Design and validation of a wireless sensor network architecture for precision horticulture applications

This paper proposes a general wireless sensor network architecture for monitoring horticultural crops that are distributed among small plots scattered at distances of up to 10 km from one another. The technology used for the real implementation of the architecture is based on the B-MAC (Berkeley Medium Access Control) medium access protocol to assure a high degree of sensor node power autonomy. To resolve this issue, a series of specialized sensor nodes (Soil-Mote, Environmental-Mote and Water-Mote) have been developed along with a gateway to interconnect them with the farm central offices. Before starting device development, simulations were conducted to ensure that acceptable performance would be achieved with the selected technology in terms of node autonomy, achieved throughput and delays. To that end, it was necessary to implement the selected B-MAC protocol in the ns-2 (Network Simulator-2) simulation framework. The final system was deployed on a real crop to check and validate the simulation results against experimental results.     

Polymers with cavities tuned for fast selective transport of small molecules and ions

Within a polymer film, free-volume elements such as pores and channels typically have a wide range of sizes and topologies. This broad range of free-volume element sizes compromises a polymer's ability to perform molecular separations. We demonstrated free-volume structures in dense vitreous polymers that enable outstanding molecular and ionic transport and separation performance that surpasses the limits of conventional polymers. The unusual microstructure in these materials can be systematically tailored by thermally driven segment rearrangement. Free-volume topologies can be tailored by controlling the degree of rearrangement, flexibility of the original chain, and judicious inclusion of small templating molecules. This rational tailoring of free-volume element architecture provides a route for preparing high-performance polymers for molecular-scale separations.     

Japanese supercomputer technology

Under the auspices of the Ministry for International Trade and Industry the Japanese have launched a National Superspeed Computer Project intended to produce high-performance computers for scientific computation and a Fifth-Generation Computer Project intended to incorporate and exploit concepts of artificial intelligence. If these projects are successful, which appears likely, advanced economic and military research in the United States may become dependent on access to supercomputers of foreign manufacture.     

微机可读写电子磁盘的设计与实现

介绍了一种多功能可读写电子仿真磁盘，它不仅可以替代传统磁盘及驱动器，还可以用来固化用户的应用程序，它仍可利用磁盘操作系统软件，而其读写速度，可靠性，结构安装及性能价格比都是传统的磁盘所不能比拟的，它具有３６０ｋＢＲＯＭ和２５６ｋＢ带拌电保护静态ＲＡＭ，实际所占内存空间仅４ｋＢ它特别适用于环境恶劣并要求高可靠性，高存取速度的工业现场实百自动检测及控制方面存储用户程序和数据。     

电力光载无线通信技术在电力接入网中的应用

分析了电力接入网技术中光纤接入、电力线载波通信、无线公网接入、230电台接入等技术的优缺点,提出了建立高速、双向、实时、集成的电力通信网络是实现智能电网基础的观点,并最大限度地利用电力光载无线通信技术,设计了电力光载无线通信技术模式原理图,构建了输变电在线监测无线通信系统网络架构以及配用电无线通信系统网络架构。     

Forms of memory failure

Memory may fail in a variety of ways. Patients with Korsakoff's syndrome demonstrate global memory deficits similar to those seen in patients with early progressive dementia. Korsakoff's patients, however, may recall rules and principles for organizing information and can gain access to their previously acquired knowledge (semantic memory), whereas recent memory may be grossly impaired. In contrast, dementia patients may have little access to previously acquired knowledge and therefore have great difficulty in organizing and encoding ongoing events. These contrasting forms of memory failure have implications for understanding the structure and mechanisms of memory and learning, particularly the relationship between episodic and semantic memory, as well as the development of therapeutic strategies for cognitive impairments.     

基于Andriod手机客户端访问图书馆的系统设计

随着无线网络通讯技术的发展,利用移动终端设备访问图书馆成为必然模式。文章以Android手机客户端访问图书馆系统为例,主要介绍了系统的架构设计、模块结构设计和数据库设计,以便更深层次地研究无线网络技术和图书馆的有机结合。     

管道智能化管理的发展趋势及展望

国内外长输管道的建设、运行已迈入数字化时代,大量新技术的研发及应用为管道智能化管理提供了技术支撑,同时也提出了挑战。对国内外管道智能化技术的发展现状进行了调研,结合目前管道智能化技术在油气管道行业内的应用情况,建立了“数据层-服务层-应用层”的管道智能化管理核心架构,并提出了“做好顶层设计,将管道数据的管理贯穿管道的全生命周期;坚持以问题为导向,抓住主要矛盾;正确处理好数据、技术、生产与管理的关系”的管理原则。通过对管道智能化管理的典型案例进行分析,总结出了多技术融合的应用趋势,以期为中国管道智能化管理的提升提供参考。     

存储器受限系统的重构技术研究

随着手机、PDA等受实际尺寸和能量(电力)供应限制的这类存储器容量有限的移动设备的广泛应用,如何在有限的存储器内开发更多的功能是所有此类设备开发人员越来越需要考虑的问题.利用重构技术把一些适合于内存容量有限系统的设计模式引入此类系统的开发中是解决这个问题的一个有效的方法,本文探讨了基于此类模式的重构技术并具体的给出了开发示例.     

学习需求下高校图书馆服务模式的探究

分析了互联网背景下高校图书馆工作面临的技术挑战和需求挑战,在该基础上提出新时期高校图书馆服务模式的构建路径,对其系统架构及系统内容进行研究,结合实践经验全面分析高校图书馆服务工作开展中的注意事项并对其进行优化,为高校图书馆建设提供一定的参考。     

软件体系结构

软件体系结构是近来脱颖而出的一个技术领域，面对的是一些新的挑战，正确的体系结构设计是软件系统成功的关键。     

Economic potential of rice precision farming in malaysia: the case study of Felcra Seberang Perak

Many attempts/efforts have been made to cope with the fluctuated production performance in rice production in Malaysia. There is a crucial need in technological advancement to tackle the issue of environmental variability, decreasing productivity and the rising cost in rice cultivation. The use of variable rate technology has increased rice yield through efficient resource allocation. Notwithstanding, an evaluation of the feasibility of this technology is required in terms of economic and intangible benefits. Therefore, this study attempted to determine the potential benefits that could come out of the use of precision agriculture technologies in rice cultivation. A precision farming technology package was developed by the Malaysian Agricultural Research and Development Institute. It consists of two components, namely a variable rate seed application system and a variable rate fertilizer application system. The study estimated the monetary benefits gained from the use of these two technology components at Federal Land Consolidation and Rehabilitation Authority Seberang Perak. The study also compared the performance of the technology package against the conventional practice. The Cost–Benefit Analysis exercise has been implemented to show the benefits and implications comprised in the study. It was found that there is an additional net income per hectare in between Malaysian Ringgit (MYR) 1109 to MYR 1333 due to the reduction in the production cost if the precision farming technology packages were adopted. The advancement in two cultivation stages showed a positive impact monetarily for both small-scale and large-scale farmers in the study. However, many challenges are to be faced for the technologies implementation since the existing rice cultivation recommended practices throughout all stages even yet to be practiced and taken seriously.

     

Computers in science and technology: early indications

Over the past 20 years computer technology has advanced rapidly, especially in the areas of logic and memory. Continued growth at a similar pace can be expected through and probably beyond the 1980's. The technology has already had such major effects on scientific research and engineering that it is of practical importance to try to predict its evolution and uses. It is likely that the trend toward smaller, faster, and cheaper circuits made possible by improved lithographic techniques will continue, resulting in a factor of 10 increase in speed of central processing units and an even greater increase in speed of single-chip microprocessors by the end of the decade. Similar progress is expected in the areas of memory, magnetic storage, printers, and displays. Overall, approximately 20 percent growth annually in the capability of computing systems can be projected. How this continually increasing computing power will affect scientific and engineering activity is more difficult to predict, but some patterns are emerging. Observations of technical personnel at the IBM research laboratory at Yorktown, New York, where the average user has access to a large amount of computing capability and to a worldwide computer network, indicate that workers in different areas have reacted to computer technology in different ways. Whereas engineers have used computing power, displays, and the ability to communicate or share information more or less equally, management has used communication most and scientists have put the greatest value on computing power and displays.     

Three-dimensional optical storage memory

A novel three-dimensional (3-D) optical memory device is presented that allows fast random access of the information and extremely high bit densities. This device is based on two-photon writing, reading, and erasing of the information in a photochromic material embedded in a polymer matrix. Absorption and emission data show that two-photon writing and reading of information is feasible. The advantages and properties of such a 3-D optical memory are discussed.     

Challenges and opportunities of open data in ecology

Ecology is a synthetic discipline benefiting from open access to data from the earth, life, and social sciences. Technological challenges exist, however, due to the dispersed and heterogeneous nature of these data. Standardization of methods and development of robust metadata can increase data access but are not sufficient. Reproducibility of analyses is also important, and executable workflows are addressing this issue by capturing data provenance. Sociological challenges, including inadequate rewards for sharing data, must also be resolved. The establishment of well-curated, federated data repositories will provide a means to preserve data while promoting attribution and acknowledgement of its use.     

VPN技术在农村国土信息网络建设中的应用

介绍了VPN技术的主要类型和实现方式，结合国土部门数字信息管理的需求，研究了VPN技术在建设国土信息网络中的作用，设计了简单易行的VPN接入服务网络结构及其必需的软硬件体系，并针对可能存在的数据安全风险提出了若干对策。     

基于Web的设备管理系统UML建模

 设备是企业组织生产的物质基础,在制造业中起着非常重要的作用。现代设备呈现出结构复杂、功能完善、自动化程度高等特点,只有利用先进的信息技术来对其进行管理,才能有效提高设备管理的工作效率。因此,实现设备管理信息化成为了企业信息化的重要组成部分。然而,随着面向设备管理领域软件体系结构和Web应用复杂性越来越高,原有的CGI、ISAPI等技术,已很难满足对分布式对象访问和操作的需求。所以,本文以实现系统的复用为目标,将组件技术与Web技术相结合,在某烟厂的实际项目 Web-based Equipment Management System（WEMS）开发过程中,采用统一建模语言（UML）对特定领域设备管理软件进行了从需求模型、静态模型、动态模型到物理模型的软件全生命周期可视化建模,提出了分布式系统建模的解决方案。最终,在MicrosoftNET框架下,采用C#语言和SQL2000数据库开发了WEMS系统,同时也验证了该分布式系统建模方案的有效性。     

基于虚拟化环境下的网络安全监控技术应用

在某大型国企的数据中心虚拟化环境背景下，分析虚拟化与云计算安全在网络接入层的“虚拟以太网交换机”（Virtual Ethernet Bridge，VEB）技术在目前的实现方式中的优缺点，研究业界为解决其不足之处所提出的相关方案，阐述采用基于新型网络架构“软件定义网络”（Software Defined Network,SDN）中OpenFlow框架的可行性,提出采用该框架下的Open vSwitch开源技术来实现虚拟网络隔离、QoS配置、流量监控以及数据包分析等虚拟化网络安全监控工作的应用思路。本研究在虚拟网络交换的数据转发与安全控制的解耦、网络安全服务的独立和虚拟网络的安全控制等方面具有创新性，为采用虚拟化和云计算技术的信息系统在接入安全方面提供了参考价值。     

Large-scale molecular dynamics simulations of self-assembling systems

Relentless increases in the size and performance of multiprocessor computers, coupled with new algorithms and methods, have led to novel applications of simulations across chemistry. This Perspective focuses on the use of classical molecular dynamics and so-called coarse-grain models to explore phenomena involving self-assembly in complex fluids and biological systems.     

环境DNA技术在水生生物监测中的挑战、突破和发展前景

近年来,人类活动影响导致水生态系统平衡遭到破坏,水生生物多样性锐减,水生态健康状况堪忧。快速、有效地监测水生生物是评价水生态健康,科学开展水生态环境保护和管理的前提。环境DNA(environmental DNA,eDNA)技术是一种运用分子生物学方法,从环境样品中提取DNA并进行测序和分析来反映物种信息的技术。由于该技术只需采集环境样品(水、土壤、沉积物等)便能获得大量物种信息,具有非入侵性、灵敏性及低成本等特点,近年来备受关注。但是,已有的研究实践表明,目前eDNA技术仍然面临一些挑战,阻碍了其常态化、业务化应用。从生物多样性调查、入侵和濒危物种监测、食性研究等方面列举了eDNA技术在水生生物监测中的应用实例,并总结目前eDNA技术在采样效率、假阳性和假阴性、来源不确定性、数据库缺失和定量结果不准确等5个方面所面临的问题和挑战;进一步探讨研究者针对这些问题所提出的相应解决方案和技术突破。最后,对eDNA技术未来的发展前景进行了展望,以期为研究人员使用eDNA技术提供启发。