Showing papers by "Xi'an Jiaotong University published in 2006"
TL;DR: Li et al. as mentioned in this paper examined whether ownership structure and boardroom characteristics have an effect on corporate financial fraud in China and found that the proportion of outside directors, the number of board meetings, and the tenure of the chairman are associated with the incidence of fraud.
865 citations
15 Aug 2006
TL;DR: An online deterministic algorithm named BAR is presented and it is proved that it is 4.56-competitive, which improves the previous algorithm of Kim and Chwa which was shown to be 5-competitive by Chan et al.
Abstract: We study an on-line broadcast scheduling problem in which requests have deadlines, and the objective is to maximize the weighted throughput, i.e., the weighted total length of the satisfied requests. For the case where all requested pages have the same length, we present an online deterministic algorithm named BAR and prove that it is 4.56-competitive. This improves the previous algorithm of Kim and Chwa [11] which is shown to be 5-competitive by Chan et al. [4]. In the case that pages may have different lengths, we prove a lower bound of Ω(Δ/logΔ) on the competitive ratio where Δ is the ratio of maximum to minimum page lengths. This improves upon the previous $\sqrt{\Delta}$ lower bound in [11,4] and is much closer to the current upper bound of ($\Delta+2\sqrt{\Delta}+2$) in [7]. Furthermore, for small values of Δ we give better lower bounds.
669 citations
TL;DR: This work used CNE cells from a human nasopharyngeal carcinoma cell line as a cellular system to investigate miRNA-directed regulation of VEGF and other angiogenic factors under hypoxia, and to explore the principles of gene regulation by miRNAs.
Abstract: MicroRNAs (miRNAs) are a class of 20–24 nt non-coding RNAs that regulate gene expression primarily through post-transcriptional repression or mRNA degradation in a sequence-specific manner. The roles of miRNAs are just beginning to be understood, but the study of miRNA function has been limited by poor understanding of the general principles of gene regulation by miRNAs. Here we used CNE cells from a human nasopharyngeal carcinoma cell line as a cellular system to investigate miRNA-directed regulation of VEGF and other angiogenic factors under hypoxia, and to explore the principles of gene regulation by miRNAs. Through computational analysis, 96 miRNAs were predicted as putative regulators of VEGF. But when we analyzed the miRNA expression profile of CNE and four other VEGF-expressing cell lines, we found that only some of these miRNAs could be involved in VEGF regulation, and that VEGF may be regulated by different miRNAs that were differentially chosen from 96 putative regulatory miRNAs of VEGF in different cells. Some of these miRNAs also co-regulate other angiogenic factors (differential regulation and co-regulation principle). We also found that VEGF was regulated by multiple miRNAs using different combinations, including both coordinate and competitive interactions. The coordinate principle states that miRNAs with independent binding sites in a gene can produce coordinate action to increase the repressive effect of miRNAs on this gene. By contrast, the competitive principle states when multiple miRNAs compete with each other for a common binding site, or when a functional miRNA competes with a false positive miRNA for the same binding site, the repressive effects of miRNAs may be decreased. Through the competitive principle, false positive miRNAs, which cannot directly repress gene expression, can sometimes play a role in miRNA-mediated gene regulation. The competitive principle, differential regulation, multi-miRNA binding sites, and false positive miRNAs might be useful strategies in the avoidance of unwanted cross-action among genes targeted by miRNAs with multiple targets.
653 citations
TL;DR: Traditional family arrangements are beneficial in rural Chinese society as they represent the fulfillment of a cultural ideal and implications in the context of the corporate Chinese family are discussed.
Abstract: Objectives. The migration of working-age adults from rural to urban China has altered traditional patterns of living arrangements and intergenerational support among elderly persons who remain in rural regions. This investigation examined how household composition and support exchanges with adult children influenced the psychological well-being of older parents in rural China. Methods. Data derived from a 2001 survey of 1,561 parents aged 60 and older living in rural Anhui Province, China. We used multiple regression in order to estimate the effects of multigenerational living arrangements and intergenerational transfers of financial, instrumental, and emotional support on depression and life satisfaction in older parents. Results. Older parents living in three-generation households or with grandchildren in skipped-generation households had better psychological well-being than those living in single-generation households. Receiving greater remittances from adult children increased well-being and explained why living with grandchildren was beneficial. Stronger emotional cohesion with children also improved well-being. Discussion. These results suggest that traditional family arrangements are beneficial in rural Chinese society as they represent the fulfillment of a cultural ideal. We discuss implications in the context of the corporate Chinese family, characterized by mutual aid and interdependence across generations, and its adaption to social change.
536 citations
TL;DR: In this article, the laminar burning velocities and Markstein lengths of natural gas-hydrogen-air flames were obtained at various ratios of hydrogen to natural gas (volume fraction from 0 to 100%) and equivalence ratios.
516 citations
TL;DR: In this paper, a series of Cd 1 - x Zn x S ( x = 0 -0.92) photocatalysts were prepared by coprecipitation method and were calcined at 723 K under N 2 atmosphere.
440 citations
TL;DR: The special nanostep structure was observed at the surface of the sulfide photocatalyst, which was demonstrated to be crucial for the remarkable enhancement of photocatalytic hydrogen production.
Abstract: A novel method for the preparation of a CdS photocatalyst is presented. In this method, freshly prepared CdO obtained by decomposing cadmium acetate at a certain temperature was subjected to thermal treatment in the presence of H2S, which results in the formation of a highly stable and active CdS photocatalyst. In comparison to conventional preparation methods, CdS prepared by our method was found to be stable against both air oxidation and photocorrosion during a photocatalytic reaction. Most importantly, the special nanostep structure was observed at the surface of the sulfide photocatalyst, which was demonstrated to be crucial for the remarkable enhancement of photocatalytic hydrogen production. The apparent quantum yield at 420 nm and the energy conversion efficiency in the whole visible light region were determined to be 24.1% and 6.35%, respectively, in our experimental conditions.
431 citations
TL;DR: In this paper, an analytical study of the forced convection heat transfer characteristics in high porosity open-cell metal-foam filled pipes is presented. And the results show that the pore size and porosity of metal foams play important roles on overall heat transfer performance.
327 citations
TL;DR: In this paper, the effects of various parameters on biomass gasification in supercritical water were studied and the results showed that the gas yield of the biomass is sensitive to some of the parameters and the ways of reducing reactor plugging are obtained.
322 citations
TL;DR: In this paper, the authors summarized and reviewed the various synthesizing approaches of one-dimensional nano-structured polyaniline (PANI) and several potential applications of the nanomaterial.
Abstract: This paper summarizes and reviews the various synthesizing approaches of one-dimensional nano-structured polyaniline (PANI) and several potential applications of the nanomaterial. The synthesizing approaches can be generally categorized into template synthesis and non-template synthesis according to whether template(s), hard (physical template) or soft (chemical template), is (are) used or not. However, though the various approaches established, preparation of one-dimensional nano-structured PANI with controllable morphologies and sizes, especially well oriented arrays on a large scale is still a major challenge. Furthermore, the formation mechanisms of the nanostructures are still unclear. On the other hand, one-dimensional nano-structured PANI exhibits high surface area, high conductivity, as well as controllable chemical/physical properties and good environmental stability, rendering the nanomaterial promising candidate for application ranging from sensors, energy storage and flash welding to digital nonvolatile memory.
305 citations
TL;DR: Two new quantitative measures, “random certainty factor” and "random coverage factor" are associated with each decision rule are further proposed to explain relationships between the condition and decision parts of a rule in incomplete decision tables.
TL;DR: In this article, a single-domain (domain-wall-free) Mn-doped single crystal was used to study the aging behavior of its hysteresis loop.
Abstract: The change of ferroelectric, dielectric, and piezoelectric properties with time, the ferroelectric aging phenomena, has been observed in most ferroelectrics. Phenomenologically, aging can be attributed to the gradual stabilization of ferroelectric domains by defects, but the microscopic origin of the domain stabilization has remained controversial. It is unclear whether the domain stabilization is a boundary effect (caused by domain-wall-pinning) or a volume effect (stabilization of the whole domain). In the present paper, we made a single-domain (domain-wall-free) Mn-doped ${\mathrm{BaTiO}}_{3}$ single crystal and studied the aging behavior of its hysteresis loop. We found that after aging, the single-domain sample shows a significant increase in the coercive field, clearly indicating a strong stabilization of the single domain. Furthermore, the sample exhibits an abnormal double hysteresis loop, which corresponds to an interesting reversible domain switching process. These are direct evidence for the stabilization of single domain by aging. Our results preclude any explanation by the domain-wall-pinning effect and strongly suggest that the volume effect is the governing mechanism for the aging in hysteresis loop. We further show that the microscopic origin of the volume effect comes naturally from a general symmetry-conforming property of point defects. Such a microscopic mechanism can explain not only the aging in hysteresis loop (large signal aging) but also the aging in dielectric and piezoelectric constants (small signal aging), thus providing a unified microscopic explanation for all kinds of ferroelectric aging.
01 Jan 2006
TL;DR: The preliminary results show that this method can detect the falls effectively, and reduce the probability of being damaged in the experiments for the elderly people.
Abstract: The fall is a crucial problem in the elderly people’s daily life, and the early detection of fall is very important to rescue the subjects and avoid the badly prognosis. In this paper, we use a wearable tri-axial accelerometer to capture the movement data of human body, and propose a novel fall detection method based on one-class support vector machine (SVM). The one-class SVM model is trained by the positive samples from the falls of younger volunteers and a dummy, and the outliers from the non-fall daily activities of younger and the elderly volunteers. The preliminary results show that this method can detect the falls effectively, and reduce the probability of being damaged in the experiments for the elderly people.
TL;DR: These definitions result from the concept of cover introduced on a CCD lattice and improve the approximations of the existing crisp generalizations of rough sets with respect to similarity relation and covers, and a wider mathematical foundation for rough set theory is established.
TL;DR: In this article, the critical velocity of copper (Cu) particles for deposition in cold spraying was estimated both experimentally and theoretically based on the theoretical relationship between deposition efficiency and critical velocity at different spray angles.
Abstract: The critical velocity of copper (Cu) particles for deposition in cold spraying was estimated both experimentally and theoretically. An experimental method is proposed to measure the critical velocity based on the theoretical relationship between deposition efficiency and critical velocity at different spray angles. A numerical simulation of particle impact deformation is used to estmate the critical velocity. The theoretical estimation is based on the critical velocity corresponding to the particle velocity at which impact begins to cause adiabatic shear instability. The experimental deposition was conducted using Cu particles of different particle sizes, velocities, oxygen contents, and temperatures. The dependency of the critical velocity on particle temperature was examined. Results show that the critical velocity can be reasonably measured by the proposed test method, which detects the change of critical velocity with particle temperature and oxygen content. The Cu particles of oxygen content 0.01 wt.% yielded a critical velocity of about 327 m/s. Experiments show that the oxygen content of powder significantly influences the critical velocity. Variations in oxygen content can explain the large discrepancies in critical velocity that have been reported by different investigators. Critical velocity is also found to be influenced by particle temperature as well as types of materials. High particle temperature causes a decrease in critical velocity. This effect is attributed to the thermal softening at elevated temperatures.
TL;DR: Direct cell-to-cell contact between MSC and adult cardiomyocyte or SMC, but not the soluble signaling molecules is obligatory in the differentiation of MSC into cardiomeocytes orSMC.
15 Sep 2006-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, an excellent friction stir weld of AZ31 magnesium alloy was obtained at proper parameter, where the microstructure of the base material (BM) is replaced by fine grains and small particles of intermetallic compounds.
Abstract: Friction stir welding (FSW) is a relatively new joining technique particularly for magnesium and aluminum alloys that are difficult to fusion weld. In this paper, an excellent friction stir weld of AZ31 magnesium alloy was obtained at proper parameter. In the friction stir zone (FSZ), the microstructure of the base material (BM) is replaced by fine grains and small particles of intermetallic compounds. The average microhardness of the friction stir zone is higher than that of the base material. The maximum tensile strength of joint can reach 93% that of the base material. And the failure locations are almost at the heating affected zone.
TL;DR: It is found that higher support and confidence levels may not result in higher prediction accuracy, and a sufficient number of rules is a precondition for high prediction accuracy.
Abstract: Much current software defect prediction work focuses on the number of defects remaining in a software system. In this paper, we present association rule mining based methods to predict defect associations and defect correction effort. This is to help developers detect software defects and assist project managers in allocating testing resources more effectively. We applied the proposed methods to the SEL defect data consisting of more than 200 projects over more than 15 years. The results show that, for defect association prediction, the accuracy is very high and the false-negative rate is very low. Likewise, for the defect correction effort prediction, the accuracy for both defect isolation effort prediction and defect correction effort prediction are also high. We compared the defect correction effort prediction method with other types of methods - PART, C4.5, and Naive Bayes - and show that accuracy has been improved by at least 23 percent. We also evaluated the impact of support and confidence levels on prediction accuracy, false-negative rate, false-positive rate, and the number of rules. We found that higher support and confidence levels may not result in higher prediction accuracy, and a sufficient number of rules is a precondition for high prediction accuracy.
TL;DR: In this article, the combustion characteristics of a direct-injection natural gas engine under various fuel injection timings were investigated and the results showed that fuel injection timing had a large influence on the engine performance, combustion and emissions and these influences became largely in the case of late injection.
TL;DR: In this paper, the authors build a systemic conceptual model to describe the relationship among firm orientation, internal control systems and new product development, and to test empirically how market and entrepreneurship orientations affect the degree of improvement in product development through personal control and/or output control in the Chinese transitional economy.
TL;DR: In this article, a probabilistic load flow method considering random branch outages as well as uncertainties of nodal power injections is proposed, where the variations of the nodal voltages and line flows produced by normally and discretely distributed input variables are handled separately.
Abstract: This paper proposes a probabilistic load flow method considering random branch outages as well as uncertainties of nodal power injections. Branch outages are simulated by fictitious power injections at the corresponding nodes. A unified procedure is given to deal with random branch outages, generating unit outages, and load uncertainties by their moments and cumulants. The variations of nodal voltages and line flows produced by normally and discretely distributed input variables are handled separately. The method proposed by Von Mises is employed to solve the discrete distribution part of each state and output variable. The final distribution of a desired variable is obtained by simply convoluting its continuous and discrete distribution part. Results of 24-bus IEEE Reliability Test System are analyzed and compared to those obtained by Monte Carlo simulation. A numerical test on a real power system shows the effectiveness of the proposed method.
TL;DR: Wang et al. as mentioned in this paper carried out an empirical research to investigate the effects of main dimensions of HRM on technological innovation as well as organizational performance, and found that technological innovation is positively related with performance.
Abstract: Purpose – Human resource management (HRM) is seen as crucial for innovation and firm performance in China. This paper aims to carry out an empirical research to investigate the effects of main dimensions of HRM on technological innovation as well as organizational performance.Design/methodology/approach – The research uses a sample of 194 high‐tech firms surveyed in eight provinces in China.Findings – This research finds that employee training, immaterial motivation and process control have positive effects on technological innovation, while material motivation and outcome control have a negative influence on technological innovation. It is also found that technological innovation is positively related with performance.Research limitations/implications – This study does not consider the different influence of every HRM dimension affecting different innovation types. This should be a future research topic.Practical implications – This study provides useful managerial implication for managers. First, employ...
TL;DR: This model has represented the high rate of pedestrians' red light running and the mixed characteristics of traffic flows in Chinese cities, and it may be applicable in the micro-simulation of traffic system in other developing cities.
Abstract: In many Chinese cities, pedestrian’s road crossing behavior is different from that of pedestrians in developed countries. This paper presents a pedestrian model for traffic system micro-simulation in China. Considering the high rate of signal non-compliance, we classify pedestrians into two types: law-obeying ones and opportunistic ones. Opportunistic ones decide whether to violate traffic signal during red man, depending on the states of some external factors (like policeman, vehicle flow and other pedestrians’ behaviors). Questionnaires were used to determine the proportions of these two types of pedestrians under different circumstances. In addition, a time gap distribution extracted from videotape were used to determine the criterion for pedestrians to decide whether to walk or wait when they conflict with vehicle flows. However, simulation results deviate from the data extracted from videotape in some degree. By adjusting the parameters on the basis of analyzing the occurrence of the deviations, the simulation results agree with the field results better. This model has represented the high rate of pedestrians’ red light running and the mixed characteristics of traffic flows in Chinese cities, and it may be applicable in the micro-simulation of traffic system in other developing cities.
TL;DR: In this paper, the forced convection heat transfer characteristics in high porosity open-cell metal-foam filled tube heat exchangers are analyzed using the Brinkman-extended Darcy momentum model and two-equation heat transfer model for porous media.
TL;DR: In this article, a comprehensive review of the mathematical modeling of proton exchange membrane fuel cells is conducted, and the results computed by different models in the literature often agree well with the experimental data.
TL;DR: This paper proposes a hybrid genetic algorithm to solve the flexible job shop scheduling problem with non-fixed availability constraints (fJSP-nfa) and defines two kinds of neighbourhood for the problem based on the concept of critical path.
Abstract: Most flexible job shop scheduling models assume that the machines are available all of the time. However, in most realistic situations, machines may be unavailable due to maintenances, pre-schedules and so on. In this paper, we study the flexible job shop scheduling problem with availability constraints. The availability constraints are non-fixed in that the completion time of the maintenance tasks is not fixed and has to be determined during the scheduling procedure. We then propose a hybrid genetic algorithm to solve the flexible job shop scheduling problem with non-fixed availability constraints (fJSP-nfa). The genetic algorithm uses an innovative representation method and applies genetic operations in phenotype space in order to enhance the inheritability. We also define two kinds of neighbourhood for the problem based on the concept of critical path. A local search procedure is then integrated under the framework of the genetic algorithm. Representative flexible job shop scheduling benchmark problems and fJSP-nfa problems are solved in order to test the effectiveness and efficiency of the suggested methodology.
TL;DR: In this article, a general dynamic model is presented for studying the dynamic properties of rotor system supported by ball bearings under the effects of both internal clearance and bearing running surface waviness.
TL;DR: An adaptive segmentation algorithm based on a modified PCNN with the multi-thresholds determined by a novel water region area method is brought forward for region-based image fusion scheme using pulse-coupled neural network.
TL;DR: In this paper, a systematic examination of particle deformation behavior in cold spraying was conducted for Cu particle using both the Lagrangian and Arbitrary Lagrangians Eulerian (ALE) methods.
TL;DR: The δD of n-alkanes from 34 modern terrestrial plants, including twenty-one C3 plants and thirteen C4 plants from northwestern China, determined using gas chromatography/thermal conversion/isotope ratio mass spectrometry show that the stable hydrogen isotopes are poorly correlated with the plant photosynthetic pathway (C3 vs. C4) and that they do not give clear regional precipitation signals.
Abstract: Stable hydrogen isotopic compositions (δD) of compound-specific biomarkers, such as n-alkanes from plant leaf waxes, can be used as a proxy for paleoclimatic change. However, the relationship between hydrogen isotopes of plant leaf wax and plant ecological life forms is not well understood. Here, we report the δD of n-alkanes from 34 modern terrestrial plants, including twenty-one C3 plants and thirteen C4 plants from northwestern China, determined using gas chromatography/thermal conversion/isotope ratio mass spectrometry. Our data show that the stable hydrogen isotopes are poorly correlated with the plant photosynthetic pathway (C3 vs. C4) and that they do not give clear regional precipitation signals. Together with a comparative analysis of published δD values from plant leaf waxes in other regions, we believe that the stable hydrogen isotope of plant leaf waxes is more closely related to ecological life forms of these terrestrial plants (i.e. tree, shrub, and grass). In general, the grasses have more negative δD values than the co-occurring trees and shrubs. Our findings suggest that the δD values of sedimentary leaf waxes from higher plants may record changes of a plant ecosystem under the influence of environmental alteration and imply that reconstruction of the paleoclimate using δD values from plant n-alkanes should be based upon specific plant taxa, and comparison should be made among plants with similar ecological life forms.