Advanced Materials Research Vol. 1014

Abstract: This paper is aimed at the security problems of elevator system.Fuzzy fault tree analytic method is applied to study the reliability of the elevator system.First of all, the elevator system is divided into four subsystems, and then the paper take elevator fall accident as the top event as a example, applying the ascending method for qualitative analysis to find out 7 minimum cut sets in the fault tree and 15 bottom event structure importance sorting. Finally, the fuzzy fault interval probability come out through introducing the concept of fuzzy number in fuzzy set theory, using the triangular fuzzy number to describe the probability of basic event occurrence in the fault tree, making an quantitative interval probability calculation in middle events and top events in the fault tree..The results show that the fuzzy fault tree is an effective and practical method for reliability analysis when we are difficult or unable to obtain the accurate probability of bottom events in terms of the elevator system. Compared with the traditional method of fault tree, the calculated result is more scientific and reasonable, closer to the engineering practice.

Abstract: For costly and dangerous experiments, growing attention has been paid to the study of the performance and reliability of rolling bearings with poor information. The existing reliability theory relying on the classical statistical theory and Bayesian theory will become ineffective if the probability distribution is unknown. In view of this, the developments of studies on forecasting methods for the performance and reliability of rolling bearings with poor information are summarized in this article.

Abstract: Based on information-poor theory, this paper expounds the variable uncertainty, the function polytrope, and the chaotic characteristics of rolling bearing performances, and reveals the nonlinear dynamic characteristics of rolling bearing performances. This can provide a new method of evolvement of characteristics of rolling bearing performances, and offer a train of thought for breaking through the system of the statistical theory which is chronically adopted to evaluate bearing performances, and for opening up a new field of poor information analysis.

Abstract: In the ultraviolet communication system, optical signals being transmitted are not only attenuated in energy, but also affected by the atmospheric turbulence. The effects of atmospheric turbulence intensity and information transmission rate on the BER performance of UV communication system are analyzed and simulated in this paper. It can be found that when the atmospheric turbulence intensity changes from weak to strong, the BER performance deteriorates along, and under the certain atmospheric turbulence intensity, information transmission rate will also have an impact on the system BER performance, the information transmission rate becomes faster, the BER performance gets worse.

Abstract: Takeoff is extremely important to long jump. The paper analyzes the mechanics characteristics of takeoff for long jump by means of the theory of neural network. It firstly discusses some importantly influencing factors for long jump in theory. On the basis of description of the theory of Artificial Neural Network, the back propagation network is applied to model the long jump. The results show that an excellent performance of long jump is depend on a rapid run-up speed and the rhythm of the final two steps.

Abstract: The essay discusses on the flow sensor and the pressure sensor, which collect the signals of PEFR(peak expiratory flow rate) and FEV1(forced expiratory volume in 1 second) of the human body. After the two analog signals go through signal conditioning circuit, ATMEGA128 collects the correspondent digital signals so that realizing fast measuring the PEFR and FEV1, and the result of the diagnosis on the patient’s diseases will directly appear on the LCD, at the same time storing dynamic data as objective index for doctors’ prescriptions and disease analysis. The multiparameter digital asthma diagnosis instrument has a large range of measurement and highly accurate measuring ability, with a small size and high cost, suitable for rural medium- and small-sided hospitals and domestic supervisions.

Abstract: The operation condition for darrieus wind turbine is usually complex in urban sites. One of characteristics is unsteady tip speed ratios during the rotor operating, which makes the widely used aerodynamic performance indicator, maximum power coefficient, not so suitable for evaluating vertical axis rotor performance. In this paper, a new method based on the power coefficient values under variable tip speed ratios was developed and the mathematical expression derived by numerical integration measure was presented. Furthermore, a novel wind turbine power performance indicator, average effective wind energy utilization coefficient, has been defined for the rotor performance assessment. A wind tunnel case of darrieus wind turbine with different blade cord length was selected for analyzing. Results demonstrate the proposed method is correct and practical.

Abstract: Impact of number of tooth matching to load distribution of planetary gears is mainly investigated in this paper. The entire finite element model of planetary gear trains is established so as to analyze and calculate gear stress and number of tooth matching have an impact on load distribution homogeneity of planetary gears on the rated load working conditions. A new method of number of teeth design of planetary gear trains is put forward that number of teeth of sun wheel and number of teeth of gear ring are multiples as great as numbers of planetary gears. Load uneven coefficient of the example is proposed and solved, which provides theoretical basis on carrying capacity calculation, strength analysis and calculation of fatigue life of planetary transmission.

Abstract: Wind turbines consists of three key parts, namely, wind wheels (including blades, hub, etc.), cabin (including gearboxes, motors, controls, etc.) and the tower and Foundation. Wind turbine wheel is the most important part ,which is made up of blades and hubs. Blade has a good aerodynamic shape, which will produce aerodynamic in the airflow rotation, converting wind energy into mechanical energy, and then, driving the generator into electrical energy by gearbox pace. Wind turbine operates in the natural environment, their load wind turbine blades are more complex. Therefore load calculations and strength analysis for wind turbine design is very important. Wind turbine blades are core components of wind turbines, so understanding of their loads and dynamics by which the load on the wind turbine blade design is of great significance.

Abstract: First of all, a new multi-axis wrist force sensor with double bending beams was designed to meet the requirements of the intelligent manipulator. The new structure was easy to process and install. The impact of deformation, error and asymmetry caused by machining and aging treatment was avoided, and the performance of sensor was improved. Secondly, mechanical model of the sensor was established, and the force analyses from different directions were made. Thirdly, after strain gauges were pasted and the bridge was designed, loading tests to single beam and whole sensor were carried out, theoretical calculation and finite element analysis were completed, and the relative error was analyzed. Finally, the causes of relative error in different loading test were studied, and a solution of sensor calibration was put forward.