Volume 37,Issue 3,2014 Table of Contents

1 An investigation on second phases in the as-cast Mg-3Al-1Zn-(0-0.5)Sr magnesium alloys

WU Lu , PAN Fusheng , YANG Mingbo , SONG Kai , PAN Hucheng

2014, 37(3):1-9. DOI: 10.11835/j.issn.1000-582X.2014.03.001

[Abstract](1830) [HTML](504) [PDF 10.75 M](1220)

Abstract:
In order to systematically investigate the effect of Sr addition on the second phases in the as-cast AZ31 magnesium alloy and provide the theoretical basis for the design of the Mg-Al-Zn series alloys containing Sr element，the type and formation theory of second phases in the AZ31 as-cast magnesium alloys with low Sr contents(mass friction of 0.1，0.3，and 0.5) are investigated and analyzed by using scanning electron microscope(SEM)，energy dispersive spectrometer(EDS)，differential scanning calorimetry(DSC)，and X-ray diffractometer(XRD). The results indicate that for the AZ31 as-cast alloy without Sr addition，besides the Mg17Al12 phase，the extra Mg21(Zn，Al)17 phase with small amount is found to exist in the alloy. In addition，the difference both in the volume fraction and the type for the second phases in the AZ31 as-cast alloys with different Sr contents is very obvious. The alloys with the addition of 0.1 and 0.3 Sr(mass friction) mainly consists of the α-Mg，Mg17Al12，Mg21(Zn，Al)17 and Al4Sr phases. However，only the α-Mg，Mg21(Zn，Al)17 and Al4Sr phases are observed for the alloy with the addition of 0.5 Sr(mass friction). Otherwise，the volume fraction of the Al4Sr phase with lamella-like sharps increases with the Sr contents increasing among the 0.3-0.5(mass friction) range.

2 Study on hot compression deformation behavior of a brush alloy Ag-Pd-Cu-X

WANG Yong , HU Jianqi , XU Yonghong , ZHANG Ying , TAN Chunlin , CHEN Rong

2014, 37(3):10-15. DOI: 10.11835/j.issn.1000-582X.2014.03.002

[Abstract](1297) [HTML](286) [PDF 7.84 M](1149)

Abstract:
Hot compression deformation of Ag-Pd-Cu-X alloy is performed on Gleeble-1500 thermal simulator with strain rates of 0.001~0.1 s -1 and temperature at 650~950 ℃. Variations of flow stress and microstructure are investigated. The flow stress constitutive equation of Ag-Pd-Cu-X alloy is established. The results indicate that the dominant softening mechanism shift from dynamic recovery to the dynamic recrystallization with the compression temperature increases from 650 ℃ to 750 ℃，the flow stress exhibits a gradual downward trend. While the alloy deforms at 750~ 950 ℃，and the activation energy is 210.369 kJ/mol. The stress values predicted by the constitutive equation demonstrate well agreement with the experimental results.

3 BP neural network and SQP algorithm for the optimization of wheel die cavity

XU Wujiao , LI Wuhua , WANG Yusong , JIANG Zhongyuan

2014, 37(3):16-22. DOI: 10.11835/j.issn.1000-582X.2014.03.003

[Abstract](1420) [HTML](344) [PDF 7.88 M](1117)

Abstract:
A method combining forging numerical simulation，BP neural network and SQP algorithm is developed to optimize the die cavity and reduce the wear of top die core，so as to improve die life. Optimal mathematical model is established for the purpose of equal wear and cubic spline interpolation curve is used to describe the shape of the forming part of top die core based on MATLAB. Then BP neural network is trained by the results of forging numerical simulation and modified Archard wear model to establish the relation between the control point of die cavity and the objective function. Finally，SQP algorithm is used to optimize the design variables and get the best shape of top die core. The results show that the wear of top die core decreases and becomes more uniform. The uniformity wear is reduced by 38.4% after optimization.

4 The application to simplify the complicated power grid through adjacent two-node equivalent method

LI Hongbing , LI Zhiyong , MU Zilong , LIAO Yuxiang

2014, 37(3):23-28. DOI: 10.11835/j.issn.1000-582X.2014.03.004

[Abstract](1477) [HTML](632) [PDF 5.91 M](1004)

Abstract:
Most real power systems are not radial networks and evaluation of the stability often needs to establish electromagnetic transient simulation models. So the network equivalent is required first and foremost. The adjacent two-node equivalent method, which considers the coupling impedance between equivalent nodes, is used to realize the simplification and modeling to complex power grid. The analysis and simulation on both the HVDC system from Deyang to Baoji and a real extra-high voltage AC transmission system in South China shows that the static performance of the simulated system by using the adjacent two-node equivalent method is completely equivalent to the original one, as well as the performance of dynamic equivalent is in a satisfied level. Thus the transient system model simplified can be well established to support research of power grid’s security and stability.

5 Parameter uncertainty analysis for probability distribution of bulk power systerm reliability

LU Jingjing , ZHAO Yuan , GUO Yin , ZHANG Xu

2014, 37(3):29-34. DOI: 10.11835/j.issn.1000-582X.2014.03.005

[Abstract](1634) [HTML](294) [PDF 7.31 M](976)

Abstract:
Component reliability parameters are of uncertainty and are affected by the component type, operation time, and weather conditions. So do the reliability indices of bulk power systems. The calculation of its probability distributions and its alteration law affected by parameters uncertainty are researched to provide practical engineering reference with exploring the impact of the parameter uncertainty on reliability assessment. The point estimate method is firstly proposed based on the two-loop Monte-Carlo simulation, and then the improved Monte-Carlo simulation is presented to enhance the calculation efficiency further. Moreover, their theories, merits and faults are explained in detail. It can be seen from the evaluation results for the RBTS power systems that the accuracy of the three methods are similar but the improved Monte-Carlo simulation has the highest efficiency, followed by the point estimate method. The IEEE-RTS 79 power system is evaluated by using the improved Monte-Carlo simulation, and the results verify its validity.

6 Influence of microwave radiation on phosphorus-removal process of oolitic high-phosphorus iron ore fines

TANG Huiqing , LIU Weidi , MA Long , LI Liuhui , GUO Zhancheng

2014, 37(3):35-40. DOI: 10.11835/j.issn.1000-582X.2014.03.006

[Abstract](1432) [HTML](294) [PDF 6.64 M](1165)

Abstract:
Influence of microwave radiation on newly proposed phosphorus removal process(gaseous reduction and slag/metal separation) is studied. Microwave radiation on the ore fines is carried out using MW-HS multi-function high temperature microwave reactor. The treated ore fines are subjected to examinations of SEM, EDS and TG. TG tests are conducted using thermal analyzer(LINSEIS STA PT 1600). Results show that microwave pretreatment can obviously change the microstructure of the ore fine. After microwave pretreatment, arc cracks develop along the boundaries between phosphorite phase and hematite phase and loose zones in the areas where multi-minerals coexist. Microwave pretreatment has an intesification effect in the late stage of the gaseous reduction of the ore fines. Results of gaseous reduction and melt separation tests indicate microwave pretreatment could greatly improve the metal recovery rate in processing the ore fines using the proposed phosphorus removal method while phosphorus content in the metal sample is slightly increased. Under the condtion that the reduction temperture is 1 273 K, reduction atmosphere full CO and reduction time 2 hours, metallization rate of the sample pretreated using microwave power of 450 W could reach 90%. And in the melting separation process, its metal recovery rate reaches 83% with a phosphorus content of 0.48%(mass percent) in the metal sample.

7 Preparation and properties of high stability magnetorheological fluid

TANG Long , LU Liping , YUE En , LUO Shun’an , ZHAO Guangming , ZHANG Ping , TANG Rui , ZHANG Dengyou , YANG Bailian

2014, 37(3):41-46. DOI: 10.11835/j.issn.1000-582X.2014.03.007

[Abstract](1932) [HTML](364) [PDF 7.14 M](1349)

Abstract:
The effect of nitriding on the carbonyl iron powder is characterized by XRD，SEM and vibrating sample magnetometer.With the nitride iron powder，a MR fluid with the excellent performance has been prepared through adding in thixotropic agent of organobentonite and polymeric surfactant. The magnetic properties，rheological properties，antisedimentation and aggregation stability，temperature stability，tribology properties and damping properties of MR fluid has been studied. The properties are listed as follows：shear stresses is more than 60 kPa(B=0.5 T)，off state viscosity is less then 1.0 Pa·s， and the three months settling rate is less than 10% and no hardening，easy redispersion. Temperature ranges from 20 to 125 ℃，and the maximum decay rate of the damping force is less then 14.3%.

8 Research of Al2O3 influences on the abrasion resistance of E-coatings on magnesium alloy

WU Chaoyun , ZHANG Jin , PAN Fusheng

2014, 37(3):47-52. DOI: 10.11835/j.issn.1000-582X.2014.03.008

[Abstract](1528) [HTML](334) [PDF 8.35 M](1107)

Abstract:
The cathodic electrodeposition coatings(E-coatings) with silane modifying ceramics are prepared on magnesium alloy for improving the abrasion resistance of organic E-coating. Hardness, adhesion, corrosion resistance, circle-drawing method and abrasion resistance are evaluated by pencil hardness, UMT abrasion test system, and Machu test. The results show that the abrasion resistance and hardness of E-coatings are enhanced by adding Al2O3 ceramic powders. Meanwhile, corrosion resistance and adhesion of E-coatings remain unchanged.

9 The effect of TiO2 nanofilms’ water sensitivity on the contamination resistance of coating

ZHANG Zhiqiang , YIN Feng , DUAN Dongfang , ZHANG Yuxin

2014, 37(3):53-57. DOI: 10.11835/j.issn.1000-582X.2014.03.009

[Abstract](1520) [HTML](345) [PDF 5.55 M](1179)

Abstract:
To improve the coating stain resistant performance using the photocatalytic activity of TiO2 is a hot research topic in recent years. In the article，hydrophilic TiO2 and hydrophobic TiO2 are prepared by hydrothermal method. The samples are characterized by X-ray diffraction(XRD) and transmission electron microscope(TEM). The results show that both the hydrophilic-TiO2 and hydrophobic-TiO2 are anatase，and the particle size of hydrophilic-TiO2 is 40 nm，while hydrophobic-TiO2 is only 7 nm. Moreover，the samples are employed for super-hydrophilic and super-hydrophobic coatings，respectively. The contact angle measurement is used to characterize the as-synthesized TiO2 coatings. The effect of the water contact angle on the contamination resistance is investigated. It is shown that the synthesized the hydrophilic TiO2 and hydrophobic TiO2 coatings both can remarkably improve the contamination resistance of the paint and the latter exhibited the better performance.

10 Knowledge discovery model of basic oxygen furance steelmaking based on Rough Set Theory

HU Yan , ZHENG Zhong

2014, 37(3):58-63. DOI: 10.11835/j.issn.1000-582X.2014.03.010

[Abstract](1639) [HTML](431) [PDF 5.03 M](1130)

Abstract:
The characteristics of the knowledge discovery for basic oxygen furnace(BOF) steelmaking are analyzed by using the Rough Set Theory. The production data of BOF steelmaking are preprocessed by using the methods of data withdrawal, standardization, discretization and so on. The main influencing factors of steelmaking production are set as the knowledge discovery property. The endpoint control objectives of BOF steelmaking are used as the decision attribute of knowledge discovery. Then the knowledge discovery model of BOF steelmaking based on rough set theory is established, which makes the automation of the production knowledge discovery, access and rule extraction come true. The model is tested by using the production data of 210 t BOF, and takes the temperature variation of smelting endpoint as the decision attribute. The results show that the influencing factors, such as silicon content, iron ore weight, oxygen consumption and so on, are of very importance to the endpoint temperature of molten steel. Besides, the rules of molten steel temperature extracted by the model vary with current converter steelmaking process, which proves the validity of the model.

11 The emission of N2O during single SBBR completely autotrophic nitrogen removal system

FANG Fang , ZHANG Qiang , CHEN Youpeng , LI Kai , LI Zhentao , GUO Jinsong

2014, 37(3):64-70. DOI: 10.11835/j.issn.1000-582X.2014.03.011

[Abstract](1585) [HTML](280) [PDF 7.19 M](1021)

Abstract:
Three single autotrophic denitrification biofilm reactors with artificial water are applied to study the influence of aeration treatments and carbon source on the N2O emission and N2O emission characteristics. The results show that the accumulative N2O emission amount and the conversion rate of N2O of reactor 1，2 and 3 in an operation cycle are 13.69，14.28，2.51 mg，and 1.36%，1.49%，0.236%，respectively. The comparative results of reator 1(continuous aeration) with reactor 2(intermittent aeration) show their accumulative N2O emission amounts and N2O conversion rates are similar. The accumulative N2O emission amount and the N2O conversion rate of reactor 3(organic carbon) are about 1/6 of those of reactor 2(without organic carbon). Aeration treatments have great influence on N2O emission characteristics，for reactor 1，the accumulative N2O emission amount increases persistently，the mean N2O emission rate and dissolved N2O concentration performance continue to decline after the first rise to the maximum. For reactor 2，N2O emissions are mainly in aeration period. The mean N2O emission rate and dissolved N2O concentration reduce after first increase. The N2O conversion rate of single autotrophic nitrogen removal process is lower than those of other biological denitrification processes.

12 Yield characteristics and critical condition of wall slip for sludge

FENG Minquan , TAN Wei

2014, 37(3):71-76. DOI: 10.11835/j.issn.1000-582X.2014.03.012

[Abstract](1781) [HTML](308) [PDF 6.67 M](1190)

Abstract:
In order to determine the yield characteristics as well as the critical shear stress value of dewatered sludge when wall slip occurs, the rotating rheometer with parallel plate(R/S +CPS) and high-speed cameras(Trouble Shooter) are used for dewatered sludge with low moisture content, at the same time, linear marker and the sensitivity of the yield stress to shear rate as well as the dependence of the shear stress-shear rate data to parallel plate spacing are adopted, thus the existence of the slip and the critical condition can be identified. The results show that the dewatered sludge with the moisture content of 83% under the shear rate of 5~60 s -1 show that the shear thinning, and because there may be the occurrence of wall slip, the yield stress is sensitive to shear rate, and its value decreases with the increase of shear rate. For the dewatered sludge with moisture content of 84%, 85% and 86%, the occurrence of wall slip is obviously observed. Comparing with multiple sets of shear stress-shear rate data under different working conditions finds it isn’t overlap; while for the moisture content as 88%, the results is just opposite. The wall slip velocity produced increases with the increase of wall shear stress. So shear stress and moisture content have some influences on wall slip velocity, and there even may be a critical shear stress.

13 Analysis effects and extent determination of boundary for numerical simulation of CO2 geologic sequestration

LEI Hongwu , LI Jiaqi , XU Tianfu , WANG Fugang , SHI Yan

2014, 37(3):77-86. DOI: 10.11835/j.issn.1000-582X.2014.03.013

[Abstract](1641) [HTML](665) [PDF 11.89 M](1073)

Abstract:
The extent and type of boundary directly affect numerical simulation results of CO2 geological sequestration in “infinite” deep saline aquifers thereby causes evaluation error of storage potential. In this paper, a typical 2D radial flow model is employed to analyze the effects of the extent and type of boundary on pressure buildup and CO2 saturation plume distribution, the maximum pressure buildup and CO2 migration distance after injecting CO2 into the deep saline aquifer using TOUGH2-MP software. To illustrate the relation between boundary effects and formation parameters, sensitivity analyses for permeability, compressibility, temperature, salinity, and boundary type are performed. The results indicate that the greater boundary extent leads to the more “average” pressure buildup and CO2 saturation, the smaller maximum pressure buildup, the more flat CO2 saturation distribution shape and the greater CO2 migration distance under no-flow boundary condition. But the boundary effects on storage forms are very small and the volume storage efficiency in the “infinite” deep saline aquifer is overestimated. The difference becomes smaller and smaller with the expansion of the boundary extent. In addition, according to analytical theory of single-phase and multiphase flow, one simple approximate analytical method for determining the boundary extent under a known injection rate is obtained. This method is applicable to boundary extent determination for single well or multi-well injection in the “infinite” deep saline aquifer and the maximum CO2 migration distance and effect boundary of single water phase is taken into account.

14 Purification and biological effect of Pistia stratiotes under different concentrations of livestock wastewater

CHEN Jinfa , YANG Ping , NIE Qishan , HU Jinzhao , QIN Ling , ZHANG Dan , HU Chenglun

2014, 37(3):87-94. DOI: 10.11835/j.issn.1000-582X.2014.03.014

[Abstract](1077) [HTML](336) [PDF 7.86 M](1190)

Abstract:
The clean and biological effect of Pistia stratiotes under different concentrations of livestock wastewater is first studied in indoor simulated conditions，which is collected from nature wetland. The correlation between clean and biological effect is also studied. The results show that the highest removal rates of CODcr，ammonia nitrogen，total phosphorus reach 82.33%，69.21% and 45.88% respectively. After 8 days of livestock wastewater stress，the enzyme activity of antioxidant system of Pistia stratiotes shows overall downtrend. The main protect enzyme in Pistia stratiotes is POD，whose variation range is the most obvious，and its sensitivity and irritability is the strongest. The correlation between removal effect and biological effect is substantially strong.

15 Analysis on rock cross-cut coal uncovering using high pressure water jet slotting in close distance seam group

LU Yiyu , HUANG Chen , JIA Yajie , YOU Yi , TANG Jiren

2014, 37(3):95-100. DOI: 10.11835/j.issn.1000-582X.2014.03.015

[Abstract](1567) [HTML](323) [PDF 8.04 M](1063)

Abstract:
Safe production and procedures at the driving face are restricted in mines of Guizhou province by the long periods required for rock cross-cut coal uncovering in high gas coal seam group. A new method is proposed to solve this problem using high pressure water jet slotting in penetration boreholes. This is proposed to increase the gas desorption rate and reduce drilling hole, which will shorten the cycle of rock cross-cut coal uncovering. Numerical simulation is used to compare the pressure relief effects of different slotting methods in penetration boreholes. The results show that the pressure relief effect of slotting all coal seams is more ideal. Field application indicates that high pressure water jet slotting has good effect of the pressure relief in coal seam group. The drilling number is reduced by 30, the drilling length is shortened by 610 m and the standard time of gas pre-pumping decreases by 39 days.

16 A calculation method for coalbed permeability by using drainage data

LAI Fengpeng , LI Zhiping , ZHANG Yuelei , FU Yingkun

2014, 37(3):101-107. DOI: 10.11835/j.issn.1000-582X.2014.03.016

[Abstract](1665) [HTML](343) [PDF 6.60 M](1142)

Abstract:
In order to more accurately calculate the changes in the permeability of coalbed during production process, a calculation method for coalbed permeability based on production data is established by combining with material balance equations and production equations, and it gives the fact that the output data can be a good reflection of the inner permeability of coalbed. The average pressure of coalbed in production process can be calculated through material balance equation. Dimensionless water production index is introduced into the production equation in the stage only with water production. In the next stage with both gas and water, gas and water production ratio is introduced to eliminate the influence of flush-flow radius, skin factor as well as other uncertain factors on the calculation of CBM permeability. The relationship between permeability and surface cumulative liquid production can be described as a single-variable cubic equation by derivation. There is a trend that the permeability declines firstly and then increases after wells in Qinshui CBM field are calculated. The results show that reservoir permeability increase after drainage stage, but the growth rate decrease gradually. The regression result of the permeability ratio and surface cumulative fluid production agrees with the theoretical mathematic relationship.

17 Communication method for electromechanical equipment on fully mechanized face with wirelessmesh network

ZHOU Xin , WANG Zhongbin , TAN Chao , LIU Xinhua , JI Rui

2014, 37(3):108-114. DOI: 10.11835/j.issn.1000-582X.2014.03.017

[Abstract](1676) [HTML](298) [PDF 7.47 M](894)

Abstract:
Aiming at the problem that the pre-existing communication condition can’t satisfy the dynamic movement of the electric & mechanical equipment on fully mechanized face, a wireless communication method based on mesh network is proposed. The design of the dual antenna and the dynamic distribution method of channels based on the interference perception which make the limited bandwidth sources can be rationally used. A high throughput routing protocol and a multipath routing control are used for the efficient management of the wireless mesh network. The factors which affect the signal strength are analyzed to research the deployment method of the wireless network adapt to the fully mechanized face. Experiments are carried out and the result shows that the signal strength of the wireless mesh network is -41~-68 dBm and the data transfer rate is above or equal 12 Mbps. Thus, the mesh network can satisfy the requirement of the electric & mechanical equipment and the method is a new way to solve the communication problem on fully mechanized face.

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