Effect of soil temperature changes on geogrid strains

Abstract: Temperatures were measured along instrumented geogrids to determine thermal strains and their changes with seasonal temperatures. It was observed that the application of temperature correction to the measured strain values by electrical wire resistance (EWR) strain gauges to compensate for temperature-induced strains is not correct. Because of the effects of soil confinement, the geogrids confined with soil do not undergo thermal expansion or contraction from temperature change if slippage between the soil and geogrid cannot occur. Instead of thermal strains, thermal stress or thermal force will be developed in the geogrids with the magnitude depending on the elastic properties, temperature change, and linear coefficient of thermal expansion

Laboratory investigation on freeze separation of saline mine waste water

Abstract: The extraction and upgrading process for bitumen from oil sand deposits in Alberta, Canada currently requires large volumes of process water. This water demand is fulfilled by importing water and recycling/reuse of clarified process water. Reuse of the clarified water results in the steady increase of organic and inorganic (salt) contaminant concentrations in the recycle water. Using a specially designed flume housed in a cold room, trickle freeze separation was evaluated for contaminant separation of saline solutions used as a surrogate for mine waste water. Experiments were conducted at various ambient temperatures, salt concentrations and mass flow rates. Melting proved to be more effective at concentrating salts than freezing. The trickle freeze/thaw process developed during the experiment was very effective at separating and concentrating the salts into a smaller volume. For source waters frozen at an ambient temperature of -15 degrees C and with 3000 mg/L (NaCl) or less, 80% removal of salts was possible after melting 9% of the produced ice. For source waters with higher concentrations (20,000 mg/L), 80% removal was possible after melting 27% of the produced ice

Change Point Estimation in Monitoring Survival Time

Precise identification of the time when a change in a hospital outcome has occurred enables clinical experts to search for a potential special cause more effectively. In this paper, we develop change point estimation methods for survival time of a clinical procedure in the presence of patient mix in a Bayesian framework. We apply Bayesian hierarchical models to formulate the change point where there exists a step change in the mean survival time of patients who underwent cardiac surgery. The data are right censored since the monitoring is conducted over a limited follow-up period. We capture the effect of risk factors prior to the surgery using a Weibull accelerated failure time regression model. Markov Chain Monte Carlo is used to obtain posterior distributions of the change point parameters including location and magnitude of changes and also corresponding probabilistic intervals and inferences. The performance of the Bayesian estimator is investigated through simulations and the result shows that precise estimates can be obtained when they are used in conjunction with the risk-adjusted survival time CUSUM control charts for different magnitude scenarios. The proposed estimator shows a better performance where a longer follow-up period, censoring time, is applied. In comparison with the alternative built-in CUSUM estimator, more accurate and precise estimates are obtained by the Bayesian estimator. These superiorities are enhanced when probability quantification, flexibility and generalizability of the Bayesian change point detection model are also considered

Economic evaluation of three populational screening strategies for cervical cancer in the county of Valles Occidental: CRICERVA clinical trial

Copyright @ 2011 Acera et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.A high percentage of cervical cancer cases have not undergone cytological tests within 10 years prior to diagnosis. Different population interventions could improve coverage in the public system, although costs will also increase. The aim of this study was to compare the effectiveness and the costs of three types of population interventions to increase the number of female participants in the screening programmes for cancer of the cervix carried out by Primary Care in four basic health care areas.Fondo de Investigación Sanitaria del Instituto Carlos III de Madri

Proceedings of the Tailings and Mine Waste Conference 2009 (TMW 2009)

The Tailings and Mine Waste Conference provides mine waste managers, engineers, regulators and researchers an opportunity to discuss the latest developments in tailings and mine waste management, to present new ideas and to make professional contacts with others who have mutual interests and goals

Proceedings of the International Oil Sands Tailings Conference 2008 (IOSTC 2008)

Bringing together experts and interested individuals to address tailings technology and management in Alberta's Oil Sands Industry, the International Oil Sands Tailings Conference (IOSTC) offers the most recent developments in oil sands tailings and management to the international community through invited speakers and select technical presentations

Laboratory Properties of Mine Tailings

Abstract: A vast amount and variety of mine tailings are produced around the world each day. These mining wastes must be properly managed. To evaluate mine tailings disposal technology, the appropriate engineering properties of the tailings must be ascertained. The results of a laboratory investigation on the engineering properties of four different tailings are presented. First, some of the basic properties of the tailings are described. Large-strain consolidation tests and hydraulic conductivity tests are then described. The techniques for saturating and placing the tailings sample prior to carrying out the consolidation tests are given. Column drying and shrinkage tests for investigating the desiccation behavior of mine tailings are outlined. Furthermore, water retention characteristic tests using both the pressure-plate extractor and the saturated salt solution desiccator are outlined. Finally, shear strength parameter tests are described. The engineering properties derived from these tests are then presented and compared with the published results on similar types of tailings

Laboratory properties of mine tailings

A vast amount and variety of mine tailings are produced around the world each day. These mining wastes must be properly managed. To evaluate mine tailings disposal technology, the appropriate engineering properties of the tailings must be ascertained. The results of a laboratory investigation on the engineering properties of four different tailings are presented. First, some of the basic properties of the tailings are described. Large-strain consolidation tests and hydraulic conductivity tests are then described. The techniques for saturating and placing the tailings sample prior to carrying out the consolidation tests are given. Column drying and shrinkage tests for investigating the desiccation behavior of mine tailings are outlined. Furthermore, water retention characteristic tests using both the pressure-plate extractor and the saturated salt solution desiccator are outlined. Finally, shear strength parameter tests are described. The engineering properties derived from these tests are then presented and compared with the published results on similar types of tailings.Key words: mine tailings, engineering properties, consolidation, hydraulic conductivity, water retention curve, evaporation rate. </jats:p