Applied Mechanics and Materials Vols. 190-191

Abstract: This chapter reviews the objectives and techniques used in the control of wind turbines at the individual turbine level, where controls are applied to the turbine blade pitch and generator. The paper analyses the control strategy of the wind power generation, optimizes the power output energy conversion factor of the optimal tip-speed ratio and the optimal tip-speed ratio using the clonal selection on quantum genetic algorithm. After reviewing basic turbine control objectives, we provide an overview of the common basic linear control approaches and then describe more advanced control architectures and why they may provide significant advantages.

Abstract: In computer vision field, video target tracking has important significance of research. This article proposed a fast and efficient multi-cameras-relay target tracking method directed at crucial technology questions in video target tracking. First, it separated the foreground and background of monitoring scene using of Markov random field theory, and then established the Markov random field model of foreground and background, so as to accomplish the moving object recognition; The next, it located the accurate positioning and tracking utilizing the combination of Kalman filtering and improved Camshift algorithm; finally, it made more-cameras-relay target tracking on the basis of coordination and synchronous between cameras, to achieve high efficiency of tracking and strong robustness and monitoring of the wide range of target real-time tracking.

Abstract: The application of vacuum preloading for soft foundation treatment in grain storage is introduced from its principle，design，construction and the inspections. Its obvious effect is proved by example. The east coast of China is the most developed economical area and major grain and oil manufacturers. Many grain and oil depots have been established. However, in the places where the depots located, soil is soft dirt with low strength grade, high compressibility, small permeability and high possibility of plastic flow, has increased difficulties of grain and oil depots foundation construction. Without enough knowledge of soft soil and lacking of proper foundation construction method and good technology, depots may slip due to foundation’s erosion, and big settlement. If the structure slips, equipments for aeration, dehumidifier, antivirus equipment cannot work well. Based on the statement above, reasonable and effective methods for soft soil foundation work is the key point for construction of high quality and high standard grain and oil depots. This paper mainly discussed when we do depots construction work on the soft soil foundation, exact calculation, construction method and result test of fasten method for the soft foundation under the vacuum circumstance of preloading.

Abstract: The railway canopy and mechanical canopy in the granary are large span special structure industrial architecture, has the design standard uncertainty, influence factor multiplicity, construction craft complexity questions and so on in the design and the construction. On the basis of obtaining the characteristics of granary railroad canopy, the design methods of roof, column and foundation for granary railway canopy are described, the defects of stability theory are analyzed, and the reasons of instability is summarized in this paper. The results will has good reference to similar projects in the future.

Abstract: From an engineering reality, in order to solve complex stratigraphic drilling problems and improve construction efficiency, the method of combination of large diameter DTH hammer and the pile driver with a special long spiral drill multifunctional is proposed. This method has the characteristics of simple equipment, fast, effective, low cost etc. It can quickly drill through layers of gravel, stone, weathered bedrock, reach to depth up to above 25m. It has been widely used in embedded engineering methods of precast piles, the long spiral rock-socketed piles, piles into the rock currently. The study of this construction method has not only wide range of applications, but also has a wide range of practical and theoretical significance.

Abstract: This article selected a typical loess slope engineering as the research object, and through the characteristics of loess landslide, landslide environmental geological conditions, the formation mechanism of the landslide study of the loess area of urban slope instability factors, loess slope stability of the calculation method and reinforcement measures, the loess slope stability study area has a large reference.

Abstract: It is evident that a pulsatile flow is important for blood circulation because the flow pulsatility can reduce the resistance of peripheral vessels. It is difficult, however, to produce a pulsatile flow with an impeller pump, since blood damage will occur when a pulsatile flow is produced. Further investigation has revealed that the main factor for blood damage is turbulence shear, which tears the membranes of red blood cells, resulting in free release of haemoglobin into the plasma, and consequently lead to haemolysis. Therefore, the question for producing a pulsatile flow with low haemolysis becomes how to develop a pulsatile impeller pump with less turbulence The authors have successively developed a pulsatile axial pump and a pulsatile centrifugal pump. In the pulsatile axial pump, the impeller reciprocates axially and rotates simultaneously. The reciprocation is driven by a pneumatic device and the rotation by a DC motor. For a pressure of 40mm Hg pulsatility, about 50mm axially reciprocation amplitude of the impeller is desirable. In order to reduce the axial amplitude, the pump inlet and the impeller both have cone-shaped heads, thus the gap between the impeller and the inlet pipe changes by only 2mm, that is, the impeller reciprocates up to 2mm, a pressure pulsatility of 40mmHg can be produced. As the impeller rotates with a constant speed, low turbulence in the pump can be expected. In the centrifugal pulsatile pump, the impeller changes its rotating speed periodically; the turbulence is reduced by designing an impeller with twisted vanes which enable the blood flow to change its direction rather than its magnitude during the periodic change of the rotating speed. In this way, a pulsatile flow is produced and the turbulence is minimized. Compared to the axial pulsatile pump, the centrifugal pulsatile pump needs only one driver and thus has more application possibilities. The centrifugal pulsatile pump has been used in animal experiments. The pump assisted the circulation of calves for several months without harm to the blood elements and the organ functions of the experimental animal. The experiments demonstrated that the pulsatile impeller is the most efficient pump for assisting heart recovery, because it can produce a pulsatile flow like a diaphragm pump and has no back flow as what occurs in a non-pulsatile rotary pump; the former reduces the circulatory resistance and the later increases the diastole pressure in aorta, and thus increase the perfusion of coronary arteries of the natural heart.

Abstract: From 1960 to 1999, the river regime in the Lower Yellow River had been the wandering. After the operation of Xiaolangdi Reservoir, the river regime in the Lower Yellow River has experienced some changes because of the reduced discharge and sediment loads. According to the river regime maps, the wandering features of the Lower Yellow River are inhibited and the river channel is becoming stable. In addition, the fractal dimension method is introduced to discriminate the river regime. The river fractal features are able to reflect the features of river system and the fractal dimension is an important variable that can reflect the fractal features. Based on the basic principle of fractal theory, the fractal dimension method is applied to discriminate the river pattern evolution of the Lower Yellow River. The results show that all the fractal dimensions of the three studied reaches decrease from 1-1.35 before 2004 to less 1.05 after 2004, indicating that the river regimes are becoming more regular. It means that the discrimination results fit well with the facts and the fractal dimension method is suitable for the river pattern discrimination.

Abstract: The cooling process of heavy rail is the important step to the output, that the preflexed rail is cooled on the stepping-type cold bed which has been carried by the chain transmission device. We employed the finite element method to analyze the bending deformation of the U75V rail through natural cooling process, the effected factors including the rail side-laying on the cold bed, the latent heat of phase change, and the thermal radiation are considered in the analysis. In the paper, we discussed the establishment of the heavy rail cooling model, the cooling parameters and the boundary condition, and emphatically analyzed the rail bending deformation changes and its principles through the cooling process. The study of the hundred-meter high speed heavy rail can provide the theoretical foundation and reference value to the formulation of cooling technical parameters and preflex technical schedule.

Abstract: Evaluation indexes (monitoring value) set in safety evaluation of dike, it was difficult in conforming the range of evaluation indexes, and could not reflect characteristic of outburst destroy. Catastrophe theory is a kind of mathematical method that problems of transition, discontinuity, and abrupt qualitative change based on analysissitus, problems about how a system of continuous quantitative change to evolving into jumping qualitative change can be analyzed. Firstly, the relation between deformation of dike with components of water pressure, temperature and time effect is analyzed, subdivision lemma of cusp catastrophe theory is cheesed, expression of potential formula on horizontal deformation is carried out based on influence of factor of time, water pressure and temperature. Moreover, normal form of catastrophe is advanced and critical rules of dike safety are put forward, evaluation model based on catastrophe theory is established. Finally, the model is validated with dike of Yellow River. Analysis shows that evaluating conclusion of the model is as the same as the practice, and it can not only reflect outburst destroy character of dike, but also evaluate safety degree in quantity, thus the model is good in adaptability and precision.