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Search Results: 1 - 10 of 42561 matches for " HuaBi Xu "
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Effects of high temperature annealing on the dislocation density and electrical properties of upgraded metallurgical grade multicrystalline silicon
HuaBi Xu,RuiJiang Hong,Hui Shen
Chinese Science Bulletin , 2011, DOI: 10.1007/s11434-010-4090-7
Abstract: High temperature annealing was performed on upgraded metallurgical grade multicrystalline silicon (UMG multi-Si) wafers with a purity of 99.999%. The samples were mechanically polished and chemically etched, and then the microstructures were observed by a scanning electron microscope (SEM). The minority carrier lifetime and resistivity of the samples were measured using microwave photoconductance decay and four-point probe techniques, respectively. The results show that the electrical properties of the samples decrease rather than increase as the annealing temperature increases, while the number of dislocations in bulk Si reduced or even disappeared after annealing for 6 hours at 1100–1400°C. It is considered that the structural microdefects induced by the high concentration of metal impurities (including interstitial or substitutional impurities and nanoscale precipitates) determine the minority carrier recombination activity and thus the electrical properties of UMG multi-Si wafers rather than dislocations in bulk Si.
Chern-Simons Theory of Fractional Quantum Hall Effect in (Pseudo) Massless Dirac Electrons
Huabi Zeng
Physics , 2011, DOI: 10.1142/S0217979211100606
Abstract: We derive the effective field theory from the microscopic Hamiltonian of interacting two-dimensional (pseudo) Dirac electrons by performing a statistic gauge transformation. The quantized Hall conductance are expected to be $\sigma_{xy}=\frac{e^2}{h}(2k-1)$ with $k$ is arbitrary integer. There are also topological excitations which have fractional charge and obey fractional statistics.
Impurity-induced quantum phase transition in finite Heisenberg spin chains: Criteria for existence and stability
Gang Chen,Yunxuan Li,Zheyong Fan,Huabi Zeng
Physics , 2014,
Abstract: A quantum phase transition may occur in a system at zero temperature when a controlling parameter is tuned towards a critical point. An important question is whether such a critical point exists in a particular system and how stable it is. Here, we identify the critical point of a quantum phase transition as a singular point in the affine algebraic variety of the characteristic equation for the Hamiltonian describing the system, with an unstable critical point being associated with an isolated singular point which has a finite Tjurina number. The theory is illustrated by studying a model system of zero-dimensional (finite) Heisenberg spin chain with an impurity, which exhibits a nontrivial first-order quantum phase transition. Both analytical and numerical calculations show that the quantum phase transition always exists when the impurity has a $Z_2$ symmetry but only remains in systems with an even number of spin sites when the $Z_2$ symmetry is broken.
Constructing quantum circuits for maximally entangled multi-qubit states using the genetic algorithm
Zheyong Fan,Hugo de Garis,Ben Goertzel,Zhongzhou Ren,Huabi Zeng
Physics , 2010,
Abstract: Numerical optimization methods such as hillclimbing and simulated annealing have been applied to search for highly entangled multi-qubit states. Here the genetic algorithm is applied to this optimization problem -- to search not only for highly entangled states, but also for the corresponding quantum circuits creating these states. Simple quantum circuits for maximally (highly) entangled states are discovered for 3, 4, 5, and 6-qubit systems; and extension of the method to systems with more qubits is discussed. Among other results we have found explicit quantum circuits for maximally entangled 5 and 6-qubit circuits, with only 8 and 13 quantum gates respectively. One significant advantage of our method over previous ones is that it allows very simple construction of quantum circuits based on the quantum states found.
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

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.
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