An element formulation for perturbed motion about the center of mass

The perturbed motion of a rigid body about its center of mass, is formulated in terms of the six elements:l, the magnitude of the angular momentum vector;h, the total energy; and , two linear functions of the independent variable; and ₁ and ₁, two Euler angles that orientate the inertial frame with respect to the unperturbed solution. Solutions from the element formulation and the original Euler equations are numerically compared using shuttle-type data. For applied torques smaller than a given magnitude, the element formulation produced the following results: (1) larger step sizes in the numerical integration of the differential equations, resulting in an overall computational time-saving, and (2) more significant figures of accuracy in the computation of the variables describing the state of the rigid body.     

Evidence of Spatio-Temporal Variations in Contaminants Discharging to a Peri-Urban Stream

Xenobiotic organic compounds can be discharged from contaminated groundwater inflow and may seep into streams from multiple pathways with very different dynamics, some not fully understood. In this study, we investigated the spatio-temporal variation of chlorinated ethenes discharging from a former industrial site (with two main contaminant sources, A and B) into a stream system in a heterogeneous clay till setting in eastern Denmark. The investigated reach and near-stream surroundings are representative of peri-urban settings, with a mix of high channel alteration and more natural stream environment. We therefore propose an approach for risk assessing impacts arising from such complex contamination patterns, accounting for potential spatio-temporal fluctuations and presence of multiple pathways. Our study revealed substantial variations in pathway contributions and overall contaminant mass discharge to the stream. Variable contaminant contributions arising from both groundwater seepage and urban drains were identified in the channelized part of the north stream, primarily from source A. Furthermore, variations in the hyporheic and shallow groundwater flows were found to enhance contaminant transport from source B. These processes result in an increase of the overall mass of contaminant discharged, correlating with the channels' flow. Thus, an in-stream control plane approach was found to be an effective method for integrating multiple and variable discharge contributions quantitatively, although information on specific contaminant sources is lost. This study highlights the complexity and variability of contaminant fluxes occurring at the interface between groundwater and peri-urban streams, and calls for the consideration of these variations when designing monitoring programs and remedial actions for contaminated sites with the potential to impact streams.     

An evaluation of measures for quantifying map information

A real-time map must not contain too much information. Therefore, we need measures of map information that could be guidelines for the selection of data layers and the real-time generalisation process. In this paper we evaluate measures of the amount of information and the distribution of information. The evaluation is performed by (1) defining measures, (2) implementing the measures, (3) computing the measures for some test maps, and finally (4) comparing the values of the measures with human judgement of the map information. For amount of information, we found that the measures number of objects, number of points and object line length had better correspondence with human judgement than object area. We also found that measures based on the size of Voronoi regions of objects (respectively points) can be used for identifying the distribution of information. The results are based on the testing of only building objects. Future work should extend the test, using all object types.     

Geographic clustering of firms and urban form: a multivariate analysis

This paper provides an empirical framework that applies spatial statistics methods to assess the relation between the change in the geographical clustering of firms and the emergence of urban form. We contend that where firms locate and eventually cluster give rise to the way commercial and industrial land uses are organized over space, which in turn defines the shape of urban form. Accordingly, the objectives of our work are twofold: (1) to identify the extent and shape of firm clustering and co-location at the intra-metropolitan level, and (2) examine how the change in the geographic clustering of different industries contributes to decentralization and the evolution of urban form. Spatial statistics methods and tools were vital and helped to fulfill these objectives.      

Business establishment mobility behavior in urban areas: a microanalytical model for the City of Hamilton in Ontario,Canada

We present a microanalytical firm mobility model for the City of Hamilton, Canada, developed with data from the Statistics Canada Business Register. Contributing to the scarce literature on firm migration behavior, we explore and model the determinants of mobility among small and medium size firms who retained less than 200 employees between 1996 and 1997. Our exploratory results suggest that short distance moves are more common and tend to occur among smaller firms. Econometric modeling results support these assertions and indicate that the willingness to move can be explained by a firm’s internal characteristics (e.g. age, size, growth and industry type) as well as location factors related to the urban environment where the firm is located. The modeling results will serve as input for the development of an agent-based firmographic decision support system that can be used to inform the planning process in the study area.      

Luminescence Variations in Fast-Growing Stalagmites from Uppsala, Sweden

Two fast‐growing stalagmites from a cellar vault in Uppsala, southeast Sweden, are analysed for their luminescent properties. The results indicate that variations in luminescence intensity in the stalagmites are annual. Due to problems in finding a suitable absolute dating method this assumption cannot yet be firmly tested; however, results from radiocarbon dating of one of the stalagmites do not contradict the proposal that the laminae are annual. If so, the speleothems have been growing for 10–15 years with a growth rate of 3–8 mm per year, which is a similar rate to other fast‐growing speleothems in Great Britain that have formed from the reaction of lime mortar and carbon dioxide. It is likely that the assumed annual laminae of the luminescence record represent a flush of organic material.     

Using Astrophysical Data Archives In Astrophysical Research: RXTEAs A Case Study

In this paper, we highlight the significance of astrophysical dataarchives, and the great opprtunities they are offering for researchersin general, and those in the developing countries in particular. Wefocus on high energy astrophysical data archives, taking RXTE as a casestudy, where we give a brief introduction to this satellite and itsinstrumentation. Then we explain in certain detail the processes ofsearch and retrieval of RXTE's archival data, finally touching verybriefly upon its data analysis.     

Assessment of carbon in woody plants and soil across a vineyard-woodland landscape

Background

Quantification of ecosystem services, such as carbon (C) storage, can demonstrate the benefits of managing for both production and habitat conservation in agricultural landscapes. In this study, we evaluated C stocks and woody plant diversity across vineyard blocks and adjoining woodland ecosystems (wildlands) for an organic vineyard in northern California. Carbon was measured in soil from 44 one m deep pits, and in aboveground woody biomass from 93 vegetation plots. These data were combined with physical landscape variables to model C stocks using a geographic information system and multivariate linear regression.

Results

Field data showed wildlands to be heterogeneous in both C stocks and woody tree diversity, reflecting the mosaic of several different vegetation types, and storing on average 36.8 Mg C/ha in aboveground woody biomass and 89.3 Mg C/ha in soil. Not surprisingly, vineyard blocks showed less variation in above- and belowground C, with an average of 3.0 and 84.1 Mg C/ha, respectively.

Conclusions

This research demonstrates that vineyards managed with practices that conserve some fraction of adjoining wildlands yield benefits for increasing overall C stocks and species and habitat diversity in integrated agricultural landscapes. For such complex landscapes, high resolution spatial modeling is challenging and requires accurate characterization of the landscape by vegetation type, physical structure, sufficient sampling, and allometric equations that relate tree species to each landscape. Geographic information systems and remote sensing techniques are useful for integrating the above variables into an analysis platform to estimate C stocks in these working landscapes, thereby helping land managers qualify for greenhouse gas mitigation credits. Carbon policy in California, however, shows a lack of focus on C stocks compared to emissions, and on agriculture compared to other sectors. Correcting these policy shortcomings could create incentives for ecosystem service provision, including C storage, as well as encourage better farm stewardship and habitat conservation.

     

Passive earth pressure on embedded vertical plate anchors in sand

Passive earth pressure on embedded anchor plates constitutes a viable resisting force for the design of underground structures. In the current practice, these forces are empirically calculated, ignoring the effects of the depth of embedment and the level of consolidation of the surrounding soil, which takes place during plate installation on the in situ stress levels. Accordingly, wide discrepancies between predicted and measured pullout capacities of these plates were reported in the literature. Numerical model was developed using finite-element technique and the constitutive law of Mohr?CCoulomb to simulate the case of a retaining wall partially supported by an embedded anchor plate in sand. The results produced in this investigation showed that the passive earth pressure acting on anchor plates increases due to the increase of angle of shearing resistance and the overconsolidation ratio of sand, and it decreases due to an increase of the embedment depth of anchor. Design theories were developed for the case of embedded anchor plate in overconsolidated sand. The theories developed will satisfy the design needed in terms of allowable pullout load and/or displacement.     

On the nature of rapidly deepening Canadian East Coast winter storms

Abstract

During the Canadian Atlantic Storms Program (CASP) field project from 15 January to 15 March 1986, seven storms underwent rapid deepening either within or adjacent to the observational network. The most rapid deepening phase of these storms was associated with the surface low‐pressure centre being located close to to the rain‐snow boundary and the end of this phase was associated with the low centre eventually moving to sub‐freezing surface temperatures. Precipitation bands of both rain and snow occurred during maximum deepening. Observations are consistent with divergence and subsidence occurring near the centre itself. It is suggested that a mesoscale circulation initiated by melting snow significantly affects the deepening process.