Design of a wideband conformal array antenna system with beamforming and null steering, for application in a DVB-T based passive radar

The use of radars in detecting low flying, small targets is being explored for several decades now. However radar with counter-stealth abilities namely the passive, multistatic, low frequency radars are in the focus recently. Passive radar that uses Digital Video Broadcast Terrestrial (DVB-T) signals as illuminator of opportunity is a major contender in this area. A DVB-T based passive radar requires the development of an antenna array that performs satisfactorily over the entire DVB-T band. At Fraunhofer FHR, there is currently a need for an array antenna to be designed for operation over the 450-900 MHz range with wideband beamforming and null steering capabilities. This would add to the ability of the passive radar in detecting covert targets and would improve the performance of the system. The array should require no mechanical adjustments to inter-element spacing to correspond to the DVB-T carrier frequency used for any particular measurement. Such an array would have an increased flexibility of operation in different environment or locations.

The design of such an array antenna and the applied techniques for wideband beamforming and null steering are presented in the thesis. The interaction between the inter-element spacing, the grating lobes and the mutual couplings had to be carefully studied and an optimal solution was to be reached at that meets all the specifications of the antenna array for wideband applications. Directional beams, nulls along interference directions, low sidelobe levels, polarization aspects and operation along a wide bandwidth of 450-900 MHz were some of the key considerations.

Expert system aid for design of overload line distribution networks

The use of expert system techniques in power distribution system design is examined. The selection and siting of equipment on overhead line networks is chosen for investigation as the use of equipment such as auto-reclosers, etc., represents a substantial investment and has a significant effect on the reliability of the system. Through past experience with both equipment and network operations, most decisions in selection and siting of this equipment are made intuitively, following certain general guidelines or rules of thumb. This heuristic nature of the problem lends itself to solution using an expert system approach. A prototype has been developed and is currently under evaluation in the industry. Results so far have demonstrated both the feasibility and benefits of the expert system as a design aid.

Crystal design approaches for the synthesis of paracetamol co-crystals

Crystal engineering principles were used to design three new co-crystals of paracetamol. A variety of potential cocrystal formers were initially identified from a search of the Cambridge Structural Database for molecules with complementary hydrogen-bond forming functionalities. Subsequent screening by powder X-ray diffraction of the products of the reaction of this library of molecules with paracetamol led to the discovery of new binary crystalline phases of paracetamol with trans-1,4- diaminocyclohexane (1); trans-1,4-di(4-pyridyl)ethylene (2); and 1,2-bis(4-pyridyl)ethane (3). The co-crystals were characterized by IR spectroscopy, differential scanning calorimetry, and 1H NMR spectroscopy. Single crystal X-ray structure analysis reveals that in all three co-crystals the co-crystal formers (CCF) are hydrogen bonded to the paracetamol molecules through O−H···N interactions. In co-crystals (1) and (2) the CCFs are interleaved between the chains of paracetamol molecules, while in co-crystal (3) there is an additional N−H···N hydrogen bond between the two components. A hierarchy of hydrogen bond formation is observed in which the best donor in the system, the phenolic O−H group of paracetamol, is preferentially hydrogen bonded to the best acceptor, the basic nitrogen atom of the co-crystal former. The geometric aspects of the hydrogen bonds in co-crystals 1−3 are discussed in terms of their electrostatic and charge-transfer components.

Development of a knowledge-based system for cogeneration plant design: Verification, validation and lessons learned

This paper presents the development of a knowledge-based system (KBS) prototype able to design natural gas cogeneration plants, demonstrating new features for this field. The design of such power plants represents a synthesis problem, subject to thermodynamic constraints that include the location and sizing of components. The project was developed in partnership with the major Brazilian gas and oil company, and involved interaction with an external consultant as well as an interdisciplinary team. The paper focuses on validation and lessons learned, concentrating on important aspects such as the generation of alternative configuration schemes, breadth of each scheme description created by the system, and its module to support economic feasibility analysis. (C) 2014 Elsevier B.V. All rights reserved.

Lysine requirements of laying hens

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Design automotivo do pós-guerra ao pós-modernismo : as linhas da Ferrari ao longo do tempo

O presente trabalho foi desenvolvido a partir de um recorte temporal da história do design que compreende o período entre o pós-guerra e o pós-modernismo, com foco no design automotivo promovido pela Scuderia Ferrari, marca italiana de carros esportivos de luxo. Serão abordadas as mudanças sofridas pelo design ao longo do tempo, e de que maneira estas influenciaram em alguns dos projetos mais icônicos da marca na categoria Granturismo – também conhecido pela denominação GT.

BIM for sustainable whole-of-life transport infrastructure asset management

The US National Institute of Standards and Technology (NIST) showed that, in 2004, owners and operations managers bore two thirds of the total industry cost burden from inadequate interoperability in construction projects from inception to operation, amounting to USD10.6 billion. Building Information Modelling (BIM) and similar tools were identified by Engineers Australia in 2005 as potential instruments to significantly reduce this sum, which in Australia could amount to total industry-wide cost burden of AUD12 billion. Public sector road authorities in Australia have a key responsibility in driving initiatives to reduce greenhouse gas emissions from the construction and operations of transport infrastructure. However, as previous research has shown the Environmental Impact Assessment process, typically used for project approvals and permitting based on project designs available at the consent stage, lacks Key Performance Indicators (KPIs) that include long-term impact factors and transfer of information throughout the project life cycle. In the building construction industry, BIM is widely used to model sustainability KPIs such as energy consumption, and integrated with facility management systems. This paper proposes that a similar use of BIM in early design phases of transport infrastructure could provide: (i) productivity gains through improved interoperability and documentation; (ii) the opportunity to carry out detailed cost-benefit analyses leading to significant operational cost savings; (iii) coordinated planning of street and highway lighting with other energy and environmental considerations; iv) measurable KPIs that include long-term impact factors which are transferable throughout the project life cycle; and (v) the opportunity for integrating design documentation with sustainability whole-of-life targets.

Characteristics of high-performance ambipolar organic field-effect transistors based on a diketopyrrolopyrrole-benzothiadiazole copolymer

In this paper, we report the device characteristics of ambipolar thin-film transistors (TFTs) based on a diketopyrrolopyrrole-benzothiadiazole copolymer. This polymer semiconductor exhibits the largest comparable electron and hole mobility values in a single organic semiconductor. The key to realizing such high mobility values, which are $0.5&cm}{2}/\hbox{V}̇\hbox{s, is molecular design, i.e., the use of suitable surface treatments of the source/drain contact electrodes and device architectures, particularly top-gate configurations. The subthreshold characteristics of the TFT devices are greatly improved by the use of dual-gate device geometry. We also report the first measurement of the velocity distribution of electron and hole velocities in an ambipolar organic semiconductor.

A fully integrated 660 MHz low-swing energy-recycling DC-DC converter

A fully integrated 0.18 μm DC-DC buck converter using a low-swing "stacked driver" configuration is reported in this paper. A high switching frequency of 660 MHz reduces filter components to fit on chip, but this suffers from high switching losses. These losses are reduced using: 1) low-swing drivers; 2) supply stacking; and 3) introducing a charge transfer path to deliver excess charge from the positive metal-oxide semiconductor drive chain to the load, thereby recycling the charge. The working prototype circuit converts 2.2 to 0.75-1.0 V at 40-55 mA. Design and simulation of an improved circuit is also included that further improves the efficiency by enhancing the charge recycling path, providing automated zero voltage switching (ZVS) operation, and synchronizing the half-swing gating signals. © 2009 IEEE.

上芒岗金矿床成矿作用过程研究

上芒岗金矿床位于三江褶皱系怒江大断裂西南段，龙陵～瑞丽大断裂(F_1)南东盘，上芒岗次级断裂(F_4)之中。赋矿地层为下二叠统沙子坡组(P_(1s))和中侏罗统勐嘎组(J_(2m))。矿石主要有两种类型，硅质矿石和粘土质矿石；前者主要由石英和少量黄铁矿所组成，金品位平均为2 * 10~(-6)；后者主要由伊利石、高岭石和黄铁矿所组成，金品位一般为2 * 10~(-6) ～ 4 * 10~(-6)。矿石中金星次显微状态，主要元素组合为Au、Ag、As、Sb、Hg、Ba。矿床以强烈的黄铁粘土岩化为特征，热液蚀变作用过程即是金矿化作用过程。根据热液蚀变的矿物共生组合及其生成序次，将金矿化作用过程分为五个阶段：黄铁矿-石英阶段(I)；镁贝得-白云石阶段(II)；辉锑矿-石英阶段(IlI)：黄铁矿-高岭石-伊利石阶段(IV)；网脉状石英阶段(V)。其中黄铁矿-高岭石-伊利石阶段(IV)是金矿化的主成矿阶段。该矿床属于卡林型金矿床。由石英流体包裹体获得不同成矿阶段的温度为，成矿阶段I：210～170 ℃、成矿阶段III：190～160 ℃、成矿阶段V：173～144 ℃。伊利石-水氢同位素温度计测得成矿阶段IV的温度为165 ℃。石英流体包裹体液相成分以K~+、Na~+和Cl~- (F~-)为主，其次为Ca~(2+)、Mg~(2+)和HC0_3~-，由早到晚K~+、Na~+和Cl~-降低，而Ca~(2+)、Mg~(2+)和HC0_3~-升高；气相组分以C0_2为主。石英流体包裹体成分富F，其含量高达8.03 * 10~(-3) mol／kg，正是由于成矿热液富含F，Al才可以与F形成络合物进入热液迁移，即Al成为活动组份，从而形成该矿床所独特的强烈粘土岩化蚀变。稀土元素特征方面，矿石和赋矿地层下二叠统沙子坡以及中侏罗统勐嘎组岩石的稀土配分曲线十分相似，均为右倾型，但是两者的稀土元素总量不同，前者的相对较高。矿石和蚀变岩具有相似的稀土元素配分曲线，但是矿石的稀土元素总量相对较高。与勐嘎组泥岩相比，粘土质蚀变岩和矿石更加富集轻稀土元素，并且更富Eu。这些特征表明，粘土质蚀变岩和矿石是由热液作用形成的，而不是风化作用的产物；矿石与赋矿地层在物质来源上有亲缘关系。不同矿段、不同阶段和不同类型矿石和蚀变岩的Au、Ag、As以及Sb的含量同步变化，这表明在整个成矿作用过程中，成矿流体来源统一，且在成矿体系起主导作用。不同类型的矿石及蚀变岩中Au与Al_20_3，和TFe的含量呈正相关，表明黄铁粘土岩化与成矿关系最为密切。矿石铅同位素~(208)Pb／~(204)Pb、~(207)Pb／~(204)Pb和~(206)Pb/~(204)Pb比值分别为39.12～39.54、15.85～15.95、19.75～20.33；沙子坡组(P_(1s))岩石铅同位素比值分别为:38.407～37.868、15.921～15.589、22.685～22.367;孟嘎组(J_(2m))岩石铅同位素比值分别为：39.499～39.222，15.821～15.772、19.207～18.709。在铅同位素组成相关图中矿石与地层铅的投影点分别集中成群分布。矿石铅与地层铅呈线性分布，而且矿石铅的集中区位于沙子坡组铅集中区和勐嘎组铅集中区之间。这些特征表明矿石铅系由沙子坡组铅和勐嘎组铅混合而成。成矿热液的δ~(18)O由早到晚逐渐升高，I、III、IV、V阶段流体的δ~(18)O值分别为-4.2‰，+0.59‰；+0.76‰，+1.98‰，表现出明显的漂移特征；而δD则表现出高度的一致性，变化范围为-82.5 ～ 79.48‰。由此认为成矿热液系大气降水起源。成矿热液氢、氧同位素组成的这种规律性变化还说明，成矿热液的演化具有继承性和连续性。应用CHILLERR软件包，对上芒岗金矿床的成矿作用过程进行化学反应途径数字模拟。所展示的成矿作用过程为：大气降水沿断裂带下渗，加热循环，获取成矿物质(但不排除有深源成矿物质加入的可能性)；形成起始成矿热液：T = 200℃ P = 228.8bar；pH = 4.4；fs_2 = 10~(-9.89); fo_2 = 10~(-41.28)；aAu(HS)_2~- = 10~(-9.64)，aAuCl_2~- = 10~(-17.86);富含F、Al和Au，贫As、Hg、Zn、Cu和Pb。成矿热液在构造作用的驱动下，上升进入上芒岗断裂上部含水构造破碎带，并与下渗雨水混合而淬冷，形成沿上芒岗断裂呈线状分布的早期硅化石英岩(成矿阶段I)，成矿热液与下渗雨水之比为16:l(成矿阶段I)；继而热液扩散进入下盘破碎带，与白云岩反应，形成矿体下盘的白云石化，水:岩比为193:l(成矿阶段II)。此后成矿热液上升充填裂隙空间，由于热传导而缓慢冷却，成矿体系的温度由189 ℃降为165 ℃，形成含辉锑矿的梳状石英脉(成矿阶段1II)。成矿热液继续上升进入上盘碎屑岩破碎带，停积于构造揉皱的泥质岩，并与之反应，形成上芒岗矿床金矿化的主体—粘占土质矿石，水:岩比为29:1(成矿阶段IV)。最后成矿残液逐渐冷却, 同时伴随C0_2的起泡，形成晚期石英网脉(成矿阶段V)，至此热液金矿化过程结束。由上述可见上芒岗金矿床的成矿作用过程经历了：(初始)成矿热液与下渗大气降水混合(I) → 成矿热液与沙子坡组白云岩反应(II) → 成矿热液缓慢冷却(III) → 成矿热液与勐嘎组泥质岩石反应(IV) → 成矿热液冷却沸腾(V)等5个演化阶段。模拟结果进一步证实了上芒岗金矿床的热液成因。上芒岗金矿床成作用过程化学反应途径数字模拟与地质事实高度吻合，与地球化学研究结果相互印证，再现了上芒岗金矿床的成矿作用过程。由矿床的地质地球化学特征及成矿作用过程化学反应途径模拟结果，归纳出上芒岗金矿床成矿作用过程模型。