Temporal and spatial variabilities of sea surface heights in the northeastern South China Sea

Analyses of sea surface height anomalies (SSHA) from Jan. 1993 to Dec. 2001 measured by TOPEX/Poseidon (T/P) satellite altimetry indicate that there are two energy highs of SSHA fluctuations on both sides of the Luzon Strait. The highs centered at (19.5°N, 119.5°E) and (22.0°N, 124.0°E) respectively, are separated by a low energy band in the Strait. Empirical Orthogonal Function (EOF) analysis on the "Far Field" suggests that fluctuations of these two areas are mutually independent. EOF analysis on the "Near Field" shows that SSHA oscillation in the northeastern South China Sea (SCS) is dominated by seasonal variations accompanied with significant intra-seasonal and inter-annual fluctuations. Among which, EOFI and EOF2 reflect 66.7% of the total variance. They are both seasonal but showing three months difference in phase. The basic pattern of EOFI appears to be the seasonal SSHA oscillation centered at (18.0°N, 119.0°E) northwest off Luzon Island, which shows maximums (minimums) in August/Septemb     

Observable Algebra in Field Algebra of G-spin Models

Field algebra of G-spin models can provide the simplest examples of lattice field theory exhibiting quantum symmetry. Let D(G) be the double algebra of a finite group G and D(H), a sub-algebra of D(G) determined by subgroup H of G. This paper gives concrete generators and the structure of the observabl ealgebra AH, which is a D(H)-invariant sub-algebra in the field algebra of G-spin models F, and shows that AH is a C^*-algebra. The correspondence between H and AH is strictly monotonic. Finally, a duality between D(H) and A. is given via an irreducible vacuum C^* -representation of F.     

CIC filter theory in DDC and implementation by using FPGA

Cascade Integrator Comb(CIC)filter is the main part of the next generation High Frequency (HF) radar. This paper describes the key points of CIC theory in the Digital Down Conversion (DDC) module of a radar receiver, and takes advantage of the high flexibility and high density feature of Field Programmable Gate Array (FPGA) for putting forth to design the CIC filter by using FPGA. This paper provides particular insight into design by FPGA, which has advantages in high speed operation and simply structure. Some important and practical applications are given in this paper. The simulation result proves the validity and veracity. Because we can adjust the parameters freely according to our need, the CIC filter can be adapted to the next generation HF radar.     

搅拌铸造法制备和表征GNPs和CNTs增强Al 7075基复合材料

This study investigated the effects of adding graphene nanoplates (GNPs) and carbon nanotubes (CNTs) into the Al7075 matrix via the stir casting method on the microstructure and mechanical properties of the fabricated composites. By increasing the volume fraction of reinforcements, the fraction of porosity increased. The X-ray diffraction results showed that the addition of reinforcements into the Al7075 changed the dominant crystal orientation from (002) to (111). Field emission scanning electron microscopy images also showed the distribution of clustered reinforcements in the matrix. Between the two reinforcements, the addition of CNTs generated a lower fraction of porosities. Through the addition of 0.52vol% GNPs into the matrix, the hardness, ultimate tensile strength and uniform elongation increased by 44%, 32%, and 180%, respectively. Meanwhile, the presence of 0.71vol% CNTs in the matrix increased the hardness, tensile strength and uniform elongation by 108%, 129%, and 260%, respectively.     

JOURNAL OF DALIAN INSTITUTE OF TECHNOLOGYTotal Contents of Volume 19

Number 1Theory of Microphase Separation in Block Copolymers………………………………………………………………………………Li Luhui Zhao Guoliang (13)The Development of a Field Equipment for Rating the Gas Contentof the Molten Cu-Alloys and the Evalutaion of Measuring Errors………………………………………………………………………………Guo Keren　Cao Qin Zhang Guoliang (25)The Generalized Variational Principles in Theory of Creep…………………………………………………………………………………     

Molecular design of new chromophores for high performance poled polymers

：Based on the principles of molecular engineering, a series of new chromophores with high second-or der nonlinear optical(NLO)activities have been designed for achieving a trade-off of the nonlinearity-transparency-ther mal stability. The NLO properties of these chromophores have been investigated theoretically by employing the AMI/Fi nite Field approach. It is found that the calculated μβ0 values of some designed chromophores can reach the magnitude of 10-45 esu, and the highest decomposition temperature Td can be as high as 377℃, the highest glass transition tem perature Ts of their donor-embedded addition-type polyimides can be as high as 324℃.     

Comparative study of a substorm event by satellite observation and model simulation

A substorm event has been simulated for the first time by using SWMF (Space Weather Modeling Framework) developed by the University of Michigan. The model results have been validated using Geotail and Cluster satellite observations. The substorm onset occurs at 22:08 UT on September 28, 2004, as identified from FUV WIC observations on the NASA IMAGE spacecraft. SWMF can couple effectively the magnetosphere, inner magnetosphere and ionosphere processes and is driven by the solar wind and IMF (Interplanetary Magnetic Field) parameters, which are measured by ACE satellite and time delayed to the upstream boundary of the model. It shows that (1) SWMF can predict well the large-scale variations of the magnetospheric magnetic field and ionospheric currents during the substorm event; and (2) the accuracy of the time delay of the solar wind from ACE to the outer boundary of the model has great effects on the model results. Finally, the substorm trigger mechanism has been discussed and the way of improvement of the model has been pointed out.     

JOURNAL OF XI′AN JIAOTONG UNIVERSITY 2007 Annual Classification Index Title(Issue/Page)

Management ScienceEmission Permits Option Value Evaluation Model(1/106)Oneness of Modern Credit Risk Models(1/110)Detecting Algorithm Based on Prior Knowledge and Modu-larity for Networked Community Structure(6/750)Nature Science and MathematicsZak Transformand Sampling Theoremin the Shift InvariantSubspace(10/1248)Inverse Power Method for Source TermInversionin NeutronTransport Equation(4/493)Numerical Si mulation of Responses of Spiral Wave to Exter-nal Vector Field for Com…     

Differential Coherent Algorithm Based on Fast Navigation-Bit Correction for Airborne GNSS-R Software Receivers

Signals from the Global Navigation Satellite System (GNSS) scatter over the sea surface resulting in relatively low Signal-to-Noise Ratios (SNR). A differential coherent algorithm is given here to improve the SNR and reduce the performance degradation due to the Squaring-Loss and the navigation-bit effect. The algorithm uses fast navigation-bit correction for Delay-Doppler Maps (DDM) in airborne Global Navigation Satellite Signal Reflectometry (GNSS-R) software receivers. The system model is introduced with an analysis of the statistical properties with simulations to support the theoretical analysis. Field experiments with real airborne receivers then demonstrate the effectiveness of this algorithm. Comparisons with test results show that this algorithm offers a significant SNR gain over conventional algorithms.     

An FPGA Implementation of GF （p） Elliptic Curve Cryptographic Coprocessor

A GF (p) elliptic curve cryptographic coprocessor is proposed and implemented on Field Programmable Gate Array (FPGA). The focus of the coprocessor is on the most critical, complicated and time-consuming point multiplications. The technique of coordinates conversion and fast multiplication algorithm of two large integers are utilized to avoid frequent inversions and to accelerate the field multiplications used in point multiplications. The characteristic of hardware parallelism is considered in the implementation of point multiplications. The coprocessor implemented on XILINX XC2V3000 computes a point multiplication for an arbitrarypoint on a curve defined over GF(2^192-2^64-1) with the frequency of 10 MHz in 4.40 ms in the average case and 5.74ms in the worst case. At the same circumstance, the coprocessor implemented on XILINX XC2V4000 takes 2.2 ms in the average case and 2.88 ms in the worst case.     

Addition of IrO2 to RuO2+TiO2 coated anodes and its effect on electrochemical performance of anodes in acid media

Ternary mixed metal oxide coatings with the nominal composition IrxRu(0.6-x)Ti0.4O2(x=0, 0.1, 0.2, 0.3) on the titanium substrate were prepared by thermal decomposition of a chloride precursor mixture. Surface morphology and microstructure of the coatings were investigated by Scanning electron microscopy(SEM), Field emission scanning electron microscopy(FE-SEM) and X-ray diffraction(XRD) analysis. Systematic study of electrochemical properties of these coatings was performed by cyclic voltammetry(CV) and polarization measurements. The corrosion behavior of the coatings was evaluated under accelerated conditions(j=2 A cm-2) in acidic electrolyte. The role of iridium oxide admixture in the change of electrocatalytic activity and stability of Ru0.6Ti0.4O2coating was discussed. Small addition of IrO2can improve the stability of the RuO2+TiO2mixed oxide, while the electrocatalytic activity for oxygen evolution reaction(OER) is decreased. The shift of redox potentials for Ru0.6Ti0.4O2electrode that is slightly activated with IrO2and improvement in the stability can be attributed to the synergetic effect of mixed oxide formation.     

Application of gap elememt to nonlinear mechanics analysis of drillstring

This paper presents a nonlinear finite element method to resolve the problem of the nonlinear contact between the drillstring and hole by using a Multi-directional Contract Gap Element(MCGE) contacting at approprizte positions in each beam element.The method was successfully applied to the Daqing Oil Field GP1 well.It was shown that the drillstring‘s contact resistance at any well depth could be obtained by calculations and that as the enor in the calculation of the hole top load is below 10%,the calculation result can provide theoretical basis for the design and operation of drillstrings.     

Non-spherical aluminum nanoparticles fabricated using picosecond laser ablation

We report the picosecond laser ablation of aluminum targets immersed in a polar organic liquid(chloroform, CHCl3) with ～2 ps laser pulses at an input energy of ～350 μJ. The synthesized aluminum nanoparticles exhibited a surface plasmon resonance peak at ～340 nm.Scanning electron microscopy images of Al nanoparticles demonstrated the spherical morphology with an average size of(27 ± 3.6) nm. The formation of smaller spherical Al nanoparticles and the diminished growth could be from the formation of electric double layers on the Al nanoparticles. In addition to spherical aluminum nanoparticles, triangular/pentagonal/hexagonal nanoparticles were also observed in the colloidal solution. Field emission scanning electron microscopy images of ablated Al targets demonstrated laser induced periodic surface structures(LIPSSs), which were the high spatial frequency LIPSSs(HSF-LIPSSs) since their grating period was ～280 nm. Additionally, coarse structures with a period of ～700 nm were observed.     

利用皮秒激光烧蚀制备非球形铝纳米颗粒

We report the picosecond laser ablation of aluminum targets immersed in a polar organic liquid (chloroform, CHCl₃) with ~2 ps laser pulses at an input energy of ~350 μJ. The synthesized aluminum nanoparticles exhibited a surface plasmon resonance peak at ~340 nm. Scanning electron microscopy images of Al nanoparticles demonstrated the spherical morphology with an average size of (27 ± 3.6) nm. The formation of smaller spherical Al nanoparticles and the diminished growth could be from the formation of electric double layers on the Al nanoparticles. In addition to spherical aluminum nanoparticles, triangular/pentagonal/hexagonal nanoparticles were also observed in the colloidal solution. Field emission scanning electron microscopy images of ablated Al targets demonstrated laser induced periodic surface structures (LIPSSs), which were the high spatial frequency LIPSSs (HSF-LIPSSs) since their grating period was ~280 nm. Additionally, coarse structures with a period of ~700 nm were observed.     

Intense laser induced field ionization of C<Subscript>2</Subscript>H<Subscript>2</Subscript>, C<Subscript>2</Subscript>H<Subscript>4</Subscript>, and C<Subscript>2</Subscript>H<Subscript>6</Subscript>

Using HOMO Field Ionization Model, the tunneling probabilities and the theoretical threshold intensities of the field ionizations of acetylene, ethylene, and ethane in intense laser field are calculated. C2H2, C2H4, and C2H6 were irradiated by 800 nm, 100 fs laser pulses with the intensity range of 10^13-10^14 W/cm^2. A TOF-mass spectrometer was coupled to the laser system and used to experimentally investigate the field ionization of these molecules. The experimental ionization threshold intensities are obtained. The calculating results of the three molecules agree well with the experimental results, indicating that HOMO Field Ionization Model is valid for the ionization of polyatomic molecules in intense laser field.     

Zircon SHRIMP U-Pb geochronology and petrogenesis of the plagiogranites from the Lagkor Lake ophiolite, Gerze, Tibet, China

Field relationship, along with petrographical, petrological, and geochemical characteristics, and zircon populations, indicates that the plagiogranites from the Lagkor Lake ophiolite in the Bangong-Nujiang suture zone (~ 20 km south of Gerze County, central Tibet, China), derived from anatexis of hydrated gabbros by ductile shearing during transport of the oceanic crust. Therefore, this kind of plagiogranite is coeval to or little later than the spreading of the oceanic crust. Zircon SHRIMP age of 166 ± 2.5 Ma for the plagiogranites indicates that an oceanic basin existed in the western part of the Bangong-Nujiang zone in the Middle Jurassic.     

Study on Applying Hybrid Machine Learning into Family Apparel Expenditure

Hybrid Machine Learning (HML) is a kind of advanced algorithm in the field of intelligent information process. It combines the induced learning based-on decision-making tree with the blocking neural network. And it provides a useful intelligent knowledge-based data mining technique. Its core algorithm is ID3 and Field Theory based ART (FTART). The paper introduces the principals of hybrid machine learning firstly, and then applies it into analyzing family apparel expenditures and their influencing factors systematically. Finally, compared with those from the traditional statistic methods, the results from HML is more friendly and easily to be understood. Besides, the forecasting by HML is more correct than by the traditional ways.     

High Precision Absolute Gravity Meter Based on Time-to-Digital Conversion in FPGA

This paper proposes a novel method to design a high precision portable gravity acceleration meter on the Field Programmable Gate Array(FPGA) platform. Two technologies are used in FPGA to improve the time measurement accuracy to 54 ps and the measurement accuracy of g to the level of 1 μGal(1 Gal=1 cm/s~2). The one is the proposed clock rising edge counting method for measuring the coarse time, in which the measured coarse time resolution can reach 5 ns by setting the clock frequency up to 200 MHz. The other is the realization of the time-to-digital conversion(TDC) circuits in FPGA which can further improve the time measurement accuracy to 54 ps. In the TDC circuit, we analyze the influence of the frequency stability of crystal oscillator and the distance of infrared tube on the measurement accuracy of g. The increase of frequency stability(10~(–9) to 10~(–11)) can greatly improve the measurement accuracy of g(5.814 3 to 2.079 9 μGal), but further increase of frequency stability(10~(–11) to 10~(–12)) has little effect on improving the accuracy of g. Through analysis and simulation, it is found that the setting of distance between laser pair also has a great influence on the accuracy of g. Only when the distance is set to the optimal, we can make the accuracy of g the highest. In this paper, the method of obtaining the best distance and the corresponding accuracy of g are given. In addition, the proposed system uses Nios II soft core processor to implement all the controlling, calculation and display functions, which improves system integration, reduces system cost and meets the needs of field geological survey and gravity prospecting.     

Dependence of magnetic field just inside the magnetopause on subsolar standoff distance: Global MHD results

The subsolar magnetopause is the boundary between the solar wind and the Earth’s magnetosphere,where reduced solar wind dynamic pressure is equal to the magnetic pressure of the Earth’s outer magnetosphere.We use a global magnetohydrodynamic (MHD)model to estimate the ratio f of the compressed magnetic field just inside the subsolar magnetopause to the purely dipolar magnetic field.We also compare our numerical results to a similar work by Shue,which used Time History of Events and Macroscale Interactions during Substorms(THEMIS)data.Our results show that the ratio f is linearly proportional to the subsolar magnetopause standoff distance(r0)for both the northward and southward interplanetary magnetic field,properties consistent with Shue but with a smaller proportionality constant.However,previous theoretical studies show that f is nearly independent of the subsolar standoff distance.The global model results also show that f is smaller for the southward Interplanetary Magnetic Field(IMF)under the same r0,and that the proportionality constant for the southward IMF is larger than that for the northward IMF.Both conclusions agree with statistical results from observations by Shue.     

Dynamics of total culturable bacteria and its relationship with methylmercury in the soils of the water level fluctuation zone of the Three Gorges Reservoir

Field investigations were conducted to study the temporal and spatial distribution characteristics of total culturable bacteria(TCB)and its relationship with methylmercury(MeHg)in the soils of the water level fluctuation zone of the Three Gorges Reservoir.Different altitudes(170–180,170–175,165–170 and 160–165 m)in Zhenxi(Site 1),Shibaozhai(Site 2)and Tujing(Site 3),Chongqing,China were chosen as sampling sites.Results indicated that TCB did not have significant difference in the top(0–10 cm)and sub(10–20 cm)soil of the non-inundated area(175–180 m),but showing a significant difference in the water level fluctuation zone(\175 m,suggesting that water level fluctuation had an important effect on TCB.Moreover,TCB in soils of various altitudes of Site 1 and 2had significant difference,while for Site 3,this difference was not significant.And the difference of TCB in Site 2was much greater than that in Site 1.These results suggested that there were significant differences for TCB in soils of mainstream and tributaries.In addition,TCB in soils of 10–20 cm had significant or highly significant positive correlations with MeHg level(r C 0.762,P B 0.048),thus we assumed that there may be some aerobic microorganisms playing dominant roles in mercury methylation.