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Journal of Jiangsu University(Natural Science Eidtion)

	2013 Vol.34 Issue.3 Published 2013-05-10

	Article

Article

	249	Performance simulation and testing of multi-levels-damping adjustable hydraulic shock absorber
		CHEN Long, Yu-Li, CUI Xiao-Li
		The adjustable damping of traditional damping adjustable shock absorber was achieved mainly by changing throttle opening area with single work mode and limited damping adjustable range. In order to enhance the adjustable damping work mode and the adjustable range, a shock absorber with various state switching was designed based on a passive hydraulic shock absorber. In order to analyze the performance, a mathematical model for multilevelsdamping adjustable hydraulic shock absorber was established based on fluid mechanics and thermodynamics. The relation among shock absorber output force, piston travel and piston frequency was analyzed by Simulink simulation software and compared with the damping performance of adjustable shock absorber by bench test. The results show that the damping force deviation between test results and simulation results is small. The multi-levels-damping states of shock absorber change obviously with high switching control accuracy of damping state, which provides a basis for semi-active suspension control system.
		2013 Vol. 34 (3): 249-253 [Abstract] ( 2773 ) [HTML 1KB] [ PDF 1706KB] ( 4643 )

	254	Fine particle emission characteristics of light-duty gasoline vehicle on urban streets
		CHEN Xu-Dong, LI Tie-Zhu, YAN Zhen-Xing
		To investigate the fine particle emission instantaneous characteristics of a single light-duty gasoline vehicle on Nanjing urban streets, an on-road system of chassis dynamometer was set up to analyze the influences of vehicle speed, acceleration and driving modes on fine particles size distributions. For the on-road measurements, the number and the mass concentration of particles under acceleration condition are obviously higher than those under other driving modes. At low speed, the number concentration of fine particle in nucleic mode(Dp<50 nm) is higher than that at high speed, while the particle numbers in accumulation mode(50 nm<Dp<565 nm) at high speed is more than that at low speed. The average total number concentration in the chassis dynamometer tests is 1.62 times than that in on-road measurements, while the ratio of average mass concentration to that in on-road measurements is only 0.18. The particle number concentration with diameter lower than 100 nm accounts for a vast majority of the test range. More fine particles are emitted under high speed and hard acceleration condition. The results show that the proposed system is effective to investigate the fine particle emission characteristics from a light-duty gasoline vehicle at real urban road.
		2013 Vol. 34 (3): 254-260 [Abstract] ( 2549 ) [HTML 1KB] [ PDF 2256KB] ( 4499 )

	261	Characteristics analysis of mechanical transmission for a new mechanical elastic wheel
		WANG Wei, ZHAO You-Qun, JIANG Cheng, WU Jian
		To improve the tire performance of puncture-proof, explosion prevention and safety, a new mechanical elastic wheel used for offroad vehicle was proposed with main innovation of nonpneumatic elastic structure in wheel. The structure and the working principle of new mechanical elastic wheel were analyzed in detail. According to the loading experiment under wheels driving and braking work conditions, the results show that the moving relationship of each component in the wheel is basically the same with working principle. Under the driving and braking work conditions of new mechanical elastic wheels, the mechanical analyses of inner-wheel and outer-wheel were respectively conducted to obtain the mechanical transmission relationship of internal structure in wheel. The mechanical transmission dynamic simulation under driving and braking work conditions was conducted by ADAMS software, and the simulation results were also analyzed. The results show that the new wheel has effective mechanical transmission characteristics to ensure normal driving of car.
		2013 Vol. 34 (3): 261-266 [Abstract] ( 2342 ) [HTML 1KB] [ PDF 4155KB] ( 4613 )

	267	Numerical simulation of temperature gradient inside diesel particulate filter
		MENG Zhong-Wei, QIN Zong-Sheng, FU Rui
		Based on the onedimensional unsteady model, the influences of key parameters on the filter wall temperature gradients were investigated under the optimal flow rate. The key parameters include filter structure parameters of cell per square inch (CPSI), wall thickness δw, filter length L and thermal conduct factor λ and regeneration conditions of regeneration duration td and regeneration temperature Tmax. The numerical simulation results indicate that with the increase of CPSI, the (dT/dx)max gradually increases. The wall thickness δw has remarkable effect on the (dT/dx)max. When the δw is less than 0.3 mm, the (dT/dx)max decreases with the increase of δw, while the (dT/dx)max nearly remains constantly when the δw is more than 0.3 mm. With the increase of filter length L, the (dT/dx) max decreases sharply. When the λ is less than 1.0 W·(m·K)-1, the (dT/dx)max significantly decreases as the λ increases, the (dT/dx)max lineally decreases when the λ is more than 1.0 W·(m·K)-1. With the increases of regeneration duration time td and temperature Tmax, the (dT/dx)max increases gradually.
		2013 Vol. 34 (3): 267-271 [Abstract] ( 2583 ) [HTML 1KB] [ PDF 2215KB] ( 4039 )

	272	Filtration combustion instability with lean premixed hydrogen／air in porous media
		XIA Yong-Fang, Li Ben-Wen, YU Chun-Mei, SHI Jun-Rui, XU You-Ning
		The evolution of flame front inclination instability and the property of cellular structure combustion waves with hot spots were determined during the superadiabatic combustion wave propagation for different filtration velocity and hydrogen concentration. The dynamic factor leading to the filtration combustion wave instability was analyzed. The evolution mechanism and the characteristics for lowvelocity filtration combustion instability were verified. The results show that the flame front inclinational instability develops continuously when the flame has an initial tiny inclinational angle. When the experimental condition parameters are changed, the cellular structure combustion waves may emerge at the upstream side of the combustor. The cellular structure combustion waves have strong effect on the stability of the main combustion wave propagation, and can depress the main wave propagation velocity. When the main combustion wave leaves combustor, the cellular structure combustion waves distribute randomly and stand in combustor.
		2013 Vol. 34 (3): 272-275 [Abstract] ( 2238 ) [HTML 1KB] [ PDF 3803KB] ( 3961 )

	276	Simulation and experiment of impinged material surface with abrasive water jet
		KANG Can, ZHOU Liang, WANG Yu-Li, GONG Chen
		To investigate the mechanism of abrasive water jet cutting process with micro scale characteristics, the abrasive speeds at jet stream center, jet edge and average abrasive speed at the section with distance of 3.0 mm from nozzle outlet were calculated under operation jet pressure of 250 MPa. Finite element method was used to simulate the impact of steel plates with different thicknesses. The results show that the abrasive speed is relative small at the jet edge with little deformation on the steel plate, and little damage is appeared on the surface with bounced abrasive. Large deformation is appeared with apparent surface damage when the abrasive speed reaches the average speed, while the abrasives are embeded into the steel plate. Abrasives go through the plate directly at the jet center, and cause less deformation than that with abrasive speed at jet edge. The plate strain gradually decreases with the increase of thickness of steel plate at the same abrasive speed. The experiment was conducted under the same conditions, and the optical profilescanning device was used to examine the distributions of roughness. The simulation results are in good accordance with the experiment results.
		2013 Vol. 34 (3): 276-280 [Abstract] ( 1975 ) [HTML 1KB] [ PDF 4494KB] ( 3802 )

	281	Placement angle effect of axial and radial stent on ventilation structure in bulb tubular turbine
		SONG Hou-Bin, LI Wei-Li, YANG Feng-Yu
		According to the principle of wind turbine,a forward inclined support was designed on light bulb tubular turbine to study the heat dissipation effect of axial or radial direction ventilation structure. Based on the increasing of radial angle, the axial angle was changed to verify the simulation data by reliability verification tests. The results show that a reasonable increase of radial or axial angle can improve the heat dissipation performance and singlesided radial air intake. The maximum temperature of winding with radial angle of 15° is 3.4% lower than that with radial angle of 0°.The maximum temperature of winding with axial angle of 20° is 5.0% lower than that with axial angle of 40° when the radial angle is 15°. The optimal heat dissipation performance can be achieved with radial angle of 15° and axial angle of 20°,and the temperature of main heating components of electric generator in whole machine can be controlled not more than 55 ℃.
		2013 Vol. 34 (3): 281-286 [Abstract] ( 2295 ) [HTML 1KB] [ PDF 4135KB] ( 4706 )

	287	Design and experiment of new conditioning mechanism for mower conditioner
		GAO Dong-Ming, WANG De-Cheng, HAO Li-Ying, SUN Jie, FU Zuo-Li
		A new conditioning mechanism of mower conditioner was developed to solve the operation unhandiness of flattening roller. Operational requirements, working principle and mechanical properties of the conditioning mechanism were analyzed. Operational effectiveness and reliability were set as primary design goals with agronomic requirements as constraint conditions. Based on the theoretical analysis, the motion mechanism and the geometry parameters of flattening roll were calculated and developed to conduct the operating performance test. According to the evaluation criteria of flattening ratio, the levels of experimental factors were determined to obtain high operating efficiency.The results show that high flattening rate of 53.71% can be obtained under the conditions of small gap flattening roller and large compression ratio with staggered feeding.
		2013 Vol. 34 (3): 287-292 [Abstract] ( 1946 ) [HTML 1KB] [ PDF 1337KB] ( 2877 )

	293	Real-time citrus recognition and location based on TOF imaging technology
		SUN Li, CAI Jian-Rong, LI Yong-Ping, ZHAO Jie-Wen, YUAN Lei-Ming
		The intensity and depth information of reflected light were represented with image based on the analysis of TOF (time of flight) imaging technology. A new adaptive filter model coupling with partial differential equations filter and shock filter was established to remove noise and to sharpen edges efficiently. The algorithms of thresholding, region growing and smallest surrounding circle were used to segment mature citrus from the background. Depth range and variance within the selected region and radius of recognized citrus were calculated and used as constraint condition for further selecting of recognized citrus regions. Threedimensional database was integrated with extracted characteristic parameters of recognized citrus to realize realtime recognition and location. The total classification results show that recognition accuracy of about 86.7% can be obtained without false detection. The error of depth information is less than 12 mm with actual radius of citrus less than 13 mm. It takes less than 100 ms for image recognition and location.
		2013 Vol. 34 (3): 293-297 [Abstract] ( 2674 ) [HTML 1KB] [ PDF 1924KB] ( 4282 )

	298	Business process management system modeling based on object oriented Petri net
		LI Xiao-Zhong, ZHANG De-Long
		In order to meet the requirement of process variance with outside changes for business process management(BPM) system, the BPM framework supporting variable running process was proposed based on rule base. The object oriented Petri net (OOPN) model of the BPM frame was established for the tokens in the places to represent rules and processes. The simulation of the model was conducted by CPN Tools. The system model of given problem was built by the creation of CPN Tools. The analysis report of the model live ness and the space bounded ness were obtained by the state space of CPN Tools. The report of main token flows in places was obtained by monitors. The analysis report by Gnuplot illustrates that the system satisfies the stability requirements. The simulation shows that the model can simply express the system running process and reflect the scale of rule base during the system running process, which gives a consultation for enterprises to develop BPM system.
		2013 Vol. 34 (3): 298-303 [Abstract] ( 2065 ) [HTML 1KB] [ PDF 1920KB] ( 4038 )

	304	Half／full bridge of PWM switching control method for energy regeneration of electric vehicles
		CHENG Li, XI Jia-Jian, LI Ning, YAN Ming, WANG Zhen-Yu
		In order to obtain high charge current acceptance in energy regeneration for battery during electric brake of light electric vehicle(EV)， a half/full bridge of PWM switching control method was proposed. Based on a BLDCM PWM converter circuit， the switched special PWM control was realized by braking signal during normal and energyregeneration modes. The quick periodical swift charge and recharge for battery can be realized with high efficiency， and more energy can be returned in the energy regeneration period. The performance of the proposed method was compared with the Boost converter energy regeneration method through experiments. The results show that compared with the Boost converter energy regeneration method， the control method can decrease the average resistance of battery by 216 mΩ，and increase the average charge current acceptance by 6.2% with enhanced driving range of 6.6% for EV under the same driving condition.
		2013 Vol. 34 (3): 304-308 [Abstract] ( 2373 ) [HTML 1KB] [ PDF 1505KB] ( 4491 )

	309	Efficient and strongly unforgeable short signature scheme in standard model
		LIU Zhen-Hua, HU Yu-Pu, ZHANG Xiang-Song
		To solve the low efficiency of existing strongly unforgeable signature schemes in standard model, a new efficient signature scheme was proposed. Based on the computational DiffieHellman (CDH) hard problem assumption of bilinear pairing on elliptic curves, the proposed scheme was proved to be strongly unforgeable. For the proposed scheme, the public key contains six group elements with a single group element of secret key, and the signature includes two group elements. There are three exponential computations in the signing algorithm with one exponential and two pairing computations in the verification stage. The results show that compared with the existing strongly unforgeable signature schemes in standard model, the new scheme has a shorter length of public\\secret key and signature with decreased computation time of signing and verification algorithms. The proposed scheme is suitable for the constrained resource communication environments with high efficiency.
		2013 Vol. 34 (3): 309-313 [Abstract] ( 2070 ) [HTML 1KB] [ PDF 1169KB] ( 3633 )

	314	Survivability routing protocol of satellite networks based on random linear network coding
		HAO Xuan-Wen, MA Jian-Feng
		To solve the communication link break of satellite nodes invalidation by various attacks because of the openness of space communication, a survivability routing protocol of GEOLEO satellite network was designed based on the routing protocols of satellite network and random linear network coding. In view of satellite security management and communication problems, the GEO satellites group was used to manage different groups of LEO satellites when LEO satellites were main communication method. In order to improve the survivability and efficiency of routing, every LEO satellite was maintained with a onestep adjacent table updated with LEO satellite time period. When the original LEO satellites nodes needed routing, the protocol would search for the routing in the onestep adjacent table. If the target LEO satellites nodes were in the onestep adjacent table, the message would be sent through the onestep adjacent table of original LEO satellites. Otherwise, the original LEO satellites would produce a routing table during the searching for RREQ message through random linear network coding routing. The simulation results show that the proposed routing protocol can greatly improve the performance of survivability routing and reduce the times of routing message transmission.
		2013 Vol. 34 (3): 314-319 [Abstract] ( 2286 ) [HTML 1KB] [ PDF 1903KB] ( 4088 )

	320	An efficient certificatebased signature scheme with bilinear pairing
		HUANG Zhen-Jie, GUO Ya-Feng
		In order to improve the efficiency and guarantee the unforgery of certificatebased signature scheme, a new efficient certificatebased signature scheme was proposed based on the kbilinear DiffieHellman Inverse(kBDHI) problem and the Computational DiffieHellman (CDH) problem. The security of the proposed scheme was proved by random oracle model (ROM). According to the difficulty of kBDHI problem and the CDH problem, user public key and certificate generating algorithms were designed to guarantee the oneway of public key and certificate. User signature generating algorithm was also designed by the difficulty of kBDHI problem and the CDH problem to ensure signature oneway and unforgery. In the proposed scheme, no bilinear pairing computation was needed in the signature generate algorithm, and only one was need in verification algorithm. The efficiency of the proposed scheme was compared with those of the available certificatebased signature schemes. The results show that the proposed scheme is more efficient than the available certificatebased signature schemes.
		2013 Vol. 34 (3): 320-325 [Abstract] ( 2005 ) [HTML 1KB] [ PDF 1171KB] ( 3215 )

	326	Effect of arcultrasonic excitation current on joint properties of TIG welding MGH956 alloy
		LEI Yu-Cheng, CHENG Long, LI Meng-Gang, LIANG Shen-Yong
		Using original solder as filler composite, the arcultrasonic was motivated by modulating TIG arc at high frequency.The effects of arcultrasonic on pore distribution,microstructure and mechanical properties of MGH956 alloy joints produced by arcultrasonic TIG welding with different excitation current were investigated. The results show that the size of pores changes markedly with the increasing of excitation current，while the number decreases slightly. Arcultrasonic can break or reduce the growth of coarse columnar grain near the weld interface. The refined grains can be achieved by arcultrasonic in welding process with better effect for increased excitation current in a certain range.When the excitation current reaches 30 A，the grains are coarsened by high heat input. The maximum tensile strength of welding joint is 623 MPa with 23 A arcultrasonic，which is 86.5% of base metal strength.
		2013 Vol. 34 (3): 326-330 [Abstract] ( 2086 ) [HTML 1KB] [ PDF 6368KB] ( 3586 )

	331	Properties improvement of laser cladded TC4 Titanium alloy by laser shock processing
		WANG Cheng, LAI Zhi-Lin, AN Zhi-Bin, HE Wei-Feng, ZHOU Liu-Cheng
		The laser cladded samples of TC4 titanium alloy was shocked by pulse laser to compare the hardness, surface residual stress, microstructure and the fatigue life of samples before and after laser shock processing(LSP). The surface residual tensile stress in heat affect zone(AFZ) of laser cladded sample is 225 MPa.LSP reliefs the tensile stress and generates 449 MPa compressive stress, and the surface residual compressive stress after LSP in metal matrix reaches 672 MPa.The hardness in AFZ after laser cladding is 333 HV, while that is 381 HV after LSP. A nanocrystalline surface layer is found by TEM after three impacts. The high cycle fatigue tests of laser cladded samples were carried out before and after LSP. The results show that LSP treatment can improve the high cycle fatigue endurance limit of laser cladding titanium alloy by 158％. The nanocrystalline grained surface layer with residual compressive stress makes great contribution to the fatigue properties improvement of titanium alloy.
		2013 Vol. 34 (3): 331-334 [Abstract] ( 2208 ) [HTML 1KB] [ PDF 4254KB] ( 4296 )

	335	Properties of epoxy resin adhesive modified by nano-TiO2
		CHEN Yu-Fei, ZHANG Xu, SUN Jia-Lin, LIN Cai-Wei
		Using organic nano-TiO2 as modifier, TiO2/ PU-EP adhesive was prepared with epoxy resin toughened by polyurethane. Scanning electron microscopy analysis show that the "island structure" is formed between polyurethane and epoxy, and inorganic phase has good compatibility with polymer matrix. The mechanical properties, thermal stability, dielectric loss, dielectric constant and breakdown field strength of composites were investigated by electronic tensile machine, TGA, dielectric spectrum and voltage tester analyzer. The results indicate that the comprehensive performance can be improved by doping appropriate amount of nanoTiO2 . When the amount of TiO2 is 3%, the shear strength and thermal decomposition temperature of TiO2/ PUEP reach the maximum of 27.14 MPa and 397.82 ℃, respectively. Compared with PU-EP matrix, the shear strength is increased by 22.6% with enhanced thermal decomposition temperature of 17.48 ℃. Under the condition of power frequency, the dielectric constant and dielectric loss are 4.27 and 0.02, respectively, and the breakdown field strength of composite is 14.03 kV·mm-1.
		2013 Vol. 34 (3): 335-339 [Abstract] ( 2712 ) [HTML 1KB] [ PDF 1989KB] ( 4544 )

	340	Preparation,characterization of H6P2W18O62／SiO2 and catalyzing synthesis of tetrahydrofuran
		CAO Xiao-Hua, REN Jie, LIU Min-Sheng, XU Chang-Long
		Phosphotungstic acids with Dawson structure(H6P2W18O62) supported on SiO2 were prepared by sol-gel method. The Dawson structure of phosphotungstic acids after loading on SiO2 and 30％ H6P2W18O62 loading quantity are confirmed, and H6P2W18O62 can be well dispersed on the SiO2 support. The catalytic performance of H6P2W18O62／SiO2 was investigated by the catalytic synthesis of tetrahydrofuran from 1,4butanediol. The results of orthogonal experiments and simple factor experiments show that H6P2W18O62／SiO2 exhibits good catalytic performance for catalytic synthesis of tetrahydrofuran from 1,4butanediol. Under the optimal conditions with H6P2W18O62 of 66％ relative to the dosage of 1,4butanediol, reaction temperature of 185～190 ℃ and reaction time of 40 min, the isolated yield of tetrahydrofuran can reach 91.70％. The catalyst can be reused for five times with no evident decline of catalytic performance, and the isolated yield of tetrahydro-furan is still above 90.90％.
		2013 Vol. 34 (3): 340-344 [Abstract] ( 1851 ) [HTML 1KB] [ PDF 2264KB] ( 2638 )

	345	Effect of cyclic preshearing on liquefaction resistance and dynamic pore water pressure of saturated silt
		FENG Tu-Gen, WANG Fei, ZHANG Fu-Hai
		Under the conditions of different cyclic preshearing stress and cyclic preshearing vibration times, cyclic triaxial tests on saturated silt of Yellow River estuary were conducted by DDS70 microcomputer control electromagnetic vibration triaxial apparatus to study the liquefaction resistance and dynamic pore water pressure of saturated silt. The results show that the saturated silt is not failed under low cyclic preshearing stress in cyclic preshearing stage. The liquefaction resistance of saturated silt is increased with the increase of cyclic preshearing stress and cyclic preshearing vibration times. The liquefaction resistance reaches a stable value after a certain vibration times. Normalized relationship between vibration cycles and pore water pressure can be fitted by hyperbola and arcsine functions. The mode of pore water pressure is hyperbola without cyclic preshearing, while with it, the mode is arcsine with small fitting parameter of 0.2 to 0.4.
		2013 Vol. 34 (3): 345-350 [Abstract] ( 1362 ) [HTML 1KB] [ PDF 2329KB] ( 2269 )

	351	Analysis of seismic earth pressure for rigid retaining wall with inhomogeneous backfilled soil
		LIU Li-Biao, ZHANG Yong-Xing, CHEN Jian-Gong
		Seismic earth pressure of retaining wall is often calculated based on shearbeam models on the assumption of homogeneous backfilled soil at present. The discrete shearbeam mode was proposed to calculate the pressure of rigid retaining wall with inhomogeneous backfilled soil. The shear stiffness of the spring in nonhomogeneous backfilled soil was deduced by assuming the shear modulus distribution of power function with depth. According to the different varied shear modulus and seismic earth pressure distribution, the resultant earth pressure and acting point were analyzed. The calculated results based on the proposed model were compared with those from Veletsos model and Scott model. The results show that the distribution form of shear modulus has significant influence on seismic earth pressure increment distribution, the resultant earth pressure increment and the base shear increment, but has little influence on the application points of resultant earth pressures increment and the amplification factor of base shear increment.
		2013 Vol. 34 (3): 351-355 [Abstract] ( 1322 ) [HTML 1KB] [ PDF 1709KB] ( 2020 )

	356	Adsorption behavior of Th (IV) ion on a novel surface imprinting magnetic chitosan in aqueous solution
		HUANG Guo-Lin, CHEN Zhong-Sheng, LIANG Xi-Zhen, Shi Jeffrey
		The performance of a novel surface imprinting magnetic chitosan (SIMC), which was coated with magnetic fluids and crosslinked with epichlorohydrin and thorium ion as template agent, was investigated for the adsorption of thorium(IV) in aqueous solution. Infrared spectra and energy dispersive spectrometer before and after adsorption show that Th (IV) ion is successfully adsorbed onto the SIMC. The influences of adsorbent dosage, pH value of solution and contact time on the adsorption were discussed to obtain optimum process conditions. Experimental equilibrium data were determined and correlated by both Freundlich and Langmuir isotherms to calculate adsorption potential. The results show that the Langmuir isotherm model fits the experimental data well with maximum Th (IV) adsorption capacity of 95.2 mg·g-1. Two simplified models of pseudofirst order and pseudosecond order equation were used to fit the adsorption processes. The experimental data for the adsorption kinetics correlates well with the pseudosecond order equation. The adsorbed Th (IV) ions can be removed from the exhausted SIMC effectively with 1 mol·L-1 sulfuric acid solution.
		2013 Vol. 34 (3): 356-360 [Abstract] ( 1614 ) [HTML 1KB] [ PDF 1603KB] ( 2135 )

	361	DMTS production and water quality variation during decomposition of algal mats
		WANG Guo-Fang, LI Xian-Ning, FANG Yang, HUANG Rui, LV Xi-Wu
		Under the conditions of static state, thermostatic and shading, the mass concentration of typical smelly substrate dimethyl trisulfide (DMTS) and the change characteristics of other water quality indicators were determined. According to the observing apparent phenomena and analyzing smelly substrate, the relationship between two kinds of cell density of algalladen water and water quality was analyzed with cell density of 1.0×106 cells·L-1 as comparison sample. The results show that the produced DMTS concentration during the courses of dying and decomposing of algal mats shows significant correlation with the density of algae. The relationship between DMTS concentration and the density of algae fits linear and quadratic model. When the algae density is 1.0×107 cells·L-1, the concentration of DMTS reaches a maximum of 891.8 ng·L-1, about 90 times more than the odor threshold concentration with emitting appreciable odor. When the algae density is 1.0×108 cells·L-1, the concentration of organic matter increases gradually with the concentration of dissolved oxygen reduced to 0. The level of oxidationreduction potential drops to -300 to -400 mV with strong reduction characteristic, which can generate black sediment of ferrous sulfide and turn the water into black.
		2013 Vol. 34 (3): 361-366 [Abstract] ( 1435 ) [HTML 1KB] [ PDF 1402KB] ( 2404 )

	367	M/M/c queue of partial working vacation with N-policy and negative customer
		ZHU Yi-Juan, XU Hong-Yang
		The partial working vacations policy was considered based on conventional M/M/c queue. During the vacation period, some of servers do not entirely stop service, and service the new customers at a lower service rate, while the other servers stop service with a normal vacation. With the consideration of negative customers, Npolicy is introduced as vacation stopping policy. The negative customers only remove positive customers who are being served at the head of the queue one by one. When there is no positive customer in the system, the arrived negative customers will disappear automatically without service. At the end of a vacation, if the customer numbers in system are not less than N, the system will stop vacation. Otherwise, the system continues to have vacation. Based on quasi birth and death process and matrix geometric solution, the steady state distribution of queue length was obtained. The conditional stochastic decomposition was established for all busy servers.
		2013 Vol. 34 (3): 367-372 [Abstract] ( 1207 ) [HTML 1KB] [ PDF 1187KB] ( 2013 )

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