Thermal conductivity and thermal boundary resistance of nanostructures

   

We present a fabrication process of low-cost superlattices and simulations related with the heat dissipation on them. The influence of the interfacial roughness on the thermal conductivity of semiconductor/semiconductor superlattices was studied by equilibrium and non-equilibrium molecular dynamics and on the Kapitza resistance of superlattice's interfaces by equilibrium molecular dynamics. The non-equilibrium method was the tool used for the prediction of the Kapitza resistance for a binary semiconductor/metal system. Physical explanations are provided for rationalizing the simulation results.     

Enhanced Sintering of TiNi Shape Memory Foams under Mg Vapor Atmosphere

TiNi alloy foams are promising candidates for biomaterials to be used as artificial orthopedic implant materials for bone replacement applications in biomedical sector. However, certain problems exist in their processing routes, such as formation of unwanted secondary intermetallic phases leading to brittleness and deterioration of shape memory and superelasticity characteristics; and the contamination during processing resulting in oxides and carbonitrides which affect mechanical properties negatively. Moreover, the eutectic reaction present in Ti-Ni binary system at 1391?K (1118?°C) prevents employment of higher sintering temperatures (and higher mechanical properties) even when equiatomic prealloyed powders are used because of Ni enrichment of TiNi matrix as a result of oxidation. It is essential to prevent oxidation of TiNi powders during processing for high-temperature (>1391?K i.e., 1118?°C) sintering practices. In the current study, magnesium powders were used as space holder material to produce TiNi foams with the porosities in the range of 40 to 65?pct. It has been found that magnesium prevents secondary phase formation and contamination. It also prevents liquid phase formation while enabling employment of higher sintering temperatures by two-step sintering processing: holding the sample at 1373?K (1100?°C) for 30?minutes, and subsequently sintering at temperatures higher than the eutectic temperature, 1391?K (1118?°C). By this procedure, magnesium may allow sintering up to temperatures close to the melting point of TiNi. TiNi foams produced with porosities in the range of 40 to 55?pct were found to be acceptable as implant materials in the light of their favorable mechanical properties.     

Some physicochemical properties and mineral contents of stirred yoghurts containing different fruit marmalades

In this study chemical properties and mineral levels of yoghurts containing different fruit marmalades were investigated. Cherry laurel, loquat fruit and kiwi marmalade were used to make the stirred yoghurts, and the calcium, phosphorus, sodium, magnesium, manganese, iron, zinc, copper, boron, lead, nickel, molybdenum, chromium, cadmium, cobalt levels were determined by an inductively coupled plasma optical emission spectrometer (ICP–OES). The total solid, fat, ash, pH, viscosity and syneresis contents of the yoghurt samples changed between 13.85–21.02%, 2.45–2.90%, 0.82–0.94%, 4.11–4.22, 2104–2454 cP and 42.0–47.0 mL/100 g, respectively. The mean concentrations in the yoghurts of these minerals were 104.66–118.94 calcium, 95.81–112.42 phosphorus and 13.47–15.04 magnesium as mg/100 g, 235.00–254.00 iron, 429.00–453.00 zinc and 70.45–122.90 copper as μg/100 g. The recommended dietary allowance (RDA) was calculated on the basis of the intake of one yoghurt portion (125 g).     

A fully automatic CAD-CTC system based on curvature analysis for standard and low-dose CT data

Computed tomography colonography (CTC) is a rapidly evolving noninvasive medical investigation that is viewed by radiologists as a potential screening technique for the detection of colorectal polyps. Due to the technical advances in CT system design, the volume of data required to be processed by radiologists has increased significantly, and as a consequence the manual analysis of this information has become an increasingly time consuming process whose results can be affected by inter- and intrauser variability. The aim of this paper is to detail the implementation of a fully integrated CAD-CTC system that is able to robustly identify the clinically significant polyps in the CT data. The CAD-CTC system described in this paper is a multistage implementation whose main system components are: 1) automatic colon segmentation; 2) candidate surface extraction; 3) feature extraction; and 4) classification. Our CAD-CTC system performs at 100% sensitivity for polyps larger than 10 mm, 92% sensitivity for polyps in the range 5 to 10 mm, and 57.14% sensitivity for polyps smaller than 5 mm with an average of 3.38 false positives per dataset. The developed system has been evaluated on synthetic and real patient CT data acquired with standard and low-dose radiation levels.     

A hybrid mobile object tracker based on the modified Cuckoo Search algorithm and the Kalman Filter

Most revolutionary algorithms are inspired from the behavior of natural species. This inspiration can be drawn from their reproductive behavior, flying mode, or even their ways of communication. One of the most efficient metaheuristics in a discrete search space is the Cuckoo Search algorithm, inspired by the Cuckoo?s reproductive behavior and combined with the Lévy flight pattern adopted by many animals and insects. In this paper, we present a new tracking approach, the Hybrid Kalman Cuckoo Search tracker, using a modified version of the Cuckoo Search algorithm combined with the well-known Kalman Filter. The Cuckoo Search algorithm is combined with the prediction step adopted by the Kalman Filter to enhance the initial population?s quality. Using the Hybrid Kalman Cuckoo Search tracker, we can efficiently explore the search space in order to locate an object?s position from one frame to the next. The Lévy flight model is also modified in order to re-adapt the Lévy step size as the algorithm approaches the desired solution. The Hybrid Kalman Cuckoo Search tracker is tested on a variety of datasets including one where we incorporated different situations, as well as some videos from the CAVIAR, SPEVI, and other datasets. The comparative study results show that the proposed algorithm outperforms the Particle Swarm Optimization based tracker, especially in terms of computation time.     

数据与模型协同驱动的智能光网络架构与关键技术

网络的规模升级和超大连接、超高带宽、超低时延应用的不断深化,对光传输网络资源利用和网络差异化服务提出了更高要求,使得传统模型驱动下的网络形态和配置方式面临挑战。基于数据与模型协同驱动思想,提出“3层3循环”架构及其“3可功能”特征的智能光网络技术方案,并对智能化实现技术展开研究,通过开发设计的智能传输网络平台对所提算法的性能进行测试,经验证,数据与模型协同驱动的智能光网络传输性能得到有效提升,为实现网络智能化提供了理论技术支撑。     

Modelling of a Cd<Subscript>1−x</Subscript>Zn<Subscript>x</Subscript>Te/ZnTe Single Quantum Well for Laser Diodes

In this paper, the carrier density, temperature and quantum well width effect have been investigated for the optical gain for a Cd_1?xZn_xTe/ZnTe Zinc-blend strained quantum well structure. The device emits laser radiations in green–yellow–orange. Our results showed that the optical gain significantly increases with the increasing of the carrier density. It also increases with the decreasing of the Zn concentration, the well width and the temperature. In addition, the optimal threshold current density values were determined for three alloy compositions as 0.7, 0.8 and 0.9.