基于缓存机制的作物模型Web服务并发处理

为了改善作物模型Web服务的响应时间,该文提出了基于缓存机制的作物模型Web服务并发处理方案。通过综合分析作物模型Web服务的组合结构、数据Web服务的通信特性以及作物模型Web服务的响应时间特征,以多线程处理和数据缓存技术为基础,设计了基于缓存机制的作物模型Web服务并发处理方案;并以作物栽培管理知识模型Web服务为测试对象,在真实网络环境下,验证了该方案的有效性。结果表明,在单用户多地点请求和多用户多地点请求情况下,采用并发处理方案分别可以缩短32%和35%的模型服务响应时间,极大地提高了模型的多用户并发处理能力。该研究为作物模型的区域应用提供了技术支撑。     

基于Java的Tank游戏单机版的设计分析——Tank的显示以及键盘事件的处理

介绍了Java语言的主要特征,对设计坦克游戏的双缓存机制做了详细研究,并且给出了具体的实现代码。游戏主要是由玩家通过键盘来控制的,所以文中对于键盘事件的处理做了原理性的论述,并且编写了键盘事件处理的关键代码。     

.NET CF中SQL CE数据库开发核心技术

文章阐述了嵌入式数据库的定义和特点,嵌入式数据库SQL CE的简单介绍,并重点介绍了.NET精简框架中SQLCE数据库开发的核心技术。在核心技术介绍中,以C#语言为例讲解了SqlCeConnection类、SqlCeCommand类、SqlCeDataReader类、SqlCeDataAdapter类的使用,为实际应用开发做好理论铺垫。     

基于Android平台的农业新品种推广信息采集系统

介绍了Android平台的系统架构、特点及配套使用的SQLite嵌入式数据库,总结了基于Android平台的农业新品种推广信息采集系统开发环境的搭建和系统的特点,指出了该系统的不足之处及需要改进的方向。     

基于嵌入式组件技术的精准农业农田信息采集系统的设计与实现

基于精确地理位置的农田信息采集是实施精准农业的基础工作。介绍了一种基于掌上电脑和DGPS/背夹式GPS设备的农田信息采集系统的开发过程。该系统在Microsoft eMbedded Visual C++ 3.0集成开发环境下,采用嵌入式GIS开发组件,实现了掌上电脑环境下GPS、GIS功能的集成。系统由GPS实时通讯和数据处理模块、基于WinCE的基本GIS功能模块和农田信息采集功能模块等组成模块,能够实现与DGPS设备或背夹式GPS设备的实时通讯和定位数据的解析,实现了矢量农田地理信息的显示、操作、查询等基本GIS功能,同时,系统能够采集农田地物分布和多种影响作物生长的环境差异性信息。该文还介绍了使用Microsoft数据库访问组件对象ADOCE对Pocket Access数据库的操作方法,实现了对嵌入式农田信息采集系统中农田信息的有效管理。     

轮胎嵌入式超高频无源RFID系统的功率传递特性

轮胎嵌入式超高频无源 RFID 系统在轮胎生命周期管理和安全监控中将发挥十分重要的作用。为此,该文研究了轮胎嵌入式超高频无源RFID系统功率传递特性。轮胎嵌入式超高频无源RFID系统中,读写器和电子标签间的无线链路需要穿过空气和轮胎,路径损耗主要包括空气-轮胎界面间的反射损耗和轮胎中的衰减。基于轮胎介电常数和空气-轮胎界面的边界条件,研究轮胎嵌入式超高频无源RFID系统功率传递特性,提出了一种基于终端开路同轴探针的轮胎介电常数的比对测量方法,建立了轮胎嵌入式超高频无源 RFID 系统功率传递模型。数值分析表明,提出的基于端开路同轴探针的轮胎介电常数的比对测量方法误差小,测量、仿真的反射系数差的绝对值小于0.04,而为了提高轮胎嵌入式超高频无源RFID系统读取距离和可靠性,读写器天线应采用水平极化方式,并且尽可能直视电子标签;应合理设计电子标签嵌入轮胎的深度,避免功率传递函数处于波谷位置。该研究可为轮胎嵌入式超高频无源RFID电子标签与胎压监测系统的设计提供参考。     

基于ZigBee和嵌入式技术的无线安防监控系统研究与设计

针对传统有线安防系统的局限性,通过对zigbee技术和嵌入式技术的研究,提出了一种基于zigbee组网技术和嵌入式控制技术的住宅小区无线安防监控系统,实现了布防后能够对住宅小区生活中存在的火灾、盗窃、煤气泄漏等安全隐患进行监测及报警。采用基于ZigBee标准的射频芯片CC2430,实现节点间数据的无线传输,并给出了系统的硬件原理框图和软件设计思路。     

嵌入式农产品追溯码加密算法设计与实现

利用便携式终端设备快速高效生成农产品追溯码是保障追溯码可信度、增强信息完备度和提高企业效率的有利手段。该文以基于地理坐标的农产品追溯码为编码方式,改进高级加密标准(advanced encryption standard,AES)算法,设计并实现了一种基于嵌入式平台的农产品追溯码加密算法;利用LPC1766处理器硬件平台和Keilu Vision3软件平台测试了算法的存储空间和运算速度,为将算法移植到其他嵌入式平台提供了参考。嵌入式平台上实现密钥的动态变化和追溯码的唯一性,为利用终端进行农产品可靠安全追溯提供了保障,最后给出了算法在农产品质量追溯标识打印终端中的应用方案。     

异构数据库系统数据共享及实现

本文系统地介绍了异构数据库的特点,详细分析了实现异构数据库共享的三种方法（数据库转换、基于中间件和数据库网关）的优缺点,并通过两个例子阐述了在PowerBuilder环境下基于数据管道技术和ODBC中间件技术来实现数据共享的方法。     

苹果－瓦楞纸板缓冲跌落动力学模型

基于瓦楞纸板受冲击压缩变形的特征,提出-表征其非线性冲击力-变形模型,结合其跌落冲击试验结果表征模型参数.在此基础上,建立"富士"苹果-瓦楞纸板缓冲跌落动力学模型方程,进行不同高度下的苹果缓冲跌落冲击响应的理论分析,并与试验结果进行比较.结果表明,试验结果与理论模型结果吻合性好,所提出苹果-瓦楞纸板缓冲跌落冲击模型能合理地表征苹果缓冲跌落冲击动力学特征,瓦楞纸板能显著降低苹果跌落的冲击加速度.研究结果为果品缓冲包装设计提供了理论基础.     

缓冲液种类对土壤酸性磷酸酶活性的影响

土壤酸性磷酸酶影响土壤有机磷矿化。选择不同的缓冲液种类和不同p H值测定土壤酸性磷酸酶活性,可影响数据的可比性。为明确缓冲液及p H值对不同土壤磷酸酶活性的影响程度,选取p H值4～8的土壤样本,测定了在醋酸盐缓冲液、柠檬酸盐缓冲液和MUB缓冲液3种不同培养条件下酸性磷酸酶活性变化。结果表明,采用MUB缓冲液条件可获得较稳定的土样区分序列,且与缓冲液的p H值的变化无关。在醋酸盐缓冲液和柠檬酸盐缓冲液条件下,不同p H值范围的不同土样之间土壤酸性磷酸酶活性变异系数变化剧烈,而采用MUB缓冲液获得的变异系数较其他缓冲液大,且趋势平稳。综合考虑,进行土壤酸性磷酸酶活性测定,可优先选用MUB缓冲溶液。     

基于农机空间轨迹的作业面积的缓冲区算法

农机规模化管理与市场化作业服务需要准确、实时、便捷的农机作业面积测量方法。该研究基于农机空间运行轨迹,设计了作业面积测量的矢量缓冲区算法和栅格缓冲区算法,并通过农机满幅作业和重叠作业对比试验,检验了上述2种缓冲区算法与距离测量算法分别在R1K(real time kinematic,实时动态差分)、亚米级和单点定位3种不同GNSS(global navigation satellite system,全球导航卫星系统)定位精度条件下的测量相对误差。试验结果表明:当农机具备自动导航满幅作业条件时,距离测量算法在任何定位精度下均能获得较高精度测量结果;缓冲区算法仅在差分定位时测量精度较高。当农机无导航重叠作业时,距离测量算法的误差会随着作业重叠率的增加而显著增大,而缓冲区算法不受作业重叠的影响,测量精度稳定。目前国内仍普遍采用人工操控的农机作业方式,重叠作业不可避免,缓冲区测量算法能够提供更加准确的作业面积测量结果。     

Modification of the Mehlich Lime Buffer Test

Routine use of the Shoemaker, McLean, and Pratt (SMP) lime buffer method resulted in chronic problems with electrode reference junction degradation, stability of readings relative to contact time, and generation of hazardous waste. During method recalibration, the Mehlich buffer was chosen for parallel evaluation with SMP, with the goal of improving method performance and eliminating of hazardous waste. The Mehlich buffer was modified by substituting calcium (Ca) for barium (Ba). The modified Mehlich (MM) buffer was found to be identical to the original with respect to buffering power and linearity over an extended pH range of 3.0–6.6. Seven agronomic soils were incubated with eight rates of calcium carbonate for 90 days. Regression analysis was performed to predict lime requirement (LR) to several target pH levels, based on pH measured in each buffer alone or in both water and buffer. Slightly better predictability was obtained using multiple regressions, with R²>0.95 in all cases. Significant but minor differences occurred between the newly calibrated buffers in extended comparisons. The MM buffer was superior to the SMP during routine usage, with fewer adverse effects on electrodes and the elimination of hazardous waste.     

Comparison of Shoemaker–McLean–Pratt and Modified Mehlich Buffer Tests for Lime Requirement on Pennsylvania Soils

Abstract

The Shoemaker–McLean–Pratt (SMP) buffer test is commonly used in Pennsylvania and throughout the United States to determine the lime requirement (LR) of acid soils. The buffer contains potassium chromate, a carcinogen, and all waste must be collected for disposal in a hazardous waste facility. An alternative to the SMP buffer is the Mehlich buffer. Although the Mehlich buffer contains barium chloride (BaCl₂), also a hazardous and regulated compound, calcium chloride (CaCl₂) has been shown to be an effective substitute. The goal of this study was to compare the SMP buffer and the modified Mehlich buffer (CaCl₂ substituted for BaCl₂) for estimating LR on PA soils and to determine if the modified Mehlich buffer could provide an effective alternative to the SMP test. Twenty‐two agriculturally important Pennsylvania soils with pH values ranging from 4.5 to 6.4 were collected, and the actual LR of each soil was determined by incubating soils for 3 months with calcium carbonate. The modified Mehlich buffer was a more accurate predictor of the lime required to raise soils to either pH 6.5 (r²=0.92) or 7.0 (r²=0.87) in comparison to the SMP buffer (r²=0.87 and 0.82, respectively). Comparison of calibration equations for Mehlich buffer versus lime requirement derived in this study were similar to those developed on soils from other states and geographic regions.     

Development of buffer methods and evaluation of pedotransfer functions to estimate pH buffer capacity of highly weathered soils

The pH buffer capacity of a soil (pHBC) determines the amount of lime required to raise the pH of the soil layer from its initial acid condition to an optimal pH for plant growth and the time available under current net acid addition rate (NAAR) until the soil layer acidifies to a critical pH leading to likely production losses. Accurate values of pHBC can also be used to calculate NAAR from observed changes in soil pH. In spite of its importance, there is a critical shortage of pHBC data, likely due to the long period of time needed for its direct measurement. This work aimed to develop quick, simple and reliable methods of pHBC measurement and to test these methods against a slow (7‐day) titration used as benchmark. The method developed here calculates pHBC directly from the pH buffer capacity of the buffer solution and the increase in soil pH and corresponding decrease in pH of the buffer solution following mixing and equilibration. The pHBC values calculated using Adams and Evans or modified Woodruff buffers were in accord with those measured by slow titration. Buffer methods are easily deployed in commercial and research laboratories as well as in the field. The advantage of using buffer solutions to calculate pHBC instead of lime requirement is the broad application of this soil property. The pHBC of a soil is an intrinsic property that would not be expected to need remeasurement over periods of less than decades. Recurring lime requirement can be calculated from the soil's pHBC, initial and target pH values. A large proportion of the variability in pHBC was explained by the soil organic carbon content. This relationship between pHBC and soil organic carbon content allowed us to develop local pedotransfer functions to estimate pHBC for different regions of Australia.     

土壤对污染物的缓冲性研究

阐述了土壤缓冲性概念的演变,提出从缓冲性角度研究土壤污染的思路及体系。通过几种土壤对Cu、Pb、Cd、F缓冲性测定,分析了影响因素;由土壤pH值、粘粒、碳酸钙、有机质、腐殖酸、外源镉等一系列单因素试验,研究了各因素与缓冲性量变规律;通过等温吸附、络合特性、溶解性、形态分布,吸附动力学试验,研究了缓冲机制;还进行了各因素综合影响试验及通径分析。在试验研究基础上,为土壤污染的防治、调控、预测预报提出了科学依据。     

The effect of the function type for describing the soil buffer power on calculated ion transport to roots and nutrient uptake from the soil

The relationship between amount of a nutrient in soil and its concentration in solution, the buffer curve, is usually non‐linear. However, most models that calculate nutrient transport in the soil and nutrient uptake by the plant often assume a linear buffer curve because of simpler programming. In this paper a model is presented that uses the Freundlich function to describe the non‐linear buffer curve in the soil. It has been shown that calculated uptake and depletion curves were not influenced by the shape of the buffer curve. In a sensitivity analysis the buffer capacity, soil solution concentration, soil water content, soil impedance factor, maximum influx and the curvature of the Freundlich function were varied and the influence on calculated uptake was studied. The buffer capacity in general had a minor influence and the linearity or non‐linearity of the buffer capacity had under no circumstances an influence on calculated uptake. Thus, the use of a linear buffer curve in transport models does not lead to a significant error in the results.     

用于防控菜地排水中氮磷污染的缓冲带技术初探

太湖地区菜地复种指数高、施肥量大,其排水中N、P浓度较高,容易造成受纳水体的富营养化,针对这一问题,在野外构建了不同宽度的缓冲带,分别研究了缓冲带适宜种植的植物以及缓冲带不同宽度条件下对菜地排水中各形态N、P的拦截效果。结果表明,与水稻、空心菜相比,狗牙根更适合作为缓冲带植物;随着缓冲带宽度的增加,缓冲带对菜地排水中各形态N、P的拦截效率在逐渐增加,但其拦截效率的增幅却在逐渐降低,综合考虑N、P拦截所应达到的效果指标和节约用地的原则,缓冲带的最佳宽度应设置为1.5 m,此时缓冲带对溶解态N、P的处理效率分别为30.3%和54.9%,对颗粒态N和P的去除效果分别达到91.2%和94.4%,对总N(颗粒态+溶解态)和总P(颗粒态+溶解态)的去除效果分别达到56.1%和85.9%,缓冲带宽度为1.5 m时菜地和缓冲带面积之比为100:11。     

Evaluation of Modified Mehlich and Sikora Buffer Methods as an Alternative to Modified Woodruff Buffer in Determining Lime Requirement for Missouri Soils

The modified Woodruff buffer (MWB) test is used to determine lime requirement (LR) for Missouri soils. Though this method is proven to work for Missouri soils, it uses p-nitrophenol, which is a hazardous substance. Soil-testing laboratories are under increasing pressure to reduce hazardous wastes, which must be collected and disposed of following U.S. Environmental Protection Agency protocols. The goal of this study was to evaluate the modified Mehlich buffer (MMB) and the Sikora buffer (SB) as alternatives to the MWB in determining the LR for Missouri soils. Thirty soils were collected from major agricultural areas in Missouri, treated with calcium carbonate (CaCO₃), and incubated for 90 days. Soil pH_s [0.01 M calcium chloride (CaCl₂) 1:1] was regressed against CaCO₃ rate, and the actual LR was estimated for each soil to raise the soil pH_s to target levels of 5.8, 6.3, and 6.8. The MWB, MMB, and SB pHs were regressed against the actual LR for all 30 soils to evaluate the effectiveness of each test for estimating the LR. The MMB and SBs were found to be as good as or better than MWB in predicting LR in Missouri soils. Both buffers (MMB and SB) were found to be equally effective in generating accurate estimates of the LR to raise soils to pH_S 5.8, 6.3, and 6.8 (for pH values 5.8: R² = 0.76, 0.82, 0.81; for pH values 6.3: R² = 0.80, 0.88, 0.86; and pH values 6.8: R² = 0.77, 0.89, 0.87 for MWB, MMB, and SB, respectively). A test to evaluate the stability of the buffers over time indicated that MMB had the shortest bench life (about 21 days) when compared to the MWB and SB, thus making it less feasible for use by soil test laboratories. Based on performance and stability, SB is a better alternative than MWB for Missouri soils.     

湘西典型植烟土壤酸碱缓冲特性及影响因素

为探明山地植烟土壤酸碱缓冲特性,采集了湘西山区烤烟典型生产区的28个土壤样本,采用酸碱滴定法和灰色关联法分析了湘西山地植烟土壤酸碱缓冲特性以及土壤缓冲容量与各影响因素之间的量化关系。结果表明：湘西山地植烟土壤酸碱缓冲量为11.35~43.29 mmol·kg^-1,平均为17.26 mmol·kg^-1,黄棕壤的酸碱缓冲量（11.35~43.29 mmol·kg^-1）显著高于黄壤（11.79~20.70 mmol·kg^-1）。有78.57%的样本对酸碱敏感,黄壤土是否对酸敏感由有机质含量决定,黄棕壤土是否对酸敏感与pH和有机质含量密切相关。对于同一土壤类型,有机质和黏粒含量与酸碱缓冲容量显著正相关;对于黄棕壤,酸碱缓冲容量还与pH和阳离子交换量呈显著正相关,与交换性酸和交换性铝呈显著负相关。主要土壤类型之间缓冲性能存在较大差异,黄壤土酸碱缓冲性能主要受土壤有机质、阳离子交换量和黏粒含量的影响;黄棕壤土酸碱缓冲性能主要受pH、阳离子交换量和有机质的影响。在生产中应采用合理施用化肥、增施有机肥、调节土壤酸性等措施提高植烟土壤酸碱缓冲性能,为优质烟叶生产创造良好的生态环境。