MEMS Electronically Steerable Antennas for Fire Control Radars

Large apertures are of great benefit to applications that are prime powered limited as is found on aerostat and other airborne platforms. Electronically scanned array antennas are often proposed for these applications. However, increasing the aperture area with conventional array technology is met with prohibitive cost, weight, and prime power increases because of the dense spacing of phase shifters and/or active T/R modules. This discusses the recent development of RF MEMS (Microelectromechanical System) switch technology and the use of these switches in a Radanttrade lens configuration for arrays of approximately 10 m² at X-band. A proof-of-concept 0.4 m² MEMS Electronically Steerable Antenna (ESA) containing 25,000 MEMS switches has been successfully designed, fabricated, and tested. The 0.4 m² MEMS ESA was then integrated with an AN/APG-67 radar system to form the MEMS Demonstration Radar System. The MEMS Demonstration Radar System successfully detected both airborne and ground moving targets during a series of extensive radar demonstrations. This is believed to be the first large scale employment of MEMS switches in a scanning antenna and radar system. The low-cost, lightweight, and low power technology demonstrated can enable weight and power constrained platforms with electronic steering.     

Characteristics of Icy Surfaces

The surfaces of the Solar System’s icy satellites show an extraordinary variety of morphological features, which bear witness to exchange processes between the surface and subsurface. In this paper we review the characteristics of surface features on the moons of Jupiter, Saturn, Uranus and Neptune. Using data from spacecraft missions, we discuss the detailed morphology, size, and topography of cryovolcanic, tectonic, aeolian, fluvial, and impact features of both large moons and smaller satellites.     

无飞机 无增值

"No Plane,No Gain"无飞机,无增值这是美国公务航空协会提出的一个观点,意思是不使用公务航空,企业难以实现持续增值,使用公务飞机并非纯粹是"炫富"和"烧钱"。     

寻夏之旅

每年的6月21日或22日,为夏至日,此时太阳直射北回归线。这一天,在中国最北的漠河北极村,一天24小时几乎都是白昼。这一天,在中国南边的云南墨江、广东从化、广西桂平,正午时分"立竿无影"。这一天,山东的人在吃面,而广西的人在吃狗肉……从北至南,在夏至这一天,你会看到最不同的风俗,也会看到最特别的景致,所以,让我们马上开始一次寻夏之旅。     

Surface, Subsurface and Atmosphere Exchanges on the Satellites of the Outer Solar System

The surface morphology of icy moons is affected by several processes implicating exchanges between their subsurfaces and atmospheres (if any). The possible exchange of material between the subsurface and the surface is mainly determined by the mechanical properties of the lithosphere, which isolates the deep, warm and ductile ice material from the cold surface conditions. Exchanges through this layer occur only if it is sufficiently thin and/or if it is fractured owing to tectonic stresses, melt intrusion or impact cratering. If such conditions are met, cryomagma can be released, erupting fresh volatile-rich materials onto the surface. For a very few icy moons (Titan, Triton, Enceladus), the emission of gas associated with cryovolcanic activity is sufficiently large to generate an atmosphere, either long-lived or transient. For those moons, atmosphere-driven processes such as cryovolcanic plume deposition, phase transitions of condensable materials and wind interactions continuously re-shape their surfaces, and are able to transport cryovolcanically generated materials on a global scale. In this chapter, we discuss the physics of these different exchange processes and how they affect the evolution of the satellites’ surfaces.     

Lunar Reconnaissance Orbiter Camera (LROC) Instrument Overview

The Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) and Narrow Angle Cameras (NACs) are on the NASA Lunar Reconnaissance Orbiter (LRO). The WAC is a 7-color push-frame camera (100 and 400 m/pixel visible and UV, respectively), while the two NACs are monochrome narrow-angle linescan imagers (0.5 m/pixel). The primary mission of LRO is to obtain measurements of the Moon that will enable future lunar human exploration. The overarching goals of the LROC investigation include landing site identification and certification, mapping of permanently polar shadowed and sunlit regions, meter-scale mapping of polar regions, global multispectral imaging, a global morphology base map, characterization of regolith properties, and determination of current impact hazards.     

酷路泽的时尚精神

丰田FJ酷路泽正式上市已经5个多月的时间了,其时尚前卫的个性、超凡的越野性能,为国内SUV市场增添了些许别样的风景。疯狂的越野迷们也与FJ酷路泽一同,挑战了种种险路阻途。FJ迷们表示,无论是在高温炙烤的沙漠中跋涉沙海,还是在风雪中破冰击雪,FJ酷路泽都能,以金刚般的意念勇往直前。     

第十四届北京国际航空展·汽车 汽车品牌的航空DNA

航空背景所带来的技术优势对汽车的品牌定位可能并无多大帮助,但在理念的层面上,却出现惊人的一致,那就是对"高端"的追求。航空发动机需要的是万无一失的细腻,豪华车主需要的是唯我独尊的精致,而两者,都需要最佳的服务精神。"北京国际航空展"是国内历史最久最专业的航空展。它汇聚中国航空业全部权威机构,得到航空领域相关机构的鼎力支持。历届北京航展吸引了世界14个国家及地区超过129个展商,17000名专业观众参与,北京国际航空展已经成为国内外航空产业同仁高度关注的交流和合作专业展会。第十四届北京国际航空展主题为:环保、科技、安全、商业,2011年9月21日至24日在北京举行。     

2011上海车展环保看点 绿色的未来

4月,两年一度的上海车展靓丽登场。本届上海车展总规模将超过20万平方米,创下国内之最。在本届上海车展的主题"创新未来"推动下,各大车企再次在新能源汽车的研发和推广上下足工夫,纷纷在环保、绿色等字眼上大做文章。特别是在日本地震之后,日本品牌更在意"地球很危险",积极准备在车展上推出自己的绿色产品。     

夏至养生

四时养生法就是按照一年四季的变化规律和特点,调节人体各部分的机能,从而达到健康长寿的目的。自然界的阴阳变化、四季更替、日夜轮回必然会影响到人体生理和病理,因此养生必须采取相应的措施。即所谓春退、夏平、秋进、冬补。