Magnetism and Stability of Diluted Magnetic Semiconductor (Ga_(1-x)Fe_x)As

Magnetism and the stability of (Ga 1-xFe x)As are investigated using the first principles LMTO-ASA band calculation by assuming supercell structures.Four concentrations of the 3d impurities are studied (x=1,1/2,1/4,and 1/8).The results show the effect of varying Fe concentration on the magnetic and stable properties.

确定块根类作物质量的电子仪器

在块根类作物果实内部，有吸收、干枯和老化的自然过程，如果能确定这些过程的进行情况，那么就有利于处理不同质量的果实——马上食用还是储存。俄罗斯圣彼得堡一所大学的科学家研制了一种叫做“电导计”的电子仪器，能够使人“看到”果实内部的情况。

确定块根类作物质量的电子仪器

在块根类作物果实内部，有吸收、干枯和老化的自然过程。如果能确定这些过程的进行情况，那么就有利于处理不同质量的果实——马上食用还是储存。俄罗斯圣彼得堡一所大学的科学家研制了一种叫做“电导计”的电子仪器。能够使人“看到”果实内部的情况。

Measurements of Conductivity for Low Concentration Strong-electrolytes in Organic Solvents (Ⅰ) LiBr, LiCl, and LiNO_3 in Alcohols

The conductivities of LiBr, LiCl, and LiNO 3 in methanol, ethanol, 1-propanol, and 2-propanol (with electrolyte concentrations <0.08 mol·L-1 ) were determined at 298.15 K, 313.15 K, and 323.15 K at atmosphere pressure separately by using a conductivity meter. The conductivity data were correlated with Foss-Chen-Justice (FCJ) equation and the limiting molar conductivities were obtained. The mean ionic activity coefficients of the salts in the organic solvents were calculated according to the Debye-Hückel limiting law and Onsager-Falkenhangen equations. The calculated results were compared with those activity coefficients in literature.

An integrated GPS /DR navigation system for AUV

GPS/Dead-reckoning navigation system for autonomous underwater vehicle (AUV) is introduced, which includes navigation overall architecture, hardware and software structure. Dead-reckoning theory is presented in details. And the strong tracking Kalman filter and Singer model are applied to handle the imprecise navigation mode, which can improve the navigation system’s precision and reliability. Finally, the sea experiments which include autonomous search mission in an unknown area and long distance motion are conducted to demonstrate the reliability and feasibility of the navigation system.

Solution to reinforcement learning problems with artificial potential field

A novel method was designed to solve reinforcement learning problems with artificial potential field.Firstly a reinforcement learning problem was transferred to a path planning problem by using artificial potential field(APF),which was a very appropriate method to model a reinforcement learning problem.Secondly,a new APF algorithm was proposed to overcome the local minimum problem in the potential field methods with a virtual water-flow concept.The performance of this new method was tested by a gridworld problem named as key and door maze.The experimental results show that within 45 trials,good and deterministic policies are found in almost all simulations.In comparison with WIERING's HQ-learning system which needs 20 000 trials for stable solution,the proposed new method can obtain optimal and stable policy far more quickly than HQ-learning.Therefore,the new method is simple and effective to give an optimal solution to the reinforcement learning problem.

Methodology for production logging in oil-in-water flows under low flow rate and high water-cut conditions

This study aimed to obtain the production profiles of oil-in-water flow under low flow rate and high water-cut conditions in oil wells.A combination production profile logging composed of an arc-type conductance sensor(ATCS)and a cross-correlation flow meter(CFM)with a center body is proposed and experimentally evaluated.The ATCS is designed for water holdup measurement,whereas the CFM with a center body is proposed to obtain the mixture velocity.Then,a drift-flux model based on flow patterns is established to predict the individual-phase superficial velocity of oil-in-water flows.Results show that the ATCS possesses high resolution in water holdup measurement and that flow pattern information can be deduced from its signal through nonlinear time series analysis.The CFM can enhance the correlation of upstream and downstream signals and simplify the relationship between the cross-correlation velocity and mixture velocity.On the basis of the drift-flux model,individual-phase superficial velocities can be predicted with high accuracy for different flow patterns.

Microstructure and thermophysical properties of Mg-2Zn-xCu alloys

The microstructure and thermophysical properties of Mg-2 Zn-x Cu alloys(x=0.5, 1.0 and 1.5, at.%) were investigated through microstructural and thermophysical characterization, heat treatment, and first-principles calculations. It was found that the addition of Cu had influence on the microstructure and thermophysical properties of the alloy. As the Cu content increased, the content of the MgCuZn phase increased in the as-cast alloys along with the electrical and thermal conductivities. After solution treatment, the eutectic structure partially decomposed and Zn atoms dissolved into the matrix, leading to the decrease in both the electrical and thermal conductivities of the alloy. During the early stages of the aging treatment, solute atoms precipitated from the matrix, thus increasing the electrical conductivity of the alloy. After aging for 24 h, the thermal conductivity of Mg-2 Zn-1.5 Cu alloy reached the maximum of 147.1 W/(m·K). The thermostable MgCuZn phases were responsible for increasing the electrical and thermal conductivities. Smaller amounts of Zn atoms dissolved in the matrix resulted in smaller lattice distortion and higher conductivities. The first-principles calculations findings also proved that the MgCuZn phases had very high conductance.

In-situ design and construction of lithium-ion battery electrodes on metal substrates with enhanced performances：A brief review

For the ever-growing demand of advanced lithium-ion batteries, it is highly desirable to grow self-supported micro-/nanostructured arrays on metal substrates as electrodes directly. The in-situ growth of electrode materials on the conducting substrates greatly simplifies the electrode fabrication process without using any binders or conductive additives. Moreover, the well-ordered arrays closely connected to the current collectors can provide direct electron transport pathways and enhanced accommodation of strains arisen from lithium ion lithiation/delithiation. This article summarizes our recent work on design and construction of lithium-ion battery electrodes on metal substrates. An aqueous solution-based process and a microemulsion-mediated process have been respectively presented to control the kinetic and thermodynamic processes for the micro-/nanostructured array growth on metal substrates, with particular attention to CuO nanorod arrays and microcog arrays successfully prepared on Cu foil substrates. They can be directly used as binder-free electrodes to build advanced lithium-ion batteries with high energy, high safety and high stability.

Substitution Effects on MgB2 Superconductivity

With the help of supercell method, the first-principle calculations were performed for the study of doping crystal Mg1-xAlxB2 and Mg（B1-yCy）2. Analyzing the variations of the charge distribution and the partial densities of states, we found that the compounds with doping Al to MgB2 compound and/or replacing boron by carbon exhibit new covalent bond effects and unexpected electronic properties, related to superconductivity. The study of the density of states indicates that superconductivity decreases with the increase of Al fraction and carbon concentration. There exists a transition of superconductor to non-superconductor with the change of Al doping fraction. The substitution of boron by carbon results in the decrease of the transition temperature since the decrease of the electron concentration and the lattice constant. The theoretical predictions agree with experimental observations.

Development and Optimization of an Alternative Methodology for Detection of Milk Adulteration by Water

This paper presents a process which allows the determination of milk adulteration by water. Considering the limitations of the reference method （cryoscopy）, the proposed methodology matches electrical conductivity and cryoscopy index measurements. Based on statistical procedures, a linear descriptive model is achieved to quantify adulteration of milk with water. It is also shown that electrical conductivity measurements allow the detection of adulteration with water and sodium chloride.

Model GC1312S Multifunction Integrated Optical Circuit Devices

Model GC1312S multifunction integrated optical circuit device (MIOC) used in inertial grade interferometric fiber optics gyroscopes (IFOGs) is fabricated by annealing and proton exchange process (APE). The unique feature of the device is the incorporation of the beat detection circuit besides all the features the conventional single Y branch multifunction integrated optical circuit devices have. The device structure, operation principle and typical characteristics, etc., are briefly presented in this paper.

Nonlinear Optical Response of Conjugated Polymer to Elec tric Field

The organic π-conjugate d polymers are of major interest materials for the use in electro-optical and no nlinear optical devices. In this work, for a selected polyacetylene chain, the optical absorption spectra in UV/Vis regime as well as the linear polarizabiliti y and nonlinear hyperpolarizability are calculated by using quantum chemical ab initio and semiempirical methods. The relationship of its optical property to el ectric field is obtained. Some physical mechanism of electric field effect on mo lecular optical property is discussed by means of electron distribution and intr amolecular charge transfer.

High Power Density Three-Level Three-Phase AC-DC 48 V Power Supply

International standards impose several constraints concerning the electric power quality and require that the harmonic content of the line current of grid connected equipment is below assigned limits; for this reason, operating of AC-DC converters with high power factor and low line current distortion has become essential. In this paper, the prototypal realization of a three-phase AC-DC 48 V power electronic converter for telecom system supplying is described and experimental testing results are discussed. The main constraints in the power supply design are the required power density of about 900 W per dm3 as well as the absence of the neutral wire in the supply grid. The carried out investigation is focused on three-level power converter configurations which are considered in order to reduce voltage rating of power switches. As a result of the reduced voltage, low on-resistance metal-oxide-semiconductor field effect transistors can be used in the power stage, solution which allows to achieve improved efficiency as well as increased switching frequency with respect to the insulated gate bipolar transistors based two-level topologies.

Dependence of Conductance of Corrugated Graphene Quantum Dot on Geometrical Features

Dependence of conductance of corrugated graphene quantum dot(CGQD)on geometrical features includinglength,width,connection and edge is investigated by the first principles calculations.The results demonstrate that theconductance of CGQD with different geometrical features is different from each other.The positions and amplitudesof discrete levels in densities of states and transmission coefficients are sensitive to geometrical features.The I-Vcharacteristics of graphene are modified by size and edge,it is surprise the current does not change monotonously butoscillatory with length.And they are slight change for different connections.

Low-Power MCML Circuit with Sleep-Transistor

This paper proposes a low-power MOS current mode logic （MCML） circuit with sleep-transistor to reduce the leakage current. The sleep-transistor is used to high-threshold voltage transistor to minimize the leakage current. The 16× 16 bit parallel multiplier is designed with the proposed technology. Comparing with the previous MCML circuit, the circuit achieves the reduction of the power consumption in sleep mode by 1/258. This circuit is designed with Samsung 0.35 um complementary metal oxide semiconductor （CMOS） process. The validity and effectiveness are verified through the HSPICE simulation.

Calculation Model of Effective Thermal Conductivity of a Spiral-wound Lithium Ion Battery

This paper proposed an analytical model which can calculate the effective thermal conductivity (ETC) of a spiral-wound Lithium-ion battery (Li-ion battery). It bases on a two-dimensional energy balance with both radial and spiral heat transfer, as well as internal thermal contact resistance (TCR) considered simultaneously and studies the influence of winding layers and winding tension on the ETC. Results show that the analytical data are in good agreement with the numerical results. With the winding layers decreased and the winding tension enhanced, the ETC of Li-ion battery increases gradually. The radial temperature in Li-ion battery is also investigated which demonstrates a relatively higher temperature when considering the internal TCR.

Selective DNA detection at Zeptomole level based on coulometric measurement of gold nanoparticle-mediated electron transfer across a self-assembled monolayer

A selective DNA sensing with zeptomole detection level is developed based on coulometric measurement of gold nanoparticle （AuNPs）-mediated electron transfer （ET） across a self-assembled monolayer on the gold electrode. After immobilization of a thiolated hairpin-structured DNA probe, an alkanethiol monolayer was self-assembled on the resultant electrode to block [Fe（CN）6]3-/4 in a solution from accessing the electrode. In the presence of DNA target, hybridization between the DNA probe and the DNA target breaks the stem duplex of DNA probe. Consequently, stem moiety at the 3＇-end of the DNA probes was removed from the electrode surface and made available for hybridization with the reporter DNA-AuNPs conjugates （reporter DNA-AuNPs）. The thiolated reporter DNA matches the stem moiety at the 3＇-end of the DNA probe. AuNPs were then en- larged by immersing the electrode in a growth solution containing HAuCI4 and H202 after the reporter DNA-AuNPs bound onto the electrode surface. The enlarged AuNPs on the electrode restored the ET between the electrode and the [Fe（CN）6]3 -/4-, as a result, amplified signals were achieved for DNA target detection using the coulometric measurement of Fe（CN）63- elec- tro-reduction by prolonging the electrolysis time. The quantities of ET on the DNA sensor increased with the increase in DNA target concentration through a linear range of 3.0 fM to 1.0 pM when electrolysis time was set to 300 s, and the detection limit was 1.0 fM. Correspondingly, thousands of DNA （zeptomole） copies were detected in 10-μL samples. Furthermore, the DNA sensor showed excellent differentiation ability for single-base mismatch.

Calculation model of AC loss for CICC(cable-in-conduit conductor) based on strain

The CICC (cable-in-conduit conductor) in ITER (International Thermal-nuclear Experimental Reactor) will run in high-current, fast transient magnet field and complex environment. In response to the impact of magnet fields above 10 T, the Nb3Sn conductor has been introduced. However, the AC (alternating current) loss mechanism of Nb3Sn conductor on strain has not been explored. So, it is necessary to study the AC loss calculation method with transient electromagnetic field and wide range of strain, the coupling current in complex field and current signal of field is simplified to the spectrum effects of coil excitation, and calculation technology of AC loss, which contains the frequency, magnet field, coil characteristics and other parameters, is constructed to meet the discrete Fourier transform (DFT). By comparative analysis of simulation, it is found that the AC loss calculation of the conductor with spectrum algorithm is closer to the actual project value than the traditional algorithm. For the rapid excitation, in particular plasma discharge and burst, spectrum algorithm and the traditional algorithm are consistent. For the relative error calculation of hysteresis loss and coupling loss, it is found that the coupling loss is cumulative linearly, where the hysteresis loss is not so. As a function of the amplitude, frequency and phase angle, the relative error is less than 40%. The results showed that the method of Fourier restructuring is satisfactory.

Anion exchange membranes with eight flexible side-chain cations for improved conductivity and alkaline stability

Increasing the local charge density of flexible side-chain cations in the hydrophilic segments of anion exchange membranes(AEMs)is helpful for improving their properties.However,due to limitations of structural design strategies and available synthetic methods,very few AEMs with more than four flexible side-chain cationic groups in hydrophilic segments have been reported.In order to further improve the hydroxide conductivity,alkaline stability and dimensional stability,herein we report a series of AEMs containing eight flexible side-chain cations in hydrophilic segments,based on poly(aryl ether sulfone)s(PAES).The synthesis,ion exchange capacity(IEC),water absorption,dimensional swelling,alkaline stability and hydroxide conductivity of the obtained membranes(PAES-8TMA-x)were examined and the relationships between structures and properties of different types of AEMs were also systematically compared.The resulting AEMs with IEC values of1.76–2.76 mmol g^-1 displayed comprehensively desirable properties,with hydroxide conductivities of 62.7–92.8 m S cm^-1 and dimensional swelling in the range of 8.3%to15.8%at 60℃.The IEC and hydroxide conductivity for a representative sample,PAES-8TMA-0.35,maintained 82.2%and 79.6%of the initial values after being immersed in2 mol L^-1 Na OH at 90℃ for 480 h,respectively.This study expands the design and preparation of AEMs containing high local densities of flexible side chain cations,and provides a new strategy for new AEM materials.