长江经济带农业水资源利用效率时空差异分析

长江经济带水资源总量充沛,但人均水资源量以及单位面积耕地占有量处于较低水平;农业用水量超过供水总量的50%,而农业水资源利用效率低。研究长江经济带农业水资源利用效率对保护长江具有重要的现实意义。基于Malmquist-Panel Data两阶段模型,对长江经济带农业水资源利用效率的时空差异特征及其影响因素进行了分析研究。分析结果表明:经济发展水平、第一产业固定资产投资额、水资源禀赋、节水农业发展水平、"长江经济带"国家战略的实施、区域变量以及部分时间变量等对农业水资源利用效率具有显著的正向影响,而种植结构即粮食播种面积占比则有着显著的负向影响;长江经济带农业水资源利用效率时空差异特征明显。因此,对于长江经济带,应因地制宜、合理规划农作物种植结构;同时,加强地区间的技术交流与合作,实现长江经济带整体发展与各区域特色发展协同共进。     

基于SOC的串联锂离子电池组均衡策略研究

由于一致性问题的存在,成组电池在可用容量、使用寿命等方面远不及单体电池,电池组的均衡管理对电池的成组使用者有着重要的实际意义.论文就针对锂离子串联电池组的均衡技术进行了研究,首先介绍了电池组一致性问题产生的原因,指出均衡管理的重要意义,分析了锂离子电池组SOC的一致性和基于SOC的均衡策略,详细阐述了基于SOC的均衡技术实现,最终搭建实验平台进行测试,验证了所使用的均衡策略和硬件电路的有效性.     

Experimental dynamic characterizations and modelling of disk vibrations for HDDs

Currently, the rotational speed of spindle motors in HDDs (Hard-Disk Drives) are increasing to improve high data throughput and decrease rotational latency for ultra-high data transfer rates. However, the disk platters are excited to vibrate at their natural frequencies due to higher air-flow excitation as well as eccentricities and imbalances in the disk-spindle assembly. These factors contribute directly to TMR (Track Mis-Registration) which limits achievable high recording density essential for future mobile HDDs. In this paper, the natural mode shapes of an annular disk mounted on a spindle motor used in current HDDs are characterized using FEM (Finite Element Methods) analysis and verified with SLDV (Scanning Laser Doppler Vibrometer) measurements. The identified vibration frequencies and amplitudes of the disk ODS (Operating Deflection Shapes) at corresponding disk mode shapes are modelled as repeatable disturbance components for servo compensation in HDDs. Our experimental results show that the SLDV measurements are accurate in capturing static disk mode shapes without the need for intricate air-flow aero-elastic models, and the proposed disk ODS vibration model correlates well with experimental measurements from a LDV.     

悬空石墨烯/六方氮化硼异质结焦耳热红外辐射器件的可控制备与光电性能研究(特邀)EI北大核心CSCD

石墨烯具有优异的光、电、热以及力学性质,而悬空石墨烯避免了衬底带来的褶皱、载流子散射和掺杂等影响因素,可以充分展现石墨烯的本征物理特性,因此在高性能石墨烯微电子和光电子器件研究中具有重要意义。然而,目前悬空石墨烯器件还存在着制备方法复杂、成品率低、性能不稳定等挑战。文中提出了一种利用六方氮化硼吸附石墨烯,将其定点转移到金属电极,制备悬空石墨烯焦耳热红外辐射器件的新方法。六方氮化硼对悬空石墨烯具有良好的支撑悬挂作用,有效提高了悬空石墨烯的力学稳定性,避免了坍塌、断裂等失效情况。真空热退火处理后悬空石墨烯的电阻降低到退火处理前的约六分之一,载流子迁移率比退火前提高了约18倍。当偏置电压为8 V时,拉曼光谱测试发现石墨烯温度为836 K,器件在955 nm波长处表现出强烈的红外辐射信号。     

La/Y掺杂二氧化硅膜的制备及其对染料废水的分离性能研究

以1,2-双(三乙氧基硅基)乙烷(BTESE)为前驱体,采用溶胶-凝胶法制备出完整无缺陷的La/Y掺杂二氧化硅膜.采用TG、FTIR、XRD和SEM等手段表征了La/Y掺杂溶胶凝胶的性质、膜的形貌特征和热稳定性.考察了不同La/Y掺杂比和焙烧温度条件下制备的二氧化硅膜对正电荷染料结晶紫、负电荷染料刚果红等染料废水的分离性能.研究结果表明,与纯BTESE-SiO_2膜相比,La/Y掺杂SiO2膜的分离性能有所提高.La/Y为50/50(摩尔比)、焙烧温度为300℃的合成条件下所制备的La50Y50-SiO2膜对染料废水分离性能最佳.在初始质量浓度为5mg/L的结晶紫溶液和20mg/L的刚果红溶液分离过程中,该膜的渗透通量都高于5.0L/(m~2·h),对染料分子的截留率为100%.该膜对负电荷染料刚果红的分离性能优于其对正电荷染料结晶紫的分离性能.在膜分离染料废水过程中,存在分子筛分和静电吸附的协同分离机制.此外,La/Y掺杂二氧化硅膜还表现出优异的耐盐性,表明该膜可用于高盐染料废水处理.     

Polarization-insensitive electroabsorption by use of quantum well interdiffusion

A paraboliclike quantum well structure can be used to produce polarization-insensitive waveguide type modulators. We propose the use of interdiffusion of AlGaAs/GaAs quantum wells to achieve the parabolic well shape. Criteria to achieve the paraboliclike quantum wells by interdiffusion are discussed. The theoretical results indicate that interdiffused quantum wells can produce equal eigenstate spacing, polarization insensitive Stark shifts, and modulation similar to an ideal parabolic quantum well. Three procedures are also proposed to develop polarization-insensitive on and off states in paraboliclike interdiffused quantum wells. The modulation depth is compatible with that of the measured parabolic quantum wells. For diffused quantum wells one can take advantage of using an as-grown rectangular quantum well with postgrowth thermal processing. These features demonstrate that an interdiffused quantum well structure can be used to produce a polarization-insensitive electroabsorptive modulator.     

Modeling the Optical Constants of Diamonds from 0.06 to 30 eV

The optical properties of diamonds are modeled over a wide spectral range with the modified Adachi's model. Model parameters were estimated by use of the acceptance-probability-controlled simulated annealing algorithm. The employed model is quite flexible, as it uses an adjustable broadening function at each critical point. The broadening function can vary over a range of functions with similar kernels but different wings, so that extended absorption tails inherent to the conventional Lorentzian broadening can be eliminated. Good agreement with the experimental data is obtained in the entire investigated range. The obtained relative rms error for the real part of the index of refraction equals 4.7%, whereas for the imaginary part of the index-of-refraction relative rms error is 3.6%.     

The discovery of biomarkers for type 2 diabetic nephropathy by serum proteome analysis

Diabetic nephropathy (DN) is a serious kidney complication of diabetes, and constitutes the leading cause of end-stage renal disease. The earliest clinical evidence of DN is microalbuminuria, a term which refers to the appearance of small but abnormal amounts of albumin in the urine. However, screening methods for DN, such as biomarker assays, are yet to be developed for type 2 DN. In the present study, in an attempt to identify the biomarkers for initial diagnoses of type 2 DN, the protein profiles of human sera collected from 30 microalbuminuric type 2 diabetic patients were compared with those collected from 30 normoalbuminuric type 2 diabetic patients, via 2-DE. As a result, a total of 18 spots were determined to have different protein levels in the microalbuminuric patients. Twelve spots had lower protein levels of approximately 50%, and the other six had higher levels of approximately 100-300% as compared to the spots of normoalbuminuric patients. These spots were identified with ESI-Q-TOF (ESI-quadrupole-TOF) MS. Among the identified proteins, vitamin D-binding protein (DBP) and pigment epithelium-derived factor (PEDF) were verified by Western blotting. The results of this study indicate that the DBP may be employed as diagnostic and monitoring biomarkers of type 2 DN, contingent on further study into the matter.     

基于网络内部安全防护的研究

网络安全防护体系是一个由外至内的多层次防御体系结构,分为边界安防和内部安防两大部分.阐述了网络内部安防中对于主机和客户端的安全防护问题.     

单相自励恒压异步发电机稳态电压调整率的仿真计算

应用双旋转磁场理论，对一种新型单相自励恒压异步发电机进行理论分析，并提出用多次迭代算法对发电机组的稳态电压调整率进行仿真计算的方法。