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2016 Vol. 37, No. 1
Published: 2016-01-22
 
1 The Contact Measuring Head of in Dual-probe Atomic Force Microscope
ZHANG Hua-kun,GAO Si-tian,LI Wei
DOI: 10.3969/j.issn.1000-1158.2016.01.01
In order to align two probes of dual-probe atomic force microscope (AFM), it is necessary to establish a measuring head to do in-depth research on the probe A scanning the probe B. Firstly, the mechanical characteristics of the probe are obtained by finite element (FE) simulations. Secondly, using the locked-in amplifier to attain the amplitude and frequency signals to analyze the system resolution (better than 1nm), the probe is rotated 90 degrees compared traditional AFM. Lastly, probe B is scanned by probe A in YOZ plane, reducing the scanning range and scanning step gradually. The alignment accuracy is of 5 nm.
2016 Vol. 37 (1): 1-5 [Abstract] ( 729 ) HTML (25 KB)  PDF (10815 KB)  ( 1903 )
6 Research of the Time Grating Turntable Automatic Calibration System
ZHANG Tian-heng,WANG Pei-yi,WU Liang,SUO Long-bo
DOI: 10.3969/j.issn.1000-1158.2016.01.02
An  automatic  measurement method  is proposed to measur error time grating turntable, identify parameters of model and compensating error. The system adopts home-made numerical control box combining with embedded technology. The high precision grating is used as reference meter, and the double closed-loop control structure is formed with double micro-controller and PC to achieve high-precision positioning system. The undetermined parameters, 8 on poles and 20 within poles, are identified by the Fourier transform, to obtain coefficients of identifying error model  and to realize the real-time online error compensation. Experimental results show that the double closed-loop control system and parameter identification of Fourier transform, can improve the accuracy and the efficiency of calibration, and the accuracy of the time grating turntable is up to 2.4 ″.
2016 Vol. 37 (1): 6-9 [Abstract] ( 507 ) HTML (1 KB)  PDF (1767 KB)  ( 965 )
10 Analysis of the Overall Quantization Error for CORDIC Algorithm in Grating Digital Subdivision
WANG Xiao-na, ZHONG Yu-long,ZHU Wei-bin,YE Shu-liang
DOI: 10.3969/j.issn.1000-1158.2016.01.03
The overall quantization error (EOQ) of CORDIC algorithm is discussed based on grating digital subdivision technique. Simulations and circuit experiments are conducted according to the basic principles of CORDIC. The result shows that the difference between predicted and experimental values is inversely proportional to the number of iteration (n) under the conditions of different binary width (b). The difference between the two reaches 1.8×10-4rad, when n is equal to 12. It proves the effectiveness of the usage of EOQ to value the error of the algorithm in the calculation of angle. A quantitative analysis on error components and key parameters which influence the EOQ is presented. The result shows that the trend of EOQ becomes smaller with the increase of n and b, in which n plays a decisive role in the reduction of EOQ. Circuit test result shows that when the b remains unchanged, EOQ probably decreases by 50% with n adding once. The paper concludes the impact on the angle calculation based on CORDIC caused by EOQ. The conclusion has important significance and practical value to the error analysis in the process of digital subdividing for grating.
2016 Vol. 37 (1): 10-14 [Abstract] ( 944 ) HTML (1 KB)  PDF (1768 KB)  ( 728 )
15 Research on the Verification Method and System of Hand-held Laser Rangefinder
QIAO Wei-dong,ZHAO Min,LIU Kang,LI Qian,FANG Jing
DOI: 10.3969/j.issn.1000-1158.2016.01.04
The existing verification methods of the hand-held laser rangefinder have the problems of large space requirement and many interference factors of outdoor environment. A measurement method of “small space for long distance” is presented and the verification device of hand-held laser rangefinder is developed. The indicating value of a total station is used as length basis. The 50m length is produced indoor on the 16m guide rail by the mirror reflection principle. The environmental influences in outdoor measurement are eliminated. The experimental results show that the verification system can meet the indication error requirements in the verification regulation of “JJG 966—2010” about the hand-held laser rangefinder. The indication error verification of the hand-held laser rangefinder is realized.
2016 Vol. 37 (1): 15-18 [Abstract] ( 773 ) HTML (1 KB)  PDF (417 KB)  ( 897 )
19 One-way Scanning Detection of Paper Currency’s Edge in Class A Currency Counting Machine
LUO Ying, GUO Tao, LIU Lin, HUANG Bing-qun,SONG Yun-cen, YE Yu-tang, LIU Yong
DOI: 10.3969/j.issn.1000-1158.2016.01.05
A real-time one-way scanning edge detection on a field programming gate array with dual-core digital signal processor platform is proposed to meet the high image processing speed needs of 900 paper currency per minute in class A currency counting machine. Real-time one-way scanning edge detection is used instead of usual 4-way scanning edge detection, and the field programming gate array is used to combine the encoding process of one-dimensional edge information with the process of image acquisition. With the dual-core digital signal processor the edge information can be processed in parallel. And so, the efficiency of the edge detection could be improved greatly. The experimental results show the new method can shorten the tens of milliseconds with the 4-way paper currency edge scanning method to microsecond level. The detection efficiency is increased to 50.5 times of the 4-way scanning edge detection method.
2016 Vol. 37 (1): 19-23 [Abstract] ( 621 ) HTML (1 KB)  PDF (670 KB)  ( 511 )
24 Research On The Effects Of Bushing On The Triple Point Of Water
WANG Peng,YAN Xiao-ke,PU Ling,ZHANG Jing-yu,LI Meng,ZHANG Jia-ren
DOI: 10.3969/j.issn.1000-1158.2016.01.06
In order to study the effect of bushing on the triple point of water (TPW), the thermometer well which have diameters of 16 mm and 18mm respectively are developed, and the bushing with diameter of 15.5 mm. The resistance of the standard platinum resistance thermometer in the well with bushing and without bushing are measured, by the AC bridge which the accuracy is 0.02×10-6. The experiment results indicated that the bushing have little effect on the value of TPW, less than 30 μK. Additionally, under the same conditions, the more uniformity between the diameters of bushing and thermometer well, the less influence on the values of TPW.
2016 Vol. 37 (1): 24-26 [Abstract] ( 722 ) HTML (1 KB)  PDF (859 KB)  ( 910 )
27 Theoretical Analysis And Experimental Study Of Thermal Expansion Coefficient Of Copper Wire
LIU Jian-ke,CUI Yong-hong
DOI: 10.3969/j.issn.1000-1158.2016.01.07
The coefficient of thermal expansion of copper of face centered cubic crystal varying with temperature are investigated, and precision instruments DIL402PC thermal expansion instrument measured thermal expansion coefficient of copper in the experiment,that the expansion coefficient of the copper remained in the 2.0836×10-5/℃ between 100℃and 380℃ is founded,which is larger than that of the general measurement of instruments in the laboratory. When it is over 380℃, coefficient of thermal expansion of copper increases linearly with temperature. The results of theoretical analysis and experimental determination remain basically consistent, which results show that the application of this theory can also explain the coefficient of thermal expansion of face-centered structure of other crystal.
2016 Vol. 37 (1): 27-29 [Abstract] ( 689 ) HTML (1 KB)  PDF (283 KB)  ( 1750 )
30 Research on Reproducibility and Temperature Plateaus for Fe-C Eutectic Point
LV Guo-yi,LIU Yu-sheng,YANG Yong-jun
DOI: 10.3969/j.issn.1000-1158.2016.01.08
Above the freezing point of copper (1084.62 ℃) in the current temperature calibration system, there is no other pure metal fixed point. But the metal-carbon eutectic points, as a new type of fixed points with excellent reproducibility, add temperature fixed points above the freezing point of copper and develop the current level of high temperature measuring value transfer. Although the Fe-C eutectic point is very close to the freezing point of copper, it is still very useful to provide valuable experience for the perfusion and repetition of higher eutectic points. A one-class standard S-type thermocouple is used for measuring the temperature plateaus of Fe-C eutectic point, and the eutectic point temperatures fluctuate is in the range of 1152.4~1152.5 ℃.
2016 Vol. 37 (1): 30-33 [Abstract] ( 770 ) HTML (1 KB)  PDF (1816 KB)  ( 481 )
34 The On-line Measurement of Surface TemperatureBased on High Emissivity Target
WANG Ze-yao,CHEN Le,FU Ya-qiong,WU Yun-xia,XU Jian-bin
DOI: 10.3969/j.issn.1000-1158.2016.01.09
In some industrial fields, surface temperature measurement requires speed and accuracy. Using infrared thermometer to measure temperature directly is fast, but the accuracy is low. Based on a target of high emissivity, a method of measuring the surface temperature fast and accurately is proposed. The target which made by high emissivity paint can help eliminate the surface emissivity effects on the accuracy of infrared temperature measurement when used in site. At the same time, the influence of ambient temperature, atmospheric temperature, measuring distance, atmospheric attenuation and other factors can be eliminated by comparing the direct measurement and target measurement results. Experimental results and theoretical analysis show that the proposed method can effectively improve the accuracy of infrared surface temperature measurement and the average error of the method is lower than 1%.
2016 Vol. 37 (1): 34-37 [Abstract] ( 538 ) HTML (1 KB)  PDF (1574 KB)  ( 421 )
38 Numerical simulation of the magnetic field of rectangular and saddle coils in electromagnetic flowmeter
DU Sheng-xue,KONG Ling-fu,LI Ying-wei
DOI: 10.3969/j.issn.1000-1158.2016.01.10
The distribution of magnetic fields generated by the rectangle and saddle exciting coils that are used for electromagnetic flowmeter is discussed. Using Biot-Savart law and superposition principle, the distribution of magnetic field on the cross section containing electrodes inside the measuring tube is obtained by numerical simulation. Two indicators direction parallel degree and uniform degree of magnetic field intensity was proposed to represent the magnetic field distribution uniformity. Analysis and optimization for the magnetic field generated by different sizes of rectangular and saddle exciting coils are separately done based on above two indexes, and further comparative analysis to the magnetic field generated by the two kinds of shape coils has been made.
2016 Vol. 37 (1): 38-42 [Abstract] ( 732 ) HTML (1 KB)  PDF (1669 KB)  ( 815 )
43 Vibration Torque Measurement and Suppression Method for Brush DC Motor
ZENG Hua,FENG Hao,ZHAO Hao
DOI: 10.3969/j.issn.1000-1158.2016.01.11
Seen from the air-gap magnetic field distribution of the commutation process, vibration torque of brush DC motor exists. Aiming at the DC motor shaft vibration torque, specifically analyzed from the cause to the theoretical analysis and experimental measurements, a theoretical analytic method and an experimental measurement method are proposed. At the same time, based on the theoretical analysis and experimental measurements, a supression method of vibration torque is proposed. Through the experiment, it is found that the analytical results consistent with the experimental results. This proves the effectiveness of the method.
2016 Vol. 37 (1): 43-46 [Abstract] ( 593 ) HTML (1 KB)  PDF (351 KB)  ( 634 )
47 Optimal Control in Cold Rolling Hydraulic Automatic Position System Based on RBF Neural Network with Memory Factor
WEI Li-xin, ZHENG Cui-hong, LI Ying, WANG Hong-rui
DOI: 10.3969/j.issn.1000-1158.2016.01.12
Aiming at the characteristics for cold rolling hydraulic aotomatic positom control system with multi-variable, strong coupling, higher order and time-varying, a radial basis function neural network introduced in memory factor is proposed which can adaptive tune PID parameters online.To improve network accuracy, improved shuffled frog leaping algorithm is used to offline fully optimize radial basis fanction neural network with memory factor, which can obtain the network structure and initial parameters simultaneously, and avoid the tedious network model training. And the test functions are applied to demonstrate the optimized network has good approximation ability.Then the optimized radial basis fanction neural network with memory factor that has self-correction function is used to finely tune PID parameters online, and simulation results show that the control system with fast track, small overshoot, strong adaptability is better than the traditional PID control and general radial basis function neural network PID control methods, which has practical value.
2016 Vol. 37 (1): 47-52 [Abstract] ( 636 ) HTML (1 KB)  PDF (572 KB)  ( 377 )
53 Study on Aluminum Hot Rolling Model of Friction Coefficient Based on Improved Fish Swarm Algorithm
SUN Hao, YANG Jing-ming,HU Zi-yu, CHE Hai-jun, HAN Le
DOI: 10.3969/j.issn.1000-1158.2016.01.13
In the level 2 process automation of hot rolling,there is a problem of low forecast accuracy of friction coefficient in the deformation zone. A quantitative relationship between the oil film thickness, the rolling temperature and the coefficient are analyzed. The model of friction coefficient which is more suitable for the scene of the rolling is established through the improved artificial fish swarm algorithm. The above model is applied to the aluminum strip machine and the results show that the new model improved the soft measurement precision of the friction coefficient, the stability of rolling and played a reference role in the other model base on the model of the friction coefficient.
2016 Vol. 37 (1): 53-55 [Abstract] ( 580 ) HTML (1 KB)  PDF (306 KB)  ( 712 )
56 Rolling Bearing Fault Diagnosis Based on Differential-based Empirical Mode Decomposition and Fuzzy Entroy
MENG Zong,JI Yan,YAN Xiao-li
DOI: 10.3969/j.issn.1000-1158.2016.01.14
A comprehensive rolling bearing fault diagnosis method combining differential-based empirical mode decomposition (DEMD) with fuzzy entropy and support vector machine(SVM) is proposed.Firstly, mechanical vibration signal is decomposed with differential-based empirical mode decomposition (DEMD) to obtain a certain number of intrinsic mode functions (IMFs) that have physical meaning. With a mutual relationship rule, the IMF components that have largest correlation coefficients with the original signal are sifted out. The fuzzy entropies of these IMFs are calculated and use as eigenvectors of fault signals, then the eigenvectors are put into SVM to identify the state of the rolling bearing. Compared with the method based on empirical mode decomposition (EMD) combined with fuzzy entropy and SVM, the experimental results show that the method of mechanical failure signals can accurately identify classification effectively.
2016 Vol. 37 (1): 56-61 [Abstract] ( 760 ) HTML (1 KB)  PDF (2585 KB)  ( 574 )
62 Study on rotating machinery fault diagnosis method based on envelopes fitting algorithms EMD
SHI Pei-ming,WANG Jing,WEN Jiang-tao,TIAN Guang-jun
DOI: 10.3969/j.issn.1000-1158.2016.01.15
Aiming at the problems of the end effects and the overshoot and undershoot during envelope fitting in empirical mode decomposition, a new method is proposed by using piecewise Hermite interpolation to solve the overshoot and undershoot problems.Combining with the extreme point extension window function, the end effects problem is solved based on slope re-optimization.The results are that the envelope fitting is optimized, the IMFs are more accurate, the Hilbert spectrum and boundary spectrum are also more accurate by Hilbert transform and finally the quality of EMD algorithm is improved.The simulations and the rolling bearing fault diagnosis case show that the new method has a good effect and can effectively diagnose rotating machinery faults.
2016 Vol. 37 (1): 62-66 [Abstract] ( 706 ) HTML (1 KB)  PDF (3594 KB)  ( 633 )
67 A Bearing Fault Diagnosis Method Based on EEMD-SVD and FCM Clustering
ZHANG Li-guo,KANG Le,JIN Mei,LI Pan
DOI: 10.3969/j.issn.1000-1158.2016.01.16
A new method for diagnosis based on ensemble empirical mode of decomposition(EEMD), singularity value decomposition(SVD) and fuzzy C-means clustering(FCM) is proposed. First of all, the mechanical vibration signals were decomposed by EEMD into a certain number of intrinsic mode functions (IMFs). Secondly, IMF components were chosen by the criteria of mutual correlation coefficient and got several component containing the main information of signals, then , with the SVD method ,singular value sequences were obtained. At last, the constructed eigenvector were put into the FCM fuzzy clustering classifier to recognize different fault types. The results of experiment and engineering analysis demonstrate that the method proposed is able to diagnose mechanical faults accurately and effectively.
2016 Vol. 37 (1): 67-70 [Abstract] ( 655 ) HTML (1 KB)  PDF (4988 KB)  ( 669 )
71 Rolling Force Prediction Based on Support Vectors Machine with  Particle Swam Optimization
YANG Jing-ming,CHEN Wei-ming,CHE Hai-jun,LV Jin,JIA Lin
DOI: 10.3969/j.issn.1000-1158.2016.01.17
In order to improve the prediction accuracy of rolling force in hot rolled strip, combined with particle swarm optimization algorithm and support vector machine method to predict the rolling force, According to the principle of rolling, rolling force prediction model is established by using SVM, the parameters of SVM was optimized by particle swarm algorithm to improve the prediction accuracy. In order to further improve the precision of rolling force prediction, network based on SVM combined with mathematic model method is proposed. The acquisition of a large number of rolling data offline simulation was based on a “1 + 4” aluminum strip rolling factory. The simulation results can be seen that rolling force predicted the method of network based on SVM combined with mathematic mode, improves the speed of rolling force prediction and makes the forecast accuracy of rolling force control within 7%.
2016 Vol. 37 (1): 71-74 [Abstract] ( 648 ) HTML (1 KB)  PDF (383 KB)  ( 602 )
75 Application Status of Nondestructive Testing Technology Based on the Barkhausen Effect
YUAN Hui-juan,FU Jian,LI Hong-mei,LI Jun-zhong, JIANG Xue,YANG Ying,ZHANG En-jing
DOI: 10.3969/j.issn.1000-1158.2016.01.18
Nondestructive testing technology based on the Barkhausen effect can be used to detect stress, hardness, grain size, grinding burn etc., it gets the attention because of its advantages, such as rapid, not-destructive and quantitative.The research status of Barkhausen effect is reviewed. Its application situation were investigated that the nondestructive testing technology based on the Barkhausen effect on stress, hardness, grain size, grinding burn detection etc., and the relationship between the MBN signals and stress, hardness, grain size, grinding burn were showed.The key points to design the MBN sensor are described.
2016 Vol. 37 (1): 75-78 [Abstract] ( 716 ) HTML (1 KB)  PDF (502 KB)  ( 742 )
79 A New Improved Orthogonal Correlation Method of Measuring Impedance Angle of Ultrasound Transducer
JI Hua-wei,LI Xu-long,HU Xiao-ping
DOI: 10.3969/j.issn.1000-1158.2016.01.19
During the ultrasonic cutting of the cellular composite, the failure of the match between ultrasonic and impedance of transducer leads to the reduce of the quality and efficiency of machining of materials, and even damages ultrasound equipment. The key to solve this problem is that realize the dynamic matching by detecting impedance angle on line and in real time. Based on the relevant principles of orthogonal, a new method to detect the impedance angle is proposed, which is independent with whether to synchronize with the sampling. And this way realizes the on-line detection of impedance angle by using the microprocessors and sensor measuring circuit. Simulation and experiments show that the method is suitable for synchronous and asynchronous sampling of ultrasound signal frequency and lays the foundation for the realization of dynamic matching. Besides, this method needs the small amount of calculation, is real-time and has high accuracy, and specially after the improvements, its error closes to 0.0551°.
2016 Vol. 37 (1): 79-83 [Abstract] ( 564 ) HTML (1 KB)  PDF (969 KB)  ( 487 )
84 Supplementary Comparison of Free-field Hydrophone Calibrations in the Frequency Range 250 Hz to 8 kHz
CHEN Yi,PING Zi-hong,A E Isaev,A N Matveev
DOI: 10.3969/j.issn.1000-1158.2016.01.20
A description is given of the results of COOMET.AUV.W-S1 supplementary comparison of free-field hydrophone calibration in the frequency range 250 Hz to 8 kHz between Hangzhou Applied Acoustics Research Institute – a pilot and Russian National Research Institute for Physicotecnical and Radio Engineering Measurements. Two standard hydrophones of TC 4033 and GI 55 were calibrated in this comparison. Reciprocity and comparison methods, their calibration facilities were used to assess the current state of free-field hydrophone calibration in low frequencies. The results indicate that the sensitivities of two hydrophones calibrated by China and Russia have good consistency.The deviations at most frequncies between the sensitivites and their reference values are less than 0.40 dB,the maximum deviation is 0.59 dB.The results prove that the lowest frequency of free-field hydrophone calibration of China and Russia can be extended to 250 Hz.
2016 Vol. 37 (1): 84-89 [Abstract] ( 610 ) HTML (1 KB)  PDF (2543 KB)  ( 663 )
90 Power Quality Disturbance Identification Based on LMD Energy Entropy and GK Fuzzy Clustering
ZHANG Shu-qing,LI Pan,FENG Lu,LI Nan,ZHANG Hang-fei,QIAO Yong-jing,XU Jian-tao
DOI: 10.3969/j.issn.1000-1158.2016.01.21
A new approach for power quality disturbance identification based on local mean decomposition (LMD) energy entropy and GK fuzzy clustering is introduced. LMD energy entropy has localized features and can represent the complexity of disturbance signals, quantizing disturbance characteristic. GK fuzzy clustering can process data with irregular distribution, so as to identify various disturbance signals. Non-stationary disturbance signals are decomposed by LMD, obtaining a number of product function (PF) components with physical meaning, which is screened out by Shannon entropy feature selection methods to obtain the energy entropies and construct the eigenvectors. The constructed eigenvectors are further put into GK classifier to recognize different identification types. The experiment demonstrated that the method is able to identify disturbance signals accurately, with better anti-noise performance.
2016 Vol. 37 (1): 90-95 [Abstract] ( 585 ) HTML (1 KB)  PDF (1761 KB)  ( 543 )
96 A Novel Fast Convergence LMS Harmonic Detection Algorithm
GUO Rui,LI Bao-hua,MA Ao-yun
DOI: 10.3969/j.issn.1000-1158.2016.01.22
Aiming at the problem between convergence speed and steady-state accuracy of traditional fixed step size LMS algorithm for harmonic detection, a improved variable step size LMS harmonic detection algorithms with higher convergence speed is presented.This algorithm used autocorrelation estimate of the error signal e(n), e(n－1) in the same phase in two adjacent time to adjust step size, and used normalization method , the k(n) and k(n－1) are as new feedback, which k(n) and k(n－1) are the proportion of the error signal in the total current signal, then using coherence average estimate of the feedback amount to control the step size updating; by introducing the disturbance of the absolute estimation error to update the tapping vector of the self-adaptive filter in weight iteration formula. Finally, MATLAB/Simulink simulation and experimental results show that the method compared to conventional fixed step size LMS harmonic detection algorithm has good performance on the convergence speed and steady-state accuracy, especially the method has good tracking performance in load mutation.
2016 Vol. 37 (1): 96-101 [Abstract] ( 518 ) HTML (1 KB)  PDF (3373 KB)  ( 389 )
102 Field coil constant frequency response measurement
ZHANG Wei,TANG Yuan-hui
DOI: 10.3969/j.issn.1000-1158.2016.01.23
The coil constant is an important parameter of field coil. Analysis of the causes of coil constant frequency response, puts forward measurement method based on the induction coil, and uses the measurement of relative ratio to eliminate the measurement error. The three section of the Bakel ring magnetic field frequency response measurement results show that, the results of theoretical analysis of the method is consistent with the actual measured results.
2016 Vol. 37 (1): 102-104 [Abstract] ( 588 ) HTML (1 KB)  PDF (1717 KB)  ( 483 )
105 The Round-off Uncertainty Evaluation of Fast Fourier Transform
JING Xue-dong,CHEN Zhi,ZHANG Zhi-hui,HUANG Wei-lin
DOI: 10.3969/j.issn.1000-1158.2016.01.24
Round-off uncertainty is an important source of the uncertainty evaluation for fast Fourier transform algorithm. The fast Fourier transform algorithm expression is transformed into vector matrix, then the matrix will decompose into sparse matrix. So the signal flow graph will determine and round-off uncertainty in every level of the transmission form will be obtained. Assuming round-off uncertainty distribution as uniform distribution, then the round-off uncertainty of radix-2FFT by type B evaluation of GUM can be evaluated, finally the values of round-off uncertainty after passing through the algorithm will be obtained. Based on this, a unified method for the evaluation of the uncertainty of FFT can be established.
2016 Vol. 37 (1): 105-108 [Abstract] ( 644 ) HTML (1 KB)  PDF (2049 KB)  ( 958 )
109 Perspective on Some Terminology of Evaluation of Flow Measurement Uncertainty
SHEN Yu-ming,ZHANG Jin-ming
DOI: 10.3969/j.issn.1000-1158.2016.01.25
According to the VIM(3th),JJF 1001—2011and JJF 1059.1—2012, further comments have been made, and different views and proposed changes put forward as to several terms, definitions, notes in ISO/TR7066-1(1997), ISO5168(2005) and GB/T 29820.1—2013. Detailed analysis have been made on “random error”, “systematic error”, “standard deviation and variance”, “uncertainty and evaluation of measurement uncertainty”, “repeatability conditions”, “sensitivity”, and “calibration linear equation” in all above documents.
2016 Vol. 37 (1): 109-112 [Abstract] ( 591 ) HTML (1 KB)  PDF (302 KB)  ( 748 )
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