科创中国

根据预期假说,本文对我国利率期限结构的远期利率预测作用进行了经验分析.结果表明,我国利率期限结构存在明显的时变溢价特征,这可以解释利率期限结构中的"预期之谜".经期限溢价修正后,利率期限结构所隐含的远期利率包含了大量未来即期利率变化的信息,而且无法拒绝预期理论.这对中央银行观察金融市场对经济的预期和未来利率走势,判断实际货币政策态势,具有重要的参考价值,并为我国推进利率市场化、实现通过利率价格工具调整开展间接调控的货币政策模式转型,提供了可靠的理论依据.

Blade vibration failure is one of the main failure modes of compressor wheel of turbocharger for vehicle application.The existing models for evaluating the reliability of blade vibration of compressor wheel are static,and can not reflect the relationship between the reliability of compressor wheel with blade vibration failure mode and the life parameter.For the blade vibration failure mode of compressor wheel of turbocharger,the reliability evaluation method is studied.Taking a compressor wheel of turbocharger for vehicle application as an example,the blade vibration characteristics and how they change with the operating parameters of turbocharger are analyzed.The failure criterion for blade vibration mode of compressor wheel is built with the Campbell diagram,and taking the effect of the dispersity of blade natural vibration frequency and randomness of turbocharger operating speed into account,time-dependent reliability models of compressor wheel with blade vibration failure mode are derived,which embody the parameters of blade natural vibration frequency,turbocharger operating speed,the blade number of compressor wheel,life index and minimum number of resonance,etc.Finally,the rule governing the reliability and failure rate of compressor wheel and the method for determining the reliable life of compressor with blade vibration is presented.A method is proposed to evaluate the reliability of compressor wheel with blade vibration failure mode time-dependently.

The existing researches of the evaluation method of ride comfort of vehicle mainly focus on the level of human feelings to vibration. The level of human feelings to vibration is influenced by many factors, however, the ride comfort according to the common principle of probability and statistics and simple binary logic is unable to reflect these uncertainties. The random fuzzy evaluation model from people subjective response to vibration is adopted in the paper, these uncertainties are analyzed from the angle of psychological physics. Discussing the traditional evaluation of ride comfort during vehicle vibration, a fuzzily random evaluation model on the basis of annoyance rate is proposed for the human body's subjective response to vibration, with relevant fuzzy membership function and probability distribution given. A half-car four degrees of freedom suspension vibration model is described, subject to irregular excitations from the road surface, with the aid of software Matlab/Simulink. A new kind of evaluation method for ride comfort of vehicles is proposed in the paper, i.e., the annoyance rate evaluation method. The genetic algorithm and neural network control theory are used to control the system. Simulation results are obtained, such as the comparison of comfort reaction to vibration environments between before and after control, relationship of annoyance rate to vibration frequency and weighted acceleration, based on ISO2631/1(1982), ISO 2631–1(1997) and annoyance rate evaluation method, respectively. Simulated assessment results indicate that the proposed active suspension systems prove to be effective in the vibration isolation of the suspension system, and the subjective response of human being can be promoted from very uncomfortable to a little uncomfortable. Furthermore, the novel evaluation method based on annoyance rate can further estimate quantitatively the number of passengers who feel discomfort due to vibration. A new analysis method of vehicle comfort is presented.

Direct drive servovalves are mostly restricted to low flow rate and low bandwidth applications due to the considerable flow forces.Current studies mainly focus on enhancing the driving force,which in turn is limited to the development of the magnetic material.Aiming at reducing the flow forces,a novel rotary direct drive servovalve(RDDV)is introduced in this paper.This RDDV servovalve is designed in a rotating structure and its axially symmetric spool rotates within a certain angle range in the valve chamber.The servovalve orifices are formed by the matching between the square wave shaped land on the spool and the rectangular ports on the sleeve.In order to study the RDDV servovalve performance,flow rate model and mechanical model are established,wherein flow rates and flow induced torques at different spool rotation angles or spool radiuses are obtained.The model analysis shows that the driving torque can be alleviated due to the proposed valve structure.Computational fluid dynamics(CFD)analysis using ANSYS/FLUENT is applied to evaluate and validate the theoretical analysis.In addition,experiments on the flow rate and the mechanical characteristic of the RDDV servovalve are carried out.Both simulation and experimental results conform to the results of the theoretical model analysis,which proves that this novel and innovative structure for direct drive servovalves can reduce the flow force on the spool and improve valve frequency response characteristics.This research proposes a novel rotary direct drive servovalve,which can reduce the flow forces effectively.

Layered organic-inorganic hybrids containing bilayer perovsikte (R-NH3)2(CH3NH3)Pb2I7 (where R=C12H25,C6H5C2H4) were synthesized by reactions in solution. The influences of the solvents and the reactant ratio on the structures of the products were investigated. The structures and the properties of the hybrids were characterized using X-ray diffraction (XRD) and ultraviolet and visible (UV) adsorption spectra. For comparing with the bilayer perovskite hybrids in structure and band gap magnitude, the hybrids containing monolayer perovskite (R-NH3)2PbI4 were also synthesized and characterized. The results demonstrate that the thickness of inorganic layer has obvious effect on the tunneling magnitude of the band gap but the organic part can be micro actuator of band gap.

Many attentions for structural synthesis are paid to planar linkages and parallel mechanisms, while design novel pyramid deployable truss structure(PDTS) of satellite SAR mainly depends on experience of designer. To design novel configuration of PDTS, a two-step topology structure synthesis and analysis approach is proposed. Firstly, a conceptual configuration of PDTS is synthesized. Weighted graph and weighted adjacency matrix are established to realize topological description for PDTS. Graph properties are then summarized to distinguish differentia between PDTS and other type structures. According to graph properties, a procedure for synthesis conceptual configuration of PDTS is presented. Secondly, join relationship of components in a PDTS is analyzed. Kinematic chain and corresponding incidence/adjacency matrix are employed to analyze join relationship of PDTS. Properties and simplified rules of kinematic chain are extracted to construct kinematic chain. A procedure for construction kinematic chain of PDTS is then established. Finally, with this two-step approach all 11 rectangular pyramid deployable structures whose folded state is planar are discovered and their kinematic chains are constructed. Based on synthesis results, a novel deployable support structure for satellite SAR is designed. The proposed research can be applied to obtain some novel PDTSs, which is of great importance to design some novel deployable support structures for satellite SAR antenna.

目的评价胃镜下氩离子凝固术联合质子泵抑制剂奥美拉唑治疗Barrett食管(BE)的长期临床疗效.方法对2009年1月~2011年1月我院胃镜室检查并经病理证实的Barrett食管患者59例,根据患者意愿分为两组.对照组31例,给予奥美拉唑20mg口服,每日1次;实验组在胃镜下行氩离子凝固术,术后给予奥美拉唑20mg口服,每日1次.两组患者进行随访.于术后3、6和12个月时复查胃镜,评价Barrett食管复发情况.结果治疗后3个月时对照组临床症状缓解例数为15例,缓解率为48.4%,实验组有缓解例数为22例,缓解率为78.6%,实验组明显高于对照组(Xz=5.72,P=0.01).对照组治疗前症状评分为(1.82±0.51)分,治疗后为(1.34±0.66)分;实验组治疗前症状评分为(1.83±0.46)分,治疗后为(0.81±0.28)分,实验组症状缓解明显好于对照组(t=3.94,P〈0.01).术后主要不良反应为胸骨后不适8例(28.6%),黏膜下气肿4例(14.3%)和发热3例(10.7%);随访12个月,实验组累及复发6例(6/28),累及复发率为21.4%.结论胃镜下氩离子凝固术联合奥美拉唑治疗Barrett安全可靠,短期疗效确切,长期随访存在一定的复发率.

分析专业图书馆实现知识服务转型的4个主要方面及对图书馆人员结构的需求,包括建设多元化数字资源保障体系、探索面向专业领域的知识服务模式、试验开展集成化知识环境建设、创建柔性灵活的团队与协作机制.结合以国家科技文献中心成员单位为代表的专业图书馆人员队伍结构,分析其人员队伍状况,阐明专业图书馆人员结构与未来发展存在业务布局、专业能力、信息技术水平、组织管理体制等方面的差距.

针对NRA算法和BPA算法查询效率不高、重复访问数据的问题,提出了一种基于三维分档布鲁姆过滤器表(TF)的Top-κ查询算法(TKBFP).该算法使用TF对数据进行处理,以较低的误判率获得较高的访问效率并降低了内存消耗,利用最优位置索引策略,避免重复访问数据对象.对TKBFP算法进行了严格的语义定义,推导出每一维BF中需要的哈希函数个数;以自主开发的Java程序为仿真平台,对TKBFP算法进行了试验,并对算法执行效率和存储性能进行评价.试验结果表明,该算法能够避免重复访问数据对象,并能以较低的误判率实现大规模数据的高效查询处理.与NRA和BPA相比,当属性列表超过4个时,开销明显降低,适合面向大规模数据的查询处理应用.

采用乙二胺水杨醛sch诳碱配体与水合硝酸铜配位生成了一雁形的双核Cu(II)配合物.产物通过了元素分析、红外光谱及单晶x射线衍射分析等手段的证实.结果表明,该配合物晶体属于单斜晶系,P21/c空间群,晶胞参数为:a=0.8559(14),b=2.3276(4),c=1.1057(18)nm,β=91.360(4)°,V=2.2021(6)nm3,Z=2,Do=1.706g/cm3,M=1130.82,RI=0.0.543,wR2=0.1522;结构分析表明,配合物中存在两种截然不同的Cu(II)配位模式,Cu(1)离子采取四方平面构型,Cu(2)离子却为扭曲八面体几何构型.