Sharif Digital Repository

We study quantum information transmission in a Heisenberg-XY chain where qubits are affected by quasi-local environment action and compare it with the case of local action of the environment. We find that for open boundary conditions the former situation always improves quantum state transfer process, especially for short chains. In contrast, for closed boundary conditions quasi-local environment results advantageous in the strong noise regime. When the noise strength is comparable with the XY interaction strength, the state transfer fidelity through chain of odd/even number of qubits in presence of quasi-local environment results smaller/greater than that in presence of local environment. ©... 

In recent years Open Source Software programs have caused great changes in software world. Open Source software development is something beyond a method of software development or technology. As a result, using open source software development has diverse aspects. In this article the open source software development has been studied and investigated through reviewing some of the carried out works. © 2008 IEEE  

This paper presents a dynamic programming methodology for finding the optimum preventive maintenance schedule of generating units of a GENCO in open power systems. The objective function for the GENCO is to sell electricity as much as possible, according to the market price forecast. Various constraints such as generation capacity, duration of maintenance and maintenance crew are taken into account. In a case study, introducing a GENCO with six generating units, and implementing dynamic programming, we obtain the optimal maintenance schedule over the planning period. © 2002 IEEE  

Estimation of parameters is a pivotal task throughout science and technology. The quantum Cramér-Rao bound provides a fundamental limit of precision allowed to be achieved under quantum theory. For closed quantum systems, it has been shown how the estimation precision depends on the underlying dynamics. Here, we propose a general formulation for metrology scenarios in open quantum systems, aiming to relate the precision more directly to properties of the underlying dynamics. This feature may be employed to enhance an estimation precision, e.g., by quantum control techniques. Specifically, we derive a Cramér-Rao bound for a fairly large class of open system dynamics, which is governed by a... 

In this paper, system identification techniques are applied to accurately characterize the frequency behavior of a commercially available but with unknown characteristics of a photoplethysmography (under the commercial name of Pulse Sensor). Although claimed to be open-source, the electronic schematic of this device does not allow for a full characterization of it. Therefore a second order auto-regressive with exogenous input model has been employed to find the frequency response of this system. An optical excitation circuit was developed to send a pseudo-random signal to the Pulse Sensor. Results show that the model is able to reproduce the output with a fitness of 89.7 %. The obtained... 

In this paper, we present a new approach to localize a bug in the software source file hierarchy. The proposed approach uses log files of the revision control system and bug reports information in open bug repository of open source projects to train a Support Vector Machine (SVM) classifier. Our approach employs textual information in summary and description of bugs reported to the bug repository, in order to form machine learning features. The class labels are revision paths of fixed issues, as recorded in the log file of the revision control system. Given an unseen bug instance, the trained classifier can predict which part of the software source file hierarchy (revision path) is more... 

Hybrid Mobile Applications are a new generation of mobile applications that have recently introduced new security challenges. In these applications, untrusted web content, such as an advertisement inside an embedded browser, has the same privileges as the entire application and can directly access the device resources. Unfortunately, existing access control mechanisms are very coarse-grained and do not provide adequate facilities for fine-grained access rule definition and enforcement in hybrid mobile applications. In this paper, we propose a fine-grained access control mechanism for privilege separation in hybrid mobile applications. Our proposed access control mechanism, called... 

In recent years, high interest in using Virtual Machines (VMs) in data centers and cloud computing has significantly increased the demand for high-performance data storage systems. A straightforward approach to providing a high-performance storage system is using Solid-State Drives (SSDs). Inclusion of SSDs in storage systems, however, imposes significantly higher cost compared to Hard Disk Drives (HDDs). Recent studies suggest using SSDs as a caching layer for HDD-based storage subsystems in virtualized platforms. Such studies neglect to address the endurance and cost of SSDs, which can significantly affect the efficiency of I/O caching. Moreover, previous studies only configure the cache... 

Code reuse has well-known benefits on code quality, coding efficiency, and maintenance. Open Source Software (OSS) programmers gladly share their own code and they happily reuse others’. Social programming platforms like GitHub have normalized code foraging via their common platforms, enabling code search and reuse across different projects. Removing project borders may facilitate more efficient code foraging, and consequently faster programming. But looking for code across projects takes longer and, once found, may be more challenging to tailor to one’s needs. Learning how much code reuse goes on across projects, and identifying emerging patterns in past cross-project search behavior may... 

Code reuse has well-known benefits on code quality, coding efficiency, and maintenance. Open Source Software (OSS) programmers gladly share their own code and they happily reuse others’. Social programming platforms like GitHub have normalized code foraging via their common platforms, enabling code search and reuse across different projects. Removing project borders may facilitate more efficient code foraging, and consequently faster programming. But looking for code across projects takes longer and, once found, may be more challenging to tailor to one’s needs. Learning how much code reuse goes on across projects, and identifying emerging patterns in past cross-project search behavior may... 

The process of fluid flow displacement in porous media has recently gained great prominence owing to its widespread usage in a variety of industries, especially in the case of pore scale investigations. Although, many studies have been conducted to address pore-scale investigations in both modeling and experimental approaches, the role of interfacial tension and contact angle on pore-scale phenomena is less focused. In this work, direct pore-scale modeling was used to precisely examine the effect of interfacial tension and contact angle on the fluid flow at the microscale. Also, several pore-scale mechanisms, including Haines jump and dynamic breakup mechanisms, were observed. Therefore, the... 

Regression testing activities greatly reduce the risk of faulty software release. However, the size of the test suites grows throughout the development process, resulting in time-consuming execution of the test suite and delayed feedback to the software development team. This has urged the need for approaches such as test case prioritization (TCP) and test-suite reduction to reach better results in case of limited resources. In this regard, proposing approaches that use auxiliary sources of data such as bug history can be interesting. We aim to propose an approach for TCP that takes into account test case coverage data, bug history, and test case diversification. To evaluate this approach we... 

Data reduction technologies have proven their effectiveness to decrease the ever-growing demands on storage system capacities, but also introduce new complexity in the system I/O stack that can easily invalidate well-known best practices. In this paper, we conduct an extensive set of experiments on an enterprise all-flash storage (AFS) system equipped with an open-source data reduction module, i.e., RedHat VDO, and reveal novel observations on the performance gap between the state-of-the-art and the optimal AFS stack with integrated data reduction. We then offer cross-layer optimizations to enhance the performance of AFS, which range from deriving new optimal hardware RAID configurations up... 

Data reduction technologies have proven their effectiveness to decrease the ever-growing demands on storage system capacities, but also introduce new complexity in the system I/O stack that can easily invalidate well-known best practices. In this paper, we conduct an extensive set of experiments on an enterprise all-flash storage (AFS) system equipped with an open-source data reduction module, i.e., RedHat VDO, and reveal novel observations on the performance gap between the state-of-the-art and the optimal AFS stack with integrated data reduction. We then offer cross-layer optimizations to enhance the performance of AFS, which range from deriving new optimal hardware RAID configurations up... 

A gas turbine shaft is generally exposed to high-temperature gases and may seriously be affected and overheated duetotemperature fluctuationsinthe combustion chamber. Vortex flow inthe combustion chamber may increase the heat release rate and combustion efficiency, as well as control the location of energy release. However, this may result in excessive temperature on the combustor equipment and gas turbine shaft. In this study, a new gas turbine combustion chamber implementing a liner around the shaft and the liquid-fuel feeding system is designed and fabricated. The influences of parameters such as the Reynolds number and the equivalence ratio are studied. Experimental results are compared... 

Many mobile applications running on smartphones and wear- able devices would potentially benefit from the accuracy and scalability of deep CNN-based machine learning algorithms. However, performance and energy consumption limitations make the execution of such computationally intensive algorithms on mobile devices prohibitive. We present a GPU- accelerated library, dubbed CNNdroid [1], for execution of trained deep CNNs on Android-based mobile devices. Empirical evaluations show that CNNdroid achieves up to 60X speedup and 130X energy saving on current mobile devices. The CNNdroid open source library is available for download at https://github.com/ENCP/CNNdroid  

Nowadays MapReduce and its open source implementation, Apache Hadoop, are the most widespread solutions for handling massive dataset on clusters of commodity hardware. At the expense of a somewhat reduced performance in comparison to HPC technologies, the MapReduce framework provides fault tolerance and automatic parallelization without any efforts by developers. Since in many cases Hadoop is adopted to support business critical activities, it is often important to predict with fair confidence the execution time of submitted jobs, for instance when SLAs are established with end-users. In this work, we propose and validate a hybrid approach exploiting both queuing networks and support vector... 

Unsteady cloud cavitation phenomenon is an important subject due to its undesirable effects in various applications such as ship propeller, rudder and hydraulic machinery systems. We present an efficient passive control method to control the cavitation instabilities which may be caused by the shedding of cavity structures in the vicinity of the solid surface of an immersible body. We proposed a passive control method so called Cylindrical Cavitating-bubble Generators (CCGs) on the surface of a benchmark hydrofoil and analyzed the effects of this passive controller on the dynamics of the unsteady cloud cavitation. First we modeled the unsteady cavitating flow around the hydrofoil without CCGs... 

I/O caching techniques are widely employed in enterprise storage systems in order to enhance performance of I/O intensive applications in large-scale data centers. Due to higher performance compared to Hard Disk Drives (HDDs) and lower price and nonvolatility compared to Dynamic Random-Access Memories (DRAM), Flash-based Solid-State Drives (SSDs) are used as a main media in the caching layer of storage systems. Although SSDs are known as non-volatile devices but recent studies have reported large number of data failures due to power outage in SSDs. To overcome the reliability implications of SSD-based I/O caching schemes, RAID-1 (mirrored) configuration is commonly used to avoid data loss...