bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical computation for the impact of flow rate and rotational speed on the flow-induced noise of the centrifugal pump
Authors: Wang Yue , Song Bi Feng , Song Wen Ping , Ren Juan
Published: December 2017

This paper adopted an indirect mixed method (computational fluid dynamics + boundary element method) based on computational fluid dynamics + Lighthill acoustic analogy theories to compute the flow field and flow-induced noise of the centrifugal pump, and experimentally verified the correctness of computational results. The pressure distribution of the centrifugal pump through an unsteady computation showed that there were obvious separation vortexes at the outlet of the centrifugal pump and pressure at the edge of impellers was obviously more than that of other parts. There were many peak noises on the sound pressure level curve at the outlet of the centrifugal pump. The sound pressure level gradually decreased with the increased frequency. However, sound pressure levels will be a stable value when the analyzed frequency was more than 3000 Hz. Sound pressures at the inlet and outlet of the centrifugal pump were relatively large. Sound pressures at the inlet pipeline gradually decreased from outside to inside and sound pressures of outlet pipeline gradually decreased from inside to outside. The structure of the centrifugal pump was not completely symmetrical, and the sound field was not symmetrical. In addition, the radiation noises in the external field at the inlet and outlet of the centrifugal pump were similar to the radiation of many point sound sources. Peak values of flow-induced noises at the outlet of the centrifugal pump were more than those at the inlet of the centrifugal pump under the working condition of different rotational speeds and flow rates. In the meanwhile, sound pressure levels at the inlet and outlet of the centrifugal pump did not show many differences in amplitudes when the rotational speed was small. When the rotational speed reached up to 3000 r/min, the sound pressure at inlet was more than that at outlet within 1500 Hz-4500 Hz. At many peak frequency points, peak noises at outlet were obviously more than those at inlet, which thus proved that fluid caused large pressure fluctuations due to the interaction between impellers and volutes after flowing through the centrifugal pump and flow-induced noises caused by pressure fluctuations were mainly reflected in blade frequency. The change of the rotational speed and flow rate would not only increase the flow-induced noise in the centrifugal pump, but also seriously affect the external radiation sound field of the centrifugal pump.
Propagation of rotational waves in a block geomedium
Authors: Erofeev Vladimir I. , Leontyeva Anna V. , Pavlov Igor S.
Published: December 2017

On the base of assumption that the rotational movements of the chain of the crust blocks and the corresponding rotational waves characterizing the redistribution of tectonic stresses are described by the sine-Gordon equation with dissipation, the dispersion properties of this equation are analyzed. It is shown that the dispersion is manifested in the low-frequency range at high values of the dissipation factor. The presence of anomalous dispersion has been revealed for all values of the dissipation factor. Influence of this factor on dispersion is investigated. Some features of propagation of a stationary shock wave in a geomedium are studied. It has been found that the shock wave front width is directly proportional to the nonlinear wave velocity and to the dissipation factor of the medium, but it is inversely proportional to the nonlinearity coefficient.
Fault diagnosis of rotor using EMD thresholding-based de-noising combined with probabilistic neural network
Authors: Liu Dong , Zeng Hongtao , Xiao Zhihuai , Peng Lihong , Malik O. P.
Published: December 2017

De-noising of signal processing is crucial for fault diagnosis in order to successfully conduct feature extraction and is an efficient method for accurate determination of cause. In this paper, the empirical mode decomposition (EMD) thresholding-based de-noising method and probabilistic neural network (PNN) are respectively used in the de-noising of the vibration signal and rotor fault diagnosis and compared with wavelet thresholding-based de-noising technology and back propagation neural network (BPNN). The results show that the clear iterative EMD interval thresholding performs better than wavelet thresholding in the de-noising of the vibration signal, and avoids the determination of wavelet basis and decomposition level. In addition, the PNN created by feature samples does not require training and has a higher accuracy than BPNN.
Adopting method of key block and energy distribution to predict the slope stability under blasting
Authors: Li Qingwen , Chen Lu , Qiao Lan
Published: December 2017

At present, an important slope stability analysis method consists in the evaluation of the bearing capacity of key block, which is located between the joints and fissures in rock mass, and plays the decisive role on the slope stability. Because of the defective equivalent accuracy and elusory mechanical path, the traditional analysis methods have some inevitable errors. However, the energy theory can avoid the above defects easily, in this paper, the analytical input energies are potential energy and blasting vibration energy, and the consumed energies are fractured dissipative energy, friction dissipative energy and kinetic energy of instability. In order to eliminate the size effect problem, it is necessary to emphasize each part of energy expression as the energy density form. And the first four items would be confirmed by different theories and tests, so that the instability kinetic energy could be evaluated by the energy conservation law, and then the instability velocity could be calculated to predict the instability grade of slope.
Influence of support stiffness on aero-engine coupling vibration quantitative analysis
Authors: Qu Meijiao , Chen Guo , Tai Junfei
Published: December 2017

This paper investigates the whole aero-engine coupling vibration, as a rotor tester to be the research object. The rotor tester system is composed of two mountings, stator system, support structures and the rotor system. The modal experiment of the whole tester under the condition of mounting in the test room is carried out. The finite element (FE) model of the rotor tester is built, and the model was modified and validated according to the modal test results. A rotor-stator coupling factor and a section rotor-stator rubbing risk coefficient are proposed, the influence of the support stiffness values on the engine vibration characteristics, such as natural frequencies, modal shapes, rotor-stator coupling degree, and stator-rotor rubbing risk degree at compressor and turbine section is quantitative studied. Results show that the support stiffness contributes to the rigid body modal shapes greatly and to the rotor bending ones slightly. The factor and coefficient defined in this study are both reasonable, and they can reflect the corresponding characteristics exactly. Moreover, the effect of the supports stiffness values on the rotor-stator coupling degree and the rotor-stator rubbing risk degree is nonlinear. The rotor-stator coupling factor and the section stator-rotor rubbing risk coefficient proposed in this study provide a new way to quantitatively research the whole engine coupling vibration.
Load spectrum generation of machining center based on rainflow counting method
Authors: Chen Chuanhai , Yang Zhaojun , He Jialong , Tian Hailong , Li Shizheng , Wang Dongliang
Published: December 2017

Reliability bench tests and probability design method are two important means to improve the reliability of machine tools, while the load spectrum of machine tools is the foundation of reliability bench tests and probability design. According to the load spectrum, the actual working conditions can be simulated in laboratories. A dynamic load spectrum generation method is proposed to establish a representative load spectrum. Firstly, the cutting load measuring system is established based on the characteristics of the cutting loads, and then the actual cutting experiments designed by the orthogonal experimental method are conducted on the basis of the typical cutting conditions in laboratories. Secondly, the counting method of the cutting loads cycles is presented based on the dynamic load characteristics of a machining center. And loads cycles are counted by the proposed counting method, and then a rainflow matrix is formed. Thirdly, in order to improve the precision of the load spectrum the extrapolation of the loads is carried out using the parametric extrapolation method. Then the probability distribution functions of the mean and amplitude of the cutting loads are provided by the K-S goodness-of-fit test method. The case study indicates that the radial force, axial force, and cutting torque of the tested machining center follow gamma, normal, and Weibull distributions with different parameters, respectively. Finally, the joint distribution function of the mean and amplitude of the radial force, axial force, and cutting torque is obtained by using a combination of statistical analysis method, and the two-dimensional load spectrum of the MC is compiled.
Numerical computation for the impact of pantograph angles on the near-field and far-field aerodynamic noises of pantographs
Authors: Tan Jia Wei , Bai Bin , Xu Xiang Yu , Yang Xiao Lei
Published: December 2017

Pantographs are an important part of power supply systems of high-speed trains, whose good working performance is a guarantee for the steady power supply and safety operation of high-speed trains. The aerodynamic drag of pantographs will have negative impacts on the running of high-speed trains. In the meanwhile, the disturbance effect of pantographs on airflow will cause large aerodynamic noises when a high-speed train runs at a high speed. Therefore, this paper conducted a numerical simulation for the flow field and aerodynamic noises of pantographs on the symmetrical plane, compared simulation results with experimental one, verified the correctness of the numerical simulation model, and further studied the impact of pantograph angles on radiation noises. When pantographs were working, cylindrical rods which were vertical to the direction of airflows had a more obvious disturbance effect on airflows and caused a larger range of vortex shedding. Shedding vortexes were mainly distributed at the pantograph head, hinge joints between upper and lower arms, and rear bases. Near-field aerodynamic noises on the longitudinal symmetrical plane of pantographs were distributed at the lower arm, middle hinge joints and bases. The maximum appeared at the middle hinge joints. The intensity of vortexes at the middle hinge joints, lower arms and bases when the pantograph angle was 60° was more than that at other pantograph angles. In this case, the near-field aerodynamic noise of pantographs was more than that of other pantograph angles. In addition, radiation noises of observation points of pantographs in all directions presented an obvious linear relationship. The far-field radiation noise of pantographs was gradually decreased with the increased distance from pantographs. In addition, the far-field radiation noises of pantographs on the same vertical plane had the intensity with the same level.
Effects of misalignment on the nonlinear dynamics of a two-shaft rotor-bearing-gear coupling system with rub-impact fault
Authors: Lu Xin , Zhang Junhong , Ma Liang , Lin Jiewei , Wang Jun , Wang Jie , Dai Huwei
Published: December 2017

In rotor-bearing system, the misalignment can lead to secondary faults, such as the rub-impact fault. How the development of misalignment could affect the rub-impact force and other dynamic responses is important for the vibration control and fault diagnosis of rotor system. In this paper, a mathematical model of a two-shaft rotor-bearing- gear coupling system is established. The model is validated through the misaligned force of gear coupling, the supporting force of the lubricated ball bearing and the whole rotor response. To overcome the limit of traditional approaches and further dig out fault characteristics, the time-frequency method is introduced to analyze the dynamic response from both the time and frequency domains points of view. It is found the misalignment effect on rotor dynamic responses is mainly focused in high rotating speed range. The development of misalignment has an obvious adverse effect on the rotor stability. Some intermittent components in low frequency range due to the occurrence and development of misalignment can be found affecting the rotor stability at low speed range, and the high frequency rub-impact components can be found responsible for the unstable state of rotor.
Dynamic analysis and control of strip mill vibration under the coupling effect of roll and rolled piece
Authors: Liu Zhaolun , Jiang Jiahao , Li Peng , Pan Guixiang , Liu Bin
Published: December 2017

According to the “Hill rolling force formula”, taking particular account of the influence from horizontal vibration of rolled piece in roll gap, a dynamic rolling force model is analyzed. Considering the interaction between vibration of strip and roll, the dynamic vibration model of rolling mill is established. On this basis, the time delayed feedback is introduced to control the vibration of the roll system. The amplitude frequency response of the coupled vibration control equation is obtained by using the multiple scales method. Different time delay parameters are selected to test the control effect. Research results show that the unstable vibration of the roll system can be suppressed with appropriate time delay feedback parameters. Because it is simpler and has good control effect in solving nonlinear mechanical vibration, so these results will make a difference for the research of strip mill vibration, and provide theoretical basis for strip steel production.
Energy absorption characteristics of cement-soil under confining pressure based on SHPB test
Authors: Gao Changhui , Ma Qinyong
Published: December 2017

Cement-soil has been widely used for engineering application. However, no attention has been paid to the energy absorption characteristics of cement-soil under impact loading. In this paper, a series of split Hopkinson pressure bar (SHPB) tests have been conducted to explore the energy absorption characteristics of cement-soil, and the effects of confining pressure (from 0 to 2.0 MPa) and strain rate (from 130 to 172 s-1) on the absorbed energy and the energy absorbency rate are investigated. The results show that the energy evolution of cement-soil under confining pressure is found to be similar at different strain rate. Both the absorbed energy and the energy absorbency rate are influenced by the confining pressure. Moreover, both the absorbed energy and the energy absorbency rate increase at first and then remain stable at a certain value with the increase of confining pressure. In addition, the absorbed energy linearly increases with the incident energy increasing, and a similar tendency is found between the absorbed energy and the strain rate, yet no obvious effect on the energy absorbency rate by the strain rate. Moreover, the energy mechanism of cement-soil is explained from the perspective of failure modes of cement-soil specimen.
A novel MPP-NSGA algorithm and its application in optimization for radiated noises in the aircraft cabin
Authors: Li Jie , Liu Wei Xing , Zhang Yu Zhu , Zhang Ling , Li Shan Shan
Published: December 2017

The paper used the AML method to compute transmission loss of aircraft panels and verifies correctness of the numerical simulation model by experimental test. Finally, this paper used an improved genetic algorithm to conduct a multi-objective optimization for the cabin noise. When the analyzed frequency is less than 250 Hz, transmission loss decreased rapidly with the increased analysis frequency, and decreased from the maximum 63.2 dB to 18.5 dB. Within 250 Hz-4000 Hz, the transmission loss gradually increased with the increased analysis frequency. At 250 Hz, the transmission loss had an obvious valley value. Sound radiation power was then computed based on boundary element method, and panel contribution analysis was conducted to find those panels which had an obvious impact on the cabin noise. Therefore, a multi-objective optimization was conducted on these panels and reinforced ribs. In order to further verify effectiveness of the MPP-NSGA method, it was compared with the traditional GA model and NSGA model. Optimization accuracy using MPP-NSGA model is increased, and optimization time is reduced. Through optimization with traditional GA method, the maximum sound power level decreased by 15.4 %, and the total sound power level decreased by 21.9 %. Through optimization with the NSGA method, the maximum sound power level decreased by 21.7 %, and the total sound power level decreased by 29.0 %. Through optimization with the MPP-NSGA method, the maximum sound power level decreased by 46.3 %, and the total sound power level decreased by 36.0 %. Therefore, compared with other two kinds of genetic algorithms, the MPP-NSGA method is obviously superior in noise optimization in the cabin. In the whole analysis frequency band, noise of the optimized cabin panel at each frequency point was smaller than that of the original structure, fully verifying feasibility of the optimization algorithm proposed in the paper. In addition, in the optimized structure, no panel made obvious contributions to the cabin noise, and each panel showed an equivalent contribution level. Transmission loss of the optimized cabin panel was obviously improved. However, the sound insulation valley still appeared at 250 Hz, but it was not so obvious like the original structure. After optimization, the sound insulation valley was 31.6 dB. The sound insulation valley of the original structure was 18.5 dB. Obviously, the sound insulation valley value of the optimized structure was increased by double compared with the original structure. This paper provided a valuable reference for noise reduction in the aircraft cabin.
An experimental study on the shear property dependency of high-damping rubber bearings
Authors: Oh Ju , Kim Jin Ho , Han Seung Chul
Published: December 2017

This paper investigates the characteristics of high-damping rubber bearings (HDRBs) through various prototype tests. The characteristics were dependent on the displacements, number of load cycles, frequencies, vertical pressure, temperature, shear deformation capability, and vertical stiffness. The prototype tests showed that the displacement was the most influential factor on the characteristics of the HDRB. The effective stiffness and equivalent damping of the HDRB decreased with the displacement and increased with the frequency. The effective stiffness decreased at higher vertical pressure, while the equivalent damping increased. The equivalent damping was more dependent on the vertical pressure than the effective stiffness. The results show that careful examination is required to design the effective stiffness and equivalent damping ratio while considering the dependencies of the design displacement and excitation velocity.
Fault diagnosis of rolling element bearing based on wavelet kernel principle component analysis-coupled hidden Markov model
Authors: Wang Hongchao , Hao Fang
Published: December 2017

Different description results will be obtained when apply hidden Markov model (HMM) to the two different channel signals from the same data collection point respectively. Besides, wrong fault diagnosis result might be obtained because fault feature information would not be described comprehensively by using only one single channel signal. In theory, two channel signals collected form the same data collection point will contain much more fault information than the single channel signal contain, but the coupled phenomenon might occur between the two channel signals. Coupled hidden Markov model (CHMM) is the improved method of HMM and it can fuse the information of two channel signals from the same data collection point efficiently, so much more reliable diagnosis result could be obtained by using CHMM than by using HMM. Stated thus, the fault diagnosis method of rolling element bearing based on wavelet kernel component analysis (WKPCA)-CHMM is proposed: Firstly, use WKPCA as fault feature vectors extraction method to increase the efficiency of the proposed method. Then apply CHMM to the extracted fault feature vectors and satisfactory fault diagnosis result is obtained at last. The feasibility and advantages of the proposed method are verified through experiment.
Study on the experiment and dynamical characteristics of vibrating icebreaking system
Authors: Liu Yang , Zhang Ju Qian , Ma Qiang , Liu Cheng Dong , Wen Bang Chun
Published: December 2017

In view of the design problem of the working amplitude and working frequency of vibrating icebreaking machine, the stiffness and damping value of the ice-snow was identified with the mechanical vibration theory and finite element method. The two-degree-of-freedom mathematical model was established in this paper. And numerical simulation was performed. Then the related icebreaking experiment was carried out. A lot of test and experiment results had proved that experimental data was consistent with the theoretical analysis of mathematical model of vibrating icebreaking system. It was confirmed that the correctness of vibrating icebreaking system’s mathematical model and the rationality of its design could be proved.
Feature extraction method based on VMD and MFDFA for fault diagnosis of reciprocating compressor valve
Authors: Liu Yan , Wang Jindong , Li Ying , Zhao Haiyang , Chen Shuxin
Published: December 2017

Aiming at the nonlinearity, nonstationarity and multi-component coupling characteristics of reciprocating compressor vibration signals, an integrated feature extraction method based on the variational mode decomposition (VMD) and multi-fractal detrended fluctuation analysis (MFDFA) is proposed for a fault diagnosis for a reciprocating compressor valve. Firstly, to eliminate the noise interference, a novel VMD method with superior anti-interference performance was utilized to obtain several components of the quasi-orthogonal band-limited intrinsic mode function (BLIMF) from a strong non-stationarity vibration signal, and a consistent number K of BLIMFs was selected based on a novel criterion for all fault states. Secondly, the MFDFA method, which can describe the multi-fractal structure feature of non-stationary time series, was applied to analyze each BLIMF component, and the parameters of MFDFA were employed as the eigenvectors to reflect the structure characteristics and local scale behavior of the vibration signal. Then, the principal component analysis (PCA) was introduced to refine the eigenvectors for a higher recognition efficiency and accuracy. Finally, the vibration signals of four types of reciprocating compressor valve faults were analyzed by this method, and the faults were identified correctly by pattern classifiers of BTSVM and CNN. Further results comparison with other feature extraction methods verifies the superiority of the proposed method.
Numerical investigation on aerodynamic noises of the lateral window in vehicles
Authors: Chen Ye-gang , Wang Xiang-hong , Zhou Yao-ming
Published: December 2017

The paper firstly conducted a numerical simulation for flow fields and aerodynamic noises of the lateral window region in vehicles, and verified its correctness using the experimental test. Numerical simulation shows that: A pillar has a complicated shape and large corner, so that airflows will be separated here. An eddy structure is caused in the lateral window region and develops along the A pillar to generate serious pressure pulsations. A low pressure region is formed behind the A pillar. Obvious airflow separation regions are in the A pillar, rear view mirrors, wheels and wheel chambers. These airflow separation regions are typical positions causing aerodynamic noises. Additionally, large separated regions are located at the tail part of the vehicle, which is a main reason for causing the aerodynamic resistance. Intensity and velocity of eddies near the lateral window surface are relatively large, while its intensity near edges of the rear view mirror is weak. The shape of eddies extends along the flow direction to be an oval shape. The separated and broken eddies are sources for causing pressure pulsations. According to sound pressures of observation points, it can be also found that the separated eddy is a main reason for causing aerodynamic noises. Sound pressures are low at the right upper corner of lateral windows. In addition, noise distributions on the lateral window become gradually uniform with the increased frequency. In order to reduce flow noises, a bionic saw-tooth structure is applied to A pillars and rear view mirrors. After the bionic structure is introduced, some fluids are adhered to A pillars and rear view mirrors, so that the energy of fluids reaching the lateral window is reduced. In addition, fluids in rear regions of the rear view mirror presented a spiral shape, so that the possibility of fluid diffusion will be also reduced. In the original model, the maximum energy is 57.77, while that in this region with the bionic saw-tooth structures is 55.00. Obviously, the eddy energy is weakened. Compared with the original model, flow noises of all the observation points are reduced to different degrees, and the noise reduction effect is obvious. The results fully prove that this region with bionic saw-teeth in this paper has obvious advantages in noise reduction.
Study on aerodynamic characteristics and running safety of two high-speed trains passing each other under crosswinds based on computer simulation technologies
Authors: Wu Hong , Zhou Zhi-jian
Published: December 2017

With the continuously increased running speed of high-speed trains, aerodynamic problems become more and more obvious. Running safety of trains under crosswinds is a serious problem among numerous aerodynamic problems. Aiming at this problem, this paper combines computational fluid dynamics with multi-body dynamics to study aerodynamic characteristics and safety problems when the high-speed train is running under crosswinds. Based on fluid software FLUENT, this paper computes the flow field of two high-speed trains passing each other under crosswinds. Meanwhile, with combining the multi-body dynamic software SIMPACK with theories, the paper establishes a multi-body dynamic model of the high-speed train, and applies random aerodynamic loads which act on the high-speed train to this model. Impacts of aerodynamic forces (force moments) on aerodynamic characteristics and running safety of each train compartment in the open air are analyzed. Analyzed results show that: when two high-speed trains are passing each other at the same speed of 350 km/h and the crosswind speed is 15 m/s, maximum pressure fluctuations are at observation points near the lateral windows of the head train; aerodynamic forces and force moments of the head train are more than those of the mid-train and tail-train; the high-speed train still has a high safety performance under crosswinds, where the maximum derailment coefficient is 1.9, the reduction rate of the wheel load is 1.1 and the overturning coefficient is 0.98, all of which are smaller than the limit value. More comprehensive factors are considered by the computational model in this paper. It can be used as an effective method to study and evaluate the performance of two high-speed trains passing each other under crosswinds.
Three-dimensional operational modal analysis based on self-iteration principal component extraction and direct matrix assembly
Authors: Zhang Tianshu , Wang Cheng , Zhang Yiwen
Published: December 2017

This paper proposes a self-iteration principal component extraction (SIPCE) and direct matrix assembly method for three-dimensional structures. Different from calculating principal components (PCs) by matrix decomposition in traditional principal component analysis (PCA), SIPCE extracts PCs one by one through self-iteration, so SIPCE has lower space-time complexity. Besides that, it avoids singular-value and ill-posed problems of matrix decomposition. The previous method of solving three-dimensional structures is using modal coordinate response back general reversion of least square algorithm, while the new matrix assembly method calculates three-dimensional modal shapes at one time. So, the new matrix assembly method has less calculation error. The numerical simulation results in a cylindrical shell demonstrate that this method can be practically and effectively applied in operational modal analysis (OMA) of three-dimensional structures. The new method is also robust to noise, and has higher identification accuracy and lower space-time consumption than previous method.
Lifting load monitoring of mine hoist through vibration signal analysis with variational mode decomposition
Authors: Jiang Fan , Zhu Zhencai , Li Wei , Xia Shixiong , Zhou Gongbo
Published: December 2017

Mine hoists play a crucial role in vertical-shaft transportation, and one of the main causes of their faults is abnormal lifting load. However, direct measurement of the load value is difficult. Further, the original structure must be destroyed for sensor installation. To facilitate efficient and accurate monitoring of the lifting load of mine hoist, this paper presents a novel condition-monitoring method based on variational mode decomposition (VMD) and support vector machine (SVM) through vibration signal analysis. First, traditional empirical mode decomposition (EMD) is used to analyze the vibration signal collected by an acceleration sensor, and the number of obtained intrinsic mode functions (IMFs) is employed to set the VMD mode number. Second, the obtained vibration signal is processed by the parameterized VMD, and the useful IMFs of VMD are selected through correlation analysis for feature extraction. Third, the obtained features are used to train an SVM model, and the trained SVM is used to monitor the mine-hoist lifting load. In this study, experiments on an operated mine hoist are also conducted to verify the reliability and validity of the proposed method. The experimental results show that the proposed method can accurately identify the considered lifting load conditions.
Seismic behavior of bifurcated concrete filled steel tube columns with a multi-cavity structure
Authors: Qiao Qiyun , Wu Haipeng , Cao Wanlin , Li Xiangyu , Yang Weibiao
Published: December 2017

In order to meet the architecture and construction needs of high rise buildings, the special-shaped columns are becoming more and more widely used. In this study, cyclic tests on seven special-shaped bifurcated Concrete Filled Steel Tube (CFST) columns are carried out. Test variables are the column cross section types and the loading directions. The strength, ductility, hysteretic behavior, energy dissipation ability, failure modes and seismic mechanisms are analyzed. Test results show that: the cross-section type of the column is the main factor influencing the seismic behavior of the specimens. Compared with the basic cross section type, the strength, ductility and energy dissipation capacity of the strengthened cross section type all significantly increased. The cross sections with the inserted angle steel or circular steel tube have the best comprehensive seismic behavior. Also, the loading direction has a considerable influence on the seismic behavior. Compares with the short axis loading specimen C1-Y, the strength of the long axis specimen C1-X and 45° axis C1-Z increase by 92.5 % and 44.0 %, respectively, indicating that the differences in loading direction should be taken into consideration in the seismic design. Based on the test results, the FEM analysis are also carried out. The FEM results show a satisfactory agreement with experimental results. The concrete constitutive relationship and modelling method proposed is suitable for the simulation of special-shaped bifurcated CFST columns with multiple cavities.
The modal analysis of three-dimension gun barrel using isogeometric analysis and its application to optimization
Authors: Cheng Qingsi , Yang Guolai , Yu Chencheng , Sun Quanzhao
Published: December 2017

In this paper, the Isogeometric Analysis (IGA) is applied to make the modal analysis for 3D gun barrel. The geometry of IGA is modeled by None-Uniform Rational B-Splines (NURBS) which is exact and smooth even at the coarsest mesh level. The first 9 natural frequencies were calculated respectively by IGA and traditional finite element method (ABAQUS), and compared with the test results. The maximum relative error between numerical value and experimental value is less than 3.6 % which verifies the feasibility of numerical model. Six different refinement schemes were analyzed to compare the computational accuracy and efficiency of IGA and ABAQUS. To achieve the credible results, the CPU time of ABAQUS is more than twice of IGA. On this basis, the IGA method is used for the structural shape optimization of gun barrel. The first natural frequency is increased by 6.96 % and the barrel mass is reduced by 4.9 %.
Vibration characteristics and modal analysis of a grinding machine
Authors: Chen Dyi Cheng , Chen Ming Fei , Kang Jing Hao , Lai Chia Chun
Published: December 2017

The machine industry has undergone several developments in the past years, and reducing the cost and time required for machine designing is important. In this study, the vibration characteristics of a precision grinding machine were obtained through experimental modal analysis and finite element analysis. The experimental modal analysis employed single point excitation, and the equipment used to determine the frequency response of the grinding machine comprised a hammer, an accelerometer, and a spectrum analyzer. In addition, the resonance frequency, damping factor, and modal shape of the grinding machine were determined. The natural frequency, modal shape, and interface stiffness were determined through finite element analysis. Finally, the theoretical model and the experimental modal analysis models were compared, and get closer to the actual situation of a model to conduct several times analysis. Thus, this paper presents a reliable and convenient method to study the characteristics of machine tools; this method can reduce unnecessary costs and find structural weaknesses in machine designs for improvement.
Efficient FPGA-based FIR – architecture and its significance in ultrasonic signal processing
Authors: Tiwari Kumar Anubhav , Ostreika Armantas , Platuziene Jurate
Published: December 2017

The presented work demonstrates the most suitable architecture for the FPGA-based signal processing which makes available various real-time filtering algorithms, such as band pass, high pass, low pass, and band-reject for FIR filters. The processor was implemented with the fixed-point arithmetic using VHDL, which can be downloadable on FPGA device. The FPGA device can be interfaced with an analog-to-digital converter (ADC), digital-to-analog converter (DAC) and a personal computer with MATLAB for the user interface and feeding coefficients and order of the filter. The core part of this paper was to find the reconfigurable and efficient architecture of the processor with only one multiplier which can work for Finite Impulse response (FIR) filter with the best- suited structure. The system will be used for automatic generation of fixed-point FIR filters. The model was also implemented in MATLAB script and the verification of results in the case of low-pass filtering confirmed that both models in MATLAB and VHDL matched to each other. All components of architecture in VHDL were designed using generics which allow changing its structure and behavior by generic values. Therefore, it is a universal filter platform where user can process the data while changing the filter parameters as per the requirement of applications. The complete design was verified by taking the example of audio signal frequency, but parameterized components of system architecture can also facilitate its applicability at ultrasonic frequencies by changing the algorithm. The significance and applicability of FPGAs in ultrasonic signal processing were also studied and reviewed.
Seismic fragility analysis of continuous bridges with UDCMEJ under the excitation of seismic sequence
Authors: Wang Jian Guo , Pang Yu Tao , Yuan Wan Cheng
Published: December 2017

Pounding and unseating have been repeatedly observed during severe earthquakes. Residual displacement between adjacent components may have already existed after the mainshock and it will get further destroyed with series of aftershocks. The uniform drift cable-sliding modular expansion joints (UDCMEJ) are constructed by connecting the supporting bars and the fuse boxes with elastic cables avoiding the excessive relative displacement between girders. The seismic analysis of bridges with UDCMEJ under the excitation of seismic sequence is conducted on a continuous beam bridge and a probabilistic assessment is introduced in this study. Conclusions are drawn from comparing fragility curves with and without UDCMEJ. It reveals that the UDCMEJ can avoid pounding between girders and the relative displacement is limited to cables’ free movement. With the contribution of the expansion joints, all of the girders work together and get a balance between displacement and force causing decreased damage probability.
Nonlinear dynamic analysis on maglev train system with flexible guideway and double time-delay feedback control
Authors: Xu Junqi , Chen Chen , Gao Dinggang , Luo Shihui , Qian Qingquan
Published: December 2017

In this paper, the dynamic behavior of time-delayed feedback control for maglev train system with double discrete time delays is considered with flexible guideway. Considering the maglev guideway as Beroulli-Euler beam, the mathematical model of maglev system with flexible guideway is constructed. The time delay of the two state feedback signals in the maglev system occurs simultaneously, and the values are different. The present treatment method only considers one single feedback delay, which are insufficiency. Thus, the Hopf bifurcation with double time-delay feedback of maglev train running on the flexible guideway is analyzed considering time-delayed position feedback signal τ1 and velocity feedback signal τ2. A novel method is presented to develop the double-parametric Hopf bifurcation diagram in relation to τ1 and τ2. Sufficient numerical simulations are provided to illustrate the complex dynamical behavior of the discrete delays τ1 and τ2 for maglev system and we verify the obtained theoretical analysis. Finally, the field experiments are carried out to validate the effectiveness of the Hopf bifurcation analytical method preliminarily.
Active vibration isolation using a six-axis orthogonal vibration isolation platform with piezoelectric actuators
Authors: Wang Shuai , Chen Zhaobo , Jiao Yinghou , Liu Xiaoxiang
Published: December 2017

Piezoelectric actuators (PEA) act an important role in active vibration control area due to the advantages of fast response, high output force, small size and light weight. A 6-axis orthogonal vibration isolation platform based on PEAs is designed, which satisfies the demands of heavy payload, small installation space and multi degree of freedom vibration isolation. The dynamic model of the six-axis orthogonal vibration isolation platform with PEAs is established using Newton-Euler method. With the layout of six PEAs around the axis of symmetry, the dynamic equations could be decoupled into two single-input-single-output (SISO) subsystems and two multi-input-multi-output (MIMO) subsystems. Based on the modal superposition method, the two MIMO subsystems are further decoupled. The control strategy for each SISO system is developed with LQR control method. To evaluate the effectiveness of the control method, the simulation and verification experiment are conducted. The simulation result and experimental data indicate that the decoupling control of the proposed six-axis orthogonal vibration isolation platform with piezoelectric actuators effectively reduces the vibration response of payload within the target frequency range of 20 Hz to 200 Hz.
The effect of lubricant inertia on fluid cavitation for high-speed squeeze film dampers
Authors: Fan Tieshu , Hamzehlouia Sina , Behdinan Kamran
Published: December 2017

This work studies the effect of lubricant inertia on the fluid cavitation for partially sealed high-speed squeeze film dampers (SFDs) executing small amplitude circular-centered orbits (CCOs). The lubricant cavitation is modeled by both the Elrod algorithm and the Gumbel’s cavitation boundary condition to provide the comparison between the most common lubricant cavitation models. Additionally, the fluid inertia is integrated by adapting a finite-length SFD model for partially sealed dampers. The integrated SFD model is incorporated into a numerical simulation model and the results are validated by comparison with experimental data. The results of the analysis demonstrate that the fluid inertia effects significantly extend the cavitation region and influence the cavitation onset and the film reformation.
Accounting Education: The Role of Universities in Imparting Sustainability Accounting Knowledge to the Stakeholders through Industry Linkages
Authors: Onyango Sylvester
Published: December 2017

In the wake sustainability agendas that lead to green growth in the developing countries, the focus has been in the practice and accounting for Social, Environmental and Economic (SEE) activities by both processing and manufacturing organizations. Organizations practice social responsibilities with the view of reaping long term returns or merely complying with regulations, information which is obtained from their annual reports via various media. These reports however, in the purview of knowledge are very scanty and whether the stakeholders understand and are aware of this sustainability accounting information remain very uncertain. However, organizations lack requisite capacity to unfold the elements of sustainability accounting and concurrently develop stakeholder knowledge. This gap remains unbridged since it is debatable how universities shall collate such knowledge and disseminate it to the users of accounting information (stakeholders). Therefore, there is need to develop sustainability accounting knowledge through university industry linkages that will further the realization of sustainability agenda. The paper is based on business sustainability model which looks at sustainability accounting issues. The study was informed by primary data collected from 93 factory unit managers and accountants sampled from 31 tea factories around Mount Kenya region, in testing the relationship between social reporting, environmental reporting, and sustainability accounting in regard to stakeholder theory. The study established significant relationship between the variables (social reporting, environmental reporting and sustainability accounting) and concludes that green growth need to be enhanced through sustainability accounting. In order to foster this, concrete knowledge has to be created by universities that conduct research by linking with industries and disseminate the knowledge to the stakeholders for awareness through stakeholder conferences and publications. The university curriculum need therefore, to incorporate the sustainability issues and passing to the learners too.
DECONSTRUCTION OF TAX AMNESTY IN BASED ON PANCASILA VALUES: THE CASE OF INDONESIA
Authors: Darmayasa I Nyoman , Sudarma I Made , Achsin H.M. , Mulawarman Aji Dedi
Published: December 2017

The main objective of this study is to deconstruct tax amnesty based on Indonesiaâ€™sÂ Principles (Pancasila) values. A post-modern paradigm is used to deconstructÂ current tax amnesty. The methodology used in this research is a combination ofÂ Derridaâ€™s deconstruction and Latifâ€™s thought on historicity, rationality, andÂ actuality. The results show that the initial design of tax amnesty is repatriation,Â which is inferior in the development of taxpayersâ€™ character. Materiality, selfinterest, and measurement object are tax amnesty logos. Religiosity, honesty,Â civility, and mutual cooperation are used in a reverse hierarchy of the beforeÂ mentioned tax amnesty logos. The result of deconstruction is tax amnesty based onÂ Pancasila in order to construct social justice.Tax amnesty is a current issue;Â however, only a limited number of research was dedicated on the philosophy of taxÂ amnesty law. The research offers new meaning to tax amnesty based on PancasilaÂ values which may encourage voluntary tax compliance.
Public Sectorâ€™s Managerial and Financial Accountability
Authors: ISLAMIYAH YUNITA
Published: December 2017

Abstract The aims of this study is to explore the financial and managerial accountability of public sector and its institutionalization. The process of institutionalization was comprehended through the perspective of New Institutional Theory (NIT). The Type of this research is qualitative approach using a case study in The Government of Jombang in Indonesia. The New Institutional Theory (NIT) in organizational studies is related to the fact that the structure of an organization is influenced by the social environment where it is located. Organization has a function to maintain its existence through the process of adaptation or institutionalization. Symptoms of isomorphism occurs where the formal organization similar to the environment through the mechanism of coercive, normative and mimetic. On financial accountability, coercive and normative mechanisms seem to be the most dominant. While on managerial accountability, the coercive mechanisms is the most dominant. Decoupling behavior emerges as a response of the organization in addressing changes in financial and managerial accountability. The response shown in the process of institutionalization of financial accountability is acquiescence and compromise strategy. While, managerial accountability tends to use acquiescence and avoidance strategy. Financial accountability has been institutionalized in everyday practice of organization members. Meanwhile, managerial accountability, is a mere formality for compliance with regulations (ceremonial administrative). The results showed that the mechanism of Reward and Punishment (RNP) from the central government supports the process of institutionalization of accountability.
FACTORS AFFECTING STOCK EXCHANGE INVESTMENT IN KURDISTAN
Authors: Anwar Kofand
Published: December 2017

The purpose of this research is to examine the factors affecting stock exchangeÂ investment in Kurdistan and particularly in Erbil. Developing countries can alsoÂ make use of these markets to develop their economy, though this process could beÂ something new for some developing countries. The stock exchange investment isÂ often the choice for businesses seeking lucrative investment deals. As the placeÂ where monetary transactions are made, investors usually take their chances in theseÂ markets based on studying expected revenues and risks accompanying saidÂ investments. Investors usually avoid high-revenue investments due to the greatÂ risks accompanying them and accept low-risk investments with little revenues. AÂ quantitative method used to analyse the present research. The study was carried inÂ Erbil. The researcher distributed 100 questionnaires, only 71 questionnaires wereÂ received and being completed properly. The researcher used single regressionÂ analysis in order to find factors affecting investment in stock exchange. TheÂ findings revealed that the highest value among all variables was supply & demandÂ factor that influence stock, the second highest value was for economy factor thenÂ the third factor was competition factor and lastly the lowest value was for politicÂ factor. According the findings, it seems that supply and demand play an essentialÂ role in investment in stock exchange in Kurdistan.