Energy-Efficient Trajectories of Unmanned Aerial Vehicles Flying through Thermals

This study presents optimal energy-efficient flight trajectories of a generic unmanned aerial vehicle (UAV) flying through a vertical moving thermal cell. A two-dimensional point-mass model of a jet-engined UAV in the vertical plane is used. UAV equations of motion and the thermal wind expression are normalized for numerical efficiency and four fundamental parameters are identified. UAV flights through a thermal cell are formulated as nonlinear optimal control problems that minimize the average thrust per unit time, subject to UAV performance constraints and periodic flight boundary conditions. These problems are converted into parameter optimizations and solved numerically. Fuel efficiencies of these optimal trajectories are compared with those of reference optimal flights in the lack of thermal winds. Both constant thrust and variable thrust solutions are obtained. Two patterns of optimal flights through thermals are identified, and their characteristics are analyzed. Both patterns of optimal flights are also explained from an energy maximization point of view. Effects of the fundamental parameters on optimal UAV flights are examined. Results suggest that significant improvements in UAV fuel consumption are possible by taking advantage of thermal energies.     

Drug-associated hemorrhagic enteritis

Drug-associated hemorrhagic colitis are divided into antibiotic associated hemorrhagic colitis (AAHC) and other drug associated hemorrhagic colitis. AAHC are mainly caused by oral usage of Ampicillin and its derivatives (85%). Initially AAHC are believed to be caused by Klebsiella oxytoca overgrowth. However, these organisum has no exotoxin like Clostridium difficile and pathogenesis of AAHC are still unresolved. Typical AAHC are diagnosed by colonoscopy with diffuse hemorrhage and edema mainly found in descending colon and transverse colon. NSAIDs are also the cause of hemorrhagic colitis like AAHC. Mephenamic acid are famous for this complication. Diarrhea is one of the main complication of oral 5-fluorouracil administration and even causes hemorrhagic colitis. Its histology are characteristic in gland atrophy. Gold colitis are reported 36 cases in rheumatoid arthritis patients. Exact mechanism of bleeding are not understood. NSAIDs may cause collagenous colitis and or lymphocytic colitis in RA patients. Other rare hemorrhagic colitis are associated with azathioprine, methyl dopa, interferon alfa etc. NSAIDs and anticoagulants are well known drugs for complication of GI bleeding making hemorrhagic enteritis.     

Statistical theory of the hydrogen-induced phase decomposition of an amorphous zirconium-palladium alloy with the formation of metal hydrides. Hydrogen solubility in phases

A statistical theory is developed for the decomposition of an amorphous zirconium-palladium alloy in a hydrogen atmosphere with the formation of metal hydrides. The free energies of the phases are calculated, and equations for the equilibrium states of the phases are derived. The phase-transformation temperatures are determined, and their dependences on the system composition are obtained. The temperature dependences of the hydrogen solubilities in the phases are found, and the appearance of the inflection points or jumps at the phase-transformation points, which are experimentally observed as inflections in the dependences, is grounded. Hydrogen solubility isotherms are calculated, and the possibility of a hysteresis effect is revealed.     

赣南钨矿山资源状况调查与思考

通过赣南钨矿山资源调查,反映钨矿山资源状况不容乐观。据地质报告中统计,赣南累计探明WO3储量149.98万t,其中上平衡表113.67万t,而保有储量仅有46.7万t;国有钨矿山保有储量26.4万t,可利用的储量10.4万t,可服务年限大都在10a以下。因此,建议尽快对赣南的国有钨矿山开展新一轮的地质找矿,寻找新的接替基地,控制钨矿产量,对尾砂综合回收和利用。     

客运专线用100米钢轨矫直断裂原因分析

 客运专线用100米60kg/m重轨在焊轨厂拼焊后,当四面矫直时发生断裂。采用光学显微镜及扫描电镜（TEM）等方法对钢轨矫直时断裂原因进行了分析和研究。结果表明：钢轨断裂是由于距钢轨端部约100mm轨底边缘处存在凸台缺陷,此凸台在钢轨拼焊后进行除瘤时除瘤刀将其铲平,致使钢轨产生冷裂纹,进而在矫直时断裂。通过控制万能精轧上下辊的辊径差以及调整轧制线高度等方面,使钢轨出轧机时尽量保持平直,避免上翘或扣头,从而消除凸台缺陷的产生。     

Optimum Design of Welded Steel Plate Girder Bridges Using a Genetic Algorithm with Elitism

The genetic algorithm (GA) is a general optimization technique that has some unique features that are especially suitable for structural engineering problems. This work uses a simple GA with elitism to find the optimum design of welded steel plate girder bridges. The objectives are to minimize the weight and the cost of the girders. Two types of plate-girder bridges are studied: a single-span bridge and a two-equal-span continuous bridge. Bridges with various span lengths, in increments of 20?ft, are investigated; results are tabulated, parametric studies are made, and meaningful conclusions are drawn.     

Intracellular bacteria in protozoa

Intracellular bacteria in humans are typically detrimental, and such infections are regarded by the patients as accidental and abnormal. In protozoa it seems obvious that many bacteria have coevolved with their hosts and are well adapted to the intracellular way of life. Manifold interactions between hosts and intracellular bacteria are found, and examples of antibacterial resistance of unknown mechanisms are observed. The wide diversity of intracellular bacteria in protozoa has become particularly obvious since they have begun to be classified by molecular techniques. Some of the bacteria are closely related to pathogens; others are responsible for the production of toxins.     

Models of helping and coping.

Draws a distinction between attribution of responsibility for a problem and attribution of responsibility for a solution. Four general helping models are derived. In the "moral" model, actors are held responsible for both problems and solutions and are believed to need only proper motivation. In the compensatory model, people are responsible only for solutions and are believed to need power. Individuals in the medical model are responsible for neither problems nor solutions and are thought to need treatment. In the enlightenment model, actors are responsible for problems but are unable or unwilling to provide solutions; they need discipline. It is maintained that each set of assumptions has characteristic consequences for the competence, status, and well-being of actors and that the wrong choice of model in a situation will undermine effective helping and coping. Competing models of responsibility in education, psychotherapy, law, and welfare are described, and research on attribution of responsibility is recommended as a way of addressing problems of both theoretical and social significance. (128 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

QC22—20—25／400燃气锅炉存在问题与技术改造

燃气锅炉中普遍使用的多管式燃烧器,在燃用炼铁高工气时,会产生积灰堵塞、火焰中心后移而导致的过热蒸汽温度偏高等一系列问题,分析了产生这些问题的原因,在不改动锅炉结构及受压元件的前提下,对燃烧器做了改造,比较了改造前后的运行参数,并总结了成功的经验及改造中的不足。     

矿产资源定价方法的实证研究

文中分析了资源－环境－经济一体化核算的研究现状及存在的问题,界定了矿产资源核算的内涵及其对象,论述了矿产资源定价的理论基础,探讨了矿产资源的各种定价方法及其优缺点,适用范围,建立相应的估价模型,并进行了实证分析,这项研究对我国的资源－－环境－经济一体化核算的理论研究与实践进展具有重要的理论意义和现实意义。     

Arachnoid cysts on computed tomography

The appearances of arachnoid cysts on computed tomography are presented. They are well defined lesions with the same density as cerebrospimal fluid and are not contrast enhanced. Superficial lesions are biconvex or semicircular and may have a characteristic straight inner margin. Deep lesions and cysts between the cerebellar hemispheres are spherical and some may be difficult to differentiate from cystic neoplasms. The etiology and clinical manifestations of arachnoid cysts are also briefly discussed.     

甘肃金山矿区金矿床成矿构造类型及成矿机制探讨

金山矿区有3个金矿床,矿体产于褶皱翼部或核部,构造控矿作用十分明显,对矿(化)体空间分布、矿化富集等均有明显的控制作用,主要有3种类型:层间断裂裂隙构造、切层断裂裂隙构造、成矿期后的断层裂隙构造。层间断裂构造控制着以充填地质作用形成的石英脉型矿体;层间断裂构造两侧并与之平行的层间裂隙构造、切层断裂裂隙构造控制着以交代地质作用形成的微细粒浸染型矿体;两组断裂裂隙交叉部位是成矿的有利部位;建立的构造控矿模式表明,矿区控矿构造由褶皱构造与岩体侵位构造共同控制。     

推钢式加热炉的技术改造及效果

介绍了包钢特钢分公司推钢式加热炉技术改造的情况,对加热炉存在的问题进行了分析,提出了改进措施,经过技术改造提高加热炉的能力,降低了煤气消耗,取得了较好的经济效益。     

HOT PRESSING OF CERAMIC POWDERS

Abstract

The processes involved in the production of dense ceramics from powder materials by the simultaneous effect of pressure and heat at temperatures above 1500°C are outlined. The factors leading to the choice of this method of fabrication, and the general principles involved in hot pressing, are first dealt with, and the advantages and disadvantages of the process are then discussed. Current techniques are described and their limitations considered. Examples of typical applications are given, and possible lines of future development are indicated.     

On myositis ossificans localisata and its operative treatment (author''s transl)

The methods of performing keratomileusis and keratophakia are described. The principles of the calculations are outlined. Results and complications are enumerated. The indications for the methods are discussed.     

Computer simulation of fatty acids

Fatty acids modified by sulfhydric collectors are investigated. Three-dimensional molecular models are constructed for these acids and the main computer parameters of the total steric energy are determined. Based on the computer design, new reagents are suggested and molecular models are constructed and the total steric energy is calculated for them.     

井子坳钨银铅锌矿成矿地质特征及找矿方向

江西省上犹县井子坳钨银多金属矿区是20世纪90年代详查评价确定的大型层状矽卡岩型钨银铅锌矿床,其储量:WO3大于5万t、Ag大于1000t,Pb+Zn大于30万t,该矿床的特征和成矿特点对江西南部和近邻地区的找矿均有指导与示范意义。笔者通过矿床地质特征和成矿地质规律的综合分析,对该矿床的成因及控矿因素进行了初步总结,并提出了外围及邻近地区的找矿方向。     

钨纳米线的制备与应用

综述了钨纳米线的最新研究进展,详细地介绍了数种钨纳米线的制备技术和这种新型纳米材料潜在的巨大应用价值,提出了目前报道的制备方法中存在的几个问题,并展望了未来的发展趋势。     

曼型气柜支柱的安装方法

通过对曼型气柜关键部位之一的基柱的安装和找正过程的分析，表明基柱安装前对基础进行预处理、安装时测量跟踪找正、安装后定位加固，是保证基柱安装精度的三个重要步骤。