FeNi-Si-C体系金刚石的成核特性

本文利用掺硅FeN i粉末触媒,在国产六面顶压机上进行了金刚石单晶的合成实验,研究了高温高压条件下,FeN i-S i-C体系合成金刚石单晶的成核特性。结果表明,由于掺S i量的不同,合成金刚石的最低生长条件(压力和温度)并没有太大的改变;但随着触媒中掺S i量的增加,其成核量也随之增加;通过光学成像显微镜观测发现,合成出的金刚石晶体同FeN i-C体系合成的晶体的颜色和形貌具有较大的区别,出现了“两极分化”现象,主要表现为部分晶体质量好,而部分晶体则质量很差(晶体呈浅黑色,晶形不完整等),且随触媒中掺S i量的增加,质量差的晶体比率增高。对不同合成条件的棒料进行X-ray检测发现,在金刚石合成条件下有FeS i和Fe3S i的生成,台阶压力时间的长短直接影响FeS i、Fe3S i的粒度。我们推测,难熔化合物FeS i和Fe3S i参与成核,导致金刚石成核量增加,而这种金刚石的“异形核”存在,会导致晶形不够完整和包裹体的产生。

Comparison of Nucleic Acid Content among Non-diapause Pupae, Diapause Pupae and Eclosion-adult from Diapause Pupae of Papilio memnon

[Objective] The aim of this study was to provide basis for deeply understanding the diapause mechanism of Papilio memnon L. [Method] RNA and DNA content of non-diapause pupae, diapause pupae and eclosion-adult from diapause pupae at different development stages were detected by the colorimetry. [Result] RNA content of non-diapause pupae was 4.614 0-7.946 3 μg/mg, while diapause pupae was 4.326 0-5.885 3 μg/mg and eclosion-adult from diapause pupae was 20.779 3 μg/mg at initial stage. DNA content of non-diapause pupae was 0.448 7-0.535 0 μg/mg, while diapause pupae was 0.452 0-0.828 3 μg/mg and eclosion-adult from diapause pupae was 1.727 0 μg/mg at initial stage. [Conclusion] The nucleic acid content and change is related to the development stage.

Experimental investigation of crystallization process of nanofluid by DSC

A water-TiO2nanofluid with a weight fraction of 5% and an average particle size of 75 nm is used to investigate the effect of TiO2 nanoparticles on the crystallization and melting behaviors of deionized water by using differential scanning calorimetry（DSC）at four different cooling rates,3,5,7,9 ℃/min.The DSC experimental results show that the water-TiO2 nanofluid has a lower supercooling degree and a faster crystallization rate than the deionized water.With the increase in the cooling rate,the influence of the TiO2 nanoparticles on the supercooling degree of the deionized water becomes greater,but on the crystallization rate it turns lower.During the melting process,compared with the deionized water,the water-TiO2 nanofluid has a lower melting temperature,a less latent heat and a higher melting rate.

Study on Improvement of Walnut Bud Grafting Technology in the North

[Objective] This study was conducted to change the situation of high cost in walnut grafting by reducing seedling cost through technical means.[Method] Effects of different rootstock processing methods and rootstock pruning time on walnut growth and cost were studied by the square bud grafting method.[Result] The survival rate and cost under stumping were higher than those under no stumping,and the proportion of grafting-capable rootstocks under stumping was lower than that under no stumping by 9%.The cost differences between different rootstock time were remarkable.The cost for the stock pruning 15 d after grafting was 5 times as much as 1 d after grafting.[Conclusion] Direct grafting could achieve the effect of easy and convenient management,and the overall cost was lower though the survival rate was reduced to a limited extent.Sooner rootstock pruning resulted in a better effect.Pruning the rootstocks within 5 d after grafting not only could improve the quality of seedlings,but also could reduce the cost for seedling management.

Identification of nucleation parameter for cellular automaton model of dynamic recrystallization

The accuracy of nucleation parameter is a critical factor in the simulation of microstructural evolution during dynamic recrystallization(DRX).Based on the flow stress curve under hot deformation conditions,a new approach is proposed to identify the nucleation parameter during DRX.In this approach,a cellular automaton(CA) model is applied to quantitatively simulate the microstructural evolution and flow stress during hot deformation;and adaptive response surface method(ARSM) is applied as optimization model to provide input parameters to CA model and evaluate the outputs of the latter.By taking an oxygen-free high-conductivity(OFHC) copper as an example,the good agreement between the simulation results and the experimental observations demonstrates the availability of the proposed method.

Depression discrimination using fMRI and DTI data by wavelet based fusion scheme

Both functional magnetic resonance imaging （fMRI） and diffusion tensor imaging （DTI） can provide different information of the human brain, so using the wavelet transform method can achieve a fusion of these two types of image data and can effectively improve the depression recognition accuracy. Multi-resolution wavelet decomposition is used to transform each type of images to the frequency domain in order to obtain the frequency components of the images. To each subject, decomposition components of two images are then added up separately according to their frequencies. The inverse discrete wavelet transform is used to reconstruct the fused images. After that, principal component analysis （PCA） is applied to reduce the dimension and obtain the features of the fusion data before classification. Based on the features of the fused images, an accuracy rate of 80. 95 % for depression recognition is achieved using a leave-one-out cross-validation test. It can be concluded that this wavelet fusion scheme has the ability to improve the current diagnosis of depression.

Modeling and monitoring of nonlinear multi-mode processes based on similarity measure-KPCA

A new modeling and monitoring approach for multi-mode processes is proposed.The method of similarity measure(SM) and kernel principal component analysis(KPCA) are integrated to construct SM-KPCA monitoring scheme,where SM method serves as the separation of common subspace and specific subspace.Compared with the traditional methods,the main contributions of this work are:1) SM consisted of two measures of distance and angle to accommodate process characters.The different monitoring effect involves putting on the different weight,which would simplify the monitoring model structure and enhance its reliability and robustness.2) The proposed method can be used to find faults by the common space and judge which mode the fault belongs to by the specific subspace.Results of algorithm analysis and fault detection experiments indicate the validity and practicability of the presented method.

Quantum Nucleation of Antiferromagnetic Bubbles with Tetragonal and Hexagonal Symmetries

We study the quantum nucleation in a nanometer-scale antiferromagnet placed in a magnetic field at an arbitrary angle. We consider the magnetocrystalline anisotropy with tetragonal symmetry and that with hexagonal symmetry, respectively. Different structures of the tunneling barriers can be generated by the magnitude and the orientation of the magnetic field. We use the instanton method in the spin-coherent-state path-integral representation to calculate the dependence of the rate of quantum nucleation and the crossover temperature on the orientation and strength of the field for bulk solids and two-dimensional films of antiferromagnets, respectively. We find that the rate of quantum nucleation and the crossover temperature from thermal-to-quantum transitions depend on the orientation and strength of the external magnetic field distinctly, which can be tested by use of existing experimental techniques.

Quantitative Estimation of Directional Permeability Barrier as Reservoir Heterogeneity A New Approach Using Synthetic Core

One of the major challenges in reservoir characterization is to estimate the effective porosity and the permeability of the reservoir due to reservoir heterogeneity. Often, the vertical and the horizontal permeabilities are not considered separately in 3D geo-cellular models and in the reservoir simulations. Conventional reservoir modeling extrapolates all of the small-scale data to full-field scale data without considering the impact of the small-scale geological details, and therefore carries forward inherent errors into the reservoir predictions as a consequence of ignoring the reservoir heterogeneity. Most reservoirs are geologically complex and heterogeneous and that greatly influences reservoir performance. A case study is taken from a CHOPS （cold heavy oil production with sands） field. An innovative method of reservoir heterogeneity estimation has been introduced to illustrate the complex reservoir heterogeneity honouring all of the small-scale geological details in the 3D geological model. This detailed near-wellbore modeling through a synthetic core can provide the realistic quantitative volumetric assumption of the production prediction and improve the EOR （enhanced oil recovery） processes.

Ferronickel preparation using Ni-Fe co-deposition process

Nucleation mechanism and technological process for Ni-Fe co-deposition with a relatively high Fe^(2+)concentration surrounded were described,and the effects of Fe^(2+) concentration,solution pH,temperature,and sodium dodecyl sulfonate concentration were investigated.Electrochemical experiments demonstrate that iron's electrodeposition plays a leading role in the Ni-Fe co-deposition process,and the co-deposition nucleation mechanism accords with a progressive nucleation.Temperature increase does favor in increasing nickel content in the ferronickel(Ni-Fe co-deposition products),while Fe^(2+) concentration increase does not.When solution pH is higher than 3.5,nickel content in the ferronickel decreases with pH because of the hydrolysis of Fe^(2+).With the current density of 180 A/m^2,Na_2SO_4 concentration of 100 g/L and Ni^(2+) concentration of 60 g/L,a smooth ferronickel deposit containing 96.21% Ni can be obtained under the conditions of temperature of 60 °C,Fe^(2+) concentration of 0.3 g/L,solution pH of 3 and sodium dodecyl sulfonate concentration of 40 mg/L.

On Q Values and Other Energy Parameters for Superheavy Element Synthesis

Q value and optimal exciting energy of hypothetical superheavy nuclei in cold fusion reaction are calculated with relativistic mean field model and semiemperical shell model mass equation (SSME) and the validity of the two models is tested. To give useful references for the experiments in the superheavy nuclei synthesized in cold fusion reactions,the Q value, fusion barrier and optimal exciting energy for the possible target plus projectile combinations suggested by Gupta et al. are calculated and the most possible target plus projectile combinations are pointed out according to our calculations.

Comparison between PCA and KPCA methods in comprehensive evaluation of robotic kinematic dexterity

Due to the correlation and diversity of robotic kinematic dexterity indexes, the principal component analysis （PCA） and kernel principal component analysis （KPCA） based on linear dimension reduction and nonlinear dimension reduction principle could be respectively introduced into comprehensive kinematic dexterity performance evaluation of space 3R robot of different tasks. By comparing different dimension reduction effects, the KPCA method could deal more effectively with the nonlinear relationship among different single kinematic dexterity indexes, and its calculation result is more reasonable for containing more comprehensive information. KPCA＇ s calculation provides scientific basis for optimum order of robotic tasks, and furthermore a new optimization method for robotic task selection is proposed based on various performance indexes.

The Applic ation of Internal Quality Audit in ADCOP Project

Internal quality audits are a key activity in the quality management ofoil projects.Quality management aims at meeting project quality requirements,coordinatingproject progress,assisting in controlling project costs,and realizing continuousimprovement in project quality management.

First result from the Jinping Underground Nuclear Astrophysics experiment JUNA:precise measurement of the 92 keV ^(25)Mg(p,γ)^(26)Al resonance

The ^(25)Mg(p,γ)^(26)Al reaction plays an important role in the study of cosmic 1.809 MeV γ-ray as a signature of ongoing nucleosynthesis in the Galaxy.At astrophysical temperature around 0.1 GK,the ^(25)Mg(p,γ)^(26)Al reaction rates are dominated by the 92 keV resonance capture process.We report a precise measurement of the 92 keV ^(25)Mg(p,γ)^(26)Al resonance in the day-one experiment at Jinping Underground Nuclear Astrophysics experiment(JUNA)facility in the China Jinping Underground Laboratory(CJPL).The resonance strength and ground state feeding factor are determined to be 3.8±0.3×10^(-10) eV and 0:660:04,respectively.The results are in agreement with those reported in the previous direct underground measurement within uncertainty,but with significantly reduced uncertainties.Consequently,we recommend new ^(25)Mg(p,γ)^(26)Al reaction rates which are by a factor of 2.4 larger than those adopted in REACLIB database at the temperature around 0.1 GK.The new results indicate higher production rates of ^(26g)Al and the cosmic 1.809 MeV γ-ray.The implication of the new rates for the understanding of other astrophysical situations is also discussed.

Comparison of Mg^(2+)- and Ca^(2+)-enhancing anaerobic granulation in an expanded granular sludge-bed reactor

The mechanisms responsible for the fast granulation of anaerobic sludge caused by Mg2+ and Ca2+ addition was examined in four lab-scale expanded granular sludge bed(EGSB) reactors. Results indicated that both Mg2+ and Ca2+ accelerated the sludge-granulation process and increased the amount of polysaccharides and proteins in the sludge. Energy dispersive x-ray spectrometry(EDX) analysis revealed that, in a mature granule, both Mg2+ and Ca2+ composed as phosphate and calcium was distributed primarily in the periphery of the granule, while magnesium distributed mainly in the interior. The addition of Mg2+ was more favorable for the nuclei formation, whereas the addition of Ca2+ was more favorable for subgranule growth and maintaining the granules' rigid structure. Results showed that the addition of Mg2+ in the nuclei formation stage and Ca2+ in the granule-growth stage accelerated granulation more than adding only one of them in the granulation process.

Quasi-periodic variations of low energy cosmic rays

Cosmic rays(CR)play an important role in space weather-related studies.Their temporal variability,both of a quasi-periodic character as well as an irregular one,has been studied from ground-based direct measurements,as well as from cosmogenic nuclides,over a long time.We attempt to describe the current knowledge of selected quasi-periodicities in CR flux in the energy range above the atmospheric threshold,from direct measurements.The power spectrum density(PSD)of the CR time series as measured by neutron monitors(NMs)and by muon detectors has a rather complicated character.Along with the shape(slope)of the PSD,knowledge of the contribution of quasi-periodic variations(q-per)to the CR signal is of importance for the modulation,as well as for checking the links of CR to space weather,and/or to space climate effects.The rotation of the Earth and solar rotation cause two types of mechanisms behind the certain q-per observed in secondary CR on the Earth’s surface.Solar activity and solar magnetic field cyclicities contribute to the q-per signals in CR if studied over a longer time.The complexity of the spatial structure of the interplanetary magnetic field(IMF)and its evolution within the heliosphere,in addition to the changes in the geomagnetic field,cause variability in contributions of the q-per in CR.Wavelet spectra are useful tools for checking the fine structure of q-per and their temporal behaviour.Over a long time NMs and muon telescopes provide information about q-per in CR.