Sharif Digital Repository

Research on Wireless Body Area Networks (WBAN) has witnessed constant advances in small and low power integrated electronic circuits as well as wireless communication schemes for remote monitoring of patients. As such, high reliability anomaly detection has emerged as an important characteristic especially in detection of system faults and abnormal physiological measurements. This work studies the reliability of WBANs by utilizing a Markov-based chain model and considering hardware failure rate, patient health status, and accuracy of anomaly detection algorithms containing Detection Rate (DR), False Positive Rate (FPR), and accuracy of transient fault correction measures. The proposed... 

Malfunction of ultrasonic transducers is one of the most common factors affecting the quality of medical ultrasound images. In this work, the effect of electrical fatigue in piezoelectric transducers on the image quality is investigated and subsequently compensated. To this end, through a combination of simulation and controlled experimental and clinical evaluations, the effect of fatigue and its compensation is realized. Initially, the electrical fatigue is simulated by reducing the piezoelectric permittivity and piezoelectric constant parameters based on finite element method (FEM). Next, the transducer's electromechanical impulse response is obtained, and the quality of reconstructed... 

Quality of medical ultrasound images is negatively affected by common defective elements in the ultrasonic transducer arrays. In this work, radio frequency (RF) signals from weak elements with low sensitivity are restored using an adaptive nonblind signal deconvolution method. For this purpose, the electromechanical impulse response of each element in the transducer must be measured. Initially, the negative effects of the RF signals recorded from each element are removed by Wiener deconvolution of RF signals through the measured impulse responses. Then to restore the RF signals, the deconvolution result is convolved with the reference electromechanical impulse response, corresponding to the... 

The purpose of this study is to investigate production of high quality ammonium uranyl carbonate (AUC) from “uranyl nitrate + ammonium bicarbonate”, or “uranyl nitrate + sodium carbonate” precursor solutions, by controlled injection of ammonium carbonate solution which could be applicable in material testing reactor (MTR) fuel production plant for recycling of rejected uranium oxide powder. The experimental observations revealed: at pHs higher than 6, precipitation proceeds with formation of no intermediate, thus ensuing a better morphology and size distribution of the AUC products. The results of scanning electron microscopy, X-ray diffraction, particle size analysis, and uranium content... 

A methodology is developed for the design of optimum viscous fluid passive energy dissipation systems using pole assignment active control algorithm. In this method, the procedure to assign the new structural poles is slightly modified such that the resulting structural properties (i.e., the optimum locations of system poles) can be achieved merely by modification of structural stiffness and addition of a passive control system. A combination of stiffness reduction and increase of damping is utilized to reduce both acceleration and displacement response. It is shown that the control systems designed using this method provide structural performances slightly better than or close to those of... 

A practical procedure is developed for the design of passive control systems using viscous fluid dampers for nonlinear structures. The design methodology takes advantage of the modification of the damping, strength, and stiffness properties of the structure to achieve the desired relative displacement and absolute acceleration response. For this purpose, a study of poles in the complex plane is used to determine the required changes in the dynamic properties of nonlinear structures. Furthermore, a relatively simple relation between the ductility demands of highly damped single- and multiple-degree-of-freedom (SDF and MDF respectively) systems is established to reduce the computational burden... 

A strategy is developed for design of passive control systems for structures experiencing inelastic deformations during earthquake loading. Besides the addition of passive energy dissipation devices, the proposed method suggests the required changes to the stiffness and strength of the structure, to reduce the absolute acceleration and relative deformation responses simultaneously. For this purpose, the locations and amounts of modifications in stiffness, strength and damping are determined by a sliding mode control algorithm to consider the nonlinear behavior of the structure. Being originally designed for active control, the sliding mode algorithm is modified to facilitate the extraction... 

ABSTARCT: A practical procedure is developed for the design of passive control systems using viscous fluid dampers for nonlinear structures. The design methodology takes advantage of the modification of the damping, strength, and stiffness properties of the structure to achieve the desired relative displacement and absolute acceleration response. For this purpose, a study of poles in the complex plane is used to determine the required changes in the dynamic properties of nonlinear structures. Furthermore, a relatively simple relation between the ductility demands of highly damped single- and multiple-degree-of-freedom (SDF and MDF respectively) systems is established to reduce the... 

Carbonaceous radioactive waste is produced by adsorption of effluent gases of UF6 production line, on a bed of charcoal. Current research was aimed at developing a process for recovery of uranium from this waste in a laboratory and at pilot scale. As a first step, leaching of uranium from carbonaceous radioactive waste was undertaken by successive steps using Al(NO3)3 and nitric acid, the former used to eliminate corrosivity of the F− ions. The stoichiometry of reaction between F− and Al3+ ions form complexes ranging from AlF2+, AlF2+ to AlF3 depending upon their molar ratio. The results showed that the increase of NO3−/U ratio increased the uranium leaching efficiency. Presence of some... 

Let G be a graph. The minimum number of colors needed to color the edges of G is called the chromatic index of G and is denoted by x0(G). It is well known that δ(G) ≤ x0(G) ≤ δ(G) + 1, for any graph G, whereδ(G) denotes the maximum degree of G. A graph G is said to be class 1 if x0(G) = δ(G) and class 2 if x0(G) = δ(G)+1. Also, Gδ is the induced subgraph on all vertices of degreeδ(G). Let f : V(G) ! N be a function. An f -coloring of a graph G is a coloring of the edges of E(G) such that each color appears at each vertex v 2 V(G) at most f (v) times. The minimum number of colors needed to f -color G is called the f -chromatic index of G and is denoted by x0f (G). It was shown that for every... 

Single-rate synchronous digital hierarchy (SDH) networks contain one master block and several slave blocks and the slaves will synchronize themselves by the master clock frequency. However, the clock frequencies of master and slaves are different in multi-rate SDH networks and hence, the slaves require a synchronization circuit to match their clock frequencies with the master clock frequency. This research presents an efficient synchronization circuit for such networks. The proposed circuit occupies smaller area than the prior circuit and requires no clock alignment for its implementation. The circuit constraints are described and the maximum clock frequencies of master and slaves are... 

Latency-insensitive design (LID) is a correct by-construction methodology for system on chip design that prevents multiple iterations in synchronous system design. However, one problem in the LID is system throughput reduction. In this study, a protocol is proposed to increase the throughput of internal cores in the latency-insensitive systems when there are several repetitive structures. The validation of the protocol is checked for latency equivalency in various system graphs. A shell wrapper to implement the protocol is described and superimposed logic gates for the shell wrapper are formulated. Simulation is performed for 12 randomly generated systems and four actual systems. The... 

Let G be a graph and H be an abelian group. For every subset SH a map φ:E(G)→S is called an S-flow. For a given S-flow of G, and every v∈V(G), define s(v)=∑uv∈E(G)φ(uv). Let k∈H. We say that a graph G admits a k-sum S-flow if there is an S-flow such that for each vertex v,s(v)=k. We prove that if G is a connected bipartite graph with two parts X={x1,⋯,xr}, Y={y1,⋯, ys} and c1,⋯,cr,d1,⋯, ds are real numbers, then there is an R-flow such that s( xi)=ci and s(yj)=dj, for 1≤i≤r,1≤j≤s if and only if ∑i=1rci=∑j=1s dj. Also, it is shown that if G is a connected non-bipartite graph and c1,⋯,cn are arbitrary integers, then there is a Z-flow such that s(vi)=ci, for i=1, ⋯,n if and only if the number... 

Communication wire delay between multiple blocks is becoming a critical issue in System on Chip (SoC) design. Scheduling-based Latency-Insensitive Design (LID) is a method to alleviate wire delays by utilizing a central scheduling scheme for periodic clock gating of the blocks. The scheduling scheme resides in shift registers as sequences of '1' and '0' bits. In many systems, these sequences are too long, and have large area overhead. This problem indisposes the implementation of the scheduling based protocol. This paper proposes an algorithm that finds sequences with shorter lengths in comparison with the prior algorithm. On synthetic/random test cases, the algorithm gives 45% reduction on... 

Delay in communication wires causes design iterations in system-on-chip. Latency-insensitive design copes with this issue by encapsulating each core in a shell wrapper and inserting buffers in the wires to separate the design of core from that of communication wires. Scheduling-based latency-insensitive protocol is a methodology which employs shift registers for periodic clock gating of blocks instead of the shell wrappers. In many cases, the bit sequences inside the shift registers are too long and therefore consume a large area. This study presents a heuristic algorithm that optimises the bit sequences and produces them with shorter lengths compared with the existing method. The algorithm... 

Let G be a graph. Assume that l and k are two natural numbers. An l-sum flow on a graph G is an assignment of non-zero real numbers to the edges of G such that for every vertex v of G the sum of values of all edges incident with v equals l. An l-sum k-flow is an l-sum flow with values from the set {±1,…, ±(k — 1)}. Recently, it was proved that for every r, r ≥ 3, r ≠ 5, every r-regular graph admits a 0-sum 5-flow. In this paper we settle a conjecture by showing that every 5-regular graph admits a 0-sum 5-flow. Moreover, we prove that every r-regular graph of even order admits a 1-sum 5-flow  

This paper quantifies the difference in resource demand between modern and classic NoC workloads. In the paper, we show that modern workloads are able to better utilize higher numbers of VCs and smaller C factors in order to attain performance and energy efficiency. This is because of the high throughput and possible local congestions in their traffic pattern. As a result, such workloads are more suitable for concurrency and redundancy energy reduction techniques where the voltage and frequency are reduced simultaneously and the increased power budget is used for introducing additional resources to the network in order to improve the performance  

In this research MPA capped CdTe nanocrystals with sizes around 2.7-3.5 nm were grown in aqueous solution. The process was performed through the reaction of NaHTe with MPA and CdCl2 solution in high temperature. The synthesis was carried out in two different states of standard and modified forms. In the modified synthesis, the hydrazine hydrate material was added to the MPA plus CdCl2 solution before injection. The evolution of the nanocrystals size and PL quantum yield was monitored during the heating time for the growth. The results demonstrated that for the standard synthesis the growth rate was slow. The CdTe nanocrystals with high PL quantum yields were achieved in more than 10 h of... 

Simulation, design and fabrication of a sealing enclosure is carried out for a NaI(Tl) 2″×2″ detector, to be used as in situ gamma radioactivity measurement system in marine environment. Effect of sealing enclosure on performance of the system in laboratory and marine environment (distinct tank with 10 m3 volume) were studied using point sources. The marine volumetric efficiency for radiation with 1461 keV energy (from 40K) is measured with KCl volumetric liquid source diluted in distinct tank. The experimental and simulated efficiency values agreed well. Marine volumetric efficiency calibration curve is calculated for 60 keV to 1461 keV energy with Monte Carlo method. This curve indicates... 

Due to the accelerated climate change, it is anticipated that the number and severity of natural disasters such as hurricanes, blizzards, and floods will be increased in the coming years. In this regard, this paper presents a distribution system planning model to improve the system resilience against hurricane. A scenario-based mathematical model is proposed to capture the random nature of weather events. Moreover, a stochastic optimization model is developed to simultaneously harden the distribution lines and place different types of distributed generation (DG) units such as microturbines (MTs), wind turbines (WTs), and photovoltaic cells (PVs). The conditional value at risk (CVaR) is used...