长江水质评价和预测的模型研究

本文研究长江水质的评价与预测的模型。对长江近两年水质总体情况和地区分布进行了定性和定量分析。根据近10年(水文年)的主要统计数据进行分析,给出了I—V类、劣V类水无量纲百分比发展趋势和污水排放量发展趋势的超越函数混合模型和趋势图,由此预测未来长江水污染的情势。最后对解决长江水质污染问题提出了几点建议。     

冷链运输装备开门渗风试验及温度场分析

冷藏运输与配送过程中开、关门进行装卸作业易造成货物温度波动,从而影响食品质量,亟待规范.研究对30℃/-18℃条件下冷链配送过程中存在问题进行分析,对装卸时间、是否安装门帘、装卸时是否开启循环风机等状况进行对比试验.在此基础上有针对性地提出完善及规范化的操作方案.认为开门时间长短是影响运输装备内部温度最重要的因素之一,在装卸作业时对大门开启处进行适当的保护则能大大降低冷量的损失,此外,装卸作业时车内循环风机以关闭为宜.     

构建农村经济安全体系的思考

近年来农村经济的发展出现了减缓趋势,农村面临的经济安全问题,必须引起我们高度重视。全面建设小康社会重点在农村,关键是发展农村经济。为了保证农村经济安全、健康、持续的发展,必须构建农村经济安全保障体系。     

论和谐社会构建中体育之促进作用

采用文献资料、逻辑推理、理论等方法,分析了和谐社会的构建拓宽了体育的功能范围,并对体育在和谐社会构建中的作用进行了论述,旨在更新观念,树立“和谐”意识。     

Entanglement in a solid-state spin ensemble

Entanglement is the quintessential quantum phenomenon. It is a necessary ingredient in most emerging quantum technologies, including quantum repeaters, quantum information processing and the strongest forms of quantum cryptography. Spin ensembles, such as those used in liquid-state nuclear magnetic resonance, have been important for the development of quantum control methods. However, these demonstrations contain no entanglement and ultimately constitute classical simulations of quantum algorithms. Here we report the on-demand generation of entanglement between an ensemble of electron and nuclear spins in isotopically engineered, phosphorus-doped silicon. We combined high-field (3.4?T), low-temperature (2.9?K) electron spin resonance with hyperpolarization of the (31)P nuclear spin to obtain an initial state of sufficient purity to create a non-classical, inseparable state. The state was verified using density matrix tomography based on geometric phase gates, and had a fidelity of 98% relative to the ideal state at this field and temperature. The entanglement operation was performed simultaneously, with high fidelity, on 10(10) spin pairs; this fulfils one of the essential requirements for a silicon-based quantum information processor.