On size and boundary effects in scaled model blasts spatial problems

This paper addresses size and boundary effects on wave propagation, fracture pattern development and fragmentation in small scale laboratory-size specimens for model blasting. Small block type specimens are centre-line loaded by linear explosive charges and supersonically detonated. Using elastic wave propagation theory and fracture mechanics it is shown that the type of boundary conditions which prevail at the outer boundary of the cylinder control the extension of bore-hole cracking and fragmentation within the body of the cylinder. In the case of a composite block where a cylindrical core of different material is embedded, the level of fracturing and fragmentation is controlled by the separation of the interface which in turn depends on the relative dimensions of the core and the block. The most important parameter is the ratio between the length of the pulse (space-wise or time-wise) and the characteristic dimensions of the models, i.e. in this case the dimensions of the core and the mantel. Stress wave superposition effects occur in the corner sections of the mantel. Theoretical results are in good agreement with recent experimental findings.     

烟台城市空间扩展的过程与机制研究

城市空间扩展是城市中心的经济、社会、政治和文化等人文因素和土地利用、地貌形态等自然因素在地域上的向外推进与扩散。在遥感影像和统计年鉴等资料的支持下,以烟台市为例,探讨了城市空间扩展的过程与动力机制。烟台市在建国后相当一段时期内城市空间扩展缓慢,1985年城市化开始加速,进入21世纪后城市空间快速扩展;其城市空间扩展机制受自然条件、经济发展水平、交通状况、国家政策与城市规划等诸多因素影响。     

Macro- and trace-element concentrations in leaves and roots of Phragmites australis in a volcanic lake in Southern Italy

Cr, Cu, Fe, K, Mg, Mn, N, Ni, Pb, S, V and Zn concentrations were determined during a whole seasonal cycle in leaves and in water and sediment roots of the aquatic macrophyte Phragmites australis (Cav.) Trin. ex Steudel from three sites in the Lake Averno (Naples, Italy), a volcanic lake contaminated by trace elements. At the beginning of the research, elemental analysis was also performed on lake sediments, that showed different trace-element concentrations depending on the sites.     

Macro- and micro-mechanical relationship of the anisotropic behaviour of a bonded ellipsoidal particle assembly in the elastic stage

Acta Geotechnica - In this paper, we study analytically the three-dimensional (3D) stress–strain relationships at the elastic stage with regard to the anisotropic granular materials composed...     

Siltstone from Southern Patagonia: Its Source and Archaeological Artifact Distribution in Santa Cruz Province,Argentina

Hunter‐gatherer mobility and spheres of interaction are important characteristics worthy of investigation in Patagonian archaeology. One way to approach these is by studying the distribution of lithic archaeological materials. Siltstone (limolite) artifacts are found along the western strip of southwestern Patagonia, Argentina. Based on geomorphological studies and the high density of archaeological material, a source was located along the western margin of Cardiel Lake. Neutron activation analysis of samples from the source and archaeological sites in several neighboring basins allowed us to model its circulation. Siltstone's archaeological distribution indicates that its regional circulation had a southerly direction dating from the early Holocene. This southern vector shows an important difference when compared to the distribution of obsidian from Pampa del Asador, which has a broader circulation pattern. This could be related to a greater availability of high‐quality lithic materials north of the siltstone source. This work also contributes to the construction of a lithic source database for southern Patagonia.     

Discrete element simulation of the effect of particle size on the size of fracture process zone in quasi-brittle materials

Experimental tests performed on quasi-brittle materials show that a process zone develops ahead of a crack tip. This zone can affect the strength and the deformation pattern of a structure. A discrete element approach with a softening contact bond model is utilized to simulate the development of the fracture process zone in the three-point bending tests. Samples with different dimensions and particle sizes are generated and tested. It is shown that as the material brittleness decreases, the width of the process zone becomes more dependent on the specimen size. Furthermore, the increase in the particle size, results in increase in the width of the process zone. A dimensional analysis together with the numerical results shows that the width of process zone is a linear function of particle size (radius). This finding is discussed and compared with published experimental data in the literature.     

Beyond the census: a spatial analysis of health and deprivation in England

Whilst the UK is planned to have a census in 2021, it may well be the last and there is official acknowledgement that the country’s statistical system should be enhanced by greater use of administrative data. Thus, there is a pressing need to understand whether alternative data sources are fit for social science purposes. This study assesses the potential of utilizing administrative statistics for investigating the relationships between health and socioeconomic distributions for small areas; a type of study regularly carried out using census data. Pairs of administrative measures of health and deprivation indicator variables are compared with census equivalents for lower super output area geographies in England in 2001. The administrative datasets are then used to derive health measures and deprivation indexes for the time points 2001, 2006 and 2010. Inequalities in health are then analysed using administrative data derived area measures with health found to be poorer in areas with socioeconomic disadvantage. Overall, the administrative datasets used here reveal very similar patterns of health and deprivation to the decennial census suggesting they are viable alternatives and have great potential to enhance the country’s statistical system given their availability outside census years.     

HIV and AIDS in Africa: a geographic analysis at multiple spatial scales

This study offers an alternative method rooted in GIS techniques and spatial analysis to estimate HIV/AIDS prevalence over space from an incomplete surveillance data set and explain the variation of those estimates. The results clearly show that the HIV/AIDS epidemic is complex and that it is interconnected with other geographic, historical, economic and cultural phenomena which help explain its spatial spread and variation. The regression models which were developed in this paper illustrated that variables which measure the historical context of colonialism such as resource exploitation and labor migration, gender, culture, contemporary global forces, poverty and disease burden have all contributed variously to the rapid spread of this disease both in space and time. The policy implication is that concentrating on behavior change or therapy alone may not turn the epidemic around. The attack needs to be multifaceted and interdisciplinary taking into consideration the context and the economic and social realities at multiple spatial scales.     

Explaining foreign diplomatic presence in the U.S. with spatial models: a liberal spatial perspective

This paper examines the effect of economic interdependence, intergovernmental organizations, political freedom, and spatial relationship on foreign diplomatic presence in the U.S. from 1980 to 2000. Spatial perspective is largely missing in the mainstream international theories. Spatial relationship has three measures: spatial proximity measured as distance, spatial dependency measured as neighborhood effect, and spatial heterogeneity measured as regional effect. We found that the effect of economic interdependence is directional. The U.S. sensitivity to foreign trade rather than foreign sensitivity to trade with the U.S. explains much of the variation in the foreign diplomatic presence in the U.S. Spatial effect is mainly manifested as spatial dependency; the effects of geographic proximity and geographic regions on foreign diplomatic presence are, however, mild. Spatial dependency in the variation of foreign diplomatic presence in the U.S. could not be well explained by the liberal perspective without using the spatial model.

Observed oil and gas field size distributions: A consequence of the discovery process and prices of oil and gas

If observed oil and gas field size distributions are obtained by random samplings, the fitted distributions should approximate that of the parent population of oil and gas fields. However, empirical evidence strongly suggests that larger fields tend to be discovered earlier in the discovery process than they would be by random sampling. Economic factors also can limit the number of small fields that are developed and reported. This paper examines observed size distributions in state and federal waters of offshore Texas. Results of the analysis demonstrate how the shape of the observable size distributions change with significant hydrocarbon price changes. Comparison of state and federal observed size distributions in the offshore area shows how production cost differences also affect the shape of the observed size distribution. Methods for modifying the discovery rate estimation procedures when economic factors significantly affect the discovery sequence are presented. A primary conclusion of the analysis is that, because hydrocarbon price changes can significantly affect the observed discovery size distribution, one should not be confident about inferring the form and specific parameters of the parent field size distribution from the observed distributions.This paper was presented at Emerging Concepts, MGUS-87 Conference, Redwood City, California, 13–15 April 1987.     

Composite methodology for interpreting sediment transport pathways from spatial trends in grain size: A case study of the Lithuanian coast

To achieve a more robust interpretation of sediment conditions and transport based on grain size, this study combines the perspectives of two different interpretation techniques that have been developed separately and applied in the literature: (i) ‘grain size trend analysis’ interprets changes between interrelated sampling sites assuming that sediment in the direction of transport should become either coarser, better sorted and more positively skewed, or finer, better sorted and more negatively skewed; and (ii) the ‘population anomalies’ method, which estimates the balance between erosion and accumulation processes at each sampling site based on individual site deviations compared with average values for grain‐size parameters in the area of interest. The simultaneous use of both approaches enables sedimentological conditions and transport alternatives to be distinguished. This improvement is necessary because site‐specific changes and general textural trends provide information that complements the strengths and weaknesses of each perspective. The methods are implemented here using two‐dimensional Geographic Information System tools and illustrated for the Lithuanian coast. Grain‐size characteristics of 712 surface samples of sandy sediments are used to interpret sediment transport pathways and predominant sedimentological conditions in the Lithuanian coastal zone. In general, coast‐parallel sediment transport dominates the entire investigation area, although wave‐induced movement perpendicular to the coastline is inferred in the shallow nearshore zone. The deepest areas offshore are characterized by sea floor erosion in the north, whereas an accumulation zone occurs in the relatively deep central part of the study area.     

Floods in Greece, a statistical and spatial approach

Flooding is one of the most important types of disasters in southern Europe recording many victims and extended damages over the last century. The increased pressure for urban expansion together with the high population density has increased flood risk considerably in the region. Greece is not an exception in this regime, having a very rich flooding record since the ancient times. In this work, an extensive catalogue of flooding phenomena during the last 130?years in Greece has been compiled based on numerous sources. Based on this record the temporal and spatial distribution of flood events and victims was examined. In total, 545 events were identified, causing 686 human casualties and inflicting extensive damage across the country. Results showed seasonality patterns with more events clustering in November. They also showed that urban environments tend to present a higher flood recurrence rates than mountainous and rural areas. An increasing trend in reported flood event numbers during the last decades was discovered, even though the number of human casualties remains relatively stable during the same period. Moreover, spatial patterns were identified highlighting areas and administrational entities with higher flood recurrence rates across the country.     

Desert Pavement Disturbance and Artifact Taphonomy: A Case Study from the Eastern Libyan Plateau,Egypt

Accretionary desert pavements on the eastern Libyan Plateau of central Egypt support a rich Middle and Upper Paleolithic artifact assemblage exhibiting intensive blank production and minimal tool production. These assemblages appear to be in primary context with numerous examples of lithic refits showing on‐site lithic production. However, the smallest (length ≤2.5 cm) archaeological fragments are recovered at a much lower rate on this desert pavement surface than expected given comparable data from lithic assemblages in cave and shelter contexts in France. Excavation of archaeological contexts on the Libyan Plateau reveals the loss of small artifact fragments into the subsurface due to aeolian accumulation of silts, whereas geomorphic examination of desert pavement surfaces suggests a potential for relatively isolated bioturbation as a source of lateral and vertical disturbance of desert pavement surfaces over small areas. Archaeologists should be aware of the potential for long‐term assemblage stability as well as small artifact burial in surficial desert pavement contexts.     

Temporal and spatial evaluation of environmental noise in urban area: a case study in Iran

Environmental noise pollution is a disrupting factor in the urban areas which can lead to adverse health effects, behavior and quality of life. Present study was carried out in Tabriz (Iran) and aimed to achieve a real condition of noise pollution. Thirty-five measurement stations were selected, and noise levels were recorded. The equivalent noise level in (A) frequency weighting network, route-mean-square sound pressure level, minimum sound pressure level, maximum sound pressure level and noise pollution level were computed as applicable indices. Temporal and spatial variability of these noise indices were plotted by Arc GIS. Public awareness about the noise pollution was assessed through interview. Mixed model and pairwise comparisons were used for comparison of noise indices based on stations and times. It was found that noise levels were significantly different and higher than permissible levels at most stations, especially at heavily travelled crossroads and squares. Mean equivalent noise level for morning, noon, afternoon and night was 71.35 ± 7.49, 71.63 ± 4.90, 70.67 ± 4.52 and 68.74 ± 5.22 dB(A), respectively. The noise indices of all stations and measurement times had significant difference (p value = 0.028 and 0.019, respectively). It was observed that in normal traffic, the highest sound levels are produced by buses, trucks and motorbikes due to low-technology engines. Using the horn was the first reflex of the most drivers. A main part of the noise pollution problem of the studied city can be attributed to driving culture and non-compliance with traffic laws.     

Diet of winter flounder in a New Jersey estuary: Ontogenetic change and spatial variation

Juvenile and adult winter flounder,Pseudopleuronectes americanus Walbaum (Pleuronectidae), from the Navesink River and Sandy Hook Bay, New Jersey, U.S., were examined for ontogenetic, seasonal, and spatial variation in dietary content. Fish (n=1291 non-empty) were placed by cluster analysis of dietary content into three size groups: 15–49, 50–299, and ≥300 mm total length. Clear ontogenetic patterns were revealed, in particular the disappearance of calanoid copepods from the diet as fish grew >50 mm and an increase in number of taxa in the diet with growth. Fish in size group 1 fed upon spionid polychaetes, the calanoid copepodEurytemora affinis, and ampeliscid amphipods. Fish in size group 2 added various species of polychaetes, amphipods, and siphons of the bivalveMya aremaria to their diets. Size group 2 was present during all months of the survey, but only minor seasonal differences in their diet were apparent. One obvious change was the increase in consumption of the shrimpCrangon septemspinosa in summer and fall. Size group 3 fish, collected mainly in fall, ate large volumes ofM. arenaria and glycerid polychaetes. Cluster analysis showed a largescale spatial pattern in diet among fish of size group 1, related to the presence ofE. affinis in winter flounder diets in the river and a marsh cove in the bay. Small-scale spatial differences in diets of fish in size group 2 were possibly related to prey distribution.     

Phytoplankton biomass in a subtropical estuary: Distribution,size composition,and carbon:Chlorophyll ratios

The seasonal pattern of phytoplankton biomass (chlorophyll and particulate organic carbon) and the salinity-related pattern of phytoplankton biomass and size composition were determined in Apalachicola Bay, Florida, throughout 2004. Phytoplankton biomass was highest during summer and lowest during winter. During summer, phytoplankton biomass was highest in waters with salinity between about 5 and 23. In waters between 5 and 23, phytoplankton biomass was primarily (> 50%) composed of < 5 μm cells. The results from this study support the idea that a microbial food web characterizes mass and energy flow through the planktonic food web in Apalachicola Bay and other estuaries. During winter, the carbonxhlorophylla ratio averaged 56 ± 60 (standard deviation). During summer, the ratio ranged from 23 to 345, with highest values occurring in waters with salinity between about 8 and 22. The carbonxhlorophylla ratio was positively related to the percent of chlorophyll < 5 μm in size during summer.     

Spurts in India's population growth during the twentieth century: a spatial view

The years 1921 and 1951 have been unmarked, in the literature on the theme, as the critical divides in India's population growth since the beginning of the present century. The veracity of this observation has been tested for different parts of the country by analysing data for individual districts. While the above generalization did hold good at the all-India level, it was found true for only one-third of the districts at the disaggregated level. The relevance of the demographic transition model to India was also examined. The model did apply, in essence, to the Indian situation but its quantitative parameters as derived fropm the Western experience, were not appropriate.     

数字地质调查系统中空间数据库建库流程 关键技术的解决方案

空间数据库建库流程是数字地质调查系统总体技术流程的一个重要组成部分。针对地质人员实际工作量等方面的几个关键技术问题提出了详细的解决方案．并在数字地质调查系统的软件系统中以辅助建库工具、辅助检查工具、数据检索工具的形式加以实现。为建库提供了技术保障,保证了数据的质量,有效地提高了地质人员对地质调查系统的应用能力和建库的效率。