Performance Optimization and Parametric Design of a Magnetic Brayton Refrigerator Cycle

基于统计力学和磁工质的热力学性质,建立磁布雷顿制冷机循环新模型,探索热漏、有限速率热传导,绝热过程不可逆性和绝热时间等对循环性能的影响,应用对数平均温差及热力学分析方法,导出制冷率、性能系数的数学表式,并应用数值方法分析、评估磁布雷顿制冷循环的优化性能特性,所得结果为磁制冷机的优化设计和性能改善提供参数设计参考。Based on the statistical mechanics and thermodynamic properties of a magnetic working substance,a new cyclic model of magnetic Brayton refrigerator is established,in which the influence of heat leak,finite-rate heat transfer,adiabatic irreversibilities and adiabatic time are taken into account.By using the Log Mean Temperature Difference(LMTD) and thermodynamic analysis methods,the mathematical expressions of the cooling rate and coefficient of performance(COP)of the magnetic Brayton refrigerator cycle are derived.Furthermore,the optimal performance characteristics of the magnetic Brayton refrigerator cycle are analyzed and evaluated by the numerical calculation technology.The results obtained in the present paper may provide some parametric design message for optimal design and the performance improvement of real magnetic Brayton refrigerators.国家自然科学基金项目(No.50776074

不同形貌普鲁士蓝纳米粒子的合成及光热性能

制备了立方体、直角立方体、球形、棒状、中空状、核壳状、梭形、多面体等8种不同形貌的普鲁士蓝纳米粒子,利用扫描电子显微镜、透射电子显微镜、紫外-可见分光光度计等对纳米粒子进行了表征,考察了普鲁士蓝纳米粒子光热性能的影响因素.结果表明,普鲁士蓝纳米粒子的形貌与光热性能之间联系密切,粒子形貌不同,光热性能不同;当外部实验条件一定时,纳米粒子的形貌、大小、吸收横截面积、尖锐化程度及密实程度等对其光热性能有很大的影响;当纳米粒子形貌一定时,外部因素如激光器的选择、激光功率密度及纳米粒子的浓度等直接影响普鲁士蓝纳米粒子的光热性能;在相同浓度下,激光功率密度越大,纳米粒子的升温效果越明显,光热性能越好;而激光功率密度不变时,纳米粒子浓度越大,其光热转换效率越高.国家自然科学基金(批准号:31271071,31371012,U1505228)资助~

Measurement Method of Logical Gate in Bulk Spin Quantum Computer

提出一种核磁共振量子计算机两量子位逻辑门测量的方案。该方案通过设置适当的标记量子位可显著缩减测量所需输入态数目,给出量子门和具体输入状态集合的实验脉冲序列。包含较少J偶合演化的脉冲序列设计可有效减少操作时间,削弱环境对量子系统的退相干影响。A scheme of measuring two-qubit logical gate is proposed based on nuclear magnetic resonance,which includes the specific input states and complete pulse sequences.In comparison with the approach not using ancillary qubit,this method remarkably reduces the number of the inputs at the cost of flag qubit resource.The pulse sequence with fewer J-coupling evolution can effectively shorten the experiment time and weaken the quantum system decoherence effect by environment.福建省自然科学基金(2008J0219;2009J05152

Performance Optimization and Parametric Analysis of an Irreversible Solar-Driven Stirling Heat Engine

建立不可逆太阳能STIrlIng热机循环系统,研究太阳能集热器辐射对流热损、有限速率热传导、回热器的回热损失及其它不可逆因素对系统性能的影响。基于热力学分析方法和最优控制理论,导出系统总效率和集热器工作温度所满足的优化方程,确定和评估相关性能界限和优化设计参数值,并详细讨论包括与传热系数有关的综合因子、回热损失因子以及辐射和对流热损因子比等重要参量对太阳能STIrlIng热机系统性能的定量影响。所得结果为太阳能STIrlIng热机参数优化设计提供理论参考。An irreversible solar-driven Stirling heat engine system is established,in which not only radiation-convection heat losses from the solar collector to the ambient but also the regeneration loss and other irreversibilities of the heat engine are taken into account.Based on thermodynamic analysis method and the optimal control theory,the optimum relationship between the overall efficiency of the system and the operating temperature of the collector are derived and the related performance bounds and optimal value of the design parameters are determined and evaluated.Moreover,the effects of several important parameters including the compositive factor related to the heat transfer coefficient,the regenerative factor and the radiation and convection heat loss coefficient ratio on the performance of the heat engine system are discussed in detail.The results obtained may provide some theoretical references for the optimal parameter design of solar-driven Stirling heat engines.国家自然科学基金资助项目(No.50776074

PERFORMANCE OPTIMIZATION AND PARAMETER DESIGN of AN IRREVERSIBLE SOLAR-DRIVEN HEAT PUMP SYSTEM

考虑集热器辐射对流热损等多种不可逆因素,建立不可逆三热源太阳能热泵系统新模型,基于热力学分析方法,导出系统总性能系数与集热器工作温度关系的解析表达式,揭示了集热器的辐射对流热损、有限速率热传导和工质内部不可逆性等对系统性能特性的影响,分析和讨论了在最大总性能系数下太阳能热泵系统的优化设计参量。A new irreversible solar-driven three-heat-source pump system was presented,in which multi-irreversibilities including the radiation and convection heat losses of the collector were taken into account.Based on thermodynamic analysis method,the analytical expression between the overall coefficient of performance of the system and the operating temperature of the solar collector was derived.The effects of radiation and convection heat losses of the collector,finite-rate heat transfer and internal irreversibility inside the working fluid on the performance characteristics of the system were revealed.Furthermore,the optimal design parameters of the system at the maximum overall coefficient of performance were analyzed and discussed.国家自然科学基金(51176160);教育部高校博士点基金(20090121110026);中央高校基本科研业务费专项基金(201112G006

Subspace quantum process tomography via nuclear magnetic resonance

基于三核自旋量子系统实现了内嵌两量子位子空间量子过程重构.通过输入完备态集合对执行的量子过程进行了表征.由于量子过程内嵌于子空间,使得重构实验所需输入次数及时间显著减少,同时实验尽量避免使用时间较长的J偶合演化,有效控制了系统的退相干。Experimental investigation of subspace quantum process tomography in three-spin system was implemented via nuclear magnetic resonance.A quantum process was characterized by measuring a complete set of input states and corresponding outputs.The method using ancillary qubit remarkably reduces the number of the initial input states.And the pulse sequences used in this paper have fewer J-coupling evolutions.The experiment time was shortened and quantum decoherence of the system was weakened efficiently.福建省自然科学基金(批准号:2008J0219)资助的课题---

Asymmetric Transfer Hydrogenation of Aromatic Ketones Catalyzed by New Chiral Diaminodiphosphine-Iridium(I) Systems

合成了含-CH3取代基的PnnP型手性双胺双膦配体,并采用核磁共振、质谱、红外光谱及圆二色光谱等方法对其进行了表征.在异丙醇溶液中,考察了该配体与[IrHC l2(COd)]2组成的手性胺膦-铱体系对多种芳香酮的不对称转移氢化性能.结果表明,该手性胺膦-铱体系是催化多种芳香酮不对称氢转移氢化的优秀催化剂.在室温下,用该体系催化1,1-二苯基丙酮时,可得到99%的转化率和99%EE的对映选择性.The chiral PNNP ligands containing-CH3 substituents have been synthesized and characterized by NMR,MS,IR and CD spectra.The chiral diaminodiphosphine-iridium(I) systems,prepared in situ from [IrHCl2(COD)]2 and the ligands 1 and 2,have been explored.The catalytic performance was investigaed in the asymmetric transfer hydrogenation of various aromatic ketones in iPrOH.The results indicated that the catalytic system acted as an excellent catalyst precursor in asymmetric transfer hydrogenation of various aromatic ketone.When the(R,R)-2/[IrHCl2(COD)]2 as catalyst was employed for the reduction of the 1,1-diphenylacetone at room tempreture,high activity(99% conversion) and excellent enantioselectivity(99% ee) were obtained.国家自然科学基金(No.2042300220703034);福建省自然科学基金(No.2008J0235);广西自然科学基金资助(No.0832192

Chinese Revolution in the Socio-economic Perspective

自2004年起,本刊设立开放时代论坛,每年11月第一个周末定期举办,至今已逾十二届。开放时代论坛旨在邀集多领域学者,推进对前沿公共议题的跨学科讨论。自2015年起,本刊再设不定期的开放时代工作坊,旨在邀集某学科或某些相近学科的学者,对学科内与时势相接的重要学术问题作专门探讨。第一次开放时代工作坊于2015年1月13日至14日在中山大学举办,主题为“社会经济史视野下的中国革命“,我们希望从长时段、日常生活、地方社会的角度展现中国革命的复杂性、丰富性和延续性,以区别于惯行的党史研究。以下内容根据第一次开放时代工作坊录音整理而成,并经所有发言人审订。评论及讨论部分的小标题为编者所加。因篇幅所限,部分内容未能一并刊出