Effect of Microstructure on the Tribological and Mechanical Properties of CuO-Doped 3Y-TZP Ceramics

Dense 8 mol% CuO-doped 3Y-TZP ceramics were prepared by pressureless sintering for 8 h at 1500° and 1550°C, respectively. Transmission electron spectroscopy revealed that the ceramic sintered at 1500°C exhibits grain boundaries free of any amorphous phase, while crystalline copper-oxide grains were found in the zirconia matrix, whereas the sample sintered at 1550°C contains a Cu-rich amorphous grain boundary layer. The tribological behavior of these materials was tested under dry-sliding conditions using a pin-on-disk tribometer. The material sintered at 1500°C showed self-lubrication resulting in a low coefficient of friction ( f ) of 0.2–0.3 and a low specific wear rate ( k ) ≪ 10⁻⁶ mm³·(N·m)⁻¹. In contrast, the material sintered at 1550°C showed poor tribological behavior ( f =0.8–0.9; k ≫ 10⁻⁶ mm³·(N·m)⁻¹ under the same conditions. The difference in the tribological behavior of these two materials was interpreted on the basis of mechanical properties and microstructural characteristics.     

Air impingement and intermittent drying: Application to apple and to mango

An original drying process combining air impingement and intermittent drying was studied on apple slices and mango cubes. The influence of four operating parameters (air velocity, drying/tempering periods, upper height, and air temperature) on the drying time and on the drying rate was evaluated. Continuous and intermittent drying were compared. The intermittency α = 1/7 (τ_on = 10 seconds and τ_off = 60 seconds) gave the best results. A time savings of 54% for apple and 67% for mango was reached. In continuous drying, a time savings of 4620 seconds was observed by increasing the air velocity from 6 to 40 m s^?1 for apple. Air temperatures of 328 K for apple and of 328 K or 338 K for mango were determined as optimum to prevent case‐hardening. Experimental results were fitted with the analytical solution of Fick's second law and the modified Page equation (average values R² = 0.985 and 0.961, for apple and mango, respectively). For both products, the apparent moisture diffusivity D_app, the drying constant k, the drying coefficient n, and the activation energy E_a, were identified. Activation energies calculated from the analytical solution were 30.3 and 36.8 kJ mol^?1 and were 25.4 and 30.0 kJ mol^?1 using the modified Page equation for apple and mango, respectively. Mango has an increased temperature sensitivity and thus will need less energy for drying than apple.     

Comparing the Performance of Organic Solvent Nanofiltration Membranes in Non-Polar Solvents

Organic solvent nanofiltration (OSN) is gradually expanding from academic research to industrial implementation. The need for membranes with low and sharp molecular weight cutoffs that are able to operate under aggressive OSN conditions is increasing. However, the lack of comparable and uniform performance data frustrates the screening and membrane selection for processes. Here, a collaboration is presented between several academic and industrial partners analyzing the separation performance of 10 different membranes using three model process mixtures. Membrane materials range from classic polymeric and thin film composites (TFCs) to hybrid ceramic types. The model solutions were chosen to mimic cases relevant to today's industrial use: relatively low molar mass solutes (330–550 Da) in n-heptane, toluene, and anisole.     

Crystal structures and phase transformation of deuterated lithium imide, Li2ND

Half-Heusler compounds of Sn-doped TiCoSb “TiCoSn_xSb_1−x (x = 0.0, 0.01, and 0.05)” were prepared and their thermoelectric properties were measured above room temperature. From the EDX analysis, all the samples have three phases: the TiCoSn_xSb_1−x, Co-rich, and Ti-rich phases. The values of the thermoelectric power increase with Sn doping, and a positive thermoelectric power is obtained in the sample of TiCoSn_0.05Sb_0.95. The thermal conductivity decreases both with increasing temperature and with Sn content. The maximum value of ZT for p-type material is 0.030 at 988 K in the sample of TiCoSn_0.05Sb_0.95.     

一种基于高斯混合模型的轨迹预测算法

在智能交通控制系统、军事数字化战场、辅助驾驶系统中,实时、精确、可靠的移动对象不确定性轨迹预测具有极高的应用价值.智能轨迹预测不仅可以提供精准的基于位置的服务,而且可以提前监测和预判交通状况,进而推荐最佳路线,已经成为移动对象数据库研究的热点,亟需设计准确而高效的位置预测方法.针对现有方法的不足,提出了基于高斯混合模型的轨迹预测方法GMTP,主要步骤包括:(1) 针对复杂运动模式利用高斯混合模型建模;(2) 利用高斯混合模型计算不同运动模式的概率分布,进而将轨迹数据划分为不同分量;(3) 利用高斯过程回归预测移动对象最可能的运动轨迹.GMTP是高斯非线性概率统计模型,其优势在于:计算结果不仅是位置预测值,更是关于移动对象未来所有可能运动轨迹的概率分布,可以利用概率统计分布特性获得某种运动模式(如匀加速运动)下的位置预测.大量真实轨迹数据集上的实验结果表明:与相同参数设置下的高斯回归预测和卡尔曼滤波预测法相比,GMTP的预测准确性平均提高了22.2%和23.8%,预测时间平均缩减了92.7%和95.9%.     

Scalable digital hardware for a trapped ion quantum computer

Quantum Information Processing - Many of the challenges of scaling quantum computer hardware lie at the interface between the qubits and the classical control signals used to manipulate them....     

Validation of GOES and MODIS active fire detection products using ASTER and ETM+ data

In this study we implemented a comprehensive analysis to validate the MODIS and GOES satellite active fire detection products (MOD14 and WFABBA, respectively) and characterize their major sources of omission and commission errors which have important implications for a large community of fire data users. Our analyses were primarily based on the use of 30 m resolution ASTER and ETM+ imagery as our validation data. We found that at the 50% true positive detection probability mark, WFABBA requires four times more active fire area than is necessary for MOD14 to achieve the same probability of detection, despite the 16× factor separating the nominal spatial resolutions of the two products. Approximately 75% and 95% of all fires sampled were omitted by the MOD14 and WFABBA instantaneous products, respectively; whereas an omission error of 38% was obtained for WFABBA when considering the 30-minute interval of the GOES data. Commission errors for MOD14 and WFABBA were found to be similar and highly dependent on the vegetation conditions of the areas imaged, with the larger commission errors (approximately 35%) estimated over regions of active deforestation. Nonetheless, the vast majority (> 80%) of the commission errors were indeed associated with recent burning activity where scars could be visually confirmed in the higher resolution data. Differences in thermal dynamics of vegetated and non-vegetated areas were found to produce a reduction of approximately 50% in the commission errors estimated towards the hours of maximum fire activity (i.e., early-afternoon hours) which coincided with the MODIS/Aqua overpass. Lastly, we demonstrate the potential use of temporal metrics applied to the mid-infrared bands of MODIS and GOES data to reduce the commission errors found with the validation analyses.     

Optimization of clamped circular piezoelectric composite actuators

This paper addresses the design of clamped circular piezoceramic composite unimorph and bimorph configurations, specifically the conflicting requirements of maximum volume displacement for a prescribed bandwidth. An optimization problem is formulated that implements analytical solutions for unimorph and bimorph configurations using laminated plate theory, including the use of oppositely polarized piezoceramic patches. A range of actuator geometric parameters are studied, and bounds for volume displacement and natural frequency of optimal designs are determined and presented via design curves. In the selected design space, Pareto optimization results for unimorph and bimorph configurations show that optimal volume displacement is related to the bandwidth by a universal power law such that the product of the square of the natural frequency and the displaced volume, a “gain-bandwidth” product, is a constant. Characteristic trends are also described that are independent of the actuator radius for the Pareto optimal piezoceramic patch thickness and radius versus normalized bandwidth. The results are relevant, for example, in the design of zero-net mass-flux or synthetic jet actuators used in flow control applications.     

A new,flexible and widely applicable software package for the simulation of one-dimensional moisture flow: SoWaM

Most one-dimensional soil moisture flow simulation models have restricted applicability due to (amongst other things): i) insufficient user flexibility; ii) a lack of user friendliness; iii) dependency on scale, temporal and/or spatial, and iv) fixed boundary conditions. Therefore, we developed a simple and highly flexible software package to simulate, visualize and analyze 1-D moisture flow in soils: SoWaM (Soil Water Model). The package has a modular setup and consists of a range of tools to visualize, analyze and compare input data and results. Soil hydraulic properties for each specified soil layer can be defined by either Van Genuchten parameters or cubical splines. Since the model does not impose limits on element size or time interval, it is possible to perform simulations in very high detail, both spatially and temporally. Furthermore, four different criteria for irrigation scheduling have been implemented. The SoWaM package provides an accurate, simple and highly flexible tool to simulate soil moisture flow and to evaluate the effects of various factors on soil water movement, such as timing and amount of irrigation, soil hydraulic properties and soil layering. Results of a case study are presented to illustrate model performance.     

The use of pervasive sensing for behaviour profiling — a survey

With the maturity of sensing and pervasive computing techniques, extensive research is being carried out in using different sensing techniques for understanding human behaviour. An introduction to key modalities of pervasive sensing is presented. Behaviour modelling is then highlighted with a focus on probabilistic models. The survey discusses discriminative approaches as well as relevant work on behaviour pattern clustering and variability. The influence of interacting with people and objects in the environment is also discussed. Finally, challenges and new research opportunities are highlighted.