Sharif Digital Repository

Electric networks often consist of remote cities or villages with low population densities, which consume a considerably small amount of energy. This can be in the order of a few megawatts for places that are up to 100 km away from the source. Typical uncompensated primary distribution lines are not an effective option for these situations, since line loadability drastically decreases as the line length is increased. Increasing the voltage level, on the other hand, is not cost effective. This paper investigates different reactive compensation techniques for increasing the loadability of these lines. Effect of series capacitors, shunt capacitors and voltage regulating transformers in such... 

Flooding technique is widely using to manipulate sensor network essential activities such as synchronization, data gathering, network query and in-network information processing. Reliable and low latency data broadcasting is the primary goal in design of appropriate quality of service aware flooding algorithm. This paper proposes a new error-rate adaptive reliable data flooding strategy. Energy consumption which it the main limitation in sensor network, has been considered in optimal presented scheme. Also the tradeoff between reliability, power consumption and latency has been cared to achieve the finest devise. The simulation results have shown significant enhancement in quality of data... 

Wireless sensor networks consist of small nodes with sensing, computation, and wireless communicationr capabilities. Many routing protocols have been specifically designed for WSNs where energy awareness is an essential design issue. Routing protocols in WSNs might differ depending on the application and network architecture. In this article, a fault-tolerant and energy efficient routing protocol for wireless sensor networks is proposed This protocol is called Directed Flooding, and is a descendant of the Flooding routing protocol, which consumes less energy, while maintaining high levels of fault-tolerance. This is done by Tending data in a specific aperture instead of broadcasting, which... 

Concerns about the reliability of real-time embedded systems that employ dynamic voltage scaling has recently been highlighted [1,2,3], focusing on transient-fault-tolerance techniques based on time-redundancy. In this paper we analyze the usage of information redundancy in DVS-enabled systems with the aim of improving both the system tolerance to transient faults as well as the energy consumption. We demonstrate through a case study that it is possible to achieve both higher fault-tolerance and less energy using a combination of information and time redundancy when compared with using time redundancy alone. This even holds despite the impact of the information redundancy hardware overhead... 

Stochastic optimal control of a vehicle suspension on a random road is studied. The road roughness height is modelled as a filtered white noise stochastic process and a four-degree-of-freedom half-car model is used in the analysis. It is assumed that a sensor is mounted in the front bumper that measures the road irregularity at some distances in the front of the vehicle. Two other sensors also measure relative velocities of the vehicle body with respect to the unsprung masses in the vehicle suspension spaces. All measurements are assumed to be conducted in a noisy environment. The state variables of the vehicle system are estimated using a method similar to the Kalman filter. The suspension... 

Control of the air-handling units (AHU) is required to maintain satisfactory comfort conditions with low energy consumption. In the case of failure in sensor fusion systems of AHUs, full-order observers can be used as the supportive tool to provide an acceptable estimation of state variables. In this paper, a multivariable nonlinear model of the AHU is considered in the presence of uncertainties. The indoor temperature and relative humidity are controlled via manipulation of valve positions of air and cold water flow rates. In proposed hybrid control system, full and minimum-order observers are designed for the estimation of indoor temperature and relative humidity. Also, a regulator for... 

The graphics processing unit (GPU) is the most promising candidate platform for achieving faster improvements in peak processing speed, low latency and high performance. The highly programmable and multithreaded nature of GPUs makes them a remarkable candidate for general purpose computing. However, supporting non-graphics computing on graphics processors requires addressing several architectural challenges. In this paper, we focus on improving performance by better hiding long waiting time for transferring data from the slow global memory. Furthermore, we show that the proposed method can reduce power and energy. Reduction in access time to off-chip data has a noticeable role in reducing... 

Decimal multiplication is a frequent operation with inherent complexity in implementation. Commercial and financial applications require working with decimal numbers while it has been shown that if we convert decimal number to binary ones, this will negatively influence the preciseness required for these applications. Existing research works on parallel decimal multipliers have mainly focused on latency and area as two major factors to be improved. However, energy/power consumption is another prominent issue in today's digital systems. While the energy consumption of parallel decimal multipliers has not been addressed in previous works, in this paper we present a comparative study of... 

Reliability and energy consumption are two of the main constraints in wireless sensor networks (WSNs). In this paper, a novel energy efficient and high speed error control scheme is introduced that is based on the Redundant Residue Number System (RRNS) allowing real-time application of WSNs. The proposed approach employs a new 3-moduli set {22n+1, 2 2n1-1, 2n- 1 } and an efficient reverse converter which relies on the Mixed Radix Conversion (MRC) algorithm and achieves significant improvements both in terms of conversion delay and hardware design. In order to obtain error controllability, two-redundant-moduli set 23n+1 - 1, 24n+1 - 1 is also added to the main 3-moduli set. The theoretical... 

We consider a firm real-time system with a single processor working in two power modes depending on whether it is idle or executing a job. The system is equipped with dynamic thermal management through a cooling subsystem which can switch between two cooling modes. Real-time jobs which arrive to the system have stochastic properties and are prone to soft errors. A successful job is one that enters the system and completes its execution with no timing or soft error. Appropriateness of the system is evaluated based on its performance, temperature behavior, reliability, and energy consumption. It is noteworthy that these criteria have mutual interactions to each other: the stochastic nature of... 

A dual-mode power and performance optimized SRAM is presented. Given the fact that the power and speed associated with the cell access time are directly related to the sense amplifier offset a new optimization platform based on the hybrid offset-cancelled current sense amplifier (OCCSA) [1] is presented. It is shown that the speed and power overhead of the offset cancellation can be optimized in a multi-variable auto-calibration loop to achieve the lowest power or the highest performance mode. The flexibility of having two degrees of freedom in OCCSA offers a significant bitline delay reduction with minimum power sacrifice in the high performance mode. The proposed scheme is verified using a... 

The current of outgoing feeders are very important data transmitted over SCADA system. Monitoring of these currents can help dispatching engineers to detect abnormality in energy consumption trend and minor faults in distribution network. Statistical process control (SPC) is one of the capable approaches which can be used for this purpose. Statistical process control is based on categorizing variations into assignable causes and random causes. In current paper we described the methods which were used for finding assignable causes in load trend and short time load variation in Alborz province power distribution company pilot project. Although this approach is not developed completely and some... 

The bulk of the worldwide annual commercial production of ethylene is based on thermal cracking of petroleum hydrocarbons with steam. In this research, the effect of coil outlet temperature on the reactor yield has been studied. In order to investigate a reliable mathematical correlation, several data points were obtained by adjusting coil outlet temperature in a real plant. In order to investigate best coil outlet temperature, an objective function was represented. Based on the obtained mathematical correlation and the assumed objective function, it was found that best coil outlet temperature for investigating maximum income is 1,128 K  

In this paper, a new highly convergent, efficient, and fast response control technique entitled as fuzzy-Padé control method is introduced. It provides a simple methodology to exploit the heuristic knowledge in controlling a system. Fuzzy-Padé controllers originate from a unification of heuristic knowledge expressed as the rule base, and Padé approximants. In this method, fuzzy singleton rules are used to generate the rule base. Accordingly, unknown parameters in the Padé approximant are determined using these rules. The fuzzy-Padé controllers possess certain advantages over fuzzy controllers, and they can be applied in situations where fuzzy controllers previously failed. To demonstrate the... 

Wireless sensor networks (WSNs) consume energy for their sensing, computation, and communication. To extend the lifetime of the network, sensor nodes are equipped with energy storage devices. Recharging of their batteries is impossible in most applications. Therefore, energy consumption needs to be monitored and limited to extend the high performance operation of the network. In this network, the communication module consumes the highest amount of energy. This paper demonstrates that among several methods offered to reduce the energy consumption, data compression has the highest effect on the energy usage by reducing the number of bits to be broadcasted. To determine the energy efficiency of... 

To scavenge the energy from the environment and extend the network lifetime, some wireless sensor networks (WSNs) have been equipped with energy harvesters recently. However, the variable amount of environmental energy can affect the reliability of energy harvesting wireless sensor networks (EH-WSNs). In addition, data transmission over a wireless media is vulnerable. Hence, utilizing suitable error control schemes are necessary to improve the reliability. Regarding this point, Automatic Repeat Request (ARQ) and Cooperative ARQ (C-ARQ) schemes are applied in this generation of WSNs. Conventional ARQ as well as C-ARQ scheme are considered and examined through simulation. A comparative... 

Data aggregation is an efficient method to conserve energy by reducing packet transmissions in WSNs. However, providing end-to-end data reliability is a major challenge when the network uses data aggregation. In this case, a packet loss can miss a complete subtree of values, thus greatly affecting the final results. Data transmission in multiple paths can tolerate this problem, but it may incur some computation errors for duplicate-sensitive aggregates. In this paper, we propose a Flexible Overlay Multi-path data Aggregation protocol (FOMA) which uses the available path redundancy to deliver a correct aggregate result to the sink with high reliability in an energy-efficient manner. It... 

Multiple paths are mainly used in order to achieve higher throughput and reduce the end-to-end delivery latency as well. However, the overall network performance greatly suffers from the available interference between paths, even if node disjoint multipaths are used. This problem is highlighted more when dealing with transmission of the video data where the timeliness is of primary concern. In this paper, we propose a novel Interference-Aware Multipath routing for Video Delivery (IAMVD) in the realm of wireless multimedia sensor networks. It constructs multiple paths while considering the effect of different QoS requirements of multi-priority packets, without needing any hardware support for... 

This paper presents a novel routing protocol based on the Learning Automata method for large scale Wireless Sensor Networks (WSNs) codenamed DRLR (distributed reinforcement learning routing). In this method, each node is equipped with learning automata so that it can learn the best path to transmit data toward the sink. The approach proved to be efficient, reliable, and scalable. It also prevents routing hole by considering network density and average of energy levels available. The approach also increases network lifetime by balancing energy consumption. We compared our approach to two other methods (MMSPEED and EESPEED) and the simulation results show our algorithm to better meet... 

Networks on chip (NoC) have been proposed as a solution to mitigate complex on-chip communication problems. NoCs are composed of intellectual properties (IP) which are interconnected by on-chip switching fabrics. A step in the design process of NoCs is hardware virtualization which is mapping the IP cores onto the tiles of a chip. The communication among the IP cores greatly affects the performance and power consumption of NoCs which itself is deeply related to the placement of IPs onto the tiles of the network. Different mapping algorithms have been proposed for NoCs which allocate a set of IPs to given network topologies. In these mapping algorithms, there is a restriction which limits IPs...