Multidisciplinary design optimization (MDO) is regarded as the most hopeful upgrade of current methodology for complex system design. In order to overcome the difficulties in advanced aero-engine design, such as complex coupling relations and serious conflicts between different disciplines, the research, development and application of key technologies of MDO have been carried out in three phases: part design, component design and whole engine preliminary design. And a MDO-based integrative aero-engine design method is presented. Five examples of engineering applications are given to demonstrate that the proposed method can improve aero-engine design ability very much comparing with the traditional method, and is prospective to be applied widely to engineering field.
As an important natural resource, tidal flat imposed wetland is expected to be kept harmonious balance between utilization and protection. Based on the case of Shanghai area in the Changjiang Estuary, concept of tidal flat is firstly discussed on its spatial range in this paper. Fundamental features of tidal flat, and its responsibility to the discharge change of water and sediment transported by the Changjiang River, intensity of exploitation and demands of wetland protection are discussed. Present dynamic processes and change tendency of different types of tidal flat are illuminated in detail. Some new-points are proposed for the reasonable exploitation, dynamic protection and ecosystem resilience of each individual tidal flat and imposed wetland. Some suggestions are also proposed to make a further study about the sustainable spatial resource exploitation of offshore in Shanghai area.
This article introduces three outstanding innovations: Utilization of steel casing to establish a construction platform for Sutong Bridge' s super-large and deep-pile groups ; Permanent collision facilities consisting of collision structure and 5 000 ton steel cofferdam which is lowered as a whole; Permanent scour protection. The article also presents economical and reasonable design method for super large bridge foundation and explains the significance of innovation and technical integration to large and complicated project construction based on the above theory.
The paper presents the realization, at NIM, of SI time unit second using the NIM4 cesium fountain clock, SI length unit meter using a femto-second (FS) optical frequency comb and calibration of wavelengths of stabilized lasers by this FS comb. The uncertainty of NIM4 fountain clock was evaluated as 5 × 10 - 15. The frequency uncertainty of the FS optical comb locked to a H-maser, which is steered by NIM4 clock, was estimated as 2. 2 × 10 - 14. The function, significance of Cs fountain clock, stabilized lasers, optical comb and relationship among them are discussed. Finally the progress of NIM5 fountain clock and the construction of a Sr atom optical clock started in 2006 at NIM are reported.
The SARS in 2003 is a public health crisis in China. The passenger transport witnesses serious landslide and suffers a heavy loss. In this article, the loss of passenger transport and its regional difference impacted by SARS are analyzed and estimated. The loss of passenger transport is nearly 1. 007 billion person- times in 2003 impacted by SARS crisis, in which the highway transportation loss is 888 million, the railway loss is 105 million, the aviation is 16. 12 million and water carriage is 19. 43 million. As a short breaking event, it starts from March in 2003 for the crisis formation, breaks out in whole from May to June, and enters the decay and comeback from July to August, and has a compensating from November to December after the crisis. Due to the difference in transport location and epidemic situation, the loss of passenger transport impacted by SARS in 28 provinces in China can be classified into 4 types. Guangdong, Sichuan and Hebei suffer the most and the loss is over 100 million person-times. The relativity analysis is carried out based on the loss of transportation, cardinal number in 2003 and the number of infect person of SARS, and a new spatial forecast model is put forward for space forecast in transport crisis. The model shows that the marginal coefficient of transportation cardinal number is 0. 788 46, the marginal coefficient of SARS patients is 0. 075 868.
This paper has analyzed deficiencies with the current aircrew escape system for sub-plateau regions and a proposal has been put forward that the ejection seat is to be equipped with a dual mode sequencer including mechanical and electrical sequencers, so as to ensure safe escape, under the condition that the current equipment configuration is kept unchanged, in sub-plateau regions and without reducing escape performance at low altitude under adverse attitude conditions in plain regions.
A novel cellular automata (CA) — two-dimensional controllable CA — is proposed in this paper. According to characteristics of two-dimensional controllable CA, a pseudo random generating method based on two-dimensional controllable CA with a trapezoidal structure is presented. Simulation demonstrates that pseudo random bit sequence generator based on the two-dimensional controllable CA with a trapezoidal structure is easily implemented, and can generate high speed bit sequence and excellent statistical properties. This novel CA is widely used in symmetrical cryptography.
The methodology of visual simulation for tunnel engineering construction schedule is presented in this thesis. Visualization of founding model, calculation and result of construction schedule simulation are realized. The simulate model of tunnel engineering construction schedule is founded. Risk analysis and decision_making method of tunnel engineering construction schedule based on visual simulation are presented. The resource optimization is conducted. On the basis of studying the S curve theory and method of schedule management, tunnel engineering construction schedule S curve real time management and control method based on visual simulation are presented. Practical engineering analysis is made.
The traditional method for obtaining aerodynamics coefficient for ejection seat is wind tunnel experiment. To research the feasibility of the application of computational aerodynamics coefficient for ejection seat on general CFD software, aerodynamics coefficient of ejection seat was computed using general CFD software. Through resolving fluid field, the result is obtained. The average difference of the result compared with the experiment data is less than 10 % and in the range of permission. It shows that CFD methodologies can be used instead of wind tunnel experiment for the ejection seat research. CFD methodologies can be applied widely to ejection seat research.
Experimental tests on 10 mm cubic concrete specimens were carried out using the servo hydraulic testing machine. Specimens subjected to equal constant confining pressures of 0, 4 MPa, 8 MPa, 12 MPa and 16 MPa respectively were conducted to investigate the deformation and strength characteristics of concrete. In addition, strength properties of concrete under unequal confining pressures were also investigated. Based on the test results it was revealed that the ultimate strength increases dramatically with the increasing confining pressure and the strain at peak stress increases even more pronounced. With the increasing minor principal stresses, the enhancement effect of middle principal stresses on the ultimate strength became weak. The complete stress- strain curves were obtained at different confining pressures. By comparison with the current literature, appropriate formulas of concrete strength and deformation were proposed for the engineering purpose.
In this paper, at first research of relation between correlation-interval and estimation accuracy is carried out, and the optimal correlation-interval is proved to be existent that is adaptive to signal-to-noise ratio and velocity varieties. Then some special characteristics of the optimal correlation-interval are explored. Based on them an iterative correlation-interval optimized (CIO) algorithm is proposed. It optimizes the correlation- interval and calculates the Doppler spread by increasing the resolution on time-domain iteratively. Simulation results show that contrasted to conventional schemes the proposed approach is less sensitive to signal-to-noise ratio and velocity varieties, and can improves the performance dramatically in low signal-to-noise ratio environment in which the conventional schemes has a poor performance. It achieves the high accurate estimation of Doppler spread directly.
The paper studied the radio resource fairness scheduling for Orthogonal Frequency Division Multiplexing Multiple Access (OFDMA) systems which was supporting several different services. After deeply analyzing a classical resource scheduling algorithm, which maximize the worst user's capacity, an improved algorithm which can evidently enhance the fairness performance was proposed. Simulation results show that the improved algorithm can keep a better fairness performance under different application environment, and can more strictly guarantee the required data rate for different service.
Based on the solar cell DC model and the mathematic expression of maximum power point, the equations describing short circuit current, open circuit voltage, maximum power current, voltage and filling factor varying along with the illumination intensity are deduced and calculated with two real solar cells data. The fact that short circuit current and maximum power current are proportional to the illumination intensity, and open circuit voltage and maximum power voltage are proportional to the natural logarithm of illumination intensity is certified. The relation of filling factor varying along with the illumination intensity is not a simple functional expression and effected by the solar cell model parameters is present. A simulated experiment is established to valid the theoretic analysis and calculating by Multisim.
As the development of cities becomes more quick, the accidents happened in public venues resulted form massing crowd become more and more. This paper uses social risk to quantify the risk. On one hand, in terms of former research outcome, the paper deems that the occurrences of the accidents in public venues, in a time span, can be described as Poisson distribution, and then, the quantitative model of accident occurrence probabilities can be reasonal out. On the other hand, through the sum of the occurrences of accidents of different severity level, which is to embody the situational probability of accidents of different severity level with its frequencies, the outcome of accidents mortalities will be obtained, which is used to figure out the probabilities of the accidents of different casualty numbers. In the end, the F - N curve will be achieved. To use the F - N curve, it is able to analyse the social risk of crowd massing venues. Taking some statistical accidents as references, it describes how to use the model. The result proves the model is reasonable and accurate to a certain extent.
Exponential smoothing is an efficient method for forecasting and decision-making. The forecasting model of exponential smoothing to forecast the displacement at Observation Point 5 of certain city hazardous landslide is applied in this paper. According to the characteristics of observation forecast formula with linear trend of the twice exponential smoothing, appropriate formulae calculating at, bt and suitable exponential smoothing value are selected and used to make a forecast. The forecast results show that the errors between the forecast values and the observation values are very little. And it shows that this model may be well applied to the forecast of the displacement in the deformation of slopes.
It's very important to heighten the management level of enterprises in order to enhance the competence ability. This paper sets forth the importance of infomationization for enterprise management, and points out the developing direction of modern commercial banking corporations in terms of digitized information management.