Sharif Digital Repository

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... 

The efficient scheduling of independent and sequential tasks on distributed and heterogeneous computing resources within grid computing environments is an NP-complete problem. Therefore, using heuristic approaches to solve the scheduling problem is a very common and also acceptable method in these environments. In this thesis, a new task scheduling algorithm based on bee colony optimization approach is proposed. The algorithm uses artificial bees to appropriately schedule the submitted tasks to the grid resources. Applying the proposed algorithm to the grid computing environments, the maximum delay and finish times of the tasks are reduced.Furthermore, the total makespan of the environment... 

In recent years peer-to-peer video streaming systems have become the major alternative for traditional client-server models, and several P2P streaming applications have attracted a large number of users on the Internet. In a mesh based P2P streaming architecture a video stream is portioned into video blocks and each peer pulls these video blocks from its neighbors. Since the uplink bandwidth of each peer is its main constraint in transmission video blocks, efficient block scheduling can play an important role in improving the perceived video quality by peers. Moreover, the granularity of video blocks can have a significant impact on the performance of the system. In this thesis, we propose... 

Recent advances in WSN have led to next generation of it for multimedia transmission which is WMSN. WMSN has several applications like environmental monitoring, advance health care delivery and etc. However, providing QoS requirements of transmitting video data like delay, bandwidth and packet loss with minimum distortion at perceived video quality over WMSN with resource constraints is a challenging problem. Using multipath routing protocol for video communication can increase bandwidth and decrease delay over WMSN. Moreover, all video packets have not the same effect on video distortion. We propose a scheduling mechanism which classifies packets according to their types and contents and... 

Worldwide interoperability for Microwave Access (WiMAX) is one of the most dominant cell-based broadband wireless metropolitan access technologies. Packet scheduling algorithm specifies the packet transmission order. In WiMAX standard, packet scheduling algorithm is not defined and its efficient design is left for developers and researchers. The existing researches in the scope of uplink packet scheduling, which is the most challenging packet scheduling scheme, consider only one cell. However the uplink available resources might not be enough when there are many packets that should be scheduled. To solve this problem, we propose an algorithm that uses the load balancing mechanisms that are... 

In this project we have worked on the new architecture of the auction based resource scheduling, from the bidders point of view. The performance of different bidding strategies for the resources which participate in reverse auction system has been investigated; our main parameter for evaluating different bidding strategies is the amount of the profit gained by resources which follow such strategies. The main historical bidding strategies are created based on two famous predictors ES and AUTO-REGRESSION. In addition a game theory approach has been proposed. We have shown that our bidding algorithm (based on the sequential game model) reaches to an equilibrium point if all the bidders follow... 

Queuing algorithms are used in packet forwarding elements such as routers or switches and the goal is to minimize transmission delays as well as to help manage network congestions. On the other hand, over 90 to 95% of the packets in the Internet use TCP and correspond to the transfer of digital documents of one form or another (Web pages, data files, MP3 tracks etc.) ; this kind of traffic is called elastic. In this thesis, we present a new Start-time Fair Queuing (SFQ) algorithm called Weighted Start-time Fair Queuing (WSFQ) which is more efficient and achieves better fairness than SFQ in the presence of small and huge elastic traffic flows. WSFQ scheduler, like SFQ uses a start time... 

In summary, this thesis presents a new mathematical model for Home Health Care (HHC) services during the Corona era, which aims to increase the efficiency and quality of services provided by these organizations while ensuring compliance with quarantine protocols. The model is an extension of the VRPPDTW formulation and considers relevant features such as patient classification, caregiver classification, work and break regulations, workload balancing, and multi-depot capabilities. The optimization can be performed with two separate objective functions, one to minimize traveling and idle costs and the other to minimize the total working time of caregivers. The contradictions between two... 

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 study deals with the heuristic solution of flexible flow shop scheduling problems with unrelated parallel machines. No preemption of jobs is allowed. As an objective function, this paper considers the minimization of total tardiness. As a first step to propose solution, two different mixed integer mathematical models are developed which tackle the problem at hand. The problem is NP-hard and thus the developed mathematical program can only solve problem instances for small sizes in a reasonable amount of time. The next step is to build heuristics which can provide feasible solutions in polynomial time for larger problem instances. Then in the study develops a constructive heuristic for... 

Multi core processors are becoming mainstream in the computation area, wide application of multi core processors in Engineering, Industrial purposes and scientific applications made them popular among users and Manufacturers, cloud computing is a very well known Concept which technically is a Multicore processing environment, most of Businesses, enterprises and engineering works nowadays are getting done by the help of cloud services, hence, to get the best of these multi core cloud computing systems, scheduling of the tasks on the cores and virtual machines(VMs) is necessary, which is the answer to two questions: each task must be assigned to which core(VM)? And What is the order of... 

Managing industries into the 21st century is a challenging task, because of increasing global competition, fast technological change, consumer’s perceptions towards total quality, reliability, health and safety, environmental considerations and changes in management structure.To overcome these difficulties, maintenance planning is a must such as condition monitoring (CM) technologies.Khouzestan Steel Company as the second largest Steel manufacturer in Iran, using some CM techniques & tools - like VCM, OCM, TCM and … - to maintain its continuous improvement.To assess what KSC has done, we focus on cost-benefit (CB) and availability; BY defining three phases: 1) Data Gathering, 2) Calculation... 

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... 

In recent years, various studies have been conducted focusing on the optimization and scheduling of energy hubs (EH). EH optimization is important because it tries to create synergy in the energy supply system by considering the relationships between energy carriers. For this purpose, various algorithms such as analytical methods (linear programming) and evolutionary and heuristic algorithms have been used. Also, recently, various studies have addressed the applications of reinforcement learning for energy hub management. In this study, a hybrid model for energy hub management has been developed by combining classical linear models (Known as white-box models) and reinforcement learning... 

Airline scheduling is a dynamic process in nature such that it changes not only during one year period but also in smaller intervals due to the economic, political, religious, and social factors. Basically, airlines schedule planners through using mathematical models decide which flights are to be served in what periods of time and at what costs. This has to be done considering a set of constraints of different nature, from airspace and airport congestion up to climatic conditions or even crews working conditions. Such a complex problem requires different methods for an efficient solution. In this study by using network optimization method and applying different operational constraints on... 

As an extension of known project scheduling problems which consider only time-independent costs, this problem includes both time- independent procurement costs and time-dependent renting costs for the resources. Consequently, in addition to projects where all resources are bought, we can deal with projects where resources are rented.
A resource Renting problem is a project-scheduling problem in which the availability levels of the rented resources are considered decision variables and the goal is to find a schedule and resource renting such that some objective function optimizes. In this thesis, we consider a resource renting problem in which the goal is to maximize the net present... 

With the increasing development of Internet of Things (IoT) devices, issues such as establishing effective communication, optimizing energy consumption, ensuring reliability and improving the quality of services provided by these devices become more and more complex and critical challenges. With the introduction of fog computing model by Cisco in 2012, some of these challenges were successfully managed. Fog computing is a distributed computing paradigm that acts as a middle layer between cloud data centers and IoT-based devices/sensors. By distributing computing resources closer to edge devices, fog computing enables real-time data processing and analysis. However, one of the key aspects in... 

In the cloud computing environment, although many processing resources for application software with the volume of calculations The above is available, but it may not work for software that is sensitive to latency. In fact, due to the large distance between users and end devices to cloud servers, sending requests And the required data to the data centers requires a high bandwidth and therefore the data transfer time is also significant. In addition, cloud computing in platforms such as cloud-based IoT architecture faces other challenges such as connectivity, resource limitations of end devices, and security. In order to solve the challenges in the cloud computing environment and respond to... 

Cloud computing has a centralized computing architecture, such that services are provided by cloud servers at far distances from user devices. So, the data gathered by user devices must be sent to cloud servers. This is leading to various challenges, such as bandwidth, latency and privacy, especially in IoT where the number of devices is very large. The devices belong to different users with specific QoS requirements. Edge-based infrastructures or edge paradigms have the potential to tackle these challenges by utilizing devices and servers close to users. This thesis aims to present solutions for resource management problems in edge-based infrastructures, considering the QoS requirements of... 

Public-key cryptography is vital to secure digital communication. The classic instances of these cryptosystems are insecure against large-scale quantum computers. As a result, post-quantum cryptography has emerged as a replacement, which includes different categories. Isogeny-based schemes are one of the promising candidates mainly because of their smaller public key length. Due to high computational cost of such schemes, efficient implementations are significantly important. In this thesis, we have presented various solutions at three different abstraction layers. At the lowest layer, which deals with modular arithmetic, two hardware architectures are presented to perform modular...