Starting from the general developing trend of the world and practice of weaponry construction of armed forces, on the basis of scientific outlook on development, this paper lays stress on questions on qualified scientists and technicians, especialy on the classification, present condition, demand,as well as the strategy of fostering and select of engineering qualified scientists and technicians in the 21st century.
The stresses of dams on river ecosystems are analyzed based on river continuity characteristics. It is pointed but that the advantage and disadvantage of hydropower should be comprehensively evaluated in the compound ecosystem of nature, society and economy. It is feasible to implement ecological compensations for darned rivers by river restoration engineering. It is suggested to conduct value evaluation of river ecosystem services for decision-making of large hydropower projects and establish compensation mechanism.
This paper puts forward “Ideas on Reforming City Gene” and “New Smooth City Mode”. At present, city suffers from fatal gene —“misplaced space”，which leads to ten serious problems hindering city sustainable development： occupation of too much city land, low efficiency, high energy consumption, heavy pollution, great difficulty in parking, poor public security, uncomfortable living environment, frequent occurrence of traffic accidents and huge amount of transportation investment. It is better to carry out study from perspective of 4 levels of “city transportation—city space—economy—society”，locate transportation problems from other point of view instead of from transportation, and get rid of gene of “misplaced space”. Only by this way, can many problems concerning city transportation and sustainable development get solved completely. A disordered city space can be separated into two free spaces by constructing one for cars and one for people respectively, thus constructing a “New Smooth City Mode”. The new mode can realize goal of finding new street system to adapt to characteristics of car transportation as put forward by “Athens Charter” as well as target of building saving and pleasant “human-oriented” city.
The fundamental argument set forth in the paper is that flow is the common feature of fluid flow and substance flow. In view of this, a short review of two ways of describing the motion of fluid in fluid-dynamics was given: one of them was developed by Lagrange, and the other-by Euler. Correspondingly, two methods for substance flow analysis were advanced : one of them is “ following-observing ” method, and the other-“standing-observing” method. The exposition was focused on the former, because it is the new one, on which no information could be found in literature. It is emphasized that the following-observing method is applicable not only for studying steady substance flow (constant output of product), but also for unsteady substance flow (increasing or decreasing output of product). The following-observing model of substance flow was explained by using iron flow diagram in the life cycle of steel products. Introducing the degree of unsteady-state, a set of basic equations for calculating the indexes of substance flow and the relationship between them were derived. The lead flow in Swedish lead-acid battery system was analyzed as a case study, including the calculation of indexes of lead flow.
It will cost much time for numerical simulation of air distribution in train compartment using k - ε turbulence model, so zero equation turbulence model is used for simulating airflow in train compartment. In this paper, zero equation turbulence model and k - ε turbulence model were applied for numerical simulation of indoor fluid flow and heat transfer respectively. By comparison, the results come from these two. methods are inosculated very well, and the time cost by zero equation turbulence model is very little. So zero equation turbulence model has the merit of simpleness and quickness, it will provide a simple and convenient numerical simulation method for the design of train air-conditioning system.
It had been believed that the genesis of Gejiu tin deposits were granitic mineralization of Yanshanian epoch by most researchers for a long time. However, recently the authors obtain a great deal of information to indicate that the Gejiu tin deposits are occured as mineralization of many time periods and many sources, being divided as three metallogenic series namely the seabed basic volcano- metallogenic series, the seabed exhalative hydrothermal metallogenic series in the Indo-Chinese epoch and the granitic superimposed metallogenic series in the Yanshanian epoch. The metallogenic pattern may be summed up as “rift setting—the volcano-sedimentary metallogenises—the exhalative hydrothermal sedimentary metallogenises—the granit rebuild superimposed metallogenises”.The paper demonstrater the metallogenic viewpoint in terms of the trace rare earth element, stable isotopes and fluid inclusion.
In this paper, a new kind of damage evolution equation is presented by the method of phenomenological analysis and microscopic statistics. And on the basis of this several spallation criterions are established, which are used easily in engineering. By the numerical simulations of the free surface velocity histories and based on the best consistence between the computational results and the experimental ones, the material parameters in the damage evolution equation and the spallation criterion are obtained. The satisfactory agreement between the computational results and the experimental ones show that the new form of damage evolution equation and the spallation criterion are reasonable, and the method of determining the material parameters is effective.
At present, many detecting methods for harmonic and reactive currents have been put forward. Though having their characteristics respectively, they have insurmountable problems, such as vast calculating work, bad real time performance, low measurement precision and so on. Based on the foundation of load current analysis, a new real-time detecting method for harmonic current based on iterative algorithm in active power filter is proposed, It has the characteristics of very little calculating work, nice real time performance and high measurement precision. The correctness of the method is verified by theory analysis and computer simulation research.
Subjected to the annual changes of the air temperature, the quasi-period rules of the operational parameters of the buried hot oil pipelines and the surrounding soil temperature are theoretically presented in this paper. On the basis of large numbers of actual operational data, the rationality of the rules is further validated. In addition, the delay of the operational parameters must be considered in the studies of the saving energy, optimizing operation and economically pigging for hot oil pipelines.
Because it takes too much of time in fractal image coding, the paper analyses the factors that affect the speed of fractal image coding , and proposes a novel idea by using the reformed variance (tentatively) to improve image fractal compression performance . A theorem is proved that the IFS cannot change the image blocks' reformed variance. Moreover , it gives a novel fractal image compression method based on the reformed variance. The simulation results illuminate that the new method can run fast, at the same time it can improve the PSNR when compared with other fast algorithms.
The purpose of this paper is to discuss the infection of supply chain management in the IT age , especially the functional disadvantage of supply chain management software named SCM. On the basis of intellective mathematics, the paper puts forward some concrete development countermeasures for modern logistics business, depending on the methods of intellective mathematics model. And an example is offered with the SWOT method.
With the development of bridge construction, none of the traditional approaches, i. e. bar chart and network diagrams, etc. , has the capabilities to match the development of construction management. Combined the object-oriented system simulation technology for complex engineering system with the CAD digital modeling technology, the system simulation of bridge construction based upon 4D CAD was presented, which linked a 3D model of a construction project with a project activity schedule element. The dynamic visualization of construction process and intuitive analysis on the optimization of construction schemes were achieved. And the corresponding software of visualization simulating system, based on 4D CAD, for construction of bridges was programmed with visual C++. The successful application of the software to the practical cable-stayed bridge showed the practicality and preponderance of this method.
Adaptive modulation techniques can improve the BER (bit error rate) performance or the average throughput by employing a suitable modulation mode depending on the instantaneous channel SNR (signal-to-noise ridio). In this paper the optimum SNR thresholds over a 6-path Rayleigh channel are derived, which shows a superior BPS (bit per symbol) throughput performance while maintaining the target average BER. The 6-path Rayleigh channel is often applied to mobile environment with high-speed. The results achieved in this paper can be applied to the adaptive modulation system with the channel of ITU-R M. 1225 Vehicular Test A mode.
The water aerosol fire-extinguishing agent (WAE) is a new generation of Halon replacement. When the fire is taking .place, WAE will rapidly burn and generate a great deal of inert gas, hot mist and a little amount of particulates. After those combustion product are cooled in the cooling layer, they will be discharged into the ambience and extinguish the fire. So, to WAE, the combustion rate has an important effect on the fire extinguishing efficiency. This article mainly discusses the influence law of WAE's compositions on combustion rate.
In order to choose the most economical and efficient airliner environmental control system, several types of air cooling systems for the modern airliners were optimized and compared. The optimized mathematical models of two wheels system with low pressure water separation, three wheels system with high pressure water separation and four wheels system with high pressure water separation were established respectively. The fuel oil loss for airliner environmental control system is taken as the objective function. Generalized multiplier combined with simplex method is used to seek the optimum solution. The optimized results can be used as the theoretic foundation for the design and research of airliner environment control system.
The semiconductor gas sensors sensitive to hydrogen and carbon monoxide are chosen to compose the gas sensor array, and an on-line data acquisition system is constructed, which is combined with the pattern recognition techniques of self organizing competitive network for the research of gas qualitative analysis. In order to eliminate the effect produced by the gas concentration, three kinds of normalization methods are developed to pre-process the sensors responses toward hydrogen and carbon monoxide. The research results show that the accurate identification of hydrogen and carbon monoxide in the finite range could be accomplished by relative method.
Mobile robots motion planning is one of the key technologies in the robot navigation. During the past 40 years of mobile robot development, lots of planning algorithms were proposed. Because of the tremendous difference among environment models and planning methods, it is difficult to compare them experimentally. This survey reviewed the classical planning algorithms in the history of robot development and presented a set of criteria of planners and the formal description of the problem of planning. The paper described each algorithm's principle or main technology in detail and classified the algorithms based on environment model and search strategy. They are classified into four categories, that is, planners based on geometry construction of free spaces, forward graph search algorithms, random sampling-based motion planning algorithms and intelligent planners. Last, The paper compared and summarized their performance and gave an outlook to the future research of the mobile robots motion planning.