Showing papers by "Xi'an Jiaotong University published in 2005"

Intrinsically conducting polymers for electromagnetic interference shielding

Abstract: This paper summarizes and reviews the research on electromagnetic interference (EMI) shielding with intrinsically conducting polymers (ICPs), mainly polyaniline (PANI) and polypyrrole (PPY), and their composites in various frequency ranges. ICPs are new alternative candidates for EMI shielding applications due to their lightweight, corrosion resistance, ease of processing, and tunable conductivities as compared with typical metals. More importantly, the dominant shielding characteristic of absorption other than that of reflection for metals render ICPs more promising materials in applications requiring not only high EMI shielding effectiveness but also shielding by absorption, such as in stealth technology. Copyright © 2005 John Wiley & Sons, Ltd.

On the dynamical degradation of digital piecewise linear chaotic maps

Abstract: When chaotic systems are realized with finite precisions in digital computers, their dynamical properties are often found to be entirely different from the original versions in the continuous setting. In the literature, there does not seem to be much work on quantitative analysis of such degradation of digitized chaos and how to reduce its negative influence on chaos-based digital systems. Focusing on 1D piecewise linear chaotic maps (PWLCM), this paper reports some findings on a new series of dynamical indicators, which can quantitatively reflect the degradation effects on a digital PWLCM realized with a fixed-point finite precision. On top of that, the paper introduces a new method for studying digital chaos from an algorithmic point of view. In addition, the theoretical results obtained in this paper should be very helpful for the consideration of reducing negative influence of dynamical degradation in real design of various digital chaotic systems. As typical examples, the proposed dynamical indicators are applied to the performance comparison of different remedies for improving dynamical degradation, cryptanalysis of digital chaotic ciphers based on 1D PWLCM, and design of chaotic pseudo-random number generators with desired characteristics.

Computer-related technostress in China

Abstract: Technostress has been defined as any negative effect on human attitudes, thoughts, behavior, and psychology that directly or indirectly results from technology [8]. With the recent widespread application of IT and the Internet throughout China, technostress has become a serious issue for both users and IT professionals due to its potential effect on users' mental health and on-the-job productivity. Chinese employees are surrounded, often overwhelmed, by modern technology. The top 100 largest Chinese enterprises, accounting for 25% of China's GDP, are investing heavily ($10--$15 billion annually) in new IT applications, including enterprise resource planning systems. A 2002 report by the Chinese Ministry of Information Industry stated that there are 380 million mobile phone subscribers in China, making the country the world's largest mobile phone market. And a survey conducted in 2004 by the China Internet Network Information Center found that 87 million Chinese frequently accessed the Internet in 2004, an increase of 19 million, or 27.9%, over 2003.

In situ observation of reversible domain switching in aged Mn-doped BaTiO 3 single crystals

Abstract: Very recently, a giant recoverable electrostrain effect has been found in aged Fe-doped ${\mathrm{BaTiO}}_{3}$ single crystals; this effect is based on a defect-mediated reversible domain-switching mechanism. However, the reversible domain-switching process itself is yet to be directly verified. In the present study, we performed in situ domain observation during electric field cycling for an aged Mn-doped ${\mathrm{BaTiO}}_{3}$ single crystal and simultaneously measured its polarization $(P)$--field $(E)$ hysteresis loop. In addition, the electrostrain behavior of the sample was also characterized. Such experimentation made it possible to correlate the mesoscopic domain-switching behavior with the macroscopic properties. It was found that the aged sample shows a remarkable reversible domain switching during electric field cycling; it corresponds very well to a ``double'' hysteresis loop and a giant recoverable electrostrain effect (with a maximum strain of 0.4%). This provides direct mesoscopic evidence for our reversible domain-switching mechanism. By contrast, an unaged sample shows irreversible domain-switching behavior during electric field cycling; it corresponds to a normal hysteresis loop and a butterfly-type irrecoverable electrostrain behavior. This indicates that the reversible domain switching in the aged sample is related to point-defect migration during aging. We further found that the large recoverable strain is available over a wide frequency range. This is important for the application of this electrostrain effect.

Structures, Phase Transformations, and Dielectric Properties of Pyrochlores Containing Bismuth

Abstract: The structures, phase transformations, and dielectric properties of pyrochlore ceramics containing bismuth were studied. The relation between the orthorhombic and cubic pyrochlores in the Bi2O3-ZnO-Nb2O5 (BZN) system has been investigated. The effect of bismuth in distorted cubic pyrochlore structures is discussed. BZN compositions with pyrochlore structures have excellent dielectric properties, very low dielectric loss, and high dielectric constants with stable frequency and temperature dependence.

Gas slippage effect on microscale porous flow using the lattice Boltzmann method

Abstract: A lattice Boltzmann method is developed for gaseous slip flow at the pore scale in microscale porous geometries. Flow characteristics through various porous structures are studied for different Knudsen numbers and inlet to outlet pressure ratios. It is found that the gas permeability is larger than the absolute permeability of porous media due to the gas slippage effect. Furthermore, the rarefaction influence on the gas permeability is more evident for porous structures with low porosity. The Klinkenberg equation is confirmed for the simulated porous structures. However, the second-order term of the Knudsen number $({\mathrm{Kn}}^{2})$ cannot be neglected for gaseous flow with relatively high Knudsen numbers. A model for predicting the pressure drop of the flow through microscale porous media is presented based on the Ergun equation and the Carman-Kozeny equation by taking into account the effects of gas rarefaction and compressibility.

Alms1-disrupted mice recapitulate human Alström syndrome

Abstract: Mutations in the human ALMS1 gene cause Alstrom syndrome (AS), a progressive disease characterized by neurosensory deficits and by metabolic defects including childhood obesity, hyperinsulinemia and Type 2 diabetes. Other features that are more variable in expressivity include dilated cardiomyopathy, hypertriglyceridemia, hypercholesterolemia, scoliosis, developmental delay and pulmonary and urological dysfunctions. ALMS1 encodes a ubiquitously expressed protein of unknown function. To obtain an animal model in which the etiology of the observed pathologies could be further studied, we generated a mouse model using an Alms1 gene-trapped ES cell line. Alms1-/- mice develop features similar to patients with AS, including obesity, hypogonadism, hyperinsulinemia, retinal dysfunction and late-onset hearing loss. Insulin resistance and increased body weight are apparent between 8 and 12 weeks of age, with hyperglycemia manifesting at approximately 16 weeks of age. In addition, Alms1-/- mice have normal hearing until 8 months of age, after which they display abnormal auditory brainstem responses. Diminished cone ERG b-wave response is observed early, followed by the degeneration of photoreceptor cells. Electron microscopy revealed accumulation of intracellular vesicles in the inner segments of photoreceptors, whereas immunohistochemical analysis showed mislocalization of rhodopsin to the outer nuclear layer. These findings suggest that ALMS1 has a role in intracellular trafficking.

Application of serum SELDI proteomic patterns in diagnosis of lung cancer

Abstract: Currently, no satisfactory biomarkers are available to screen for lung cancer. Surface-Enhanced Laser Desorption/ionization Time-of- Flight Mass Spectrometry ProteinChip system (SELDI-TOF-MS) is one of the currently used techniques to identify biomarkers for cancers. The aim of this study is to explore the application of serum SELDI proteomic patterns to distinguish lung cancer patients from healthy individuals. A total of 208 serum samples, including 158 lung cancer patients and 50 healthy individuals, were randomly divided into a training set (including 11 sera from patients with stages I/II lung cancer, 63 from patients with stages III/IV lung cancer and 20 from healthy controls) and a blinded test set (including 43 sera from patients with stages I/II lung cancer, 41 from patients with stages III/IV lung cancer and 30 from healthy controls). All samples were analyzed by SELDI technology. The spectra were generated on weak cation exchange (WCX2) chips, and protein peaks clustering and classification analyses were made using Ciphergen Biomarker Wizard and Biomarker Pattern software, respectively. We additionally determined Cyfra21-1 and NSE in the 208 serum samples included in this study using an electrochemiluminescent immunoassay. Five protein peaks at 11493, 6429, 8245, 5335 and 2538 Da were automatically chosen as a biomarker pattern in the training set. When the SELDI marker pattern was tested with the blinded test set, it yielded a sensitivity of 86.9%, a specificity of 80.0% and a positive predictive value of 92.4%. The sensitivities provided by Cyfra21-1 and NSE used individually or in combination were significantly lower than that of the SELDI marker pattern (P < 0.005 or 0.05, respectively). Based on the results of the test set, we found that the SELDI marker pattern showed a sensitivity of 91.4% in the detection of non-small cell lung cancers (NSCLC), which was significantly higher than that in the detection of small cell lung cancers (P < 0.05); The pattern also had a sensitivity of 79.1% in the detection of lung cancers in stages I/II. These results suggest that serum SELDI protein profiling can distinguish lung cancer patients, especially NSCLC patients, from normal subjects with relatively high sensitivity and specificity, and the SELDI-TOF-MS is a potential tool for the screening of lung cancer.

Optimization of fractional order PID controllers based on genetic algorithms

Abstract: The intelligent optimization method for designing fractional order PI/sup /spl lambda//D/sup /spl delta// controller (FOPID) based on genetic algorithms is presented in this paper. Fractional calculus can provide new and good performance extension for FOPID because of the arbitrary order of fractional calculus. However, the difficulties of designing FOPID controllers increase. FOPID controllers' parameters are composed of proportional constant, integral constant, derivative constant, derivative order and integral order, whose design is more complex than that of conventional integer order PID controller. The optimization design process based on genetic algorithms is analyzed in detail in this paper, in which the optimization performance target is the combination of ITAE and control input, the numerical simulation of FOPID controllers uses the method of Tustin operator and continuous fraction expansion. Simulation results show the proposed method is highly effective.

Bone mesenchymal stem cells transplanted into rabbit intervertebral discs can increase proteoglycans.

Abstract: We sought to determine whether transplanted allogeneic bone mesenchymal stem cells can survive and increase the amount of proteoglycans in intervertebral discs. We used the rabbit intervertebral disc as a model, creating three groups: an uninjected control group, a group injected with saline, and a group injected with 1 x 10(5) of bone mesenchymal stem cells containing trace marker gene LacZ from young rabbits. At 1, 3, and 6 months, X-gal staining and DNA-polymerase chain reaction of the neomycin-resistant gene were used to ascertain cell location. Reverse transcription-polymerase chain reaction and enzyme-linked immunosorbant assay analysis were done to evaluate the effect on the disc matrix. Transplanted mesenchymal stem cells were located and identified in the group injected with mesenchymal stem cells, whereas we detected none in the saline and control groups. The amount of mRNA and protein of proteoglycan and collagen Type II in the mesenchymal stem cells group was increased, whereas the amount of collagen Type I did not change. We found no changes in the saline group. Our data suggest transplanted allogenic bone mesenchymal stem cells can survive and increase proteoglycan amount, supporting its potential use as a treatment of intervertebral disc degeneration.

Dominance relation and rules in an incomplete ordered information system

Abstract: Rough sets theory has proved to be a useful mathematical tool for classification and prediction. However, as many real-world problems deal with ordering objects instead of classifying objects, one of the extensions of the classical rough sets approach is the dominance-based rough sets approach, which is mainly based on substitution of the indiscernibility relation by a dominance relation. In this article, we present a dominance-based rough sets approach to reasoning in incomplete ordered information systems. The approach shows how to find decision rules directly from an incomplete ordered decision table. We propose a reduction of knowledge that eliminates only that information that is not essential from the point of view of the ordering of objects or decision rules. © 2005 Wiley Periodicals, Inc. Int J Int Syst 20: 13–27, 2005.

Operating reserve model in the power market

Abstract: Most of the current research on operating reserve markets assumes that the required capacity is predetermined, which means that the demand of operating reserve capacity is inelastic. This paper considers that operating reserve capacity in a power system is flexible and that one should optimize it by cost-benefit analysis. Based on the reliability evaluation of the generation system, a clearing model of the operating reserve market is proposed to determine the optimal reserve capacity and simultaneously clear the operating reserve market. The model is discussed on both uniform-price and pay-as-bid auction mechanisms. By using a heuristic method, we suggest an efficient algorithm to solve the model. Case studies for reliability test system (RTS96) demonstrate the usefulness and efficiency of the proposed model.

Attribute reduction theory and approach to concept lattice

Abstract: The theory of the concept lattice is an efficient tool for knowledge representation and knowledge discovery, and is applied to many fields successfully. One focus of knowledge discovery is knowledge reduction. This paper proposes the theory of attribute reduction in the concept lattice, which extends the theory of the concept lattice. In this paper, the judgment theorems of consistent sets are examined, and the discernibility matrix of a formal context is introduced, by which we present an approach to attribute reduction in the concept lattice. The characteristics of three types of attributes are analyzed.

Molecular Genetic Studies of Gene Identification for Osteoporosis: A 2004 Update

Abstract: This review summarizes comprehensively the most important and representative molecular genetics studies of gene identification for osteoporosis published up to the end of December 2004. It is intended to constitute a sequential update of our previously published review covering the available data up to the end of 2002. Evidence from candidate gene association studies and genome-wide linkage studies in humans, as well as quantitative trait locus mapping animal models are reviewed separately. Studies of transgenic and knockout mice models relevant to osteoporosis are summarized. An important extension of this update is incorporation of functional genomic studies (including DNA microarrays and proteomics) on osteogenesis and osteoporosis, in light of the rapid advances and the promising prospects of the field. Comments are made on the most notable findings and representative studies for their potential influence and implications on our present understanding of genetics of osteoporosis. The format adopted by this review should be ideal for accommodating future new advances and studies.

Optimal sizing of standalone hybrid wind/PV power systems using genetic algorithms

Abstract: Proper design of standalone renewable energy power systems is a challenging task, as the coordination among renewable energy resources, generators, energy storages and loads is very complicated. The types and sizes of wind turbine generators (WTGs), the tilt angles and sizes of photovoltaic (PV) panels and the capacity of batteries must be optimized when sizing a standalone hybrid wind/PV power system, which may be defined as a mixed multiple-criteria integer programming problem. In our research, we investigated the genetic algorithm (GA) with elitist strategy for optimally sizing a standalone hybrid wind/PV power system. Our objective is selected as minimizing the total capital cost, subject to the constraint of the loss of power supply probability (LPSP). The LPSP of every individual of the GA's population is calculated by simulation of 8760 hours in a year. Studies have proved that the genetic algorithm converges very well and the methodology proposed is feasible for optimally sizing standalone hybrid wind/PV power systems

Epidemic threshold conditions for seasonally forced seir models.

Abstract: In this paper we derive threshold conditions for eradication of diseases that can be described by seasonally forced susceptible-exposed-infectious-recovered (SEIR) models or their variants. For autonomous models, the basic reproduction number $\mathcal{R}_0 < 1$ is usually both necessary and sufficient for the extinction of diseases. For seasonally forced models, $\mathcal{R}_0$ is a function of time $t$. We find that for models without recruitment of susceptible individuals (via births or loss of immunity), max$_t{\mathcal{R}_0(t)} < 1$ is required to prevent outbreaks no matter when and how the disease is introduced. For models with recruitment, if the latent period can be neglected, the disease goes extinct if and only if the basic reproduction number $\bar{\mathcal{R}}$ of the time-average systems (the autonomous systems obtained by replacing the time-varying parameters with their long-term time averages) is less than 1. Otherwise, $\bar{\mathcal{R}} < 1$ is sufficient but not necessary for extinction. Thus, reducing $\bar{\mathcal{R}}$ of the average system to less than 1 is sufficient to prevent or curtail the spread of an endemic disease.