中国人力资本全要素投资效率动态变动及省域差异研究

为评价中国人力资本投资效率,基于DEA-Malmquist生产率指数分析方法,构建人力资本全要素投资效率的测度模型,分析中国31个省、市、自治区2010—2013年人力资本投资的面板数据,对中国人力资本的全要素投资效率进行实证测度,并分析样本年内中国人力资本的全要素投资效率的动态时间序列变动和省域差异情况。研究结果表明:从总体来看,2010—2013年我国人力资本全要素投资效率呈现下降的趋势,平均下降3.2%;从省域来看,安徽人力资本投资效率的改善最好,而吉林的改善最差,技术进步是导致省域差异的主要原因。

中国物流业全要素能源效率动态变动及区域差异分析

物流业是我国能源消耗的重要行业之一,尤其是油料的消耗,位居各行业首位。研究物流业的能源效率,找出其中存在的问题,对于节能减排具有重要的价值。本文基于DEA-Malmquist生产率指数分析方法,构建了物流业全要素能源效率的测度模型。通过分析中国30个省、市、自治区2003-2012年物流业的能源消耗面板数据,对中国物流业的全要素能源效率及技术效率、技术进步、纯技术效率和规模效率指数进行了实证测度,并分析了样本年内中国物流业全要素能源效率的动态变动和区域差异情况。研究发现:2003-2012年中国物流业的全要素能源效率呈现了下降的趋势,下降了2.88%,行业的总体全要素能源效率不高;西部地区物流业的平均全要素能源效率变动最好,达到了0.996,东部次之为0.979,中部最低为0.950;在各地区的对比中,宁夏物流业全要素能源效率的改善最好,青海改善最差,规模效率是导致省域差异的主要原因。文章最后根据中国物流业能源效率的特点,提出了提高该行业能源效率的建议,可以为相关部门的节能减排政策制定提供科学依据。

论科技型创业企业的价值动态变动特性

科技型创业企业作为风险投资的主要投资对象,对其价值的认定就成为风险投资机构的重要工作内容。按照科技型创业企业成长的规律,科技创业企业的成长过程包括种子期、初创期、成长期、扩张期、成熟期。其价值形态的动态体现为:企业技术成果化的价值、企业技术商品化的价值、企业技术市场化(资本化)的价值、企业股权流通性形态价值。科技创业企业的技术经济价值是一个动态实现过程,在实践中对科技企业创业投资宜采用分阶段投资与实物期权相结合的方法。

江西省柑桔害虫发生和消长动态的研究

根据多年观察研究结果和资料的汇集整理 ,将江西省柑桔害虫发生消长动态归纳为9类 。

国际油价波动对中国股市影响及分析

本文以1996年～2009年月度数据为研究样本,结合我国经济运行状况深入研究分析了国际油价波动对中国股市收益的长短期及动态影响。油价波动与我国沪深股市之间存在长期协整关系,随着经济运行状况的改变和时间的推移,油价波动对我国股市影响的动态关系亦随之变动,且油价波动对我国沪深股市的冲击作用主要集中在短期。在油价的行业板块效应研究中发现油价波动与水电、交通运输、公用、采掘、制造、工业、金属和造纸八大板块之间存在协整关系,长期均衡关系对水电、交通运输、采掘和制造板块具有反向调节作用。决策者可根据油价波动状况及相应的政策导向适时调整投资组合以规避油价波动所带来的风险。

中国物流业二氧化碳排放变化驱动因素分析

物流业二氧化碳排放问题是当前我国碳减排工作的重中之重,正确评估各驱动因素在碳排放中的贡献度对于促进行业碳减排意义重大。可基于LMDI分解技术,构建物流业二氧化碳排放变化驱动因素分解分析模型,将物流业碳排放变化驱动因素分解为碳排放因子效应、能源结构效应、能源强度效应、物流产出效应、经济发展效应、人口规模效应等六个方面,并利用2003—2014年我国30个省市区物流业面板数据进行实证分析。研究样本年内各驱动因素动态变动和区域差异情况可以发现,我国物流业二氧化碳排放强度基本呈逐年上升趋势;经济发展效应是物流业二氧化碳排放持续高速增长最主要的驱动因素,物流业产出的提高是抑制二氧化碳排放增长最主要的驱动因素;东部地区能源结构的变化对物流业二氧化碳排放有抑制作用,而中西部地区能源结构需要进一步优化。此外,对各省市区情况的分析表明,广西能源结构效应表现最好,宁夏能源强度效应表现最好,江西物流产出效应表现最好,河北经济发展效应表现最好,四川人口规模效应表现最好。

Dynamic globularization kinetics during hot working of TA15 titanium alloy with colony microstructure

The dynamic globularization kinetics of TA15（Ti-6Al-2Zr-1Mo-1V） titanium alloy with a colony α microstructure during deformation at temperature range of 860-940 ℃ and strain rate range of 0.01-10 s-1 was quantitatively studied through isothermal compression tests.It is found that the dynamic globularization kinetics and the kinetics rate of TA15 are sensitive to deformation parameters.The dynamic globularized fraction increases with increasing strain,temperature but decreasing strain rate.The variation of globularized fraction with strain approximately follows an Avrami type equation.Using the Avrami type equation,the initiation and completion strains for dynamic globularization of TA15 were predicted to be 0.34-0.59 and 3.40-6.80.The kinetics rate of dynamic globularization increases with strain at first,then decreases.The peak value of kinetics rate,which corresponds to 20%-33% globularization fraction,increases with increasing temperature and decreasing strain rate.

Numerical simulation of dynamic surface deformation based on DInSAR monitoring

Differential interferometric synthetic aperture radar （DInSAR） technology is a new method to monitor the dynamic surface subsidence. It can monitor the large scope of dynamic deformation process of surface subsidence basin and better reflect the surface subsidence form in different stages. But under the influence of factors such as noise and other factors, the tilt and horizontal deformation curves regularity calculated by DInSAR data are poorer and the actual deviation is larger. The tilt and horizontal deformations are the important indices for the safety of surface objects protection. Numerical simulation method was used to study the dynamic deformation of LW32 of West Cliff colliery in Australia based on the DInSAR monitoring data. The result indicates that the subsidence curves of two methods fit well and the correlation coefficient is more than 95%. The other deformations calculated by numerical simulation results are close to the theory form. Therefore, considering the influence, the surface and its subsidiary structures and buildings due to mining, the numerical simulation method based on the DInSAR data can reveal the distribution rules of the surface dynamic deformation values and supply the shortcomings of DInSAR technology. The research shows that the method has good applicability and can provide reference for similar situation.

Hot deformation behavior of Al-Zn-Mg-Cu-Zr aluminum alloys during compression at elevated temperature

The hot compression tests of Al-Zn-Mg-Cu-Zr aluminum alloys （7056 alloy and 7150 alloy） were performed in a temperature range from 300 to 450 °C and at strain rate range from 0.01 to 10 s-1. The results show that the true stress-true strain curves exhibit a peak stress at a critical strain, then the flow stresses decrease monotonically until high strains, showing a dynamic flow softening. The peak stresses depend on the temperature compensated strain rate, which can be represented by the Zener-Hollomon parameter Z in the hyperbolic-sine equation with hot deformation activation energy of 244.64 kJ/mol for 7056 alloy and 229.75 kJ/mol for 7150 alloy, respectively, while the peak stresses for the former are lower than those for the latter under the similar compression condition. The deformed microstructures consist of a great amount of precipitates within subgrains in the elongated grains at high Z value and exhibit well formed subgrains in the recrystallized grains at low Z value. The smaller subgrains and greater density of fine precipitates in 7150 alloy are responsible for the high peak stresses because of the substructural strengthening and precipitating hardening compared with 7056 alloy.

Analysis and Experimental Identification of Torsional Dynamic Characteristics of Hydrodynamic Torque Converter

The subsection linear torsional model of hydrodynamic torque converter was established and further simplified. According to the identification theory, the frequency characteristic was achieved with the Matlab/ Ident toolbox. Then parametric model was established by adopting the subsection linearization method, and the damp value was estimated. The curve and function of damp changing with speed ratio was also established by fitting. In order to validate the identification results, the experimental output was compared with the output of the model in which torque was chosen as input signal and speed as output signal in Matlab/Ident toolbox. It was shown that model output is in good agreement with experimental output.

Dynamic recovery and dynamic recrystallization of NiTi shape memory alloy under hot compression deformation

Mechanical behavior of nickel？titanium shape memory alloy（NiTi SMA） under hot deformation was investigated according to the true stress—strain curves of NiTi samples under compression at the strain rates of 0.001-1 s-1 and at the temperatures of 600？1000℃.Dynamic recovery and dynamic recrystallization of NiTi SMA were systematically investigated by microstructural evolution.The influence of the strain rates,the deformation temperatures and the deformation degree on the dynamic recovery and dynamic recrystallization of NiTi SMA was obtained as well.NiTi SMA was characterized by the combination of dynamic recovery and dynamic recrystallization at 600℃ and 700℃,but the complete dynamic recrystallization occurred at other deformation temperatures.Increasing the deformation temperatures or decreasing the stain rates leads to larger equiaxed grains.The deformation degree has an important influence on the dynamic recrystallization of NiTi SMA.There exists the critical deformation degree during the dynamic recrystallization of NiTi SMA,beyond which the larger deformation degree contributes to obtaining the finer equiaxed grains.

Rate controlling mechanisms in hot deformation of 7A55 aluminum alloy

The hot deformation behavior of 7A55 aluminum alloy was investigated at the temperature ranging from 300 ℃ to 450 ℃ and strain rate ranging from 0.01 s-1 to 1 s-1 on a Gleeble-3500 simulator. Processing maps were established in order to apprehend the kinetics of hot deformation and the rate controlling mechanism was interpreted by the kinetic rate analysis obeying power-law relation. The results indicated that one significant domain representing dynamic recrystallization （DRX） existed on the processing maps and lying in 410-450 ＆#176;C and 0.05-1 s-1. The conclusions of kinetic analysis correlated well with those obtained from processing maps. The apparent activation energy values calculated in the dynamic recrystallization （DRX） domain and the stability regions except dynamic recrystallization （DRX） domain were 91.2 kJ/mol and 128.8 kJ/mol, respectively, which suggested that grain boundary self-diffusion and cross-slip were the rate controlling mechanisms.

Dynamic recrystallization kinetics of as-cast AZ91D alloy

The flow behavior and dynamic recrystallization（DRX） behavior of an as-cast AZ91 D alloy were investigated systematically by applying the isothermal compression tests in temperature range of 220-380 ℃ and strain rate range of 0.001-1 s^-1.The effect of temperature and strain rate on the DRX behavior was discussed.The results indicate that the nucleation and growth of dynamic recrystallized grains easily occur at higher temperatures and lower strain rates.To evaluate the evolution of dynamic recrystallization,the DRX kinetics model was proposed based on the experimental data of true stress-true strain curves.It was revealed that the volume fraction of dynamic recrystallized grains increased with increasing strain in terms of S-curves.A good agreement between the proposed DRX kinetics model and microstructure observation results validates the accuracy of DRX kinetics model for AZ91 D alloy.

Deformation behavior of Ti-5Al-2Sn-2Zr-4Mo-4Cr alloy with two initial microstructures during hot working

The effects of initial microstructure on the flow stress, strain rate sensitivity （m）, strain hardening exponent （n）, apparent activation energy （Q） for deformation of Ti-5Al-2Sn-2Zr-4Mo-4Cr alloy were investigated using isothermal compression tests. Results show that the alloy with Widmanst-tten alpha plates shows a higher peak stress and flow softening. Additionally, the alloy with equiaxed primary alpha exhibits an early yield drop at or above 810 ℃ and at strain rates of 0.1-5.0 s^-1. In the strain range of 0.5-0.7,m of the alloy with equiaxed primary alpha is found to be larger at 0.01 s^-1 and lower deformation temperatures. This phenomenon could be reasonably explained based on the microstructure evolution. The strain has a significant effect onn of the alloy with Widmanst-tten alpha plates, which is attributed to platelet bending/kinking and dynamic globularization ofα phase. In the strain range of 0.15-0.55,Q of the alloy with Widmanst-tten alpha plates is larger.

Structural changes and volatility correlation in nonferrous metal market

The GARCH and DCC-GARCH models are used to study the volatility aggregation and dynamic relevance of China’s three kinds of nonferrous metals （copper, aluminum and zinc） pricesincorporating structural changes. The results show that copper, aluminum and zinc returns have many structure breaks points, and nonferrous metals have the greatvolatilityrisk during financial crisis. From the resultsof GARCH with and without structural changes,it isfoundthat the volatility clustering of single nonferrous metal is overvalued when ignoring the structural mutation, and the return of aluminum isthe most overvalued, indicating that aluminum market is more susceptible to external shock.Furthermore,it is also foundthatdynamic volatility correlation exists in the three prices of nonferrous metals, and the structural changes have no significant effect on the volatility correlation of thethree nonferrous metals.

Flow behavior and microstructure evolution of 6A82 aluminium alloy with high copper content during hot compression deformation at elevated temperatures

The flow behavior and microstructure evolution of 6A82 aluminum alloy (Al?Mg?Si?Cu) with high copper content were studied on a Gleeble?1500 system by isothermal hot compression test in the temperature range from 320 to 530 °C and the strain rate range from 0.001 to 10 s?1. The results reveal that the flow stress of the alloy exhibits a continuous flow softening behavior at low temperatures of 320?390 °C, whereas it reaches steady state at high temperatures (≥460°C), which are influenced greatly by the Zener?Hollomon parameter (Z) in the hyperbolic sine with the hot deformation activation energy of 325.12 kJ/mol. Microstructure characterizations show that prominent dynamic recrystallization and coarsening of dynamic precipitation may be responsible for the continuous flow softening behavior. Due to deformation heating at high strain rates (≥1 s?1), dynamic recrystallization is more prominent in the specimen deformed at 530 °C and 10 s?1 than in the specimen deformed at 460 °C and 0.1 s?1 even though they have very close lnZ values.

Characterization of dynamic microstructure evolution during hot deformation of Al-4.10Cu-1.42Mg-0.57Mn-0.12Zr alloy

The Al?4.10Cu?1.42Mg?0.57Mn?0.12Zr alloy was compressed to different strains at deformation temperature of 300 oC and strain rate of 10 s?1 on Gleeble?1500 system. The dynamic complex microstructures evolutions were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The true stress?true strain curves exhibited a peak stress at critical strain, after which the flow stresses decreased monotonically, showing a dynamic flow softening. As the strain increased, the dislocation tangled to cell structure and sub-grain structure, which indicated the occurrence of dynamic recovery during deformation. Dynamic precipitations ofS (Al2CuMg),θ (Al2Cu) and Al3Zr phase were accelerated and coarsened by deformation. ContinuousS phases precipitated in the Al matrix and discontinuousS phases were found to be nucleated near the Al3Zr phase and at the sub-grain boundary. The flow softening mechanism was resulted from the reduction of dislocation density which attributed to dynamic recovery and precipitates coarsening.

Status and distribution changes of the endangered Green Peafowl (Pavo muticus) in China over the past three decades (1990s-2017)

Background： Understanding the changes in population dynamics, including demographics, distribution and threats is essential for species status assessing.The endangered Green Peafowl （Povo muticus） has experienced sharp population declines and d stribution range diminishing both in China and Southeast Asia. Field population surveys have not been conducted in China since the 1990s, which hindered conservation planning and decision-making.Methods： With interview and line transects methods, we figured out the population and distribution changes of Green Peafowl across its historical ranges over the past three decades in China during 2014-2017.Results： The Green Peafowl once habituated in 54 counties in China. Nearly 60% of the distribution counties were lost in the past three decades, with the left 22 counties distributed in central, southern and western Yunnan, SW China. Population decrease detected in all distribution areas except for Shuangbai and Xinping county where more than 60% of the total population is located. Only about 30% of the former bird population were recorded with the same interviewing method as 20 years ago.Three birds, 1 carcass, 6 calls and 12 footprints were detected along the 865 km line transects, indicating extremely low encounter rate of Green Peafowl in field. Sharp decreases in flock sizes were also detected, from 8-20 birds per flock in the 1990s to 3-5 birds at present. Poaching and habitat conversion are two widespread and long-lasting threats, while poison tion affect regional population＇s survival. Large flocks of 18 ng caused mortality in the past and hydropower construc -27 birds were discovered in the field, which increases our confidence of population recovery of this endangered pheasant in China.Conclusions： Only interviewed bird number and counts based on line transects were presented in this study, without further population estimation due to limitation of the data sets. Although the actual population of this cryptic bird must be underestimated, dramatic population declines and distribution concentrations of the endangered Green Peafowl occurred over the past 30 years in China undoubtedly.

Experiment of dynamic property and transient magnetic effects of coal during deformation and fracture

Combining separated SHPB test device of Ф50 mm with ZDKT-type 1 transient magnetic resonance test system, long drop bar of 400 mm was used to impact coal specimens at four different speeds： 1.275, 3.287, 6.251, and 7.404 m/s. The change in waveform, the dynamic mechanical properties, and the generated effect of transient field during the coal deformation and fracture under the loads were discussed and analyzed. While magnetic signals during the coal fracture firstly needed EEMD, decomposition then had a FFT with Data Demon. The main results of the experiment are the following： the main frequency of magnetic signals was between 220 and 450 kHz and the instantaneous frequency during the damage of coal would have the instantaneous jump.

Pseudo-dynamic analysis of overturning stability of retaining wall

A new method was presented to determine the safety factor of wall stability against overturning based on pseudo-dynamic approach. In this time-dependent method, the actual dynamic effect with variation of time and propagation of shear and primary wave velocities through the backfills was considered. Planar failure surface was considered behind the retaining wall. The results were compared with those obtained from Mononobe-Okabe theory. It is found that there is a higher value of safety factor by the present dynamic analysis. The effects of wall inclination, wall friction angle, soil friction angle and horizontal and vertical seismic coefficients on the overturning stability of retaining wall were investigated. The parametric study shows that both horizontal and vertical seismic accelerations have decreasing effect on the overturning stability of retaining wall.