Advanced Materials Research Vols. 490-495

Abstract: Metadata management algorithm plays an important role in file system performance and file system is the most common way of data accessing in mass storage systems, so metadata management algorithm is very important for the performance of mass storage system. In this paper we analyze current metadata management algorithms and bring in the metadata dynamic hashing algorithm to solve the problem of poor adaptability of them. We realize the prototype on Lustre. After testing system performance with common tools by adjusting the several parameters’ value of metadata dynamic hashing algorithm, we find that performance of the prototype I/O is superior to Lustre. Furthermore, we analyze impacts of the parameters of dynamic hashing function on I/O performance of prototype

Abstract: This paper studies the H∞ control problem of networked control systems (NCSs) with random time delay and packet dropout, respectively, for the case that system state is unavailable. The output feedback closed-loop NCS is modeled as a discrete-time switched system. A necessary and sufficient condition is derived for the NCSs ' asymptotic stability based on robust stability techniques, under which the system is exponential stability with a desired H-infinity disturbance attenuation level. The designed output feedback based H∞ controller is obtained by solving a set of linear matrix inequalities. The result illustrate that the effectiveness of the proposed control design and the satisfactory performance of the system.

Abstract: This article through to the modern small-bore of empty weapons destroyed fighters of the mechanism of target analysis, according to improve small arms fire destroyed target empty the effective method of probability, based on the high value MEMS sensor and passive g static detection technology, this paper expounds the MEMS sensor and electrostatic detection technology in a new small weapons development to meet the demand of the empty the application of composite fuze. At the same time, to a certain extent, describes this composite fuze work mechanism and method, the composite fuze success can effectively enhance the development of weapons of small empty combat performance.

Abstract: Established a single-disc rubbing rotor system test-bench ,and can simulate the design of a single point of rubbing and rubbing of the rotor part. In the case of constant speed to ensure that observed in the rubbing rotor vibration under different conditions, the use of waveform, frequency spectrum, Orbit and other detailed analysis of the system before and after rubbing and chaotic properties of nonlinear response the experimental. results show that the occurrence rub rotor system, the system will stimulate a high frequency and fractional-octave, when there will be a serious rub chaos.

Abstract: Voltage-Displacement Performance (VDP) is one of the most important characteristics of cymbal when it is used as actor. Based on analyzing the piezoelectric ceramic sheet stress of cymbal transducer, the piezoelectric equations with boundary stress conditions are given. And a VDP function of cymbal transducers is established. It is validated that the calculation results by the VDP function agree with the results by experiments. Through analyzing the VDP function, some curves of the relationship between the parameters of cymbal transducer and equivalent piezoelectric constant de33 are given. These curves are useful to cymbal transducer errors controlling, batch producing, and consistency performance controlling.

Abstract: To avoid the difficulty of collecting accurate traffic flow data, this paper proposes a novel approach for congestion features extraction from traffic video. The approach firstly segments the traffic video into shots and the shot motion content feature is extracted. Then, we extract the key frames applying an improved global k-means clustering algorithm. The last congestion feature of the global optical flow energy is computed based on the key frames. The numerical experiments on traffic surveillance video show the validity and high accuracy for traffic congestion detection using the propose method in this paper

Abstract: Aiming at the intelligent integrated detection System for test and measurement of many different missiles, utilizing the data acquisition technology, virtual instrument technology and signal analysis technology synthetically, in this paper, we introduced the system architecture and accomplished the hardware design and software implementation. Practical applications of the prototype system have proven that this intelligent integrated detection system has more powerful functions, better interaction and more convenient operation than the traditional automatic test system(ATS), it have met the needs of test and measurement of several different missiles

Abstract: For the problem of MFL (magnetic flux leakage) inner detection signal reconstruction for pipeline, a method based on the FR conjugate gradient iterative was introduced to solve the inverse problem of electromagnetic field. The physical model of magnetic flux leakage inner detection in pipeline had been established by the finite element analysis software named ANSYS. 90 groups of different parameters of defects had been simulated in MFL. Fundamental function had been found by fitting curve. FR conjugate gradient iterative had been programmed by MATLAB in order to solve nonlinear equations. Comparing with Newton, conjugate gradient can get reconstruction defect parameter more accurately and better reconstruction results.

Abstract: Aimed at the diagnosis to compound faults of eccentricity and teeth broken in gear box, the paper presents a method of compound fault diagnosis based on the blind source separation to separate the coupling characteristics in compound faults. The method separates two collected signals including some compound faults into two independent source signals, and then extracts the signal characteristics, i.e. the fault characteristics of gear eccentricity and teeth broken, through resonance demodulation. The result of the experiment shows the validity and practicality of the method.

Abstract: This paper introduces a computational model for calculating the lifetime of rolling bearings in a 1.5MW wind turbine’s epicyclic gearbox. At first, a quasi-dynamic model is established to analyze the skidding of bearings and the skew of rollers. Then, the load distributions on raceways and inner rings of bearings are calculated using the quasi-dynamic model. Meanwhile, a multi-body finite element model established in RomaxWind software is utilized to simulate and analyze dynamics behaviors of the epicyclic gearbox including all bearings. The comparison of bearings’ lifetimes calculated with different methods shows that the quasi-dynamic model can obtain very close results as the multi-body finite element model obtains, but costs less time. Failures occurring on inner and outer rings, such as pitting, adhesion, are mainly resulted from the misalignment of inner rings and roller number on the skidding of bearings