Sharif Digital Repository

With the continual scaling of feature size, system failure due to soft errors is getting more frequent in CMOS technology. Soft errors have particularly severe effects in static random-access memory (SRAM)-based reconfigurable devices (SRDs) since an error in SRD configuration bits can permanently change the functionality of the system. Since interconnect resources are the dominant contributor to the overall configuration memory upsets in SRD-based designs, the system failure rate can be significantly reduced by mitigating soft errors in routing fabric. This paper first presents a comprehensive analysis of SRD switch box susceptibility to short and open faults. Based on this analysis, we... 

Promising advantages offered by resistive NonVolatile Memories (NVMs) have brought great attention to replace existing volatile memory technologies. While NVMs were primarily studied to be used in the memory hierarchy, they can also provide benefits in Field-Programmable Gate Arrays (FPGAs). One major limitation of employing NVMs in FPGAs is significant power and area overheads imposed by the Peripheral Circuitry (PC) of NVM configuration bits. In this paper, we investigate the applicability of different NVM technologies for configuration bits of FPGAs and propose a power-efficient reconfigurable architecture based on Phase Change Memory (PCM). The proposed PCM-based architecture has been... 

With the advent in technology and shrinking the transistor size down to nano scale, static power may become the dominant power component in Networks-on-Chip (NoCs). Powergating is an efficient technique to reduce the static power of under-utilized resources in different types of circuits. For NoC, routers are promising candidates for power gating, since they present high idle time. However, routers in a NoC are not usually idle for long consecutive cycles due to distribution of resources in NoC and its communication-based nature, even in low network utilizations. Therefore, power-gating loses its efficiency due to performance and power overhead of the packets that encounter powered-off... 

The increased leakage power of deep-nano technologies in the one hand, and exponential growth in the number of transistors in a given die particularly in Field-Programmable Gate Arrays (FPGAs) have resulted in an intensified rate of static power dissipation as well as power density. This ever-increasing static power consumption acts as a power wall to further integration of transistors and has caused the breakdown of Dennard scaling. To meet the available power budget and preclude reliability challenges associated with high power density, designers are obligated to restrict the active percentage of the chip by powering off a selective fraction of silicon die, referred to as Dark Silicon.... 

Nowadays, embedded processors are widely used in wide range of domains from low-power to safety-critical applications. By providing prominent features such as variant peripheral support and flexibility to partial or major design modifications, field-programmable gate arrays (FPGAs) are commonly used to implement either an entire embedded system or a hardware description language-based processor, known as soft-core processor. FPGA-based designs, however, suffer from high power consumption, large die area, and low performance that hinders common use of soft-core processors in low-power embedded systems. In this paper, we present an efficient reconfigurable architecture to implement soft-core... 

Continuous shrinking of transistor size to provide high computation capability along with low power consumption has been accompanied by reliability degradations due to e.g., aging phenomenon. In this regard, with huge number of configuration bits, Field-Programmable Gate Arrays (FPGAs) are more susceptible to aging since aging not only degrades the performance, it may additionally result in corrupting the configuration cells and thus causing permanent circuit malfunctioning. While several works have investigated the aging effects in Look-Up Tables (LUTs), the routing fabric of these devices is seldom studied - even though it contributes to the majority of FPGAs' resources and configuration... 

In this paper, we present a comprehensive analysis of the impact of aging on the interconnection network of field-programmable gate arrays (FPGAs) and propose novel approaches to mitigate the aging effects on the routing network. We first show the insignificant impact of aging on data integrity of FPGAs, i.e., static noise margin and soft error rate of the configuration cells, as well as we show the negligible impact of the mentioned degradations on the FPGA performance. As such, we focus on the performance degradation of datapath transistors. In this regard, we propose a routing accompanied by a placement algorithm that prevents constant stress on transistors by evenly distributing the... 

Mechanical characterization of fractures, i.e., identifying their characteristic parameters such as energy release rate, is crucial to assess the safety and stability of structural members. This is generally achieved using a combination of finite element analysis and optimization. Machine learning models are increasingly used to characterize engineering problems. While such models have shown impressive performance on smooth data, their performance diminishes significantly on data with discontinuities and sharp gradients. For fractures, this issue is more severe due to the singular solutions in the vicinity of the fracture tips. To resolve this difficulty, leveraging classical fracture... 

Channel distortion may dramatically degrade speech recognition performance in a distant environment. Authors in their recent work [1] proposed a novel spectral subtraction method which they named it maximum likelihood based spectral subtraction (MLBSS). They indicated that recognition performance could be improved dramatically by adjusting filter parameters based on recognition results. Previous results show effectiveness of this method in dealing with additive distortion. In this paper we propose an approach for increasing robustness of this method against channel distortion in distant talking environment. We add Cepstral Mean Normalization (CMN) in designing MLBSS filter and show that by... 

Despite the considerable effort has been put on the application of Non-Volatile Memories (NVMs) in Field-Programmable Gate Arrays FPGAs, previously suggested designs are not mature enough to substitute the state of-the-art SRAM-based counterparts mainly due to the inefficient building blocks and/or the overhead of programming structure which can impair their potential benefits. In this paper, we present a Resistive Random Access Memory RRAM-based FPGA architecture employing efficient Switch Box (SB) and Look-Up Table (LUT) designs with programming circuitry integrated in both SB and LUT designs that creates area and power efficient programmable components while precluding performance... 

An enhanced media access control (MAC) layer protocol that uses the signaling method benefits of the physical layer in order to provide different levels of quality to different users in optical code-division multiple-access (OCDMA) packet networks is presented. In the proposed network architecture the users are categorized into two classes of service, one having a higher quality level and the other having a lower quality level. 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 transmissions time to improve network performance. Through simulation... 

It was used CORSIKA simulations to investigate the characteristics of showers with energies comprised between 1014–1016eV. All simulations were performed for an altitude of 1200 m above sea level (altitude of Alborz Observatory at Tehran). By fitting the parabolic curve on the air shower front, its focal length can be obtained. The results of this study show that the focal length of the air shower front of gamma rays is separable from cosmic protons and this can be used as a hybrid for other methods of separating the two kind particles from each other. © 2022  

In this paper we address classification of Web content and in particular its application in the detection of pornographic Web pages. Filtering of undesirable Web content is mainly achieved based on blocking a specific Web address via searching it in a reference list of black URLs or doing a plain contextual analysis on the page by searching special keywords in the text. The main problem with current filtering methods is the requirement for instantly update of the URL list and also the high rate of over-blocking the usual pages. In this paper, we propose an intelligent approach which is based on using textual, profile, and visual features in a hierarchical structure classifier. Textual... 

In this paper, analysis of the throughput and delay in a spectrally phase-encoded optical code-division multiple-access (OCDMA) system, using a simplified slotted packet network protocol is conducted. Steady-state throughput and average packet delay of the system are derived. In evaluating the performance of the system, only multiple access interference is considered and other sources of noise are neglected. Comparing different systems with the fixed bit rate and chip duration leads us to conclude that increasing the code length will improve the performance of networks with small average activity; but in highly active networks, decreasing the code length will result in a significant...