Dielectric and Photo-Dielectric Properties of TlGaSeS Crystals

The room temperature, dark and photo-dielectric properties of the novel crystals TlGaSeS are investigated in the frequency, intensity and biasing voltage having ranges of ~ 1–120 MHz, 14–40 klux and 0–1 V, respectively. The crystals are observed to exhibit a dark high frequency effective dielectric constant value of ~ 10·65 × 10³ with a quality factor of ~ 8·84 × 10⁴ at ~ 120 MHz. The dielectric spectra showed sharp resonance– antiresonance peaks in the frequency range of ~ 25–250 kHz. When photoexcited, pronounced increase in the dielectric constant and in the quality factor values with increasing illumination intensity are observed. Signal amplification up to ~ 33% with improved signal quality up to ~ 29% is attainable via photoexcitation. On the other hand, the illuminated capacitance–voltage characteristics of the crystals reflected a downward shift in the voltage biasing and in the built-in voltage of the device that is associated with increase in the uncompensated carrier density. The increase in the dielectric constant with increasing illumination intensity is ascribed to the decrease in the crystal's resistance as a result of increased free carrier density. The light sensitivity of the crystals, the improved dielectric properties and the lower biasing voltage obtained via photoexcitation and the well-enhanced signal quality factor of the crystals make them promising candidates for optical communication systems.     

Feasibility analysis of solar photovoltaic array cladding on commercial towers in Doha,Qatar – a case study

Building-integrated photovoltaic (BIPV) technology has become a major area of research due to environ-mental concerns. This article studies the feasibility of cladding high-rise towers in Doha with solar photovoltaic modules. Specifically, the case of the Qatar Financial Centre (QFC) is discussed. The major aim of the work is to evaluate the technical feasibility, economic impact and environmental effects of using photovoltaic panels on commercial towers in Qatar. Experimental data on solar irradiance and the effect of shading on the QFC Tower are presented. Numerical calculations are done using solar pathfinder software. The studies show that, although there is a significant amount of saving in CO₂ emission by using BIPV on towers in Doha, the payback period is still very long due to the cheaper cost of grid electricity in Qatar and poor conversion efficiency of PV panels. The complete system layout is presented and viable solutions are investigated.     

基于视角转换的多视角步态识别方法

针对步态识别中步态视角变化、步态数据样本量少及较少利用步态时间信息等问题,提出一种基于视角转换的步态识别方法。通过VTM-GAN网络,将不同视角下的步态能量图及含有步态时间信息的彩色步态能量图,统一映射到保留步态信息最丰富的侧视图视角,以此突破步态识别中多视角的限制,在视角转换的基础上,通过构建侧视图下的步态正负样本对来扩充用于网络训练的数据,并采用基于距离度量的时空双流卷积神经网络作为步态识别网络。在CASIA-B数据集上的实验结果表明,该方法在各状态、各角度下的平均识别准确率达到92.5%,优于3DCNN、SST-MSCI等步态识别方法。     

On the Weighted Pseudo-Almost Periodic Solution for BAM Networks with Delays

In this paper, a class of Bidirectional Associative Memory neural networks with time-varying weights and continuously distributed delays is discussed. Sufficient conditions are obtained for the existence and uniqueness of weighted pseudo-almost periodic solution of the considered model and numerical examples are given to show the effectiveness of the obtained results.     

Performance analysis of a planted roof as a passive cooling technique in hot-humid tropics

Planted roofs are passive cooling techniques that reduce the thermal load of buildings. In this paper, the authors have developed a model for evaluating the cooling potential of green roofs. Transfer equations are solved using a finite difference scheme and Thomas algorithm. The study was conducted taking into account the Togolese climate conditions. The effect of Leaf Area Index (LAI) and Biot (Bi) number on diurnal variation of the Solar Heat gain Factor (SHF) is presented and analysed. A correlation for the estimation of the Solar Heat gain Factor as a function of LAI and Bi has been established. The results presented in terms of evapotranspiration (ET) and Solar Heat gains Factor (SHF) show notably that the foliage density and hence the vegetable canopy type selection influence the thermal efficiency of the bioclimatic insulation screen greatly. It was found that a larger LAI reduces the solar flux penetration, stabilizes the fluctuating values, and reduces the indoor air temperature.     

Effect of PEGylation on the stability of liposomes during nebulisation and in lung surfactant

Oral inhalation of anticancer drugs or drug delivery system is a novel therapeutic approach in the treatment of lung cancer and requires formulations which are sufficiently stabile during nebulisation and subsequent interaction with the surfactant lining of the lungs. In this study, we assessed the stability of plain and PEGylated transferrin-conjugated liposomes after nebulisation using two different nebulisers (i.e., air-jet and ultrasonic type). Furthermore, the integrity of the liposomal membranes was assessed after incubation in commercial lung surfactant solutions (Alveofact). All liposomal formulations showed no significant changes in their size after nebulisation, independent of the type of nebuliser or the liposomal formulation, respectively. However, PEGylation was of advantage when it came to interactions between liposomes and the surfactant lining of the lungs. PEGylated liposomes were significantly more stable and retained > 80% of their drug load over 48 h, which is more than sufficient time for the drug carriers to be taken up by transferrin receptor over-expressing cancer cells in the lung. In conclusion, PEGylated and plain Tf-conjugated liposomes are stable enough to undergo nebulisation in the course of an inhalational therapy, but PEG-stabilisation results in a higher degree of membrane integrity in lung surfactant.     

A group trust metric for identifying people of trust in online social networks

With the growth of social network services, the need for identifying trustworthy people has become a primary concern in order to protect users’ vast amounts of information from being misused by unreliable users. In this study, we propose the extended Advogato trust metric that facilitates the identification of trustworthy users associated with each individual user. By incorporating the strength of social relationships, we recursively diffuse a capacity of a target user throughout his/her personal network. Based on the capacity propagation, this paper also presents the capacity-first maximum flow method capable of finding the strongest path pertinent to discovering an ordered set of reliable users and preventing unreliable users from accessing personal networks. Experimental results demonstrate that our approach has advantages over existing representative methods in terms of both the discovery of reliable users and the preventability of unreliable users.     

High-aspect-ratio bulk micromachining of titanium

Recent process developments have permitted the highly anisotropic bulk micromachining of titanium microelectromechanical systems (MEMS). By using the metal anisotropic reactive ion etching with oxidation (MARIO) process, arbitrarily high-aspect-ratio structures with straight sidewalls and micrometre-scale features have been bulk micromachined into titanium substrates of various thicknesses, ranging from 0.5-mm sheet down to 10-microm free-standing titanium foils. Bulk micromachined structures are generally free of residual stresses and are preferred when large, rigid, flat and/or high-force actuators are desired. However, so far there has been a limited ability to select materials on the basis of specific application in bulk micromachining, primarily because of the predominance of MEMS processes dedicated to single-crystal silicon, such as silicon deep reactive ion etching. The MARIO process permits the creation of bulk titanium MEMS, which offers potential for the use of a set of material properties beyond those provided by traditional semiconductor-based MEMS. Consequently, the MARIO process enables the fabrication of novel devices that capitalize on these assets to yield enhanced functionalities that would not be possible with traditional micromechanical material systems.     

Combining local branching and descent method for solving the multiple-choice knapsack problem with setups

In this paper, the multiple-choice knapsack problem with setups is tackled with an iterative method, where both local branching and descent method cooperate. First, an iterative procedure is designed for solving a series of mixed integer programming problems combined with a special reduced subproblem; that is, a combined model built by injecting some valid cardinality constraints. Second, the local branching-based learning strategy is embedded into an iterative search to mimic the variable neighborhood descent method, such that the local branching strategy drives the search process for enhancing the quality of the solutions. Third, the proposed method is experimentally analyzed on benchmark instances extracted from the literature, where its provided (lower) bounds are compared to those reached by methods published in the literature and the Cplex solver. Finally, its performance is evaluated by providing a statistical analysis.