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Search Results: 1 - 10 of 123656 matches for " Nan Wang "
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Adaptive Tracking Control of an Uncertain Nonholonomic Robot  [PDF]
Nan Hu, Chaoli Wang
Intelligent Control and Automation (ICA) , 2011, DOI: 10.4236/ica.2011.24045
Abstract: In this paper, a new controller is proposed by using backstepping method for the trajectory tracking problem of nonholonomic dynamic mobile robots with nonholonomic constraints under the condition that there is a distance between the mass center and the geometrical center and the distance is unknown. And an adaptive feedback controller is also proposed for the case that some kinematic parameters and dynamic parameters are uncertain. The asymptotical stability of the control system is proved with Lyapunov stability theory. The simulation results show the effectiveness of the proposed controller. The comparison with the previous methods is made to show the effectiveness of the method in this article.
A Note on the Defensive Orientation of the Renminbi Exchange Rate Policy  [PDF]
Wang Jinbin, Li Nan
Chinese Studies (ChnStd) , 2014, DOI: 10.4236/chnstd.2014.32009
Abstract: History shows that the United States has constantly been the winner in wars of exchange rate since U.S. dollar became the leading international currency. Likewise, the ongoing exchange rate war is bound to increase the costs of maintaining the existing paradigm of international division of labor (IDL henceforth) for emerging economies. In view of the rigid paradigm of IDL and dollar-dominated international monetary system, the defensive tactics of the Renminbi exchange rate policy is in conformity with the modes of China’s economic growth and gradual reform, as well as in correspondence with the asymmetric international financial system and trading system. Therefore, using the defensive tactics to reduce the costs of maintaining the existing paradigm of IDL will continue to be the basic policy for RMB exchange rate management in the next few years.
A new boosting algorithm based on dual averaging scheme
Nan Wang
Computer Science , 2015,
Abstract: The fields of machine learning and mathematical optimization increasingly intertwined. The special topic on supervised learning and convex optimization examines this interplay. The training part of most supervised learning algorithms can usually be reduced to an optimization problem that minimizes a loss between model predictions and training data. While most optimization techniques focus on accuracy and speed of convergence, the qualities of good optimization algorithm from the machine learning perspective can be quite different since machine learning is more than fitting the data. Better optimization algorithms that minimize the training loss can possibly give very poor generalization performance. In this paper, we examine a particular kind of machine learning algorithm, boosting, whose training process can be viewed as functional coordinate descent on the exponential loss. We study the relation between optimization techniques and machine learning by implementing a new boosting algorithm. DABoost, based on dual-averaging scheme and study its generalization performance. We show that DABoost, although slower in reducing the training error, in general enjoys a better generalization error than AdaBoost.
Antihypertensive Properties on Spontaneously Hypertensive Rats of Peptide Hydrolysates from Silkworm Pupae Protein  [PDF]
Wei Wang, Nan Wang, Yu Zhang
Food and Nutrition Sciences (FNS) , 2014, DOI: 10.4236/fns.2014.513131
Abstract:

Peptide hydrolysates of silkworm pupae protein with molecular weight of less than 5000 Da were prepared by ultrafiltration. The extracted peptide hydrolysates of silkworm pupae protein had inhibitory action on angiotensin-I-converting enzyme activity in vitro. The hydrolysates were orally administered to spontaneously hypertensive rats (SHR) in one period and long-term (four weeks). The results showed that the systolic blood pressure (SBP) of the treatment groups decreased in a dose-related manner. After one oral administration of silkworm protein hydrolysates with doses of 60, 20 and 5 mg/kg, the SBP of SHR decreased by 21.5, 13.8, and 9.0 mmHg in 1.5 h. After four weeks of the treatment in 80 mg/kg, the SBP decreased by 25 mmHg, with the antihypertensive activity close to 4 mg/kg of captopril; the SBP of the 40 mg/kg dose group also decreased by 17.5 mmHg. The peptide hydrolysate did not affect the SBP in normal, non-hypertensive rats in one period and long-term treatments. The acute toxicity research showed that the peptide hydrolysates were safe and without side effects. This research would be helpful in exploring the silkworm protein peptides as functional components for the antihypertension treatment.

Quasi-Rational Canonical Forms of a Matrix over a Number Field  [PDF]
Zhudeng Wang, Qing Wang, Nan Qin
Advances in Linear Algebra & Matrix Theory (ALAMT) , 2018, DOI: 10.4236/alamt.2018.81001
Abstract: A matrix is similar to Jordan canonical form over the complex field and the rational canonical form over a number field, respectively. In this paper, we further study the rational canonical form of a matrix over any number field. We firstly discuss the elementary divisors of a matrix over a number field. Then, we give the quasi-rational canonical forms of a matrix by combining Jordan and the rational canonical forms. Finally, we show that a matrix is similar to its quasi-rational canonical forms over a number field.
Application of Ant Colony Algorithm to the Analysis of Common Mode EMI Model of DC Motor  [PDF]
Jinfeng Liu, Xudong Wang, Jiang Nan
Energy and Power Engineering (EPE) , 2011, DOI: 10.4236/epe.2011.32013
Abstract: The Electromagnetic Compatibility (EMC) of direct current (DC) motor windings is a system model which is used to reflect the functional characters of the system in the whole EMC specified frequency (150 KHz ~ 30 MHz). For most motor designing process, it is always used to evaluate the inductance of windings in lower or working frequency; however, when analyzing the conducted interference, it is necessary to take some pa-rameters in high frequency into account in building up the EMC model, such as the noticeable capacitance distributed among the windings or between windings and shells. Past research neglected the common-mode current generated by the high frequency interference within motor bearings coupled with shells, since the parasitic capacitance of rotor core comes from armature windings supplied sufficient paths. In EMC model-ing process for DC motor problem, first, test the impedance of windings by experiments; then, generate the equivalent circuit with overall parameters. At present, it is a difficulty that how to choose the parameters. Most researchers preferred to adopt analytical calculation results, however, it could not reflect the essence of the model since it requires many simplification. Based on this point, this paper adopted ant colony algorithm (ACA) with positive feedback to intelligently search and globally optimize the parameters of equivalent cir-cuit. Simulation result showed that the impedance of equivalent circuit calculated by this algorithm was the same as experimental result in the whole EMC frequency. In order to further confirm the validity of ACA, PSPICE circuit simulation was implemented to simulate the spectrum of common mode Electromagnetic Interference (EMI) of equivalent circuit. The simulation result accords well with the experiment result re-ceived by EMI receiver. So it sufficiently demonstrated correctness of ACA in the analysis of high frequency equivalent circuit.
Impacts of oasis on the atmospheric hydrological cycle over the nearby desert  [PDF]
Qiang Zhang, Yuhe Nan, Sheng Wang
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.27084
Abstract: Using the data of “A field experiment on landatmosphere interaction over arid region in Northwest China” carried out in Dunhuang of Gansu Province from May to June 2000; Characteristics of the atmospheric humidity over desert and Gobi near oasis in the Northwest China Arid Region are analyzed. According to the difference of the characteristics in different wind directions, the impacts of oasis on atmospheric hydrological cycle over desert and Gobi near it are revealed. The relation of atmosphere inverse humidity and negative water vapor flux to wind direction and atmospheric stability is studied. It shows that distribution of the atmosphere inverse humidity is inconsistent with that of the negative water vapor flux; sometimes 1-hour-average value demonstrates the characteristic of counter-gradient transfer. And the diurnal variation of distribution of the counter-gradient transfer and the effect of atmospheric stability on the counter-gradient transfer are also given.
Research on Source Maintenance Key Technology of the Smart Substation  [PDF]
Wei Liang, Nan Wang, Zheng Wang, Tao Liu, Yunfei Mu
Journal of Power and Energy Engineering (JPEE) , 2014, DOI: 10.4236/jpee.2014.24034
Abstract: The source maintenance technology of the smart substation offers the base for the models, data and graphs sharing between the substation and the dispatch center. This paper researches on the conversion technology between SCD model in IEC 61850 Ed. 2 and the CIM model in IEC 61970. The substation provides SVG and SCD documents to the dispatch center, which includes primary equipment information and the network topology. The dispatch center’s automation system completes the conversion between the two models. This paper researches on the smart remote technology, which uses IEC 61850 as communication protocol. It can filter and restructure communication data based on the needs of different dispatch center. At the same time, it can provide quality control of communication link, to ensure that the important data be sent in real time.
Effect of Nitrogen Pressure on the Structure of Cr-N, Ta-N, Mo-N, and W-N Nanocrystals Synthesized by Arc Discharge
Longhai Shen,Nan Wang
Journal of Nanomaterials , 2011, DOI: 10.1155/2011/781935
Abstract: The effect of nitrogen pressure on the structure of Ta-N, Cr-N, Mo-N, and W-N nanocrystals formed in arc discharge process was investigated. At the nitrogen pressure of ?kPa, the pure cubic-phase TaN and CrN nanocrystals were formed, whereas pure cubic phase of Mo2N and W2N cannot be obtained. A little of metal Mo and a mass of metal W were mixed with the products of Mo2N and W2N, respectively. At the nitrogen pressure of ?kPa, subnitride Ta2N and Cr2N and metal Cr were gradually formed in the product; furthermore, the proportion of metal Mo and W increased in the product of Mo2N and W2N, respectively. It indicated that the low nitrogen pressure makes cubic mononitride formation favorable. We explain this experimental observation in terms of the evaporation rate of anode metal and the ionization of nitrogen. 1. Introduction Transition metal nitrides are well known for having a number of technologically interesting properties: abrasive resistance, reflectance, hardness, electrical conductivity, inertness and diffusion resistance [1, 2]. These outstanding properties make them as bulk or thin film materials applicable to various fields such as high-temperature structural ceramics, catalysts, solar control coatings, hard phases in steels, drill bit, tool coating, interconnects, and diffusion barriers in microelectronics as well as decorative coatings and jewellery [3]. Recently, the nitrides of tantalum and chromium and its homologues molybdenum and tungsten have attracted great research attention due to their special properties of extreme hardness, high metallic conductivity, good thermal conductivity, corrosion resistance, and high melting points, so they were extensively applied in mechanical, tribological and catalyst fields [4–13]. It is known that ultrafine particles possess unique characteristics that cannot be obtained for conventional bulk materials. With the aim of developing advance materials, a number of studies on the synthesis of ultrafine particles or nanosized materials have been carried out actively in metal, alloys, and ceramics [14]. There has been an increasing interest in the synthesis of TaN, CrN, Mo2N, and W2N nanocrystals recently [15–21]. Of course, these nitrides are the most difficult to form by direct reaction through transition metal with nitrogen. This is because they exhibit the lowest reactivity towards nitrogen, the lowest stability, and the narrowest regions of existence in the phase diagrams. In addition, N2 is very stable and inert due to having strong covalent bonds. Consequently, in order to enhance the diffusion of
Some Oscillation Results for Linear Hamiltonian Systems
Nan Wang,Fanwei Meng
Journal of Applied Mathematics , 2012, DOI: 10.1155/2012/942042
Abstract: The purpose of this paper is to develop a generalized matrix Riccati technique for the selfadjoint matrix Hamiltonian system =()
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