On braced trapezoidal corrugated steel shear panels: An experimental and numerical study

In this study, a new system consisting of a combination of braces and steel infill panels called the braced corrugated steel shear panel (BCSSP) is presented. To obtain the hysteretic behavior of the proposed system, the quasi-static cyclic performances of two experimental specimens were first evaluated. The finite element modeling method was then verified based on the obtained experimental results. Additional numerical evaluations were carried out to investigate the effects of different parameters on the system. Subsequently, a relationship was established to estimate the buckling shear strength of the system without considering residual stresses. The results obtained from the parametric study indicate that the corrugated steel shear panel (CSSP) with the specifications of a = 30 mm, t = 2 mm, and θ = 90° had the highest energy dissipation capacity and ultimate strength while the CSSP with the specifications of a = 30 mm, t = 2 mm, and θ = 30° had the highest initial stiffness. It can thus be concluded that the latter CSSP has the best structural performance and that increasing the number of corrugations, corrugation angle, and plate thickness and decreasing the sub-panel width generally enhance the performance of CSSPs in terms of the stability of their hysteretic behaviors.     

High performance dye-sensitized solar cells (DSSCs) achieved via electrophoretic technique by optimizing of photoelectrode properties

This paper describes a simple method utilizing electrophoretic deposition (EPD) of commercial P25 nanoparticles (NPs) films on fluoride-doped tin oxide (FTO) substrate. In this process, voltage and the number of deposition cycles are well controlled to achieve TiO₂ film thickness of around 1.5–26 μm, without any mechanical compression processing. The experimental results indicate that the TiO₂ film thickness plays an important role as the photoelectrode in DSSCs because it adsorbs a large number of dye molecules which are responsible for electrons supply. Furthermore, it was found that effects of the bulk traps and surface states within the TiO₂ films on the recombination of the photo-injected electrons (electron–hole pairs) strongly depend on the TiO₂ electrode annealing temperature. Finally, a DSSC with a 24 μm thick TiO₂ film and annealed at 500 °C produced the highest conversion efficiency (η=6.56%, I_SC=16.4, V_OC=0.72, FF=0.55) with an incident solar energy of 100 mW/cm².     

On the Effects of Frequency Scaling Over Capacity Scaling in Underwater Networks—Part I: Extended Network Model

In this two-part paper, information-theoretic capacity scaling laws are analyzed in an underwater acoustic network with n regularly located nodes on a square, in which both bandwidth and received signal power can be limited significantly. Parts I and II deal with an extended network of unit node density and a dense network of unit area, respectively. In both cases, a narrow-band model is assumed where the carrier frequency is allowed to scale as a function of n, which is shown to be crucial for achieving the order optimality in multi-hop (MH) mechanisms. We first characterize an attenuation parameter that depends on the frequency scaling as well as the transmission distance. Upper and lower bounds on the capacity scaling are then derived. In Part I, we show that the upper bound on capacity for extended networks is inversely proportional to the attenuation parameter, thus resulting in a highly power-limited network. Interestingly, it is shown that the upper bound is intrinsically related to the attenuation parameter but not the spreading factor. Furthermore, we propose an achievable communication scheme based on the nearest-neighbor MH transmission, which is suitable due to the low propagation speed of acoustic channel, and show that it is order-optimal for all operating regimes of extended networks. Finally, these scaling results are extended to the case of random node deployments providing fundamental limits to more complex scenarios of extended underwater networks.     

CogNS: A Simulation Framework for Cognitive Radio Networks

Cognitive radio technology has been used to efficiently utilize the spectrum in wireless networks. Although many research studies have been done recently in the area of cognitive radio networks (CRNs), little effort has been made to propose a simulation framework for CRNs. In this paper, a simulation framework based on NS2 (CogNS) for cognitive radio networks is proposed. This framework can be used to investigate and evaluate the impact of lower layers, i.e., MAC and physical layer, on the transport and network layers protocols. Due to the importance of packet drop probability, end-to-end delay and throughput as QoS requirements in real-time reliable applications, these metrics are evaluated over CRNs through CogNS framework. Our simulations demonstrate that the design of new network and transport layer protocols over CRNs should be considered based on CR-related parameters such as activity model of primary users, sensing time and frequency.     

On the Effects of Frequency Scaling Over Capacity Scaling in Underwater Networks—Part II: Dense Network Model

This is the second in a two-part series of papers on information-theoretic capacity scaling laws for an underwater acoustic network. Part II focuses on a dense network scenario, where nodes are deployed in a unit area. By deriving a cut-set upper bound on the capacity scaling, we first show that there exists either a bandwidth or power limitation, or both, according to the operating regimes (i.e., path-loss attenuation regimes), thus yielding the upper bound that follows three fundamentally different information transfer arguments. In addition, an achievability result based on the multi-hop (MH) transmission is presented for dense networks. MH is shown to guarantee the order optimality under certain operating regimes. More specifically, it turns out that scaling the carrier frequency faster than or as $n^{1/4}$ is instrumental towards achieving the order optimality of the MH protocol.     

Optimized Ultrasound-Assisted Temperature-Controlled Ionic Liquid Microextraction Coupled with FAAS for Determination of Tin in Canned Foods

A simple and rapid method based on ultrasound-assisted temperature-controlled ionic liquid microextraction combined with flame atomic absorption spectrometry (FAAS) has been developed for determination of tin. In this method, Sn(IV)-ammonium pyrrolidinedithiocarbamate (APDC) complex was extracted into a small volume of 1-hexyl-3-methylimidazolium hexafluorophosphate as ionic liquid and after phase separation, the enriched analyte in the final solution is determined by FAAS. Experimental design approaches were used to obtain the best conditions. The variables of interest were temperature, pH, buffer volume, extraction time, centrifugation time and volumes of ionic liquid, methanol, and APDC. The Plackett–Burman design was employed for screening to determine the variables significantly affecting the extraction efficiency. Then, the significant factors were optimized by using a central composite design. In the optimal conditions the calibration graph was linear in the range of 0.10–6.0 mg?L^?1 with a correlation coefficient of 0.997. The limit of detection and relative standard deviation (n?=?5 for determination of 1.0 mg?L^?1) were 42 μg?L^?1 and 1.6 %, respectively. The preconcentration factor was calculated to be 52.7. Finally, the method was successfully applied to the determination of tin in various canned products including peach, pineapple and aloe vera juice, canned pea, and canned cheese.     

A Convenient and Efficient Protocol for the Synthesis of HBIW Catalyzed by Silica Nanoparticles under Ultrasound Irradiation

2,4,6,8,10,12-Hexabenzyl-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.0^5,9.0^3,11]dodecane (hexabenzylhexaazaisowurtzitane, HBIW) has been synthesized by the reaction of benzylamine and glyoxal (40% aqueous solution) in acetonitrile as a solvent catalyzed by silica nanoparticles (SiO₂ NPs, ca. 42 nm) under ultrasound irradiation. The effects of solvent, catalyst, and ultrasonic power are discussed. With optimized reaction conditions, HBIW was synthesized under the influence of ultrasound irradiation. Compared with conventional methods, the remarkable advantages of this method are the simple experimental procedure, shorter reaction time, and high product yield.     

Dependence of coupling coefficient and lasing wavelength on injection current in pure gain-coupled distributed feedback semiconductor lasers

A theoretical analysis of purely gain-coupled distributed feedback lasers (PGC-DFB) with antireflection facets is given. The effects of longitudinal non-uniformity of photon and carrier density above a threshold circumstance are considered. In addition, the influence of carrier-induced refractive index change on the coupling coefficient of the PGC-DFB structure is assumed. It is shown that the coupling coefficient in this structure varies with injected current and it gets a real part or an index coupled term. As a result the normalized coupling coefficient, κL, becomes a complex number. So, above the threshold condition, the PGC-DFB laser operates like a complex coupled one. Variation of the oscillation wavelength and the threshold gain of the PGC-DFB laser in terms of current is analyzed too. Numerical analysis shows that this structure has wavelength tunability with respect to current. The theoretical model is based on the self-consistent solution of coupled wave equations and the carrier rate equation by the transfer matrix method.     

A fast on-chip profiler memory using a pipelined binary tree

We introduce a novel memory architecture that can count the occurrences of patterns on a system's bus, a task known as profiling. Such profiling can serve a variety of purposes, like detecting a microprocessor's software hot spots or frequently used data values, which can be used to optimize various aspects of the system. The memory, which we call ProMem, is based on a pipelined binary search tree structure, yielding several beneficial features, including nonintrusiveness, accurate counts, excellent size and power efficiency, very fast access times, and the use of standard memories with only simple additional logic. The main limitation is that the set of potential patterns must be preloaded into the memory. We describe the ProMem architecture, and show excellent size and performance advantages compared with content-addressable memory (CAM) based designs.