Table of Content

30 April 2019, Volume 25 Issue 2

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Research Articles

Measurements of MIMO system using single-leaky coaxial cable in tunnel environment

KUANG Zhen, YIN Xiaoyu, WU Yiming, ZHENG Guoxin

2019, 25(2):  171-179.  doi:10.12066/j.issn.1007-2861.1896

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Usually, a multiple-input multiple-output (MIMO) system needs to deploy more than two leaky coaxial cables (LCXs). A $2\times 2$ MIMO system using a single LCX as transmitters was measured. Signals are fed from both ends of the LCX port separately, which can be used as two antennas. The results show that the performance of a single LCX system is close to that with two LCXs, and is much better than a single-input single-output system. The conclusion provides a reference for the design of LTE-M private communication networks.

Delay analysis of LTE-M in rail transit CBTC system

ZHANG Rui, ZHENG Guoxin, XIE Junjie

2019, 25(2):  180-188.  doi:10.12066/j.issn.1007-2861.1911

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LTE-M system is proposed to be used in the next generation of rail transit communication based train control (CBTC) system to achieved at a communication between the way side and vehicles. Such communications require low delay of data transit. Communication of vehicle terminal accessing the base station is modeled as M/M/1/m/m in the queuing theory. A method is developed to predict probability of data transit delay when LTE-M is used in CBTC. Related conditions are presented to meet the CBTC requirements. This study provides a reference for reliability design of the LTE-M system in the future.

A low-latency fault-tolerant routing algorithm for NoC without

virtual channelsLI Jiao, XU Haipeng, CHONG Yunfeng, LIU Peng, RAN Feng

2019, 25(2):  189-197.  doi:10.12066/j.issn.1007-2861.1918

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As the characteristic size becomes smaller, network on chip (NoC) is prone to faults. To improve fault-tolerant ability of NoC and reduce network latency, a low-latency fault-tolerant routing algorithm without using virtual channels is presented. Based on a turn model,the algorithm uses a bypass structure to keep a fixed direction connection of fault nodes. This way can reduce packet latency and deal with arbitrary amount and arbitrary distribution of fault nodes. Simulation results in an 8$\times $8 2D-Mesh NoC show that,compared with two reference algorithms, the proposed algorithm can reduce average latency by 4.35% and 20.20% with a single fault node and a communication load of 30%. It can also effectively deal with multiple faults.

Path planning of vascular access surgery based on improved ant colony algorithm

GAO Mingke, CHEN Yimin, ZHANG Dianhua, HUANG Chen, LI Zeyu

2019, 25(2):  198-205.  doi:10.12066/j.issn.1007-2861.1906

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Vascular access surgery is difficult and requires precise operation.Thick blood vessels are usually chosen for operation as doctors with different surgical skills generally do not consider possible optimal paths. This study proposes an improved ant colony algorithm to plan a vascular optimal path to assist surgeons with preoperative path planning. A globally optimal path is obtained by modifying a heuristic function and pheromone updated mechanism of the ant colony algorithm based on the overall consideration of factors such as catheter diameter, vascular length, minimal diameter, maximal curvature, maximal torsion, and introduction of end node factors.Experimental results show that the path planning is reasonable, the described algorithm is reliable and the method is feasible.

Effects of environment on mechanical properties of Al$_{\textbf{0.1}}$CoCrFeNi alloy

QIANG Xiaoni, CHEN Yexin, ZHANG Jiantao

2019, 25(2):  206-214.  doi:10.12066/j.issn.1007-2861.1915

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Effects of the environment on mechanical properties of Al$_{0.1}$CoCrFeNi alloy when tested in vacuum, air and gaseous hydrogen at different pressures were investigated. The result shows that a few hydrogen atoms can significantly improve elongation of the Al$_{0.1}$CoCrFeNi alloy when tested in air and gaseous hydrogen. The elongation of Al$_{0.1}$CoCrFeNi alloy increases with the increase of pressure of gaseous hydrogen. The increase rate of elongation becomes slower when the pressure of gaseous hydrogen is more than 0.010 MPa. Fractographs of Al$_{0.1}$CoCrFeNi alloy exhibits all transgranular fracture patterns. Some micro-voids exist on the fractograph surfaces when tensile test is performed in three environments.

Effect of steady magnetic field on wetting angles of liquids

CAO Yang, GUO Rui, HE Shengya, LI Chuanjun, XUAN Weidong, WANG Jiang, REN Zhongming

2019, 25(2):  215-221.  doi:10.12066/j.issn.1007-2861.1907

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Wetting angles of liquids such as deionized water and glycerol on the surface of plexiglass were measured using wetting angle goniometer. It was found that the wetting angles of the two liquids decreased with increasing magnetic field intensity. In the magnetic field of 5 T, decreases of wetting angles of two liquids were up to 10.8% and 4.0%, respectively. The phenomenon was attributed to the weakening of intermolecular interaction in liquids in a magnetic ield, reducing surface tensions of liquids and improving wetability of the two liquids.

Research Articles

Two-dimensional fractional discrete chaos combined with trigonometric functions

LIU Mingming, XIA Tiecheng, WANG Jinbo

2019, 25(2):  222-226.  doi:10.12066/j.issn.1007-2861.1934

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A discrete chaotic map combined with trigonometric functions is generalized to fractional ones. Through numerical simulation, the chaos behaviors of the maps are discussed by bifurcation diagrams,solutions and phase portraits when the difference orders are fractional.

Synjournal and luminescence properties of Bi$_{\textbf{2}}$S$_{\textbf{3}}$ quantum Dots

AN Baoli, ZHU Xiaoya, XU Jiaqiang

2019, 25(2):  227-234.  doi:10.12066/j.issn.1007-2861.1973

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Bismuth sulfide is considered as an environment-friendly material.Here, $Bi_{2}$$S_{3}$ quantum dots ($Bi_{2}$$S_{3}$ QDs) were synthesized with a new method using 11-mercaptounde-canoic acid as a capping agent. The $Bi_{2}$$S_{3}$ QDs showed stable properties over 6 months in the atmosphere. The maximum emission wavelength for $Bi_{2}$$S_{3}$ QDs was 500 nm. The ligand exchange process between S$^{2-}$ and acetylacetonate was a critical step in the synjournal of $Bi_{2}$$S_{3}$ QDs. Spherical cores of $Bi_{2}$$S_{3}$ were formed by the nuclei due to the orientation-directed effect of acetylacetonate. The Bi$^{3+}$ ions at the surfaces of $Bi_{2}$$S_{3}$ QDs were capped by 11-mercaptoundecanoic acid molecules that could efficiently stabilize the $Bi_{2}$$S_{3}$ QDs.

Structural design and mechanical analysis of C/C grids for ion thruster

CHEN Yue, LI Kai, PENG Yuqing, LI Aijun, ZHANG Dongsheng

2019, 25(2):  235-244.  doi:10.12066/j.issn.1007-2861.1922

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To design C/C grids for the ion thruster and estimate lateral stiffness of the C/C grids, the mechanical behavior of C/C composite grids is studied based on the geometry of molybdenum grids. Finite element models of acceleration and screen grids are established using ABAQUS. By introducing a periodic boundary condition, a homogeneous model is established to analyze the stress distribution and mechanical properties of the representative volume element. The effect of mechanical properties of the composite components on global lateral stiffness of the grids is then discussed, and compared with molybdenum grids. The results show that global lateral stiffness of C/C grids is a function of tensile modulus of the carbon fiber and the modulus of matrix. Higher tensile modulus of carbon fiber can be selected to improve lateral stiffness of C/C grids.

Monte Carlo simulation for mixing degree in two-component system

JIANG Zhi, SHEN Jie, LU Zhiming

2019, 25(2):  245-255.  doi:10.12066/j.issn.1007-2861.1972

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Multi-component aggregation has important applications in areas such as dispersion of active ingredients in a pharmaceutical process, formation of raindroplets, and crystallization. In this paper, a population balance equation with composition dependent kernel is numerically simulated using multiple Monte Carlo methods. The results show that the moments of a two-component system have a scaling behavior similar to a single component system regardless of the kernel type. While the degree of mixing reaches a constant value and the segregation index decreases by $1/\overline {v}$, the system approaches a self-preserving state. A fitted function of the stable value of the power density of excess component A on collision efficiency is derived.

Lattice Boltzmann method for simulation of flow with high Reynolds number

CHEN Yanxiao, LI Xiaowei, DING Jue, WENG Peifen

2019, 25(2):  256-265.  doi:10.12066/j.issn.1007-2861.1933

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A local time step technique for the generalized interpolation lattice Boltzmann method (GILBM) with the body-fitted grid is developed to improve stability and accelerate convergence of airfoil flow simulation at a high Reynolds number. The difficulty in dealing with complex boundaries in the LBGK model is overcome by introducing the non-equilibrium extrapolation boundary treatment. Flows of NACA0012 airfoil within the range are simulated. Advancement of the method is verified by comparing efficiency and stability of the calculation with traditional GILBM.

Distribution and profiles of perfluorinated compounds in surrounding surface water around a specific point-source in Shanghai

XIA Xiaoyu, WU Minghong, XU Gang, SUN Rui, TANG Liang

2019, 25(2):  266-274.  doi:10.12066/j.issn.1007-2861.1917

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A large quantity of aviation hydraulic fluid containing PFCs is used in airplanes in one of the international airports in Shanghai. It is also used in the airport interior and the nearby fire station. In fire drills or emergencies, Aqueous film-forming foams (AFFFs) is used. PFCs is an important component of AFFFs. Its excessive use may cause fluoride pollution in the neighboring surface water. In this study, 10 surface water samples were collected in the airport to detect 17 types of perfluormated compounds (PFCs). The results show that perfluorooctanoic acid (PFOA) is the predominant PFC, in the range from 37.55 ng/L to 189.05 ng/L, with a mean value 94.05 ng/L. Concentrations of perfluoro pentanoic acid (PFPeA) and perfluorobutane sulfonate (PFBS) in the surface water samples are in the range from 15.15 ng/L to 42.33 ng/L with a mean value 27.82 ng/L, and from 5.35 ng/L to 57.27ng/L with a mean value 24.12 ng/L,respectively. The detection rates were all 100%. The risk quotient was used for PFC in the surface water samples, showing that PFC in water had no ecological risk temporarily.

Effects of Brassica chinensis intercropping leguminous green manure on vegetable quality and soil enzyme activities

LI Menglu, HU Xuefeng, DAI Huihui, LUO Fan, ZHANG Peifeng, AN Bonian

2019, 25(2):  275-281.  doi:10.12066/j.issn.1007-2861.1916

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To study the effects of intercropping of leguminous green manure on the growth of Brassica chinensis, a field experiment was carried out in the suburb of Shanghai. The experiments included there treatments: single cropping of $\textit{Brassica chinensis}$, intercropping of $\textit{Brassica chinensis}$ and Chinese milk vetch ($\textit{Astragalus sinicus}$ L.), and intercropping of $\textit{Brassica chinensis}$ and Spring vetch $\textit{(Vicia gigantean Bge.}$). The results show that intercropping of leguminous green manure can significantly increase the plant height and sprout yield of the vegetable. Especially, intercropping of Chines milk vetch increased the yield of vegetable sprouts by 28.4%. Moreover, intercropping of leguminous green manure can also improve vegetable quality and raise activities of soil enzymes significantly. Intercropping of $\textit{Brassica chinensis}$ and Chines milk vetch can increase the contents of soluble proteins and soluble sugar in the vegetable sprouts by 33.6% and 73.6%, and raise activities of urease, sucrose and phosphatase by 23.8%, 22.2% and 23.9%, respectively. This can reduce application of chemical fertilizer and improve both the vegetable yield and quality, providing a better mode of $\textit{Brassica chinensis}$ cultivation.

Comparative assessment of human exposure to phthalate esters and bisphenol A from different indoor dust

LIU Wenlong, WANG Yujie, LIU Ye, SUN Yan, WU Minghong, MA Jing

2019, 25(2):  282-292.  doi:10.12066/j.issn.1007-2861.1909

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The concentrations and profiles of 7 phthalate esters and bisphenol A in 97 indoor dust samples collected from urban residential houses, shopping markets, college dormitories, and offices in Shanghai. Seven phthalate esters and bisphenol A were found at detection rate of 100\% in all samples. The sum concentrations of seven phthalate compounds ranged from 127.00 to 3 130.00 μg/g, with a median value of 542.00 μg/g. DEHP is the major phthalate esters found in indoor dust samples, ranging from 85.40 to3 040.00 μg/g, with a median concentration of 399.00 μg/g. Bisphenol A ranged from 0.20 to 4.70 μg/g, with a median value of 0.65 μg/g. The concentrations of phthalate esters were found to be the highest in offices, following by residential houses, college dormitories, and shopping markets, while the concentrations of bisphenol A were found to be the highest in offices and shopping markets, following by college dormitories and residential houses. The daily intakes (DI) of phthalate esters and bisphenol A were estimated through the route of dust ingestion for various age groups. The values of DI of phthalate esters and bisphenol A were 2 250.00 and 2.27 ng/kg-bw/day, respectively for toddlers, which were relative higher than those for adults. The incremental lifetime cancer risk (ILCR) model taking into account DEHP inhalation routes is used to quantitatively estimate the exposure risks for three age groups of female and male adults, adolescents, and children. According to the age groups, the values of ILCR in a decreasing order are as following: $I_3$(adult)$>I_2$(adolescent)$>I_1$(child), and the values of ILCR is higher for females than for males.

Preparation of nanoparticles poly ionic liquid via RAFT dispersion polymerization of ionic liquid monomer

ZHOU Jiamin, Lü Xiaoqing, ZHU Anqi

2019, 25(2):  293-300.  doi:10.12066/j.issn.1007-2861.1908

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Polymer nanoparticles have applications in biology, pharmacy, catalyst, etc. Polymerization-induced self-assembly is highly efficient for the synjournal of nanoparticles with different morphologies. Since ionic liquids have many unique properties, they have found wide applications such as catalysis, nanotechnology and biotechnology. Ionic liquid [MTMA] [TFSA] as a monomer is used for reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization in ethanol, and PDMAEMA$_{46 }$ as a macromolecular chain transfer agent to self-assembly to prepare diblock copolymer nanoparticles. As the degree of polymerization of the second block increases, the size of particles tends to increase substantially.

Preparation of CuO/EMT zeolite composite materials and its application in the non-enzyme glucose biosensor

HUANG Wenfeng, CHEN Jinyang, WANG Yingdi, ZOU Mihua

2019, 25(2):  301-308.  doi:10.12066/j.issn.1007-2861.1944

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An EMT zeolite with a high specific surface area, an open pore structure and a small particle size was synthesized under extremely mild conditions in a simple system. Composite materials of EMT zeolite loaded with CuO nano-particles were obtained by impregnation and calcination. The material was used in the preparation of non-enzyme glucose sensor, showing features of fast response, wide linear range and low detection.

Classification of upper and middle leaves of tobaccos based on aromatic

Huizhong DONG, Yanjiu BI, Xiaohua ZHAO, Jiong GE, Yunfei SHA

2019, 25(2):  309-316.  doi:10.12066/j.issn.1007-2861.1985

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The difference of aromatic components in the upper part and middle part of tobacco leaves was analyzed. Eleven different aromatic components, including solanone, dihydroactinidiolide and megastigmatrienone, were separated successfully through the HPLC-GC-MS system. Then eight aromatic components were selected as the major variants that caused the difference in tobacco odor by genetic algorithm. After that, a model that distinguishes the upper part and middle part of tobacco leaves was establishedby support vector machine. The accuracy of the proposed model, Leave-one-out cross-validations and the accuracy for forecasting unknown samples reached 88.65%, 84.40% and 82.86%respectively. Finally, Fisher discriminant vector method was used to distinguish the distribution of aroma on the upper part and middle part of tobacco leaves. The result shows that 3-hydroxy-$\beta $- dihydrogen ketone, megastigmatrienone and solanone were three major aromatic components that contribute to the difference in the upper part and middle part of tobacco leaves. This study is meaningful in that it provides help for tobacco leaves quality control and aroma control in the tobacco industry.

Experimental research and numerical simulation of interface between ribbed geomembrane and geotextile

GAO Junli, LI Houwei, CAO Wei

2019, 25(2):  317-327.  doi:10.12066/j.issn.1007-2861.1928

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To study the effect of ribbed geomembrane on stability of a landfill liner system, an indoor model test of the ribbed geomembrane liner system is designed. According to the principle of orthogonal test, considering shape, height and space of the rib, ten test cases are designed to study the settlement of the liner system. Analysis results show that optimal values exist. The optimal rib space is between 175 mm and 400 mm, and the optimal rib height is between 4.5 mm and 6.0 mm. On this basis, numerical simulation of the model test is carried out using the particle flow software PFC$^{\rm 2D}$. It has been shown that the PFC simulation can well fit the indoor load-settlement model. The sandy soil particles operation and stress change neared ribbed geomembrane can be obtained. The track and force mechanism of the internal particle in the model are revealed.

Analysis of soil pressure and displacement on bucket-based structure under reclamation silt

CAO Yaozhong, YAO Wenjuan, CHENG Zekun

2019, 25(2):  328-336.  doi:10.12066/j.issn.1007-2861.1932

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The bucket-based structure is a new type of hydraulic structure that can better adapt to hostile environments such as deeper water, big waves, and silt soils of low bearing capacity. Its stability depends mainly on the deadweight of barrel structure and interaction of the barrel and earth to resist external loads. Therefore, the level and distribution of soil pressure are primary factors in the calculation of bucket foundation revetment structure. In view of practical engineering, a 3D elasto-plastic finite element model is established to analyze interaction between the structure and the soil. Analyses of the soil pressure and the barrel's vertical and circular distributions are performed with different thickness of reclamation silt. It is compared with the calculation results of the soil's limit equilibrium using the Rankine's soil pressure theory. The traditional formula for active and passive soil pressure is revised, and displacement of the structure with different thickness of reclamation silt is also analyzed. Calculation error in soil pressure between the traditional and the proposed methods is 25%, and the bucket-based structure as a whole tilts toward the land reclamation silt side. The maximum angle is 1.24 times larger than that without reclamation silt, and the maximum subsidence is 1.16 times.

Constitutive model for unsaturated sedimentary soils based on SFG model

ZHANG Zhao, SUN Dean, GAO You

2019, 25(2):  337-346.  doi:10.12066/j.issn.1007-2861.1930

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The Sheng-Fredlund-Gens (SFG) model is modified by considering coupled water-retention and mechanical behavior to reflect the behavior of unsaturated sedimentary soils. The net stress is replaced with the average skeleton stress for stress state variable, and the influence of saturation on deformation is considered in the model. Based on test data of pre-consolidated clay at constant suctions for isotropic compression and triaxial shear, relationship between degree of saturation and void ratio is found, and the effect of deformation on saturation is considered in modeling the soil-water retention curve (SWRC). The loading collapse yield surface equation is derived from the volume change equation and SWRC equation. On the basis of a modified Cam-clay model, constitutive equations in triaxial stress state are derived with a unified hardening parameter that can describe shear contraction and dilatancy consistently. Using the same values of the model parameters, the hydraulic and mechanical behavior of unsaturated pre-consolidated clay can be consistently predicted under control of suction along isotropic compression and triaxial stress paths.

Short-term wind pressure forecast using LSSVM based on hybrid intelligent algorithm optimization

TU Weiping, LI Chunxiang

2019, 25(2):  347-356.  doi:10.12066/j.issn.1007-2861.1919

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Least squares support vector machine (LSSVM)is used to predict wind pressure on building surfaces. To enhance the generalization performance and prediction accuracy of LSSVM for wind pressure, LSSVM based on combination of ant colony optimization (ACO) and particle swarm optimization (PSO) is proposed to find optimal parameters. The combination avoids shortcomings in ACO and PSO, and achieves complementary focus of both. Using LSSVM based on ACO+PSO,wind pressure is forecast. It is compared with ACO-based LSSVM and PSO-based LSSVM, respectively. The numerical analysis shows that the proposed method can improve prediction accuracy and robustness of LSSVM, and has good prospects in engineering applications.