High-speed railway technology is a super large and very complex engineering system. The paper introduces the current situation of China railway system, noting that it is very urgent for China to push ahead railway construction, especially, high-speed railway construction by drawing experiences from all around the world and carrying out experiment on our own, thus developing an innovative high-speed railway technological system with Chinese characteristics. Some engineering projects under construction are also cited in the paper.
In the last 20 years of the 19th century, plague prevailed in the world. During this period, Dijkman Christiaan, the Nobel Physiology and Medicine Prize owner, discovered "beriberi" . The Chinese specialists Wu Cunfu and Luo Rulan wrote the composition named "Collection of the Plague" . And the famous scholar Yorsinia discovered the plague bacillus. This article aimed to find out the influence of the foregoing findings in the academic circle. The author further demonstrates the identity of historical beriberi and the plague, and also demonstrates the inner connection between the plague in Chinese Ming and Qing dynasties and that in the period of Edo and Meiji of Japan. The author also analyzes the macro- integrity and micro-regression. Combining the suspicions in the medical history concerning the Chinese and English Encyclopedia, the author gives out his own explanation of the scientific research measures and the complexity of the Chinese Medicine.
Space Medico-Engineering is a newly emerged subject with its own characteristic theoretical system and technological methods. With 40 years′ development and practice of manned space flight in China, it gradually comes into being. This paper briefly introduces its concept, system structure, research content and characteristics.
The first performance of the no -till seeder is to avoid the stalk blockage while seeding. To solve the blockage problem, oversea no-till seeders mostly rely on heavy weight (760-1130 kg/m) or big size. But those seeders are not suitable for Chinese conditions of small land size, small tractor and weak left force (300~600 kg/m), and are expensive as well. After 10 year efforts since 1990, light passive anti-blockage no-till seeders were developed and largely applied to the middle and low yield regions. However, the anti-blockage performance of the seeders is limited, difficult to work in the high yield region. From 1998, 3 types of light and active anti-blockage no-till seeders, strip rotary hoe, strip chopping and power driven disk no- till seeders, have been developed. Those seeders have strong anti-blockage ability, and can directly seed wheat on the heavy maize stalk mulching field. The unit weight is 316~500 kg/m, which can matchdomestic tractors. The price is 1/8 of oversea no-till seeders. From the planting quality test of 3 no-till seeders in 2004~2006, the light active anti-blockage no-till seeders have shown more soil disturbance and power consuming than oversea no-till seeders, but had advantages of wheat emergence, seedling growth and wheat yield. Nearly 20, 000 pieces of the light & high anti- blockage no-till seeders have been applied to the direct seeding wheat in maize stalk mulching field of 400, 000 hm2 in 2006, resulted resources saving, environment protection and farmer benefits increasing.
In this paper, the degradation kinetics of diphenyl ketone and malachite green in water has been studied, including the theoretical analysis of the degradation kinetics of organic compounds in water by using 185nmUV irradiation, analysis of the reaction rate constant and the effect of temperature, concentration, pH and other factors on the reaction rate constant. A chemical kinetic equation is established and the kinetics rule for degradation of diphenyl ketone and malachite green is discussed. The degradation reaction is found to be a pseudo-first order reaction.
Markov Chain Monte Carlo (MCMC) methods, which are popular for estimating parameters uncertainty of hydrologic models, generally converge slowly, and are easy to get stuck in a local optimized region in the parametric space during uncertainty assessment of hydrologic model parameters. In this paper the Parallel Adaptive Metropolis (PAM) algorithm is presented to access the parameters uncertainty of hydrologic models. The PAM algorithm provides an adaptive MCMC sampler to estimate the posterior probability distribution of parameters under Bayesian framework. The performance of the PAM algorithm is greatly improved in the manner of parallel computing. The PAM algorithm is applied to assess the parameter uncertainty of Xinanjiang model using hydrologic data from Shuangpai Reservoir. The case study demonstrates that there is considerable uncertainty about the Xinanjiang model parameters. The hydrograph prediction uncertainty ranges associated with the posterior distribution of the parameters estimates can bracket the observed flows well, but not large, indicating that the method is feasible.
]To meet the cruise missile's air-to-surface attack requirement, specified impact angle guidance law is presented based on line of sight (LOS) information framework. Theoretical analysis proves its property. Considering the missile autopilot's dynamics, a simple engineering version of integrated guidance and control synthesis is deduced to improve performance. Mid-course trajectory characteristic is utilized to obtain smooth and low-delay vertical velocity to calculate trajectory angle. Finally mathematical simulation demonstrates their effectiveness.
The influence of pitch/lag coupling on helicopter air resonance is investigated by the methods of multi- blade coordinates transformation and complex coordinates transfer in this paper. First, helicopter air resonance equations of motion considering pitch/lag coupling is derived, related analysis model and calculation programs are built to study the effect of pitch/lag coupling on helicopter air resonance through the eigenvalue of the system. Second, through the eigenvector and the analysis of the approximate expression of mutual excitation of different degrees of freedom, the explanations of the helicopter air resonance considering pitch/lag coupling are explicated. The results indicated that the positive pitch/lag coupling can restrain the instability of helicopter rotor/body coupling system and the system becomes strongly stabilized in the case of considering flap/lag structure coupling and pitch/lag coupling together.
The finite element method and local stress and strain method were used to obtain the crack initiation life under fatigue load of each pit. After getting the life of crack initiation, the propagation life of initiation crack under pits bottom and the equivalent initial surface crack size were calculated through reverse integration of the Paris fatigue crack growth law and solving the non-linear equation using fracture model. Finally the nonlinear relation was set up between sizes of pits and equivalent initial surface crack by neural network.
A fund distribution model for water pipeline replacement at the level of limited fund is established. By analyzing maintenance fee of pipe network and construction fee, and decreasing the difference of pipeline maintenance fee before and after replacement at the most, the pipeline needed to be replaced is determined. The establishment of model makes construction fund be utilized fully, and decreases pipeline leakage loss most effcfivedy, and provides theoretical support and guidance for water supply department to utilize fund reasonably, control leakage loss and production and marketing difference ratio effectively.
An interactive service- oriented P2P networks architecture (ISPNA) is proposed in this paper. Based on the further analysis on the service demand of distributed P2P applications, and considering the characteristics of P2P networks such as loose-coupled, self-organizing, and scalability, the key availability enhancing issues of P2P networks are resolved by several different layers in ISPNA, of which mutual relations are to analyzed. From the architecture point of view, to synthetically take into account the omnifarious factors that affect the availability of structure P2P networks and to analyze the causes of their formation should be helpful to put the questions in right perspective.
In this paper, the evacuation characteristics of occupants in super- long road tunnels in the case of fires were analyzed and the corresponding safety criteria for evacuations were given. Numerical simulation studies were conducted on the evacuation of occupants under conditions of normal traffics and local jams respectively in a tunnel by taking its structure and the vehicles flows into consideration. Influences of various fire locations, spacing between and widths of transverse passageways were considered. Results show that the available and the required safe evacuation time (ASET and RSET, respectively) are both functions of positions in the longitudinal direction of the tunnel, which is different from the case in building evacuations. Peaks occur on the time curves of occupant evacuations at the gate of each transverse passageway, which is mainly caused by the aggregating and waiting behaviors at each gate. When a local traffic jam occurs, the RSET for the region near the gate of transverse passageways is dramatically enhanced, the same are the hazards. And the performance-based fire protection designs for occupant evacuations in super-long tunnels should consider the influences of fire source locations on occupant loads and the ASET at evacuation gates comprehensively. The investigation for the performance- based fire protection designs for the occupant evacuations in super-long road tunnels could provide the valuable references for the optimization designing of the safety evacuation establishments for the road tunnels.
In allusion to the credit crisis of construction enterprises of China, this paper provides a useful solution that builds the Complex System based Credit Evaluation System of Construction Enterprises (CESCE). Based on the introducing of the characters of Complex System, this paper designs the whole structure of the CESCE by the analysis way of Complex System. The database subsystem, evaluation subsystem and information platform subsystem are showed systematically and the credit evaluation index system, analysis model and data processing method are also presented.
Image segmentation is treated as a key issue in image processing and machine vision, and has been the bottleneck of development. Transition region is a special region located between the object and background. Having the aid of extraction of transition region to segment image is a kind of burgeoning technology. Two kinds of methods have been introduced: methods based on gradient and methods based on non-gradient. Briefly, the extracted effects and existent problem have been analyzed.
This Issue
Sep 2007, Volume 9 Issue 9