Dynamic Behavior of Interest Rates in China

This paper intuitively examines the dynamic behavior of two highly relevant interest rates in China. The first one is the government rate, which is decided and published by the central bank and can be simulated by pure jump process. Estimation of the jump intension is given out. And by different robustness test, it keeps stable. The jump size has met the condition to make interest rate within reasonable bounds and shown some meaning of economic cycle behavior. The second one is the market rate, which is estimated by spline approximation based on the transaction data of government bonds. Several models, including Vasicek model, Vasicek-GARCH （1,1） model, CIR model, and CIR-GARCH（1,1）, are empirically tested and the best performance is done by the Vasicek-GARCH（1,1） model. Furthermore, the estimate bias problem due to the near unit root process is tested and evidenced by both traditional methods and GPH test. Impact of government rate on market rate is finally checked and analyzed.

Effect of strain rate and water-to-cement ratio on compressive mechanical behavior of cement mortar

Effects of strain rate and water-to-cement ratio on the dynamic compressive mechanical behavior of cement mortar are investigated by split Hopkinson pressure bar(SHPB) tests. 124 specimens are subjected to dynamic uniaxial compressive loadings.Strain rate sensitivity of the materials is measured in terms of failure modes, stress-strain curves, compressive strength, dynamic increase factor(DIF) and critical strain at peak stress. A significant change in the stress-strain response of the materials with each order of magnitude increase in strain rate is clearly seen from test results. The slope of the stress-strain curve after peak value for low water-to-cement ratio is steeper than that of high water-to-cement ratio mortar. The compressive strength increases with increasing strain rate. With increase in strain rate, the dynamic increase factor(DIF) increases. However, this increase in DIF with increase in strain rate does not appear to be a function of the water-to-cement ratio. The critical compressive strain increases with the strain rate.

In-plane Tensile Behaviors of Bi-axial Warp-Knitted Composites under Quasi-static and High Strain Rate Loading

The in-plane tensile behaviors of bi-axial warp-knitted(BWK) composites under quasi-static and high strain rates loading were experimentally analyzed in this article. The tensile tests were conducted along warp direction( 0°) and weft direction( 90°) at quasi-static rate of 0. 001 s^(-1) and high strain rates ranging from 1 450 to 2 540 s^(-1),respectively. It is found that the significant strain rate sensitivity can be observed in the stress-strain curves of BWK composites. The fracture morphologies of BWK composites demonstrate that the tensile failure modes are shear failure and fiber breakage under the quasi-static testing condition while interface failure and fibers pullout are at high strain rates.

Effects of Strain Rate and Texture on the Tensile Behavior of Pre-strained NiCr Microwires

The stress–strain behavior and strain rate sensitivity of pre-strained Ni80Cr20（Ni20Cr） were studied at strain rates from 4.8×10^（–4）s^（–1） to 1.1×10^（–1）s^（–1）. Specimens were prepared through cold drawing with abnormal plastic deformation. The texture of the specimen was characterized using electron backscatter diffraction. Results revealed that the ultimate tensile strength and ductility of the pre-strained Ni20Cr microwires simultaneously increased with increasing strain rate. Twinning-induced negative strain rate sensitivity was discovered. Positive strain rate sensitivity was present in fracture flow stress, whereas negative strain rate sensitivity was detected in flow stress values of σ_（0.5%） and σ_（1%）. Tensile test of the pre-strained Ni20Cr showed that twinning deformation predominated, whereas dislocation slip deformation dominated when twinning deformation reached saturation. The trends observed in the fractions of 2°-5°, 5°-15°, and 15°-180° grain boundaries confirmed that twinning deformation dominated the first stage.

Effect of Cooling Rate on the Solidification Behavior and Microstructure of SiC_w/Al-18Si Composites

Al-18Si alloy reinforced with 15%,20% and 25%(volume fraction) SiC whiskers were prepared by squeeze casting technique and the solidification behavior and microstructure of as-prepared composites at different cooling rates were studied by DSC,optical microscope,SEM and TEM.The results show that silicon phase is nucleated on SiC whiskers.With the increase of cooling rate,the degree of undercooling increases in the composites as well as in the alloys.The increase of cooling rate leads to a reduction in the size of eutectic Al-Si and also changes its morphology from short stick to equiaxed.However,the change of primary Si is complex.The primary Si size is refined,and then coarsened with increasing cooling rate.The primary Si morphology of composites changes from agglomerate to stick.

Study on the Dynamic Behavior of Tungsten Alloy at Strain Rates up to 5 000 s^(-1)

The dynamic stress-strain curves of 93% tungsten (W) alloy in the forged state at strain rates up to (5 000 s^(-1)) and in the temperature range from 223 K to 473 K were measured with the split Hopkinson pressure bar (SHPB) technique. Based on the above experimental data a dynamic constitutive equation considering the effects of strain rate, temperature and the special microstructure of such a kind of W-alloy was proposed. The numerical simulation for the experimental process with this constitutive equation was also carried out, the results show that the constitutive relationship constructed in this paper is very satisfactory for representing the dynamic responsive behavior of material..

Dynamic Tensile Behavior and Constitutive Modeling of TC21 Titanium Alloy

The dynamic tensile behaviors of a newly developed Ti-6 Al-2 Sn-2 Zr-3 Mo-1 Cr-2 Nb-Si alloy（referred as TC21 in China） over a wide range of strain rates from quasi-static to dynamic regimes(0.001-1 200 s-1) at different temperatures were experimentally investigated. A split Hopkinson tension bar apparatus and a static material testing system were utilized to study the stress-strain responses under uniaxial tension loading condition. The experimental results indicate that the tensile behavior of TC21 titanium alloy is dependent on the strain rate and temperature. The values of initial yield stress increase with increasing strain rate and decreasing temperature. The effects of strain rate and temperature on the initial yield behavior are estimated by introducing two sensitivity parameters. The phenomenological-based constitutive model, Johnson-Cook model, is suitably modified to describe the rate-temperature dependent constitutive behavior of TC21 titanium alloy. It is observed that the modified model is in good agreement with the experimental data subjected to the investigated range of strain rates and temperatures.

Foraging behavior of the Greater White-fronted Goose(Anser albifrons) wintering at Shengjin Lake: diet shifts and habitat use

Background: The habitat use and foraging behaviors of waterbirds are closely related to the distribution and abundance of their food resources. Reductions in food supply can cause waterbirds to shift their habitats and adjust their foraging behaviors to meet their nutritional requirements and increase fitness. Seasonal withdraw of the water levels in the river-connected lakes in the middle and lower Yangtze River floodplain provides abundant food resources for the wintering Greater White-fronted Goose(Anser albifrons). Sedge(Carex) meadows are critical foraging habitats for herbivorous waterbirds in the hydro-fluctuation belt, which changes with hydrological conditions and climate. This study aimed to examine the behavioral responses of the Greater White-fronted Goose to temporal-spatial changes of food availability in the Sedge meadows.Methods: Fields surveys were carried out at Shengjin Lake from November 2017 to April 2018. According to the phenology of Shengjin Lake, we divided the wintering season into three periods. The food density, minimum temperature, food items, grass height, and number of foraging geese were surveyed, and samples of the foraging behavior were collected. We analyzed the relationship of the foraging behavior and habitat use relative to the food resources, using correlation and linear regression analyses.Results: Along with the temporal-spatial variation and exploitation of food resources, the food abundance and items varied widely among the foraging sites. Over the whole wintering period, the foraging habitat with the highest utilization rate was the meadows, followed by the paddy fields, and then mudflats. Furthermore, the utilization of the meadows showed a bimodal distribution trend, while the paddy fields showed a unimodal trend, and a decreasing trend was seen in the mudflats over the whole wintering period. The results of the generalized linear model showed that the foraging rate was related to the food density and grass height, with a linearly increasing trend during the winter.Conclusions: With the change of food resources in the three habitats, the habitats used by the Greater White-fronted Geese shifted from meadows in the hydro-fluctuation belt to the paddy fields, and then back to the meadows. The time budget for foraging activities increased correspondingly, and there was an increase in the foraging rate to compensate for food shortages.

Kinetic evolutionary behavior of catalysis-select migration

We propose a catalysis-select migration driven evolution model of two-species（A-and B-species） aggregates,where one unit of species A migrates to species B under the catalysts of species C,while under the catalysts of species D the reaction will become one unit of species B migrating to species A.Meanwhile the catalyst aggregates of species C perform self-coagulation,as do the species D aggregates.We study this catalysis-select migration driven kinetic aggregation phenomena using the generalized Smoluchowski rate equation approach with C species catalysis-select migration rate kernel K（k;i,j） = Kkij and D species catalysis-select migration rate kernel J（k;i,j） = Jkij.The kinetic evolution behaviour is found to be dominated by the competition between the catalysis-select immigration and emigration,in which the competition is between JD0 and KC0（D0 and C0 are the initial numbers of the monomers of species D and C,respectively）.When JD0 KC0 〉 0,the aggregate size distribution of species A satisfies the conventional scaling form and that of species B satisfies a modified scaling form.And in the case of JD0 KC0 〈 0,species A and B exchange their aggregate size distributions as in the above JD0 KC0 〉 0 case.

Degradation Behavior of High Chromium Sodium-Modified A356.0-Type Al-Si-Mg Alloy in Simulated Seawater Environment

The effect of multiple-step thermal ageing treatment (MSTAT) on the corrosion characteristics of A356.0-type Al-Si-Mg alloy in simulated seawater has been studied. The MSTAT treatment also consists of Double Thermal Ageing (DTAT- T7), Single Thermal Ageing (STAT- T6), Step- Quenching and Ageing (SQA). The corrosion of the thermal treated samples was characterized by electrochemical Potentiodynamics polarization techniques consisting of linear polarization and chronopotentiometric method using the fit Tafel plot. Generally, from the linear polarization, the corrosion rate decreases at all temperatures with the ageing time. The corrosion behavior of the DTAT and SQA Al-Si-Mg alloy in the simulated seawater showed better resistance than the STAT Al-Si-Mg alloy. Samples in the SQA-STAT have improved corrosion resistance than the SQA-DTAT one. The chronopotentiometric corrosion study of some selected samples indicates a decrease in the corrosion resistance with open circuit potential exposure time. Consequently, the form of corrosion in the studied Al-Si-Mg alloy are slightly uniform and predominantly pitting corrosion as obtained from the SEM study. The pits diameter were found to range from 30-50μm.

Moisture effect on compressive behavior of concrete under dynamic loading

The effect of moisture content upon compressive mechanical behavior of concrete under impact loading was studied. The axial rapid compressive loading tests of over 50 specimens with five different saturations were executed. The technique "split Hopkinson pressure bar"(SHPB) was used. The impact velocity was 10 m/s with corresponding strain rate of 50 s-1. The compressive behavior of materials was measured in terms of stress-strain curves, dynamic compressive strength, dynamic increase factor(DIF) and critical strain at a maximum stress. The data obtained from test indicate that both ascending and descending portions of stress-stain curves are affected by moisture content. However, the effect is noted to be more significant in ascending portion of the stress-strain curves. Dynamic compressive strength is higher at lower moisture content and weaker at higher moisture content.Furthermore, under nearly saturated condition, an increase in compressive strength can be found. The effect of moisture content on the average DIF of concrete is not significant. The critical compressive strain of concrete does not change with moisture content.

Effects of chromium on the corrosion and electrochemical behaviors of ultra high strength steels

The effects of chromium on the corrosion and the electrochemical behaviors of ultra high strength steels were studied by the salt spray test and electrochemical methods. The results show that ultra high strength steels remain martensite structures and have anodic dissolution characteristic with an increase of chromium content. There is no typical passive region on the polarization curves of an ultra high strength stainless steel, AerMet 100 steel, and 300M steel. However, chromium improves the corrosion resistance of the stainless steel remarkably. It has the slowest corrosion rate in the salt spray test, one order of magnitude less than that of AerMet 100 and 300M steels. With the increase of chromium content, the polarization resistance becomes larger, the corrosion potential shifts towards the positive direction with a value of 545 mV, and the corrosion current density decreases in electrochemical measures in 3.5wt% NaCl solutions. Because of the higher content of chromium, the ultra high strength stainless steel has a better corrosion resistance than AerMet 100 and 300M steels.

Structural first failure times under non-Gaussian stochastic behavior

An analytical moment-based method for calculating structuralfirst failure times under non-Gaussian stochastic behavior is proposed. In the method, a power series that constants can be obtained from response moments （skewness, kurtosis, etc.） is used firstly to map a non-Gaussian structural response into a standard Gaussian process, then mean up-crossing rates, mean clump size and the initial passage probability of a critical barrier level by the original structural response are estimated, and finally, the formula for calculating first failure times is established on the assur^ption that corrected up-crossing rates are independent. An analysis of a nonlinear single-degree-of-freedom dynamical system excited by a Gaussian model of load not only demonstrates the usage of the proposed method but also shows the accuracy and efficiency of the proposed method by comparisons between the present method and other methods such as Monte Carlo simulation and the traditional Gaussian model.

Corrosion Behavior of Mg_(65)Cu_(25-x) Zn_xGd_(10)(x=0, 5) Metallic Glass

The effect of substitutional element Zn on corrosion behavior of Mg65Cu25Gd10 glass was investigated. The amorphous structure of Mg65Cu25-xZnxGd10 （x=0,5） alloys were examined by X-ray diffractometry and differential scanning calorimetry （DSC）. The dissolution rates of Mg65Cu25-xZnxGd10 （x=0, 5） metallic glasses in a 5 wt% NaCl solution with pH value of 7 were determined by a hydrogen evolution testing method. The corrosion behavior of these alloys was characterized using dipping tests with 5 wt% NaCl, in combination with electrochemical measurements and scanning electron microscopy （SEM）. Results show that the anti-corrosion ability of Mg65Cu25Gd10 alloy is significantly improved due to the addition of Zn. Possible mechanism responsible for the improvement is discussed.

A solution of the complex Ginzburg-Landau equation with a continuum of decay rates

We prove the existence of a uniform initial datum whose solution decays, in var- ious Lp spaces, at different rates along different time sequences going to infinity, for complex Ginzburg-Landau equation on RN, of various parameters θ and γ.

Social bookmarking behaviors of college students:A survey of Wuhan University Library users

Purpose:To have a better understanding of library users' social bookmarking behaviors,we conducted a survey of college students to examine how much attention they have paid to social bookmarking results,their social bookmarking motivations and behaviors on book sharing sites and in their library's OPAC,and their expectations to their library's social bookmarking service.Design/methodology/approach:A questionnaire survey was conducted to investigate social bookmarking behaviors and motivations of users of Wuhan University Library(WUL) on book sharing sites and in WUL's OPAC.A total of 700 questionnaires were distributed and357 valid questionnaires were retrieved.SPSS was used for data analysis.Findings:The results revealed that there were differences between users' social bookmarking behaviors on book sharing sites and in the Library's OPAC.Users preferred to use tags than add tags on book sharing sites.The main tagging motivation on book sharing sites was for meeting users' specific needs such as collection management and book recommendations.As for the Library,the lack of publicity and promotion of the social bookmarking service led to insufficient use of the Library's service.Due to a lack of knowledge of the social bookmarking service,users did not care about the lectures or publicity campaigns about the Library's social bookmarking service.Research limitations:Because social bookmarking was not common among WUL users,and the questionnaires could be handed out to a limited number of people,it was hard to describe users' social bookmarking behaviors in the Library's OPAC by investigating a sample of 357Library users,and therefore we only investigated users' social bookmarking behaviors on the book sharing sites.Practical implications:The survey results provide insights into library users' social bookmarking behaviors and motivations.The study will help academic libraries improve their social bookmarking service.Originality/value:In spite of growing popularity of social bookmarking sites,little has been known about the social bookmarking behaviors of library users.This study investigated college students' social bookmarking behaviors and motivations,providing suggestions for academic libraries to improve their social bookmarking services.

Effect of strain,strain rate and temperature on workability of AZ80 wrought magnesium alloy

The hot deformation behavior of AZ80 wrought magnesium alloy was studied in the temperature range of 523-673 K and the strain rate range of 0.01-10 s-1 using hot compression tests.Through the flow stresses behavior,the processing maps were calculated and analyzed according to the dynamic materials model.The stable,metastable and unstable regimes were clarified.The optimum processing conditions were suggested as following:the DRX regions in Domain #1-0.25,Domain #2-0.25,Domain #1-0.45,Domain #2-0.45,Domain #3-0.45,Domain #1-0.65 and Domain #1-0.85,and the DRV regions in Domain #3-0.25 and Domain #4-0.45.In each "safe" DRX domain,it is preferable to conduct hot working in the small region around efficiency peak point.The strain has a great influence on the processing maps.The whole area of the "safe" domains increases with the increase of true strain from 0.25 to 0.65,while it decreases with the increase of true strain from 0.65 to 0.85.The results of kinetic analysis reveal that the values of apparent activation energy in all the domains are higher than that for self-diffusion in pure magnesium (135kJ/mol),and the deformation mechanism in all the domains is likely to be cross-slip.

The Impact Compression Behaviors of Silica Nanoparticles—Epoxy Composites

The compressive properties of epoxy with different silica nanoparticles (SiO2 nanoparticles) contents at quasi-static and high strain rates loading were investigated via experiment. This article evaluates the compressive failure behaviors and modes at different SiO2 nanoparticles contents and different strain rates. The results indicated that the stress strain curves were sensitive to strain rate, and the compressive failure stress of composites with various SiO2 nanoparticles contents increased with the strain rates, and it increased along with SiO2 nanoparticles contents and then declined. The compressive failure stress and the compressive failure modes of the composites were apparently different from the change of SiO2 nanoparticles contents.

含钪超高强铝合金在应变速率10^(-3)s^(-1)下的热流变及动态再结晶行为

采用等温热压缩实验和电子背散射衍射分析技术,研究了Al-11.1Zn-2.3Mg-2.0Cu-0.05Sc合金在应变速率10^(-3)s^(-1),变形温度653~733 K条件下的热流变及动态再结晶行为,建立动态再结晶临界应力、临界应变、相对含量、晶粒平均尺寸的拟合方程。结果表明:相关特征参数的拟合方程可以较好地描述含钪铝合金在实验条件范围内的动态再结晶行为。变形温度的升高会增加晶粒内部的取向差,减弱晶粒沿法向的择优取向,有助于动态再结晶的发生。动态回复是含钪铝合金的主要软化机制。随着温度的变化,铝合金微观组织存在不连续动态、连续动态及几何动态三种再结晶机制。

供应链数字化与ESG评级分歧——基于数字化赋能视角

ESG评级分歧作为影响ESG价值链的重要因素,对企业价值有着至关重要的影响,因此备受关注。本文以2013~2022年A股上市公司为样本,采用双重差分法揭示了供应链数字化对ESG评级分歧的影响及其机制。研究发现:供应链数字化显著降低了ESG评级分歧。机制分析表明,供应链数字化通过提升供应链透明度、促进绿色技术创新以及增强企业披露意愿,减少了ESG评级分歧。异质性分析发现,供应链数字化在ESG评级较低、位于非东部地区、国有企业以及董监高无海外经验的企业中,对缓解ESG评级分歧的效果更为显著。进一步分析指出,较低的ESG评级分歧能够抑制企业的“漂绿”行为。本文拓展了供应链数字化的相关研究,并从数字化赋能视角为缓解ESG评级分歧,进而助力企业ESG发展提供了有力的经验证据和启示。