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Search Results: 1 - 10 of 42559 matches for " XU Chuanxiu "
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Perfectly Matched Layer for an Elastic Parabolic Equation Model in Ocean Acoustics Perfectly Matched Layer for an Elastic Parabolic Equation Model in Ocean Acoustics
XU Chuanxiu,ZHANG Haigang,PIAO Shengchun,YANG Shi'e,SUN Sipeng,TANG Jun
- , 2017,
Abstract: The perfectly matched layer(PML) is an effective technique for truncating unbounded domains with minimal spurious reflections. A fluid parabolic equation(PE) model applying PML technique was previously used to analyze the sound propagation problem in a range-dependent waveguide(Lu and Zhu, 2007). However, Lu and Zhu only considered a standard fluid PE to demonstrate the capability of the PML and did not take improved one-way models into consideration. They applied a [1/1] Padé approximant to the parabolic equation. The higher-order PEs are more accurate than standard ones when a very large angle propagation is considered. As for range-dependent problems, the techniques to handle the vertical interface between adjacent regions are mainly energy conserving and single-scattering. In this paper, the PML technique is generalized to the higher order elastic PE, as is to the higher order fluid PE. The correction of energy conserving is used in range-dependent waveguides. Simulation is made in both acoustic cases and seismo-acoustic cases. Range-independent and range-dependent waveguides are both adopted to test the accuracy and efficiency of this method. The numerical results illustrate that a PML is much more effective than an artificial absorbing layer(ABL) both in acoustic and seismo-acoustic sound propagation modeling
Corticotropin-Releasing Factor Facilitates Epileptiform Activity in the Entorhinal Cortex: Roles of CRF2 Receptors and PKA Pathway
Lalitha Kurada, Chuanxiu Yang, Saobo Lei
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0088109
Abstract: Whereas corticotropin-releasing factor (CRF) has been considered as the most potent epileptogenic neuropeptide in the brain, its action site and underlying mechanisms in epilepsy have not been determined. Here, we found that the entorhinal cortex (EC) expresses high level of CRF and CRF2 receptors without expression of CRF1 receptors. Bath application of CRF concentration-dependently increased the frequency of picrotoxin (PTX)-induced epileptiform activity recorded from layer III of the EC in entorhinal slices although CRF alone did not elicit epileptiform activity. CRF facilitated the induction of epileptiform activity in the presence of subthreshold concentration of PTX which normally would not elicit epileptiform activity. Bath application of the inhibitor for CRF-binding proteins, CRF6-33, also increased the frequency of PTX-induced epileptiform activity suggesting that endogenously released CRF is involved in epileptogenesis. CRF-induced facilitation of epileptiform activity was mediated via CRF2 receptors because pharmacological antagonism and knockout of CRF2 receptors blocked the facilitatory effects of CRF on epileptiform activity. Application of the adenylyl cyclase (AC) inhibitors blocked CRF-induced facilitation of epileptiform activity and elevation of intracellular cyclic AMP (cAMP) level by application of the AC activators or phosphodiesterase inhibitor increased the frequency of PTX-induced epileptiform activity, demonstrating that CRF-induced increases in epileptiform activity are mediated by an increase in intracellular cAMP. However, application of selective protein kinase A (PKA) inhibitors reduced, not completely blocked CRF-induced enhancement of epileptiform activity suggesting that PKA is only partially required. Our results provide a novel cellular and molecular mechanism whereby CRF modulates epilepsy.
A Decision Problem of Hotels on Setting Online-Exclusive-Rooms in E-Commerce Age  [PDF]
Liang Xu, Xiaoyan Xu
Journal of Service Science and Management (JSSM) , 2014, DOI: 10.4236/jssm.2014.74029
Abstract:

Due to the rapid development of information technology, customers’ consumption pattern in hotel industry has dramatically changed, and many people book rooms through some professional online platforms. Hotel managers need to redesign their sale channel structures by incorporating online platforms, in order to increase profit. This paper focuses on a revenue maximization problem for a hotel which cooperates with an online platform. Two cooperating forms are investigated and compared. Specifically, one intuitive form is named complete sharing, in which all the hotel rooms are shared with the online platform for booking. The other form is named setting online-exclusive-rooms (OERs), in which the hotel set a fixed quantity of rooms for exclusively booking from the online platform. By building a loss queueing model, this paper finds some properties of the optimal quantity of OERs in the latter form. Factors affecting the selection and how they affect the selection are also investigated.

An Algorithm for Improving Throughput Guarantee of Topology-Transparent MAC Scheduling Strategy  [PDF]
Chaonong Xu
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.210096
Abstract: Topology-transparent MAC scheduling strategies nowadays are all based on combinatorial design. To get throughput guarantee, a cover-free set is output as scheduling strategy of network. In this paper, we aim to modify the cover-free set so that better throughput can be guaranteed. At the first step, the redundant slot of the cover-free set is proposed and found to have negative influence on the minimal guaranteed throughput. Second, we prove that any subset of a cover-free set is still a cover-free set after its redundant slots were squashed out. Our algorithm chooses the subset which has the maximal number of redundant slots, squashes all of its redundant slots, and then designates it as the network scheduling strategy. Therefore, better through- put can be guaranteed if the squashed subset is adopted as network scheduling strategy. For any topology- transparent node scheduling strategy, both the increased minimal throughput and decreased maximal transmission delay can be gotten by just using our algorithm as an extra accessory.
Experimental and Numerical Study of the Effect of Surround Protection Technique on the Strain Measurement for Offshore Jacket Platform  [PDF]
Yongjun Xu
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.35056
Abstract: For strain measurement on offshore jacket platform in deep water, waterproof of strain foil is always an important issue, especially, due to the high pressure in deep water. The waterproof is difficult in two places, one is between the matrix structure and the protection structure, and another is between the lead wires and the protection structure. The surround protection technique discussed in this paper is conventional and ideal, and can be operative for a long time, up to five years. In this method, a metal case and tube is added on the local position, which increases the local rigidity, but the effect on the measurement of strain is not well studied. In this paper, the effect of the surround protection technique on the strain measurement is studied by using numerical and experimental methods, and the results show that the measurement error is well in the range permitted by engineering practice.
Editorial: Special Section on Reinforcement Learning and Approximate Dynamic Programming  [PDF]
Xin Xu
Journal of Intelligent Learning Systems and Applications (JILSA) , 2010, DOI: 10.4236/jilsa.2010.22008
Abstract: .
A Kind of Potential Practical Sensors of Metamaterial in Electromagnetic Flaw Nondestructive Testing  [PDF]
Zhanxian Xu
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.37090
Abstract: We present a new kind of method of electromagnetic flaw nondestructive testing with coating of metamaterials and simulation near electromagnetic field property for test crack. The simulation of improving a Nondestructive testing (NDT) probe electromagnetic radiant property by Metamatrials (MMs) covering a tiny current element is investigated and analyzed using Ansoft HFSS based on finite element method (FEM), which permittivity and permeability are negative. Electromagnetic model: Ideal MMs ball shell with inner radius of 1 mm and outer radius variation, and the shell’s relative permittivity and relative permeability are all –3.0, dielectric loss tangent and magnetic loss tangent are all 0.1; and exciting current element length is with 0.3 mm, diameter 0.2 mm, value 1 mA at frequency 10 GHz; and simulation is with radiation boundary conditions. The simulating near electromagnetic field variety with ratio of inner radius and out radius, and so near or local field of MMs sensor on a surface crack, as well as comparing near field value of sensor with coating common material are finished. Results can be seen that MMs film sensor near electromagnetic field and radiation properties are obviously better than other two kinds of structures without coating medium and coating with common medium, and Metamaterial may be opened out some new kinds of sensors in electromagnetic flaw nondestructive testing for potential practical applications in future.
Rethinking the China-US Balance of Trade: 1990-2005  [PDF]
Xiaoping Xu
iBusiness (IB) , 2012, DOI: 10.4236/ib.2012.41006
Abstract: Since 1993, American trade deficit with China is expanding and the gap is becoming increasingly bigger. The widening bilateral trade imbalance has caused growing concerns. This paper, by using empirical method and adjusting the data of trade from 1989 to 2005, finds that the causes of the imbalance of China-US trade are as follows: 1) the imbalance of domestic demands of US; 2) the adjustment of American economic structure, and 3) the growing of multinational enterprises. The paper also finds that the imbalance of China-US trade is not as big as it was reported by US; the imbalance of China-US trade is an inevitable result of economic development, and the trade deficit does not necessarily mean a loss of profit. In fact, American investors and consumers have greatly benefited from China-US trade.
Application Study on Multi-Vary Analysis  [PDF]
Xiaomin Xu
Modern Mechanical Engineering (MME) , 2013, DOI: 10.4236/mme.2013.31005
Abstract:

In this article, we studied the bearings made by one company in Shanghai. Through statistical process controlling the quality characteristic of bearings’ diameters and multi-vary analysis is applied to find the key variation factors which have an influence on the quality characteristic of the bearings, the quality level of the bearings of this company is improved.

DNA Circuit System and Charge Transfer Mechanism  [PDF]
Kunming Xu
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.510B077
Abstract:

Based on the accurate identification of chemical structures as electric elements, we described charge transport mechanism in a DNA molecule by a stepwiseLCoscillatory circuitry, in which every base pair is a capacitor, every phosphate bridge is an inductor, and every deoxyribose is a charge router. The circuit model agrees with established experimental evidence that has supported super-exchange and hopping mechanisms so far. This alternative charge transport mechanism through both strands of DNA matches the fidelity and reliability of its chemical structure.

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