回转头技术在表面贴装设备中的应用

当今的回转头式贴装设备能够以相对低廉的价格 ,提供高速度和准确的贴装 ,以及先进的识别操作。     

蒙山景区生态旅游与可持续发展初探

本文从景观设计的角度,阐述了蒙山风景名胜区生态旅游的发展,分析了蒙山风景名胜区发展生态旅游的有利条件和存在的问题,并在此基础上提出生态旅游可持续发展的对策与建议。     

喷射器内胶液流动数值仿真

胶液喷射技术现广泛应用于表面贴装工艺领域。在流固耦合仿真中,对流体动边界的处理是一个难点。利用ANSYS流固耦合作用工具FSI及任意拉格朗日欧拉法对胶液喷射器内胶液流动过程进行了研究。得到喷针运动下胶液喷射器内胶液的压力及速度分布,证明了该方法的有效性,并得出喷针运动直接影响胶液喷射技术实现的结论。     

地球物理勘探联合反演在六盘山盆地的应用

在六盘山盆地进行重力、电法和地震综合勘探的基础上,应用地球物理联合反演方法研究和解决盆山接触关系、断层分布、深部目的层分布和有利构造圈闭特征等问题,为油气勘探部署提供科学依据。     

浅析福清黄檗山万福寺的营建现状

福清黄檗山万福寺作为日本黄檗宗的祖庭,具有重要的历史价值。通过对福清黄檗山万福寺营建现状的调查,有助于更好地促进福建佛教建筑的保护与研究工作,同时对中日交流史的考证也有一定的积极意义。     

浅谈建设美丽旅游景区与旅游产业转型升级问题与措施

分析旅游产业转型升级,自身升级是重点,旅游产品升级是根本,旅游品牌是旅游景区和城市无形资产浓缩,以厦门市北辰山省级风景区创建国家4A级景区为案例,浅谈建设美丽旅游景区与旅游产业转型升级问题和措施,应注重发展模式,注重规划设计,注重优化建设,创新施工管理,根据国家工程建设及4A级景区规范标准,合理规划设计,结合景区实际,创新景区建设施工管理,完善基础配套设施,打造独具特色国家核心品牌,提升旅游品质,最大限度满足旅游需要,提升城市品牌,推进旅游战略新兴产业升级发展,促进经济社会转型升级,建设美丽厦门,直至美丽中国。     

Application of the Stream Evolution Model to a Volcanically Disturbed River: The North Fork Toutle River,Washington State,USA

In this study, a recently revised version of the channel evolution model, named the Stream Evolution Model (SEM), was applied to the upper North Fork Toutle River disrupted by the deposition of a 2.5‐km³ debris avalanche during the catastrophic eruption of Mount St. Helens in 1980. The results show that, in the first few years following the eruption, upstream channel reaches generally incised, evolving in SEM Stage 4 (i.e. degradation and widening), while downstream reaches aggraded, evolving in Stage 5 (i.e. aggradation and widening). However, starting in the late‐1980s, this simple pattern was disrupted by incision in the downstream reaches, which seemed to propagate upstream. Since the 1990s, lateral channel adjustments have become predominant as rates of vertical adjustment have slowed and river valley top widths relaxed to asymptotic values. Spatial and temporal sequences of channel evolution have tended to follow the sequences of stages expected according to the SEM, although these sequences have been frequently disrupted by renewed incision, secondary cycles of adjustment and the impacts of local geologic, geomorphic and hydraulic conditions. Within the quasi‐full SEM cycles, stages 4 and 5 were sometimes repeated, while stage 6 (quasi‐equilibrium) was sometimes omitted, and stage 8 (anabranching) only occurred in the downstream braided/anabranching reaches. According to the SEM, degradation, widening and lateral activity (stages 4 and 7) are forecast to continue until transverse valley profiles and channel planforms stabilize and floodplain and terrace surfaces are fully colonized by vegetation. Copyright © 2017 John Wiley & Sons, Ltd.     

芒特艾萨矿业公司希尔顿铅锌选矿厂的新工艺和新设备

澳大利亚芒特艾萨矿业有限公司,是世界上铜、银、铅、锌的主要生产基地之一。本文详细介绍了该公司新建的希尔顿选矿厂的生产和所采用的新工艺和新设备。     

THE UNSOLVED MESSAGES OF PEARL HARBOR

In 1941, the United States Navy intercepted enough Japanese naval messages to predict the attack on Pearl Harbor if the code which protected them had been solved. The messages would have disclosed that, while the Japanese government cynically conducted diplomatic negotiations with the United States, the Japanese Combined Fleet under Admiral Isoroku Yamamoto, beginning as early as September 1941, systematically prepared ships, crews, weapons, tactics, and a complicated fuel supply system for the most ambitious operation ever undertaken by the Japanese navy. Details of Japan's intentions were hidden from Navy cryptanalysts because of limited manpower resources and because all Japanese navy codes were assigned a lower priority than Japanese diplomatic codes and German submarine threat.     

Sliding mode control of a shear-mode type ER engine mount

This paper presents feedback control characteristics of a shear-mode type electro-rheological (ER) engine mount. The field-dependent yield stress of an arabic gum-based ER fluid is obtained using a couette type electroviscometer, and it is incorporated into the governing equation of motion of the ER engine mount, which is derived from a bond graph model. A sliding mode controller which directly represents the field-dependent damping force is formulated by taking into account the stiffness and damping properties of the systems as parameter uncertainties. The controller is then experimentally realized by imposing a semi-active actuating condition. The effectiveness of the proposed ER engine mount is demonstrated showing capabilities of isolating the vibrations due to sinusoidal and random excitations.