Sharif Digital Repository

This paper presents mathematical modelling of joint lot sizing and scheduling problem in job shop environment under a set of working conditions. The main feature of the problem is to deal with flexible machines able to change their working speeds, known as process compressibility. Furthermore, produced items should be assembled together to make final products. In other words, the products have a multilevel structure, shown with bill of materials. As the problem is proved to be strongly NP-hard, it is solved by a memetic algorithm here. Computational experiences on the data of Mega Motor company are reported. Also, further experiences on random test data confirm the performance of the... 

In Phase-Change Memory (PCM), the number of writes a cell can take before wearing-out is limited and highly varied due to unbalanced write traffic and process variation. After the failure of weak cells and in presence of large number of failed lines, some techniques have been proposed to further prolong the lifetime of a PCM device by remapping failed lines to spares and salvage a PCM device with graceful degradation. Others rely on handling failures through inter-line pairing. Observations reveal that most of cells in a line are healthy when the line is marked as faulty by any of these proposals. To overcome this deficiency, we propose Intra-line Level Pairing(ILP), a technique that... 

Iran, as a developing country, will be confronted with a significant increase in electricity demand in future years. Being a petroleum producing country has resulted in extreme subsidies for energy production from fossilized resources such as oil and gas. This issue is one of the most important factors regarding underdevelopment of renewable energies in Iran. Expansive use of fossil resources in providing the necessary energy has resulted in Iran being among the 20 countries that have a share in the 75% spread of greenhouse gases. This issue has resulted in greater attention on behalf of the energy sectors policy makers regarding renewable energies, especially wind. Awareness regarding the... 

In this chapter, we first introduce one shifting mechanisms in order to further prolonging the lifetime of a phase change memory (PCM) device, reducing the write rate to PCM cells, and handling cell failures when hard faults occur. In this line, Byte-level Shifting Scheme (BLESS) is addressed and reduces write pressure over hot cells of blocks. Additionally, we illustrate that using the MLC capability of PCM and manipulating the data block to recover faulty cells can also be used for error recovery purpose. Next, we propose another intra-line level pairing scheme (ILP). This novel recovery mechanism can statically partition a data block into a small number of groups and efficiently benefits... 

To address the problem of fast degradation in PCM main memory systems in the presence of severe cell wear-out, this chapter introduces and evaluates some ways to deal with hard error issues in phase change memory. Our observation reveals when some memory pages reach their endurance limits, other pages may be far from their limits even when using a perfect wear-leveling. Recent studies have proposed redirection or correction schemes to alleviate this problem, but all suffer from poor throughput or latency. In this chapter, we also propose On-demand page paired PCM (OD3P) memory system. Our technique mitigates the problem of fast failure of pages by redirecting them onto other healthy pages,... 

Semantic technology is widely used in distributed computational environments to increase interoperability and machine readability of information through giving semantics to the underlying information and resources. Semantic-awareness, distribution and interoperability of new generation of distributed systems demand an authorisation model and framework that satisfies essential authorisation requirements of such environments. In this study, the authors propose an authorisation model and framework based on multi-security-domain architecture for distributed semantic-aware environments. The proposed framework is founded based on the MA(DL)2 logic, which enables policy specification and inference... 

This study proposes a new fault detection method for modular multilevel converter (MMC) semiconductor power switches. While in common MMCs, the cells capacitor voltages are measured directly for control purposes, in this study voltage measurement point changes to the cell output terminal improving fault diagnosis ability. Based on this measurement reconfiguration, a novel fault detection algorithm is designed for MMCs semiconductor power switches. The open circuit and short circuit faults are detected based on unconformity between modules output voltage and switching signals. Simulation and experimental results confirm accurate and fast operation of the proposed method in faulty cell... 

This paper provides a developed mathematical model to derive the optimal integrated lot sizing in a multi-level supply chain with imperfect quality products. The developed mathematical model has a bi-objective function, with conflicting goals, minimizing the chain inventory costs and maximizing the chain total profit aided to find optimum policy for integrated lot sizing. We further actualize the problem by assuming multiple stochastic constraints. The mathematical formulation of the problem is stochastic, nonlinear, and large. In this regard, the interior point algorithm that is developed as more effective algorithm with less iteration is used for solving the recent convex nonlinear model.... 

A rescheduling method for new order arrival is presented based on the concept of dynamic pegging in multi-level production. Upon the arrival of new, unplanned orders, dynamic pegging enables the re-assignment of the Work-In-Progress (WIP) to the existing or newly arrived orders in such a way that the cost of rescheduling is minimized. A simple yet inspiring Mixed Integer Programming (MIP) model is proposed that combines dynamic pegging with rescheduling. The resulting schedules are compared with the ones obtained from two other basic rescheduling approaches. Analysis of the comparisons confirm the superiority of the proposed method in terms of total rescheduling costs. © 2019  

This paper presents the results of the shared task with the aim of arousal level recognition for the competition held in conjunction with the 27th Iranian Conference on Electrical Engineering (ICEE 2019). A database annotated with arousal level labels released by Research Center for Development of Advanced Technologies. The contest was held on arousal database according to a defined protocol. Three teams were able to enter into the final stage of the competition according to compare their performance measure with the baseline method. The baseline method is proposed by the data owner. The aim of this paper is outlining the database, protocol design, and providing an overview of top-ranked... 

All of the presented solutions in this book focused on using MLC phase change memory (PCM) due to density advantage and prolonging PCM lifetime. However, resistance drift can be one of the challenging issues for MLC PCMs. While it is desired to have the density advantage of MLC, the trade-off is resistance drift. Since MLCs have closely separated resistance regions, drift has a chance of overlapping intermediate regions. It may then bring out either single bit or multi-bit soft error. Indeed, drift source is related to the semi amorphous resistance regions that are metastable vs time and temperature while crystalline resistance proves to be stable across time and temperature. This chapter... 

This chapter evaluates viewpoints on the Phase Change Memory (PCM) devices and materials entailing multi-level cell (MLC) phase change memory as well as its trade-offs. This chapter lists the main difficulties related to PCMs and possible recommendations to address those challenges. The next chapters introduce some simple techniques to alleviate some of the problems listed here. © 2020 Elsevier Inc  

An efficient and reliable Multi-Level Cell (MLC) Spin-Transfer Torque Random Access Memory (STT-RAM) is proposed based on a Drop-And-Rearrange Approach, called DARA. Since CNN models are rather robust, less important bits are dropped, allowing important bits to be written in safe and reliable Single-Level Cell mode. Also, bits are rearranged to make the representation better aligned with memory cell characteristics. Bits with higher impact on the features value are stored in safer bit positions reducing the chance of read/write circuits to malfunction. Experimental results show that our approach provides comparable to error-free scenario reliability level, while doubling the bandwidth and... 

In general, decomposition methods can facilitate the process of solving sophisticated and heterogonous problems in the area of software development and engineering. These approaches are assisting to decompose problems based on different disciplines, characteristics and functionalities that is results into increasing the computational efficiency (e.g. parallel processing/computing) and accelerate the software changing process, software modifications and error tracking. Essentially, these approaches contribute to the degree of modularity to decompose a complex problem into different sub-problems and to focus on local objectives. There are different approaches that are used to decompose a... 

Hybrid Multi-Level Cache Architectures (HCAs) are promising solutions for the growing need of high-performance and cost-efficient data storage systems. HCAs employ a high endurable memory as the first-level cache and a Solid-State Drive (SSD) as the second-level cache. Spin-Transfer Torque Magnetic RAM (STT-MRAM) is one of the most promising candidates for the first-level cache of HCAs because of its high endurance and DRAM-comparable performance along with non-volatility. However, STT-MRAM faces with three major reliability challenges named Read Disturbance, Write Failure, and Retention Failure. To provide a reliable HCA, the reliability challenges of STT-MRAM should be carefully addressed....