井下液气分离器分离原理及结构改进

液气分离器就是充分利用电泵机组的高转速、气体和液体之间悬殊的密度差异进行液气离心分离。经过多年的发展,在传统的液气分离器结构基础上又出现了许多新的设计和改进,大大提高了液气分离器的分离效果。文章重点论述了液气分离器的分离原理和结构上的改进之处。     

Prevalence of asthma and asthma-like symptoms in three French cities

BACKGROUND: This study is part of the European Community Respiratory Health Survey (ECRHS), which uses a common methodology in different areas throughout the world. This paper describes the prevalences of reported asthma, asthma-like symptoms and nasal allergies, their relationships to age group and sex, and the relationships of asthma-like symptoms to current asthma, in the general population aged 20-44 years of three French urban areas. METHODS: The study population of 2804 subjects in Grenoble, 3774 in Montpellier and 3152 in Paris (18th district), randomly selected from electoral rolls, answered a postal questionnaire (stage I of ECRHS). The response rates were 77.8%, 68.6% and 74.4%, respectively. RESULTS: The prevalences were approximately 14% for wheezing, 16% for chest tightness and 4.5% for nocturnal shortness of breath in the three areas. Asthma attacks in the last 12 months were reported by 2.7% of subjects in Grenoble, 3.5% of subjects in Montpellier and 4.0% of subjects in Paris (P = 0.02). For nasal allergies, the prevalences were 28.0%, 34.3% and 30.8%, respectively (P < 0.001). Asthma was inversely correlated to age (higher prevalence in the youngest) but was not related to sex. Neither age distribution nor sex ratio explained the differences between areas. Among the asthma-like symptoms, wheezing and nocturnal shortness of breath correlated strongly with asthma, chest tightness correlated moderately and nocturnal coughing correlated poorly. CONCLUSION: The prevalences observed were higher than expected from previous comparable French studies in young adults. These results are consistent with the hypothesis of a recent increase of asthma and allergies.     

网格生成方法在APFSDS及弹托干扰流场计算中的应用

介绍APFSDS及弹托干扰流场数值模拟中的网格生成方法及其应用。利用等比数列网格生成技术，三维弧长生成技术以及拼接技术生成计算网格。该方法具有简明、快捷的特点。在临近物面的地方具有较好的贴体性和正交性。在计算脱壳穿甲弹和弹托之间的干扰时，将弹托简化为带圆弧的楔形块，计算结果比较令人满意。     

中小城镇住宅消防设施现状及建设管理探索

通过对西部某小城市的住宅消防设施建设和管理现状的调查 ,反映了占西部绝大部分城市面积的中小城镇的住宅消防设施十分令人担忧的现状 ,分析了造成这一现状的原因 ,提出了解决这一问题的建设管理思路     

基金最佳使用计划

本文给出了基金存款策略的数学模型.对于基金M使用n年的情况而言,首先把M分成n份,其中第i(1≤i≤n)份存款xi存期为i年,那么只有当第i(i ≤n-1)份资金按最佳存款策略存款到期后的本息和等于当年的奖学金数,并且第n份资金按最佳存款策略存款n年后的本息和等于原基金M与当年的奖学金数之和时,每年发放的奖学金才能达到最多.通过求解此模型,我们得到了基金的最佳存款策略,并求出了在n=10年,M=5000万元的情况下,基金的最佳使用方案.在可存款也可购买国库券时,采取一种转化方法,将国库券购买情况转化为相应年期的定期存款,结合问题(一)即可求得在n=10年,M=5000万元的情况下,基金的最佳使用方案;在第三年校庆时奖学金数额比其它年度多20%的问题的分析方法和模型的解决方法与前相同.     

具有多重焦点的波带透镜的设计

本文提出了一种新型的具有多重焦点的波带透镜的概念及其设计方法。可提供某些特定的光场分布,而且具有性能稳定、微型化和可实际制作等特点。     

Genetic algorithm hybridized with multilayer perceptron to have an economical slope stability design

The present work aimed to evaluate and optimize the design of an artificial neural network (ANN) combined with an optimization algorithm of genetic algorithm (GA) for the calculation of slope stability safety factors (SF) in a pure cohesive slope. To make datasets of training and testing for the developed predictive models, 630 finite element limit equilibrium (FELE) analyses were performed. Similar to many artificial intelligence-based solutions, the database was involved in 189 testing datasets (e.g., 30% of the entire database) and 441 training datasets; for example, a range of 70% of the total database. Moreover, variables of multilayer perceptron (MLP) algorithm (for example, number of nodes in any hidden layer) and the algorithm of GA like population size was optimized by utilizing a series of trial and error process. The parameters in input, which were used in the analysis, consist of slope angle (β), setback distance ratio (b/B), applied stresses on the slope (F_y) and undrained shear strength of the cohesive soil (C_u) where the output was taken SF. The obtained network outputs for both datasets from MLP and GA-MLP models are evaluated according to many statistical indices. A total of 72 MLP trial and error (e.g., parameter study) the optimal architecture of 4 × 8 × 1 were determined for the MLP structure. Both proposed techniques result in a proper performance; however, according to the statistical indices, the GA–MLP model can somewhat accomplish the least mean square error (MSE) when compared to MLP. In an optimized GA–MLP network, coefficient of determination (R²) and root mean square error (RMSE) values of (0.975, and 0.097) and (0.969, and 0.107) were found, respectively, to both of the normalized training and testing datasets.

     

Insight into an unsupervised two-step sparse transfer learning algorithm for speech diagnosis of Parkinson’s disease

Neural Computing and Applications - Speech diagnosis of Parkinson’s disease (PD) as a non-invasive and simple diagnosis method is particularly worth exploring. However, the number of samples...     

MicroPort: A general simulation platform for seaport container terminals

Seaport container terminals are essential nodes in sea cargo transportation networks. As such, the operational efficiency of container terminals in handling containers passing through them plays a critical role in a globalized world economy. Many models and algorithms have been developed to address various decision problems in container terminals to help improve operational efficiency. These decision support tools are usually used separately for specific purposes. However, the problems they are trying to tackle are often interrelated. Therefore, in this regard, an evaluation tool which can capture as many operational conditions as possible for different decision problems is necessary. This paper introduces a general simulation platform, named MicroPort, which aims to provide an integrated and flexible modeling system for evaluating the operational capability and efficiency of different designs of seaport container terminals. The software structure of MicroPort comprises three programming layers: (1) the Functions layer; (2) the Applications layer; and (3) the Extensions layer. Different layers are bound by Application Programming Interfaces (APIs). Basic functions built in the Functions layer support the Applications layer in which major operation processes can be modeled by an agent-based method. External modules and decision support tools in the Extensions layer then use APIs to adjust the system to produce suitable simulation models for specific purposes.