bluuebunny/crossref_metadata_2025 huggingface dataset:
Real-Time Measurement Method of Doppler Based on GPS Carrier Signals
Authors: Dong Shao Feng , Du Bao Qiang , Zhou Wei
Published: November 2012

According to Doppler effect of satellite on the time synchronization technology between satellite and the ground station, a real-time measurement method of Doppler is proposed based on GPS carrier signals. Using Doppler observations from GPS receiver, the method can real-timely measure Doppler frequency shift of GPS including dynamic Doppler and media Doppler whose error can be timely modified in the receiver end. Simulation results show that the frequency shift caused by dynamic Doppler, a main influencing factor in the course of transmission of time-frequency signal by GPS satellite, is between plus or minus several thousands Hz. Comparing to traditional measurement method of Doppler, the method makes it possible to fast track phase of signal in large dynamic range in synchronous technology.
Compressed Sensing Technology Applied to Fault Diagnosis of Train Rolling Bearing
Authors: Li Xiao Feng , Fan Xing Chao , Jia Li Min
Published: November 2012

Compressed sensing technology is a new approach in the field of signal processing. It can achieve data acquisition and compression at the same time, and express the original signal in a simple way. Network monitoring technology used in detecting the fault of the train’s rolling bearing always produce large amounts of datum. Too much of the parse inspection data cause a lot of unnecessary cost of energy and network bandwidth. In this article we propose a compressed sensing method to deal with the inspection date of train’s rolling bearing which will be transferred in the sensor network to reduce the data quantity. Experimental result show that, after compression and reconstruction, the reconstructed signal still contains most of the information and energy of the original signal, we can still detect the fault of train’s rolling bearing from the reconstructed signal accurately.
Assessment on Pore Structure of Western Sichuan Reservoir through Mercury Intrusion Porosimetry
Authors: Guan Chi , Lou Zhang Hua , Xie Hai Jian
Published: November 2012

Mercury intrusion porosimetry injection is important in assessing microscopic pore structure of reservoirs. This paper introduces an estimated function for investigating the pore characteristic of western Sichuan tight gas reservoir based on VG model. Better correlations between the measured and estimated results have been obtained using VG model. Representative parameters were obtained by ﬁtting the predictions of VG model to the experimental data, and then the estimated formulation was proposed for the studied reservoir. Correlation analysis of the parameters of VG model confirms that absolute permeability and irreducible water saturation are important in mercury injection porosimetry. The approach applied in this paper is helpful in investigating tight reservoirs, especially in the common cases when measurement is difficult to carry out, partly because of complicated variability in the field, and partly because measuring is time-consuming and expensive.
Application of Balanced Multi-Wavelet in the Fault Diagnosis of Rolling Bearing
Authors: Zhang Sui Zheng , Zhang Jian Yu , Yang Yang
Published: November 2012

Multi-wavelet has many excellent properties that single wavelet cannot satisfy simultaneously, such as symmetry, orthogonality, compact support and high vanishing moments etc. It contains several scaling functions and wavelet functions, which can make it match different characteristics of analyzed signal. Therefore, it is always used in bearing fault diagnosis. However, multi-wavelet is multi-dimensional and vibration signal is one-dimensional, so the 1-D vibration signal should be preprocessed before being decomposed with multi-wavelet. It means that the initial data need to be converted to r-dimensional data, and then is input to a tower algorithm. If preprocessing is done, multi-wavelet properties will be destroyed. Due to balanced multi-wavelet has unique properties, the preprocessing can be omitted. In this paper, a balanced multi-wavelet called CL4BAL is designed through balancing original CL4 multi-wavelet and is applied in the vibration signal processing. Comparing the frequency band index after decomposition and reconstruction of CL4BAL and CL4 multi-wavelet, it can be proved that CL4BAL is much better than that of CL4 multi-wavelet in bearing fault diagnosis.
Research the AVG Curve Based on the Method of Flat Bottom Hole
Authors: Wang Xiao Rui , Zhang Xiao Qing , Jia San Shan
Published: November 2012

In order to accurately reduce the equivalent defect error and draw the AVG curve, the relational expression between the sound pressure and the beam path was deduced, which was based on the ultrasonic sound field theory, the complex-variable function and the quadric surface integration. Then this curve was implemented by using the hardware and the software which were based on the above theory. In addition, it was analyzed the factors of attenuation coefficient and fitting the curve--Lagrange interpolation, to reduce the method error. Finally, the analysis of testing data shows that: the AVG curve which is made by flat-bottomed hole can accurately measure the equivalent aperture and reduce the data error, after giving full consideration to the attenuation coefficient factors and curve fitting.
Derrick Stress Monitoring System Based on Fiber Bragg Grating Sensor Technology
Authors: Wang Jun Pu , Wan Fu , Liu Jiong , Sun Hong Xiang , Zhang Hui
Published: November 2012

The importance and urgency for security condition monitoring of the in-service derrick is more and more people paying attention. Based on the FBG sensing technology developed a derrick stress monitoring system. The derrick stress monitoring system, composed by the derrick, a certain number of series of FBG sensors, sensor cables, signal demodulation devices, a portable computer that including a central processing and control platform. Carrying out study in the the ZJ70 model derrick. The experimental results show that the set of strain measurement system has good linear characteristics, repeatability and high sensitivity. Can satisfy the derrick stress monitoring requirement, can realize derrick stress real-time, online, continuous monitoring, expanding the development and application of optical fiber sensing technology in the field of the derrick structure monitoring.
Experiment of Underwater Acoustic Produced by Single Drop Impacts
Authors: Meng Zhao Ran , Zhang Wei Qiang , Sun Hui
Published: November 2012

An experimental study of the underwater sound produced by single drop impacts influenced by different wind speeds, free fall heights and drop sizes at different depths is described in this article. Three kinds of acoustic radiation named impact sound, irregular bubble sound and delay bubble sound are distinguished by the pressure time trace. The images of bubbles taken near the point where the drop falls into water are shown. Some statistics laws of initial impact sound and irregular bubble sound affected by different condition included wind levels, heights of free fall and drop sizes are concluded. The directionality of initial impact sound is measured with wind and no wind. The process of delay bubble entrainment is analyzed and the measurements of bubble excitation probability in different condition are listed.
Distribution of the Stray Current of Rebar in the Ballast Bed
Authors: Dong Zhi Jun , Li Xiao Yi , Yan Pei Yu , Xing Feng
Published: November 2012

Corresponding prevention strategies can be put forward by learning the stray current distribution in the metro rebar. In the paper, the stray current intensity of the rebar in the ballast of the power supply area and the 24-hour polarization potential of the rebar in the ballast are obtained through the test of vertical resistance, track-current drainage net resistance and track-earth resistance, and the polarization potential test in the tunnel ballast of metro system in service. The daily leak of the stray current of the rebar in the ballast is also obtained based on the relationship between the polarization potential and current intensity. The test result shows that the vertical resistance of the track has quite good consistency while the track-current drainage net resistance and track-earth resistance have relatively great discreteness. The polarization potential peak of the rebar in the ballast is over 500mV and the 24-hour equivalent and average current intensity of the rebar in the ballast can rise up to 0.26~0.43A/dm2.
Realization and Comparison of System Identification Based on Different Least Squares Methods
Authors: Zhang Xu Dong , Guan Ji Fu , Gu Liang
Published: November 2012

System identification, which includes parameter identification and non-parameter identification, is to estimate its mathematical model based on the input and output observation in system. This paper discusses the system identification theory and establishes a transfer function of 1/4 vehicle’s second-order vibration system model. Through the discrete transfer function, the system’s difference equation can be obtained to identify the system in two ways, RLS (recursive least squares) and RELS (extended recursive least squares). Finally, the paper makes a comparative analysis about RLS and RELS in connection with the vehicle model. The results show that RELS method is more accurate and has stronger convergence than RLS method, which provides the basis for the researching of control system’s algorithm, simulation and making control strategy.
Nonlinear Iterated Difference Inequalities
Authors: Wang Wu Sheng , Zhao Lian Juan
Published: November 2012

Motivated by Pachpatte difference inequalities and Abdeldaim integral inequalities, this paper establishes two generalized iterated difference inequalities, which consist of multiple iterated sums and contain both linear terms and nonlinear terms inside the sums. We obtain two new results which provide explicit bounds on unknown functions by difference inequality technique. The inequalities given here can be used as tools in the study of boundedness, uniqueness, stability and boundary value problem of a difference equation, which are important tools in studying of natural science, engineering technology, and the laws of social economic development.
The Evolution Model of Emergency Response System for Sudden Accidents of Construction Projects
Authors: Liu Ren Hui , Yu Bo
Published: November 2012

It is a nonlinear complex system for project emergency response system, that is a continuous process for the evolution of emergency construction project development process. The nonlinear differential equations that can describe the sudden emergency construction project the evolution of mathematical models. Emergency system by Logistic model was modified, taking into account the development of emergency systems will certainly be outside the system during the impact, combined with the project incidents of law principles of the role of Heinrich proposed TS-based emergency response system evolution equation Model, demonstrated the system at different stages of the emergency rules and features. For the emergency system in which the different stages of development, the corresponding measures to improve emergency response capabilities.
Reliability Study of Excavation Safety in Underground Space of Chen Clan Academy Square
Authors: Pan Jian , Gao Jue
Published: November 2012

Chen Clan academy square reconstruction project is one of the Asian Game projects. The depth of the foundation pit of the green square is about 12.1m. The difficulties of the excavation are the protection of the ancient buildings of Chen Clan academy and the surrounding buildings and the relatively short construction period. Thus, a top-down construction method was selected as the final method. For security, reliability analyses based on Taylor series technique have been performed to the factor of safety of whole stability, stability against overturning, stability against basal heave and stability against seepage. The results show that the design of the supporting structure is generally reliable, but there are also some potential safety hazards which should be noticed. The application of Taylor series technique also shows the simplification and practicality of this method.
Influence of Radial Slots on the Vibration Characteristics of Circular Saw Blade
Authors: Li Yuan
Published: November 2012

In order to improve thin circular saw blade’s cutting stability, it’s nonlinear dynamic incremental equilibrium equation was obtained according to nonlinear vibration theory and D’Alembert principle. It could be concluded from the above equation that cutting several radial slots on the circumference of the saw blade will cause significant change of dynamic characteristics of the saw blade. This thesis, employing the finite element method and matrix perturbation principle, calculated and studied respectively the effect of number, length and width of the radial slots on natural frequencies of the saw blade. Results show that number and length have distinct influence on natural frequencies but hardly does width have. So proper choice of number, length and width of the radial slots can improve effectively the dynamic characteristics of the saw blade.
Influence of Radius of Horizontal Curve on Driver's Psychology and Physiology on the Two-Lane Mountain Highway
Authors: Zhao Liang , Zhang Meng Li
Published: November 2012

At the present time, the accident remains at a high level all over the world. It mostly happened on the two-lane mountain highway. Through analysis of the relationship between radius of horizontal curve and driving safety of the drivers on two-lane mountain highway, variations of heart rate was be introduced. The variations of heart rate will be changed with Radius of horizontal curve through qualitatively and quantitatively analysis. However, the maximum of drivers' heart rate does not occur on the limit radius of horizontal curve. It locates at the place slightly larger than the limit radius of horizontal curve. The model between heart rate variation and radius of horizontal curve square was established. Finally, some useful advises were suggested to strengthen the two-lane highway management.
Synchronous Transfer Model of Bus Timetabling for Regional Public Transit
Authors: Zhang Jian , Wang Wei , Ran Bin , Li Wen Quan
Published: November 2012

This study is an attempt to optimize the timetable synchronously for regional public transit. Based on the re-interpretation of transfer time in public transportation, a transfer model of bus timetabling is established, which has the objective to minimize the total waiting time of transfer passengers at the transfer station, and it is found as a linear integer model through analysing the established model. Thus, to solve the model, the LINGO software is applied and the corresponding program is designed. Finally, the model is tested against the field data, taking some bus lines in one city as example, using the solution software. The results indicate that the proposed model is reasonable, the timetable is improved, and the solution software program is effective as well.
Analysis of Methods of Creating Microc-Limate for Waterfront Residential Areas in Tropics of South Asia
Authors: Huang Yao Zhi , Jiang Shu Fen
Published: November 2012

To ensure the low-carbon and ecological development of the residential areas, the coordinating climate planning must be done in earlier stage of design, and such design is even more important especially in tropics of South Asia. In order to create a good living environment and improve the quality of life, this paper is intended to create the microclimate in residential areas by guiding the predominant wind direction in residential areas, guiding the wind above water into the space of residential areas and optimizing the arrangement of plants and other aspects through the layout form of buildings under the condition of reducing energy consumption, to reduce radiant heat and meet the comfort of living in the residential areas, thus conducive to the study of design of comprehensive low-carbon residential areas.
An Experimental Investigation of Sunroof Buffeting Characteristics of a Sedan
Authors: He Yin Zhi , Yang Zhi Gang
Published: November 2012

After a short introduction about vehicle wind buffeting noise generation mechanisms, sunroof buffeting characteristics of a production sedan under different wind speeds and operating modes are investigated through full-scale aeroacoustic wind tunnel tests. As sunroof fully open, the severest buffeting effect occurs at wind speed 50kph, with the peak SPL 122dB and the corresponding resonance frequency 18Hz for the test point at the front row. From ca. 60kph it seems that the buffeting effect disappeared. As sunroof tilt, the severest buffeting effect occurs at wind speed equal or less than 30kph, the resonance frequency equal or less than 15Hz. From ca. 40kph the buffeting effect almost disappeared. Whether sunroof fully open or tilt, the resonance frequency increases all along as wind speed goes up till the buffeting effect disappeared (less than 20Hz). Different test positions at the front row or back row show very similar buffeting characteristics.
Application of the Force Transferring Technique for Marine Machineries
Authors: Wang Xue Ren , Miao Xu Hong , Yuan Chun Hui , Qian De Jin , Jia Di
Published: November 2012

It is necessary and valuable to build the transferring relationship between test bed datum and ship datum for satisfying the boundary requirements of exciting forces in ship’s vibration-acoustic analysis. Principle of the force transferring technique for machineries with multiple supporting points is introduced first, and then the measurement method for free velocities of machineries is given. A method for transferring test bed datum to ship datum of machinery force characteristics is discussed and applied to deal with a practical problem, in which the numerical simulation is used for predicting admittance of ship mounting seat absenting reality. Experimental results show that the proposed method is valid.
Modal Identification Based on Hilbert Transform for Time-Varying System
Authors: Zheng Min , Shen Fan
Published: November 2012

Modal identification methods based on the Hilbert Transform are applied to identify modal parameters of time-varying system using impulse response time histories. First, the response data are decomposed into modal responses through the empirical mode decomposition (EMD). Then, the Hilbert transform is applied to each modal response to obtain the instantaneous frequencies. The applications of the proposed methods are illustrated using a 3 degree-of-freedom (DOF) systems with time-varying dynamic characteristics. Numerical simulation results demonstrate that the proposed system identification methods yield good results.
Study on Ambulance Stretcher Vibration Isolation System
Authors: Pan Gong Yu , Zhang Ying
Published: November 2012

The ride comfort is one of the most important performances of the ambulance. In order to avoid patients' illness or injury to deteriorate during the transportation, the ambulance is required to hold smooth motion and high speed. Therefore, it is necessary to develop stretcher vibration isolation system to improve ambulance ride comfort. In this paper, a mathematic model of six degree freedom ambulance-stretcher-occupant system is established. Based on the theory of linear quadratic optimal control, the linear quadratic regulator (LQR) controller of active ambulance stretcher is designed. The simulation results indicate that the active system equipped with the optimal controller has better vibration reduction perfomance on vertical acceleration and pitch angular acceleration of the ambulance stretcher.
Wind-Induced Vibration Analysis of Wind Fence Structure
Authors: Ma Gao Feng , Chen Ting Guo
Published: November 2012

As a new wind-break and dust-control technology, the wind fence is widely used at storage yards in factories and ports. The wind fence structure is a new high-rise wind-resistant structure with light damp and very heavy wind load, and the wind-induced vibration response is unknown and equivalent static wind load is hard to determine in design. Based on the Davenport spectrum, wind-induced vibration of the plane frame structure was analyzed with frequency domain method and the response spectrum of displacement and acceleration were obtained. The equivalent static wind load was studied and the wind-induced vibration coefficient and gust loading factor were gained. The results show that the wind-induced vibration response of the structure is significant, and it should be taken into consideration in structural design.
An Explanation on Mechanism of Local Amplification in Attenuation of Ground Vibration from Rail Traffic in Urban Area
Authors: Liu Hai Ming , Tao Xia Xin , Zheng Xin , Wang Fu Tong
Published: November 2012

The mechanism of local amplifying on attenuation of ground vibration from urban rail traffic is deal with by Zheng et al (2011). The vertical vibrations on ground points of a model with single soil layer overlaid on elastic half-space is calculated with transfer matrix method in frequency domain. The results show that the amplification could be simulated well by the calculation, and the location and degree of the amplification are governed by the ratio between shear modulus of the the overburden layer and the half space , the thickness and damping ratio of soil layers. It is further pointed out in this paper that the most significant factor is the impedance ratio at the buried velocity interface. Then the mechanics is explained as the meeting of the directly arriving surface wave and the reflected and refracted waves from the interface.
Comparative Study on Aerodynamic Noise of Dimensionally Similar Locomotive Models of High Speed Trains
Authors: Wang Yi Gang , Yang Yang , Yang Jia Shun , Yang Zhi Gang
Published: November 2012

This study is focused on the locomotive of high speed train. First, wind tunnel test is used to verify the credibility of numerical results. Then, in order to compare the difference of aerodynamic noise generated by different size locomotive, dimensionally similar models of 1/8th, 1/12th and 1/15th scale are studied by using numerical simulation, including stationary aerodynamic characteristics, fluctuation characteristics of unsteady flow, noise source distribution on surface and far-field noise spectral characteristics. Based on the result of pressure fluctuation, it is noted that the difference between 1/15th and 1/8th scale model is larger in individual parts, including the separation zone in the roof and the edge of window. In addition, according to the far-field noise calculation, the result of 1/12th scale model is better than 1/15th scale model. From the results mentioned above, 1/15th or much smaller scale model should not be used in wind tunnel test as possible.
Dynamics of the Oscillative Solution for a Non-Linear Ecosystem with Impulsive Perturbation
Authors: Tan Yuan Shun , Zhang Hong
Published: November 2012

In the present paper, we investigate an impulsive predator-prey model of integrated pest management(IPM) strategy. Other than the general Holling's functional response, an S-shaped mixed functional response is considered, simultaneously, we model this system assuming that the releasing of nature enemies and spraying of pesticides are impulsive at different fixed moment, which is more realistic comparing with at the same time. With the help of Floquet's theorem, small amplitude perturbation skills and comparison theorem involving multiple Liapunov functions, we show that under some sufficient conditions, the system exists an oscillative pest eradication periodic solution, which is local stable and globally attractive. Otherwise, the system is permanent. This result(threshold) provides us a very useful information for the control of ecosystem.
Research on Numerical Simulation Method for 3D Complex Flow in Rotating Machinery
Authors: Du Guang Yu , Tan Zhen , An Wei , Ba De Сhun
Published: November 2012

A numerical simulation method with gas-structure interaction to analyze 3D complex flow in rotating machinery was presented and the effects with different aerodynamic turbulence model for gas-structure interaction was also presented. The blades are an important component in rotating machinery. Gas flow is unsteady three-dimensional turbulence motion with transient and anisotropic. Then the gas flow and the vibration of rotating blades interfere with each other, resulting in a complex coupling effect. It affects the machine efficiency directly. For discussing the effects on flow field of the coupling field, the blade model was built. And flow around the blades was simulated by gas-structure interaction with three turbulence models respectively. The turbulence models were standard κ-ε, renormalization group κ-ε and Smagorinsky LES. A feasible method was provided for flow field analysis in rotating machinery.
Simulation on Shock Wave Propagation in Metallic Foams Subjected to Impact Loading
Authors: Zhang Yi Fen
Published: November 2012

A discretization elastic-plastic material model was used for simulating the shock waves transmission within metallic foams. The density heterogeneity of metallic foams was considered. Several types of aluminum foams are studied on the transmission of displacement and stresses wave under impact loading. The results reveal the characteristics of compressive wave propagation within the metal foams. Under low impact pulses, considerable energy is dissipated during the progressive collapse of foam cells, and then reduces the crush of the objects. When the pulse is high sufficiently, on the fixed end of foam, stress enhancement may take place, where high peak stresses usually occur. The magnitude of the peak stress depends on the relative density of foams, the pulse loading intensity, the pulse loading duration as well as the density homogeneity of foam materials. This research offers valuable insight into the reliability of the metal foams used as vehicles and protective structure.
Dynamic Testing and Analysis of Inflatable Beams
Authors: Wei Jian Zheng , Tan Hui Feng , Yu Jian Xin , Du Xing Wen
Published: November 2012

Dynamic testing of an inflatable beam has been performed to evaluate structural natural frequencies and modal damping ratios. The inflatable beam has a pattern of six composite fiber strips inside thin-film structure that increases its local stiffness that the structure can be self-supporting in the gravity environment when the internal pressure is released. A measurement setup was installed, and the dynamic testing was performed in this self-supporting state. Dynamic characters of the beams were tested with internal pressure or not when the beam had a 2.0kg mass on the top. Moreover, the dynamic characters before rolled up were contrasted to one after. The experimental results indicate that the self-supporting inflatable beams had better bending stiffness, and the curl folding process had an impact on the dynamic characteristics of the inflatable beam. The pressure affection is not obvious on dynamics of the beam.
Fault Diagnosis of Grinding Machine Using Choi-Williams Distribution Based on COM Module Technology
Authors: Sun Miao Zhong , Wang Chuan , Xu Yuan Li
Published: November 2012

In this paper, a time-frequency analytic system is implemented by using mixed programming of Matlab and Delphi languages based on COM (Component Object Model）module technology. Matlab possesses many signal analytic functions and Delphi has a friendly visual programming environment. These two advantages are fully combined in the mixed programming. This system can be easily upgraded to expand new analytic functions with help of COM module technology. Fault diagnosis of a grinding machine is carried out by using this system. A same vibrational signal sampled from the machine is analyzed in turn by three methods in this system that are Fast Fourier Transform(FFT), Wigner-Ville Distribution(WVD) and Choi-Williams Distribution(CWD). Comparing with the three results, it shows that CWD can get best diagnostic information and validity of the estimation on the instantaneous frequency of a signal. Success of the mixed programming is presented meantime.
Analysis of Orbiting Scroll Overturning for Scroll Compressor
Authors: Zhao Man , Yu Shu Rong , Li Chao , Yu Yang
Published: November 2012

Studies on leakage and friction have received considerable attention in scroll compressor, especially which between the fitting surface of orbiting scroll and fixed scroll, as they affect the scroll compressor performance. According to the scroll compressor working principle and structure, combined with the force model of the orbiting scroll, the overturning moment on the orbiting scroll was analyzed and verified by a specific example, in which the azimuth angle and of the overturning moment action line were calculated and compared. The results show that the overturning moment will have a significant effect not only on the leak and friction loss at the fitting surface of orbiting and fixed scroll, also on the dynamic characteristics of the orbiting scroll due to the linear change of the azimuth angle and the unstable of the azimuth angle . The result is helpful for the study on leakage, friction, and the dynamics and tribology coupling problem research of scroll compressor.
The Frequency Veering Phenomena of the Beams of Cantilever Screen
Authors: Li Ming Ming , Song Fang Zhen , Ding Chuan Guang
Published: November 2012

The special structure of beams of cantilever screen has the advantages comparing with the traditional screen and special dynamic characteristics, such as the dynamic characteristics of frequency veering. The traditional analysis method of vibrating screen is not applicable to its dynamic analysis because of the special structure. By analysis and decomposition of stiffness matrix of beams of cantilever screen, the frequency veering phenomenon of the beam of cantilever screen was explained from the point of view of modal energy equation and the influence of sub-stiffness matrix of beams of cantilever screen on the frequency veering was analyzed. The analysis results showed that the sub-stiffness matrix of the hollow beam and sub-stiffness matrix of cantilever bars is the main reason for the segmentation of modal natural frequencies and the coupling stiffness between hollow beam and cantilever bars is the main reason for the concentration of modal natural frequencies and the formation of the regular mode shapes for cantilever bars group.
Simulation Modeling of Ball Screw Feed Drive System Based on MRAS
Authors: Wang Yong Qiang , Zhang Cheng Rui , Zhang Yue
Published: November 2012

In order to obtain a second-order mathematical model of the ball screw feed drive systems in the designing stage, this paper proposed a simulation modeling method based on model reference adaptive system. In this method, a parallel model reference adaptive system, which regarded the mechanical model as the reference model and regarded a second-order model as the adjustable model, was designed use only input and output measurements based on Popov’s hyperstability theory. And the second-order model’s parameters could be achieved by simulation. The proposed method was confirmed effective through case study. The results show that: the second-order system’s parameters can be identified correctly, and the output of the mathematical model can be followed preferably by the second-order system. The error is less than 0.02mm.
The Dynamic Analysis of High-Speed Cam with Considering Damping
Authors: Su Li Ya
Published: November 2012

With the applied development of Cam mechanism in modern civilization, the running speed of cam mechanisms is increasingly high , the inertial force of system follower raced up.Dynamic analysis and dynamic design must be considered when analyzing high-speed cam mechanism. This article takes combustion engine high-speed Valve cam for example, adopt cyclical motion rule when calculating , follower system would be equaled to Single freedom dynamic model and movement equation would be established. Meanwhile, establishing the movement equation . Use MATLAB to work dynamic response change curve to obtains the different period ratio to push the regulation sector principal oscillation response and ttop the secto sor hangover response far the influence, thus makes the explanation to the period ratio reasonable choice.
Identification of Quadratic Volterra System Using Random Multi-Tone Excitation
Authors: Tan Li Ning , Lu Li Bin , Jin Guo Dong , Li Ping , Liang Juan
Published: November 2012

This paper presents a simplified method for the identification of quadratic Volterra systems. Since the higher order kernels often play a secondary role compared to the linear component of the system, it is worth establishing a balance between the calculation consumption of the higher order kernels and their effect on the model accuracy. The equivalent kernels are used to substitute original quadratic kernels, and therefore both the model complexity and identification computational requirement are significantly reduced. Then the identification algorithm based on least square minimization of model output error and random multi-tone excitation is designed. Simulations show this simplified method is of excellent generalization ability and has robustness against noise in output signals.
The Assessment on the Accuracy of Chart Datum Transfer Algorithm
Authors: Sun Xin Xuan , Xiao Fu Min , Xia Wei , Bian Gang , Jin Shao Hua
Published: November 2012

Chart datum is a vertical reference of ocean depth, which can give the ocean vertical spatial information for Marine Geodesy. Due to time and resource constraints, it is a practical problem of how to determine the chart datum with high accuracy at the short-term tidal stations. In this paper, based on the least-square fitting model, the transfer algorithm for the chart datum at the short-term tidal stations is further developed. Both the accuracy of chart datum computed by this algorithm and the effect on those are presented. The findings of this paper are summarized as follows: The accuracy computed by the least-square fitting model can achieve the centimeter level. The accuracy values determined by the least-square fitting model can further be improved by using the instantaneous ratio of tidal range and selecting the short-distance permanent tidal station.
A Linear Stepping Piezoelectric Motor Using Inertial Impact Driving
Authors: Liu Wei Hua , Wang Yin , Huang Wei Qing , Ding Qing Jun
Published: November 2012

With the rapid development of modern precision manufacturing industry,actuators with high resolution and long stroke are needed in many application fields. Linear piezoelectric motors adopting inertial impact driving mechanism has been driving the interests of many researchers for simple structure and compact size. To increase the efficiency of this type of stepping linear motor, a motor using two piezoelectric stacks was proposed in this work. Two piezoelectric stacks were placed in vertical and were pre-tightened by an elastic thin plate. Support for the stator was designed. Operation principle of this motor was analyzed. To validate this operation principle, a prototype was fabricated and testing on this prototype was conduct too. By applying saw wave voltage signal to piezoelectric stacked in this prototype, the stator of the motor is able to push its mover move with pace length of 2 micrometer.
Analysis on Axial Displacements of an Engine Main Shaft in Complex Temperature Environments
Authors: Pan Jian Zhi , Cao Deng Qing , Chu Shi Ming
Published: November 2012

Considering the characteristics of an aero-engine whose main rotor, as an asymmetric structure, operating in a non-uniform temperature environment, a new dynamical modal of shaft is established for axial displacement analysis based on temperature internal force of non-uniform temperature field. The influence of non-uniform temperature field and the temperature changing are quantified. Based on the influence of temperature internal forces, the analytical formulae of axial displacement of a specified point in the shaft under a continuous temperature field and a discretized temperature field are derived, respectively. At last, the acceleration warming formula is used to simulate the warming up and stable time period, and its variation regularity is compared and analyzed. The relationship between strains of rotor main shaft and temperature internal forces are obtained through the new model and its analytical formulae. Furthermore, the feasibility and relevance of the new model are verified by an equivalent conclusion.
Variable Weight Fuzzy Comprehensive Evaluation Method for Health Condition of Warship Electromechnical Device
Authors: Zhang Guang Yu , Li Qing Min , Ge En Shun
Published: November 2012

Increasing sophistication of naval shipboard machinery coupled with increasing competition for skilled manpower and tightening of defense budgets is forcing the Navy to consider alternative maintenance concepts. This paper proposes a health assessment process in condition-based maintenance architecture based on variable weight fuzzy comprehensive evaluation method. Through analyzing the variables affecting on warship electromechnical equipment condition, a layered assessment index system for warship electromechnical equipment health assessment is built. First, the AHP method is used to determine the constant weight of every index, and then the variable weight model is introduced based on balanced function, in which the constant weight is modified to get the variable weights. By comparing the fuzzy synthetic evaluation based on constant weights with that based on variable weighs, the results show that, the latter is more reasonable and objective, and is also more close to the actual condition of warship electromechnical equipment.
Vibration Characteristics of Single Pile Embedded in Nearly Saturated Soils Half Space Subjected to Harmonic Vertical Loads
Authors: Zhang Hong , Gao Qian , Xu Bin
Published: November 2012

A two-phase wave equation of nearly saturated soils is proposed based on Biot's wave equations and Bardet's assumption regarding nearly saturated soils. Applying Helmholtz vector decomposition and the transmission reflection matrices method, the general solutions to the governing equations for the nearly saturated soils are obtained. Based on the general solutions and the fictitious pile methodology, the Fredholm integral equation for the second kind describing interaction between the pile and nearly saturated soils is established. Solution of the integral equation yields the dynamic response of a pile embedded in nearly saturated soils subjected to a top harmonic vertical loads. Results of this paper are compared with existing results, which shows that our solutions are in a good agreement with existing results. The numerical results of this study demonstrate that the saturation has a significant influence on the dynamic response of a pile in nearly saturated soils.
New Method in Suppressing Vortex-Induced Vibration of Marine Riser
Authors: Zhong Xing Fu , Lin Li Ming , Wu Ying Xiang , Shi Shi Ying
Published: November 2012

Marine risers are key apparatus in connecting the subsea wells to the oil production platform. When the ocean current flow past a riser, the vortex shedding behind riser may induce vibration. If the frequency of vortex shedding is approaching or equal to the natural frequency of riser, the resonance will be generated. Such phenomenon leads to the potential fatigue damage of riser. Therefore, the safety and assurance of marine risers are widely arousing the interest of offshore engineering. In present paper, previous apparatus or methods in suppressing vortex-induced vibration (VIV) of risers used in marine engineering are firstly analyzed, and correspondingly the conditions in design of VIV suppressors are proposed. Based on the Bernoulli equation, the disturbance in flow around a bluff body and the relationship of vortex shedding in span-wise direction, a new method of VIV suppression is proposed. The numerical results have shown that the vibration of risers could be reduced by such disturbance.
Improvements on Technologies of Shield Tunnel Construction in Sandy Soil
Authors: Wang Zhan , Liu Guan Shui , Long Fan , Zheng Fei
Published: November 2012

With development of underground space, the shield tunneling method have been widely adopted due to its unique advantages. However, there is still many technical and theoretical problems need to be improved in the construction. Based on the project of metro line 1 in Hangzhou city, typical problems of shield tunnel construction in sandy soil are analyzed. The problems of ventilation system, cooling water circulation system, foaming system and conveyor belt system are represented in detail. Controlling of proper propelling force is optimized by parameter sensibility analysis. Aiming at these problems, improvement measures are proposed and successfully used in the project. The improvements can be taken for reference in similar projects.
Studies on Aseismatic Performance of a Typical Subway Tunnel with Initial Defects Caused by Construction of New Down-Through Tunnels
Authors: Sun Wei Ze , Dong Jun , Cui Yu Ping , Dong Fei
Published: November 2012

For the engineering background of subway tunnel with initial defects caused by the construction of new down-through tunnels, the aseismatic performance of the existed tunnel is studied so as to reveal the mechanism of seismic dynamic response by using finite difference method. Numerical simulation shows that the tunnel is deforming in its entirety since such physical variables as velocity, displacement and stress in its all key weak points have same dynamic tendency under influence of approaching construction of tunnels, and these variables are much larger than those without any influence. After down-through construction, much influences of aseismatic performance are mainly taking place at both the side wall and the upper arch, and the shearing damage are mainly doing in surrounding soil mass. Due to widely shearing damage after down-through construction, it is suggested that grouting reinforcing should be applied so as to make them much stiffness as a whole.
A Fatigue Analysis Method Research for Main Frame of the Large-Scale Wind Turbine
Authors: Wang Lei , Wu Fa Ming , Lv Xing Mei , Wang Dian
Published: November 2012

This paper presents a method to calculate the main frame damage of fatigue directly by the equivalent fatigue load of the wind turbine. This method can take advantage of the equivalent fatigue load to check the damage of the main frame fast. This paper also analyses the weight of each components of the fatigue load, which is convenient for the optimization design of the structure for main frame. Comparing this method with traditional fatigue calculation method, we can find this method is reasonable and veracious. Using this method can greatly improve the efficiency of the damage estimate for the main frame. It can be analogized to other mechanical components, and this method is very valuable in practical engineering applications.
The Water Adsorption Isotherm Models on Activated Alumina
Authors: Shi Yun Fei , Liu Xiang Jun , Nie Hui Jiao , Liu Yin Shu
Published: November 2012

The adsorption isotherm model of water vapor on activated alumina is an essential equation in designing the performance of adsorption. In this paper, the currently existed 14 isotherm models of water adsorption are summarized. The correlations among these models are analyzed. These isotherm models are evaluated by fitting the water adsorption data on Rhone-Poulenc activated alumina. The results show that AD-Toth, AD-LRC, AD-UNILAN and DMAP can fit the experimental data well.
Research on Reclassification of Power Users for TOU Power Price Based on Fuzzy Clustering
Authors: Luo Ling , Jiang Bao Chen , Liang Li Kai
Published: November 2012

Study on TOU (Time-of-Use) power price in our country almost treats power users as a unified whole, but different categories of users have the different power consumption and way in the actual condition. Therefore, they have different responses to TOU power price. According to the power load features of all kinds of users, the paper presents a solution to reclassify the users using fuzzy clustering algorithm, and provides theoretical basis for implementing categorized TOU power price. Finally comparatively perfect effect is obtained by simulation analysis, and it has great reference value to perfect TOU power price and improve load curve.
Research on Capacitance Current Treatment Methods in Mine High-Voltage Power Grid
Authors: Xu Dan , Guo Na
Published: November 2012

In view of the coal mine neutral point ungrounded system when single-phase ground fault occurs, the grounding capacitance current is too big affect the security of coal mine powe supply.The paper analyzed testing data of capacitance current of coal mine network, established a treating scheme of capacitance current according to evaluating results, namely automatic tracking compensation arc suppression coil devices. The running results show that the scheme limits the size of the ground current and decreases rate of accidents of arc grounding over-voltage, which is good for improving the power supply safety.
The Comprehensive Analysis of Grid Connected Wind Power
Authors: Liu He , Lv Xiang Nan
Published: November 2012

A mixed power grid model of wind power and thermal power was built. The largest output power of wind power and thermal power was gotten by simulation in the condition of ensuring the safety and stability of the grid. Taking largest output power as the boundary condition in economical analysis of the grid, the load dispatch scheme for wind power and thermal power was developed to ensure the optimal economy of the grid.
Modal Parameters Identification of Transmission Tower Based on Improved Stochastic Subspace Identification
Authors: Liu Xiao Feng , Lu Xiu Lian
Published: November 2012

In the condition of environmental excitation and the modal parameters can be identified to only use response data. Based on the improved stochastic subspace identification method, can avoid the fitting error from asynchronous samples, which can integrate asynchronous multi-groups response samples into synchronous pulsing response data, Finally, the identification results of different system order number was utilized to construct stable map to acquire more accurate identification and avoid lost root or duplicate root than the conventional method.
Advanced Metering Infrastructure for Distributed Generation Energy Cooperation Management
Authors: Sui Hui Bin , Sun Ying , Lee Wei Jen , Liu Meng
Published: November 2012

An AMI platform for DG energy management is proposed to provide service both utilities and customers in this paper. By enabling the interactive and efficient communication platform, the proposed AMI facilitates utilities to perform the energy management of DGs, economic dispatch and demand response effectively. Base on the CIM model, OSGi platform leads the AMI extendibility and Interoperability. The communication network includes several advanced communication technology which are used in distributed systems, if the AMI for DG can share the communication network and smart terminal even some advance application software in the utility information platform, it will work more powerfully and effectively.
A Systematic Approach and Genetic Algorithm Method to Power System Stabilizer Design for Wind Turbine Equipped with DFIG
Authors: Sayyad Gholamreza , Khodabakhshian Amin , Hooshmand Rahmatollah
Published: November 2012

This paper develops a power system stabilizer (PSS) design for a wind turbine equipped with doubly fed induction generator (DFIG) which is based on vector control to improve the performance and dynamic stability of DFIG under fault conditions. The proposed PSS design is combined with genetic algorithm to obtain the higher-fitness answer as a strong optimization technique to the design of PSS parameters. A study network containing a wind farm equipped with DFIG was employed and all simulations will be carried out using MATLAB. It is shown that the employment of a proposed PSS can substantially enhance the contribution of a DFIG-based wind farm to network damping and dynamic stability.