Search

A series of plastic materials for an organs injury stress assessment model use were prepared using a blend of potassium stearate (PS), sodium stearate (SS), polyvinyl alcohol (PVA) and paraffin liquid (PL) at various weight ratios. The mechanical properties of the materials were investigated via a compression test using Instron, and the results indicated that the PS/SS/PVA/PL blend with a weight ratio of 0·35∶0·35∶0·02∶0·28 had superior plastic deformation properties. The PS/SS/PVA/PL blend’s weight ratio of 0·35∶0·35∶0·02∶0·28 was characterised by using Fourier transform infrared spectroscopy, a scanning electron microscope and differential scanning calorimetry. For a comparison, blend samples of PS/SS/PVA/PL with weight ratios of 0·68∶0∶0·2∶0·30 and 0∶0·68∶0·2∶0·30 were measured using the same methods. The results show that the plastic deformation mechanism is due to the optimal combination of weight ratio of the PS and the SS, and that the carbon chain in the PVA is a backbone of the slip function.

Many previous studies indicate that land-use/-cover change (LUCC) has effects on hydrological processes at the catchment level. The spatial pattern of LUCC (LUSP) may have different influences on hydrological processes. In this article, a mountainous catchment with different micro-topographic and micro-climatic types in the south-west of China was selected to study the LUSP and its impacts on annual sediment charge (ASC). Remotely sensed images from the Landsat Multi-Spectral Scanner (MSS), the Thematic Mapper (TM), the Enhanced Thematic Mapper Plus (ETM+) and the China–Brazil Earth Resource Satellite (CBERS) were used to retrieve land-use/-cover conditions for the past three decades. The multispectral operational method for TM/ETM+ and spectral threshold methods for MSS and CBERS were employed to retrieve the topographic shadows. LUCC was analysed in different topographic areas, proximities to streams and micro-climate areas. The impacts of LUCC on ASC were then calculated and analysed by the weights of ...

Environmental impacts of metropolitan Shanghai's growth, sporadic during the 1960s-1980s and rapidly accelerating in the 1990s, is clearly revealed by integrating remotely sensed images with data sets in a geographical information system. This examination first considers the methodology of using multi-sensor data to assess land use and land cover changes. Images utilized vary by scale and resolution, number of spectral bands, and classification schemes. Patterns of land use over this time period is then examined in relation to shifts in the political economy and the resulting changes in the density of population settlement and occupations in urban and rural areas. The conclusion reiterates the usefulness of remotely sensed data in a geographic information system for policy formulation designed to improve the environment of this giant metropolis in the vanguard of China's development.

Palmer's Drought Severity Index (PDSI) is used to represent moisture conditions in the southeastern United States. Temporal trends in annual PDSI for 53 climate divisions in the region are examined for the period 1895 to 1988. Spearman's rank correlation reveals that 19 climate divisions have increasing trends in annual PDSI at the 0.05 significance level, changing towards a wetter condition during the study period. There is no division with a significant decreasing trend. Such temporal changes also display a welldefined spatial pattern. All but one of the divisions with significant increasing trends are located in the southwestern part of the region, centered at Alabama. Climate divisions in Alabama have experienced the most consistent change towards a wetter condition. The increasing rates in the annual PDSI during the study period range from 0.021/year to 0.037/year. Further analysis indicates that the increases in annual PDSI are mostly the result of increasing annual precipitation. Introduction Recent climatic fluctuations have attracted a great attention. Many studies focus on the temporal variation of climatic variables, such as temperature and precipitation. In the southeastern United States, temporal variations in temperature have been discussed by several workers. Although there is a general warming trend corresponding to the increase of CO2 in the atmosphere since the turn of the century, the temperature in the southeast has been characterized by a cooling trend since the 1930s with more colder winters lately (Barnett 1983, McCabe 1988, Skeeter 1985, Suckling 1986 and 1988). Studies on precipitation are fewer than that on temperature. There is probably a slight increase in precipitation in the southeastern United States. For example, Plummer (1983) found an increase in statewide precipitation for Georgia. Howarth (1989) also found an increase in statewide precipitation for Kentucky. However, changes in precipitation are often highly localized Geografiska Annaler · 75 A (1993) · 1-2 and few studies have been able to generalize a regional pattern. Recently, several studies are focused on droughts in the southeastern United States, probably prompted by the severe droughts occurred in the 1980s (Eder et al. 1987, Henry and LeBoutillier 1990, Soul6 and Meentemeyer 1989). Severe droughts have been recorded in the 1930s, 1950s, and especially the 1980s. 1981 was a very dry year for Georgia and South Carolina (Carter 1983). In 1986, the southeast was hit by one of the worst droughts in the century (Karl and Young 1987). This drought was ranked as unprecedented for the past 277 years in the southern Appalachian Mountains (Cook et al. 1988). The southeast was affected again in 1988 by a drought covering a large portion of the United States (Soule and Meentemeyer 1989). 1990 saw another dry year for Georgia and Florida (LeComte 1991). These severe droughts, particularly when occurring in consecutive years, are great threats to agriculture in the region, causing crop failures and lower income to farmers. Severe droughts also cause water supply shortage in urban areas where surface water is the main source, such as Atlanta. Furthermore, frequent wild fires are often associated with droughts (Izlar 1984). After 3 years of consecutive drought years in south Florida, the Everglades were on fire in early 1990. The fire continued for more than 2 months and burned more than 20,000 acres (LeComte 1991). A wild fire broke out later in 1990 in the Okefenokee Swamp National Wildlife Refuge in south Georgia and swept over more than 5000 acres in just two days. The refuge spent $6.6 million to fight the fire (Leavenworth 1991). Palmer's Drought Severity Index (PDSI) has been widely used in regional climatic studies because it summarizes the effect of changing temperature and precipitation. Although it was originally designed to represent drought conditions, its val

A detailed analysis of weathering-pit distribution on Georgia's Stone Mountain granite dome reveals a complex relationship between pit size and density, compared with slope aspect and angle. The uniform nature of the lithology provides an ideal natural laboratory for the analysis of weathering pits. Through the random establishment of 32 dome-encircling, ten-by-ten meter study plots within an elevational range from 610 to 650 meters, the distribution, size, aspect, slope and lithology of pit features were mapped, measured, and analyzed. Thematic maps were used in the visual representation of pit distribution and dimension data. Correlation coefficients, ANOVA, and multiple regression analyses were utilized to determine the relationships of these variables. Pits showed a dimensional and density increase toward a southwestern aspect as well as a dimensional and density increase with decreasing slope angle. Greatest pit dimensions were found at approximately the 200° N azimuth. These findings lead the author...