An experimental and numerical study of hunting in thermostatic-expansion-valve-controlled evaporators

The dynamic behaviour of a thermostatic-expansion–valve (TEV)-controlled dry-evaporator is studied experimentally and numerically. Although the linear model of the TEV together with the distributed model of the evaporator is able to predict the stable dynamic response of the system adequately, it fails to reproduce the hunting behaviour that is observed under certain operating conditions. A scrutiny of the experimental data reveals the possible existence of hysteresis in the system. The distributed model including the experimentally determined input-output characteristics of the TEV is able to reproduce the main features of the hunting oscillations well. The amplitude and frequency of these oscillations depend on the static superheat setting, the heat load of the evaporator and the time constant of the TEV bulb.     

Extracting TSK-type Neuro-Fuzzy model using the Hunting search algorithm

This paper proposes a Takagi-Sugeno-Kang (TSK) type Neuro-Fuzzy model tuned by a novel metaheuristic optimization algorithm called Hunting Search (HuS). The HuS algorithm is derived based on a model of group hunting of animals such as lions, wolves, and dolphins when looking for a prey. In this study, the structure and parameters of the fuzzy model are encoded into a particle. Thus, the optimal structure and parameters are achieved simultaneously. The proposed method was demonstrated through modeling and control problems, and the results have been compared with other optimization techniques. The comparisons indicate that the proposed method represents a powerful search approach and an effective optimization technique as it can extract the accurate TSK fuzzy model with an appropriate number of rules.     

Hunters are a fundamental component of northern bobwhite quail conservation

Hunters have been a fundamental component of northern bobwhite quail conservation for most of the past century. Bobwhite quail hunters funded the first modern comprehensive life history study of a wild vertebrate in the 1920s to understand causes responsible for population declines. This investigation identified a causal link between frequent applications of prescribed fire and persistence of bobwhite quail populations in the Southeastern United States, and provided the foundation for contemporary fire ecology science. Since then, hunters in the Southeastern and Midwestern United States have funded numerous other bobwhite quail research and conservation efforts. Research and conservation efforts funded by quail hunters in Texas continue to be especially notable. Non-governmental organizations, and academia, as well as state and federal wildlife agencies have been the conduits for efforts to sustain bobwhite quail populations because predominant land uses no longer support bobwhite quail.     

Browsing functions in three-dimensional space for digital libraries

In order to get useful information from various kinds of information sources, we first apply a searching process with query statements to retrieve candidate data objects (called a hunting process in this paper) and then apply a browsing process to check the properties of each object in detail by visualizing candidates. In traditional information retrieval systems, the hunting process determines the quality of the result, since there are only a few candidates left for the browsing process. In order to retrieve data from widely distributed digital libraries, the browsing process becomes very important, since the properties of data sources are not known in advance. After getting data from various information sources, a user checks the properties of data in detail using the browsing process. The result can be used to improve the hunting process or for selecting more appropriate visualization parameters. Visualization relationships among data are very important, but will become too time-consuming if the amount of data in the candidate set is large, for example, over one hundred objects. One of the important problems in handling information retrieval from a digital library is to create efficient and powerful visualization mechanisms for the browsing process. One promising way to solve the visualization problem is to map each candidate data object into a location in three-dimensional (3D) space using a proper distance definition. In this paper, we will introduce the functions and organization of a system having a browsing navigator to achieve an efficient browsing process in 3D information search space. This browsing navigator has the following major functions: ?1. Selection of features which determine the distance for visualization, in order to generate a uniform distribution of candidate data objects in the resulting space. ?2. Calculation of the location of the data objects in 2D space using the selected features. ?3. Construction of 3D browsing space by combining 2D spaces, in order to find the required data objects easily. ?4. Generation of the oblique views of 3D browsing space and data objects by reducing the overlap of data objects in order to make navigation easy for the user in 3D space. ?Examples of this browsing navigator applied to book data are shown. Received: 15 December 1997 / Revised: June 1999     

铁路货车横向非线性动态行为的理论与试验研究

运用车辆－轨道耦合动力学理论,建立三大件式转向架货车与轨道结构耦合动力学模型,详细考虑货车系统非线性特性,包括轮轨接触非线性、轴箱间隙非线性、楔块干摩擦非线性及转向架抗菱刚度非线性等。以我国广泛运用的转8A转向架货车为例,从理论上分析货车的横向非线性运动稳定性。结果表明,空车蛇行失稳临界速度仅为78 km/h。实车运行试验的结果表明,当该型货车空车以75 km/h速度在直线轨道上运行时,车体表现出剧烈的横向蛇行运动现象,蛇行运动主频为2.69 Hz,蛇行波长为7.745 m。     

压力容器补强圈气密性试验的探讨

介绍了压力容器补强圈和检漏孔结构及其制造技术要求,分析了补强圈焊接结构对焊接质量和补强圈气密性试验的影响,对补强圈气密性试验的方法、要求和存在的普遍问题进行了分析和总结,并提出了相应的解决措施和建议。     

The North American approach to waterfowl management: synergy of hunting and habitat conservation

Hunters have been central to waterfowl management in North America over the past century. Numerous partnerships among government agencies, non-government organizations and private individuals form the core of conservation endeavours for migratory ducks, geese and swans and their diverse habitats. As a consequence of these efforts and the resilience of waterfowl populations, these species have fared better than most guilds of migratory birds. Threats to remaining habitats and the waning connections of people to wild things and wild places comprise the most serious challenges to sustaining this system.     

Hunting and Landscape in Denmark: Farmers' Management of Hunting Rights and Landscape Changes

Hunting represents an important activity in Danish rural landscapes. In this paper, we analyse recent developments in farmers' management of the right to hunt and associated landscape activities in three agricultural regions based on surveys from 1995/96 and 2008. The results show that the total area on which farmers hunt has increased, especially the area on which the owner is the hunter. This indicates that interest in hunting is increasing, and the interest for hunting may play an increasing role as a landscape activity and as a motive to become a farm property owner. Concerning landscape management, non-hunters, surprisingly, seem to have a more game-friendly management practice than hunters. On the other hand, hunters own farms with forests and/or farms located in areas of high landscape heterogeneity more often than non-hunters. Local hunting associations play an interesting role in relation to non-owners' accessibility to hunting and such associations may play a significant role in the future management of the landscape as a commons.     

100 Year City (Maribor): The Virtual Concourse Reframed

For interactivity, the virtual world so often relies on a physical component, but how might virtual spaces be made more tangible as spatial environments for exchange? Under the direction of architect and RMIT University professor Tom Kovac, in 2012 the 100 Year City project rose to this challenge as part of the Maribor European Capital of Culture programme. Here, Guest-Editor and Deputy Curator of the project, Fleur Watson , describes how this ‘super studio’ incites cross-disciplinary exchange and the sharing of progressive design ideas for sustainable blueprints for our cities. It is an initiative that is to be continued under Kovac's directorship with the 100 Year City-themed Malaysian Biennale in the summer of 2015.     

铁道车辆含故障参数的非线性动力学模型

随着铁路高速重载的提出,货车转向架的非线性动力学问题日益突出,货车系统动力学性能和安全运行已是亟需研究的课题。本文分析三大件转向架容易损坏并发生故障的关键部件的故障形式,重点分析了二系悬挂减振装置中的磨耗故障的发生。建立了含有故障参数的39自由度货车车辆非线性动力学模型。通过对其进行大量的数值仿真,考察系统动力学响应和相应故障参数变化之间的关系,以此为基础探讨研究故障机理的新思路。