34 results on '"Zhang, Weidong"'
Search Results
2. Adaptive sequential design for phase II single-arm oncology trials: an expansion of Simon’s design.
- Author
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Gao, Ping and Zhang, Weidong
- Abstract
Single-arm phase II trials are very common in oncology. A fixed sample trial may lack sufficient power if the true efficacy is less than the assumed one. Adaptive designs have been proposed in the literature. We propose a Simon’s design based, adaptive sequential design. Simon’s design is the most used fixed sample design for single-arm phase II oncology trials. A prominent feature of Simon’s design is that it minimizes the sample size when there is no clinically meaningful efficacy. We identify Simon’s trial as a special group sequential design. Established methods for sample size re-estimation (SSR) can be readily applied to Simon’s design. Simulations show that simply adding SSR to Simon’s design may still not provide desirable power. We propose some expansions to Simon’s design. The expanded design with SSR can provide even more power. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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3. A new robust output feedback control for a class of uncertain nonlinear systems.
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Jain, Jitendra Kumar, Zhang, Weidong, and Ghosh, Sandip
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NONLINEAR systems , *UNCERTAIN systems , *BACKSTEPPING control method , *NONLINEAR functions , *ADAPTIVE control systems , *PSYCHOLOGICAL feedback - Abstract
This paper presents studies on a robust adaptive output feedback stabilisation for a class of nonlinear systems, which is subjected to parametric uncertainties and disturbances. The disturbances are considered to be general, i.e. both the matched and unmatched ones are present. A novel robust adaptive control is developed for this problem. A technique is employed to avoid the difficulty in handling the nonlinear gain functions associated with the disturbances. For this, a new Lemma is obtained to handle the nonlinear functions that simplify the controller derivation steps. The unknown parameters and disturbances are tackled by deriving the tuning functions using a backstepping design. Finally, simulation is carried out to validate and show the effectiveness of the proposed robust controller. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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4. H2 input load disturbance rejection controller design for synchronised output regulation of time-delayed multi-agent systems with frequency domain method.
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Ye, Fei and Zhang, Weidong
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TIME delay systems , *MULTIAGENT systems , *DECOMPOSITION method , *TRANSFER functions , *PRODUCTION (Economic theory) , *ROBUST control - Abstract
An analytical H2 input load disturbance rejection (ILDR) controller design approach is presented for the synchronised output regulation (SOR) of homogeneous time-delayed multi-agent systems. First, a closed-loop multi-input multi-output framework with transfer functions is introduced, and an SOR condition is given. Second, the decomposition method is utilised to simplify the analysis of internal stability and H2 performance index of the whole system to a set of independent optimisation problems with respect to the eigenvalues of the topology matrix. Finally, for each decomposed subsystem, the H2 optimal ILDR controller can be computed from all the stabilising controllers. By comparison with the conventional given-structured controllers, the contributions of the new approach are that the design procedure is calculated analytically for multi-agent systems with input disturbances, and a simple quantitative tuning way is developed to trade-off the nominal performance and robustness. The simulation example shows the effective ILDR capability of the proposed control strategy. [ABSTRACT FROM AUTHOR]
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- 2019
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5. Advancing cancer drug development through precision medicine and innovative designs.
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Zhang, Weidong, Wang, Jing, and Menon, Sandeep
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INDIVIDUALIZED medicine , *DRUG development , *TREATMENT effectiveness , *CANCER treatment , *BIOMARKERS - Abstract
Precision medicine has been a hot topic in drug development over the last decade. Biomarkers have been proven useful for understanding the disease progression and treatment response in precision medicine development. Advancement of high-throughput omics technologies has enabled fast identification of molecular biomarkers with low cost. Although biomarkers have brought many promises to drug development, steep challenges arise due to a large amount of data, complexity of technology, and lack of full understanding of biology. In this article, we discuss the technologies and statistical issues that are related to omics biomarker discovery. We also provide an overview of the current development of biomarker-enabled cancer clinical trial designs. [ABSTRACT FROM AUTHOR]
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- 2018
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6. Robust output feedback H∞ control for networked control systems based on the occurrence probabilities of time delays.
- Author
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Guo, Chenyu, Zhang, Weidong, and Bao, Jie
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ROBUST control , *FEEDBACK control systems , *ARTIFICIAL neural networks , *TIME delay systems , *UNCERTAINTY (Information theory) , *PERFORMANCE evaluation , *LINEAR systems , *APPLICATION software - Abstract
This article is concerned with the problem of robust H ∞ output feedback control for a kind of networked control systems with time-varying network-induced delays. Instead of using boundaries of time delays to represent all time delays, the occurrence probability of each time delay is considered in H∞ stability analysis and stabilisation. The problem addressed is the design of an output feedback controller such that, for all admissible uncertainties, the resulting closed-loop system is stochastically stable for the zero disturbance input and also simultaneously achieves a prescribed H∞ performance level. It is shown that less conservativeness is obtained. A set of linear matrix inequalities is given to solve the corresponding controller design problem. An example is provided to show the effectiveness and applicability of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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7. Effect of Membrane Structural Characteristics on Mass Transfer in a Membrane Absorption Process.
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Zhang, Weidong, Chen, Geng, Sun, Wei, and Li, Jiang
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MASS transfer , *POROSITY , *GAS flow , *CARBON dioxide adsorption , *ABSORPTION - Abstract
Carbon dioxide is absorbed by de-ionized water or NaOH aqueous solution in the unsteady-state membrane absorption process. A theoretical model has been developed to describe the mass transfer behavior in the liquid phase, in which the effects of membrane structural characteristics are investigated. The concentration profiles in the liquid phase are calculated as a function of time. When the membrane porosity is relatively high or the pore size is relatively small, the solute concentration profile near the membrane surface can get homogeneous instantly due to the short distance between adjacent pores. In this case, the existence of the porous membrane has less effect on the mass transfer process. However, when the membrane porosity is relatively low or the pore size is relatively large, the distance between the adjacent pores is large, so the concentration profile near the membrane surface is hard to get homogeneous during the absorption process. Therefore, the concentration profile can be influenced significantly by the membrane structural characteristics, which means that the membrane structure has a significant effect on the mass transfer in liquid phase. Moreover, the chemical reaction in the liquid phase makes it difficult for the concentration profile near the membrane surface to get homogeneous. The disturbance in the liquid phase caused by the gas flow and pressure fluctuation is also taken into account in the model, and the model results agree well with the experimental data. [ABSTRACT FROM AUTHOR]
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- 2010
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8. Textural Characteristics and Sensory Evaluation of Cooked Dry Chinese Noodles Based on Wheat-Sweet Potato Composite Flour.
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Zhang, Weidong, Sun, Cailing, He, Fengli, and Tian, Jichun
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NOODLES , *MATERIALS texture , *SENSORY evaluation , *SWEET potatoes , *WHEAT , *POTATO flour , *COOKING - Abstract
Effects of sweet potato flour (SPF) addition on dry Chinese noodles prepared from five wheat flours with variable quality (weak to very strong) were investigated. Color values expressed as L*, a* and b* were markedly affected by the levels of SPF. SPF addition reduced the springiness, cohesiveness, and resilience of the cooked noodles, but exerted varied effects on hardness and adhesiveness. Total scores of noodle samples prepared from composite flours decreased significantly with exception of very strong or strong flour. However, the reduction of total scores in wheat-SPF noodles was mainly due to decreasing of color and taste scores. [ABSTRACT FROM AUTHOR]
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- 2010
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9. Atom Transfer Radical Polymerization of Methyl Methacrylate High Efficiently Initiated by Azo-containing Iniferter.
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Zhang, Weidong, Zhang, Wei, Cheng, Zhenping, Zhou, Nianchen, and Zhu, Xiulin
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PHENYL compounds , *CARBAMATES , *METHYL methacrylate , *POLYSTYRENE , *COPOLYMERS - Abstract
Two novel azo-containing iniferters, (4,4'-(diazene-1,2-diyl) bis(4,1-phenylene) bis(2-(diethylca-rbamothioylthio)-2-methylpropanoate (BDCMP) and 4-((4-bromophenyl)diazenyl)phenyl-2-(diethylcarbamothioylthio)-2-methylpropanoate (PDCMP) were synthesized and used successfully as the initiators for atom transfer radical polymerization of methyl methacrylate (MMA). The kinetic plots were first order and the molecular weights of the polymers with narrow molecular weight distributions increased with the monomer conversions. Furthermore, the results showed that the apparent initiation efficiencies (f was close to 0.90 defined as Mn(th)/Mn(GPC)) of BDCMP and PDCMP were both higher than that (f was lower than 0.5) of 2-N,N-(diethylamino)dithiocarboyl-isobutyrate (EDCIB), which was reported previously by us (14). The obtained mono- and bi-functional PMMAs containing azo and N,N-diethyldithiocarbamate (DC) groups were confirmed by 1H-NMR and ultraviolet absorption spectra, respectively. The block copolymer, poly (methyl methacrylate)-b-polystyrene (PMMA-b-PS), was also successfully prepared via the ATRP chain-extension experiment using the obtained PMMA as a macroinitiator. [ABSTRACT FROM AUTHOR]
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- 2008
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10. The Influence of Chemical Reaction on Mass Transfer Behavior in the Membrane Absorption Process.
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Gao, Jian, Zhang, Weidong, Chen, Shu, and Zhang, Zeting
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ABSORPTION , *BIOLOGICAL membranes , *MASS transfer , *CHEMICAL processes , *POLYPROPYLENE , *THERMOPLASTICS - Abstract
Special reaction systems were proposed to investigate the mechanism of the mass transfer process in the membrane absorption process. The mass transfer resistance of this process was calculated by using hydrophobic polypropylene (PP) hollow fiber membrane (HFM); and a 2-order partial differential model, including reaction, was developed to describe the SO 2 and CO 2 absorption process using HFM. Throughout the experimental analyzing and model results, for either SO 2 /air/NaOH system or CO 2 /air-NaOH system, different phenomena in these two systems were discussed. Since the reaction mechanisms of both the SO 2 -NaOH system and the CO 2 -NaOH system were different, the SO 2 and CO 2 mass transfer in liquid side were different. The relation between the chemical reaction mechanism and mass transfer, instead of the ionized effect, was the reason for deviation in SO 2 absorption process. The influence of liquid phase velocity and the concentration of absorbent on the mass transfer process was also discussed. [ABSTRACT FROM AUTHOR]
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- 2005
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11. A developed observer-based type-2 fuzzy control for chaotic systems.
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Sabzalian, Mohammad Hosein, Mohammadzadeh, Ardashir, Rathinasamy, Sakthivel, and Zhang, Weidong
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FUZZY control systems , *FUZZY systems , *FUZZY logic , *ADAPTIVE fuzzy control - Abstract
This study presents a novel observer-based fuzzy control for chaotic systems (CSs). A class of CSs with unmeasurable states, unknown input constraints and unknown dynamics is taken to account. A generalised type-2 (GT2) fuzzy logic system (FLS) is formulated to approximate the uncertainties. The parameters of GT2-FLS are adjusted through the tuning rules that are extracted from robustness investigation. The proposed method is applied on CSs and it is demonstrated that the suggested observer and control system result in good performance in versus of disturbances, uncertainties, unknown and time-varying input nonlinearities, unmeasurable states and noisy faults. Comparison with other type of fuzzy systems demonstrates that the proposed GT2-FLS based controller is more effective. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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12. Electron inducing soft errors in 28 nm system-on-Chip.
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Yang, Weitao, Li, Yonghong, Zhang, Weidong, Guo, Yaxin, Zhao, Haoyu, Wei, Jianan, Li, Yang, He, Chaohui, Chen, Kesheng, Guo, Gang, Du, Boyang, and Luca, Sterpone
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NUCLEAR energy , *ELECTRONS , *SOFT errors , *SYSTEMS on a chip - Abstract
The 28 nm system-on-chip (SoC) was irradiated by 12 MeV electron at the China Institute of Atomic Energy (CIAE) for the first time. Soft errors in the on-chip memory (OCM), D-Cache, Register and BRAM blocks were investigated. The obtained device cross sections are almost in the range of 10−13 cm2 to 10−11 cm2 for the blocks. The results demonstrate that electron fluence per pulse and the corresponding prompt dose rates have no influence on the soft errors in 28 nm SoC. The discrepancy was analyzed between proton and electron inducing soft errors in D-Cache and BRAM blocks, too. The secondary electron is considered as the dominant reason for soft errors caused by 12 MeV electron in 28 nm SoC. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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13. Motional characteristic and impact of fiber particles in the impeller of a centrifugal pump.
- Author
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Zhang, Qihua, Xie, Zhiang, Kang, Shun, Zhong, Chengcheng, Zhang, Weidong, and Yan, Zhaoxu
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CENTRIFUGAL pumps , *IMPELLERS , *FIBERS , *GRANULAR flow , *PARTICLE motion , *POLYCARBONATES - Abstract
A centrifugal pump whose open impeller was made of polycarbonate was adopted to explore the influence of different concentrations of slender fiber particles on the external characteristics of the pump and to obtain the motional characteristics of the particles in the channels of the impeller. The external characteristics of the pump were used to determine the performance of the pump. A high-speed photographic system was used to analyze the motion of fiber particles in the channels of the impeller. Changes in the head and efficiency of the pump and changes in the distribution of fiber particles in impeller channels were obtained under different concentrations of fiber particles and different flow rates of fiber suspensions. The head associated with the transport of a fiber suspension whose mass concentration of fiber particles was 0.15% and the head associated with the transport of a fiber suspension whose mass concentration of fiber particles was 0.30% did not differ greatly from the head associated with the transport of clean water. However, compared to the transport of clean water, the transport of the fiber suspensions improved the efficiency of the pump. When the pump transported the fiber suspension whose mass concentration of fiber particles was 0.30%, on average, the efficiency of the pump increased by 8.49%. When the flow rates of the fiber suspensions increased, the uniformity of the distribution of the particles increased. When entering the impeller, a small number of fiber particles showed rotating and flapping motions. However, the motions gradually disappeared as the particles left the impeller. At a constant radius (i.e., 75% and 95% radius, respectively), the velocity profile increased gradually when the mass concentration of fiber particles increased from 0.1% to 0.15%. It is manifest that fiber suspension undergoes less flow loss as the mass concentration of fiber particles increases. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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14. Event-triggered state estimation for time-delayed complex networks with gain variations based on partial nodes.
- Author
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Hou, Nan, Dong, Hongli, Zhang, Weidong, Liu, Yurong, and Alsaadi, Fuad E.
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STOCHASTIC analysis , *GAUSSIAN distribution , *BINOMIAL distribution , *RANDOM variables , *ESTIMATION theory - Abstract
This paper designs the event-triggered non-fragile state estimator for a class of time-delayed complex networks with randomly occurring sensor saturations (ROSSs) and estimator gain variations on the basis of measurements from partial nodes. Both the time-varying state delays and the stochastic disturbances are considered in the network model. A Bernoulli-distributed white sequence is utilized to reflect the phenomenon of ROSSs. Two sequences of Gaussian distributed random variables combined with the multiplicative norm-bounded uncertainties are used to characterize the randomly occurring gain variations in the estimators. An event generator function is employed to regulate the transmission of data from the sensor to the estimator. The aim of this paper is to design an exponentially ultimately bounded state estimator in mean square through measurement outputs from a partial of network nodes under the event-triggered mechanism. With the help of Lyapunov-Krasovskii functional and stochastic analysis techniques, sufficient conditions are acquired for the existence of the desired state estimator which ensures that the estimation error dynamics is exponentially ultimately bounded in mean square, and then the estimator gain matrices can be computed via the software Matlab. A simulation example is provided to demonstrate the effectiveness of the proposed state estimation method. [ABSTRACT FROM AUTHOR]
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- 2018
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15. Age at menarche and its association with blood pressure in adult women of developing countries: a systematic review and meta-analysis.
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Wang, Gaili, Shao, Weihao, Chen, Xiaorui, Zheng, Caifang, Zhang, Bowen, and Zhang, Weidong
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RANDOM effects model , *BLOOD pressure , *MENARCHE , *AGE , *OLDER women ,DEVELOPING countries ,DEVELOPED countries - Abstract
Evidence about the effect of age at menarche (AAM) on blood pressure (BP) has largely been drawn from studies in developed countries. Studies in developing countries are expanding recently but have not been summarised. To systematically explore the association between AAM and BP and the potential modifiers in developing countries. We searched PubMed, Embase, and Web of Science for publications until March 2022. A random-effects model was used to calculate the pooled relative risk (RR) with 95% confidence interval (CI). Twenty studies were eligible. In studies with participants' mean age at BP assessment <55 years, women in the oldest group as compared with the middle or the youngest group of AAM had a higher risk of hypertension in those studies without adjustment for confounders (RR 1.79, 95% CI 1.41–2.28, I2=97.0%), those with adjustment for confounders excluding adiposity (1.25,1.04–1.51, I2=84.8%), and those with adjustment for confounders including adiposity (1.38,1.03–1.86, I2=91.8%). In studies with participants' mean age at BP assessment ≥55 years, no significant differences were found for studies without adjustment for confounders (RR 1.07, 95% CI 0.78–1.47, I2=90.3%), studies with adjustment for confounders excluding adiposity (0.85, 0.78–0.92, I2=12.3%), or studies with adjustment for confounders including adiposity (0.95, 0.80–1.11, I2=45.5%). A similar association was observed between AAM and baseline systolic BP and diabolic BP. Late menarche was associated with a higher risk of BP and this association was modified by age and adiposity in developing countries. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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16. MLP-based adaptive neural control of nonlinear time-delay systems with the unknown hysteresis.
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Zhang, Guoqing, Sun, Zhijian, Zhang, Weidong, and Qiao, Lei
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TIME delay systems , *NONLINEAR control theory , *LYAPUNOV functions , *CLOSED loop systems , *HYSTERESIS - Abstract
In this note, the authors study the tracking problem for uncertain nonlinear time-delay systems with unknown non-smooth hysteresis described by the generalised Prandtl–Ishlinskii (P-I) model. A minimal learning parameters (MLP)-based adaptive neural algorithm is developed by fusion of the Lyapunov–Krasovskii functional, dynamic surface control technique and MLP approach without constructing a hysteresis inverse. Unlike the existing results, the main innovation can be summarised as that the proposed algorithm requires less knowledge of the plant and independent of the P-I hysteresis operator, i.e. the hysteresis effect is unknown for the control design. Thus, the outstanding advantage of the corresponding scheme is that the control law is with a concise form and easy to implement in practice due to less computational burden. The proposed controller guarantees that the tracking error converges to a small neighbourhood of zero and all states of the closed-loop system are stabilised. A simulation example demonstrates the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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17. Optimal disturbance rejection controller design for integrating processes with dead time based on algebraic theory.
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Zhang, Wei, Wang, Yagang, and Zhang, Weidong
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CONTROL theory (Engineering) , *H2 control , *DEGREES of freedom , *ROBUST control , *STABILITY theory , *QUANTITATIVE research - Abstract
In this paper, an H2optimal input-load disturbance rejection (ILDR) controller for integrating processes with dead time is proposed based on the internal model control principle. The main contribution of this work is that the optimal solution under ILDR criterion for integrating processes with dead time and input constant disturbances has been derived based on algebraic theory. To further improve the performance for both set-point tracking and input disturbance rejection, a two-degree-of-freedom (TDOF) control design method has also been developed. Compared with previous advanced control methods, the proposed design method has three main advantages. First, the optimal ILDR controller is derived systematically on the basis of algebraic theory. The designed controller is given in an analytical form. Second, a simple tune principle is developed. The set-point tracking performance specification and robustness stability specification can be quantitatively achieved by monotonously tuning the performance degree in the designed controller. Finally, both optimal set-point tracking performance and input disturbance rejection can be achieved by the proposed TDOF control structure. Numerical simulations are given to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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18. Robust adaptive tracking control of MIMO nonlinear systems in the presence of actuator hysteresis.
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Fu, Guiyuan, Ou, Linlin, and Zhang, Weidong
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ROBUST control , *TRACKING control systems , *MIMO systems , *NONLINEAR systems , *ACTUATORS , *HYSTERESIS , *MATHEMATICAL bounds , *LOWPASS electric filters - Abstract
Adaptive tracking control of a class of MIMO nonlinear system preceded by unknown hysteresis is investigated. Based on dynamic surface control, an adaptive robust control law is developed and compensators are designed to mitigate the influences of both the unknown bounded external uncertainties and the unknown Prandtl–Islinskii hysteresis. By adopting the low-pass filters, the explosion of complexity caused by tedious computation of the time derivatives of the virtual control laws is overcome. With the proposed control scheme, the closed-loop system is proved to be semi-globally ultimately bounded by the Lyapunov stability theory, and the output of the controlled system can track the desired trajectories with an arbitrarily small error. Finally, numerical simulations are given to verify the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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19. Dynamic quantised feedback stabilisation of discrete-time linear system with white noise input.
- Author
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Ji, Mingming, He, Xing, and Zhang, Weidong
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DYNAMICAL systems , *FEEDBACK control systems , *DISCRETE-time systems , *LINEAR systems , *WHITE noise - Abstract
In this paper, we mainly focus on the problem of quantised feedback stabilisation of a stochastic discrete-time linear system with white noise input. The dynamic quantiser is used here. The stability of the system under state quantisation and input quantisation is analysed in detail, respectively. Both the convergence of the state's mean and the boundedness of the state's covariance matrix norm should be considered when analysing its stability. It is shown that for the two situations of the state quantisation and the input quantisation, if the system without noise input can be stabilised by a linear feedback law, it must be stabilised by the dynamic quantised feedback control policy. The sufficient conditions that the dynamic quantiser should satisfy are given. Using the results obtained in this paper, one can test whether the stochastic system is stabilisable or not. Numerical examples are given to show the effectiveness of the results. [ABSTRACT FROM PUBLISHER]
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- 2015
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20. A fault detection observer design for LPV systems in finite frequency domain.
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Chen, Jianliang, Cao, Yong-Yan, and Zhang, Weidong
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LONG-period variables , *FINITE element method , *FREQUENCY-domain analysis , *DEBUGGING , *PARAMETER estimation , *LINEAR statistical models - Abstract
This paper addresses the fault detection observer design problem for linear parameter-varying systems. Two finite frequency performance indexes are introduced to measure the fault sensitivity and the disturbance robustness. First, theH−index fault sensitivity condition in finite frequency domain is obtained by generalised Kalman–Yakubovich–Popov lemma and new linearisation techniques. Then, with the aid of Kalman–Yakubovich–Popov lemma and projection lemma, the stability and robustness conditions are derived. It turns out that the non-convexity problem which is caused by dealing with the above three conditions can be translated into a bilinear matrix inequality optimisation problem by increasing the dimensions of slack variable matrix. An iterative linear matrix inequality algorithm is proposed to get the solution. The effectiveness of the filter is shown via three numerical examples. [ABSTRACT FROM PUBLISHER]
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- 2015
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21. The correlation between body mass index and prostatic-related parameters in men 40 years or older in Zhengzhou.
- Author
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Yue, Limin, Ge, Yongchao, Wang, Tao, Ge, Mengying, Zhang, Chengda, and Zhang, Weidong
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BODY mass index , *PROSTATE-specific antigen - Abstract
Purpose: To understand the relationship between body mass index (BMI), age, prostate volume (PV), prostate-specific antigen (PSA), International Prostate Symptom Score (IPSS) and quality of life (QoL) in Zhengzhou.Materials and Methods: In the cross-sectional study, men living in Zhengzhou were invited to participate in this study. Men who were 40 years or older were subjected to the IPSS and related examination. A total of 1360 participants were included. Body mass index < 18.5 kg/m2 was determined as underweight, 18.5-24.99 kg/m2 normal, 25-29.99 kg/m2 overweight, and ≥30 kg/m2 obese.Results: The mean BMI was 24.92 ± 3.37 kg/m2. The mean PSA was 1.06 ± 0.85 ng/mL. The mean PV was 20.10 ± 9.96 mL. The mean age was 62.72 ± 11.03 years. The mean IPSS was 5.87 ± 3.48 scores. The mean QoL was 2.33 ± 1.28 scores. PSA showed a significant tendency to decrease with increasing BMI (r = -0.061, p = 0.018, ptrend = 0.037). The same with age (r = -0.109, p < .001; ptrend = .045). But the result suggested that both IPSS and QoL were positively correlated with BMI (r = 0.120, p < .001, ptrend < .001; r = 0.083, p = .001, ptrend = .021, respectively). PV increased with increasing BMI (r = 0.110, p < .001, ptrend = 0.045 ).Conclusions: Age, PSA decreased with increasing BMI. But larger PV, IPSS, and QoL were associated with higher BMI. [ABSTRACT FROM AUTHOR]- Published
- 2020
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22. Gain scheduling consensus of multi-agent systems subject to actuator saturation.
- Author
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Chu, Hongjun, Chen, Jianliang, Wei, Qinglai, and Zhang, Weidong
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INVARIANT sets , *MULTIAGENT systems , *ACTUATORS , *PARAMETRIC equations , *COMPUTER simulation - Abstract
This paper presents a gain scheduling approach for achieving the consensus tracking of multi-agent systems with actuator saturation. We first construct a series of nesting ellipsoid invariant sets associated with consensus errors. When the consensus errors stay between the two ellipsoid invariant sets, the feedback gains keep constant, but when the consensus errors enter into the smaller ellipsoid invariant set, the feedback gains abruptly become larger. By combining this gain scheduling technique and the parametric Lyapunov equations, we, respectively, design state and output feedback gain scheduling protocols. Their main advantage, in comparison with the fixed case, is that the convergence rate of consensus tracking can be enhanced by scheduling the gain parameters. Numerical simulations verify the effectiveness of theoretical analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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23. Metabolomics analysis of human plasma metabolites reveals the age- and sex-specific associations.
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Wang, Yixiao, Wang, Guangshu, Jing, Ru'nan, Hu, Ting, Likhodii, Sergei, Sun, Guang, Randell, Edward, Jia, Guihua, Yu, Tianmiao, and Zhang, Weidong
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ELECTROSPRAY ionization mass spectrometry , *METABOLOMICS , *BLOOD plasma , *METABOLITES , *BODY mass index - Abstract
Objectives: The objective of this study was the investigation of age- and sex-associations in a set of blood plasma metabolites in healthy male and female subjects. Methods: A comparison study design with male and female subjects of various ages was used. Metabolic profiling was performed using electrospray ionization tandem mass spectrometry that yielded 186 metabolite concentrations for each study participant. The key age-related metabolites were identified using an integrative analysis of absolute concentrations, metabolite ratios and the differential correlation of pairwise metabolite concentrations. All of the age-associated metabolites were adjusted prior to the analysis to account for differences in Body Mass Index (BMI). Results: A total of 236 plasma samples from 140 female and 96 male subjects aged 20 to 82 years-old were collected and analyzed in the study. 13 and 14 age-associated metabolites (|r| > 0.33 and p < 6.6×10−5), 438 and 337 age-associated metabolite ratios (|r| > 0.37 and p < 3.5×10−6), and 5 and 10 core metabolites were discovered in the female and male groups, respectively. 80% of the metabolites displaying associations with age belonged to sphingolipids and phosphatidylcholines, and the two sexes shared less than 50% of the age-associated metabolites. Conclusion: The study found that changes in metabolite concentrations, metabolite ratios and differential correlations were age and sex-specific. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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24. Adaptive output-feedback formation control for underactuated surface vessels.
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Lu, Yu, Zhang, Guoqing, Qiao, Lei, and Zhang, Weidong
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ADAPTIVE control systems , *CLOSED loop systems , *PSYCHOLOGICAL feedback - Abstract
This paper investigates the leader–follower formation problem of underactuated surface vessels. Velocities of both leader and follower vessels are unavailable. Model uncertainties and ocean disturbances are also considered. By incorporating adaptive control, neural networks (NNs), the high-gain observer (HGO) and the minimal learning parameter (MLP) algorithm in the backstepping procedure, a novel adaptive output-feedback formation control scheme is developed. We show that formation errors can be guaranteed to be semiglobally uniformly ultimately bounded (SGUUB) with the proposed controller. Compared with existing methods, the formation can be achieved only with position and yaw angle of both leader and follower. Meanwhile, the developed scheme can enhance the robustness of the closed-loop system with less computational effort, where only two online parameters need to be tuned. Simulation and comparison results are provided to illustrate the effectiveness of theoretical results. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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25. Optimal control of non-minimum phase integrating processes with time delay using disturbance observer-based control scheme.
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Zhang, Wei, Wang, Yagang, Yin, Zhong, Wang, Yongxiong, and Zhang, Weidong
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OPTIMAL control theory , *TIME delay systems , *COMPUTER simulation , *PID controllers , *CLOSED loop systems - Abstract
A systematical design method of optimal control for non-minimum phase integrating processes with time delay using disturbance observer-based (DOB) control scheme is presented. All stabilising controllers and the filter of DOBs for integrating plants are developed. Then the optimal set-point tracking controller and the optimal filter of DOB are systematically derived by minimising the H2 norm performance specifications. The proposed design method has three main advantages. First, the design procedure is systematical and simple. Specified weight functions are chosen for step inputs and inputs similar to steps. The designed set-point tracking controller and the filter of DOB are given in analytical forms. Second, the designed set-point tracking controller and the filter of the DOB are optimal. They are derived from minimising the performance indexes of set-point tracking and input load disturbance rejection (ILDR). Finally, the set-point tracking performance specification and ILDR specification can be quantitatively achieved by conveniently tuning the adjustable parameters. Numerical simulations are given to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
26. Performance recovery of a class of uncertain non-affine systems with unmodelled dynamics: an indirect dynamic inversion method.
- Author
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Yi, Bowen, Lin, Shuyi, Yang, Bo, and Zhang, Weidong
- Subjects
- *
FEEDBACK control systems , *PERFORMANCE evaluation , *APPROXIMATION algorithms , *ROBUST control , *MATHEMATICAL proofs - Abstract
This paper presents an output feedback indirect dynamic inversion (IDI) approach for a class of uncertain nonaffine systems with input unmodelled dynamics. Compared with previous approaches to achieve performance recovery, the proposed method aims at dealing with a broader class of nonaffine-in-control systems with triangular structure. An IDI state feedback law is designed first, in which less knowledge of the model plant is needed compared to earlier approximate dynamic inversion methods, thus yielding more robust performance. After that, an extended high-gain observer is designed to accomplish the task with output feedback. Finally, we prove that the designed IDI controller is equivalent to an adaptive proportional-integral (PI) controller, with respect to both time response equivalence and robustness equivalence. The conclusion implies that for the studied strict-feedback non-affine systems with unmodelled dynamics, there always exits a PI controller to stabilise the systems. The effectiveness and benefits of the designed approach are verified by three examples. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
27. An extended inner–outer factorisation algorithm based on the structure of a transfer function matrix inverse.
- Author
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Zhang, Wei, Zhao, Chunhui, He, Xing, and Zhang, Weidong
- Subjects
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FACTORIZATION , *QUANTUM mechanics , *TRANSFER functions , *COMPUTER simulation , *MIMO systems , *MATRICES (Mathematics) - Abstract
In this paper, the structure feature of the inverse of a multi-input/multi-output square transfer function matrix is explored. Instead of complicated advanced mathematical tools, we only use basic results of complex analysis in the analysing procedure. By employing the Laurent expression, an elegant structure form of the expansion is obtained for the transfer function matrix inverse. This expansion form is the key of deriving an analytical solution to the inner–outer factorisation for both stable plants and unstable plants. Different from other computation algorithm, the obtained inner–outer factorisation is given in an analytical form. The solution is exact and without approximation. Numerical examples are provided to verify the correctness of the obtained results. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
28. Multivariable disturbance observer-based H 2 analytical decoupling control design for multivariable systems.
- Author
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Zhang, Wei, Wang, Yagang, Liu, Yurong, and Zhang, Weidong
- Subjects
- *
OBSERVABILITY (Control theory) , *MULTIVARIABLE control systems , *MATHEMATICAL decoupling , *MIMO systems , *TIME delay systems , *ROBUST control - Abstract
In this paper, an H2analytical decoupling control scheme with multivariable disturbance observer for both stable and unstable multi-input/multi-output (MIMO) systems with multiple time delays is proposed. Compared with conventional control strategies, the main merit is that the proposed control scheme can improve the system performances effectively when the MIMO processes with severe model mismatches and strong external disturbances. Besides, the design method has three additional advantages. First, the derived controller and observer are given in analytical forms, the design procedure is simple. Second, the orders of the designed controller and observer are low, they can be implemented easily in practice. Finally, the performance and robustness can be adjusted easily by tuning the parameters in the designed controller and observer. It is useful for practical application. Simulations are provided to illustrate the effectiveness of the proposed control scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
29. On the pole of non-square transfer function matrix Moore–Penrose pseudo-inverses.
- Author
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Zhang, Wei, Ou, Linlin, He, Xing, and Zhang, Weidong
- Subjects
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TRANSFER functions , *GENERALIZED inverses of linear operators , *POLYNOMIALS , *MATHEMATICS theorems , *NUMERICAL analysis - Abstract
An essential step in many controller design approaches is computing the inverse of the plant. For a square plant, its inverse is stable if the plant is minimum phase (MP). Nevertheless, this conclusion does not hold for a non-square plant. In this paper, the pole feature of the Moore–Penrose pseudo-inverse of a non-square transfer function matrix is analysed. Instead of complicated advanced mathematical tools, only basic results of polynomial theory and the Binet–Cauchy theorem are used in the analysing procedure. The condition for testing the stability of the Moore–Penrose pseudo-inverse of an MP non-square transfer function matrix is given. This condition implies that the Moore–Penrose pseudo-inverse of a non-square transfer function matrix cannot be directly used as the optimal controller. Numerical examples are provided to illustrate the correctness of the condition. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
30. Pd-Catalyzed Cross-Coupling of Acyl Chlorides with In Situ–Generated Alkynylzinc Derivatives for the Synthesis of Ynones.
- Author
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Yuan, Hu, Shen, Yunheng, Yu, Shichong, Shan, Lei, Sun, Qingyan, and Zhang, Weidong
- Subjects
- *
CHEMICAL synthesis , *CHEMISTRY periodicals , *CATALYSIS , *ACYL chlorides , *SOLVENTS - Abstract
A mild and operationally simple procedure by Pd-catalyzed cross-coupling of acyl chlorides with in situ–generated alkynylzinc derivatives was developed, giving the corresponding ynones in good yields. Supplementary materials are available for this article. Go to the publisher's online edition ofSynthetic Communications®full experimental and spectral details. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
31. TCR Sign Variation of Surface Micromachined Polysilicon Resistor under Joule Self-Heating.
- Author
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Ma, Hongyu, Wang, Lei, Song, Jing, Zhang, Weidong, and Ding, Enjie
- Subjects
- *
TEMPERATURE coefficient of electric resistance , *POLYCRYSTALLINE silicon , *RESISTANCE heating , *MICROELECTROMECHANICAL systems , *NEGATIVE temperature - Abstract
This work reports the sign variation of temperature coefficient of surface micromachined polysilicon resistor due to Joule self-heating effect. It was found that the sign of temperature coefficient of polysilicon resistor with initial negative temperature coefficient value varies two times from negative to positive and then from positive to negative with the consumed power increasing, while the sign of the temperature coefficient of polysilicon resistor with initial positive value only changes once to negative. The experiment results indicate that much more attention should be paid to the temperature coefficient of polysilicon resistor for the surface micromachined electrothermal polysilicon devices. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
32. Metabolomics in serum of ovariectomised rats and those exposed to 17β-oestradiol and genistein.
- Author
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Zhu, Xiaoyan, Liu, Xinru, He, Ping, Cao, Buqing, Lv, Yonghai, Zhang, Weidong, and Ni, Xin
- Subjects
- *
SERUM , *GENISTEIN , *LABORATORY rats , *METABOLITES , *LIQUID chromatography , *TIME-of-flight mass spectrometry , *FRAGMENTATION reactions , *PHYSIOLOGY - Abstract
Objective. Metabolites profiling provides global insights in characterisations and interactions of metabolites under specific physiological or pathologic states. The aim of this study was to examine serum metabolic changes in bilateral ovariectomised (OVX) rats and those exposed to 17β-oestradiol (E2, 30 μg/kg bw, sc.) or genistein (50 μg/kg bw, sc.) for 12 weeks. Methods. Serum samples were detected by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-q-TOF-MS). Significant variables were found by the orthogonal partial least-squares analysis and identified by matching their tandem MS fragmentation patterns with reference standards. Results. There were 54 variables changed in OVX group compared with sham group. Genistein might induce more intensive changes of metabolites than E2 in OVX rats. Among the 54 significant variables of OVX group, 8 and 20 were found to be affected by E2 and genistein, respectively. Finally, four of them were identified as arachidonic acid (AA), eicosapentaenoic acid (EPA), ergocalciferol and cholecalciferol. Both E2 and genistein could reverse levels of AA, EPA and ergocalciferol to sham levels. Only genistein treatment could reverse the level of cholecalciferol. Conclusions. This study provided a serum profile of ovary dysfunction and showed some similarities and differences between E2 and genistein treatments of the OVX model. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
33. Proteomic and Tissue Array Profiling Identifies Elevated Hypoxia-Regulated Proteins in Pancreatic Ductal Adenocarcinoma.
- Author
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Cui, Yazhou, Zhang, Denglu, Jia, Qing, Li, Tianliang, Zhang, Weidong, and Han, Jinxiang
- Subjects
- *
CANCER diagnosis , *PANCREAS , *CEREBRAL anoxia , *MONOSACCHARIDES ,DIGESTIVE organ cancer - Abstract
We identified a group of hypoxia-regulated proteins upregulated in microdissected pancreatic cancer nests compared with normal pancreatic ducts. Immunohistochemical study further validated that pancreatic cancers had significantly higher expression levels of glucose-regulated protein 78, macrophage migration inhibitory factor and annexin A5 than normal pancreas tissues, these protein biomarkers also demonstrated high receiver operating characteristic curves in discriminating pancreatic cancers from normal pancreas. In conclusion, our study indicated a link between pancreatic cancer and hypoxia-regulated proteins. Glucose-regulated protein 78, macrophage migration inhibitory factor and annexin A5 might be promising targets for pancreatic cancer diagnosis and therapy. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
34. Quality Evaluation of Rhodiola crenulata: Quantitative and Qualitative Analysis of Ten Main Components by HPLC.
- Author
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Huang, Hao, Liang, Mingjin, Jiang, Peng, Li, Yongli, Zhang, Weidong, and Gong, Qianfeng
- Subjects
- *
HIGH performance liquid chromatography , *BIOACTIVE compounds , *FLAVONOIDS , *PLANT pigments , *CHINESE medicine - Abstract
A high performance liquid chromatographic method has been performed for the simultaneous identification and quantification of ten bioactive components in three botanical materials of Rhodiola genus (R. crenulata, R. sachliensis and R. dumulos). Eight samples of Rhodiola genus prepared from three different botanical materials were investigated by the proposed method, and the variance was revealed by the calculated results of these contents and similarity values for ten main flavonoids. The proposed method is simple, effective, and suitable for the evaluation of this traditional Chinese medicine. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
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