Climate change and transportation in Northern Canada: an integrated impact assessment

The physical and economic impacts of climate warming in the Mackenzie River Valley, Northwest Territories, Canada are estimated using a combination of stochastic modelling, econometric-modelling and input-output analysis. The attempt was to illustrate the utility of using analytical models for long-term impact assessment as well as to estimate the potential impacts from projected climate warming in the region. A scenario approach, based on three global circulation models, was used, with an emphasis on modelling climate variability, river ice conditions and economic impacts. The transportation system was used as a central focus linking the physical and socio-economic components. Despite the significant warming projected for the region, results show the economic impacts from changes in transportation to be relatively minor, with the greatest changes being in the tertiary, or service, sector.     

THE TRANSIENT ELECTROMAGNETIC RESPONSE OF A CONDUCTING SPHERE IN AN IMPERFECTLY CONDUCTING HALF-SPACE*

The presence of a conducting environment about a spherical ore body must be considered when calculating the transient electromagnetic response of the ore body due to a step current flowing in a large circular loop at the earth's surface. Failure to do this can easily lead to errors in excess of 10% in numerical calculations. Moreover, there is only a limited time interval in which the response of the spherical conductor is easily seen. In a poorly conducting ground the resonance response of the sphere is the first to be excited. Later, however, the non-resonance or wave-type response is excited. These waves destructively interfere and finally the response of the sphere decays with time as t^?7/2. For a range of times and depths the best loop for detecting the sphere has about the same radius as the sphere.     

西藏高原对其北方环流系统的影响

本文应用1956年6月到1957年5月一年内逐日亚欧500mb 天气图,计算历次高低压系统经过西藏高原以北时在强度和速度方面的改变,证明这些改变是有规则的,在地域上和季节上皆表现出独特性。     

北半球海平面气压场月偏距中心的研究

本文用统计方法研究1930—1939年期间逐月北半球气压偏距中心的活动规律.发现同一月份的气压偏距中心在北半球某些地区有集中出现的情况,这些集中地区如在阿拉斯加的南方、大西洋的东北部以及亚欧大陆的北冰洋沿岸.这些地区可以认为是北半球环流异常的关鍵性地区.绝大多数的偏距中心在逐月之间可以发现它们的联系.在过渡季节,大多数偏距中心自西向东移动.在偏距中心相互作用的基础上,本文还讨论了北半球某些地区的气候特点.     

A SURVEY OF HIGH RESOLUTION GEOMAGNETICS *

The development of optically pumped and monitored “atomic” magnetometers has allowed the application of greater resolution in geomagnetic measurements for exploration purposes. This paper presents a survey of instrumentation in use, the variety of exploration techniques that are being used in practice, and an estimate of their state of development. Alkali metals (rubidium and cesium) and helium have been used as active elements to obtain the magnetic-field dependent Larmor frequency. Each of these instruments is capable of obtaining high resolution data (data with sensitivity numerically smaller than one-tenth gamma). They have been adapted for airborne, land, and marine usage. Such sensitivity has enabled the rapid development of geomagnetic gradiometers, high sensitivity aeromagnetics, diurnally reduced ground surveys, broad-band magneto-telluric surveys, susceptibility measurements, and convenient magnetic search and location techniques. Outlines of each procedure and an example of its application are given.     

Pilot-scale field model tests for detecting landfill leachate intrusion into the subsurface using a grid-net electrical conductivity measurement system

The grid-net electrical conductivity measurement system for detecting exact locations of landfill leachate intrusion in the subsurface was developed in this study. Laboratory and pilot-scale field model tests were performed to evaluate the direct application of a grid-net electrical conductivity measurement system for the detection of landfill leachate. A significant increase in electrical conductivity of soil was observed by adding landfill leachate. This can be explained as an increase in electrical conductivity of pore fluid due to an increase in leachate constituents as charge carriers. In pilot-scale field model tests, leachate intrusion locations were accurately identified at the initial stage of landfill leachate release by the grid-net electrical conductivity measurement system. The electrical conductivity of the subsurface before leachate injection lay within a small range of 24.8–43.0 S/cm. The electrical conductivity values in detected points were approximately ten times more than the conductivity values of the subsurface without landfill leachate intrusion. The results in this study indicate that the grid-net electrical conductivity measurement method has a possible application for detecting locations of landfill leachate intrusion into the subsurface at the initial stage, and thus has great potential in monitoring leachate leakage at waste landfills.     

Walrus (Odobenus rosmarus) predation on adult thick-billed murres (Uria lomvia) at Coats Island, Nunavut, Canada

Although the diet of walrus ( Odobenus rosmarus ) is considered varied, records of walrus consuming marine birds are rare in the published literature. In 2001 and 2002 we observed walrus foraging on adult thick-billed murres ( Uria lomvia ) at Coats Island in Nunavut, Canada. Approximately 46% of the attacks on murres were successful, and as many as 67 murres may have been killed in one day in August 2002. All soft parts of the murres were sucked out, with carcasses of only bones, feathers and skin left floating on the water. The extent to which predation on seabirds by walrus occurs across the eastern Arctic is unknown, but it could represent an important source of mortality for murres at some breeding colonies.     

Evaluation of the seismic performance of a three‐story ordinary moment‐resisting concrete frame

This study focuses on the seismic performance of Ordinary Moment‐Resisting Concrete Frames (OMRCF) designed only for gravity loads. For this purpose, a 3‐story OMRCF was designed in compliance with the minimum design requirements in the American Concrete Institute Building Code ACI 318 (1999). This model frame was a regular structure with flexure‐dominated response. A 1/3‐scale 3‐story model was constructed and tested under quasi‐static reversed cyclic lateral loading. The overall behavior of the OMRCF was quite stable without abrupt strength degradation. The measured base shear strength was larger than the design base shear force for seismic zones 1, 2A and 2B calculated using UBC 1997. Moreover, this study used the capacity spectrum method to evaluate the seismic performance of the frame. The capacity curve was obtained from the experimental results for the specimen and the demand curve was established using the earthquake ground motions recorded at various stations with different soil conditions. Evaluation of the test results shows that the 3‐story OMRCF can resist design seismic loads of zones 1, 2A, 2B, 3 and 4 with soil types S_A and S_B . For soil type S_C , the specimen was satisfactory in seismic zones 1, 2A, 2B and 3. For soil type S_D , the OMRCF was only satisfactory for seismic zones 1 and 2A. Copyright © 2004 John Wiley & Sons, Ltd.     

LANDSLIDE POTENTIALITY OF THE TSENGWEN RESERVOIR WATERSHED, TAIWAN

To recognize the geographical characteristics of the landslide areas will be helpful for the watershedmanagement in the reservoir watershed. According to the quantitative analysis, we'll take differentscores and weighting for the potential parameters of the landslide areas in the Tsengwen reservoirwatershed, and in the meanwhile, we'll extract the different factors, including the slope, aspect,altitude, soil and geological textures etc., and the results shown as maximum one--day rainfall, ratio offorests and average relief is the most affecting parameters on the potential risk map of landslide areas.