Quantitative Measurements of the Critical Impeller Speed for Solid‐Liquid Suspensions

A quantitative methodology for particle suspension assessment is presented. A new parameter, f_mov/tot, the ratio of the mean number of moving particles to the total number of particles, is introduced to evaluate the minimum speed required to just suspend solids. This approach is tested to investigate the impact of impeller clearance on the minimum impeller speed, N_js, in a vessel when using a radial flow Rushton turbine. Flow patterns and power numbers obtained experimentally and computationally support the suspension findings. Image analysis is an appropriate method for determining N_js. Lowering the impeller clearance reduces the speed required for particle suspension with a change of flow pattern from a radial discharge with two loops to a single loop scouring the vessel base. The power number also falls markedly at the two‐to‐one loop transition as does the strain rate near the base.     

Effects of larval crowding and nutrient limitation on male phenotype,reproductive investment and strategy in Ephestia kuehniella Zeller (Insecta: Lepidoptera)

Food shortage experienced by juvenile insects affects adult morphology and life-history traits. Developmental plasticity and trade-off between ecological and sexual traits helps maximise individual fitness. Ephestia kuehniella were reared at different larval densities to investigate phenotypic shifts in adult males. Variation in ecological traits (sizes of forewing, head and thorax and adult longevity) and sexual traits (valva and aedeagus, sperm number, mating frequency) were compared. Males that emerged from highest density population (800) had lower body mass and small forewings, head and thorax, suggesting that they could not completely compensate for food shortage. The allometric relationship between body mass and forewing length also changed, and these males had relatively longer wings. This arrangement may enhance dispersal and assist in mate-searching at higher densities. Males from all larval densities achieved similar mating frequency but those from higher density produced fewer eupyrene sperm and had shorter adult lifespan. By mating more frequently and maintaining apyrene sperm production, males increase their reproductive success at sperm competition observed at higher densities. Food stress associated with high density populations did not affect valva and aedeagus size indicating that these traits may be insensitive to external environmental changes because they incur fitness costs to males.     

水质集对分析评价模型的不足与改进

针对现有水质集对分析模型在指标联系数计算和根据综合联系数进行等级识别过程中存在的不足,首先通过划分实测值对评价等级的关系区间,建立了改进的联系数算法;而后基于属性测度理论建立了改进的趋同程度公式和置信度评判原则;最后以五里湖为研究对象进行了水质评估。结果表明,改进的集对分析模型能够处理劣Ⅴ类和越大越优指标的联系数计算,并克服了传统集对分析模型在指标联系数计算和综合等级识别中的逻辑错误。     

WiFi-Mesh网络规划方法研究

本文主要针对WiFi-Mesh网络的规划方法进行分析和研究,对规划过程中所涉及到的各种实际问题——如跳数选择、站址选择、频点规划等方面进行分析总结.     

Rapid Quantification of Live Cell Receptors Using Bioluminescence in a Flow‐Based Microfluidic Device

The number of receptors expressed by cells plays an important role in controlling cell signaling events, thus determining its behaviour, state and fate. Current methods of quantifying receptors on cells are either laborious or do not maintain the cells in their native form. Here, a method integrating highly sensitive bioluminescence, high precision microfluidics and small footprint of lensfree optics is developed to quantify cell surface receptors. This method is safe to use, less laborious, and faster than the conventional radiolabelling and near field scanning methods. It is also more sensitive than fluorescence based assays and is ideal for high throughput screening. In quantifying β₁ adrenergic receptors expressed on the surface of H9c2 cardiomyocytes, this method yields receptor numbers from 3.12 × 10⁵ to 9.36 × 10⁵ receptors/cell which are comparable with current methods. This can serve as a very good platform for rapid quantification of receptor numbers in ligand/drug binding and receptor characterization studies, which is an important part of pharmaceutical and biological research.     

Small samples do not cause greater accuracy—but clear data may cause small samples: Comment on Fiedler and Kareev (2006).

Fiedler and Kareev (2006) have claimed that taking a small sample of information (as opposed to a large one) can, in certain specific situations, lead to greater accuracy—beyond that gained by avoiding fatigue or overload. Specifically, they have argued that the propensity of small samples to provide more extreme evidence is sufficient to create an accuracy advantage in situations of high caution and uncertainty. However, a close examination of Fiedler and Kareev's experimental results does not reveal any strong reason to conclude that small samples can cause greater accuracy. We argue that the negative correlation between sample size and accuracy that they reported (found only for the second half of Experiment 1) is also consistent with mental fatigue and that their data in general are consistent with the causal structure opposite to the one they suggest: Rather than small samples causing clear data, early clear data may cause participants to stop sampling. More importantly, Experiment 2 provides unequivocal evidence that large samples result in greater accuracy; Fiedler and Kareev only found a small sample advantage here when they artificially reduced the data set. Finally, we examine the model that Fiedler and Kareev used; they surmised that decision makers operate with a fixed threshold independent of sample size. We discuss evidence for an alternative (better performing) model that incorporates a dynamic threshold that lowers with sample size. We conclude that there is no evidence currently to suggest that humans benefit from taking a small sample, other than as a tactic for avoiding fatigue, overload, and/or opportunity cost—that is, there is no accuracy advantage inherent to small samples. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

嵊泗县贝类生产海域贻贝和环境监测的研究

实验研究了嵊泗三个海域的贻贝中大肠杆菌、菌落总数、铅和镉的含量情况,并对贻贝的生长环境的水质进行了检测。结果表明,抽检的贻贝大肠杆菌、菌落总数符合农业部一类贝类生产养殖区标准。其铅、镉含量也符合《食品中污染物限量》(GB 2762-2012)要求。同时,水质样品铅和镉的含量符合《中华人民共和国渔业水质标准(GB 11607-1989)》的限量要求。     

基于超素数的托普利兹观测矩阵构造方法

观测矩阵在信号压缩感知中十分重要,直接决定信号的重构质量。为保证信号的重构精度,要求观测矩阵具有很强的随机性,但随机矩阵硬件实现非常困难;确定性观测矩阵易于实现,但其重构精度不足。针对观测矩阵对随机性与确定性的双重要求,提出利用超素数产生超长周期的伪随机序列,解决确定性观测矩阵对随机性的要求;结合托普利兹观测矩阵的确定性结构特征,得到一种改进的托普利兹观测矩阵。实验仿真表明:改进的托普利兹观测矩阵与高斯随机观测矩阵和常用托普利兹观测矩阵相比,其信号重构精度得到了很好的改善,且易于硬件实现。     

A fuzzy‐dependent chance multi‐objective programming for water resources planning of a coastal city under fuzzy environment

A fuzzy multi‐objective water resources management model is developed to determine the satisfactory water allocation plan in a coastal city of Northeast China. The imprecise predicted values of parameters are represented by fuzzy numbers, and seven fuzzy objectives of maximizing the possibilities of satisfying the water requirements for six users and total cost less than the expected value are considered. After weighted summation method (WSM) is used to transform the multi‐objective model into a single‐objective model, the satisfactory water allocation plan is efficiently derived according to decision makers' preferences by using a hybrid solution procedure of combining genetic algorithm with fuzzy simulation technique. Results of sensitivity test imply that the interval [0.2, 0.6] of cutting level, surface water and groundwater supplies have the most sensitive influence on results of the model. Moreover, results of discussion demonstrate that the assumption of linearity can be accepted, and membership function of fuzzy number has little influence on results of the model.     

Large Eddy Simulation of Turbulent Reacting Mixing of Liquids in a Coaxial Jet Mixer

Large eddy simulation is used to investigate passive and reactive scalar mixing at high Reynolds Re and Schmidt Sc numbers in order to prove capability of the LES‐SGS micromixing approaches based on the eddy dissipation and DQMOM‐IEM models properly simulating liquid reacting flows. Simulations were performed for a fast neutralization reaction in a confined jet reactor. The mean profiles for passive scalar agree well with measurements. It was shown that the most contribution to the scalar variance is made by large scale motions whereas the contribution of fine scales smaller than typical inertial range scales is negligible. Thus, the existing LES models are capable of predicting the scalar variance at large Sc numbers. The results obtained for reactive transport revealed discrepancies in the determination of micromixing rate and product concentration. A special study was performed to investigate the dynamics of fine structures using locally refined box embedded into global grid. Typical statistical properties of fine structures were reproduced numerically.