2015 Vol. 30, No. 2
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2015, 30(2)
:1-5.
doi: 10.3969/j.issn.2095-476X.2015.02.001
Abstract:
The volatile components in modified polysulfide rubber were analyzed by headspace-gas chromatography-mass spectrometry. The sample amount,injection volume, inlet temperature of gas chromatography(GC) conditions were optimized using the orthogonal test method, and the equilibrium temperature and equilibrium time of the headspace(HS) sampling were optimized. The results showed that under such GC conditions as sample amount of 0.1 g,injection volume of 1.0 mL, the inlet temperature of 250℃, using such HS conditions as equilibrium temperature of 90℃, equilibrium time of 20 min,and combination of NIST MS Library search and literature retrieva, 4 kinds of volatile compounds, which recognized as the thiirane, mercaptoethanol, two butyl ether and dibutyl phthalate were idetified. Using ethylene glycol as the internal standard, the 4 kinds of main volatile components relative content of the modified polysulfide rubber products from 6 different production conditions were located in 0~3.633 1 mg/g with the relative standard error(RSD) was 2.52%~6.56%. This method had good repeatability.
The volatile components in modified polysulfide rubber were analyzed by headspace-gas chromatography-mass spectrometry. The sample amount,injection volume, inlet temperature of gas chromatography(GC) conditions were optimized using the orthogonal test method, and the equilibrium temperature and equilibrium time of the headspace(HS) sampling were optimized. The results showed that under such GC conditions as sample amount of 0.1 g,injection volume of 1.0 mL, the inlet temperature of 250℃, using such HS conditions as equilibrium temperature of 90℃, equilibrium time of 20 min,and combination of NIST MS Library search and literature retrieva, 4 kinds of volatile compounds, which recognized as the thiirane, mercaptoethanol, two butyl ether and dibutyl phthalate were idetified. Using ethylene glycol as the internal standard, the 4 kinds of main volatile components relative content of the modified polysulfide rubber products from 6 different production conditions were located in 0~3.633 1 mg/g with the relative standard error(RSD) was 2.52%~6.56%. This method had good repeatability.
2015, 30(2)
:6-10.
doi: 10.3969/j.issn.2095-476X.2015.02.002
Abstract:
The polycrystalline Ca(1-x)YxCu3Ti4O12(x=0,0.005,0.010,0.015,0.020,0.030,0.040) ceramics samples were prepared by traditional solid-state reaction method. The microstructure and nonohmic properties were characterized by X-ray diffraction,scanning electron microscope and the high-voltage digital source-meter. The effect mechanism of the variation in grain boundary barrier on the non-ohmic properties was also discussed. The results presented that there was no phase transition in Y3+-doped CaCu3Ti4O12 samples,while the grain growth was related to the doping content. Both the density and chemical environment in grain boundary of samples were influenced by doping. The non-ohmic properties of CaCu3Ti4O12 ceramics material were modified by Y3+ doping,and both non-linear coefficient and breakdown voltage were apparently enhanced by doping with the appropriate content(x=0.010~0.020).
The polycrystalline Ca(1-x)YxCu3Ti4O12(x=0,0.005,0.010,0.015,0.020,0.030,0.040) ceramics samples were prepared by traditional solid-state reaction method. The microstructure and nonohmic properties were characterized by X-ray diffraction,scanning electron microscope and the high-voltage digital source-meter. The effect mechanism of the variation in grain boundary barrier on the non-ohmic properties was also discussed. The results presented that there was no phase transition in Y3+-doped CaCu3Ti4O12 samples,while the grain growth was related to the doping content. Both the density and chemical environment in grain boundary of samples were influenced by doping. The non-ohmic properties of CaCu3Ti4O12 ceramics material were modified by Y3+ doping,and both non-linear coefficient and breakdown voltage were apparently enhanced by doping with the appropriate content(x=0.010~0.020).
2015, 30(2)
:11-15,21.
doi: 10.3969/j.issn.2095-476X.2015.02.003
Abstract:
ZnWO4 materials were prepared by citrates sol-gel method. The effect of sintering temperature on preparation process of samples was studied. The thermo-decomposing process of the precursor was analyzed by TG/DSC; the crystal structure and morphology of samples were characterized by XRD and SEM, and the electrochemical performance was tested by continuous current charge-discharge, cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). The results showed that the materials prepared at 550℃ had well developed crystal structure and better electrochemical properties with the first discharge specific capacity of 446.29 mAh/g and the reversible specific capacity of 200.7 mAh/g after cycle 20 times, specific capacity decayed slowly, charge and discharge efficiency was also high, and it showed a good cycle performance.
ZnWO4 materials were prepared by citrates sol-gel method. The effect of sintering temperature on preparation process of samples was studied. The thermo-decomposing process of the precursor was analyzed by TG/DSC; the crystal structure and morphology of samples were characterized by XRD and SEM, and the electrochemical performance was tested by continuous current charge-discharge, cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). The results showed that the materials prepared at 550℃ had well developed crystal structure and better electrochemical properties with the first discharge specific capacity of 446.29 mAh/g and the reversible specific capacity of 200.7 mAh/g after cycle 20 times, specific capacity decayed slowly, charge and discharge efficiency was also high, and it showed a good cycle performance.
2015, 30(2)
:16-21.
doi: 10.3969/j.issn.2095-476X.2015.02.004
Abstract:
Based on the studies of the vascular tree's simulation and combined with the mixed bio-heat transfer model,the traditional Pennes bio-heat transfer equation was improved by using the blood perfusion considering the local heat transfer between the blood and the tissue. COMSOL Multiphysics was used to simulate,and the results of Pennes equation improved before and after were compared. The results showed that the improved Pennes equation could reflect the local influence of the vascular tree on organization's regional temperature distribution, while the traditional Pennes equation only described the homogeneous form of tissue temperature distribution.
Based on the studies of the vascular tree's simulation and combined with the mixed bio-heat transfer model,the traditional Pennes bio-heat transfer equation was improved by using the blood perfusion considering the local heat transfer between the blood and the tissue. COMSOL Multiphysics was used to simulate,and the results of Pennes equation improved before and after were compared. The results showed that the improved Pennes equation could reflect the local influence of the vascular tree on organization's regional temperature distribution, while the traditional Pennes equation only described the homogeneous form of tissue temperature distribution.
2015, 30(2)
:22-25.
doi: 10.3969/j.issn.2095-476X.2015.02.005
Abstract:
The mature male mouse suffered by one-month,three-month and five-month passive smoking by using the established passive smoking model,comparing with normal control male mouse,the expression rule of AKAP3 in the passive smoking male mice testicular tissue was analyzed by RT-PCR. The results showed that one-month passive smoking male mouse had greater AKAP3 mRNA expression quantity than that of control male mouse. However,no significant differences were observed among three-month and fivemonth passive smoking male mouse. The results of this study provided theoretical basis and reference for further study of AKAP3 in male mice reproduction function.
The mature male mouse suffered by one-month,three-month and five-month passive smoking by using the established passive smoking model,comparing with normal control male mouse,the expression rule of AKAP3 in the passive smoking male mice testicular tissue was analyzed by RT-PCR. The results showed that one-month passive smoking male mouse had greater AKAP3 mRNA expression quantity than that of control male mouse. However,no significant differences were observed among three-month and fivemonth passive smoking male mouse. The results of this study provided theoretical basis and reference for further study of AKAP3 in male mice reproduction function.
2015, 30(2)
:26-29,41.
doi: 10.3969/j.issn.2095-476X.2015.02.006
Abstract:
Recombinant glucosidase was used to catalysis biosynthesize of aloe-emodin through aloin. Single factor experiment and uniform design were used to optimize the biosynthesize conditions. As the result,the optimal conditons of aleo-emodin's biosynthesis were as following: reaction time 4 h,combinant glucosidase concentration 50 U/mL,the ratio of tert-butanol and water 5:5(v/v),reaction temperature 43℃,and pH value 5.2. Under those conditions,the highest yield was 92.18%.
Recombinant glucosidase was used to catalysis biosynthesize of aloe-emodin through aloin. Single factor experiment and uniform design were used to optimize the biosynthesize conditions. As the result,the optimal conditons of aleo-emodin's biosynthesis were as following: reaction time 4 h,combinant glucosidase concentration 50 U/mL,the ratio of tert-butanol and water 5:5(v/v),reaction temperature 43℃,and pH value 5.2. Under those conditions,the highest yield was 92.18%.
2015, 30(2)
:30-33.
doi: 10.3969/j.issn.2095-476X.2015.02.007
Abstract:
Using the single factor and orthogonal experiments with the flue-cured tobacco varieties of zhongyan100 as raw material and two SCAR primers to study the multiple PCR reaction system in the interaction between the main ingredients of flue-cured tobacco leaves,the best suitable multiple PCR reaction system was established for roast tobacco including DNA template 45 ng, Mg2+ concentration 2.50 mmol/L, dNTP concentration 0.40 mmol/L and Taq enzyme dosage 4.00 U on the 20 μL system. The stripe of the system is clear and it can shorten the identification time, laying a foundation for using multiple PCR technology to identify flue-cured tobacco varieties.
Using the single factor and orthogonal experiments with the flue-cured tobacco varieties of zhongyan100 as raw material and two SCAR primers to study the multiple PCR reaction system in the interaction between the main ingredients of flue-cured tobacco leaves,the best suitable multiple PCR reaction system was established for roast tobacco including DNA template 45 ng, Mg2+ concentration 2.50 mmol/L, dNTP concentration 0.40 mmol/L and Taq enzyme dosage 4.00 U on the 20 μL system. The stripe of the system is clear and it can shorten the identification time, laying a foundation for using multiple PCR technology to identify flue-cured tobacco varieties.
2015, 30(2)
:34-37.
doi: 10.3969/j.issn.2095-476X.2015.02.008
Abstract:
Radix Codonopsis was used as raw materials, the extraction yield as the index, to investigate effects of the ethanol concentration, extraction time, and the ratio of solid and liquid on the ultrasonic extraction by single factor experiment and orthogonal lexperiment. And the volatile components of the extract were analyzed by GC-MS. The results showed that the extraction yield reached 52.88% on the optimization condition: ethanol concentration(v/v) 50%,extraction time 40 min and the ratio of solid and liquid(w/v) 1:10,39 kinds of volatile components were identified from it,higher constituents were furfural, stearyl alcohol acetate,5-methyl-2-furaldehyde,octacosane,etc.,which were different from the constituents of the extract by steam distillation and by simultaneous distillation extraction.
Radix Codonopsis was used as raw materials, the extraction yield as the index, to investigate effects of the ethanol concentration, extraction time, and the ratio of solid and liquid on the ultrasonic extraction by single factor experiment and orthogonal lexperiment. And the volatile components of the extract were analyzed by GC-MS. The results showed that the extraction yield reached 52.88% on the optimization condition: ethanol concentration(v/v) 50%,extraction time 40 min and the ratio of solid and liquid(w/v) 1:10,39 kinds of volatile components were identified from it,higher constituents were furfural, stearyl alcohol acetate,5-methyl-2-furaldehyde,octacosane,etc.,which were different from the constituents of the extract by steam distillation and by simultaneous distillation extraction.
2015, 30(2)
:38-41.
doi: 10.3969/j.issn.2095-476X.2015.02.009
Abstract:
In order to study the pyrolysis behavior of Lycium barbarum L. polysaccharide and influence on the cigarette sensory quality,the polysaccharide was extracted by water extraction and alcohol precipitation method. The pyrolysates were analyzed in different atmosphere(10% O2 and 90% N2) and at temperature levels(300℃,600℃, 750℃ and 900℃). The pyrolysates were directly introduced into Py-GC-MS spectrometer, quantitative analysis was made by area normalization. The results showed that cigarette sensory quality was improved by polysaccharide, the smoke of cigarette was mild and glomerate, polysaccharides offered enhanced sweety aroma, as well as the aroma quantity, improve after-tasting and reduce offensive taste and irritation of cigarette. The optimum application amount was(5~10)×10-6 g. The pyrolysis of polysaccharide could release micromolecule aldehydes and ketones containing special odor having floral, toast, sweet, milk and fruity notes.
In order to study the pyrolysis behavior of Lycium barbarum L. polysaccharide and influence on the cigarette sensory quality,the polysaccharide was extracted by water extraction and alcohol precipitation method. The pyrolysates were analyzed in different atmosphere(10% O2 and 90% N2) and at temperature levels(300℃,600℃, 750℃ and 900℃). The pyrolysates were directly introduced into Py-GC-MS spectrometer, quantitative analysis was made by area normalization. The results showed that cigarette sensory quality was improved by polysaccharide, the smoke of cigarette was mild and glomerate, polysaccharides offered enhanced sweety aroma, as well as the aroma quantity, improve after-tasting and reduce offensive taste and irritation of cigarette. The optimum application amount was(5~10)×10-6 g. The pyrolysis of polysaccharide could release micromolecule aldehydes and ketones containing special odor having floral, toast, sweet, milk and fruity notes.
2015, 30(2)
:42-47,59.
doi: 10.3969/j.issn.2095-476X.2015.02.010
Abstract:
The effects of processing parameters of vacuum conditioning,tobacco leaf storage,cutting,and cut tobacco roller drying processing on tobacco leaf cut tobacco product's color and lustre were studied using color difference instrument. The results showed that tobacco leaf brightness and color processed by two cycle vacuum conditioning more decreased than one, and tobacco leaf brightness and color also more decreased when conditioning temperature increased,time of keeping temperature and time of vacuum pumping longer in one cycle vacuum conditioning. Tobacco leaf brightness and color decreased more,color increases,color and lustre worse when temperature and humidity of storage environment increased and time of storage became longer. Cut tobacco brightness and color decreased more,color increased,color and lustre were worse when moisture content of tobacco and cutter mouthpiece pressure increased. The color had little influence on cut tobacco roller drying. According to the experiments results,the preferable process conditions were determined to keep excellent color and lustre of tobacco leaf and cut tobacco,which were one cycle vacuum conditioning,lighter processed strength(conditioning temperature was less than or equal to 55℃,time of keeping temperature and vacuum pumping were less than or equal to 50 s and 70 s); tem-perature and humidity of storage environment were 26℃ and 63% respectively,time of leaf storage was 2~8 h; moisture content of cutting was below 18.5%, and cutter mouthpiece pressure was below 0.2 MPa,the hot air temperature was 105℃ and the temperature of the tube wall of roller was 125℃.
The effects of processing parameters of vacuum conditioning,tobacco leaf storage,cutting,and cut tobacco roller drying processing on tobacco leaf cut tobacco product's color and lustre were studied using color difference instrument. The results showed that tobacco leaf brightness and color processed by two cycle vacuum conditioning more decreased than one, and tobacco leaf brightness and color also more decreased when conditioning temperature increased,time of keeping temperature and time of vacuum pumping longer in one cycle vacuum conditioning. Tobacco leaf brightness and color decreased more,color increases,color and lustre worse when temperature and humidity of storage environment increased and time of storage became longer. Cut tobacco brightness and color decreased more,color increased,color and lustre were worse when moisture content of tobacco and cutter mouthpiece pressure increased. The color had little influence on cut tobacco roller drying. According to the experiments results,the preferable process conditions were determined to keep excellent color and lustre of tobacco leaf and cut tobacco,which were one cycle vacuum conditioning,lighter processed strength(conditioning temperature was less than or equal to 55℃,time of keeping temperature and vacuum pumping were less than or equal to 50 s and 70 s); tem-perature and humidity of storage environment were 26℃ and 63% respectively,time of leaf storage was 2~8 h; moisture content of cutting was below 18.5%, and cutter mouthpiece pressure was below 0.2 MPa,the hot air temperature was 105℃ and the temperature of the tube wall of roller was 125℃.
2015, 30(2)
:48-51.
doi: 10.3969/j.issn.2095-476X.2015.02.011
Abstract:
Process parameters of tobacco stem pretreatment were optimized by using the methods of single factor experiment and orthogonal experiment,the influence trend of the stability of the standard deviation of the water content of tabacco stem was analyzed. The results showed that when the washing time was 60 s, washing water temperature was 60℃, storage time was 3 h and steamed terrier outlet temperature was 80℃,the tobacco stem return penetration rate was 99.3%.
Process parameters of tobacco stem pretreatment were optimized by using the methods of single factor experiment and orthogonal experiment,the influence trend of the stability of the standard deviation of the water content of tabacco stem was analyzed. The results showed that when the washing time was 60 s, washing water temperature was 60℃, storage time was 3 h and steamed terrier outlet temperature was 80℃,the tobacco stem return penetration rate was 99.3%.
2015, 30(2)
:52-55.
doi: 10.3969/j.issn.2095-476X.2015.02.012
Abstract:
Based on the mechanism of RFID system and limitation of low-cost tags which storage capacity and computing ability,a new RFID tag ownership transfer protocol was presented. In communication process of protocol,lightweight operations were adopted,tag anonym was transmitted in wireless channel which was processed by Pseudo-random Encryption Function. Shared-key recovery mechanism was used to excute authentication and authorization between tags and owners,which could ensure the robusthess of the protocol. At the same time,the shared-key dynamically negotiated and updated by both communication sides. It improved the security of information data in the process of ownership transfer. The analysis results compared with other protocols showed that the protocol could resist various attacks by low-complexity algorithms,and had lower traffic and higher computation efficiency.
Based on the mechanism of RFID system and limitation of low-cost tags which storage capacity and computing ability,a new RFID tag ownership transfer protocol was presented. In communication process of protocol,lightweight operations were adopted,tag anonym was transmitted in wireless channel which was processed by Pseudo-random Encryption Function. Shared-key recovery mechanism was used to excute authentication and authorization between tags and owners,which could ensure the robusthess of the protocol. At the same time,the shared-key dynamically negotiated and updated by both communication sides. It improved the security of information data in the process of ownership transfer. The analysis results compared with other protocols showed that the protocol could resist various attacks by low-complexity algorithms,and had lower traffic and higher computation efficiency.
2015, 30(2)
:56-59.
doi: 10.3969/j.issn.2095-476X.2015.02.013
Abstract:
Aiming at the problem of interactive pickup of terrain point's accurate coordinate, the pickup strategy of terrain point coordinate based on geometric method was proposed. The strategy used the intersecting geometric ray and sphere, and designed the dichotomy of spherical center's angle which searched the accurate terrain point's coordinate according to DEM spatial information. The experimental results showed that the strategy not only got the accurate coordinates of the intersection of terrain,but also increasesd interactive operating fluency in virtual reality geographic system,and it provided a new approach for studying the theory of generating interactively curve on Earth.
Aiming at the problem of interactive pickup of terrain point's accurate coordinate, the pickup strategy of terrain point coordinate based on geometric method was proposed. The strategy used the intersecting geometric ray and sphere, and designed the dichotomy of spherical center's angle which searched the accurate terrain point's coordinate according to DEM spatial information. The experimental results showed that the strategy not only got the accurate coordinates of the intersection of terrain,but also increasesd interactive operating fluency in virtual reality geographic system,and it provided a new approach for studying the theory of generating interactively curve on Earth.
2015, 30(2)
:60-66.
doi: 10.3969/j.issn.2095-476X.2015.02.014
Abstract:
An improved priority backoff algorithm was proposed based on the P_BEB algorithm. The algorithm determined the contention window value by the probability g, and then executed the send action. If the data frames sent failure, the competition window value was set double according to the time slot utilization rate, with probability g settings window value after the success of the send,namely according to the adjustment of the current value of the contention window. The optimized algorithm was verified using the Infrastructure scene, the results showed that this method effectively improved the throughput, and could maintain the small access delay, reduce packet loss amount of system,and improve the performance of wireless local area network.
An improved priority backoff algorithm was proposed based on the P_BEB algorithm. The algorithm determined the contention window value by the probability g, and then executed the send action. If the data frames sent failure, the competition window value was set double according to the time slot utilization rate, with probability g settings window value after the success of the send,namely according to the adjustment of the current value of the contention window. The optimized algorithm was verified using the Infrastructure scene, the results showed that this method effectively improved the throughput, and could maintain the small access delay, reduce packet loss amount of system,and improve the performance of wireless local area network.
2015, 30(2)
:67-71.
doi: 10.3969/j.issn.2095-476X.2015.02.015
Abstract:
The physical models from the supermarket scale, open vertical refrigerated display cabinet to the shelf scale were built based on the system multiscale method, and the fluid flow and heat transfer character of three different scales were analyzed. The computational results showed the temperature and velocity fields had very good agreement among three scales. The average deviations of temperature and air velocity for the second shelf were 1.31℃ and 0.2 m/s, respectively. The multiscale method of the proposed system could correctly predict the temperature and velocity distribution from the supermarket space to inside of refrigerated display cabinet.
The physical models from the supermarket scale, open vertical refrigerated display cabinet to the shelf scale were built based on the system multiscale method, and the fluid flow and heat transfer character of three different scales were analyzed. The computational results showed the temperature and velocity fields had very good agreement among three scales. The average deviations of temperature and air velocity for the second shelf were 1.31℃ and 0.2 m/s, respectively. The multiscale method of the proposed system could correctly predict the temperature and velocity distribution from the supermarket space to inside of refrigerated display cabinet.
2015, 30(2)
:72-76,92.
doi: 10.3969/j.issn.2095-476X.2015.02.016
Abstract:
In the present study, the heat transfer and fluid flow characteristics of fin-tube heat exchangers of circular-tube, equal-diameter elliptic-tube and equal-perimeter elliptic-tube with delta winglets longitudinal vortex was presented based on the numerical simulation. The result showed that the temperature and velocity field of equal-perimeter elliptic-tube fin heat exchanger more uniform, and its heat transfer performance was the best, and the Nu number of equal-diameter elliptic-tube fin heat exchanger was the largest,which was 2.2%~6.1% higher than that of circular-tube heat exchanger with delta winglets, 6.5%~8.3% higher than that of equal-radius elliptic-tube heat exchanger and with delta winglets and 29.1%~33.5% higher than that of flat fin-tube heat exchanger. Considering from the overall performance, the delta winglets longitudinal vortex oval fin-tube heat exchanger fit for moderate and high Reynolds numbers.
In the present study, the heat transfer and fluid flow characteristics of fin-tube heat exchangers of circular-tube, equal-diameter elliptic-tube and equal-perimeter elliptic-tube with delta winglets longitudinal vortex was presented based on the numerical simulation. The result showed that the temperature and velocity field of equal-perimeter elliptic-tube fin heat exchanger more uniform, and its heat transfer performance was the best, and the Nu number of equal-diameter elliptic-tube fin heat exchanger was the largest,which was 2.2%~6.1% higher than that of circular-tube heat exchanger with delta winglets, 6.5%~8.3% higher than that of equal-radius elliptic-tube heat exchanger and with delta winglets and 29.1%~33.5% higher than that of flat fin-tube heat exchanger. Considering from the overall performance, the delta winglets longitudinal vortex oval fin-tube heat exchanger fit for moderate and high Reynolds numbers.
2015, 30(2)
:77-82.
doi: 10.3969/j.issn.2095-476X.2015.02.017
Abstract:
Brushless DC motor(BLDCM) has the problem of torque ripple due to its structural characteristics and traditional modulation mode,which limits its application range and especially in high precision servo system. A control method that combines the PWM-ON-PWM modulation mode with BUCK converter basis on position sensorless was proposed, to eliminate or suppress the torque ripple. Simulink results showed that the method can not noly completely eliminate the freewheel current of silent phase to eliminate the non-commutation torque ripple, but also decrease the commutation torque ripple in the running process of the motor.
Brushless DC motor(BLDCM) has the problem of torque ripple due to its structural characteristics and traditional modulation mode,which limits its application range and especially in high precision servo system. A control method that combines the PWM-ON-PWM modulation mode with BUCK converter basis on position sensorless was proposed, to eliminate or suppress the torque ripple. Simulink results showed that the method can not noly completely eliminate the freewheel current of silent phase to eliminate the non-commutation torque ripple, but also decrease the commutation torque ripple in the running process of the motor.
2015, 30(2)
:83-87.
doi: 10.3969/j.issn.2095-476X.2015.02.018
Abstract:
According to power performance requirements of independent designed micro-electric vehicle with four-wheel-independent drive,the matching design of drive motor power,the capacity and number of battry was performancd. By using software AVLCruise,a simulation analysis on its power performance was conducted. The parameters were used in the design of electrical system and component parameter selection. Finally by real vehicle test,the result showed that the relation parameters of powertrain system met design requirements,the drive current graph of trunk circuits in different driving modes was suitable.
According to power performance requirements of independent designed micro-electric vehicle with four-wheel-independent drive,the matching design of drive motor power,the capacity and number of battry was performancd. By using software AVLCruise,a simulation analysis on its power performance was conducted. The parameters were used in the design of electrical system and component parameter selection. Finally by real vehicle test,the result showed that the relation parameters of powertrain system met design requirements,the drive current graph of trunk circuits in different driving modes was suitable.
2015, 30(2)
:88-92.
doi: 10.3969/j.issn.2095-476X.2015.02.019
Abstract:
Aiming at how to accurately determine the short circuit fault in power system in order to improve the reliability and sensitivity of the relay protection of power system, a method which used short-circuit current in a non-periodic component as a criterion in short-circuit fault was proposed. Using Matlab to extract short-circuit current of the non-periodic component,was then applied the features of the non-periodic component in the short circuit current to the relay protection of power system. The test run results showed that the directional differential protection of non-periodic components was not affected by the influence of line to ground capacitance. Either as a sole major protection, or as a part of the combined protections, it can always accurately identify the short fault of electric system. However, non-periodic components are transient signals with short existence, therefore a signal maintainer is needed during operation.
Aiming at how to accurately determine the short circuit fault in power system in order to improve the reliability and sensitivity of the relay protection of power system, a method which used short-circuit current in a non-periodic component as a criterion in short-circuit fault was proposed. Using Matlab to extract short-circuit current of the non-periodic component,was then applied the features of the non-periodic component in the short circuit current to the relay protection of power system. The test run results showed that the directional differential protection of non-periodic components was not affected by the influence of line to ground capacitance. Either as a sole major protection, or as a part of the combined protections, it can always accurately identify the short fault of electric system. However, non-periodic components are transient signals with short existence, therefore a signal maintainer is needed during operation.
2015, 30(2)
:93-98.
doi: 10.3969/j.issn.2095-476X.2015.02.020
Abstract:
According to station missing phenomenon of EM277(communication interruption) in the Profibus DP network system running process,based on the built Profibus network experiment platform,working environment factors such as the electromagnetic interference(EMI), grounding system,the settings of network parameter and so on were simulated,and combined with Profibus network message analysis,the phenomenon of EM277 station missing was analyzed. The corresponding engineering solution was proposed: reasonably setting up network system parameters,adding repeaters to realized the effective amplification and regeneration treatment,shielding and correcting grounding of network equipment and communication cables to inhibit EMI. etc. The feasibility of the scheme was verified by engineering examples.
According to station missing phenomenon of EM277(communication interruption) in the Profibus DP network system running process,based on the built Profibus network experiment platform,working environment factors such as the electromagnetic interference(EMI), grounding system,the settings of network parameter and so on were simulated,and combined with Profibus network message analysis,the phenomenon of EM277 station missing was analyzed. The corresponding engineering solution was proposed: reasonably setting up network system parameters,adding repeaters to realized the effective amplification and regeneration treatment,shielding and correcting grounding of network equipment and communication cables to inhibit EMI. etc. The feasibility of the scheme was verified by engineering examples.
2015, 30(2)
:99-101.
doi: 10.3969/j.issn.2095-476X.2015.02.021
Abstract:
The real estate investment system was built to the complex networks chaos system and the chaos H∞ synchronization of this network model was studied. The sufficient conditions for achieving the H∞ synchronization and synchronization of the system were derived based on Lyapunov stability theory and self-adaptive control approach.
The real estate investment system was built to the complex networks chaos system and the chaos H∞ synchronization of this network model was studied. The sufficient conditions for achieving the H∞ synchronization and synchronization of the system were derived based on Lyapunov stability theory and self-adaptive control approach.
2015, 30(2)
:102-104.
doi: 10.3969/j.issn.2095-476X.2015.02.022
Abstract:
Under the stochastic interest rate, the insurance policies and investment returns were bivariate discrete risk model with random variables, stochastic investment yields under the double binomial risk model, and the general formula was gottenfor the ruin probability Ψ(u) when the initial reserve was u=U(0) in certain special circumstances which not only strengthened the reality description ability of the model, and had more practical meaning to promote stable operation of the insurance company, the insurance company insolvency probability study.
Under the stochastic interest rate, the insurance policies and investment returns were bivariate discrete risk model with random variables, stochastic investment yields under the double binomial risk model, and the general formula was gottenfor the ruin probability Ψ(u) when the initial reserve was u=U(0) in certain special circumstances which not only strengthened the reality description ability of the model, and had more practical meaning to promote stable operation of the insurance company, the insurance company insolvency probability study.
2015, 30(2)
:105-108.
doi: 10.3969/j.issn.2095-476X.2015.02.023
Abstract:
Aiming at the price of pork influenced by many factors,and the difficulty to use fixed mathematical model to predict them accurately, an improved GM(1,1) model was presented. This model used improved background value and M accumulating generation operator(AGO) method residual correction, took the changes of pork's price as a gray system,and used dimensions additional methods to predict the development trend of the price. The prediction accuracy was better. Taking the pork price in Jilin Province as an example,using improved GM(1,1) model to forecast the future price of pork had practical significance for improving the producer income and promoting benign development of pork market.
Aiming at the price of pork influenced by many factors,and the difficulty to use fixed mathematical model to predict them accurately, an improved GM(1,1) model was presented. This model used improved background value and M accumulating generation operator(AGO) method residual correction, took the changes of pork's price as a gray system,and used dimensions additional methods to predict the development trend of the price. The prediction accuracy was better. Taking the pork price in Jilin Province as an example,using improved GM(1,1) model to forecast the future price of pork had practical significance for improving the producer income and promoting benign development of pork market.
Journal Information
Founded in 1986， bimonthly
Administered by：The Education Department Henan Province
Sponsored by：Zhengzhou University of Light Industry
Editor-in-chief：Wei Shizhong
Executive Editor-in-Chief：Zou Lin
Subeditor：Qu Shuanghong
Edited & published by：Editorial Department of Journal of Light Industry
CN 41-1437/TS
ISSN 2096-1553
Address：136 Science Avenue, Zhengzhou City, Henan Province, China
Postal Code：450001
Tel：(086)0371-86608635
(086)0371-86608633
