中度球化的20g材质疲劳裂纹的扩展速率

对已超期服役且中度球化的焦炭塔 2 0 g材质在常温下的疲劳裂纹扩展速率da/dN进行了试验研究。试样采用CCT试样 ,有效试样数为 3件 ,用七点递增多项式法求da/dN和Δk ,将 3个试样的da/dN和Δk数据点合在一起进行回归分析。回归时对数据点进行了取舍 ,对前几组数据点的异常 (da/dN随Δk的增大而降低 )作了理论上的分析 ,认为是预制裂纹产生过高的残余拉应力影响了裂纹的正常扩展 ,随着裂纹扩展 ,预制裂纹时产生的残留塑性区被消耗掉 ,疲劳裂纹扩展速率才恢复正常。得到了以Paris公式表达的平面应变da/dN与Δk关系式。将此式与另一个不同实验条件下的关系式作了比较 。

Impacts of Global Warming on Patterns of Temperature Change in China

Global climate change has a wide range ofimpacts,and this paper presents an investigation onhow global warming has changed the relationshipbetween air temperature and latitude & altitude usingthe meteorological data obtained from 160 stations inChina. The investigation indicates that there are verydistinct seasonal differences in patterns of tempera-ture variation as a function of latitude and altitude:avery significant latitude effect in winter and a verysignificant altitude effect in summer. However,withglobal warming,the latitude effect in winter isweakening and the altitude effect in summer isstrengthening. This pattern of change in therelationship between temperature and latitude &altitude is helpful in efforts to reconstruct and explainthe past temperature patterns and variations.

Multiple Cropping Intensity in China Derived from Agro-meteorological Observations and MODIS Data

Double-and triple-cropping in a year have played a very important role in meeting the rising need for food in China.However,the intensified agricultural practices have significantly altered biogeochemical cycles and soil quality.Understanding and mapping cropping intensity in China′s agricultural systems are therefore necessary to better estimate carbon,nitrogen and water fluxes within agro-ecosystems on the national scale.In this study,we investigated the spatial pattern of crop calendar and multiple cropping rotations in China using phenological records from 394 agro-meteorological stations(AMSs)across China.The results from the analysis of in situ field observations were used to develop a new algorithm that identifies the spatial distribution of multiple cropping in China from moderate resolution imaging spectroradiometer(MODIS)time series data with a 500 m spatial resolution and an 8-day temporal resolution.According to the MODIS-derived multiple cropping distribution in 2002,the proportion of cropland cultivated with multiple crops reached 34%in China.Double-cropping accounted for approximately 94.6%and triple-cropping for 5.4%.The results demonstrat that MODIS EVI(Enhanced Vegetation Index)time series data have the capability and potential to delineate the dynamics of double-and triple-cropping practices.The resultant multiple cropping map could be used to evaluate the impacts of agricultural intensification on biogeochemical cycles.

Influence of Climate on Soil Organic Carbon in Chinese Paddy Soils

Soil organic carbon(SOC) is a major component of the global carbon cycle and has a potentially large impact on the greenhouse effect. Paddy soils are important agricultural soils worldwide, especially in Asia. Thus, a better understanding of the relationship between SOC of paddy soils and climate variables is crucial to a robust understanding of the potential effect of climate change on the global carbon cycle. A soil profile data set(n = 1490) from the Second National Soil Survey of China conducted from 1979 to 1994 was used to explore the relationships of SOC density with mean annual temperature(MAT) and mean annual precipitation(MAP) in six soil regions and eight paddy soil subgroups. Results showed that SOC density of paddy soils was negatively correlated with MAT and positively correlated with MAP(P < 0.01). The relationships of SOC density with MAT and MAP were weak and varied among the six soil regions and eight paddy soil subgroups. A preliminary assessment of the response of SOC in Chinese paddy soils to climate indicated that climate could lead to a 13% SOC loss from paddy soils. Compared to other soil regions, paddy soils in Northern China will potentially more sensitive to climate change over the next several decades. Paddy soils in Middle and Lower Yangtze River Basin could be a potential carbon sink. Reducing the climate impact on paddy soil SOC will mitigate the positive feedback loop between SOC release and global climate change.

Temperature Variations in Sidi Bel Abbes during the Last Three Decades

The Mediterranean climate of the Sidi Bel Abbes city in northwestern Algeria has not been the subject of many investigations except some sporadic syntheses reports. However, climate change studying its most important parameters has not, at our knowledge, been the subject of a rigorous study. For this purpose this work intends to gather several temperatures ranging between 1980 and 2006 and find a mathematical model that tells us climate changes following changes in temperature during this time interval. Consequently and undesirably, the results confirm firmly the global greenhouse effect affecting our planet, but what seems rather puzzling is the fact that this warming trend has accelerated over time resulting in a changing climate toward warmer periods, for that reason a likely shift in the region of a semi-arid to tropical or arid regime overall, depending mainly on the evolution of the Azores anticyclone.

Changes in Seasonality in China under Enhanced Atmospheric CO_2 Concentration

Seasonality changes in China under elevated atmospheric CO2 concentrations were simulated using nine global climate models, assuming a 1% per year increase in atmospheric CO2. Simulations of 20th century experiments of season changes in China from the periods 1961-80 to 1981-2000 were also assessed using the same models. The results show that the ensemble mean simula- tion of the nine models performs better than that of an individual model simulation. Compared the mean climatology of the last 20 years in the CO2-quadrupling experiments with that in the CO2-doubling ones, the ensemble mean results show that the hottest/coldest continuous-90-day （local summer/winter） mean temperature in- creased by 3.4/4.5℃, 2.7/2.9℃, and 2.9/4.1℃ in Northeast （NE）, Southwest （SW）, and Southeast （SE） China, respectively, indicating a weakening seasonal amplitude （SA）, but by 4.4/4.0℃ in Northwest （NW） China, indicating an enlarging SA. The local summer lengthened by 37/30/66/54 days in NW, NE, SW, and SE China, respec- tively. In some models, the winter disappeared during the CO2-quadrupling period, judging by the threshold based on the CO2-doubling period. The average of the other model simulations show that the local winter shortened by 42/36/61/44 days respectively, in the previously mentioned regions.

Relationship between air temperature oscillations and solar variability on short and medium time scales

The contemporary science of climate change is increasingly focusing on the temporal and spatial characteristics of temperature oscillations and determining possible underlying causes.In particular,the effect of variations in solar irradiance on the variability of the climate remains a hot topic of debate.Most studies focus on the effects of solar variation on the Earth's climate on long time scales.This study presents the responses of regional climates to solar variations on shorter time scales using two datasets:one for the air temperature in Nanjing and the Greenwich sunspot number,and the other for the air temperature in Shijiazhuang and the United States sunspot number.Employing empirical mode decomposition,both the 11-year quasi-period of the sunspot number and similar periods including approximately 5.5-and 10.5-year cycles of the air temperature in Nanjing and Shijiazhuang are obtained.However,correlation analysis of similar periodic components for the sunspot number and air temperature indicates that changes in the air temperature on short and medium time scales are not linked to solar variations.This is further confirmed by a test of whether a mode component is a stochastic noise signal.Many shorter periods are also found at the 95% confidence level;in particular,the 3.1-year period of the Nanjing air temperature coincides with a previously obtained empirical result.Moreover,no temperature variations on shorter time scales correlate with solar variability.

Liberalization and Reregulation in a Globalized Economy

Building a regulatory regime over its industry challenges the Chinese state in the process of moving towards a modem economy. To what extent has the socialist state intervention in markets been altered along with China＇s integration into the global economy？ Roselyn Hsueh examines China＇s regulatory regime of FDI through the comparison of two industries, telecommunication and textiles and finds an interesting mode of global economic integration that distinguishes China from both the liberal economic model and the East Asian developmental state model. The conclusion is that, even though China has introduced commitments made to the WTO and has liberalized FDI, it only appears to be a more liberal state in that the government has ＂selectively imposed new regulations at the sectoral level, asserting and even tightening control over industry and market development.＂ She further explores the political implication of this bifurcated strategy--＂liberal- ization two-step＂--and argues that introduction of economic competition and tol- erance of private economies and market ideas and norms do not necessarily lead to political change towards a democratic one.

EU and China: Destined to Be Partners in Shaping the Post-Kyoto Regime?

This paper argues that China and the EU are destined to be partners in fighting for a second period of commitments for global climate change governance and shaping the post-Kyoto regime to meet the anticipated challenges of the 21st century. The basic idea backing this argumentation is the assessment that, in comparison with other nations （the United States, Russia, India, Japan and Canada）, Europe and China would have most to lose if the upgrading of the Kyoto Protocol fails; and conversely, they would have most to win if the regime survives in a modernized form and with a more comprehensive application of international binding commitments. This is to say, the EU and China have no choice but to work together if they want to achieve their respective political objectives relating to the issue of global climate change in a less costly and more effective way.