Volume 37,Issue 8,2014 Table of Contents

1 Review of research on international gear transmissions

QIN Datong

2014, 37(8):1-10. DOI: 10.11835/j.issn.1000-582X.2014.08.001

[Abstract](2151) [HTML](532) [PDF 6.82 M](2089)

Abstract:
Several international conferences on gears is introduced, furthermore, the statistic analysis is conducted on the international gear research in recent years by taking example of the most influential Germany international gear conference. Some important issues on the design, manufacture, and application of gear transmissions is discussed including how to improve the load capacity, suppress vibration and noise, improve transmission efficiency, save resources, improve the efficiency of manufacture, and avoid the environmental contamination, and so on. Main progresses and research highlights of the international gear researches are also introduced and analyzed.

2 Compaction mechanism oriented axis structure and size design and finite element method checking

WANG Shilong , WANG Xia , ZHOU Jie , ZHAO Yu , LIU Jiansong , SUN Shouli

2014, 37(8):11-18. DOI: 10.11835/j.issn.1000-582X.2014.08.002

[Abstract](1466) [HTML](480) [PDF 8.87 M](1175)

Abstract:
To solve the compaction mechanism problems such as insufficient steering shaft strength stiffness caused by partial load， the force method and the displacement method in structural mechanics are used in compaction mechanismguide shaft structure size design， and the design parameters and the formula of the statically indeterminate structure under symmetrical loading arededuced.The designed compaction mechanism oriented axis is analyzed in three-dimensional contact finite element analysis by using finite element analysis software Abaqus. Stress and deformation under full load conditions are studied. Results show that the guide shaft deformation is smallwhen the compaction mechanism in full load conditionand the stress on the guide shaft in all directions are less than the allowable stress.Research methods and results will provide guidance for designing the compaction mechanism guide shaft.

3 Development of control system for a CNG/gasoline bi-fuel engine

GE Xiaocheng , XU Zhongming , LI Jingbo , ZOU Bowen

2014, 37(8):19-24. DOI: 10.11835/j.issn.1000-582X.2014.08.003

[Abstract](1598) [HTML](485) [PDF 6.94 M](1157)

Abstract:
The CNG/gasoline bi-fuel vehicle using CNG as the primary fuel and gasoline as a secondary has good economy and emission performance，but the traditional bi-fuel engine uses master/slave dual ECU system cannot realize it. For improving the performance，the research with multi-point sequential injection based on single ECU which is designed for OEM is made. The CNG special control strategies are designed such as Lambda PI control logic of Non-symmetric oscillation，and also the experimental investigation for this bi-fuel engine and the emission test of vehicle are carried out. According to the experiment results，the performance of engine with single ECU is better than the engine with master/slave dual ECU，and the value of emission is less than euro IV emission levels when we use CNG fuel.

4 Grinding teeth temperature analysis of large flat wheel

LI Guolong , PENG Yuanzhi , HE Kun , LIU Xiaoxu

2014, 37(8):25-33. DOI: 10.11835/j.issn.1000-582X.2014.08.004

[Abstract](1989) [HTML](3278) [PDF 10.61 M](6988)

Abstract:
At present，there are many planar workpiece grinding thermal models. However，they cannot be applied to the calculation of the tooth-like surface grinding. Therefore，based on the gear involute arc fitting，the moving heat source method and the imaging method are combined in this work to deduce the analytical thermal model of grinding teeth with large flat wheel，which can be used to calculate the temperature of grinding gears. The simulation of grinding process is made based on ANSYS and compare to the established quasi-steady-state analytical thermal model. The comparison results show that the value of grinding temperature predicted by numerical model has well agreement with the analytical model and some errors exist in the contact area and the junction between contact area and non-contact area. The deduced analytical thermal model can be used to analyze the temperature of processing tooth-like curve workpiece.

5 Discriminate ferroresonance from single-phase earth fault in sine fitting algorithm

JIANG Jie , ZHAO Guangquan , ZHANG Xiao , SHAN Yuqing , GUO Wei

2014, 37(8):34-40. DOI: 10.11835/j.issn.1000-582X.2014.08.005

[Abstract](1317) [HTML](759) [PDF 6.77 M](1083)

Abstract:
The potential transformer ferroresonance often occurs in neutral non-grounding distribution network，which cause zero sequence voltage rise. The phenomenon is similar to single-phase earth fault，and it may result in maloperation of line-selecting earthing devices. A new method is presented for discriminating between ferroresonance and single-phase earth fault. First，sampled data of zero-sequence voltage is fitted to sine function of 50 Hz，and it can get that the zero sequence voltage is power frequency or not by analyzing the amplitude. Second，to the case that zero-sequence voltage is power frequency，the fundamental frequency resonance can be correctly identified from single-phase earth fault by calculating waveform distortion level as zero-sequence voltage is distorted if fundamental frequency resonance occurred. Simulation data show that the method can discriminate single-phase earth and ferromagnetic resonance effectively.

6 Thermal aging behavior of XLPE cable based on the nuclear magnetic resonance theory

DENG Wendong , YUAN Fanning , LI Jun , CHEN Yiyuan

2014, 37(8):41-45. DOI: 10.11835/j.issn.1000-582X.2014.08.006

[Abstract](1429) [HTML](466) [PDF 5.35 M](1171)

Abstract:
XLPE cable in practical application is subjected mostly to thermal stress， which would cause an irreversible damaging and shorten its lifetime. A method based on nuclear magnetic resonance (NMR)is proposed. This paper presents the characteristic quantities of thermal aging process-vertical relaxation time and area of wave crest. Experimental results indicate that the vertical relaxation time and area of wave crest decreases with the increase of aging time and aging temperature， and the relationship between the area of wave crest and aging time is approximately linear. The proposed method provides great application value for monitoring cable aging process.

7 Analysis on the lengths of spill flame under a horizontal projection at the building faade

YANG Dong ab , ZHAO Cong , GUO Yuanhao , JIANG Yaqiang

2014, 37(8):46-52. DOI: 10.11835/j.issn.1000-582X.2014.08.007

[Abstract](1736) [HTML](377) [PDF 7.05 M](1196)

Abstract:
The effects of heat release rate and opening size on the structure of spill flame beneath a horizontal projection are investigated. The lengths of the spill flame are obtained from digital videos combined with an image processing method. The theoretical model that describes the flow and combustion dynamics of spill flame under a horizontal projection is established. The air entrainment coefficient and the excess air ratio are determined by combing the theoretical model and the measured temperatures，which are about 0.12 and 3.7，respectively. The prediction formula for the flame length under a horizontal projection is thus obtained，which provides references for the passive fire prevention design by using horizontal projections.

8 Applicability analysis of ice slurry as secondary refrigerant in multi-subway station central cooling system in distinct climatic zones

ZHANG Xu , WANG Qun

2014, 37(8):53-58. DOI: 10.11835/j.issn.1000-582X.2014.08.008

[Abstract](1382) [HTML](390) [PDF 6.27 M](1198)

Abstract:
Based on the latest research results about ice slurry on HVAC，this paper analyzes the annual cost of secondary piping network of ice slurry & ice storage central cooling system. Fitting the function of secondary pipe network annual cost per unit length and analyzing the applicability of ice slurry central cooling system. The results show that adopting ice slurry central cooling system in Guangzhou will effectively reduce the secondary piping network investment and the advantage of ice slurry central cooling system will increase with the extension of cooling period，cooling load and the length of secondary piping network.

9 Sensitivity analysis of influencing factors for dynamic characteristics of lacustrine soft soil

TANG Jia , DENG Zongwei , GAO Qianfeng , JIANG Jianqing

2014, 37(8):59-66. DOI: 10.11835/j.issn.1000-582X.2014.08.009

[Abstract](1339) [HTML](326) [PDF 8.30 M](1164)

Abstract:
Three factors，i.e. dynamic stress amplitude，vibration frequency and confining pressure，are considered for the orthogonal test design of 3 factors and 3 levels. And according to the orthogonal design，dynamic triaxial tests are carried out to study the axial accumulated strain，dynamic pore water pressure and dynamic elastic modulus of lacustrine soft soil under cyclic loads. Then the sensitivity analysis method is employed to research the sensitivity of each dynamic characteristic index influenced by various loading factors. Results show that the dynamic stress amplitude is the most significant impact factor to the axial accumulated strain，dynamic pore water pressure and dynamic elastic modulus. Confining pressure is the secondary factor affecting the axial accumulated strain and dynamic elastic modulus，and vibration frequency is the secondary factor influencing the dynamic pore water pressure.

10 Constitutive relation and failure criterion for X60 pipeline steel

MA Tingxia , YANG Yonghe , XU Zhen , LI Anjun , TANG Yu

2014, 37(8):67-75. DOI: 10.11835/j.issn.1000-582X.2014.08.010

[Abstract](1758) [HTML](880) [PDF 8.50 M](1289)

Abstract:
The X60 pipeline steel is the steel which is most commonly applied to the transportation of oil and natural gas，but under the external load，deformation or stress concentration is more likely to occur on the X60 pipeline steel，and thus it results to buckling even cracking failure. For studying the mechanical behavior of the X60 pipeline steel，evaluating its mechanical safety has become one of the most important works for the pipeline risk management. Among all the works of risk management，the constitutive relation equation is the basis of the whole mechanics research，and the failure criterion determines the pipeline’s life cycle. By comparing the static tensile stress-strain relationship and the Ramberg-Osgood constitutive relation of X60 pipeline steel，we find when ε≤εP0.2，the Ramberg-Osgood constitutive equation can more accurately reflect the X60 pipeline steel’s tensile stress-strain relationship；however，when ε＞εP0.2，the theoretical constitutive curve，which is based on the experimental results of Ramberg-Osgood constitutive model，has larger deviation. Based on this observation and according to the different mechanical characteristics during the static tensile elastic stage and plastic stage，we make a revision on the Osgood constitutive model by using the interpolation method and propose the X60 pipeline steel’s global 2-phase stress strain relation under the condition of unidirectional pull-up，which can represent the X60 pipeline steel’s tensile stress-strain relationship more accurately. Considering the effects caused by the weld seam and heat-affected zone to the pipeline strength and stiffness，and combined with the failure criterion based on the stress and strain about plastic material，this article proposes the influence factor and the failure criterion of the strain control for the X60 pipeline steel，also establishes critical stress calculation equation based on the fourth strength theory at the time of pline failure.

11 Analysis on electrically controlled tunable dual-band metamaterials absorber

WANG Liansheng , XIA Dongyan , LYU Zhensu , FU Quanhong

2014, 37(8):76-82. DOI: 10.11835/j.issn.1000-582X.2014.08.011

[Abstract](1510) [HTML](538) [PDF 8.44 M](1160)

Abstract:
In order to realize the absorption frequency controlling of metamaterials absorber intelligently，a dual-band metamaterials absorber is designed in this paper firstly，and then the electrorheological fluid is loaded in the dual-band metamaterials absorber，and the absorption frequency of dual-band metamaterials absorber is tunable by changing the electric field strength applied on electrorheological fluid. The results show that the designed metamaterials absorber has two absorption peaks at 7.403 GHz and 17.511 GHz，and the absorption rate is 99.8% and 70% respectively. With the increase of electric field strength，the absorption frequency gradually moves towards lower frequency，and the absorption frequency regulation rate is up to 55%. Therefore，we propose the concept of dual-band intelligent metamaterials absorber.

12 Influence analysis of dry ice cleaning to the concrete surface pore

REN Song , SHI Yanhua , JIANG Deyi , CHEN Jie

2014, 37(8):83-90. DOI: 10.11835/j.issn.1000-582X.2014.08.012

[Abstract](1694) [HTML](485) [PDF 7.51 M](1380)

Abstract:
The result of concrete dry ice cleaning test with KBQX-30DG，which is a single tube dry ice cleaning machine，shows cleaning effect is good，but can make pore on the concrete surface. Based on the orthogonal experiment design method，study the four factors of dry ice flow，cleaning distance，cleaning time and injection angle in the process of dry ice cleaning how to affect the surface porosity growth. The range analysis results show that the most important factor to the surface porosity growth is dry ice flow. With the dry ice flow increase，the surface porosity growth increased，and the surface porosity growth will leap when the dry ice flow is greater than 1.54 kg/min；the injection angle has obvious influence on the surface porosity growth，when injection angle is in the scope of 55°~60°and 85°~90°，and the amount of pore is more than these in the scope of 65°~70°and 75°~80°；the influence on the surface porosity growth of cleaning distance and cleaning time is not obvious. By linear regression analysis and AHP we can obtain the weights on the surface porosity growth of four factors’ through which we can get the primary and secondary order of each factor，and the result is consistent with the range analysis.

13 Analysis of distribution characteristics of surface ozone and its influencing factors in summer in Chongqing

LIU Jiaojiao , JIANG Changtan , SONG Dan , AN Beibei

2014, 37(8):91-98. DOI: 10.11835/j.issn.1000-582X.2014.08.013

[Abstract](1964) [HTML](3344) [PDF 10.05 M](6993)

Abstract:
Based on the observation data of ozone and its precursor compounds and meteorological factors in near surface layer of Chongqing urban area，this paper emphatically analyzes the temporal and spatial distribution characteristics of ozone in summer. Meanwhile，the correlation between ozone and its precursor compounds，such as NO，NO2，CO，and some related meteorological factors are analyzed. Results show that the concentration of ozone in urban area is lower than that in the surrounding regions. Only one peak of ozone concentration appeared in about 4 p.m. The ozone concentration has an obvious negative correlation with precursor compounds，and has obvious positive correlation with meteorological factors，such as solar radiation and temperature. The appearance of high ozone concentrations resulted from the high pressure weather conditions，especially for the high intensity of solar radiation，breeze，low relative humidity and high temperature. Elevated ozone concentration is closely related to the decrease amplitude of atmospheric pressure. Higher ozone concentrations appear when the decrease amplitude is 0.4 kPa.

14 Optimization of in-pit haulage system development during internal dumping in seasonal stripping surface coal mine

BAI Runcai , LIU Chuang , LIU Guangwei , CAO Bo

2014, 37(8):99-104. DOI: 10.11835/j.issn.1000-582X.2014.08.014

[Abstract](1487) [HTML](349) [PDF 6.72 M](1263)

Abstract:
For the features of long haul distances and high motor transport haulage cost during internal dumping in near horizontal surface coal mine with seasonal stripping，on the basis of theoretical calculation and analysis，the paper proposes a thought that building temporary connection bridges to optimize in-pit haulage system development. And an techno-economic analysis about form and building requirements of temporary connection bridges is made，the parameters model and optimization algorithm of temporary connection bridges are provided. The research production has been practical applied to West 2 surface coal mine of Mengdong energy holdings co.，LTD. The results show that building temporary connection bridges to optimize in-pit haulage system development generates remarkable economical benefits.

15 An image segmentation method based on Chan-Vese model combined with threshold algorithm

TANG Zhide , TIAN Bin

2014, 37(8):105-110. DOI: 10.11835/j.issn.1000-582X.2014.08.015

[Abstract](1399) [HTML](852) [PDF 6.83 M](1070)

Abstract:
Threshold segmentation is a basic grey-scale converting technology of image processing. We combine threshold segmentation with Chan-Vese model with an accompanying scale transformation to improve the segment speed and effect. Experimental results show that this program greatly enhances the convergent speed of the Chan-Vese model，and it focuses on changing the defects of more iterative times and low diffusion speed of Chan-Vese model on the border of the image when its grayscale changes slowly.

16 To maintain maximum throughput IEEE 802.11 DCF protocol power control mechanism

ZHANG Hairong , GUO Songtao , CHEN Piao

2014, 37(8):111-118. DOI: 10.11835/j.issn.1000-582X.2014.08.016

[Abstract](1634) [HTML](941) [PDF 8.39 M](1301)

Abstract:
Transmission power control has been extensively used not only to save energy，but also to improve the network throughput in wireless ad hoc networks. A new adaptive power control algorithm，i.e.，PCMAC algorithm，based on IEEE 802.11 DCF protocol for Vehicular Ad hoc networks is proposed. According to the communication status，the algorithm dynamically adjusts the transmit powers of the CTS frames of receiving nodes and the data packets of the transmitting nodes，furthermore，adjusts the transmit powers of the RTS frames of the transmitting nodes according to the optimal number of access nodes such that the network throughput is maximized，in order to avoid conflicts and increase throughput. The simulation results show that the proposed PCMAC (power control media access control)algorithm can not only decrease the average energy consumption so as to prolong the lifetime of the network，but also improve spatial reuse of the wireless channel so as to improve the average throughput of the network.

17 A TTL limited scheme to reduce PREQs broadcast storm

YOU Bo , MU Rongzeng , YAN Yuepeng

2014, 37(8):119-126. DOI: 10.11835/j.issn.1000-582X.2014.08.017

[Abstract](1727) [HTML](430) [PDF 7.63 M](1406)

Abstract:
In the tree network of IEEE802.11s using HWMP (hybrid wireless mesh protocol)as its routing protocol，PREQs (path requests)are simply flooded for maintaining the routes between leaf nodes，which causes PREQs broadcast storm problem. This paper proposes a TTL limited scheme to solve the problem. The scheme designs a method to grade the leaf nodes. With the help of table-driven routing in HWMP，the leaf nodes are divided into different grades according to their hop counts to the root node and the grade information is synchronized in the network. The source node no longer uses the default TTL in HWMP when sending PREQ，instead，it sets the TTL of the PREQ to the sum of its own grade and the destination node’s grade. Theoretical analysis and experimental results show that the scheme limits the delivery distance of PREQs and outperforms HWMP at overhead，loop delay，package loss rate and throughput in static tree network if the sum of the source node’s grade and the destination node’s grade is not large.

18 Design of anultra-wideband monopole antenna with dual band-notched function

LYU Hong , XIA Xinsheng , WU Dongsheng , PING Lanlan , YU Yonglin

2014, 37(8):127-131. DOI: 10.11835/j.issn.1000-582X.2014.08.018

[Abstract](1497) [HTML](924) [PDF 6.40 M](1206)

Abstract:
In wireless communication systems，in order to overcome the mutual interference among systems，an UWB monopole antenna with dual band-notched characteristic is proposed using band-suppressed technology. Using the techniques of loading and slotting makes the returned loss of the antenna less than -10 dB in the band of 2.6~14.6 GHz. Through slotting on the ground plane and the radiating patch，VSWR is greater than 2 in the range of IEEE802.16 of 3.3~3.6 GHz，C-wave satellite communications system 3.7~4.2 GHz，and IEEE802.11a of 5.15~5.825 GHz frequency band. Results of simulation and test show that the antenna has good function of suppression，simple structure and small size.

19 Research on stable points of cellular neural networks with high gain activation function

WANG Ping , HAN Qi

2014, 37(8):132-137. DOI: 10.11835/j.issn.1000-582X.2014.08.019

[Abstract](1661) [HTML](335) [PDF 5.99 M](1261)

Abstract:
Equilibrium points of cellular neural networks (CNNs)provide theoretical support for associative memories. However，the CNNs with high gain activation function have not been studied. Unity gain function is included by high gain activation function. Therefore，there are wide applications for high gain activation function. In this paper，the number of equilibrium points of each cell in CNNs with high gain activation function is considered. Some stable conditions about CNNs are obtained by use of the relationship between connection parameters. From these stable conditions and inputs and outputs of a CNN，the regions of values of parameters in CNNs can be gotten. Meanwhile，the number of equilibrium points of every cell can be obtained，where the number is less than 2 δ. Some numerical simulations are presented to support the effectiveness of the theoretical analysis.

20 Research on immunization strategies based on independent sets of complex networks

HUANG Bin , ZHAO Xiangyu , WU Chunwang

2014, 37(8):138-143. DOI: 10.11835/j.issn.1000-582X.2014.08.020

[Abstract](1581) [HTML](494) [PDF 5.88 M](1131)

Abstract:
According to the concept of independent set, this paper proposes a new immunization strategy of complex networks which immunizes the nodes in an independent set with maximum degree, called targeted immunization in the independent set. When the total degree of immune nodes in independent set is equal to the total degree of targeted immunization nodes in the whole network, the immunization strategy of independent set is more effective than the targeted immunization strategy of the whole network. Based on the network structure, this paper explains the reason. Comparing the random immunization of independent sets with the random immunization in the whole network, test results indicate that more nodes do not be removed with high degree for the random immunization of independent sets. For classic susceptible-infected(SI) model, all nodes in the network are only two states: susceptible or infected. In the study of immunization strategies, comparing SI model with SIR, SIS models. The use of SI model will be more favorable.

21 WSN localization algorithm based on RSSI correction

WU Shilong , ZHANG Wanli , YANG Xiaoying

2014, 37(8):144-150. DOI: 10.11835/j.issn.1000-582X.2014.08.021

[Abstract](1700) [HTML](368) [PDF 8.09 M](1037)

Abstract:
In order to solve the problem that there is large errors in DV-Hop algorithm in network topology environments, a modified RSSI-based WSN localization algorithm RMDV-Hop (RSSI Modify DV-Hop)is presented in this paper. The algorithm limits the maximum number of hops and uses RSSI value to modify its hop value when hop of an anchor node is 1. The first N anchor nodes with greater RSSI value is chosen as reference anchor nodes and per hop distance error of the reference anchor nodes are used to weight average hop distance of the unknown node. Finally，a total least squares method is used to calculate the coordinates of the position of the unknown node to achieve overall improvement of RMDV-Hop localization algorithm and improve the positioning accuracy. The simulation results show that the positioning accuracy and stability of the improved algorithm has been significantly improved than those of the original algorithm.

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