1,267 research outputs found

    Model and Reinforcement Learning for Markov Games with Risk Preferences

    Full text link
    We motivate and propose a new model for non-cooperative Markov game which considers the interactions of risk-aware players. This model characterizes the time-consistent dynamic "risk" from both stochastic state transitions (inherent to the game) and randomized mixed strategies (due to all other players). An appropriate risk-aware equilibrium concept is proposed and the existence of such equilibria is demonstrated in stationary strategies by an application of Kakutani's fixed point theorem. We further propose a simulation-based Q-learning type algorithm for risk-aware equilibrium computation. This algorithm works with a special form of minimax risk measures which can naturally be written as saddle-point stochastic optimization problems, and covers many widely investigated risk measures. Finally, the almost sure convergence of this simulation-based algorithm to an equilibrium is demonstrated under some mild conditions. Our numerical experiments on a two player queuing game validate the properties of our model and algorithm, and demonstrate their worth and applicability in real life competitive decision-making.Comment: 38 pages, 6 tables, 5 figure

    Effects of grain size distribution on the initial strain shear modulus of calcareous sand

    Get PDF
    The soil’s small strain shear modulus, Gmax or G0, is applied in dynamic behavior analyses and is correlated to other soil properties (density and void ratio) for predicting soil dynamic behavior under seismic loadings such as earthquakes, machinery or traffic vibrations. However, for calcareous sands, selecting representative samples for the field conditions is difficult; therefore, almost all measured soil parameters (post-seismic properties) do not reflect exactly the soil state before seismic loading. In some cases of dynamic loading, a change in grain size distribution (GSD) of soils, especially for calcareous sands might occur. Moreover, many of these sand types behave differently from silica sands owing to their mineralogy, particle characterization, soil skeleton, and the continuous changing of particle size. For this reason, a series of isotropic consolidation tests in ranges of confining pressure from 25 to 300 kPa as well as bender element measurements on a calcareous sand and on a reference silica sand were performed in this study. The effects of differences in gradation and in the type of material on the soil’s small strain shear modulus, Gmax, are discussed

    Soil Transport Implement

    Get PDF
    The design of the Soil Transport Implement (STI) for SKITTER is presented. The purpose of STI is to provide a protective layer of lunar soil for the lunar modules. The objective is to cover the lunar module with a layer of soil approximately two meters thick within a two week period. The amount of soil required to cover the module is roughly 77 dump truck loads or three million earth pounds. A spinning disk is employed to accomplish its task. STI is an autonomous, teleoperated system. The design incorporates the latest advances in composite materials and high strength, light weight alloys to achieve a high strength to weight ratio. The preliminary design should only be used to assess the feasibility of employing a spinning wheel as a soil transport implement. A mathematical model of the spinning wheel was used to evaluate the performance of this design

    Measuring unmet need for contraception among women in rural areas of Papua New Guinea

    Get PDF
    Located in the South West Pacific region, with a population of 7.5 million, Papua New Guinea (PNG) is among a group of Pacific countries with sub-optimal health status. The maternal mortality ratio is 171 per 100,000 live births. Unmet need for contraception and family planning services, although poorly understood in PNG, may be one of the underlying causes of poor maternal health. This study set out to measure the prevalence and trends in unmet need for contraception and the identified socioeconomic factors associated with contraceptive use among women of reproductive age (15–49 years) in PNG. Data available from the Integrated Health and Demographic Surveillance System (IHDSS) were used in this study. A sub-population data set was extracted of 1434 women who gave birth in the preceding two years and resided in four rural surveillance sites: Asaro, Hides, Hiri and Karkar. Analyzes of unmet need for contraception were performed with respect to birth spacing and limiting the number of births. Unmet need for contraception was 34% for the previous birth, 37% for the current pregnancy, and 49% for future family planning. The total unmet need for contraception was 35%, of which 49% was for spacing births and 51% for limiting births. Women's age, education and household wealth are the most significant determinants of unmet need for contraception. The high level of unmet need for contraception may contribute to women's poor health status in PNG. Urgent programming responses from the health sector for supporting effective interventions to increase availability and use of contraceptives are required. Analyzes of unmet need for contraception were performed with respect to birth spacing and limiting the number of births. Unmet need for contraception was 34% for the previous birth, 37% for the current pregnancy, and 49% for future family planning. The total unmet need for contraception was 35%, of which 49% was for spacing births and 51% for limiting births. Women's age, education and household wealth are the most significant determinants of unmet need for contraception. The high level of unmet need for contraception may contribute to women's poor health status in PNG. Urgent programming responses from the health sector for supporting effective interventions to increase availability and use of contraceptives are required. Analyzes of unmet need for contraception were performed with respect to birth spacing and limiting the number of births. Unmet need for contraception was 34% for the previous birth, 37% for the current pregnancy, and 49% for future family planning. The total unmet need for contraception was 35%, of which 49% was for spacing births and 51% for limiting births. Women's age, education and household wealth are the most significant determinants of unmet need for contraception. The high level of unmet need for contraception may contribute to women's poor health status in PNG. Urgent programming responses from the health sector for supporting effective interventions to increase availability and use of contraceptives are required. 37% for the current pregnancy, and 49% for future family planning. The total unmet need for contraception was 35%, of which 49% was for spacing births and 51% for limiting births. Women's age, education and household wealth are the most significant determinants of unmet need for contraception. The high level of unmet need for contraception may contribute to women's poor health status in PNG. Urgent programming responses from the health sector for supporting effective interventions to increase availability and use of contraceptives are required. 37% for the current pregnancy, and 49% for future family planning. The total unmet need for contraception was 35%, of which 49% was for spacing births and 51% for limiting births. Women's age, education and household wealth are the most significant determinants of unmet need for contraception. The high level of unmet need for contraception may contribute to women's poor health status in PNG. Urgent programming responses from the health sector for supporting effective interventions to increase availability and use of contraceptives are required. The high level of unmet need for contraception may contribute to women's poor health status in PNG. Urgent programming responses from the health sector for supporting effective interventions to increase availability and use of contraceptives are required. The high level of unmet need for contraception may contribute to women's poor health status in PNG. Urgent programming responses from the health sector for supporting effective interventions to increase availability and use of contraceptives are required

    2018 Fine Art Graduation Exhibition Catalogue

    Get PDF
    MIXTAPE Fanshawe Fine Art Class of 2018 Graduation Exhibition The Arts ProjectApril 4-14Opening Reception - Saturday April 7th, 20187pm-10pm Guest Speaker: Cora Cluetthttps://first.fanshawec.ca/famd_design_fineart_gradcatalogues/1012/thumbnail.jp

    Thermal certification tests of Orbiter Thermal Protection System tiles coated with KSC coating slurries

    Get PDF
    Thermal tests of Orbiter thermal protection system (TPS) tiles, which were coated with borosilicate glass slurries fabricated at Kennedy Space Center (KSC), were performed in the Radiant Heat Test Facility and the Atmospheric Reentry Materials & Structures Evaluation Facility at Johnson Space Center to verify tile coating integrity after exposure to multiple entry simulation cycles in both radiant and convective heating environments. Eight high temperature reusable surface insulation (HRSI) tiles and six low temperature reusable surface insulation (LRSI) tiles were subjected to 25 cycles of radiant heat at peaked surface temperatures of 2300 F and 1200 F, respectively. For the LRSI tiles, an additional cycle at peaked surface temperature of 2100 F was performed. There was no coating crack on any of the HRSI specimens. However, there were eight small coating cracks (less than 2 inches long) on two of the six LRSI tiles on the 26th cycle. There was practically no change on the surface reflectivity, physical dimensions, or weight of any of the test specimens. There was no observable thermal-chemical degradation of the coating either. For the convective heat test, eight HRSI tiles were tested for five cycles at a surface temperature of 2300 F. There was no thermal-induced coating crack on any of the test specimens, almost no change on the surface reflectivity, and no observable thermal-chemical degradation with an exception of minor slumping of the coating under painted TPS identification numbers. The tests demonstrated that KSC's TPS slurries and coating processes meet the Orbiter's thermal specification requirements

    Blood Lead Levels and Risk Factors for Lead Exposure in a Pediatric Population in Ho Chi Minh City, Vietnam.

    Get PDF
    Although lead recycling activities are a known risk factor for elevated blood levels in South East Asia, little is known regarding the prevalence of and risk factors for elevated blood lead levels (BLL) among the general pediatric population in Vietnam. This study is a cross-sectional evaluation of 311 children from Children's Hospital #2 in Ho Chi Minh City, Vietnam. Capillary blood lead testing was performed using the LeadCare II. Mean BLLs were 4.97 ÎĽg/dL (Standard Deviation (SD) 5.50), with 7% of the participants having levels greater than 10 ÎĽg/dL. Living in Bing Duong province (OR 2.7, 95% CI 1.4-5.6.1) or the Dong Nai province (OR 2.3, 95% CI 1.0-5.1) and having an age greater than 12 months (OR 6.0, 95% CI 3.1-11.8) were associated with higher BLLs. The prevalence of elevated BLLs in Vietnam is consistent with other SE Asian countries. Mean BLLs in Ho Chi Minh City are markedly less than those seen in a separate study of children living near lead recycling activities. Additional evaluation is necessary to better detail potential risk factors if screening is to be implemented within Vietnam
    • …
    corecore