EZ型直升机构型更改流程研究

良好的构型控制与更改管理使飞机生产商和开发者们能够处理飞机制造过程中的各种变化,因而成为复杂的飞机设计制造过程中,技术管理工作的最重要部分。通过对EZ型直升机在这方面的先进理念和技术的研究,阐述了EZ型直升机更改管理模式和技术状态管理方法。     

四旋翼飞行器飞行轨迹的仿真研究

设计以四旋翼飞行器为实际对象,针对四旋翼飞行器的多变量、欠驱动等特点,首先对四旋翼飞行器的受力情况和飞行状态做了深入研究,并在此基础上完成了四旋翼飞行器的力学建模和运动学建模;其次将得到的模型应用到MATLAB仿真中,分别对角度和位置回路的PID控制算法和积分分离PID控制算法进行了仿真,验证了控制算法的可行性。     

直升机尾桨涡环状态研究

介绍了直升机尾桨涡环状态的现象,分析比较了三种涡环判据的应用特点。针对某型直升机尾桨涡环状态,计算了其侧飞临界速度和临界悬停回转角速度。描述了实际飞行中直升机进入尾桨涡环状态的现象,提出了改出尾桨涡环状态的方法。     

转运点运输皮带影响下的诱导气流研究

转运点物料输送过程会产生复杂的气流,其影响气流规律的因素较多。微粒在自由下落过程中会携带环境空气进入料流间隙,并随料流运动,其料流又对周围空气存在一定的拽曳作用,导致周围空气随物料运动,当物料下落并撞击底部皮带时,其夹带的空气从料流中析出,分散在空间中形成絮乱的复杂气流,而紊乱气流的运动使得吸附在煤块上的细小粉尘颗粒弥散到周围空气中造成污染。     

救援装备

米-26直升机 米-26是当今世界上最重的直升机。其旋翼为八片矩形桨叶,尾桨为五片桨叶,起落架为不可收放的前三点式。它的动力装置是两台乌克兰扎波罗日“进步”机器制造设计局的D—136涡轮发动机,单台功率为7460千瓦。米-26的空重为28200公斤,最大起飞重量56000公斤。     

浅析消防救援直升机水炮系统

每年全世界都有不计其数的人因为高楼失火而丧生，摩天大楼内部只装有简单的设备用以对抗火灾，而这只是解决消防问题手段的一小部分，地面消防支援也是非常有限的。直升机消防水炮是解决高楼消防的一种新的途径，在国外也尚属全新的理念，但这却是很多人对直升机是否可以用于高楼消防的大胆设想成为了现实。为高层建筑消防灭火而专门设计的直升机安装水/泡沫输送系统。该系统通过超出旋翼片长度的喷射杆进行水流及泡沫的输送，从而达到灭火的目的。     

由“蝴蝶效应“所想到的

1963年,美国麻省理工学院气象学家洛仑兹根据一次科学计算的结果提出了“蝴蝶效应“.“蝴蝶效应“是指在南美洲亚马逊河流域热带雨林中,一只蝴蝶漫不经心地拍动几下翅膀,可能在两周后引起美国得克萨斯州一场灾难性的风暴.其原因在于:蝴蝶翅膀的运动导致周围的空气系统发生变化,并引起微弱气流的产生,而微弱气流的产生又会引起它四周空气或其他系统产生相应的变化,由此引起连锁反应,最终导致其他系统的极大变化.……     

象四十岁男人那样“沉”下来

最近我发现,周围有好几个四十岁左右的“老男人”陆续收山,工作之外开始踏踏实实地享受家庭生活。他们的生活状态发生了很大变化,人更“沉”了也更“静”了,随之,他们做事情也变得比以前从容和靠谱了不少。     

城市环境中四旋翼飞行器的安全操控方法

四旋翼飞行器目前在城市中普遍应用,但在城市环境中操控四旋翼飞行器,必须严格保证其飞行安全。文章阐述了关于四旋翼飞行器操控问题的需求背景和飞行器系统的组成与飞行原理,通过分析四旋翼飞行器的两种操控方式,从飞行前航路规划、飞行中实时监控、紧急情况人工切换三个方面提出了面向城市环境的四旋翼飞行器的安全操控要求。     

浅谈AS350B2（小松鼠）直升机在航空护林中的应用

AS350B2（小松鼠）直升机属于单发涡轮轴滑橇式轻型直升机。该机采用了一台透博梅卡阿赫耶1D1发动机，机体长10.93米、高3.14米、旋翼直径10.69米，理论净升限6096米，发动机额定功率750千瓦，空机重1224公斤，最大起飞重量2250公斤，带外挂最大起飞重量2500公斤，最大外挂重量1160公斤，最小空勤组1人，载客量1名飞行员＋5名乘客（标准型），外挂吊载750公斤，绞车钢索载荷136公斤、巡航速度220公里/小时、燃油量426公斤，续航时间3小时，航程660公里。     

A multidisciplinary assessment of waste paper recovery from an institutional source

A multidisciplinary study of waste paper recovery from a complex of state government office buildings was undertaken for the purpose of developing, evaluating and recommending cost-reducing modifications in the present operations. Previous research on resource recovery has focused on either the total mixed municipal stream or specific residual materials within that stream. Little work has investigated the recycling potential of wastes from a particular institution such as state government which generates a considerable volume of waste paper. A major thrust of this research was a survey of the office workers and custodians who must participate in a waste paper recycling program. The economic viability of waste paper recovery programs is highly contingent on voluntary willingness of office workers to sort reclaimable residuals at the point of discard. This study demonstrated that office workers were receptive to recycling program, but that mere receptivity could not guarantee a successful program unless the participants were adequately advised on how to make distinctions between salvageable and nonsalvageable materials. Reluctance to support any administrative role change was found among custodial workers. This study also illustrated the financial advantages of manual separation at the source, as well as the impact of central storage and other modifications on the economics of the present system.     

Research and theory on high‐performance work systems: progressing the high‐involvement stream

The notion of a high‐performance work system (HPWS) constitutes a claim that there exists a system of work practices for core workers in an organisation that leads in some way to superior performance. In this article, we dissect this fuzzy notion and examine its companion terminology: high‐involvement work systems and high‐commitment management. We argue that a focus on the high‐involvement stream usefully grounds HPWS studies in an important area of workplace change in the current context and takes us away from eclectic and contentious selections of ‘best practices’. We review research models and findings in this stream. The path to better research lies in examining the underpinning processes experienced by workers when management seeks to pursue high‐involvement systems, and charting their links to employee and operational outcomes.     

Making it work in free agent work: The coping practices of Swedish freelance journalists

Studies of post-industrial work have shown how workers are increasingly shouldering the risk of and the responsibility for social protection, work shortages, professional training, and securing a stream of continuous incoming work. This study of Swedish freelance journalists examines how these free agents cope with a situation whereby the need exists to actively bear the full responsibility for attracting and contracting, producing, and billing their work as journalists. The empirical material shows how freelancers engage in various coping practices to secure both sufficient amounts of work and the accompanying economic compensation. Freelancers who “make it work” are often those managing to embed themselves in long-standing relationships with clients and colleagues, thus ensuring a long-term work horizon and a steady income. Even so, the inherent “responsibilization” of contemporary work is amplified and intensified by the freelance work mode. This study makes two contributions: Firstly, it provides knowledge of free agent work in a Swedish context, a national setting that is often presumed to be a “role model” for good working conditions. Secondly, it highlights the specifics of managing work that entails a continuous stream of sequential and parallel assignments of limited duration and the ongoing “employment management work” this entails as regards making sure assignments keep “coming in”.     

Income taxes and the destination of movers to multistate MSAs

We examine how differences in state income tax rates, as well as other state and local taxes and public service expenditures, influence the choice of state of residence for households (federal tax filers) moving into multistate metropolitan areas (MSAs) using data from the IRS on the migration of taxpayers. MSAs that are on borders provide a spatial discontinuity—discrete differences in state tax rates within a single labor market. These MSAs allow residents to live in one state and work in another state. We find that differences in state income tax rates have a significant impact on the relative rate of migration to the states within an MSA. However, contrary to what would be expected, this impact is only significant in MSAs in which the filing state is based on employment (states without reciprocity) and not for those states in which the filing state is the state of residence (states with reciprocity). In MSAs where states do not have reciprocity agreements, a difference of ten percent in tax rates leads to a 4.1 percent difference in the relative rate of incoming taxpayers. Analogously, we find that a ten percent difference in state tax rates in these MSAs results in a 3.3 percent difference in the rate of tax base inflow (AGI). Our results suggest that one reason that differences in state income taxes appear to have more impact in multistate MSAs without reciprocity is that only relatively large differences in state income tax rates have any impact on migration and these differences are much more pronounced in MSAs without reciprocity.     

The model employment termination act: Provisions and discussion

Recently, the National Conference of Commissioners on Uniform State Laws completed a drafting of the Model Employment Termination Act (META). The goal of this suggested state legislation is to end the patchwork of state-defined protections offered to employees who are terminated in at-will work environments. If META provisions are adopted there will be a substantial change in both the protection offered employees and the litigation of wrongful discharge claims within the adopting state. This article presents the changes proposed by META and discusses these changes and their potential implications for employers and employees.     

电动机综合控制技术

本文的电动机控制技术,是以"变相电阻"为基础,以控制电动机转子电流为核心,包括电动机的启动、调速技术。通过斩波技术,实现转子阻抗的变化,控制转子电流。     

How do experienced traders respond to inflows of inexperienced traders? An experimental analysis

We conducted asset market experiments where one experienced subject interacts with five inexperienced subjects to investigate how experienced subjects change their price forecasts and trading behavior when faced with strategic uncertainty caused by inflows of inexperienced subjects. Only half the experienced subjects initially forecasted prices deviating more from the fundamental values in the market with five inexperienced subjects than in the final round of the experiment in which they had previously participated. Furthermore, the majority of our experienced subjects did not change their trading behavior. Many experienced subjects act as price stabilizers when the inflow of inexperienced subjects is not associated with other changes in market conditions.     

郭沟煤矿勘探区水文地质条件研究

郭沟煤矿勘探区面积15.32km2,涌水量34.07m3/h,与周边面积接近的矿区相比,涌水量小了10-30倍,文章研究了郭沟勘探区区域水文地质条件、勘探区水文地质条件以及勘探区充水因素,分析了勘探区涌水量的组成、来源以及比周边煤田小的原因,确定了勘探区正常涌水量和水文地质勘查类型。勘探区水文地质条件的研究对未来矿山设计、开发、煤矿安全生产以及相邻矿区水文地质工作具有指导和借鉴意义。     

Inference on stochastic time-varying coefficient models

Recently, there has been considerable work on stochastic time-varying coefficient models as vehicles for modelling structural change in the macroeconomy with a focus on the estimation of the unobserved paths of random coefficient processes. The dominant estimation methods, in this context, are based on various filters, such as the Kalman filter, that are applicable when the models are cast in state space representations. This paper introduces a new class of autoregressive bounded processes that decompose a time series into a persistent random attractor, a time varying autoregressive component, and martingale difference errors. The paper examines, rigorously, alternative kernel based, nonparametric estimation approaches for such models and derives their basic properties. These estimators have long been studied in the context of deterministic structural change, but their use in the presence of stochastic time variation is novel. The proposed inference methods have desirable properties such as consistency and asymptotic normality and allow a tractable studentization. In extensive Monte Carlo and empirical studies, we find that the methods exhibit very good small sample properties and can shed light on important empirical issues such as the evolution of inflation persistence and the purchasing power parity (PPP) hypothesis.