on the quality of the load current is investigated. To decrease the calculations burden, a limited search pool is used. Simulation results confirm that using two steps prediction horizon with...
Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 48, Issue 1 , 2012 , Pages 44-63 ; 00189251 (ISSN) ; Kosari, A. R ; Sharif University of Technology
In this work we present a systematic approach to incorporating the dynamic capabilities of an aircraft via suitable cost functions while planning for terrain following-terrain avoidance trajectories. We further show that use of nondimensional parameters related to the dynamics of an aircraft within the cost function provides a better understanding of how they could affect the resulting trajectories. Different case studies for arbitrary three-dimensional flights show that the current approach provides more realistic trajectories and so helps alleviate the design process of relevant controllers as well as tracking systems over the desired terrain. We further introduce two new parameters of...
A novel multi-agent evolutionary programming algorithm for economic dispatch problems with non-smooth cost functions, Article 2007 IEEE Power Engineering Society General Meeting, PES, Tampa, FL, 24 June 2007 through 28 June 2007 ; July , 2007 ; 1424412986 (ISBN); 9781424412983 (ISBN) ; Hosseini, S. H ; Sharif University of Technology
This paper presents a new approach to economic dispatch (ED) problem with non-continuous and non-smooth cost functions using a hybrid evolutionary programming (EP) algorithm. In the proposed method the concept of multi-agent (MA) systems and EP are integrated together to form a new multi-agent evolutionary programming (MAEP) approach. In MAEP, an agent represents a candidate solution to the optimization problem in hand, and all agents live together in a global environment. Each agent senses its local environment, competes with its neighbors, and also learns by using its own knowledge. MAEP uses these agent-agent interactions and the evolutionary mechanism of EP to obtain the optimal...
Control of different FEM based musculoskeletal models of human lumbar spine under different loading conditions using optimization method, Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) ; Parnianpour, M ; Shirazi Adl, A ; Sharif University of Technology
American Society of Mechanical Engineers 2006
In this study the effects of using different musculoskeletal models on load-displacement behavior of FE models of the human lumbar spine under external loads and moments have been analyzed in terms of equilibrium and clinical stability. A simplified and a complex architecture of muscles have been integrated to FE based models of lumbar spine and were loaded to simulate the load carrying behavior of human lumbar spine in flexion, extension and lateral bending. The displacement values as well as muscle forces have been computed and compared in both cases using optimization methods with different cost functions. The models showed similar kinematics in pure flexion but the simplified model...
Optimal circular 3-arced with constant speed coordinated maneuvers for planar multi aircraft conflict resolution, Article 23rd Digital Avionics Systems Conference - Proceedings: Avionics System Transitioning to the Next Generation, Salt Lake City, UT, 24 October 2004 through 28 October 2004 ; Volume 1 , 2004 , Pages 3.E.4-1-3.E.4-10 ; Parastari, J ; Sharif University of Technology
In this paper, the problem of designing optimal conflict-free maneuvers for multiple aircraft encounters is studied. The proposed maneuvers are based on changes of heading, speed and maneuvering time. The optimality of maneuvers among the conflict-free constraint is based on minimization of a certain cost function based on kinetic energy of either aircraft involved. Some suitable priority weight factors are incorporated into the cost function so that optimal resolution maneuvers are such that aircraft with lower priorities assume more responsibility in resolving the conflicts. As for considering aircraft turning dynamics, the circular 3-arced path with constant speed are proposed for each...
Hysteresis band determination of direct torque controlled induction motor drives with torque ripple and motor-inverter loss considerations, Article 2003 IEEE 34th Annual Power Electronics Specialists Conference, Acapulco, NM, 15 June 2003 through 19 June 2003 ; Volume 3 , 2003 , Pages 1107-1111 ; 02759306 (ISSN) ; Zolghadri, M. R ; Emadi, A ; Sharif University of Technology
The flux and torque hysteresis bands are the only gains to be adjusted in direct torque control (DTC). The torque ripple and harmonic loss of motor and switching loss of inverter greatly Influence them. Hence, these variables must be observed in the control process to maximize performance of the system. In this paper, the effects of flux and torque hysteresis bands on inverter switching loss, harmonic loss, and torque ripple of induction motor are investigated. In order to find their optimum values, a cost function consisting motor harmonic losses, torque ripples, and inverter switching losses is defined. Minimizing this cost function leads to the optimum value of the hysteresis bands of...
Article IEEE International Symposium on Industrial Electronics, ISIE 2003, 9 June 2003 through 11 June 2003 ; Volume II , 2003 , Pages 1049-1052 ; 0780379128 (ISBN) ; Zolghadri, M. R ; Homaifar, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2003
The torque ripple and harmonic loss of motor and switching loss of inverter are greatly influenced by sampling time in the direct torque control method. Hence these variables must be observed in the control process to maximize performance of the system. In this paper the effects of sampling time on inverter switching loss, harmonic loss and torque ripple of induction motor are investigated. To find their optimum values a cost function consisting of motor harmonic losses, torque ripples and inverter switching losses are defined. Minimizing this cost function leads to the optimum value of the sampling time. © 2003 IEEE
Article ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings ; 2013 , Pages 5855-5859 ; 15206149 (ISSN) ; 9781479903566 (ISBN) ; Babaie Zadeh, M ; Jutten, C ; IEE Signal Processing Society ; Sharif University of Technology
During the last decade, there has been a growing interest toward the problem of sparse decomposition. A very important task in this field is dictionary learning, which is designing a suitable dictionary that can sparsely represent a group of training signals. In most dictionary learning algorithms, the cost function to determine the the optimum dictionary is the ℓ0 norm of the matrix of decomposition coefficients of the training signals. However, we believe that this cost function fails to fully express the goal of dictionary learning, because it only sparsifies the whole set of coefficients for all training signals, rather than the coefficients for each training signal individually. Thus,...
Determination of the economical policy of a three-echelon inventory system with (R, Q) ordering policy and information sharing, Article International Journal of Advanced Manufacturing Technology ; Volume 55, Issue 5-8 , 2011 , Pages 831-841 ; 02683768 (ISSN) ; Sajadifar, S. M ; Haji, R ; Sharif University of Technology
In this work, we consider a three-echelon serial inventory system with two warehouses (suppliers) and one retailer with information exchange. The retailer applies continuous review (R, Q) policy. The warehouses have online information on the inventory position and demand activities of the retailer. We present a new ordering policy to share information among inventory echelons. The warehouse I and II start with m 1 and m 2 initial batches of the same order size of the retailer, respectively. The warehouse I places an order to an outside source immediately after the retailer's inventory position reaches an amount equal to the retailer's order point plus a fixed value s 1, and the warehouse II...
Article 2000 10th European Signal Processing Conference, EUSIPCO 2000, 4 September 2000 through 8 September 2000 ; Volume 2015-March, Issue March , 2015 ; 22195491 (ISSN) ; Champagne, B ; Valaee, S ; Sharif University of Technology
European Signal Processing Conference, EUSIPCO 2015
In this paper, we present a method for estimating the signal sources steering vector using an arbitrary planar array with omnidirectional elements. The proposed method improves the initial estimation of the signal steering vector in two steps. In the first step of this algorithm we minimize of the distance between the steering vector and the signal subspace. The second step improves the estimation of the first step using a defined cost function which is based on a structural criterion for signal steering vector. Simulation results show the capability of the proposed signal steering vector estimate improvement