陕北黄土区陡坡地人工植被的土壤水分生态环境

通过定点土壤水分测定与对比分析,研究了陕北黄土区35~45°陡坡地人工植被的土壤水分亏缺状况、年际、年内动态变化规律、干燥化特征及其补偿恢复特征。结果表明:陡坡地多年生人工植被的土壤水分亏缺极为严重,贫水年0~10m土层贮水量仅相当于田间持水量的26.2%~42.0%,丰水年贮水量也仅占田间持水量的27.0%~43.3%;亏缺次序为:柠条>刺槐>苜蓿>侧柏>杨树>油松>荒坡>杏>枣>农地。年际间同一植被土壤水分含量的变化主要发生在200 cm以上土层内,变异程度随土壤深度的增加而减弱。同一生长季,各种植被0~120 cm土层含水量的变异系数都较大,但植被间差异较小;120 cm以下土层,变异系数较小,但植被间差异较大。陡坡地多年生植被均有永久干层存在,但深层土壤干燥化强度因植物种类和生长年限而存在明显的差异。雨季土壤水分的补偿和恢复深度为1.0~1.4m,但不同植被的土壤贮水增量和补偿度有较大差异。同一植被丰水年的雨水补偿深度比干旱年可增加60 cm以上,5m土层贮水增量增加3倍以上。在自然降雨条件下,陡坡地多年生人工植被的土壤贮水亏缺状况不能得到改善,土壤干化现象也不可能有所缓解。

沙地樟子松人工林稳定性研究

本文分析了生态系统稳定性的含义、影响稳定性的时间空间尺度和干扰因子；对人工林稳定性的内涵作了解释，提出了人工林稳定性的评价标准；以此作为稳定性研究的理论依据。首先分析了影响沙地樟子松人工林稳定性的各种干扰因子，通过对沙地樟子松人工林造林成活、生长情况、对不良外界环境的抗御能力、对环境影响作用的大小、林分生产力和林分结构的评价分析。最后提出维持沙地人工林稳定的对策。

农牧交错带不同人工植被下荒漠化土壤肥力的变化

研究了陕北农牧交错带荒漠化土地上种植人工植被后,在不同的植被恢复类型和生长状态下土壤物理、化学和生物学性状的特征。结果表明,随着人工植被的建立与生长,土壤肥力总体趋于好转,土壤理化性质得到显著改善,土壤质地变细,微生物数量增加,土壤酶活性增强;同时,使流动沙地向半固定、固定沙丘方向转化。但随着植被盖度和植被种类的不同,不同样地土壤肥力差异很大;多年生乔木林改良土壤肥力的潜力最高,耕作粗放的农地土壤肥力有所下降。

智能人工腿步速测量数字电路的设计与分析

智能人工腿是一个精密的机电一体化装置，其关键部件之一是步速测量电路。作者提出一种新的步速测量方法，即测量人工腿在摆动相的持续时间，用该时间的长短来间接反映步速的快慢，设计电路时，采用自顶向下（Top-Down）的设计方法，其核心内容是将测量系统按不同功能分割成几个模块，然后分别设计每一个模块电路，最后，用1片ispLSI1016高密度可编程芯片并采用ISP（In System Program）编程方法调离同步速测量电路。ISP编程方法的优点是可以现场修改，调速测量系统电路，并且不需要仿真器装置，实验结果表明：设计的这种步速测量电路结构合理，可有效地实现对智能人工腿步速的测量。

Intelligence Without Reason

Computers and Thought are the two categories that together define Artificial Intelligence as a discipline. It is generally accepted that work in Artificial Intelligence over the last thirty years has had a strong influence on aspects of computer architectures. In this paper we also make the converse claim; that the state of computer architecture has been a strong influence on our models of thought. The Von Neumann model of computation has lead Artificial Intelligence in particular directions. Intelligence in biological systems is completely different. Recent work in behavior-based Artificial Intelligenge has produced new models of intelligence that are much closer in spirit to biological systems. The non-Von Neumann computational models they use share many characteristics with biological computation.

Resonant and Secular Orbital Interations

In stable solar systems, planets remain in nearly elliptical orbits around their stars. Over longer timescales, however, their orbital shapes and sizes change due to mutual gravitational perturbations. Orbits of satellites around a planet vary for the same reason. Because of their interactions, the orbits of planets and satellites today are different from what they were earlier. In order to determine their original orbits, which are critical constraints on formation theories, it is crucial to understand how orbits evolve over the age of the Solar System. Depending on their timescale, we classify orbital interactions as either short-term (orbital resonances) or long-term (secular evolution). My work involves examples of both interaction types. Resonant history of the small Neptunian satellites In satellite systems, tidal migration brings satellite orbits in and out of resonances. During a resonance passage, satellite orbits change dramatically in a very short period of time. We investigate the resonant history of the six small Neptunian moons. In this unique system, the exotic orbit of the large captured Triton (with a circular, retrograde, and highly tilted orbit) influences the resonances among the small satellites very strongly. We derive an analytical framework which can be applied to Neptune's satellites and to similar systems. Our numerical simulations explain the current orbital tilts of the small satellites as well as constrain key physical parameters of both Neptune and its moons. Secular orbital interactions during eccentricity damping Long-term periodic changes of orbital shape and orientation occur when two or more planets orbit the same star. The variations of orbital elements are superpositions of the same number of fundamental modes as the number of planets in the system. We investigate how this effect interacts with other perturbations imposed by external disturbances, such as the tides and relativistic effects. Through analytical studies of a system consisting of two planets, we find that an external perturbation exerted on one planet affects the other indirectly. We formulate a general theory for how both orbits evolve in response to an arbitrary externally-imposed slow change in eccentricity.

Exploiting virtual prototyping for reliability assessment

Products manufactured by the electronics sector are having a major impact in telecommunications, transportation space applications, biomedical applications, consumer products, intelligent hand held devices, and of course,the computer. Demands from end-users in terms of greater product functionality, adoption of environmentally friendly materials, and further miniaturization continually pose several challenges to electronics companies. In the context of electronic product design and manufacture, virtual prototying software tools are allowing companies to dramatically reduce the number of phsysical prototypes and design iterations required in product development and hence reduce costs and time to market. This paper details of the trends in these technolgies and provides an example of their use for flip-chip assembly technology.

Review of the technology and reliability issues arising as optical interconnects migrate onto the circuit board

Light has the greatest information carrying potential of all the perceivable interconnect mediums; consequently, optical fiber interconnects rapidly replaced copper in telecommunications networks, providing bandwidth capacity far in excess of its predecessors. As a result the modern telecommunications infrastructure has evolved into a global mesh of optical networks with VCSEL’s (Vertical Cavity Surface Emitting Lasers) dominating the short-link markets, predominately due to their low-cost. This cost benefit of VCSELs has allowed optical interconnects to again replace bandwidth limited copper as bottlenecks appear on VSR (Very Short Reach) interconnects between co-located equipment inside the CO (Central-Office). Spurred by the successful deployment in the VSR domain and in response to both intra-board backplane applications and inter-board requirements to extend the bandwidth between IC’s (Integrated Circuits), current research is migrating optical links toward board level USR (Ultra Short Reach) interconnects. Whilst reconfigurable Free Space Optical Interconnect (FSOI) are an option, they are complicated by precise line-of-sight alignment conditions hence benefits exist in developing guided wave technologies, which have been classified into three generations. First and second generation technologies are based upon optical fibers and are both capable of providing a suitable platform for intra-board applications. However, to allow component assembly, an integral requirement for inter-board applications, 3rd generation Opto-Electrical Circuit Boards (OECB’s) containing embedded waveguides are desirable. Currently, the greatest challenge preventing the deployment of OECB’s is achieving the out-of-plane coupling to SMT devices. With the most suitable low-cost platform being to integrate the optics into the OECB manufacturing process, several research avenues are being explored although none to date have demonstrated sufficient coupling performance. Once in place, the OECB assemblies will generate new reliability issues such as assembly configurations, manufacturing tolerances, and hermetic requirements that will also require development before total off-chip photonic interconnection can truly be achieved

The potential of offshore windfarms to act as marine protected areas – A systematic review of current evidence

As offshore windfarm (OWF) construction in the UK is progressing rapidly, monitoring of the economic and ecological effects of these developments is urgently needed. This is to enable both spatial planning and where necessary mitigation in an increasingly crowded marine environment. One approach to mitigation is co-location of OWFs and marine protected areas (MPAs). This systematic review has the objective to inform this co-location proposal and identify areas requiring further research. A limited number of studies addressing marine renewable energy structures and related artificial structures in coastal waters were found. The results of these studies display a change in species assemblages at artificial structures in comparison to naturally occurring habitats. An increase in hard substrata associated species, especially benthic bivalves, crustaceans and reef associated fish and a decrease in algae abundance were the dominant trends. Assemblages associated with complex concrete structures revealed greater similarity to natural hard substrata compared to those around steel structures. To consider marine renewable energy sites, especially large scale OWFs as MPAs, the dissimilar nature of assemblages on the structures themselves to natural communities should be considered. However positive effects were recorded on the abundance of commercially important crustacean species. This suggests potential for incorporation of OWFs as no fishing, or restricted activity zones within a wider MPA to aid fisheries augmentation. The limited available evidence highlights a requirement for significant further research involving long term monitoring at a variety of sites to better inform management options.

Responding to crisis: When the telephone fails

The world is changing. Advances in telecommunications have meant that the world is shrinking – data can be moved across continents in the time it takes to send an email or access the cloud. Although developments such as these highlight the extent of scientific and technological evolution, in terms of legal liability, questions must be asked as to the capacity of our legal structures to evolve accordingly.

This article looks at how emergency telephone provision and any shift to VoIP systems might fit with existing tort liability and associated duty implications. It does so by analysing the technology through the principles that signpost UK tort law. This article recognises that as an emerging area, the legal liability implications have not yet been discussed in any great detail. The aim of this article therefore is to introduce the area, encourage debate and consider the issues that may become increasingly relevant as these types of technologies become industrial standards.

Interaction of pollen-specific actin-depolymerizing factor with actin

We have examined the interaction of recombinant lily pollen ADF, LIADF1, with actin and found that whilst it bound both G- and F-actin, it had a much smaller effect on the polymerization and depolymerization rate constants than the maize vegetative ADF, ZmADF3. An antiserum specific to pollen ADF, antipADF, was raised and used to localize pollen ADF in daffodil - a plant in which massive reorganizations of the actin cytoskeleton have been seen to occur as pollen enters and exits dormancy. We show, for the first time, an ADF decorating F-actin in cells that did not result from artificial increase in ADF concentration. In dehydrated pollen this ADF:actin array is replaced by actin:ADF rodlets and aggregates of actin, which presumably act as a storage form of actin during dormancy. In germinated pollen ADF has no specific localization, except when an adhesion is made at the tip where actin and ADF now co-localize. These activities of pollen ADF are discussed with reference to the activities of ZmADF3 and other members of the ADF/cofilin group of proteins.