咸阳地压地热流体补给的环境同位素证据

通过对咸阳地压地热流体的环境同位素研究,系统论证了咸阳地压地热流体的补给来源、补给方向及补给年代。研究表明:咸阳地压地热流体的补给来源主要为全新世前古大气降水,其补给方向主要来自研究区西部及西北部,除局部深大断裂附近有少量现代降水补给外,其可更新能力较差。     

校园卡网银充值功能的实现

校园卡人工现金充值人力成本高,易失误,且存在安全隐患。某大学开发实现了使用中行网银向校园卡充值转账的功能,使学生足不出户,通过互联网就可以自助完成校园卡的充值业务。校园卡网银充值丰富了校园卡充值渠道,适应了当代青年学生的行为喜好,体现了校园卡的个性化服务。     

一种UUV锂电池系统实时监测及控制方法

聚合物锂离子电池因其能量密度高、使用寿命长、无记忆失效等特点正逐渐成为UUV (unmaned underwater vehicles)能源的主体,而准确地检测锂电池的充放电和使用状态对锂电池的寿命和水下作业的正常进行有着至关重要的作用.通过对锂电池技术和UUV技术的研究,设计出了一种新型的可监控多节(40节以上)锂电池串联的监测管理系统,数据通过CAN总线输出,且该系统能够实现对各节电池的均衡充电.海试应用证明了该系统准确性好、实时性强和稳定性高.     

Impacts of Climate Change on Water Resources Availability and Agricultural Water Demand in the West Bank

Global climate change is predicted as a result of increased concentrations of greenhouse gasses in the atmosphere. It is predicted that climate change will result in increasing temperature by 2 to 6°C and a possible reduction of precipitation of up to 16% in the Mediterranean basin. In this study, the West Bank is taken as a case study from the Mediterranean basin to evaluate the effects of such climate change on water resources availability and agricultural water demands. Due to the uncertainty in climate change impacts on temperature and precipitation, a number of scenarios for these impacts were assumed within the range of predicted changes. For temperature, three scenarios of 2, 4 and 6°C increase were assumed. For precipitation, two scenarios of no change and 16% precipitation reduction were assumed. Based on these scenarios, monthly evapotranspiration and monthly precipitation excess depths were estimated at seven weather stations distributed over the different climatic and geographical areas of the West Bank. GIS spatial analyses showed that the increase in temperature predicted by climate change could potentially increase agricultural water demands by up to 17% and could also result in reducing annual groundwater recharge by up to 21% of existing values. However, the effects of reduced precipitation resulting from climate change are more enormous as a 16% reduction in precipitation could result in reducing annual groundwater recharge in the West Bank by about 30% of existing value. When this effect is combined with a 6°C increase in temperature, the reduction in groundwater recharge could reach 50%.     

On the predictability of the water-table variation in a ditch-drainage system

The irrigation in regions of brackish groundwater in many parts of the world results in the rise of the water-table very close to the groundsurface. The salinity of the productive soils is therefore increased. A proper layout of the ditch-drainage system and the prediction of the spatio-temporal variation of the water table under such conditions are of crucial importance in order to control the undesirable growth of the water-table. In this paper, an approximate solution of the nonlinear Boussinesq equation has been derived to describe the water-table variations in a ditch-drainage system with a random initial condition and transient recharge. The applications of the solution is discussed with the help of a synthetic example.Notations a lower value of the random variable representing the initial water-table height at the groundwater divide - a+b upper value of the random variable representing the initial water-table height at the groundwater divide - h variable water-table height measured from the base of the aquifer - K hydraulic conductivity - L half width between ditches - m ₀ initial water-table height at the groundwater divide - N(t) rate of transient recharge at time t - N ₀ initial rate of transient recharge - P N ₀/K - S Specific yield - t time of observation - t ₀ logarithmic decrement of the recharge function - T Kt/SL - x distance measured from the ditch boundary - X x/L - Y h/L - Y mean of Y - Y Variance of Y     

On the prediction of groundwater mound formation due to transient recharge from a rectangular area

Recharge to the aquifer leads to the growth of a groundwater mound. Therefore, for the proper management of an aquifer system, an accurate prediction of the spatio-temporal variation of the water table is very essential. In this paper, a problem of groundwater mound formation in response to a transient recharge from a rectangular area is investigated. An approximate analytical solution has been developed to predict the transient evolution of the water table. Application of the solution and its sensitivity to the variation of the recharge rate have been illustrated with the help of a numerical example.Notations a = Kh/e [L²/T] - A = aquifer's extent in the x-direction [L] - B = aquifer's extent in the y-direction [L] - e = effective porosity - h = variable water table height [L] - h ₀= initial water table height [L] - h = weighted mean of the depth of saturation [L] - K = hydraulic conductivity [L] - m, n = integers - P = constant rate of recharge [L/T] - P ₁+P₀= initial rate of transient recharge [L/T] - P ₁= final rate of transient recharge [L/T] - s = h ²–h ₀ ² [L²] - t = time of observation [T] - x,y = space coordinates - x ₂–x₁= length of recharge area in x-direction [L] - y ₂–y₁= width of recharge area in y-direction [L] - z = decay constant [T^-1]     

一种小型智能割草机器人的设计与实现

针对传统割草机污染高、噪音大和需要人工长时间操作等弊端,结合市场需求,研制了一款小型的可预约工作、自主回充的智能割草机器人。硬件上,系统以STM32为核心,由控制系统、动力系统、传感系统、通信系统和人机交互系统5部分组成;算法和软件上,采用自主回充方案,实现预约模式下机器人多次工作,减少人工操作;为解决机器人在斜坡上无法直线行进问题,设计了一种坡度补偿算法;同时为提高机器人的割草效率,提出了一种自主寻草算法。系统符合国际安全设计指标,经过长时间测试,机器在预约模式、自主回充模式均能稳定可靠的工作。     

铝电解电容器测试分选机的设计方案

JHT-LD-380型高精度电容器全自动测试分选机是铝电解电容器生产专用设备。该机选用了ST-280型电解电容器测试电桥,该电桥集极性、漏电流、电容量、损耗各参数的测试及通过I/O接口对外部电路进行控制于一体,性能优异。电桥与外围电路配合良好。在测试电桥、充电片、测试头等关键点的设计上独具匠心。该机具有自动分选、操作简便、测试准确、速度快等优点,在测试精度、速度、分选准确度等方面均达到国外同类机的水平。1998年评为国家级新产品。     

智能电网建设助推电动汽车业快速发展

电动汽车业的发展,是改变交通模式及能源消费结构,加速我国实现低碳经济目标的有效途径。分析了电动汽车业的发展对电网规划、建设、运行、服务方面带来的挑战,说明了智能电网是电动汽车规模化应用的基础,介绍了智能电网中柔性充放电、双向互动、集中监控、商业运营技术的电动汽车能源供给技术研究及实践情况,对电动汽车业发展的创新商业运营模式进行了展望。     

三江平原浅层地下水超采问题探讨(一)

三江平原地下水是否超采,争议已久.笔者经过"九五"期间国家三江攻关和垦区科技攻关研究(主要为1997～1998年),又经过近10 a的追踪反馈研究分析,尤其地下水动态分析,认定三江平原地下水从宏观而论,没有超采,仍有很大开发潜力,尤其如友谊、萝北各农场及沿江潜水地区(包括引提自流灌区).其中建三江弱承压水地区,至今虽尚未超采,但今后还要大面积发展水田的情况下,应在调蓄利用当地丰富降水资源(提高利用率和增加对地下水补给率)和在地下水开采后周边大江大河可能增加激发补给量的分析研究计算上下功夫,从而判断或避免是否可能超采.至今三江平原地下水没有超采,就是生产实践对"九五"期间国家与垦区攻关科技成果的最好肯定.