Using irrigation intervals to optimize water-use efficiency and maize yield in Xinjiang,northwest China

Worldwide, scarce water resources and substantial food demands require efficient water use and high yield.This study investigated whether irrigation frequency can be used to adjust soil moisture to increase grain yield and water use efficiency(WUE) of high-yield maize under conditions of mulching and drip irrigation.A field experiment was conducted using three irrigation intervals in 2016: 6, 9, and 12 days(labeled D6, D9, and D12) and five irrigation intervals in 2017: 3, 6, 9, 12, and 15 days(D3, D6, D9, D12, and D15).In Xinjiang, an optimal irrigation quota is 540 mm for high-yield maize.The D3, D6, D9, D12, and D15 irrigation intervals gave grain yields of 19.7, 19.1–21.0, 18.8–20.0, 18.2–19.2, and 17.2 Mg ha^-1 and a WUE of 2.48, 2.53–2.80, 2.47–2.63, 2.34–2.45, and 2.08 kg m-3, respectively.Treatment D6 led to the highest soil water storage, but evapotranspiration and soil-water evaporation were lower than other treatments.These results show that irrigation interval D6 can help maintain a favorable soil-moisture environment in the upper-60-cm soil layer, reduce soilwater evaporation and evapotranspiration, and produce the highest yield and WUE.In this arid region and in other regions with similar soil and climate conditions, a similar irrigation interval would thus be beneficial for adjusting soil moisture to increase maize yield and WUE under conditions of mulching and drip irrigation.

A Simple and Highly Efficient Enantioselective Synthesis of (<i>S</i>)-Rivastigmine

A highly efficient and convenient procedure for the enantioselective synthesis of (S)-Rivastigmine, a cholinergic agent for the treatment of mild to moderate dementia of the Alzheimer’s type and dementia due to Parkinson’s disease, is accomplished by the treatment of versatile, readily accessible (S)-(-)-2-methyl-2-propanesulfinamide with 3-hydroxyacetophenone. This protocol provides high yield and excellent enantiomeric excess in short step synthesis.

HF-RFID与UHF-RFID在图书管理应用中的对比分析

RFID技术在图书馆中应用越来越广泛,但是在产品的选择上有高频和超高频两种产品,本文对这两种产品进行了对比分析,同时探讨图书馆应用RFID技术标准以及引发的对读者隐私权保护方面的一些情况,希望能够对图书馆在RFID产品的选择上提供帮助。

基于AC-Link技术串联谐振高压充电电源串并联特性研究

对基于AC-Link技术串联谐振高压充电电源的串并联特性进行了研究,对电源模块参数差异和模块间同步对多个模块串并联特性进行了分析,研究结果表明:电源模块参数差异和模块间同步对电源并联特性没有影响,电源模块参数差异,导致输出平均电流大小不一致,随着充电时间的延长,串联模块间输出电压差异越大,模块间不同步时间决定串联模块间输出电压的差异,不随充电时间变化。研制了两台充电速率30k J/s,输出电压30k V的高压充电电源进行实验验证,实验结果表明:充电充电源可工作于串并联两种工作模式,串联工作时输出电压为60k V,电源模块输出电压差异小于负载电压的2.5%。

>35%5-junction space solar cells based on the direct bonding technique

Multijunction solar cells are the highest efficiency photovoltaic devices yet demonstrated for both space and terrestrial applications.In recent years five-junction cells based on the direct semiconductor bonding technique(SBT),demonstrates space efficiencies>35%and presents application potentials.In this paper,the major challenges for fabricating SBT 5J cells and their appropriate strategies involving structure tunning,band engineering and material tailoring are stated,and 4-cm235.4%(AM0,one sun)5J SBT cells are presented.Further efforts on detailed optical managements are required to improve the current generating and matching in subcells,to achieve efficiencies 36%-37%,or above.

Petrogenesis and tectonic implications of Late-Triassic high εNd(t)-εHf(t) granites in the Ailaoshan tectonic zone(SW China)

High εNd（t）-εHf（t） granites are robust evidence for crustal growth. In this paper we report results of petrologic, geochronological and geochemical investigations on the Huashiban granites from the Ailaoshan tectonic zone in western Yunnan （SW China）. Zircon grains separated from the two samples （10HH-119A and 10HH-120A） yield the weighted mean 206pb/238u ages of 229.9 ± 2.0 Ma and 229.3 ± 2.3 Ma, respectively, interpreted as the crystallization ages of the granites. Based on our results, in combination with the existing U-Pb geochronological data for the Ailaoshan metamorphic rocks, we propose that the Ai- laoshan Group might be a rock complex composed of the Mesoproterozoic, Neoproterozoic, Hercynian, Indosinian and Hima- layan components, rather than a part of the crystalline basement of the Yangtze block. The zircon grains show highly depleted Lu-Hf isotope compositions, with positive eHf（t） values ranging from 8.4 to 13.1. The Huashiban granites have high SiO2 （72.66 wt%-73.70 wt%）, low Mg# （0.28-0.34） with A/CNK=1.01-1.05, and can be classified as peralumious high-K calc-alkaline I-type granites. A synthesis of these data indicates that the Ailaoshan tectonic zone had evolved into a post-collisional setting by the Late-Triassic （229 Ma）. Genesis of the Huashiban high εNd（t）-εHf（t） granites involved into two processes： （1） underplating of the sub-arc mantle into the lower crust, and （2） remelting of the juvenile crustal materials in re- sponse to the upwelling of the asthenospheric mantle in the post-collisional setting.

高频交流链接技术充电电源

在高频交流链接技术(HF AC-link)充电电源理论、数值仿真和实验研究的基础上,研制了一台充电速率为60kJ/s、输出电压为50kV的样机。电源主要由LC三相滤波器、矩阵开关、串联谐振单元和高频变压器4部分组成,分别给出了这几个部分的详细设计。利用高频交流链接技术的优势和合理的结构设计,使得该充电电源的功率密度大于0.6 W/cm3,同时实验结果表明,该充电电源的功率因数大于0.95,效率大于90%。因此,该充电电源具有高功率密度、高功率因数和高效率的优点。

基于高频交流链接技术的串联谐振变换器

提出了一种基于高频交流链接技术的串联谐振变换器,简要分析了该变换器的工作原理及一个周期内的工作过程,给出了变换器的控制方式和控制系统的框图,并进行了仿真和实验验证。实验结果表明,该变换器能够实现网侧电压和电流同相位,且网侧电流谐波含量低,同时串联谐振又具有高效率和恒流特性。因而,变换器具有高功率因数、高效率和低谐波的优点。

基于模糊综合层次法的短波通信系统效能评估

短波通信是重要的远程军事通信手段之一,其效能高低直接决定了完成通信保障任务能力的强弱。论文提出了一种层次分析法和模糊综合法结合而成的模糊综合层次法对短波通信系统进行了效能评估,并通过模糊综合指数法对评估结果向量进行了单值化处理,所得到的最终评估结果客观可信,贴近实际,有助于掌握其执行远程通信保障的能力状况。

高效电源在电除尘器提效改造中的组合应用

高压电源作为电除尘器的重要组成部分,直接关系到电除尘器的收尘效率,如何选择高压电源设备对电除尘器的提效改造意义重大。文章结合工程实例,介绍了高效电源组合在燃煤锅炉配套电除尘器提效改造项目中的应用情况。