检索结果-南通市图书馆

FloodNet： Coupling Adaptive Sampling with Energy Aware Routing in a Flood Warning System

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2007年第1期22卷 121-130页

作者：周菁 David De Roure School of Computer and Software Communication University of China Beijing 100024 China School of Electronics and Computer Science University of Southampton U.K.

We describe the design of FloodNet, a flood warning system, which uses a grid-based flood predictor model developed by environmental experts to make flood predictions based on readings of water level collected by a set of sensor nodes. To optimize battery consumption, the reporting frequency of sensor nodes is required to be adaptive to local conditions as well as the flood predictor model. We therefore propose an energy aware routing protocol which allows sensor nodes to consume energy according to this need. This system is notable both for the adaptive sampling regime and the methodology adopted in the design of the adaptive behavior, which involved development of simulation tools and very close collaboration with environmental experts.

关键词： adaptive sampling communication system routing energy awareness environmental sensor networks

GIS approach for assessment of land suitability for different land use alternatives in semi arid environment in Jordan:Case study(Al Gadeer Alabyad-Mafraq)

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Information Processing in Agriculture 2019年第1期6卷 91-108页

作者： Safa Mazahreh Majed Bsoul Doaa Abu Hamoor GIS unit National Centre for Agricultural Research and Extension(NCARE)Baqa’Jordan

The semi arid lands of Jordan are fragile and severely degraded due to low rainfall and mismanagement of natural *** human demands increase,sustaining the productivity of land becomes more and more *** suitability evaluation can contribute towards better land management;mitigation of land degradation;and designing land use pattern that prevents environmental problems through segregation of competing land *** analysis allows identifying the main limiting factors for the agricultural production and enables decision makers to develop crop managements able to increase the land *** purpose of this study was to develop a Geographic Information System(GIS)based approach for land use suitability assessment in order to assist land managers to identify areas with physical limitations for different land use alternatives based on research criteria developed by FAO and modified by *** study was conducted using various data and maps incorporated within(GIS)in order to derive potential suitability for different Land utilization Types(LuTs).Land suitability mapping was developed using an innovative approach that integrates soil and climatic data for land suitability *** maps for each land use were developed to show the suitability classes and display the spatial representation of soils suitable for *** output of suitability analyses provided not only the type of land use for which the land was suitable,but also information about the type of limitation(s)facing the utilization of the *** land use alternatives(scenarios)were formulated to improve and optimize the agricultural production in the study area.

关键词： Land utilization types Soil survey Land suitability criteria Suitability mapping GIS Scenarios

Estimate of the lower-limb-specific muscle parameters during bipedal walking for humans,apes and early hominids with the implications for the evolution of body proportion

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

仪器仪表学报 2007年第8期28卷 1358-1366页

作者： WangWeijie Institute of Motion Analysis and Research Department of Orthopedic and Trauma Surgery Dundee University Dundee DD1 9SY UK Supported in part by the grants from the Biotechnology and Biological Sciences Research Council the Leverhulme Trust and the Natural Environment Research Council U.K.

Modern human has different body proportion from early hominids and great *** with others,in general,modern human adults have relatively long lower limb and heavier body *** the lower limbs provide support to the whole body and play an important role in walking,it is proposed that the ratio of the lower limb to the whole body for modern human could be beneficial to bipedal *** study tried to estimate the muscle parameters of the lower limb in walking for the subjects with various body *** a simplified musculoskeletal model,some muscle parameters of the lower limb,*** force,stress,work and power,were estimated for modern human adult,child,AL 288-1(the fossil specimens of Australopithecus afarensis,3.18 million years old)and *** results show that with the body proportion modern human adult spends less muscle work and power in walking than other *** results imply that using the cost of transport(*** muscle work of the lower limb per unit of displacement)as the criteria,the early hominids,if their body proportions were structurally similar to AL 288-1,could evolve towards what modern human adult looks like,in order to save energy during bipedal walking.

关键词：人类进化原始人类猿直立行走下肢肌肉工作参数压力

Design of atmospheric composition monitor based on ultraviolet optical absorption technology

在线全文

学校读者我要写书评

暂无评论

Optoelectronics Letters 2011年第5期7卷 384-388页

作者：李文军 Bio-Incubator Imperial College London

An open path atmospheric composition monitor is designed based on ultraviolet differential absorption *** current correction and diode response correction are used to improve the detection limit and Savitzky-Golay filter is used to improve the measurement *** experimental results show that the designed system has the ability to measure NO and NO 2 in real time with reasonable *** detection limit of the system is about 0.25 ppm for NO and 0.28 ppm for NO 2 .When the concentration level of the target gases is below 100 ppm,the system has good linearity and high measurement accuracy,i.e.,the measurement accuracy is about 2%for NO and about 4%for NO 2 .The detection limit of dark current can be improved by about 5 to 10 ppb,and the correction of diode response can improve the detection limit by around 30 *** window average can improve the detection limit at low concentration levels but will generate more errors at higher concentration ***,the designed system meets the requirement of measuring multi-species air pollutants in real time and accurately.

关键词：吸收技术大气成分监测器设计紫外基础测量精度线光

Total Fragmentation Cross Section of 158A GeV Lead Projectiles in Cu Target

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2008年第9期25卷 3208-3211页

作者： Mukhtar Ahmed Rana Shahid Manzoor Physics Division Directorate of Science PINSTECH PO Nilore Islamabad Pakistan

Total fragmentation cross section for the reaction 158A Pb ions ＋ Cu target is measured using the most sensitive track detector CR-39. Measured values are compared with calculations. Exposures of target-detector stack with 158A P5 projectiles are made at CERN-SPS beam facility. Results of calibration of CR-39 detector in a charge region （63 ≤ Z ≤ 83） are also reported, which can be used for high energy particle identification using CR-39 and in determination of partial charge changing cross sections. The charge resolution δz achieved by this technique is about 0.2e. A systematic dependence of total fragmentation cross section on target properties is revealed and the corresponding results are presented.

关键词： the power-law exponents precipitation durative abrupt precipitation change

LAGRANGIAN METHOD uSED IN THE RESEARCH OF ATMOSPHERIC CIRCuLATION

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta meteorologica Sinica 1991年第2期5卷 129-140页

作者：陆汉城雷兆崇 Nanjing Institute of Meteorology Nanjing and C.N.Duncan University of EdingburghU.K.

Based on the conservation of entropy and potential vorticity in adiabatic atmospheric motion without the consideration of friction,calculation is made of the trajectory of a particle on an isentropic surface by use of the data of FGGE *** of several calculation schemes of the trajectory discussed show that the local data interpolation and Runge-kutta time-integral scheme is the *** calculated trajectory reflects the large-scale atmospheric motion only and the small-scale motion emerges as a deviation term of the calculated *** then the outbreak and propagation of planetary wave are studied by means of the deformation of a material line,with the result showing that the material line can be tracked in the trop- osphere only in a few days,beyond which the interaction between the small-scale waves and large-scale motion leads to its dramatical twisting and ***,the Lagrangian method is assumed to be an effective means of diagnostic research in the nonlinear intcraction in atmospheric circulation,in addition to the general study of the atmospheric circulation.

关键词： lagrangian method trajectory material line surf zone outbreak

Position tracking and attitude control for quadrotors via active disturbance rejection control method

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2019年第1期62卷 5-14页

作者： Yuan YuAN Lei CHENG Zidong WANG Chong SuN Department of Computer Science Brunel University London School of Astronautics Northwestern Polytechnical University

In this paper, a trigonometric-saturation-function-based position controller is designed for the quadrotor system with internal and external disturbances. Furthermore, in the attitude control problem, a dual closed-loop structure is put forward. Specifically, a nonlinear extended-state-observer(ESO) is employed to provide an estimate for the so-called total disturbance. Then, based on the estimate provided by the ESO,a nonlinear composite control strategy is designed for the purpose of angular tracking. Some sufficient conditions are established to guarantee that the position and attitude subsystems are stable. The contributions are mainly as follows.(1) A trigonometric-saturation-function is used in the position control which could guarantee that the studied system is fully-actuated.(2) The nonlinear ESO is implemented in the attitude control-loop which could enhance the anti-disturbance property. Finally, some numerical simulations and practical experiments are provided to verify the applicability of the proposed methodology.

关键词： position control quadrotor system extended-state-observer attitude control

Building a Distributed Infrastructure for Scalable Triple Stores

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2009年第3期24卷 447-462页

作者：周菁 Wendy Hall David De Roure School of Computer Science Communication University of China School of Electronics and Computer Science University of SouthamptonSouthamptonU.K.

Built specifically for the Semantic Web, triple stores are required to accommodate a large number of RDF triples and remain primarily centralized. As triple stores grow and evolve with time, there is a demanding need for scalable techniques to remove resource and performance bottlenecks in such systems. To this end, we propose a fully decentralized peer-to-peer architecture for large scale triple stores in which triples are maintained by individual stakeholders, and a semantics-directed search protocol, mediated by topology reorganization, for locating triples of interest. We test our design through simulations and the results show anticipated improvements over existing techniques for distributed triple stores. In addition to engineering future large scale triple stores, our work will in particular benefit the federation of stand-alone triple stores of today to achieve desired scalability.

关键词： peer-to-peer RDF data management semantics awareness scalability topology reorganization

Approximation-free Control for Hydraulic Servo Systems without using Backstepping

在线全文

学校读者我要写书评

暂无评论

Approximation-free Control for Hydraulic Servo Systems witho...