- 贾晓红;王人成;张明;李小兵;
This study relates the gait asymmetry, residual limb comfort, and energy cost during walking and identifies a compensating pattern for the trans-tibial amputees when the prostheses are misaligned. One male subject with a trans-tibial amputation volunteered for the study. The knee joint moments at the pros-thetic side, the phase symmetry index, and the interface pressures were discussed under three sagittal alignment settings. The results show that the subject changes the knee joint moment, gait symmetry, and interface pressure with a misaligned prosthesis to improve his comfort and movement during walking. A high-quality liner reduces the gait sensitivity to misalignment and enhances the amputee’s ability to com-pensate for misalignment. Since different people have different compensation patterns, more cases will be studied in future work.
2008年05期 581-586页 [查看摘要][在线阅读][下载 293K] [下载次数：33 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] <正>As the 2008 Beijing Olympic Games draw near, Tsinghua faculty and students are contributing their time and ef-forts in various ways to support the successful organization of events, to perform related research, and to provide volunteer services.
2008年05期 586页 [查看摘要][在线阅读][下载 45K] [下载次数：19 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] - 肖若富;王正伟;罗永要;
Fatigue and cracks have occurred in many large hydraulic turbines after they were put into pro-duction. The cracks are thought to be due to dynamic stresses in the runner caused by hydraulic forces. Computational fluid dynamics (CFD) simulations that included the spiral case, stay vane, guide vane, runner vane, and draft tube were run at various operating points to analyze the pressure distribution on the runner surface and the stress characteristics in the runner due to the fluid-structure interactions (FSI). The dynamic stresses in the Francis turbine runner at the most dangerous operating point were then analyzed. The results show that the dynamic stresses caused by the hydraulic forces during off-design operating points are one of the main reasons for the fatigue and cracks in the runner blade. The results can be used to optimize the runner and to analyze other critical components in the hydraulic turbine.
2008年05期 587-592页 [查看摘要][在线阅读][下载 598K] [下载次数：190 ] |[网刊下载次数：0 ] |[引用频次：42 ] |[阅读次数：0 ] - 刘成;周兆英;付旭;
This paper presents a Kalman filter to effectively and economically determine the Euler angles for micro aerial vehicles (MAVs), whose size and payload are severely limited. The filter uses data from a series of micro-electro mechanical system sensors to determine the selected 3 variables of the direction cosine matrix and the bias of the rate gyro sensors as state elements in a dynamic model, with the gravitational acceleration to build a measurement model. For high speed maneuvers, rigid motion equations are used to correct the measurements of the gravitational acceleration. The filter is designed to automatically tune its gain based on the dynamic system state. Simulations indicate that the Euler angles can be determined with standard deviations less than 3°. The algorithm was successfully implemented in a miniature attitude meas-urement system suitable for MAVs. Aerobatic flights show that the attitude determination algorithm works effectively. The attitude determination algorithm is effective and economical, and can also be applied to bi-onic robofishs and land vehicles, whose size and payload are also greatly limited.
2008年05期 593-597页 [查看摘要][在线阅读][下载 360K] [下载次数：81 ] |[网刊下载次数：0 ] |[引用频次：13 ] |[阅读次数：0 ] - 罗歆;陈永;沈厚发;
A two-dimensional finite element model was used to analyze the thermal and mechanical behavior during solidification of the strand in a continuous bloom casting mold. The coupled heat transfer and defor-mation were analyzed to simulate the formation of the air gap between the mold and the strand. The model was used to investigate the influence of mold taper on the temperature and stress distributions in the strand. The results show that the air gap mainly forms around the strand corner, causing a hotter and thinner solidi-fying shell in this region. The mold taper partially compensates for the strand shell shrinkage and reduces the influence of the air gap on the heat transfer. The mold taper compresses the shell and changes the stress state around the strand corner region. As the strand moves down into the mold, the mold constraint causes compressive stress beneath the corner surface, which reduces the hot tear that forms on the strand.
2008年05期 598-604页 [查看摘要][在线阅读][下载 650K] [下载次数：71 ] |[网刊下载次数：0 ] |[引用频次：6 ] |[阅读次数：0 ] - 刘亚男;刘应华;岑章志;
This paper introduces a meshless method based on Daubechies (DB) wavelets for 2-D elastic problems. The scaling and wavelet functions of the DB wavelet are used as basis functions to approximate the unknown field functions, so there is no need to construct costly shape functions as in the finite element method (FEM) and other meshless methods. In addition, the properties of the DB wavelets facilitate imple-mentation of the method. The new method is used to analyze the elastic problem of a plain plate with a circle hole, and the numerical results agree well with the FEM. This method is effective and can be extended to solve complicated two or three dimensional problems.
2008年05期 605-608页 [查看摘要][在线阅读][下载 132K] [下载次数：61 ] |[网刊下载次数：0 ] |[引用频次：8 ] |[阅读次数：0 ] -
<正>The annual Advisory Board meeting of Tsinghua University's School of Economics and Management (SEM) was held at the Main Building of Tsinghua University on August 8,2008. At the meeting, Professor Qian Yingyi, Dean of Tsinghua SEM reported the significant progress the School has made on student, faculty, and SEM's interna-tionalization process during the past year. The board members held discussion regarding further development of Tsinghua SEM.
2008年05期 608页 [查看摘要][在线阅读][下载 45K] [下载次数：10 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] - 董岚枫;钟约先;马庆贤;袁朝龙;马力深;
A series of thermodynamics experiments were used to optimize the hot forging process of 20SiMn low-carbon alloy steel. A dynamic recrystallization and grain growth model was developed for the 20SiMn steel for common production conditions of heavy forgings by doing a nonlinear curve fit of the experiment data. Optimized forging parameters were developed based on the control of the dynamic recrystallization and the MnS secondary phase. The data shows that the initial grain size and the MnS secondary phase all affect the behavior of the 20SiMn dynamic recrystallization and grain growth.
2008年05期 609-613页 [查看摘要][在线阅读][下载 577K] [下载次数：117 ] |[网刊下载次数：0 ] |[引用频次：23 ] |[阅读次数：0 ] - 付旭;周兆英;熊威;郭奇;
Small unmanned air vehicles (UAVs) can be used for various kinds of surveillance and data collec-tion missions. The UAV flight control system is the key to a successful mission. This paper describes a low-cost micro-electro mechanical system-based flight control system for small UAVs. The integrated hard-ware flight control system weighs only 24 g. The system includes a highly-integrated wireless transmission link, which is lighter than traditional links. The flight control provides altitude hold control and global posi-tioning system navigation based on gain scheduling proportional-integral-derivative control. Flight tests to survey the grass quality of a large lawn show that the small UAV can fly autonomously according to a series of pre-arranged waypoints with a controlled altitude while the wireless video system transmits images of the surveillance target to a ground control station.
2008年05期 614-618页 [查看摘要][在线阅读][下载 293K] [下载次数：155 ] |[网刊下载次数：0 ] |[引用频次：6 ] |[阅读次数：0 ] - 张宜静;徐永忠;李志忠;李洁;吴甦;
This study focuses on the influence of the monitoring method and control complexity on the opera-tor performance in manually controlled spacecraft rendezvous and docking (RVD). Two one-factor experi-ments were designed on a simulated RVD system. One examined the video guidance and periscope moni-toring methods, and the other examined three control complexity levels using one-axis RVD control, two-axis RVD control, and three-axis RVD control. Eighteen male volunteers aged 22-35 participated in the ex-periments. The results show that the RVD operating time increases with control complexity. Based on the operators’ findings, the two-axis control is the easiest. The monitoring method has no significant influence on failure rate with the low complexity using one-axis RVD control.
2008年05期 619-624页 [查看摘要][在线阅读][下载 448K] [下载次数：59 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - 张飞舟;曹学军;杨东凯;
A genetic algorithm (GA) and a hybrid genetic algorithm (HGA) were used for optimal scheduling of public vehicles based on their actual operational environments. The performance for three kinds of ve-hicular levels were compared using one-point and two-point crossover operations. The vehicle scheduling times are improved by the intelligent characteristics of the GA. The HGA, which integrates the genetic algo-rithm with a tabu search, further improves the convergence performance and the optimization by avoiding the premature convergence of the GA. The results show that intelligent scheduling of public vehicles based on the HGA overcomes the shortcomings of traditional scheduling methods. The vehicle operation man-agement efficiency is improved by this essential technology for intelligent scheduling of public vehicles.
2008年05期 625-631页 [查看摘要][在线阅读][下载 152K] [下载次数：173 ] |[网刊下载次数：0 ] |[引用频次：18 ] |[阅读次数：0 ] - 姚丽亚;关宏志;严海;
Traditional trip generation forecasting methods use unified average trip generation rates to deter-mine trip generation volumes in various traffic zones without considering the individual characteristics of each traffic zone. Therefore, the results can have significant errors. To reduce the forecasting error pro-duced by uniform trip generation rates for different traffic zones, the behavior of each traveler was studied instead of the characteristics of the traffic zone. This paper gives a method for calculating the trip efficiency and the effect of traffic zones combined with a destination selection model based on disaggregate theory for trip generation. Beijing data is used with the trip generation method to predict trip volumes. The results show that the disaggregate model in this paper is more accurate than the traditional method. An analysis of the factors influencing traveler behavior and destination selection shows that the attractiveness of the traffic zone strongly affects the trip generation volume.
2008年05期 632-635页 [查看摘要][在线阅读][下载 59K] [下载次数：109 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - 王跃建;宾洋;李克强;
This paper presents a model matching control (MMC) method based on the sliding mode control (SMC) method for longitudinal acceleration tracking control in a vehicular stop-and-go cruise control system. The nonlinearity of the vehicle acceleration response at low speeds was analyzed to develop a transfer func-tion model of the vehicle longitudinal dynamics using the least-mean-square system identification technique. This transfer function was then used to design the MMC controller, including an SMC feedback compensator. The system combines the advantages of the two control methods with robust control and rapid response. Simulations show that the controller enhances the rapid trackability to the vehicle acceleration and improves the system’s robustness at low speeds compared with conventional PID MMC controllers.
2008年05期 636-643页 [查看摘要][在线阅读][下载 198K] [下载次数：130 ] |[网刊下载次数：0 ] |[引用频次：12 ] |[阅读次数：0 ] - 黄谦;石京;
Road maintenance work brings costs to the government and delays to users. The setting up of work zones often leads to severe congestion during peak hours, especially in busy urban areas. A road maintenance delay model is presented here that includes consideration of excessive traffic flow and non-motorists. A trial-and-error method is used to find the optimal work zone length and the best work starting time to minimize the total cost of maintenance and delays. A numerical example with a sensitivity analysis is also given. The results show that optimal starting time is not sensitive to the flow speed and the increase of work zone speeds sharply reduces the total cost when the road is congested.
2008年05期 644-650页 [查看摘要][在线阅读][下载 432K] [下载次数：121 ] |[网刊下载次数：0 ] |[引用频次：13 ] |[阅读次数：0 ] - 应习文;石京;
The paper analyzes the equity of road resources distribution in urban areas by modeling the competitive relationship among different road users. A logistic model is used to describe the development of different traffic modes in the transportation network. The system is similar to the species competition model, so a two-species model is used to analyze the relationship between users based on the stability of the equi-librium points. The Lotka-Volterra model is then used to describe the multi-species cases with numerical examples, showing that this model can describe the effects of the road space distribution on the competitive user relationships. Policy makers must ensure the equity of road resources distribution so that each urban transportation mode is properly developed for sustainable social development.
2008年05期 651-659页 [查看摘要][在线阅读][下载 417K] [下载次数：109 ] |[网刊下载次数：0 ] |[引用频次：19 ] |[阅读次数：0 ] <正>Tsinghua Professor and Turing Award Winner Andrew Chi-chih Yao delivered a speech on July 7, 2008, to the Tsinghua Forum entitled "China's Road toward the Turing Award".
2008年05期 659页 [查看摘要][在线阅读][下载 95K] [下载次数：16 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] - 邱颖;陆化普;王海威;
Currently applied prediction methods of regional freight traffic and freight ton-kilometer forecasting were analyzed using typical Chinese regional goods transportation characteristics. The review of prediction methods showes that practical planning experts tend to apply the traditional methods which are easier to implement. The comparison also demonstrates that a combination of traditional methods is more effective than the simple models for practical planning. Research using the statistical data for the Yangtze Delta, Pearl River Delta, and Bohai Rim areas shows that ignoring differences between transport modes impacts the pre-diction accuracy. The four main transport modes suit different methods. The results show that the power model is better for railways, and the linear model is better for highways and waterways. Thus a combined model gives better results for all modes. The results for regional systems can be generalized to national transportation systems.
2008年05期 660-668页 [查看摘要][在线阅读][下载 815K] [下载次数：382 ] |[网刊下载次数：0 ] |[引用频次：31 ] |[阅读次数：0 ] - 张君;冷冰;
This paper presents an experimental study of the possibility of transition from multiple macro-cracking to multiple micro-cracking in cementitious composites. Conventional polyvinyl alcohol fiber reinforced cementitious composites normally exhibit macroscopic strain-hardening and multiple cracking af-ter the first cracks appear. However, the individual crack width at the saturated stage is normally 60 to 80 μm. In the current study, the effect of fine aggregate size on the cracking performance, especially the in-dividual crack width in the strain-hardening stage was studied by bending tests. The results show that the individual crack widths can be reduced from 60-80 μm to 10-30 μm by modifying the particle size of the fine aggregates used in the composites.
2008年05期 669-673页 [查看摘要][在线阅读][下载 895K] [下载次数：60 ] |[网刊下载次数：0 ] |[引用频次：20 ] |[阅读次数：0 ] - 任爱珠;陈驰;罗元;
A virtual reality system was developed to simulate emergency evacuations during fires. The spreading of the flame and smoke in the virtual fire was modeled based on numerical fire simulations, so that the conditions are similar to real life. A multi-grid, multi-base-state database model was used to overcome the disadvantages of traditional smoke spreading simulations. Textured images and particle systems provide visualization of the flame and smoke. The system immerses the user in a virtual environment with detailed interactions between the users and the virtual environment. The system can show which evacuation methods are effective for building safety evaluations.
2008年05期 674-680页 [查看摘要][在线阅读][下载 178K] [下载次数：326 ] |[网刊下载次数：0 ] |[引用频次：26 ] |[阅读次数：0 ] <正>A commencement ceremony to award graduate degrees was held in the Auditorium at Tsinghua University on July 5, 2008. There were 1022 doctorates and 3282 master's degrees awarded at the ceremony.
2008年05期 680页 [查看摘要][在线阅读][下载 77K] [下载次数：11 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] - 王静峰;李国强;
This paper presents a simplified beam design method for semi-rigid composite frames with vertical loading at the serviceability limit state. Equations were developed to determine the deflections of the com-posite beam allowing for both joint flexibility and beam sectional properties, along with a formula for the connection secant stiffness. The equations for the connection stiffness are more accurate than previous equations used because it considers the beam-to-column stiffness ratio and the beam-to-connection stiffness ratio. The equations were validated by the experimental results for two semi-rigid composite frames. The equations agree well with the experimental data because they take into account the actual beam-to-column connections and the composite action between the steel beam and the concrete slab.
2008年05期 681-688页 [查看摘要][在线阅读][下载 234K] [下载次数：52 ] |[网刊下载次数：0 ] |[引用频次：5 ] |[阅读次数：0 ] <正>Born in 1977, Dr. Nieng Yan is currently Tsinghua University's youngest professor. As a Tsinghua undergraduate, she developed a strong interest in science and was deeply influenced by Beijing's unique civil milieu. After receiv-
2008年05期 688页 [查看摘要][在线阅读][下载 68K] [下载次数：16 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] - 吴璟;郑思齐;
Housing liquidity measures the ability to convert housing to cash as an important characteristic of housing stock. A simple model of buyer offers’ distributions was used to theoretically explore the determi-nants of housing liquidity in a search process. An empirical ordinary least squares model of the time-on-market was developed using data collected in four Chinese cities (Beijing, Shanghai, Guangzhou, and Shenzhen). The results show that in these four Chinese cities, market maturity dominates the variation of housing liquidity, with the effects of housing characteristics, seller’s search cost, search strategy, and market conditions being less significant to the time-on-market equation. These empirical results indicate that the slow turn-over of housing stock may constrain the overall level of housing liquidity in major Chinese cities.
2008年05期 689-695页 [查看摘要][在线阅读][下载 96K] [下载次数：143 ] |[网刊下载次数：0 ] |[引用频次：4 ] |[阅读次数：0 ] <正>Vice President Meng Liqiu of Technical University of Munich (TUM) visited Tsinghua University on July 7, 2008. Tsinghua Vice President Kang Kejun had a discussion with Professor Meng. VP Kang briefed Professor Meng on
2008年05期 695页 [查看摘要][在线阅读][下载 18K] [下载次数：11 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] - 李春秋;李克非;陈肇元;
The influential depth of moisture transport in a concrete surface subject to drying-wetting cycles was analyzed numerically. The moisture transport was described by a diffusion model with different diffusivi-ties for drying and wetting. A finite difference scheme was developed to solve the partial differential equations. The influential depth was then investigated numerically for initially saturated and unsaturated concretes ex-posed to drying-wetting actions in marine environments using an equilibrium time ratio concept. The equilib-rium time ratio was calculated numerically for a saturated condition and the moisture influential depth is shown to be a linear function of the square root of the drying time. However, this equilibrium time ratio does not exist for an unsaturated condition and the moisture influential depth depends on the initial saturation as well as the drying-wetting time ratio. The results indicate that this model gives more realistic predictions of moisture transport of in situ structural concrete and its durability.
2008年05期 696-701页 [查看摘要][在线阅读][下载 343K] [下载次数：131 ] |[网刊下载次数：0 ] |[引用频次：12 ] |[阅读次数：0 ] - 柯永建;刘新平;王守清;
The feasibility study of a public-private partnership (PPP) project is regarded as one of the critical factors for successful implementation, but unfortunately the common financial evaluation methods currently used only represent the benefits of the private sector. There is, therefore, an urgent need to develop an eq-uitable financial evaluation method for PPP projects. This paper presents a comprehensive literature review that examines international practices. An equitable financial evaluation method was then developed taking into account the inherent characteristics of PPP projects using six separate indicators and Monte Carlo simulations. The result for a bridge project in Romania shows that the method combines the viewpoints of all the relevant stakeholders to achieve an equitable financial evaluation of PPP projects.
2008年05期 702-707页 [查看摘要][在线阅读][下载 186K] [下载次数：965 ] |[网刊下载次数：0 ] |[引用频次：85 ] |[阅读次数：1 ] - 唐方勤;任爱珠;
A comprehensive description of the key factors affecting evacuations at fire scenes is necessary for accurate simulations. An agent-based simulation model which incorporates the fire scene and the building geometry is developed using a fire dynamics simulator (FDS) based on the computational fluid dynamics and geographic information system (GIS) data to model the occupant response. The building entities are gener-ated for FDS simulation while the spatial analysis on GIS data represents the occupant’s knowledge of the building. The influence of the fire is based on a hazard assessment of the combustion products. The agent behavior and decisions are affected by environmental features and the fire field. A case study demonstrates that the evacuation model effectively simulates the coexistence and interactions of the major factors includ-ing occupants, building geometry, and fire disaster during the evacuation. The results can be used for the assessments of building designs regarding fire safety.
2008年05期 708-714页 [查看摘要][在线阅读][下载 383K] [下载次数：144 ] |[网刊下载次数：0 ] |[引用频次：12 ] |[阅读次数：0 ] <正>President Charles Vest of the National Academy of Engineering in the United States visited Tsinghua University on June 26,2008. Tsinghua Vice President Kang Kejun exchanged ideas with Dr. Vest on research, education, and
2008年05期 714页 [查看摘要][在线阅读][下载 15K] [下载次数：13 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] - 杜鹏飞;
This paper presents a study of the middle route of the South-North Water Diversion Project. The middle route runs through the Northern China plain, where the water shortages are the most severe. There is not only a shortage of water for human usage, but also a shortage of ecological water. Although the cur-rent plan for the middle route is strictly focused on supplying water for residential and industrial use, the water can also potentially be used for ecological purposes. This paper evaluates the potential ecological benefits that can be brought to the fragile ecology in northern China by the middle route, in addition to the water supplied to residences and industry. The study describes ecological benefits of the middle route pro-ject, such as mitigation of groundwater extraction in the region and positive influences on the climate, the ecological uses of the middle route project itself, such as creating artificial niches along the channel and di-rectly using the channel for ecological purposes, and the ecological uses of the water along the middle route, such as diversion of the water into river channels that have suffered from drought conditions for decades.
2008年05期 715-719页 [查看摘要][在线阅读][下载 109K] [下载次数：87 ] |[网刊下载次数：0 ] |[引用频次：7 ] |[阅读次数：0 ] - 王华;逄勇;丁玲;刘明源;庄红红;
Measured field data was used to analyze the factors which influence the transparency of the Nei River and to develop a multi-factor correlation for the transparency. A 2-D unsteady model which coupled analyses of the water flow, water quality, suspended sediments, and Chl-a was developed to simulate the changes in the transparency for various conditions. The model was then used to forecast the transparency of the Nei River. The suspended sediment concentration (SSC) was found to be the most important factor in-fluencing the transparency, with high concentrations of CODMn and Chl-a also reducing the transparency to some extent. The transparency model is stable and precise, with relative errors between measured and calculated values of less than 15%. With the environmental scheduling schemes, the Nei River transparency can be significantly improved with a mean transparency in high-water years of 69.3 cm, normal-water years of 70.8 cm, and low-water years of 69.8 cm.
2008年05期 720-729页 [查看摘要][在线阅读][下载 1089K] [下载次数：42 ] |[网刊下载次数：0 ] |[引用频次：7 ] |[阅读次数：0 ] - 宋凤霞;于燕梅;陈健;
Chemical complexation, in which certain metal ions (especially Ag+ and Cu+) reversibly and selec-tively complex olefin isomers, was used to separate 1-hexene from a mixture of internal hexenes as an at-tractive alternative to traditional distillation. Several potential reactive extractants were investigated for their selectivity of both 1-hexene to 2-hexene and 1-hexene to 3-hexene. With 3 mol/L AgNO3-N-methyl-pyr-rolidone (NMP) solution as extractant, the selectivity of 1-hexene to 3-hexane was increased to about 2.0 and the selectivity of 1-hexene to 2-hexene reached 1.5. Both the raffinate phase and the extracted phase were analyzed using a gas chromatograph equipped with a flame ionization detector and a 50-m capillary column. The experimental results show that the silver nitrate NMP solution has the better selectivity than other reac-tive extractions.
2008年05期 730-735页 [查看摘要][在线阅读][下载 323K] [下载次数：35 ] |[网刊下载次数：0 ] |[引用频次：6 ] |[阅读次数：0 ] - 高楠;翁文国;马伟;倪顺江;黄全义;袁宏永;
Old towns like Lijiang have enormous historic, artistic, and architectural value. The buildings in such old towns are usually made of highly combustible materials, such as wood and grass. If a fire breaks out, it will spread to multiple buildings, so fire spreading and controlling in old towns need to be studied. This paper presents a fire spread model for old towns based on cellular automaton. The cellular automaton rules were set according to historical fire data in empirical formulas. The model also considered the effects of cli-mate. The simulation results were visualized in a geography information system. An example of a fire spread in Lijiang was investigated with the results showing that this model provides a realistic tool for predicting fire spread in old towns. Fire brigades can use this tool to predict when and how a fire spreads to minimize the losses.
2008年05期 736-740页 [查看摘要][在线阅读][下载 596K] [下载次数：93 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] -
<正>Tsinghua Science and Technology (Tsinghua Sci Technol), a comprehensive academic journal sponsored by Tsinghua University, is published bimonthly. This journal aims at presenting the up-to-date scientific achievements
2008年05期 741页 [查看摘要][在线阅读][下载 808K] [下载次数：11 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] 下载本期数据