Effects of cationic CTAB and anionic SDBS surfactants on the performance of Zn–MnO2 alkaline batteries

Inhibiting properties of two kinds of surfactant, cationic cetyl trimethyl ammonium bromide (CTAB) and anionic sodium dodecyl benzene sulfonate (SDBS) with three different concentrations, in relation to zinc passivation have been explained in the primary Zn/MnO₂ alkaline batteries. Discharge performance of alkaline cell affected by utilization of surfactant in anodic gel. Therefore, electrochemical properties of anodic zinc have been investigated by cyclic voltammetry, X-ray diffraction, scanning electron microscopy (SEM) and ac impedance techniques. The results show that alkaline cell with 0.01 g l⁻¹ of anionic SDBS surfactant decreased effectively the rate of zinc-passivation reaction. Also, it exhibited ZnO morphology with smaller grain size, causing longer service life gradually, step by step.     

Highly improved electrooxidation of formaldehyde on nickel/poly (o-toluidine)/Triton X-100 film modified carbon nanotube paste electrode

In present work, o-toluidine (OT) monomer is electropolymerized in the presence of an aqueous acidic solution containing Triton X-100 (TX-100) non-ionic surfactant onto multi-walled carbon nanotube paste electrode (CNTPE). The as-prepared substrate is used as a porous matrix for dispersion of Ni (II) ions by immersing the modified electrode in a nickel (II) sulfate solution. The modified electrodes are characterized by field emission scanning electron microscopy (FE-SEM) and electrochemical methods. The electrochemical characterization of the nickel/poly (o-toluidine)/Triton X-100 film modified carbon nanotube paste electrode (Ni/POT (TX-100)/MCNTPE) exhibits redox behavior of Ni(III)/Ni(II) couple in alkaline medium. It has been shown that POT/TX-100 film at surface of the CNTPE improves efficiency of the catalyst toward formaldehyde electrooxidation. Moreover, the effects of various parameters such as TX-100 concentration, formaldehyde concentration, OT concentration, film thickness and accumulation time on the electrooxidation of formaldehyde as well as long-term stability of the Ni/POT (TX-100)/MCNTPE have also been investigated.     

A new practical interference mitigation scheme for interference cognitive radio networks

In this paper, a new practical dirty paper coding scheme and its extension is proposed for interference mitigation of a single TV broadcast station in uplink and downlink of a cognitive radio network using both a single secondary user (SU) and multiple SU scenarios. In the single SU scenario, which is called interference cognitive radio channel, derived simulation results show that the transmission rate of the SU archives the capacity of an AWGN channel with the cost of a 2.5 dB extra signal‐to‐noise ratio. In the sequel, the proposed scheme is extended to a multiple SU scenario using direct sequence spread spectrum technique in both uplink and downlink considering a TV band. Derived simulation results show that the number of supportable SUs in our proposed scheme increases to a fully loaded scenario of the same multiuser direct sequence spread spectrum system. Copyright © 2012 John Wiley & Sons, Ltd.     

HVD: horizontal-vertical-diagonal error detecting and correcting code to protect against with soft errors

This paper presents a high level error detection and correction method called HVD code to tolerate multiple bit upsets (MBUs) occurred in memory cells. The proposed method uses parity codes in four directions in a data part to assure the reliability of memories. The proposed method is very powerful in error detection while its error correction coverage is also acceptable considering its low computing latency. HVD code is useful for applications whose high error detection coverage is very important such as memory systems. Of course, this code can be used in combination with other protection codes which have high correction coverage and low detection coverage. The proposed method is evaluated using more than one billion multiple fault injection experiments. Multiple bit flips were randomly injected in different segments of a memory system and the fault detection and correction coverages are calculated. Results show that 100% of the injected faults can be detected. We proved that, this method can correct up to three bit upsets. Some hardware implementation issues are investigated to show tradeoffs between different implementation parameters of HVD method.     

Wideband smart antenna theory using rectangular array structures

Smart antenna techniques at the base station can dramatically improve the performance of the mobile radio system by employing spatial filtering. The design of a fully spatial signal processor using rectangular array configuration is proposed. Two-dimensional (2-D) spatial filters that can be implemented by microstrip technology are capable of filtering the received signal in the angular domain as well as the frequency domain. Furthermore, it has wideband properties and, hence, eliminates the requirement of different antenna spacing for applications including various carrier frequencies. The desired frequency selectivity of the smart antenna can be combined with compensation of the undesired frequency performance of a single antenna element, and the result is quite satisfactory for practical implementation. In addition, if the elements of the array are not perfectly omnidirectional or frequency independent, we can compensate for these deficiencies in the design algorithm. Two different algorithms for calculating the real-valued weights of the antenna elements are proposed. The first algorithm is more complex but leads to sharper beams and controlled performance. The second method is simpler but has wider beam and lower fractional bandwidth. Some computer simulation results demonstrating the directional beam patterns of the designed beamformers are also presented.     

A Fast Statistical Soft Error Rate Estimation Method for Nano-scale Combinational Circuits

Nano-scale digital integrated circuits are getting increasingly vulnerable to soft errors due to aggressive technology scaling. On the other hand, the impacts of process variations on characteristics of the circuits in nano era make statistical approaches as an unavoidable option for soft error rate estimation procedure. In this paper, we present a novel statistical Soft Error Rate estimation framework. The vulnerability of the circuits to soft errors is analyzed using a newly defined concept called Statistical Vulnerability Window (SVW). SVW is an inference of the necessary conditions for a Single Event Transient (SET) to cause observable errors in the given circuit. The SER is calculated using a probabilistic formulation based on the parameters of SVWs. Experimental results show that the proposed method provides considerable speedup (about 5 orders of magnitude) with less than 5 % accuracy loss when compared to Monte-Carlo SPICE simulations. In addition, the proposed framework, keeps its efficiency when considering a full spectrum charge collections (more than 36X speedups compared to the most recently published similar work).     

去除局部破损混凝土后钢筋混凝土梁受弯性能理论分析

在钢筋混凝土梁修复加固的过程中 ,常常可能去除梁上部分破损的混凝土 ,使钢筋外露 ,在荷载作用下 ,造成梁的力学性能发生变化。基于对钢筋混凝土梁变形分析 ,利用数值分析方法 ,详细讨论了在忽略梁剪切变形的条件下 ,去除局部破损混凝土、受拉钢筋暴露的钢筋混凝土梁的理论分析方法。给出了计算去除局部破损混凝土、部分受拉钢筋暴露的钢筋混凝土简支梁挠度和承载力的具体分析步骤和计算公式 ,计算结果和试验结果吻合良好。     

Multi-criteria optimal design of stiffened plates-II. Mathematical modelling of the optimal design of longitudinally stiffened plates

In the second part of these series of papers we present the mathematical modelling of the multi-criteria optimization problem of longitudinally stiffened plates. This leads to a non-linear multi-criteria optimization problem with a finite number of side-conditions. As an application we consider the optimal design of such plates where the weight should be as small as possible and the ultimate buckling load as high as possible. The chosen design variables are the number, the thickness and the height of the stiffeners for a specific plate thickness.For the computation of the optimal points the multi-criteria optimization problem is transformed to a family of ordinary optimization problems using a method developed in Ref.¹ (Segundas Jornadas Latino Americanas de Matematica Aplicada, 1983, 2, 483–495). An investigation of the special side-conditions of the considered optimal design problem leads to a simplification of the method of Ref.¹ The optimal design problem for weight minimization and for maximization of the ultimate buckling load is considered explicitly. Some numerical examples conclude the second part of the paper.