Showing papers by "Xi'an Jiaotong University published in 2004"
TL;DR: In this article, a new chaotic system is discussed and the forming mechanism of its compound structure obtained by merging together two simple attractors after performing one mirror operation has been investigated by detailed numerical as well as theoretical analysis.
Abstract: In this letter a new chaotic system is discussed. Some basic dynamical properties, such as Lyapunov exponents, Poincare mapping, fractal dimension, continuous spectrum and chaotic behaviors of this new butterfly attractor are studied. Furthermore, the forming mechanism of its compound structure obtained by merging together two simple attractors after performing one mirror operation has been investigated by detailed numerical as well as theoretical analysis.
539 citations
TL;DR: This paper presents a general framework for the study of rough set approximation operators in fuzzy environment in which both constructive and axiomatic approaches are used.
449 citations
TL;DR: The use of 1.5 SBF shortened the apatite induction time andApatite formation was confirmed even on the surface of the films oxidized at 350 V, which suggests that the incorporated Ca and P in the titania films play a similar role to the Ca- and P-containing compounds in the SBF.
412 citations
TL;DR: It is proved that for some special thresholds, β lower distribution reduct is equivalent to the maximum distribution reduction reduct, whereas β upper distribution reduCT is equivalents to the possible reduct.
388 citations
TL;DR: This work considers nonlinear extensions of Granger's idea and proposes a conditional extended Granger causality measure that enables us to determine whether the causal relation between two signals is direct or mediated by another process.
365 citations
TL;DR: This paper introduces the definitions for generalized fuzzy lower and upper approximation operators determined by a residual implication, and finds the assumptions which permit a given fuzzy set-theoretic operator to represent a upper (or lower) approximation derived from a special fuzzy relation.
364 citations
TL;DR: A predator-prey model is modified to include an SIS parasitic infection in the prey with infected prey being more vulnerable to predation, which allows the predator population to persist, when it would otherwise become extinct.
300 citations
TL;DR: In this article, the surface energies for 38 surfaces of FCC metals were calculated by using modified embedded-atom method and the results showed that, as predicted, the close-packed (1 1 1/1) surface has the lowest surface energy.
262 citations
TL;DR: Based on molecular dynamics simulation, the Young's moduli of carbon nanotubes are studied in this paper, where the inter-atomic short-range interaction and long-range interactions are represented by a second generation reactive empirical bond order (REBO) potential and Lennard-Jones (LJ) potential, respectively.
Abstract: Based on molecular dynamics (MD) simulation, the Young's moduli of carbon nanotubes are studied. The inter-atomic short-range interaction and long-range interaction of carbon nanotubes are represented by a second generation reactive empirical bond order (REBO) potential and Lennard–Jones (LJ) potential, respectively. The obtained potential expression is used to calculate the total potential energies of carbon nanotubes. Three types of single-walled carbon nanotubes (SWCNTs), armchair, zigzag and chiral tubules, are calculated, respectively. The computational results show that the Young's moduli of SWCNTs are in the range of 929.8±11.5 GPa. From the simulation, the Young's moduli of SWCNTs are weakly affected by the tube chirality and tube radius. The numeric results are in good agreement with the existing experimental results.
238 citations
TL;DR: In this article, the authors made a comparative study between single crystals and corresponding polycrystals and found that all single crystals exhibit normal two-stage transformation, being independent of Ni content.
233 citations
TL;DR: The convergence speed with the proposed improved genetic algorithm is faster than that with the penalty function method and the forced mutation method, and the result of placement optimization is better.
Abstract: The global optimization of sensor locations for structural health monitoring systems is studied in this paper. First, the performance function based on damage detection is presented. Then, genetic algorithms (GAs) are adopted to search for the optimal locations of sensors. However, the simple GAs can result in infeasible solutions to the problem. Some improved strategies are presented in this paper, such as crossover based on identification code, mutation based on two gene bits, and improved convergence. The analytical results from the improved genetic algorithm are compared with the penalty function method and the forced mutation method. It is concluded that the convergence speed with the proposed improved genetic algorithm is faster than that with the penalty function method and the forced mutation method, and the result of placement optimization is better.
TL;DR: Hpertrophic cardiomyopathy is not rare in China, but there are at least 1 million cases and the age- and sex-adjusted prevalence was about 80 per 100,000 adults.
TL;DR: Results demonstrate the direct involvement of hMR in HIV-1 infection of astrocytes and suggest that HIV- 1 interaction with hMR plays an important role in AIDS-1 neuropathogenesis.
Abstract: Human immunodeficiency virus type 1 (HIV-1) infection occurs in the central nervous system and causes a variety of neurobehavioral and neuropathological disorders. Both microglia, the residential macrophages in the brain, and astrocytes are susceptible to HIV-1 infection. Unlike microglia that express and utilize CD4 and chemokine coreceptors CCR5 and CCR3 for HIV-1 infection, astrocytes fail to express CD4. Astrocytes express several chemokine coreceptors; however, the involvement of these receptors in astrocyte HIV-1 infection appears to be insignificant. In the present study using an expression cloning strategy, the cDNA for the human mannose receptor (hMR) was found to be essential for CD4-independent HIV-1 infectivity. Ectopic expression of functional hMR rendered U87.MG astrocytic cells susceptible to HIV-1 infection, whereas anti-hMR serum and hMR-specific siRNA blocked HIV-1 infection in human primary astrocytes. In agreement with these findings, hMR bound to HIV-1 virions via the abundant and highly mannosylated sugar moieties of HIV-1 envelope glycoprotein gp120 in a Ca 2+ -dependent fashion. Moreover, hMR-mediated HIV-1 infection was dependent upon endocytic trafficking as assessed by transmission electron microscopy, as well as inhibition of viral entry by endosomo- and lysosomotropic drugs. Taken together, these results demonstrate the direct involvement of hMR in HIV-1 infection of astrocytes and suggest that HIV-1 interaction with hMR plays an important role in HIV-1 neuropathogenesis.
TL;DR: The third-order shear deformation plate theory (TPT) is employed to solve the axisymmetric bending and buckling problems of functionally graded circular plates.
TL;DR: Experimental results in different road scene and a comparison with other methods have proven the validity of the proposed method, and the architecture and strategy for the system are briefly described.
Abstract: This work presents the current status of the Springrobot autonomous vehicle project, whose main objective is to develop a safety-warning and driver-assistance system and an automatic pilot for rural and urban traffic environments. This system uses a high precise digital map and a combination of various sensors. The architecture and strategy for the system are briefly described and the details of lane-marking detection algorithms are presented. The R and G channels of the color image are used to form graylevel images. The size of the resulting gray image is reduced and the Sobel operator with a very low threshold is used to get a grayscale edge image. In the adaptive randomized Hough transform, pixels of the gray-edge image are sampled randomly according to their weights corresponding to their gradient magnitudes. The three-dimensional (3-D) parametric space of the curve is reduced to the two-dimensional (2-D) and the one-dimensional (1-D) space. The paired parameters in two dimensions are estimated by gradient directions and the last parameter in one dimension is used to verify the estimated parameters by histogram. The parameters are determined coarsely and quantization accuracy is increased relatively by a multiresolution strategy. Experimental results in different road scene and a comparison with other methods have proven the validity of the proposed method.
TL;DR: The numerical results demonstrate that the improved algorithms modified and improved can determine proper clusters and they can realize the advantages of the possibilistic approach.
Abstract: A possibilistic approach was proposed in a previous paper for C-means clustering, and two algorithms realizing this approach were reported in two previous papers. Although the possibilistic approach is sound, these two algorithms tend to find identical clusters. In this paper, we modify and improve these algorithms to overcome their shortcoming. The numerical results demonstrate that the improved algorithms can determine proper clusters and they can realize the advantages of the possibilistic approach.
TL;DR: The study showed that increasing methanol mass fraction of the diesel/methanol blends would increase the heat release rate in the premixed burning phase and shorten the combustion duration of the diffusive burning phase.
TL;DR: GERD is common in Xi'an's adult population with a mild or moderate degree, and the etiology and pathogenesis of GERD are probably associated with FD, IBS, and some respiratory, laryngopharyngeal and odontostological diseases or symptoms.
Abstract: AIM: Gastroesophageal reflux disease (GERD) is a common disorder in the Western population, but detailed population-based data in China are limited. The aim of this study was to understand the epidemiology of symptomatic gastroesophageal reflux (SGER) in adults of Xi’an, a northwestern city of China, and to explore the potential risk factors of GERD.
METHODS: Symptoms suggestive of GERD, functional dyspepsia (FD), irritable bowel syndrome (IBS), upper respiratory diseases and some potential risk factors were investigated in a face-to-face manner in a region-stratified random samples of 2789 residents aged 18-70 years in Xi’an by using a standardized questionnaire.
RESULTS: With a response rate of 91.8%, the prevalence of SGER was 16.98% (95% CI, 14.2-18.92) in Xi’an adults, and no gender- related difference was observed (P > 0.05). SGER was more common among subjects aged 30-70 years than in those aged 18-29 years (P < 0.05). The prevalence of SGER in rural, urban and suburban subjects was 21.07%, 17.44% and 12.12%, respectively, and there was a significant difference between rural, urban and suburban regions (P < 0.05). Compared with subjects without SGER, the prevalence of symptoms suggestive of FD and IBS, pneumonia, asthma, bronchitis, laryngitis, pharyngitis, chronic cough, wheeze, globus sensation, oral ulcer and snore was significantly increased in subjects with SGER (P < 0.01). Heavy smoking (OR = 4.94; CI, 3.70-6.61), heavy alcohol use (OR = 2.85; CI, 1.67-4.49), peptic ulcer (OR = 5.76; CI, 3.99-8.32), cerebral palsy (OR = 3.97; CI, 1.97-8.00), abdominal operation (OR = 2.69; CI, 1.75-4.13), obesity (OR = 2.16; CI, 1.47-3.16), excessive food intake (OR = 1.43; CI, 1.17-1.75), sweet food (OR = 1.23; CI, 0.89-1.54), and consumption of coffee (OR = 1.23; CI, 0.76-2.00) were independently associated with SGER. The episodes of GERD were commonly precipitated by dietary factors (66.05%), followed by body posture (26.54%), ill temper (23.72%), fatigue (22.32%) and stress (10.93%).
CONCLUSION: GERD is common in Xi’an’s adult population with a mild or moderate degree. The etiology and pathogenesis of GERD are probably associated with FD, IBS, and some respiratory, laryngopharyngeal and odontostological diseases or symptoms. Some lifestyles, diseases and dietary factors are the risk factors of GERD.
TL;DR: In this paper, a 3D model of the bony defect is generated after the acquisition of helical CT data and an individual tray is designed using freeform surfaces geometries and fabricated by rapid prototyping (RP) technology.
TL;DR: In this paper, the influence of the interface between electrode and polymer or polymer and polymer on the space charge dynamics has been studied, and it has been found that the types of interface between polymer and electrode play a significant role in determining the charge distribution in the insulation.
Abstract: This paper reports on an investigation into the space charge formation and decay at different material interfaces. In particular, the influence of the interface between electrode and polymer or polymer and polymer on the space charge dynamics has been studied. Planar samples were subjected to high DC electric stresses for extended periods of time and space charge measurements taken using the pulsed electroacoustic (PEA) technique. It has been found that the types of interface between electrode and polymer play a significant role in determining the charge distribution in the insulation and that the interface between polymer and polymer acts as a potential barrier to electrons while allowing positive charge carriers through easily.
TL;DR: An evacuation model—spatial-grid evacuation model (SGEM), which includes a pre-processing engine to assist in the transformation of the spatial information from computer-aided design (CAD) based architectural plans and perform a simulation to generate the escape patterns in many complex buildings.
TL;DR: In this article, the effects of dilute gas on burning velocities have been studied at the equivalence ratios from 0.7 to 1.2, and the explicit formula of laminar burning velocity for dilute mixtures is achieved.
TL;DR: In this article, high-porosity silicon carbide ceramic with a wood-like microstructure has been prepared by carbothermal reduction reaction of charcoal/silica composites in static argon atmosphere, which were fabricated by infiltrating silica sol into a porous biocarbon template from tilia amurensis wood using a vacuum/pressure infiltration process.
Abstract: Highly porous silicon carbide ceramic with a woodlike microstructure has been prepared by carbothermal reduction reaction of charcoal/silica composites in static argon atmosphere, which were fabricated by infiltrating silica sol into a porous biocarbon template from tilia amurensis wood using a vacuum/pressure infiltration process. The morphology of resulting porous SiC ceramic, as well as the conversion mechanism of wood to porous SiC ceramic, have been investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques. Experimental results show that the biomorphic cellular morphology of tilia amurensis wood charcoal tissue is remained in the porous SiC ceramic with high precision which consists of β-SiC with traces of α-SiC. The strut thickness of resulting SiC ceramic becomes thinner, even partially disappears with the increase of silica amount contained in the charcoal/silica composites. The morphology of the SiC ceramic reveals that solid–solid, gas–solid and gas–gas reactions occurred during the charcoal-to-ceramic conversion.
20 Jun 2004
TL;DR: In this paper, a new control scheme for parallel connected SPWM inverters is presented, which is based on auto-master-slave control technique, and the control circuitry employs the real power share bus and reactive power sharing bus interconnecting all the paralleled inverters.
Abstract: This work presents a new control scheme: auto-master-slave control technique of parallel connected SPWM inverters. The control scheme ensures a fast dynamic response and precise load current sharing capability. Based on auto-master-slave control technique, the control circuitry employs the real power share bus and reactive power share bus interconnecting all the paralleled inverters. With the power share buses and the power deviation controllers, the paralleled inverter with highest output power becomes the master inverter; other inverters become slave inverters. Master inverter drive the power bus, and the power deviations in slave inverter module are calculated by the power sharing controller. Hereafter, the inverters compensate for the frequency and amplitude of output voltage, and then the unbalance power was eliminated. An experiment system was built to verify this control scheme, and the results indicate the precise power balance performance for parallel operation.
TL;DR: The main route of HBV transmission from mother to fetus is transplacental, from the mother side of placenta to the fetus side, however, HBV intrauterine infection may take place through other routes.
Abstract: AIM: To explore the possible mechanism of intrauterine infection of hepatitis B virus (HBV).
METHODS: HBV DNA was detected in vaginal secretion and amniotic fluid from 59 HBsAg-positive mothers and in venous blood of their newborns by PCR. HBsAg and HBcAg in placenta were determined by ABC immunohistochemistry.
RESULTS: The rate of HBV intrauterine infection was 40.1% (24/59). HBV DNA was detected in 47.5% of amniotic fluid samples and 52.5% of vaginal secretion samples respectively. HBsAg and HBcAg were detected in placentas from HBsAg-positive mothers. The concentration of the two antigens decreased from the mother’s side to the fetus’s side, in the following order: maternal decidual cells > trophoblastic cells > villous mesenchymal cells > villous capillary endothelial cells. However, in 4 placentas the distribution was in the reverse order. HBsAg and HBcAg were detected in amniotic epithelial cells from 32 mothers.
CONCLUSION: The main route of HBV transmission from mother to fetus is transplacental, from the mother side of placenta to the fetus side. However, HBV intrauterine infection may take place through other routes.
TL;DR: In this paper, the synthesis of single-walled carbon nanohorns (SWNHs) by arc discharge between two graphite electrodes submerged in liquid nitrogen was reported. But this method does not require relatively expensive laser and vacuum equipment.
Abstract: We report on the synthesis of single-walled carbon nanohorns (SWNHs) by arc discharge between two graphite electrodes submerged in liquid nitrogen. The product in its powder form was found to consist of spherical aggregates with sizes in the range of 50–100 nm. The nanohorns are characterized by transmission electron microscopy (TEM), Raman and electron energy loss spectroscopies and surface area measurements. TEM observations revealed that the internal structure of the aggregates could be described as a mixture of ‘dahlia-like’ and ‘bud-like’. A structural transition above 300 ◦ Cw as inferred from the Raman data. Here we show that a simple technique that does not require relatively expensive laser and vacuum equipment provides an economical alternative for the synthesis of SWNHs.
TL;DR: In this article, the authors investigated the features of Love waves in a layered functionally graded piezoelectric structure, and the mathematical model was established on the basis of the elastic wave theory, and WKB method was applied to solve the coupled electromechanical field differential equation.
TL;DR: The comparison of the neuron state modeling and the local field modeling reveals an important stability invariance property of the two models, which lays a sound theoretical foundation of validity of a useful, cross-fertilization type stability analysis methodology for various neural network models.
TL;DR: In this article, an improved header configuration of plate-fin heat exchanger is put forward in order to enhance the uniformity of flow distribution, based on the analysis of the fluid flow maldistribution for the conventional header used in industry, a baffle with small holes of three different kinds of diameters is recommended to install in the header.
TL;DR: In this article, the effect of surface adsorbates on splat formation during thermal spraying is examined by controlling substrate adsorption, and it is shown that the existence of evaporable adsorates on the substrate surface influences significantly the splatting and consequently splat morphology.
Abstract: The effect of surface adsorbates on splat formation during thermal spraying is examined by controlling substrate adsorption. Splats are formed on a polished flat stainless steel substrate surface by plasma spraying. The adsorption state of the substrate is controlled with different organic substances of different boiling points and different preheating temperatures. The droplet materials used are aluminum, nickel, and Al 2 O 3 . Three kinds of organic substances used are xylene, glycol and glycerol, which are brushed on the surface of the substrate before spraying. It is revealed that when preheating temperature of the substrate is lower than the boiling point of the organic adsorbates on the substrate surface, the splashing occurs during droplet flattening which results in the formation of the splats with an irregular morphology. However, when the preheating temperature exceeds approximately 50 °C over the boiling point of the organic adsorbates and evaporates all organic substance adsorbed on the surface, the regular disk type splats are formed which corresponds to no occurrence of the splashing during splatting. It is clearly shown that the existence of the evaporable adsorbates on the substrate surface influences significantly the splatting and consequently the splat morphology. On the basis of the result, the evaporated-gas-induced splashing model is proposed to explain the occurrence of splashing during splatting of a spray molten droplet and the formation of the reduced splat. The effect of preheating temperature of a substrtae surface on water adsorption and desorption characteristics in ambient atmosphere is disscussed from the point of view to create a clean surface and regular disc splat.