Sharif Digital Repository

The widespread growth of Big Data and the evolution of Internet of Things (IoT) technologies enable cities to obtain valuable intelligence from a large amount of real-time produced data. In a Smart City, various IoT devices generate streams of data continuously which need to be analyzed within a short period of time; using some Big Data technique. Distributed stream processing frameworks (DSPFs) have the capacity to handle real-time data processing for Smart Cities. In this paper, we examine the applicability of employing distributed stream processing frameworks at the data processing layer of Smart City and appraising the current state of their adoption and maturity among the IoT... 

Modification of orthopedic implant surfaces through advanced nanoscale coating methods has made a major breakthrough in maximizing implantation success. Adjustable drug release and biocompatibility are among the most momentous features since they can significantly prevent the implantation failure. In this study, the potential of silk fibroin (SF) nanofibers fabricated via electrospinning, along with titanium oxide nanotube arrays (TNTs) formed through anodization, were exploited to produce a cyto-biocompatible, well-controlled drug delivery system. Highly-ordered TNTs were formed in an organic electrolyte solution within 2 h at the voltage of 60 V under temperature controlling (16 °C).... 

The Network-on-Chip (NoC) paradigm brings networks inside chips. We use the routing capabilities inside NoC to serve as a replacement for Virtual Method Table (VMT) for Object-Oriented (OO) designed hardware/software co-design systems where some methods could be implemented as hardware modules. This eliminates VMT area and performance overhead in OO co-designed embedded systems where resources are limited and where some functionality needs to be implemented in hardware to meet performance goals of the system. Our experimental results on real world embedded applications show up to 32.15% lower area and up to 5.1% higher speed compared to traditional implementation using VMT. © 2007 Elsevier... 

A reconfigurable cache architecture for object-oriented application-specific instruction set processors (ASIP) is presented in this paper. The embedded ASIPs we follow in this research are specifically designed to suit object-oriented applications and are synthesized form an object-oriented highlevel specification. The ASIPs are composed of a processor core along with a number of hardware functional units. In order to support concurrent execution of the functional units, we propose a cache architecture which is virtually divided into a number of partitions. The partition sizes can be dynamically changed depending on the run-time behavior of the application. Partitioning the cache not only... 

In this paper, we present an MPEG-2 video decoder implemented in our ODYSSEY design methodology. We start with an ASIP tailored to the JPEG decompression algorithm. We extend that ASIP by required software routines such that the extended ASIP can now perform MPEG2 decoding while still benefiting from hardware units common between JPEG and MPEG2. This demonstrates the ability of our approach in extending an already manufactured ASIP, which was tailored to a given application, such that it implements new, yet related applications. The implementation platform is a VirtexII-Pro FPGA. The hardware part is implemented in VHDL, and the software runs on a PowerPC processor. Experimental results show... 

The influence of electron beam irradiation on neat nylon 6 was manifested by formation of molecular branches deduced from increase in melt flow index and intrinsic viscosity. Crosslinking of nylon 6 was carried out using electron beam irradiation in presence of triallyl cyanurate (TAC). The crosslinked samples showed a high level of gel content. At a given dose, increasing the TAC level from 1% to 3% increased the gel content of the samples slightly and correspondingly decreased the percent of water absorption. The melting temperature decreased with increasing the dose and the TAC level. All samples containing TAC showed some decrease in crystallinity under exposure to electron beam. The... 

In-situ deposition of cupric oxide (CuO) thin films on fluorine-doped tin oxide is performed through a rapid microwave-assisted method. The duration of microwave (MW) irradiation is optimized in order to prepare efficient and stable photocathodes for photoelectrochemical (PEC) water splitting. We obtain CuO with a unique morphology consisted of intermingled nanosheets. We evaluate PEC performance of the photocathodes through Linear Sweep Voltammetry (LSV) and current stability analyses. The highest achieved photocurrent density is -1.15 mA.cm-2 at 0 V vs. RHE for the sample MW-irradiated for 60 min. This value is comparable or superior to several other CuO-based photocathodes prepared by... 

In this paper we discuss and analyze an enhanced media access control (MAC) layer protocol which uses the signaling method benefits of physical layer in order to provide different quality of service (QoS) levels in optical code-division multiple-access (OCDMA) packet networks. In the proposed network architecture the users are categorized into the high and low classes of service. Users of each class transmit at the same power level and different from the other classes' users. Also, the MAC of each user estimates the amount of interference on the channel and adjusts the packet transmission's time to improve network performance. Through simulation it is shown that the combination of... 

Within-die process variation is increasing in nanometer-scale process technologies. We observe that the same SRAM cell leaks differently under within-die process variations when storing 0 compared to 1; this difference can be up to 3 orders of magnitude at 60mV variation of threshold voltage (V th). Thus, leakage can be reduced if most often the values that dissipate less leakage are stored in the cache SRAM cells. We take advantage of this fact to reduce instruction-cache leakage by presenting three binary-optimization and software-level techniques: we (i) reorder instructions within basic-blocks so that their bits better match the less-leaky state of their corresponding cache cells, (ii)... 

In this study, the effects of ferrofluids on the forced convective heat transfer in a tube with a round cross section under constant heat flux in the laminar flow regime are investigated experimentally. For this purpose, an experimental setup was designed and built. Furthermore, the effects of an external magnetic field on the forced convective heat transfer were examined for various Reynolds numbers and volume concentrations. The parameters of magnetic field strength, magnetic field arrangement, the constancy or oscillation of the magnetic field and also its oscillatory mode were examined. As a result of the experimental studies, in the absence of a magnetic field enhancement in convective... 

Energy reduction in embedded processors is a must since most embedded systems run on batteries and processor energy reduction helps increase usage time before needing a recharge. Register files are among the most power consuming parts of a processor core. Register file power consumption mainly depends on its size (height as well as width), especially in newer technologies where leakage power is increasing. We provide a register file architecture that, depending on the application behavior, dynamically (i) adapts the width of individual registers, and (ii) puts partitions of temporarily unused registers into low-power mode, so as to save both static and dynamic power. We show that our scheme... 

MapReduce and its open source implementation, Hadoop, are the prevailing platforms for big data processing. MapReduce is a simple programming model for performing large computational problems in large-scale distributed systems. This model consists of two major phases: Map and Reduce. Between these two main phases, partitioner part is embedded which distributes produced keys by Map tasks among Reduce tasks. When the amount of keys and their associated values, which are called intermediate data, is huge, this part has significant impact on execution time of Reduce tasks, and consequently, completion time of jobs. In this paper, we present a network and resource aware key partitioner to... 

Engines that extract energy from low-grade heat sources, e.g., from other processes, have received considerable attention recently. The use of Fluidyne, which is a liquid piston Stirling engine, is quite popular. Herein, we explore the use of liquid-to-vapor phase change in a Fluidyne. This provides two considerable differentiators; (1) exploitation of very low temperature difference ΔT≈30 K, and (2) relatively low temperature ΔT≈330 K heat sources, for producing mechanical work, and thus electrical energy. The influence of three operating parameters, i.e., input heat flux, working fluid, and filling ratio, on the performance of the engine was characterized. Their optimum values, which yield...