Sharif Digital Repository

In this thesis, we study optimal scheduling in a multi-hop wirelessly-powered network. We propose an online control policy for energy transfer from the energy access point to the wireless nodes and for data transfer among the nodes. With our proposed control policy, all data queues of the nodes are stable, while the average energy consumption of the network is shown to be within a bounded gap of the minimum energy required for stabilizing the network. Our proposed policy is designed using a quadratic Lyapunov function to capture the limitations on the energy consumption of the nodes imposed by their bachery levels. We show that under the proposed control policy, the bachlog level in the data... 

This research deals with a realistic cyclic three-stage supply chin consisting of one supplier, one manufacturer and one or more retailers, in FMCG environment. Orders from retailers are supposed to iterate over cycles and parallel machines are available to process perishable jobs with given release dates, due dates and deadlines. To start process of he jobs, perishable raw material, supplied by an external supplier, is required. Jobs are subject to post-production shelf life limitation and must be delivered to retailers during the corresponding time window bounded by due dates and deadlines. Both early and tardy jobs are penalized by partial weighted earliness/tardiness functions and the... 

In the present work, the integration of production scheduling and process control in a multi-product CSTR reactor is addressed. In order to reduce the complexity of solving this integrated problem, in the scheduling layer, a reduced closed-loop model, named scale bridging model, based on neural network concept is used. In the control layer, a neural network-based controller is used to achieve control objectives such as tracking, stability and robustness against model uncertainty. In addition, the designed closed loop system is used to obtain offline setpoint-output data set in order to train neural network based scale bridging model. In a comparative study, both simultaneous and sequential... 

In the research, the order acceptance and scheduling problem is integrated with pricing in order to maximize the net profit. Two mixed linear integer programming models have been proposed for the problem. A two level tabu search algorithm is proposed to solve the model. The suitable structure is determined for the algorithm based on numerical experiments. Based on experimental design results, the hybrid of random initial solutions and swap move in neighborhoods determination is the best structure for the algorithm. Numerical analysis shows the reasonable performance of proposed algorithm  

CIM includes major components with different performances, although in last decades any researchers starting a way to high level of integration in these functions. Process planning and scheduling are two tasks of manufacturing that searches have not paid attention to them. In the other word there is a good environment for integration studies but researchers didn’t find best approach for integrating these two tasks.The proposed approach can quickly integrate these two functions and be implemented in a company without working process planning and scheduling departments separately. This methodology consists of four main modules that introduced in detail in this study. They are Integrated... 

One of the fundamental constraints that should have been in mind in flight scheduling is aircraft maintenance scheduling. Based on the accepted rules, regulations and flight safety, in a given period of time or after definite number of flight hours each aircraft should be sent to maintenance site. This influences the flight schedule. This research provides a comprehensive model for the flight scheduling. Given the flight schedule, number of the flights and aircrafts, maintenance center's capacity and other parameters such as each check's time, allowable flight days and allowable flight hours this model could determine each season's flight schedule and solve the aircraft routing problem.... 

Nowadays a lot of people from all around the world travel by inter-city trains and this phenomenon is the direct result of the fact that this travel mode is more affordable and relatively comfortable in comparison to other modes. Furthermore, recent developments such as the emergence of high-speed rail lines have made rail transportation able to compete with other means of transportation such as airplanes. Therefore, the practice of maximizing train networks’ resilience against probable disruptions has drawn significant attention to itself. This study introduces a novel methodology in which train network resilience can be maximized through three stages. In the first stage, the critical nodes... 

This study, with integrated approach to the POM problem, has developed a linear mutual MILP model with the hybrid MTS / MTO operational approach on the OAS problem in industry 4.0 environment for the Shahin Plastic Manufacturing Company. This enabled an integrated PM with the production in the scheduling model. The model objective function has minimized costs and maximized the company profits. It also maximized customer satisfaction by minimizing the tardiness and earliness time in producing orders. To implement this model in the factory decision-making system, measures and modifications have been made to the MIS structure of the corporate departments. Measures include the creation of cloud... 

This research intends to investigate the multi-skilled project scheduling problems (MSPSP) considering staffs’ dynamic efficiency. In doing so, a mixed-integer nonlinear programming (MINLP) model is proposed, considering the influence of personnel learning and forgetting on activities duration. The more the staff spends time on their various skills, the more learned and efficient they will be on that skill (according to personal learning curves) so that they can complete new tasks less costly and more quickly. Most project-based organizations want to maximize value by finishing the projects efficiently and developing their staff’s competence through projects. Inherently, any... 

The applications that consist ofprecedence-constrained parallel taskshave used in business activities and scientific projects and the energy consumption of these application has become a major concern in datacenters. At the software level, energy-aware task scheduling algorithmsare an effective technique for energy reduction and optimizing performance in data centers. The related works in this areahave traditionally ignore the utilization value of physical machines (PMs) and while the main reason of the energy inefficiency in datacenters is low average utilization of the PMs.In this paper, we propose a new energy-aware scheduling (EASy) algorithm forprecedence-constrained parallel taskswith... 

The constrained nonlinear systems with large operating regions have attracted great attention due to their correspondence with the most practical systems. There are several tools such as gain scheduling and Nonlinear Model Predictive Control (NMPC) to control them. Gain scheduling, with ability to provide stability guarantees between the estimated stability regions overlapping each other and to cover a large space of the allowable operating range of the system, is an attractive practical approach to control the systems with large operating regions. But this strategy do not account for constraints explicitly by online optimization. On the contrary, NMPC handles constraints on the manipulated... 

One of the model based control strategies that has been proposed in recent years for the control of process systems is the one based on the economic models, in which objective functions with an economic basis are used along with the equations and constraints to perform control calculations. In this work, the control of a multiproduct continuous stirred reactors is discussed, in which, it is possible to produce different products based on changes in the market demand, the price of the products or the primary raw materials according to a specific schedule. One of the recently used methods is the economic predictive control method based on the Lyapunov function. In this method a quadratic... 

This research investigates permutation flow shop scheduling problems with sequence-dependent setup times with minimizing the number of tardy jobs as criterion (Fm|prmu, Sijk|ΣUj). A mixed integer linear programming model has been developed for the research problem. As the problem is shown to be NP-hard, several meta-heuristic algorithms based on tabu search (TS) and imperialist competitive algorithm are developed to heuristically solve the problem. In order to find the best meta-heuristic algorithm, random test problems, ranging in size from small, medium, to large are created and solved by the meta-heuristic algorithms. Then, a detailed statistical experiment, based on split-plot design is... 

In this research, a scheduling problem, minimizing the sum of weighted earliness/tardiness in a flow shop sequence-dependent group scheduling (FSDGS) problem, is investigated. In this problem, every job has a distinct due date, early penalty rate, and tardy penalty rate. This problem is typically classified in the literature as F_m | fmls,S_plk,prmu | ∑(w_j^1 E_j+ w_j^2 T_j). A mixed integer linear programming model is developed for the proposed research problem. As the problem is proved to be strongly NP-hard, only small-size problems can be solved with the mathematical model. Thus, a metaheuristic algorithm based on the Particles Swarm Optimization (PSO) algorithm is developed to solve... 

This research considers the permutation flowshop scheduling problem with sequence‐dependent set‐up times .In this model, every job has a distinct due date and a tardy penalty rate. A mathematical model is developed for the proposed problem. As it has been proved to be strongly NP‐hard, only small‐size problems can be solved with the mathematical approaches. Thus, a meta heuristic algorithm based on the Particles Swarm Optimization (PSO) algorithm is developed to solve the real size problems. Particle swarm optimization (PSO) has been developing rapidly and has been applied, as it is easily understood and realized. Since the PSO algorithm has been introduced for the continuous solution space,... 

Piping process is the most important part of industries projects which pay attention to construction and installation of industrial pipelines and its facilities. In the meantime, due to increasing demand of industrial units to construction and development projects, planing and scheduling the piping is necessary. We review and discuss various aspects of the piping process, optimization process and the related scheduling literature that is called Flexible Job Shop Scheduling Problem. Then, to solve the problem, considering the real world assumptions, a mathematical model, is developed and a heuristic algorithm is introduced. Also, in order to determine an appropriate bound for the optimal... 

Shrinking the dimensions of transistors in recent fabrication technologies has led to an increase in the aging rate of chips, as the most important challenge in reliability of new processors. Bias Temperature Instability (BTI) and Hot Carrier Injection (HCI) are amongst the most important adverse effect of transistor shrinkage. These two effects decrease the switching speed of transistors by increasing its threshold voltage over time. Threshold voltage shift causes timing violation in combinational parts of circuit and decreases the robustness of sequential parts against soft errors. Between different units of a processor, Arithmetic and Logic Unit (ALU) is one of the most susceptible units... 

As technology shrinks, the static power consumption is getting worse. Moreover, considering high usage of General-Purpose Graphics Processing Units (GPGPU), reducing the static power of GPGPUs is becoming an important issue. Execution units in GPGPUs are one of the most power hungry units that play an essential role in total power consumption of GPGPUs. On the other hand power gating is a promising method to reduce static power consumption. In this project, we propose a novel method to implement power-gating method for execution units with the negligible performance and power overheads. We utilize out of order execution in intra warp to keep the power-gated resources in off state more than... 

Recently, the tradeoff between low energy consumption and high fault-tolerance has attracted a lot of attention as a key issue in the design of real-time embedded systems. Dynamic Voltage Scaling (DVS) is known as one of the most effective low energy techniques for real-time systems. Control-theoretic DVS techniques, which have been exploited recently for DVS-enabled systems, are able to adapt well to dynamic workload. In this thesis, we have combined the above two important issues i.e., the control-theoretic DVS and fault-tolerance, and investigated reducing the energy consumption of fault-tolerant hard real-time systems using feedback control theory. Our proposed feedback-based DVS method... 

This research considers coordination of pricing and scheduling decisions in a make-to-order environment. We consider a two machine flowshop environment. The objective is to maximize the total net profit, i.e. revenue minus scheduling cost resulting from pricing and scheduling decisions. Prices of orders are set by the manufacturer and demand is a non-increasing function of price. Two mixed integer linear programming models have been developed for the research problem. As the problem is shown to be NP-Hard, a Metaheuristic algorithm is developed which is combination of two tabu search sub algorithms, one for pricing and the other for scheduling. And to evaluate performance, results from...