三门峡西段村水库泄洪洞—消力池部位黄土岸坡稳定性分析

西段村水库位于黄河支流的涧河上,大坝右岸消力池部位黄土岸坡施工过程中出现失稳变形现象,致使消力池施工被迫停止。为保证安全,需对消力池及上游右坝肩至泄洪洞出口段黄土边坡进行稳定性评价,为此,开展了必要的地质研究工作,并应用计算软件进行了分析计算,提出了针对性的处理措施。本研究成果在工程中的应用,解决了关键性工程地质问题和难题,为节省投资,加快施工进度以及防治地质灾害提供了依据。     

智能机械臂的压电半主动振动控制

以在半主动控制领域具有良好应用前景的压电元件为基础,在受控机械臂上粘贴压电陶瓷(PZT)片,运用基于压电分流阻尼的振动被动控制和基于同步开关阻尼(SSD)技术的半主动控制理论,消耗机械臂振动的机械能,减小结构振动的位移幅度,从而达到振动控制的目的.     

电势滴定法测定溶度积常数 Ksp

以自测或文献报道的六组电势滴定数据，代入本文导出的溶度积常数ＫＳＰ关系式，所得有关的ＫＳＰ值与文献值相符，说明该法具有一定的可靠性，且测试方便，计算简单，本文还用自制的四苯硼根电极为指示电极，以四苯硼钠为滴定剂，利用上法测定和计算了尚未报道的３６种四苯硼盐的深度积常数。     

Performance of energy-aware and link-adaptive routing metrics for ultra wideband sensor networks

Wireless sensor networks are energy constrained since sensors operate with limited battery capacity. Thus, energy consumption is one of the most critical issues in the design of routing protocols. In addition, the link quality needs to be taken into account in the route decision for a wireless multihop network in order to efficiently exploit the inherent spatial diversity. In this paper we consider energy-aware and link-adaptive routing strategies for UWB (Ultra Wide Band) sensor networks. We utilize the ranging capabilities offered by UWB and employ adaptive modulation to take advantage of favorable link conditions. Different routing metrics are proposed based on the availability of sensor node’s location, link quality and next hop battery capacity information. These routing metrics integrate the measure of next hop remaining battery capacity with the throughput performance measures, Maximum Forward Progress (MFP) or Maximum Information Progress (MIP). The effectiveness of these metrics is evaluated in different simulation scenarios in terms of network throughput and lifetime for both random and grid sensor network topologies. Jinghao Xuis a D.Sc. candidate of the Department of Electrical and Computer Engineering at the George Washington University. He received his B.Sc. and M.S. degrees in telecommunication and electrical engineering from the Tianjin University, China, in 1993 and 1996, respectively. From 1996 to 2001, he was with Research Institute of Telecommunication Transmission of Ministry of Information Industry, Beijing, China, and China Wireless Telecommunication Standards group, where he was involved in the standardization of IMT-2000 communication systems for China. His research interests include performance evaluation and modeling of wireless ad hoc networks, Ultra Wide Band systems and multiuser detection techniques. Bojan M. Peric received the B.S. degree in electrical engineering from the University of Belgrade, Belgrade, Serbia and Montenegro in 2001. He is currently working toward the D.Sc. degree in electrical engineering at the George Washington University, Washington, DC. His research interests include wireless communications, with an emphasis on ad hoc networks. Branimir R. Vojcic is a professor in, and a past Chairman of, the Department of Electrical and Computer Engineering at the George Washington University. He has received his Dipl. Ing., M.Sc. and D.Sc. degrees from the University of Belgrade in Serbia and Montenegro in 1980, 1986 and 1989, respectively. His current research interests are in the areas of communication theory, performance evaluation and modeling mobile and wireless networks, mobile internet, code division multiple access, multiuser detection, adaptive antenna arrays, space-time coding and ad-hoc networks. He has also been an industry consultant and has published and lectured extensively in these areas. He co-authored the book: The cdma2000 System for Mobile Communications. Dr Vojcic received NSF CAREER Award in 1995. He is a Senior Member of IEEE, was an Associate Editor for IEEE Communications Letters and is presently an Associate Editor for Journal on Communications and Networks.     

中温联合二甲基二碳酸盐对荔枝原汁品质的影响

该研究比较了二甲基二碳酸盐（Dimethyl Dicarbonate,DMDC）、中温及两者联合处理对荔枝原汁微生物及理化指标的影响。结果表明：荔枝原汁经DMDC或中温单独处理灭菌效果较差,联合处理组残留微生物最少,菌落总数、乳酸菌分别为0.41、0.36 lg CFU/mL,酵母菌和霉菌未检出;与新鲜荔枝汁相比,DMDC处理对荔枝原汁品质无影响,中温及联合处理组抗坏血酸和色泽无明显变化,总酚（总黄酮）分别增加了40.16%（7.16%）、38.01%（4.35%）;铁离子还原能力（清除DPPH自由基能力）分别提高了15.55%（11.85%）、7.61%（3.71%）,说明中温能促进酚类物质的释放,提高抗氧化活性。相关性分析显示,荔枝原汁的∆E与Vc呈负相关,抗氧化活性与总酚、总黄酮呈正相关;聚类热图分析与感官评价表明,联合处理能促进风味物质的释放,且不会造成明显的蒸煮味;联合处理组在4 ℃贮藏21 d的菌落总数均小于100 CFU/mL。综上,中温联合DMDC处理对荔枝原汁微生物有较好的灭菌效果,且对品质无不良影响,4 ℃贮藏期可达21 d,该研究为高品质荔枝原汁产业化提供了科学依据。     

核主泵用动静压波度机械密封机理

核反应堆主泵主轴密封形式多样,动静压结合型波度机械密封是Andritz核主泵主轴密封结构形式,其特征在于密封端面为径向锥度和周向波度的组合.通过对波形几何模型的数学处理,将膜厚变化引起的动压效应和静压效应进行解耦.在层流假设的基础上,基于稳态下二维Reynolds方程,针对核主泵轴封不同工况分别作考虑空化的流体有限元仿真分析,考察参数变化对密封性能的影响,从而揭示出动静压结合型波度机械密封的工作机理.研究表明,动静压结合型波度端面机械密封中,动压和静压效应并不始终同时起作用,在正常工况下主要依靠静压效应承载;而在密封间隙较小或密封出入口压差较小时,因为液膜发生空化,动压效应才起到承载作用,从而保证密封在特殊工况下保持非接触状态,减小碰磨的几率,提高了密封的工作可靠性和使用寿命.     

Encapsulation of MnS Nanocrystals into N,S-Co-doped Carbon as Anode Material for Full Cell Sodium-Ion Capacitors

Sodium-ion capacitors(SICs)have received increasing interest for grid stationary energy storage application due to their affordability,high power,and energy densities.The major challenge for SICs is to overcome the kinetics imbalance between faradaic anode and nonfaradaic cathode.To boost the Na+reaction kinetics,the present work demonstrated a high-rate MnS-based anode by embedding the MnS nanocrystals into the N,S-co-doped carbon matrix(MnS@NSC).Benefiting from the fast pseudocapacitive Na+storage behavior,the resulting composite exhibits extraordinary rate capability(205.6 mAh g−1 at 10 A g−1)and outstanding cycling stability without notable degradation after 2000 cycles.A prototype SIC was demonstrated using MnS@NSC anode and N-doped porous carbon(NC)cathode;the obtained hybrid SIC device can display a high energy density of 139.8 Wh kg−1 and high power density of 11,500 W kg−1,as well as excellent cyclability with 84.5%capacitance retention after 3000 cycles.The superior electrochemical performance is contributed to downsizing of MnS and encapsulation of conductive N,S-co-doped carbon matrix,which not only promote the Na+and electrons transport,but also buffer the volume variations and maintain the structure integrity during Na+insertion/extraction,enabling its comparable fast reaction kinetics and cyclability with NC cathode.     

原子荧光光度法测定水中汞的测量不确定度的评定

文章根据原子荧光光度法，用吉天AFS-820原子荧光光度计测定水样中的总汞，并且分析了主要的测量不确定度来源，即工作曲线不确定度、标准溶液不确定度、测量重复性不确定度和仪器分辨率不确定度，分别量化后加以合成即得总汞的测量不确定度。     

Delayed Polarization Saturation Induced Superior Energy Storage Capability of BiFeO3-Based Ceramics Via Introduction of Non-Isovalent Ions

Electrostatic capacitors are emerging as a highly promising technology for large-scale energy storage applications. However, it remains a significant challenge to improve their energy densities. Here, an effective strategy of introducing non-isovalent ions into the BiFeO₃-based (BFO) ceramic to improve energy storage capability via delaying polarization saturation is demonstrated. Accordingly, an ultra-high energy density of up to 7.4 J cm⁻³ and high efficiency ≈ 81% at 680 kV m⁻¹ are realized, which is one of the best energy storage performances recorded for BFO-based ceramics. The outstanding comprehensive energy storage performance is attributed to inhibiting the polarization hysteresis resulting from generation ergodic relaxor zone and random field, and generating highly-delayed polarization saturation with continuously-increased polarization magnitudes with the electric field of supercritical evolution. The contributions demonstrate that delaying the polarization saturation is a consideration for designing the next generation of lead-free dielectric materials with ultra-high energy storage performance.