External quantum efficiency response of thin silicon solar cell based on plasmonic scattering of indium and silver nanoparticles

This study characterized the plasmonic scattering effects of indium nanoparticles (In NPs) on the front surface and silver nanoparticles (Ag NPs) on the rear surface of a thin silicon solar cell according to external quantum efficiency (EQE) and photovoltaic current–voltage. The EQE response indicates that, at wavelengths of 300 to 800 nm, the ratio of the number of photo-carriers collected to the number of incident photons shining on a thin Si solar cell was enhanced by the In NPs, and at wavelengths of 1,000 to 1,200 nm, by the Ag NPs. These results demonstrate the effectiveness of combining the broadband plasmonic scattering of two metals in enhancing the overall photovoltaic performance of a thin silicon solar cell. Short-circuit current was increased by 31.88% (from 2.98 to 3.93 mA) and conversion efficiency was increased by 32.72% (from 9.81% to 13.02%), compared to bare thin Si solar cells.     

Adaptive backstepping control for an n-degree of freedom robotic manipulator based on combined state augmentation

The aim of this paper is to improve the tracking performance of a robotic manipulator by designing an adaptive controller and implementing it on the system. The proposed controller guarantees the system stability as well as good tracking performance in existence of nonlinearity and parameter uncertainties. The requirement to decrease the system response overshoot and steady state error as well as increasing speed of tracking for manipulators is essential to many manufacturers. To this mean, in this paper, the tracking error equations for an n-DOF manipulator are derived and the response characteristics are improved by augmenting a new state to the system equations. The stability of the closed-loop system is guaranteed based on the Lyapunov theory via backstepping control approach. The robotic manipulator model contains parametric uncertainties and many of the parameter values are unknown. To solve the problem, an adaption law is proposed via adaptive backstepping mechanism. Different experiments are carried out for a 2-DOF manipulator to show the effectiveness of the proposed approach and the results are compared with four of the recently revealed researches on control. Experimental results present the superiority of the state augmented adaptive backstepping in tracking the desired joint angles. Moreover, in order to present the industrial application of the proposed control method, it is simulated for a large industrial Scara manipulator.     

Wind effects on flame projection probability from a compartment with opposing openings

This paper investigates flame projection probability from a compartment with opposing openings under assisting wind environment. The effect of external wind on the flow conditions at the door, hot gas velocity at the window and flame projection probability was investigated. Results showed that when the external wind is absent or at low wind velocities, bidirectional flow can be seen at the door. With the increment of the wind velocity, the bidirectional flow will become unidirectional at low fuel supply rate. At high wind velocities, the unidirectional flow can be seen at the door regardless of the fuel supply rate. Correlations for hot gas velocity at the window are formulated based on the mass conservation of the flow in the compartment. The calculated results have a good agreement with the experimental data. Due to fluctuations of the gases ejected from the window, flames eject from the compartment intermittently. The intermittent characteristic of flame ejecting from the compartment is influenced by the temperature and velocity of the hot gas velocity at the window. The model to predict flame projection probability is modified based on previous study without external wind.     

On power of p systems using sequential and parallel rewriting

A new class of distributed computing models inspired from biology, that of P Systems, was recently introduced by Gh. P[acaron]un. Several variants of P Systems were already shown to be computationally universal, equal in power to Turing Machines. We investigate in this paper the power of computability of P Systems based on rewriting, with cooperation, priorities and external output. It is established that rewriting P Systems with priorities and two membranes is computationally universal, thereby making an improvement in the existing result that RE?RP ₃(Pri). We give a new model in P Systems stressing the importance of parallelism. The power of computability of such models is investigated by comparing them with classic mechanisms in L-Systems: TOL, EOL and ETOL Systems     

Improving strength,stiffness and ductility of CFDST columns by external confinement

Concrete-filled double-skin tubular (CFDST) column is one of the most efficient forms of column construction in which the steel tubes provides both axial strength and confining pressure to enhance the strength and ductility of the in-filled concrete. Compared with confined reinforced concrete columns, CFDST columns had stronger and more uniform confining pressure provided to the in-filled concrete by the steel tubes, which reduces the steel congestion problem for better concrete placing quality. However, a major shortcoming of the CFDST columns is the imperfect interface bonding that occurred at the elastic stage that reduces the elastic strength and stiffness of columns. To improve the situation, it is proposed in this study to use external steel rings to restrict the dilation of outer steel tube of CFDST columns. For verification, a series of uni-axial compression test was performed on some CFDST columns with external steel rings. From the results, it was found that the elastic strength, elastic stiffness and ductility were enhanced by installing the steel rings as external confinement. Lastly, a theoretical model for predicting the axial strength of confined CFDST columns has been developed.     

Enhancing light-extraction efficiency of OLEDs with high- and low-refractive-index organic–inorganic hybrid materials

High- and low-refractive-index hybrid materials were prepared by an in situ acid-free sol–gel process for internal and external light-extraction layers in organic light-emitting diodes (OLEDs). A random copolymer of methyl methacrylate (MMA) and 3-(trimethoxysilyl) propyl methacrylate (MSMA), poly(MMA-co-MSMA), which was capped with trialkoxysilane in MSMA units, was used as a precursor. The precursor was further reacted with titanium(IV) isopropoxide (TTIP) and tetraethyl orthosilicate (TEOS) to synthesize the high- and low-refractive-index hybrid materials, respectively, in which TiO₂ and SiO₂ nanoparticles were well dispersed, respectively, in the polymer matrix. After the reactions with TTIP and TEOS, the refractive index increased to 1.81 and decreased to 1.44 from 1.50 of the precursor, respectively. The luminance, power, and current efficiency of the OLED with an external light-extraction layer were enhanced by 21.3, 28.6, and 29.1%, respectively, those of the OLED with an internal light-extraction layer were increased by 62.4, 76.9, and 59.2%, respectively, and those of the device with combined ELEL and ILEL were enhanced by 62.7, 77.2, and 59.3%, respectively, when compared to values for the reference OLED without an internal or external light-extraction layer. These results indicate that high- and low-refractive-index materials are desirable for enhancement in light-extraction efficiency, and they can provide practical solutions for various applications such as OLED displays and lighting.     

Critical heat flux and mass loss rate for extinction of flaming combustion of timber

The critical mass loss rate and critical heat flux for self-extinction of flaming combustion during steady-state burning of timber was measured in this study for a range of timber species. A vertical mass loss calorimeter was used to provide the external heat flux and to measure the mass loss of the timber samples. The results showed that the critical mass loss rate was dependent upon the timber species but did not show a clear dependency with the timber density. Critical mass loss rates and heat fluxes for self-extinction exist for each of the timber species tested for both the solid timber and cross laminated timber (CLT). Debonding of both the char layer and the individual lamella of the CLT caused increased mass loss rates, re-ignition after self-extinction and increased flame lengths. Both char and ply fall-off were observed.     

ActiveSort: Efficient external sorting using active SSDs in the MapReduce framework

In the last decades, there has been an explosion in the volume of data to be processed by data-intensive computing applications. As a result, processing I/O operations efficiently has become an important challenge. SSDs (solid state drives) are an effective solution that not only improves the I/O throughput but also reduces the amount of I/O transfer by adopting the concept of active SSDs. Active SSDs offload a part of the data-processing tasks usually performed in the host to the SSD. Offloading data-processing tasks removes extra data transfer and improves the overall data processing performance.In this work, we propose ActiveSort, a novel mechanism to improve the external sorting algorithm using the concept of active SSDs. External sorting is used extensively in the data-intensive computing frameworks such as Hadoop. By performing merge operations on-the-fly within the SSD, ActiveSort reduces the amount of I/O transfer and improves the performance of external sorting in Hadoop. Our evaluation results on a real SSD platform indicate that the Hadoop applications using ActiveSort outperform the original Hadoop by up to 36.1%. ActiveSort reduces the amount of write by up to 40.4%, thereby improving the lifetime of the SSD.     

I/O-efficient join dependency testing,Loomis–Whitney join,and triangle enumeration

We revisit two fundamental problems in database theory. The join-dependency (JD) testing problem is to determine whether a given JD holds on a relation r. We prove that the problem is NP-hard even if the JD involves only relations each of which has only two attributes. The JD-existence testing problem is to determine if there exists any non-trivial JD satisfied by r. We present an I/O-efficient algorithm in the external memory model, which in fact settles the closely related Loomis–Whitney enumeration problem. As a side product, we solve the triangle enumeration problem with the optimal I/O-complexity, improving a recent result of Pagh and Silvestri in PODS'14.     

An analytical method for the buckling analysis of cylindrical shells with non-axisymmetric thickness variations under external pressure

This article presents an analytical method for the buckling analysis of laterally pressured cylindrical shells with non-axisymmetric thickness variations. The previous results for thickness variations under external pressure are reviewed firstly. Then, a general analytical method that combines the perturbation method and Fourier series expansion is developed to derive buckling load formulas, which is in terms of thickness variation parameter up to arbitrary order. A classical non-axisymmetric thickness variation is discussed in detail by the presented analytical method. When non-axisymmetric modal thickness variation becomes axisymmetric, the buckling loads degenerate to the known results. Furthermore, the influence of circumferential modal thickness variation with mode corresponding to twice the circumferential buckling mode on the buckling of laterally pressured cylindrical shells is analytically investigated and the results show a great agreement with previous numerical ones by Gusic et al. Thus we confirm the presented method. In addition to theoretical analysis, calculations and comparisons are also performed. The general analytical method presented in the article can be utilized to determine the buckling loads of shells with general thickness variations.