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2017, 37(9): .

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2017, 37(9): .

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The Equivalent Constitutive Relationship for Reinforced Concrete Based on Tension-Stiffening

ZHAN Ting-bian, NING Jian-guo, WANG Zhi-hua, REN Hui-lan

2017, 37(9): 881-887. doi:10.15918/j.tbit1001-0645.2017.09.001

Abstract(787) PDF(1194)

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The tension stiffening of concrete affects the stiffness and deflection of reinforced concrete. The equivalent constitutive relationship for reinforced concrete(RC) including three stages was obtained in this paper. The moment of inertia and the distance from the neutral axis to the extreme fiber at the critical points were computed by the transformed section approach. A comparison between the deflections of beams calculated by ACI 318 and Eurocode 2 shows that the predictions by Eurocode 2 are closer to experimental observations. The non-elastic bending theory was used in the first stage, and the elastic modulus was obtained. The method of Eurocode 2 was adopted to calculate the parameters in the cross section in the second and third stages, and the equivalent stress-strain relationship was obtained.

Fluid Shear Mechanical Property Analysis Based on Molecular Dynamic Simulation

ZHAO Xin, YUAN Shi-hua, WEI Chao

2017, 37(9): 888-892. doi:10.15918/j.tbit1001-0645.2017.09.002

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Taking the wall force effect into consideration, a molecular dynamic model for two-paralleled walls-fluid system was built and the related shear process was simulated by changing the tangential motion of wall. Under different wall velocity conditions, the shear mechanical property of fluid level at different positions from wall was studied. And the effects of shear rate, pressure and temperature, on macro shear mechanical property were investigated. Results show that the random thermal motion of molecules can lead to the fluctuation of shear stress for different fluid levels, and with the increase of shear velocity, the fluctuation decreases. In the condition of large tangential velocity of wall, the large velocity slip between surficial fluid and the surface occurs, as responses to the step increase of shear force. Pressure and temperature have great effects on molecular distance, thus increasing pressure or decreasing temperature can decrease distance, as results in the rising for both viscosity and shear force.

Mesoscopic Response Behavior Modeling and Simulation of Heat Resistant Stainless Steel X8CrNi25-21

ZHOU Tian-feng, CHE Jiang-tao, LU Chen-li, LIANG Zhi-qiang, WANG Xi-bin

2017, 37(9): 893-898. doi:10.15918/j.tbit1001-0645.2017.09.003

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Considering the characteristic of heat resistant stainless steel X8CrNi25-21, the classical constitutive model Johnson-Cook (JC) was modified based on plasticity-elasticity mechanics and dislocation dynamics. A constitutive model was established based on the dislocation theory, which could reflect the size effect and mesoscopic response behavior. Based on dislocation pile-up model, some experiments were conducted, including quasi-static tension and SHPB tests, to analyze microscopic parameters such as crystal size and crystal orientation. The objects used in the experiments were of mesoscale nonstandard parts, making corresponding heat treatment process to change sample grain size. The material experiment results show the performance change regularity of microscopic plastic distortion and parting action, and provide parameters for the mesoscopic constitutive model of heat resistant stainless steel X8CrNi25-21.

Modeling and Experimental Investigation on Local Friction Coefficient of Tool-Chip Contact Interface

ZHANG Cheng-yan, LU Ji-ping

2017, 37(9): 899-904. doi:10.15918/j.tbit1001-0645.2017.09.004

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Friction characteristics at the tool-chip contact interface is one of the two main factors affected predictions. The value of friction coefficient which represent contact interface frictional characteristic is difficult to determine due to contact interface in metal cutting involves several complex physical phenomena and it's not a constant parameter for the contact behavior is locally different. This paper aims to identify a friction model to describe the friction coefficient at this interface during the dry cutting based on the stick-slip friction theory. The experiment approach used could reach relevant values of pressures and sliding velocities. Investigations were conducted for quenched and tempered AISI1045 steel in combination with uncoated high speed steel tools. A new friction model has been identified based on normal stress and sliding velocities. The experimental analysis shows change in different degrees caused by the varying of normal stress and sliding velocities.

Exergy Analysis of a Vehicle Waste Heat Recovery System with R123 and R245fa as Working Fluids

SHI Lei, WEI Ming-shan, MA Chao-chen

2017, 37(9): 905-912,918. doi:10.15918/j.tbit1001-0645.2017.09.005

Abstract(688) PDF(992)

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Using experimental data of the heavy-duty diesel engine, the system exergy analysis was carried out for a vehicle waste heat recovery system which was an organic rankine cycle (ORC) with R123 and R245fa as working fluids. Results show that under different engine speeds, the R123 system exergy efficiency increases with the increase of evaporation pressure and engine load, but the increase rate decreases gradually. Under different engine speeds, the R245fa system exergy efficiency increases first and then decreases with the increase of evaporation pressure, and increases with the increase of engine load. An evaporator is the key point to improving the system exergy efficiency. An appropriate evaporator for the system can improve the system exergy efficiency effectively.

Oxidation Reactivity Changes of Diesel Particulate Matter After Being Pre-treated

GAO Jian-bing, MA Chao-chen, XING Shi-kai, SUN Li-wei, HUANG Li-yong

2017, 37(9): 913-918. doi:10.15918/j.tbit1001-0645.2017.09.006

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To evaluate the accuracy of the commonly used method based on thermogravimetric analysis in calculation of the thermal kinetic parameters, particulate matter (PM) was sampled at different engine loads and pre-treated in N₂atmosphere. Indirect evaluation on the influence of pre-treatment on PM kinetic parameters was made based on the analysis of microstructure morphology and nanostructure parameters. Onion-like structures of raw PM and PM aggregation sampled at 80% engine load converted to core-shell like structures, however, it was almost no change for raw PM sampled at 100% load. The diameter of raw PM sampled at 80% load decreased greatly. The mean lattice fringe separation distance decreased for all the three samples and raw PM sampled at 80% load had the largest decrease. For PM aggregation sampled at 80% load and raw PM sampled at 100% load, the mean fringe length changed slightly and mean fringe tortuosity increased greatly, while it was the opposite for raw PM sampled at 80% load. The analysis indicated indirectly that the thermal kinetic parameters of pre-treated samples was different from raw samples.

Effects of the Exhaust System on the Performance of a Turbocharged Diesel Engine

MA Chao-chen, SUN Li-wei, FANG Na, ZHANG Hong

2017, 37(9): 919-925,932. doi:10.15918/j.tbit1001-0645.2017.09.007

Abstract(678) PDF(1712)

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Based on the CA6DL turbocharged diesel engine, the engine model was built in GT-POWER and validated with the test data. Both the MPC exhaust system and constant pressure exhaust system models were built and compared with the three pulse exhaust system. It was indicated that suitable exhaust pipe diameter could not only reduce the fuel consumption of engine but also enhance the power and efficiency of turbine. The result comparisons also show that the three exhaust systems have different influences on the performances of the engine and the turbine. At engine full load conditions, the performance of the engine with the pulse exhaust system is better than the engines with both MPC and constant pressure systems. At the low and medium speed conditions, MPC exhaust system achieves a higher turbine efficiency than the other two exhaust systems.

Modeling and Experiment on Piezostack-Driven Diamond Amplification Jetting System

LU Shi-zhou, ZHOU Feng-qi, REN Chen-liang, LIU Wei, HUANG Bo

2017, 37(9): 926-932. doi:10.15918/j.tbit1001-0645.2017.09.008

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In order to dispense liquids precisely in micro-electronic packaging field, a kind of piezostack-driven diamond amplification jetting system was designed, and an analogous electrical model of the system was constructed based on a lumped parameter method. Then, experiments were carried out to verify the model and its simulation result, and to analyze the effects of system parameters on droplet volume and formation. The results show that, the displacement of the needle can reach 0.3 to 0.5 mm, which is in a suitable range for jetting droplets. For 3 Pa·s viscous liquid, when the driven air-pressure ranges from 0.15 to 0.32 MPa, the droplet volume is positively related to the driven air-pressure. With the increase of viscosity, the droplet volume is reduced, but at the same time, larger driving force is required. The volume can be adjusted by controlling frequency when air-pressure is in a suitable range. The research is of great importance to guide the design of jetting valve and control the droplet disengaging and dispensing accuracy.

Optimizationof Fault-Tolerant Workspace for 7R Redundant Manipulator

FU Tie, ZHU Zhao-hui, DING Hong-sheng, ZHANG Qing-dong

2017, 37(9): 933-936. doi:10.15918/j.tbit1001-0645.2017.09.009

Abstract(566) PDF(751)

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Optimization of fault-tolerant workspace for a 7R redundant manipulator in the condition of single-joint locking was studied systematically. Firstly, the concept of conversion ratio was introduced based on the change rule of the fault-tolerant workspace volume and the relationship consideration between fault-tolerant workspace and locking workspace. And then the redundant manipulator's fault-tolerant workspace was optimized by determining suitable joint's locking range. The study results show conversion ratio increases initially and decreases afterwards as the locking angle increases by two kinds of value method. Meanwhile, the locking angle of highest conversion ratio is also determined.

A On-Line Detection System Development Based on Image Processing for Rubber Hose Defects

ZHU Yan-yan, ZUO Jian-hua, LU Ji-ping, XU Dong-xiao

2017, 37(9): 937-941. doi:10.15918/j.tbit1001-0645.2017.09.010

Abstract(813) PDF(1152)

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A method based on image processing was proposed to realize an online detection of rubber hose surface defects. An image shear method was taken to select hose area. The median filter and Canny edge detection were used to extract graph. To avoid the boundary influence in separating the defects from the hose, a morphological expansion method was used for the defect area separation. According to the character of defects, the defects were classified. Three CMOS cameras within the same plane were layout around the hose axis, interval of 120°. Coaxial light source was used to improve the brightness of hose surface. The mechanical platform of the detection system could adjust the cameras in three directions to ensure the hose in the center position. This system was tested in the hose workshop of Codan-Lingyun Automotive Rubber Hose Co Ltd. The experiment results show that the correct rate of detection is over 96 percent and it can detect the hose surface defects automatically and alarm timely.

Time-Frequency Ridge Manifold Early Fault Warning on Variable Conditions

MENG Ling-xia, XU Xiao-li, XU Yang-mei, WANG Hong-jun

2017, 37(9): 942-947. doi:10.15918/j.tbit1001-0645.2017.09.011

Abstract(703) PDF(791)

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Aiming at the complex working conditions of wind turbine gearbox, a new early fault warning method was proposed based on the Gabor rearrangement logarithmic time-frequency ridges manifold. Firstly, the ridges of Gabor rearrangement logarithmic time-frequency spectrum were extracted and the high dimensional early fault feature vector was built. Then, LTSA (local tangent space alignment) manifold learning method was studied and improved to achieve the reduction of high dimensional feature vector. Finally, the K-nearest neighbor classifier was applied to complete the early fault identification and warning of variable conditional wind turbine gear box. Many experiments were carried out to get verifying data from different condition, including variable speed, load working conditions of planetary gearbox and wind turbine operation filed. The results show that the proposed method can improve the early fault warning accuracy of wind turbine gearbox that works under complex non-stationary conditions, and can provide a reliable basis for predictive maintenance.

Entropic Uncertainty Relations of the Wigner-Ville Distribution in Linear Canonical Transform Domain

ZHUO Zhi-hai, ZHONG Ning, XIE Yan-an, XU Zhan

2017, 37(9): 948-952. doi:10.15918/j.tbit1001-0645.2017.09.012

Abstract(752) PDF(851)

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To investigate the uncertainty principle problems associated with the linear canonical transform, a new kind of entropic uncertainty relation for Wigner-Ville distribution associated with the linear canonical transform domain was derived. Firstly, the Pitt inequality in the linear canonical transform domain was generalized. And then the entropic uncertainty relation for Wigner-Ville distribution associated with the linear canonical transform domain was derived based on the Pitt inequality. The derived results can be taken as the generalization of the classical entropic uncertainty principle in the linear canonical transform domain, and lay the foundation for the theory and application investigation of linear canonical transform.

Generalized Efficient Address Scheme for Arbitrary Point Memory-Based FFT Processors

XIA Kai-feng, ZHOU Xiao-ping, WU Bin

2017, 37(9): 953-957. doi:10.15918/j.tbit1001-0645.2017.09.013

Abstract(933) PDF(576)

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A generalized efficient conflict-free address scheme for arbitrary point memory-based fast Fourier transform (FFT) processor was presented. In the proposed scheme, a high radix decomposition method was utilized to reduce the computation levels and small radix connected multipath-delay-commutator butterfly units were adopted to eliminate the complexity of the computation engine as well. Several important functions of memory-based FFT processor were combined together, including the continuous-flow mode, variable computation size and conflict-free address scheme. Moreover, a prime factor algorithm was employed to decrease the multiplications and the twiddle factor storage when there exist prime factors in the decomposition. At last, a unified Winograd Fourier transform algorithm (WFTA) butterfly core was designed for the small 2, 3, 4, 5 point DFTs to reduce the computation complexity further. Simulation results show that, the power cost of FFT processor can only be 40.8 mW in work frequency 122.88 MHz, it is very suitable for the LTE system.

A Silicon-Based Self-Shielded MEMS Bandpass Filter

DING Ying-tao, LU Wei, YAN Yang-yang

2017, 37(9): 958-963. doi:10.15918/j.tbit1001-0645.2017.09.014

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Basing on coupling coefficient technique and micro-electro-mechanical-system (MEMS) fabrication techniques such as silicon deep reactive ion etching (DRIE), surface metallization and thermal pressed Au-Au bonding, process flows of a self-shielded double-layer interdigital bandpass filter was developed, and a prototype bandpass filter of its kind with open circuit type cross finger structure to be applied to C band was successfully fabricated and tested. Measurement results show that, the center frequency is 3.96 GHz; the frequency error is 2.6%; the insertion loss is 4 dB; the voltage standing wave ratio (VSWR) is below 1.2; the relative is 20.7%; size of the filter device is 7.0 mm×7.8 mm×0.8 mm and the weight is less than 0.1 g. The proposed bandpass filter possesses the advantages of small size, light weight, high performance, low cost, easy to be integrated and being able to be batch produced, adapting to the needs for miniaturization, weight reduction and monolithic integration of filters in microwave and millimeter wave circuits and systems.

Framework of Distributed Storage System and Dynamic Load Balance Technology Based on Bandwidth Condition

HE Zun-wen, SONG Jia, CHEN Hao, GAO Sheng-hua, CHEN Xu-xing, ZHANG Yan

2017, 37(9): 964-969. doi:10.15918/j.tbit1001-0645.2017.09.015

Abstract(889) PDF(1020)

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In the wide-area distributed storage network, the data are stored in different nodes which are extensively distributed. When the data need to be transferred between the nodes, the link bandwidths between different nodes limit the performance of the distributed storage system. To solve this problem, a distributed storage system framework and a dynamic load balance technology were proposed based on link bandwidth conditions. This idea was formed based on the principles of the cloud storage technology and the software defined network (SDN) to realize the separation between the control flow and the data flow. Under this framework, a central control node was established to manage the global network view, including data storage table to record the stored data distribution and current bandwidth situation. When a user application was sent for accessing data, the storage table was used to determine the locations of data. Then the corresponding data nodes were assigned to send data packets according to the routing table. The central control node was used to monitor the bandwidth load situation and dynamically adjust data transmission path. The simulation results verify that the proposed framework and algorithm can effectively solve the scheduling with huge data, reduce the response time, and promote the storage rate.

Speech Bandwidth Extension Based on Codebook Mapping and GMM

WANG Ying-xue, YU Ying-ying, ZHAO Sheng-hui, KUANG Jing-ming

2017, 37(9): 970-974. doi:10.15918/j.tbit1001-0645.2017.09.016

Abstract(620) PDF(759)

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Speech bandwidth extension (BWE) based on the conventional Gaussian mixture model (GMM) often suffers from the overly smoothed problem, and the main reason is the low accuracy of the estimated covariance which results in the loss of specific high frequency feature. Thus, a speech bandwidth extension base on codebook mapping (CM) and GMM was proposed in this paper. Firstly, the feature of low frequency (LF) and high frequency (HF) were extracted, and the GMM model was trained. Then, an offset vector codebook was designed based on the trained GMM parameters. In the reconstruction phase, LF offset vectors were transformed to HF offset vectors according to the trained offset vector codebook. The final HF feature parameter was obtained by adding the HF offset vectors to the estimated part by GMM. It is shown by subjective evaluations and objective evaluations that the CM-GMM significantly overcomes the overly smoothed problem and obviously improves the quality of the synthesized speech signals compared with the conventional GMM-based BWE method.

Stereo Matching Algorithm for Robot Binocular Images in Real Time

ZHANG Zhi, GUO Wen-xian, SU Li, DONG Ran

2017, 37(9): 975-981. doi:10.15918/j.tbit1001-0645.2017.09.017

Abstract(902) PDF(1905)

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For the problem of acquiring binocular vision depth information on a mobile robot platform, a binocular image stereo matching algorithm was proposed for dynamic image sequence. Firstly, a mature semi-global matching algorithm was adopted to carry out the rapid stereo matches of stereo images for the disparity images. On this basis, the major noises encountered during the stereo match process on a mobile platform in a complex environment were analyzed, including the white-spot noise as well as the fault flicker noise. Further, a white-spot filtering algorithm and a disparity image time-domain filtering algorithm were developed respectively to reject the noises. Finally, the experimental verifications were performed. The results show that, the noises coming from stereo matches of dynamic binocular vision images can be effectively suppressed with the proposed algorithms, besides a continuous and clear disparity image sequence can be derived in real-time, which is significant to the obstacle avoidance and the situational awareness of a running mobile robot in a complicated environment.

Improved TFIDF-Based Question Similarity Algorithm for the Community Interlocution Systems

ZHAO Sheng-hui, LI Ji-yue, XU Bi-rong, SUN Bo-yan

2017, 37(9): 982-985. doi:10.15918/j.tbit1001-0645.2017.09.018

Abstract(772) PDF(1462)

Abstract:
To calculate the question similarity in the community interlocution systems, an improved TFIDF algorithm was proposed in this paper. Firstly, the questions were divided into different categories according to the users' retrieval intention, and the weight of every feature word was adjusted based on the distribution in the categories. And then, the topic words were adopted in the feature words for TFIDF algorithm. The experimental results show that, compared with the traditional TFIDF, theP@3 increases 7.66%. Compared with TFIDF-IG, theP@3 increases 5.31%. And different improvements can be obtained inP@5 andP@10. The new algorithm shows better search performance.

Detection of 4 Relative Substances in Clarithromycin by HPLC

SUN Li-quan, ZHANG Meng-nan, MA Bu-fang, YAO Guo-wei, LUO Ai-qin

2017, 37(9): 986-990. doi:10.15918/j.tbit1001-0645.2017.09.019

Abstract(546) PDF(707)

Abstract:
An effective method was established and verified for the detection of clarithromycin and its relative substances J, M, N and K by HPLC. Clarithromycin relative substances sample was separated by isocratic elution with a Purospher STAR LP RP-18e C18 column and with the mobile phase 0.067 mol/L KH₂PO₄solution (pH 4.0)/acetonitrile=60/40, the flow rate of 1.2 mL/min, the column temperature 35℃ and detection wavelength 205 nm, and the separation degrees were greater than 1.2. Analysis results show that, the method can provide good linearity (R>0.999) for all relative substances at the concentration range of 20~240 μg/mL, the average recovery rates keep at 87.80%~121.17%, its operation is simple and efficient, and can be able to simultaneously detect J, M, N and K in clarithromycin.

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