Science.gov

Sample records for demand elasticities

  1. A Note on Comparing the Elasticities of Demand Curves.

    ERIC Educational Resources Information Center

    Nieswiadomy, Michael

    1986-01-01

    Demonstrates a simple and useful way to compare the elasticity of demand at each price (or quantity) for different demand curves. The technique is particularly useful for the intermediate microeconomic course. (Author)

  2. Consumer brand choice: individual and group analyses of demand elasticity.

    PubMed

    Oliveira-Castro, Jorge M; Foxall, Gordon R; Schrezenmaier, Teresa C

    2006-03-01

    Following the behavior-analytic tradition of analyzing individual behavior, the present research investigated demand elasticity of individual consumers purchasing supermarket products, and compared individual and group analyses of elasticity. Panel data from 80 UK consumers purchasing 9 product categories (i.e., baked beans, biscuits, breakfast cereals, butter, cheese, fruit juice, instant coffee, margarine and tea) during a 16-week period were used. Elasticity coefficients were calculated for individual consumers with data from all or only 1 product category (intra-consumer elasticities), and for each product category using all data points from all consumers (overall product elasticity) or 1 average data point per consumer (interconsumer elasticity). In addition to this, split-sample elasticity coefficients were obtained for each individual with data from all product categories purchased during weeks 1 to 8 and 9 to 16. The results suggest that: 1) demand elasticity coefficients calculated for individual consumers purchasing supermarket food products are compatible with predictions from economic theory and behavioral economics; 2) overall product elasticities, typically employed in marketing and econometric research, include effects of interconsumer and intraconsumer elasticities; 3) when comparing demand elasticities of different product categories, group and individual analyses yield similar trends; and 4) individual differences in demand elasticity are relatively consistent across time, but do not seem to be consistent across products. These results demonstrate the theoretical, methodological, and managerial relevance of investigating the behavior of individual consumers.

  3. Consumer Brand Choice: Individual and Group Analyses of Demand Elasticity

    PubMed Central

    Oliveira-Castro, Jorge M; Foxall, Gordon R; Schrezenmaier, Teresa C

    2006-01-01

    Following the behavior-analytic tradition of analyzing individual behavior, the present research investigated demand elasticity of individual consumers purchasing supermarket products, and compared individual and group analyses of elasticity. Panel data from 80 UK consumers purchasing 9 product categories (i.e., baked beans, biscuits, breakfast cereals, butter, cheese, fruit juice, instant coffee, margarine and tea) during a 16-week period were used. Elasticity coefficients were calculated for individual consumers with data from all or only 1 product category (intra-consumer elasticities), and for each product category using all data points from all consumers (overall product elasticity) or 1 average data point per consumer (interconsumer elasticity). In addition to this, split-sample elasticity coefficients were obtained for each individual with data from all product categories purchased during weeks 1 to 8 and 9 to 16. The results suggest that: 1) demand elasticity coefficients calculated for individual consumers purchasing supermarket food products are compatible with predictions from economic theory and behavioral economics; 2) overall product elasticities, typically employed in marketing and econometric research, include effects of interconsumer and intraconsumer elasticities; 3) when comparing demand elasticities of different product categories, group and individual analyses yield similar trends; and 4) individual differences in demand elasticity are relatively consistent across time, but do not seem to be consistent across products. These results demonstrate the theoretical, methodological, and managerial relevance of investigating the behavior of individual consumers. PMID:16673823

  4. Price elasticity of demand: An overlooked concept

    SciTech Connect

    1995-10-01

    An all-too-common mistake in analyzing the uranium market is to assume that demand for uranium is driven only by the design and operational parameters of nuclear power plants. Because it is generally accepted that demand for uranium is inelastic, not much attention has been given to how prices can indirectly affect demand. The purpose of this paper is to highlight the factors that are most sensitive to uranium prices, and to show how they alter uranium demand.

  5. Consumer Brand Choice: Individual and Group Analyses of Demand Elasticity

    ERIC Educational Resources Information Center

    Oliveira-Castro, Jorge M.; Foxall, Gordon R.; Schrezenmaier, Teresa C.

    2006-01-01

    Following the behavior-analytic tradition of analyzing individual behavior, the present research investigated demand elasticity of individual consumers purchasing supermarket products, and compared individual and group analyses of elasticity. Panel data from 80 UK consumers purchasing 9 product categories (i.e., baked beans, biscuits, breakfast…

  6. The Arc Elasticity of Demand: A Note and Comment.

    ERIC Educational Resources Information Center

    Vaughan, Michael B.

    1988-01-01

    Examines the suitability of the traditional arc elasticity measure as a component of the economics curriculum. Demonstrates that the midpoint measure is subject to shortcomings as it invariably approaches one when price changes become large. Discusses point elasticity of demand as an alternative to the midpoint measure in the principles course.…

  7. Estimating elasticity for residential electricity demand in China.

    PubMed

    Shi, G; Zheng, X; Song, F

    2012-01-01

    Residential demand for electricity is estimated for China using a unique household level dataset. Household electricity demand is specified as a function of local electricity price, household income, and a number of social-economic variables at household level. We find that the residential demand for electricity responds rather sensitively to its own price in China, which implies that there is significant potential to use the price instrument to conserve electricity consumption. Electricity elasticities across different heterogeneous household groups (e.g., rich versus poor and rural versus urban) are also estimated. The results show that the high income group is more price elastic than the low income group, while rural families are more price elastic than urban families. These results have important policy implications for designing an increasing block tariff.

  8. The Cross-Elasticity of Demand for National Newspaper Advertising.

    ERIC Educational Resources Information Center

    Busterna, John C.

    1987-01-01

    Measures the extent to which other media compete with newspapers in the market for national advertising, using coefficients of the cross-elasticity of demand between newspapers and eight other media. Concluded that no other media reside in the same product market for national advertising. (MM)

  9. Teaching Price, Income, and Cross Elasticity of Demand: Another Approach.

    ERIC Educational Resources Information Center

    Zahka, William J.

    One of the most important, yet difficult concepts to teach in an undergraduate course in intermediate microeconomics is the all-embracing concept of elasticity of demand. This paper details a four part teaching approach developed to make this most important aspect of microeconomic theory more understandable. Part 1 develops the approach for…

  10. ROLE OF ESTROGEN RECEPTOR-α ON FOOD DEMAND ELASTICITY

    PubMed Central

    Minervini, Vanessa; Rowland, Neil E.; Robertson, Kimberly L.; Foster, Thomas C.

    2016-01-01

    Estrogens have been shown to have an inhibitory effect on food intake under free-feeding conditions, yet the effects of estrogens on food-maintained operant responding have been studied to a much lesser extent and, thus, are not well understood. Therefore, the purpose of the present experiment was to use a behavioral economics paradigm to assess differences in demand elasticity between mice with knockout of the estrogen receptor subtype α, knockout of subtype β, and their wild type controls. The mice responded in a closed economy, and the price of food was increased by increasing the fixed-ratio response requirement every four sessions. Overall, we found that mice with the knockout of receptor subtype α had the most elastic demand functions. Therefore, under these conditions, estrogens increased food seeking via activation of the receptor subtype α. The results were inconsistent with those reported by previous studies that employed free-feeding conditions. PMID:25869426

  11. Role of estrogen receptor-α on food demand elasticity.

    PubMed

    Minervini, Vanessa; Rowland, Neil E; Robertson, Kimberly L; Foster, Thomas C

    2015-05-01

    Estrogens have been shown to have an inhibitory effect on food intake under free-feeding conditions, yet the effects of estrogens on food-maintained operant responding have been studied to a much lesser extent and, thus, are not well understood. Therefore, the purpose of the present experiment was to use a behavioral economics paradigm to assess differences in demand elasticity between mice with knockout of the estrogen receptor subtype α, knockout of subtype β, and their wild type controls. The mice responded in a closed economy, and the price of food was increased by increasing the fixed-ratio response requirement every four sessions. Overall, we found that mice with the knockout of receptor subtype α had the most elastic demand functions. Therefore, under these conditions, estrogens increased food seeking via activation of the receptor subtype α. The results were inconsistent with those reported by previous studies that employed free-feeding conditions.

  12. Relationship between the Uncompensated Price Elasticity and the Income Elasticity of Demand under Conditions of Additive Preferences.

    PubMed

    Sabatelli, Lorenzo

    2016-01-01

    Income and price elasticity of demand quantify the responsiveness of markets to changes in income and in prices, respectively. Under the assumptions of utility maximization and preference independence (additive preferences), mathematical relationships between income elasticity values and the uncompensated own and cross price elasticity of demand are here derived using the differential approach to demand analysis. Key parameters are: the elasticity of the marginal utility of income, and the average budget share. The proposed method can be used to forecast the direct and indirect impact of price changes and of financial instruments of policy using available estimates of the income elasticity of demand.

  13. Relationship between the Uncompensated Price Elasticity and the Income Elasticity of Demand under Conditions of Additive Preferences

    PubMed Central

    Sabatelli, Lorenzo

    2016-01-01

    Income and price elasticity of demand quantify the responsiveness of markets to changes in income and in prices, respectively. Under the assumptions of utility maximization and preference independence (additive preferences), mathematical relationships between income elasticity values and the uncompensated own and cross price elasticity of demand are here derived using the differential approach to demand analysis. Key parameters are: the elasticity of the marginal utility of income, and the average budget share. The proposed method can be used to forecast the direct and indirect impact of price changes and of financial instruments of policy using available estimates of the income elasticity of demand. PMID:26999511

  14. Synthesizing Econometric Evidence: The Case of Demand Elasticity Estimates.

    PubMed

    DeCicca, Philip; Kenkel, Don

    2015-06-01

    Econometric estimates of the responsiveness of health-related consumer demand to higher prices are often key ingredients for risk policy analysis. We review the potential advantages and challenges of synthesizing econometric evidence on the price-responsiveness of consumer demand. We draw on examples of research on consumer demand for health-related goods, especially cigarettes. We argue that the overarching goal of research synthesis in this context is to provide policy-relevant evidence for broad-brush conclusions. We propose three main criteria to select among research synthesis methods. We discuss how in principle and in current practice synthesis of research on the price-elasticity of smoking meets our proposed criteria. Our analysis of current practice also contributes to academic research on the specific policy question of the effectiveness of higher cigarette prices to reduce smoking. Although we point out challenges and limitations, we believe more work on research synthesis in this area will be productive and important.

  15. Price elasticities of alcohol demand: evidence from Russia.

    PubMed

    Goryakin, Yevgeniy; Roberts, Bayard; McKee, Martin

    2015-03-01

    In this paper, we estimate price elasticities of demand of several types of alcoholic drinks, using 14 rounds of data from the Russia Longitudinal Monitoring Survey-HSE, collected from 1994 until 2009. We deal with potential confounding problems by taking advantage of a large number of control variables, as well as by estimating community fixed effect models. All in all, although alcohol prices do appear to influence consumption behaviour in Russia, in most cases the size of effect is modest. The finding that two particularly problematic drinks-cheap vodka and fortified wine-are substitute goods also suggests that increasing their prices may not lead to smaller alcohol consumption. Therefore, any alcohol pricing policies in Russia must be supplemented with other measures, such as restrictions on numbers of sales outlets or their opening times.

  16. Price Elasticities of Food Demand: Compensated vs Uncompensated.

    PubMed

    Clements, Kenneth W; Si, Jiawei

    2016-11-01

    Two recent studies have provided a comprehensive review/summary of a large number of estimates of the price elasticity of food consumption using a meta-regression approach. In this letter, we introduce a way of removing the income effect from these elasticities to recover the compensated elasticities. Although the income effect is small, the compensated elasticities vary by income group. Both types of elasticity should possibly be considered when assessing the impact of policy changes on food consumption. Copyright © 2015 John Wiley & Sons, Ltd.

  17. Optimal Electricity Charge Strategy Based on Price Elasticity of Demand for Users

    NASA Astrophysics Data System (ADS)

    Li, Xin; Xu, Daidai; Zang, Chuanzhi

    The price elasticity is very important for the prediction of electricity demand. This paper mainly establishes the price elasticity coefficient for electricity in single period and inter-temporal. Then, a charging strategy is established based on these coefficients. To evaluate the strategy proposed, simulations of the two elastic coefficients are carried out based on the history data of a certain region.

  18. Examining the short-run price elasticity of gasoline demand in the United States

    NASA Astrophysics Data System (ADS)

    Brannan, Michael James

    Estimating the consumer demand response to changes in the price of gasoline has important implications regarding fuel tax policies and environmental concerns. There are reasons to believe that the short-run price elasticity of gasoline demand fluctuates due to changing structural and behavioral factors. In this paper I estimate the short-run price elasticity of gasoline demand in two time periods, from 2001 to 2006 and from 2007 to 2010. This study utilizes data at both the national and state levels to produce estimates. The short-run price elasticities range from -0.034 to -0.047 during 2001 to 2006, compared to -0.058 to -0.077 in the 2007 to 2010 period. This paper also examines whether there are regional differences in the short-run price elasticity of gasoline demand in the United States. However, there appears to only be modest variation in price elasticity values across regions.

  19. 39 CFR 3050.26 - Documentation of demand elasticities and volume forecasts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Postal Service shall provide econometric estimates of demand elasticity for all postal products accompanied by the underlying econometric models and the input data sets used; and a volume forecast for...

  20. Using the Price Elasticity of Demand in Educational Decision Making.

    ERIC Educational Resources Information Center

    Smith, Joseph D.; Moracco, Judy N.

    1984-01-01

    Describes a study and methods used by Navy Campus to choose a funding arrangement that would make the best use of the money available for voluntary educational purposes. Discusses modifying the economic concept of price elasticity to the interests of educationally oriented audiences. (JOW)

  1. The price elasticity of demand for heroin: matched longitudinal and experimental evidence#

    PubMed Central

    Olmstead, Todd A.; Alessi, Sheila M.; Kline, Brendan; Pacula, Rosalie Liccardo; Petry, Nancy M.

    2015-01-01

    This paper reports estimates of the price elasticity of demand for heroin based on a newly constructed dataset. The dataset has two matched components concerning the same sample of regular heroin users: longitudinal information about real-world heroin demand (actual price and actual quantity at daily intervals for each heroin user in the sample) and experimental information about laboratory heroin demand (elicited by presenting the same heroin users with scenarios in a laboratory setting). Two empirical strategies are used to estimate the price elasticity of demand for heroin. The first strategy exploits the idiosyncratic variation in the price experienced by a heroin user over time that occurs in markets for illegal drugs. The second strategy exploits the experimentally-induced variation in price experienced by a heroin user across experimental scenarios. Both empirical strategies result in the estimate that the conditional price elasticity of demand for heroin is approximately −0.80. PMID:25702687

  2. An Airline-Based Multilevel Analysis of Airfare Elasticity for Passenger Demand

    NASA Technical Reports Server (NTRS)

    Castelli, Lorenzo; Ukovich, Walter; Pesenti, Raffaele

    2003-01-01

    Price elasticity of passenger demand for a specific airline is estimated. The main drivers affecting passenger demand for air transportation are identified. First, an Ordinary Least Squares regression analysis is performed. Then, a multilevel analysis-based methodology to investigate the pattern of variation of price elasticity of demand among the various routes of the airline under study is proposed. The experienced daily passenger demands on each fare-class are grouped for each considered route. 9 routes were studied for the months of February and May in years from 1999 to 2002, and two fare-classes were defined (business and economy). The analysis has revealed that the airfare elasticity of passenger demand significantly varies among the different routes of the airline.

  3. The price elasticity of demand for heroin: Matched longitudinal and experimental evidence.

    PubMed

    Olmstead, Todd A; Alessi, Sheila M; Kline, Brendan; Pacula, Rosalie Liccardo; Petry, Nancy M

    2015-05-01

    This paper reports estimates of the price elasticity of demand for heroin based on a newly constructed dataset. The dataset has two matched components concerning the same sample of regular heroin users: longitudinal information about real-world heroin demand (actual price and actual quantity at daily intervals for each heroin user in the sample) and experimental information about laboratory heroin demand (elicited by presenting the same heroin users with scenarios in a laboratory setting). Two empirical strategies are used to estimate the price elasticity of demand for heroin. The first strategy exploits the idiosyncratic variation in the price experienced by a heroin user over time that occurs in markets for illegal drugs. The second strategy exploits the experimentally induced variation in price experienced by a heroin user across experimental scenarios. Both empirical strategies result in the estimate that the conditional price elasticity of demand for heroin is approximately -0.80.

  4. Dose and elasticity of demand for self-administered cocaine in rats.

    PubMed

    Kearns, David N; Silberberg, Alan

    2016-04-01

    The present experiment tested whether the elasticity of demand for self-administered cocaine in rats is dose-dependent. Subjects lever pressed for three different doses of intravenous cocaine - 0.11, 0.33, and 1.0 mg/kg/infusion - on a demand procedure where the number of lever presses required per infusion increased within a session. The main finding was that demand for the 0.11 mg/kg dose was more elastic than it was for the two larger doses. There was no difference in demand elasticity between the 0.33 and 1.0 mg/kg doses. These results parallel findings previously reported in monkeys. The present study also demonstrated that a within-session procedure can be used to generate reliable demand curves.

  5. Decomposition of the price and income elasticities of the consumer demand for gasoline

    SciTech Connect

    Archibald, R.; Gillingham, R.

    1981-04-01

    The authors specify and estimate a model of the short-run demand for gasoline which allows them to decompose a consumer's gasoline demand elasticities into miles-driven and driving-efficiency components. Their model is estimated using detailed household survey data which allows direct focus on the short run, holding both the household's automobile stock and demographic profile fixed. Among the most interesting results are: (1) The data allow interesting insights to be drawn into the interrelationship between these important variables and household behavior with respect to gasoline consumption, miles driven, and driving efficiency. (2) The gasoline demand behavior of one-car and multi-car households differ significantly from each other. Evaluated at overall sample means, one-car households have higher (in absolute value) price elasticites for gasoline, miles driven and fuel-efficiency demand. Conversely, multi-car households have higher (in absolute value) total expenditure elasticities for each category. (3) For both one-car and multi-car households, roughly 75% of the estimated price elasticity and roughly 80% of the estimated total-expenditure elasticity of gasoline demand stem from the miles-driven component. The estimated fuel-efficiency elasticities, though smaller than their standard errors, indicate that households respond to changes in prices and total-expenditure levels not only by changing the number of miles they drive, but also by changing the efficiency with which they drive them. 23 references, 3 tables.

  6. Differences in price elasticities of demand for health insurance: a systematic review.

    PubMed

    Pendzialek, Jonas B; Simic, Dusan; Stock, Stephanie

    2016-01-01

    Many health insurance systems apply managed competition principles to control costs and quality of health care. Besides other factors, managed competition relies on a sufficient price-elastic demand. This paper presents a systematic review of empirical studies on price elasticity of demand for health insurance. The objective was to identify the differing international ranges of price elasticity and to find socio-economic as well as setting-oriented factors that influence price elasticity. Relevant literature for the topic was identified through a two-step identification process including a systematic search in appropriate databases and further searches within the references of the results. A total of 45 studies from countries such as the USA, Germany, the Netherlands, and Switzerland were found. Clear differences in price elasticity by countries were identified. While empirical studies showed a range between -0.2 and -1.0 for optional primary health insurance in the US, higher price elasticities between -0.6 and -4.2 for Germany and around -2 for Switzerland were calculated for mandatory primary health insurance. Dutch studies found price elasticities below -0.5. In consideration of all relevant studies, age and poorer health status were identified to decrease price elasticity. Other socio-economic factors had an unclear impact or too limited evidence. Premium level, range of premiums, homogeneity of benefits/coverage and degree of forced decision were found to have a major influence on price elasticity in their settings. Further influence was found from supplementary insurance and premium-dependent employer contribution.

  7. Price Elasticity of Demand: An A-Level Economics Revision Exercise.

    ERIC Educational Resources Information Center

    Williams, Paul

    1992-01-01

    Presents a review exercise requiring students to sort diagrams and descriptions of price elasticity of demand. Reports that students are given jumbled diagrams and explanations that they must arrange in proper form. Reveals that some items are designed as distractors. (SG)

  8. Economic analysis of the water demand in the hotels and restaurants sector: Shadow prices and elasticities

    NASA Astrophysics Data System (ADS)

    Angulo, Ana; Atwi, Majed; Barberán, Ramón; Mur, Jesús

    2014-08-01

    Despite the growing economic importance of tourism, and its impact on relative water shortage, little is known about the role that water plays in the productive process of hotels and restaurants and, therefore, the possible implications of water demand management policy for this sector. This study aims to fill this gap. It is based on the microdata of 676 firms in the sector, operating in the city of Zaragoza (Spain) for a 12 year period. Based on the Translog cost function, we estimate the shadow price of water in the short run and, from a long-run perspective, its direct price elasticity, its cross elasticities relative to labor, capital, and supplies, and its elasticity with respect to the level of output. The results obtained show that water provides sector firms returns that are on average higher than its price, although in the case of hotels the margin is really narrow. This situation provides policy makers with a margin for applying price increases without affecting the sector's viability, with some caution in the case of hotels. Water demand elasticity equals -0.38 in the case of hotels, but it is not significant in the case of restaurants and bar-cafes; hence, only in hotels is there potential for influencing water use patterns, encouraging the resource's conservation through pricing policy. Moreover, capital is a substitutive factor of water, and the elasticity of water with respect to output is 0.40, all of which should also be considered by policy makers in water resource management.

  9. Price elasticity of demand for malt liquor beer: findings from a US pilot study.

    PubMed

    French, Michael Thomas; Browntaylor, Didra; Bluthenthal, Ricky Neville

    2006-05-01

    Our objective is to estimate the relative price elasticity of demand for malt liquor beer (MLB), regular beer, hard liquor, and a combined group of all other alcoholic beverages. Three hundred and twenty-nine alcohol consumers (mostly male) in South-Central Los Angeles answered a series of questions pertaining to expected consumption responses to hypothetical price increases. We found that based on a 10% price increase, the mean price elasticity of demand (% change in quantity demanded / % change in price) was -0.79 for MLB drinkers, -1.14 for regular beer drinkers, -1.11 for hard liquor drinkers, and -1.69 for the combined group of all other drinkers. Logistic regression analysis revealed that the personal characteristics significantly related to being a MLB drinker were older age, not working, being homeless, and a daily drinker. Daily (or nearly daily) drinkers were more likely to be married, earning lower incomes, and hard liquor drinkers. This study is the first to investigate the price elasticity of demand for MLB drinkers and other heavy alcohol consumers in poor urban neighborhoods of the US. Future research can use the methods from this pilot study to more rigorously examine and compare the price sensitivity among heavy drinking groups.

  10. Price and income elasticities of energy demand: Some estimates for Kuwait using two econometric models

    SciTech Connect

    Al-Mutairi, N.H.; Eltony, M.N.

    1995-12-31

    This paper estimates the demand for energy in Kuwait for the period 1965-1989 using two econometric models: a cointegration and error correction model (ECM) and a simultaneous-equation model (SEM). The results obtained from both models are similar. It is found that the energy demand is inelastic with respect to price in the short and long run, and while it is elastic in the long run, the energy demand is inelastic with respect to income in the short run. Both models` validation shows that the ECM performed better in replicating the past than the simultaneous model, suggesting the need to use the ECM to identify future prospects for energy demand in Kuwait.

  11. What U.S. data should be used to measure the price elasticity of demand for alcohol?

    PubMed

    Ruhm, Christopher J; Jones, Alison Snow; McGeary, Kerry Anne; Kerr, William C; Terza, Joseph V; Greenfield, Thomas K; Pandian, Ravi S

    2012-12-01

    This paper examines how estimates of the price elasticity of demand for beer vary with the choice of alcohol price series examined. Our most important finding is that the commonly used ACCRA price data are unlikely to reliably indicate alcohol demand elasticities-estimates obtained from this source vary drastically and unpredictably. As an alternative, researchers often use beer taxes to proxy for alcohol prices. While the estimated beer taxes elasticities are more stable, there are several problems with using taxes, including difficulties in accounting for cross-price effects. We believe that the most useful estimates reported in this paper are obtained using annual Uniform Product Code (UPC) "barcode" scanner data on grocery store alcohol prices. These estimates suggest relatively low demand elasticity, probably around -0.3, with evidence that the elasticities are considerably overstated in models that control for beer but not wine or spirits prices.

  12. China's medical savings accounts: an analysis of the price elasticity of demand for health care.

    PubMed

    Yu, Hao

    2016-09-20

    Although medical savings accounts (MSAs) have drawn intensive attention across the world for their potential in cost control, there is limited evidence of their impact on the demand for health care. This paper is intended to fill that gap. First, we built up a dynamic model of a consumer's problem of utility maximization in the presence of a nonlinear price schedule embedded in an MSA. Second, the model was implemented using data from a 2-year MSA pilot program in China. The estimated price elasticity under MSAs was between -0.42 and -0.58, i.e., higher than that reported in the literature. The relatively high price elasticity suggests that MSAs as an insurance feature may help control costs. However, the long-term effect of MSAs on health costs is subject to further analysis.

  13. Predictors of the nicotine reinforcement threshold, compensation, and elasticity of demand in a rodent model of nicotine reduction policy*

    PubMed Central

    Grebenstein, Patricia E.; Burroughs, Danielle; Roiko, Samuel A.; Pentel, Paul R.; LeSage, Mark G.

    2015-01-01

    Background The FDA is considering reducing the nicotine content in tobacco products as a population-based strategy to reduce tobacco addiction. Research is needed to determine the threshold level of nicotine needed to maintain smoking and the extent of compensatory smoking that could occur during nicotine reduction. Sources of variability in these measures across sub-populations also need to be identified so that policies can take into account the risks and benefits of nicotine reduction in vulnerable populations. Methods The present study examined these issues in a rodent nicotine self- administration model of nicotine reduction policy to characterize individual differences in nicotine reinforcement thresholds, degree of compensation, and elasticity of demand during progressive reduction of the unit nicotine dose. The ability of individual differences in baseline nicotine intake and nicotine pharmacokinetics to predict responses to dose reduction was also examined. Results Considerable variability in the reinforcement threshold, compensation, and elasticity of demand was evident. High baseline nicotine intake was not correlated with the reinforcement threshold, but predicted less compensation and less elastic demand. Higher nicotine clearance predicted low reinforcement thresholds, greater compensation, and less elastic demand. Less elastic demand also predicted lower reinforcement thresholds. Conclusions These findings suggest that baseline nicotine intake, nicotine clearance, and the essential value of nicotine (i.e. elasticity of demand) moderate the effects of progressive nicotine reduction in rats and warrant further study in humans. They also suggest that smokers with fast nicotine metabolism may be more vulnerable to the risks of nicotine reduction. PMID:25891231

  14. An Analysis of the Price Elasticity of Demand for Household Appliances

    SciTech Connect

    Fujita, Kimberly; Dale, Larry; Fujita, K. Sydny

    2008-01-25

    This report summarizes our study of the price elasticity of demand for home appliances, including refrigerators, clothes washers, and dishwashers. In the context of increasingly stringent appliance standards, we are interested in what kind of impact the increased manufacturing costs caused by higher efficiency requirements will have on appliance sales. We begin with a review of existing economics literature describing the impact of economic variables on the sale of durable goods.We then describe the market for home appliances and changes in this market over the past 20 years, performing regression analysis on the shipments of home appliances and relevant economic variables including changes to operating cost and household income. Based on our analysis, we conclude that the demand for home appliances is price inelastic.

  15. A static predictor of seismic demand on frames based on a post-elastic deflected shape

    USGS Publications Warehouse

    Mori, Y.; Yamanaka, T.; Luco, N.; Cornell, C.A.

    2006-01-01

    Predictors of seismic structural demands (such as inter-storey drift angles) that are less time-consuming than nonlinear dynamic analysis have proven useful for structural performance assessment and for design. Luco and Cornell previously proposed a simple predictor that extends the idea of modal superposition (of the first two modes) with the square-root-of-sum-of-squares (SRSS) rule by taking a first-mode inelastic spectral displacement into account. This predictor achieved a significant improvement over simply using the response of an elastic oscillator; however, it cannot capture well large displacements caused by local yielding. A possible improvement of Luco's predictor is discussed in this paper, where it is proposed to consider three enhancements: (i) a post-elastic first-mode shape approximated by the deflected shape from a nonlinear static pushover analysis (NSPA) at the step corresponding to the maximum drift of an equivalent inelastic single-degree-of-freedom (SDOF) system, (ii) a trilinear backbone curve for the SDOF system, and (iii) the elastic third-mode response for long-period buildings. Numerical examples demonstrate that the proposed predictor is less biased and results in less dispersion than Luco's original predictor. Copyright ?? 2006 John Wiley & Sons, Ltd.

  16. What U.S. Data Should be Used to Measure the Price Elasticity of Demand for Alcohol?*

    PubMed Central

    Ruhm, Christopher J.; Jones, Alison Snow; McGeary, Kerry Anne; Kerr, William C.; Terza, Joseph V.; Greenfield, Thomas K.; Pandian, Ravi S.

    2012-01-01

    This paper examines how estimates of the price elasticity of demand for beer vary with the choice of alcohol price series examined. Our most important finding is that the commonly used ACCRA price data are unlikely to reliably indicate alcohol demand elasticities—estimates obtained from this source vary drastically and unpredictably. As an alternative, researchers often use beer taxes to proxy for alcohol prices. While the estimated beer taxes elasticities are more stable, there are several problems with using taxes, including difficulties in accounting for cross-price effects. We believe that the most useful estimates reported in this paper are obtained using annual Uniform Product Code (UPC) “barcode” scanner data on grocery store alcohol prices. These estimates suggest relatively low demand elasticity, probably around −0.3, with evidence that the elasticities are considerably overstated in models that control for beer but not wine or spirits prices. PMID:23022631

  17. Estimating the own-price elasticity of demand for irrigation water in the Musi catchment of India

    NASA Astrophysics Data System (ADS)

    Davidson, Brian; Hellegers, Petra

    2011-10-01

    SummaryAs irrigation water is an input into a production process, its demand must be 'derived'. According to theory, a derived demand schedule should be downward sloping and dependent on the outputs produced from it, the prices of other inputs and the price of the water itself. Problems arise when an attempt is made to estimate the demand for irrigation water and the resulting own-price elasticity of demand, as the uses to which water is put are spatially, temporarily and geographically diverse. Because water is not generally freely traded, what normally passes for an estimate of the own-price elasticity of demand for irrigation water is usually a well argued assumption or an estimate that is derived from a simulation model of a hypothesized producer. Such approaches tend to provide an inadequate explanation of what is an extremely complex and important relationship. An adequate explanation of the relationship between the price and the quantity demanded of water should be one that not only accords with the theoretical expectations, but also accounts for the diversity of products produced from water (which includes the management practices of farmers), the seasons in which it is used and over the region within which it is used. The objective in this article is to present a method of estimating the demand curve for irrigation water. The method uses actual field data which is collated using the Residual Method to determine the value of the marginal product of water deployed over a wide range of crops, seasons and regions. These values of the marginal products, all which must lie of the input demand schedule for water, are then ordered from the highest value to the lowest. Then, the amount of irrigation water used for each product, in each season and in each region is cumulatively summed over the range of uses according to the order of the values of the marginal products. This data, once ordered, is then used to econometrically estimate the demand schedule from which

  18. Understanding heterogeneity in price elasticities in the demand for alcohol for older individuals.

    PubMed

    Ayyagari, Padmaja; Deb, Partha; Fletcher, Jason; Gallo, William; Sindelar, Jody L

    2013-01-01

    This paper estimates the price elasticity of demand for alcohol using Health and Retirement Study data. To account for unobserved heterogeneity in price responsiveness, we use finite mixture models. We recover two latent groups, one is significantly responsive to price, but the other is unresponsive. The group with greater responsiveness is disadvantaged in multiple domains, including health, financial resources, education and perhaps even planning abilities. These results have policy implications. The unresponsive group drinks more heavily, suggesting that a higher tax would fail to curb the negative alcohol-related externalities. In contrast, the more disadvantaged group is more responsive to price, thus suffering greater deadweight loss, yet this group consumes fewer drinks per day and might be less likely to impose negative externalities.

  19. Price elasticity of the demand for sugar sweetened beverages and soft drinks in Mexico.

    PubMed

    Colchero, M A; Salgado, J C; Unar-Munguía, M; Hernández-Ávila, M; Rivera-Dommarco, J A

    2015-12-01

    A large and growing body of scientific evidence demonstrates that sugar drinks are harmful to health. Intake of sugar-sweetened beverages (SSB) is a risk factor for obesity and type 2 diabetes. Mexico has one of the largest per capita consumption of soft drinks worldwide and high rates of obesity and diabetes. Fiscal approaches such as taxation have been recommended as a public health policy to reduce SSB consumption. We estimated an almost ideal demand system with linear approximation for beverages and high-energy food by simultaneous equations and derived the own and cross price elasticities for soft drinks and for all SSB (soft drinks, fruit juices, fruit drinks, flavored water and energy drinks). Models were stratified by income quintile and marginality index at the municipality level. Price elasticity for soft drinks was -1.06 and -1.16 for SSB, i.e., a 10% price increase was associated with a decrease in quantity consumed of soft drinks by 10.6% and 11.6% for SSB. A price increase in soft drinks is associated with larger quantity consumed of water, milk, snacks and sugar and a decrease in the consumption of other SSB, candies and traditional snacks. The same was found for SSB except that an increase in price of SSB was associated with a decrease in snacks. Higher elasticities were found among households living in rural areas (for soft drinks), in more marginalized areas and with lower income. Implementation of a tax to soft drinks or to SSB could decrease consumption particularly among the poor. Substitutions and complementarities with other food and beverages should be evaluated to assess the potential impact on total calories consumed.

  20. Monetary Policy Rules, Supply Shocks, and the Price-Level Elasticity of Aggregate Demand: A Graphical Examination.

    ERIC Educational Resources Information Center

    Kyer, Ben L.; Maggs, Gary E.

    1995-01-01

    Utilizes two-dimensional price and output graphs to demonstrate the way that the price-level elasticity of aggregate demand affects alternative monetary policy rules designed to cope with random aggregate supply shocks. Includes graphs illustrating price-level, real Gross Domestic Product (GDP), nominal GDP, and nominal money supply targeting.…

  1. The impact of food prices on consumption: a systematic review of research on the price elasticity of demand for food.

    PubMed

    Andreyeva, Tatiana; Long, Michael W; Brownell, Kelly D

    2010-02-01

    In light of proposals to improve diets by shifting food prices, it is important to understand how price changes affect demand for various foods. We reviewed 160 studies on the price elasticity of demand for major food categories to assess mean elasticities by food category and variations in estimates by study design. Price elasticities for foods and nonalcoholic beverages ranged from 0.27 to 0.81 (absolute values), with food away from home, soft drinks, juice, and meats being most responsive to price changes (0.7-0.8). As an example, a 10% increase in soft drink prices should reduce consumption by 8% to 10%. Studies estimating price effects on substitutions from unhealthy to healthy food and price responsiveness among at-risk populations are particularly needed.

  2. Explaining the variation in elasticity estimates of gasoline demand in the United States: A meta-analysis

    SciTech Connect

    Espey, M.

    1996-12-01

    Many econometric studies of gasoline demand have been conducted over the years when fuel prices where high and concerns about energy conservation and security of supply were prominent. Studies were motivated by interest in gasoline consumers` sensitivity to fuel price changes, for the insight this might give in explaining cross country differences in gas consumption and driving and in predicting the impact of fuel tax changes on driving, fuel consumption and government revenue collections. The author used meta-analysis to determine if there are factors that systematically affect price and income elasticity estimates in studies of gasoline demand in the United States.

  3. Elasticity of Demand for Tuition Fees at an Institution of Higher Education

    ERIC Educational Resources Information Center

    Langelett, George; Chang, Kuo-Liang; Ola' Akinfenwa, Samson; Jorgensen, Nicholas; Bhattarai, Kopila

    2015-01-01

    Using a conjoint survey of 161 students at South Dakota State University (SDSU), we mapped a probability-of-enrolment curve for SDSU students, consistent with demand theory. A quasi-demand curve was created from the conditional-logit model. This study shows that along with the price of tuition fees, distance from home, availability of majors, and…

  4. Regional Differences in the Price-Elasticity of Demand for Energy

    SciTech Connect

    Bernstein, M. A.; Griffin, J.

    2006-02-01

    At the request of the National Renewable Energy Laboratory (NREL), the RAND Corporation examined the relationship between energy demand and energy prices with the focus on whether the relationships between demand and price differ if these are examined at different levels of data resolution. In this case, RAND compares national, regional, state, and electric utility levels of data resolution. This study is intended as a first step in helping NREL understand the impact that spatial disaggregation of data can have on estimating the impacts of their programs. This report should be useful to analysts in NREL and other national laboratories, as well as to policy nationals at the national level. It may help them understand the complex relationships between demand and price and how these might vary across different locations in the United States.

  5. Estimating the Market Demand and Elasticity for Enrollment at an Institution

    ERIC Educational Resources Information Center

    Wohlgemuth, Darin

    2013-01-01

    This article presents an applied research framework that can be helpful in tuition and net price policy discussions. It is the classic microeconomic concept of market demand applied to enrollment management in higher education. The policy relevance includes measuring a response to price. For example, the results of this model will allow the…

  6. The Effects of Price Discrimination on the Elasticity of Demand for Higher Education.

    ERIC Educational Resources Information Center

    Weinberg, Ira

    The purpose of this study was to determine what effect price discrimination (differential pricing) would have on institutional gross-fee income. Enrollment and tuition data were gathered from all schools in one particular market area for the years 1969-72. In this situation it was determined that overall demand for higher education was highly…

  7. Dynamic on-demand defragmentation in flexible bandwidth elastic optical networks.

    PubMed

    Yin, Yawei; Wen, Ke; Geisler, David J; Liu, Ruiting; Yoo, S J B

    2012-01-16

    While flexible bandwidth elastic optical networking is a promising direction for future networks, the spectral fragmentation problem in such a network inevitably raises the blocking probability and significantly degrades network performance. This paper addresses the spectral defragmentation problem using an auxiliary graph based approach, which transforms the problem into a matter of finding the maximum independent set (MIS) in the constructed auxiliary graph. The enabling technologies and defragmentation-capable node architectures, together with heuristic defragmentation algorithms are proposed and evaluated. Simulation results show that the proposed min-cost defragmentation algorithms can significantly reduce the blocking probability of incoming requests in a spectrally fragmented flexible bandwidth optical network, while substantially minimizing the number of disrupted connections.

  8. Demand assessment and price-elasticity estimation of quality-improved primary health care in Palestine: a contribution from the contingent valuation method.

    PubMed

    Mataria, Awad; Luchini, Stéphane; Daoud, Yousef; Moatti, Jean-Paul

    2007-10-01

    This paper proposes a new methodology to assess demand and price-elasticity for health care, based on patients' stated willingness to pay (WTP) values for certain aspects of health care quality improvements. A conceptual analysis of how respondents consider contingent valuation (CV) questions allowed us to specify a probability density function of stated WTP values, and consequently, to model a demand function for quality-improved health care, using a parametric survival approach. The model was empirically estimated using a CV study intended to assess patients' values for improving the quality of primary health care (PHC) services in Palestine. A random sample of 499 individuals was interviewed following medical consultation in four PHC centers. Quality was assessed using a multi-attribute approach; and respondents valued seven specific quality improvements using a decomposed valuation scenario and a payment card elicitation technique. Our results suggest an inelastic demand at low user fees levels, and when the price-increase is accompanied with substantial quality-improvements. Nevertheless, demand becomes more and more elastic if user fees continue to rise. On the other hand, patients' reactions to price-increase turn out to depend on their level of income. Our results can be used to design successful health care financing strategies that include a consideration of patients' preferences and financial capacities.

  9. Estimation of own and cross price elasticities of alcohol demand in the UK—A pseudo-panel approach using the Living Costs and Food Survey 2001–2009☆

    PubMed Central

    Meng, Yang; Brennan, Alan; Purshouse, Robin; Hill-McManus, Daniel; Angus, Colin; Holmes, John; Meier, Petra Sylvia

    2014-01-01

    The estimation of price elasticities of alcohol demand is valuable for the appraisal of price-based policy interventions such as minimum unit pricing and taxation. This study applies a pseudo-panel approach to the cross-sectional Living Cost and Food Survey 2001/2–2009 to estimate the own- and cross-price elasticities of off- and on-trade beer, cider, wine, spirits and ready-to-drinks in the UK. A pseudo-panel with 72 subgroups defined by birth year, gender and socioeconomic status is constructed. Estimated own-price elasticities from the base case fixed effect models are all negative and mostly statically significant (p < 0.05). Off-trade cider and beer are most elastic (−1.27 and −0.98) and off-trade spirits and on-trade ready-to-drinks are least elastic (−0.08 and −0.19). Estimated cross-price elasticities are smaller in magnitude with a mix of positive and negative signs. The results appear plausible and robust and could be used for appraising the estimated impact of price-based interventions in the UK. PMID:24508846

  10. Estimation of own and cross price elasticities of alcohol demand in the UK--A pseudo-panel approach using the Living Costs and Food Survey 2001-2009.

    PubMed

    Meng, Yang; Brennan, Alan; Purshouse, Robin; Hill-McManus, Daniel; Angus, Colin; Holmes, John; Meier, Petra Sylvia

    2014-03-01

    The estimation of price elasticities of alcohol demand is valuable for the appraisal of price-based policy interventions such as minimum unit pricing and taxation. This study applies a pseudo-panel approach to the cross-sectional Living Cost and Food Survey 2001/2-2009 to estimate the own- and cross-price elasticities of off- and on-trade beer, cider, wine, spirits and ready-to-drinks in the UK. A pseudo-panel with 72 subgroups defined by birth year, gender and socioeconomic status is constructed. Estimated own-price elasticities from the base case fixed effect models are all negative and mostly statically significant (p<0.05). Off-trade cider and beer are most elastic (-1.27 and -0.98) and off-trade spirits and on-trade ready-to-drinks are least elastic (-0.08 and -0.19). Estimated cross-price elasticities are smaller in magnitude with a mix of positive and negative signs. The results appear plausible and robust and could be used for appraising the estimated impact of price-based interventions in the UK.

  11. Textbook Factor Demand Curves.

    ERIC Educational Resources Information Center

    Davis, Joe C.

    1994-01-01

    Maintains that teachers and textbook graphics follow the same basic pattern in illustrating changes in demand curves when product prices increase. Asserts that the use of computer graphics will enable teachers to be more precise in their graphic presentation of price elasticity. (CFR)

  12. Gasoline demand in developing Asian countries

    SciTech Connect

    McRae, R.

    1994-12-31

    This paper presents econometric estimates of motor gasoline demand in eleven developing countries of Asia. The price and GDP per capita elasticities are estimated for each country separately, and for several pooled combinations of the countries. The estimated elasticities for the Asian countries are compared with those of the OECD countries. Generally, one finds that the OECD countries have GDP elasticities that are smaller, and price elasticities that are larger (in absolute value). The price elasticities for the low-income Asian countries are more inelastic than for the middle-income Asian countries, and the GDP elasticities are generally more elastic. 13 refs., 6 tabs.

  13. Using Empirical Point Elasticities To Teach Tax Incidence.

    ERIC Educational Resources Information Center

    Swinton, John R.; Thomas, Christopher R.

    2001-01-01

    Advocates use of point elasticities rather than arc elasticities or slopes of demand and supply curves to teach students about the economic impacts of excise taxes. Uses several available estimates of point elasticities of demand and supply of sugar to calculate the economic impacts of a penny-per-pound tax on sugar. (RLH)

  14. A Reevaluation of Price Elasticities for Irrigation Water

    NASA Astrophysics Data System (ADS)

    Howitt, Richard E.; Watson, William D.; Adams, Richard M.

    1980-08-01

    The effectiveness of pricing systems in the allocation of irrigation water is linked with the price elasticity of demand of farmers for water. Using microeconomic theory, it is shown that omission of the elasticity of demand for the crop produced leads to an inelastic bias in the demand for irrigated water. Linear programing approaches omit the product elasticity of demand and are consequently biased, whereas quadratic programing approaches to estimating derived demands for irrigation water include product demand functions. The difference between the resulting estimates are empirically demonstrated for regional derived demand functions estimated from a model of California's agricultural industry.

  15. Robust Unit Commitment Considering Uncertain Demand Response

    DOE PAGES

    Liu, Guodong; Tomsovic, Kevin

    2014-09-28

    Although price responsive demand response has been widely accepted as playing an important role in the reliable and economic operation of power system, the real response from demand side can be highly uncertain due to limited understanding of consumers' response to pricing signals. To model the behavior of consumers, the price elasticity of demand has been explored and utilized in both research and real practice. However, the price elasticity of demand is not precisely known and may vary greatly with operating conditions and types of customers. To accommodate the uncertainty of demand response, alternative unit commitment methods robust to themore » uncertainty of the demand response require investigation. In this paper, a robust unit commitment model to minimize the generalized social cost is proposed for the optimal unit commitment decision taking into account uncertainty of the price elasticity of demand. By optimizing the worst case under proper robust level, the unit commitment solution of the proposed model is robust against all possible realizations of the modeled uncertain demand response. Numerical simulations on the IEEE Reliability Test System show the e ectiveness of the method. Finally, compared to unit commitment with deterministic price elasticity of demand, the proposed robust model can reduce the average Locational Marginal Prices (LMPs) as well as the price volatility.« less

  16. Robust Unit Commitment Considering Uncertain Demand Response

    SciTech Connect

    Liu, Guodong; Tomsovic, Kevin

    2014-09-28

    Although price responsive demand response has been widely accepted as playing an important role in the reliable and economic operation of power system, the real response from demand side can be highly uncertain due to limited understanding of consumers' response to pricing signals. To model the behavior of consumers, the price elasticity of demand has been explored and utilized in both research and real practice. However, the price elasticity of demand is not precisely known and may vary greatly with operating conditions and types of customers. To accommodate the uncertainty of demand response, alternative unit commitment methods robust to the uncertainty of the demand response require investigation. In this paper, a robust unit commitment model to minimize the generalized social cost is proposed for the optimal unit commitment decision taking into account uncertainty of the price elasticity of demand. By optimizing the worst case under proper robust level, the unit commitment solution of the proposed model is robust against all possible realizations of the modeled uncertain demand response. Numerical simulations on the IEEE Reliability Test System show the e ectiveness of the method. Finally, compared to unit commitment with deterministic price elasticity of demand, the proposed robust model can reduce the average Locational Marginal Prices (LMPs) as well as the price volatility.

  17. Impact of improved building thermal efficiency on residential energy demand

    SciTech Connect

    Adams, R.C.; Rockwood, A.D.

    1983-04-01

    The impact of improved building shell thermal efficiency on residential energy demand is explored in a theoretical framework. The important economic literature on estimating the price elasticity of residential energy demand is reviewed. The specification of the residential energy demand model is presented. The data used are described. The empirical estimation of the residential energy demand model is described. (MHR)

  18. The Demand for Higher Education: Pennsylvania's Nonresident Tuition Experience.

    ERIC Educational Resources Information Center

    Noorbakhsh, Abbas; Culp, David

    2002-01-01

    Explores the estimation of tuition elasticity of resident and nonresident demand for higher education in the Pennsylvania State System of Higher Education. Finds that nonresident demand is price elastic, thus explaining the 40 percent decline in nonresident enrollment between 1991 and 1996 after average nonresident tuition increased nearly 20…

  19. The Demand for Higher Education Facing an Individual Institution

    ERIC Educational Resources Information Center

    Ghali, Moheb; And Others

    1977-01-01

    A model is used to analyze the choices made by a sample of high school graduates in Hawaii and estimates of the price elasticity and the cross-price elasticities of demand for enrollment at the University of Hawaii are obtained. Findings show that the demand is quite inelastic and that changes in tuition will not affect enrollment appreciably.…

  20. Demanding Satisfaction

    ERIC Educational Resources Information Center

    Oguntoyinbo, Lekan

    2010-01-01

    It was the kind of crisis most universities dread. In November 2006, a group of minority student leaders at Indiana University-Purdue University Indianapolis (IUPUI) threatened to sue the university if administrators did not heed demands that included providing more funding for multicultural student groups. This article discusses how this threat…

  1. Two Propositions on the Application of Point Elasticities to Finite Price Changes.

    ERIC Educational Resources Information Center

    Daskin, Alan J.

    1992-01-01

    Considers counterintuitive propositions about using point elasticities to estimate quantity changes in response to price changes. Suggests that elasticity increases with price along a linear demand curve, but falling quantity demand offsets it. Argues that point elasticity with finite percentage change in price only approximates percentage change…

  2. On the demand for prescription drugs: heterogeneity in price responses.

    PubMed

    Skipper, Niels

    2013-07-01

    This paper estimates the price elasticity of demand for prescription drugs using an exogenous shift in consumer co-payment caused by a reform in the Danish subsidy scheme for the general public. Using purchasing records for the entire Danish population, I show that the average price response for the most commonly used drug yields demand elasticities in the range of -0.36 to -0.5. The reform is shown to affect women, the elderly, and immigrants the most. Furthermore, this paper shows significant heterogeneity in the price response over different types of antibiotics, suggesting that the price elasticity of demand varies considerably even across relatively similar drugs.

  3. Can price get the monkey off our back? A meta-analysis of illicit drug demand.

    PubMed

    Gallet, Craig A

    2014-01-01

    Because of the increased availability of price data over the past 15 years, several studies have estimated the demand for illicit drugs, providing 462 estimates of the price elasticity. Results from estimating several meta-regressions reveal that these price elasticity estimates are influenced by a number of study characteristics. For instance, the price elasticity differs across drugs, with its absolute value being smallest for marijuana, compared with cocaine and heroin. Furthermore, price elasticity estimates are sensitive to whether demand is modeled in the short-run or the long-run, measures of quantity and price, whether or not alcohol and other illicit drugs are included in the specification of demand, and the location of demand. However, a number of other factors, including the functional form of demand, several specification issues, the type of data and method used to estimate demand, and the quality of the publication outlet, have less influence on the price elasticity.

  4. Estimating Demand for Alternatives to Cigarettes With Online Purchase Tasks

    PubMed Central

    O’Connor, Richard J.; June, Kristie M.; Bansal-Travers, Maansi; Rousu, Matthew C.; Thrasher, James F.; Hyland, Andrew; Cummings, K. Michael

    2013-01-01

    Objectives This study explored how advertising affects demand for cigarettes and potential substitutes, including snus, dissolvable tobacco, and medicinal nicotine. Methods A web-based experiment randomized 1062 smokers to see advertisements for alternative nicotine products or soft drinks, then complete a series of purchase tasks, which were used to estimate demand elasticity, peak consumption, and cross-price elasticity (CPE) for tobacco products. Results Lower demand elasticity and greater peak consumption were seen for cigarettes compared to all alternative products (p < .05). CPE did not differ across the alternative products (p ≤ .03). Seeing relevant advertisements was not significantly related to demand. Conclusions These findings suggest significantly lower demand for alternative nicotine sources among smokers than previously revealed. PMID:24034685

  5. Advertising media and cigarette demand.

    PubMed

    Goel, Rajeev K

    2011-01-01

    Using state-level panel data for the USA spanning three decades, this research estimates the demand for cigarettes. The main contribution lies in studying the effects of cigarette advertising disaggregated across five qualitatively different groups. Results show cigarette demand to be near unit elastic, the income effects to be generally insignificant and border price effects and habit effects to be significant. Regarding advertising effects, aggregate cigarette advertising has a negative effect on smoking. Important differences across advertising media emerge when cigarette advertising is disaggregated. The effects of public entertainment and Internet cigarette advertising are stronger than those of other media. Anti-smoking messages accompanying print cigarette advertising seem relatively more effective. Implications for smoking control policy are discussed.

  6. Modeling water demand when households have multiple sources of water

    NASA Astrophysics Data System (ADS)

    Coulibaly, Lassina; Jakus, Paul M.; Keith, John E.

    2014-07-01

    A significant portion of the world's population lives in areas where public water delivery systems are unreliable and/or deliver poor quality water. In response, people have developed important alternatives to publicly supplied water. To date, most water demand research has been based on single-equation models for a single source of water, with very few studies that have examined water demand from two sources of water (where all nonpublic system water sources have been aggregated into a single demand). This modeling approach leads to two outcomes. First, the demand models do not capture the full range of alternatives, so the true economic relationship among the alternatives is obscured. Second, and more seriously, economic theory predicts that demand for a good becomes more price-elastic as the number of close substitutes increases. If researchers artificially limit the number of alternatives studied to something less than the true number, the price elasticity estimate may be biased downward. This paper examines water demand in a region with near universal access to piped water, but where system reliability and quality is such that many alternative sources of water exist. In extending the demand analysis to four sources of water, we are able to (i) demonstrate why households choose the water sources they do, (ii) provide a richer description of the demand relationships among sources, and (iii) calculate own-price elasticity estimates that are more elastic than those generally found in the literature.

  7. Excise Taxes and the Price Elasticity of Demand.

    ERIC Educational Resources Information Center

    Gamble, Ralph C., Jr.

    1989-01-01

    Points out that, although the analysis of the imposition of an excise tax is widely used in economics courses, the consequences of a change in the tax rate are different and ignored. This article presents an effective way to teach about such a change. (GG)

  8. Estimating Demand Elasticities for Mobile Telecommunications in Austria

    DTIC Science & Technology

    2004-12-01

    Telecommunications Pol- icy, 27, 457-476. RTR, 2004, Informationen fiber den Telekom- Markt in Osterreich, Vienna, http://www.rtr. at/web .nsf/deutsch...Foreign Direct Investment, Production, and Welfare, No. 11 (June 2003). "* Dewenter, Ralf, The Economics of Media Markets, No. 10 (June 2003). "* Josten...Briduninger, Michael, A Note on Health Insurance and Growth, No. 6 (June 2003). * Dewenter, Ralf, Media Markets with Habit Formation, No. 5 (June

  9. Western municipal water conservation policy: The case of disaggregated demand

    NASA Astrophysics Data System (ADS)

    Burness, Stuart; Chermak, Janie; Krause, Kate

    2005-03-01

    We investigate aspects of the felicity of both incentive-based and command and control policies in effecting municipal water conservation goals. When demand can be disaggregated according to uses or users, our results suggest that policy efforts be focused on the submarket wherein demand is more elastic. Under plausible consumer parameters, a household production function approach to water utilization prescribes the nature of demand elasticities in alternative uses and squares nicely with empirical results from the literature. An empirical example illustrates. Overall, given data and other informational limitations, extant institutional structures, and in situ technology, our analysis suggests a predisposition for command and control policies over incentive-based tools.

  10. Non-urban mobile radio market demand forecast

    NASA Technical Reports Server (NTRS)

    Castruccio, P. A.; Cooper, J.

    1982-01-01

    A national nonmetropolitan land mobile traffic model for 1990-2000 addresses user classes, density classes, traffic mix statistics, distance distribution, geographic distribution, price elasticity, and service quality elasticity. Traffic demands for business, special industrial, and police were determined on the basis of surveys in 73 randomly selected nonurban counties. The selected services represent 69% of total demand. The results were extrapolated to all services in the non-SMSA areas of the contiguous United States. Radiotelephone services were considered separately. Total non-SMSA mobile radio demand (one way) estimates are given. General functional requirements include: hand portability, privacy, reduction of blind spots, two way data transmission, position location, slow scan imagery.

  11. Elastically Decoupling Dark Matter.

    PubMed

    Kuflik, Eric; Perelstein, Maxim; Lorier, Nicolas Rey-Le; Tsai, Yu-Dai

    2016-06-03

    We present a novel dark matter candidate, an elastically decoupling relic, which is a cold thermal relic whose present abundance is determined by the cross section of its elastic scattering on standard model particles. The dark matter candidate is predicted to have a mass ranging from a few to a few hundred MeV, and an elastic scattering cross section with electrons, photons and/or neutrinos in the 10^{-3}-1  fb range.

  12. Asymmetric demand for energy: A cointegration approach

    NASA Astrophysics Data System (ADS)

    Maclean, Thomas Frank

    1997-12-01

    This paper uses time series data in a study of the demand for energy. One goal is to compare the results from the traditional autoregressive distributed lag (ADL) model to the error correction model (ECM) using cointegration. The second goal is to determine if the demand elasticity is asymmetric with respect to increasing and decreasing prices. This paper discusses three topics that are important to the use of time series data. The first topic is the presence and consequences unit roots which are common in time series data. The second topic is the identification of cointegrated variables and the third topic is a development of the ECM. This results in a model that can be used in either a single equation or multivariate system context and it will estimate both long run and short run elasticities. Asymmetry theory and its implications are studied along with an investigation into competing methods of creating the asymmetric variables. Simulations provided evidence that the use of dummy variables results in biased estimates and that the cumulative difference method of Wolffram/Houck gives valid estimates. The results of the empirical part of the paper show that the short run estimates of the ADL model are like those of the error correction model, but the cointegration method's long run estimates are better since they are known to be consistent and asymptotically unbiased. Tests for asymmetry do not support the theory of asymmetric long run price elasticities; however there is evidence to support the presence of asymmetric demand in the short run.

  13. Elastic properties of minerals

    SciTech Connect

    Aleksandrov, K.S.; Prodaivoda, G.T.

    1993-09-01

    Investigations of the elastic properties of the main rock-forming minerals were begun by T.V. Ryzhova and K.S. Aleksandrov over 30 years ago on the initiative of B.P. Belikov. At the time, information on the elasticity of single crystals in general, and especially of minerals, was very scanty. In the surveys of that time there was information on the elasticity of 20 or 30 minerals. These, as a rule, did not include the main rock-forming minerals; silicates were represented only by garnets, quartz, topaz, tourmaline, zircon, beryl, and staurolite, which are often found in nature in the form of large and fairly high-quality crystals. Then and even much later it was still necessary to prove a supposition which now seems obvious: The elastic properties of rocks, and hence the velocities of elastic (seismic) waves in the earth`s crust, are primarily determined by the elastic characteristics of the minerals composing these rocks. Proof of this assertion, with rare exceptions of mono-mineralic rocks (marble, quartzite, etc.) cannot be obtained without information on the elasticities of a sufficiently large number of minerals, primarily framework, layer, and chain silicates which constitute the basis of most rocks. This also served as the starting point and main problem of the undertakings of Aleksandrov, Ryzhova, and Belikov - systematic investigations of the elastic properties of minerals and then of various rocks. 108 refs., 7 tabs.

  14. Electricity demand curtailment planning

    SciTech Connect

    Allentuck, J; Carroll, O; Schnader, M

    1980-01-01

    The state of electricity demand curtailment planning for long term electricity supply disruptions is reviewed. Legal, institutional and technological problems associated with demand curtailment plans are examined, and the existence of well defined social objectives on the part of planners is questioned. A linear programming approach to electricity demand curtailment planning is presented.

  15. Price responsiveness of demand for cigarettes: does rationality matter?

    PubMed

    Laporte, Audrey

    2006-01-01

    Meta-analysis is applied to aggregate-level studies that model the demand for cigarettes using static, myopic, or rational addiction frameworks in an attempt to synthesize key findings in the literature and to identify determinants of the variation in reported price elasticity estimates across studies. The results suggest that the rational addiction framework produces statistically similar estimates to the static framework but that studies that use the myopic framework tend to report more elastic price effects. Studies that applied panel data techniques or controlled for cross-border smuggling reported more elastic price elasticity estimates, whereas the use of instrumental variable techniques and time trends or time dummy variables produced less elastic estimates. The finding that myopic models produce different estimates than either of the other two model frameworks underscores that careful attention must be given to time series properties of the data.

  16. On granular elasticity

    PubMed Central

    Sun, Qicheng; Jin, Feng; Wang, Guangqian; Song, Shixiong; Zhang, Guohua

    2015-01-01

    Mesoscopic structures form in dense granular materials due to the self-organisation of the constituent particles. These structures have internal structural degrees of freedom in addition to the translational degree of freedom. The resultant granular elasticity, which exhibits intrinsic variations and inevitable relaxation, is a key quantity that accounts for macroscopic solid- or fluid-like properties and the transitions between them. In this work, we propose a potential energy landscape (PEL) with local stable basins and low elastic energy barriers to analyse the nature of granular elasticity. A function for the elastic energy density is proposed for stable states and is further calibrated with ultrasonic measurements. Fluctuations in the elastic energy due to the evolution of internal structures are proposed to describe a so-called configuration temperature Tc as a counterpart of the classical kinetic granular temperature Tk that is attributed to the translational degrees of freedom. The two granular temperatures are chosen as the state variables, and a fundamental equation is established to develop non-equilibrium thermodynamics for granular materials. Due to the relatively low elastic energy barrier in the PEL, granular elasticity relaxes more under common mechanical loadings, and a simple model based on mean-field theory is developed to account for this behaviour. PMID:25951049

  17. Demand Response Analysis Tool

    SciTech Connect

    2012-03-01

    Demand Response Analysis Tool is a software developed at the Lawrence Berkeley National Laboratory. It is initially funded by Southern California Edison. Our goal in developing this tool is to provide an online, useable, with standardized methods, an analysis tool to evaluate demand and demand response performance of commercial and industrial facilities. The tool provides load variability and weather sensitivity analysis capabilities as well as development of various types of baselines. It can be used by researchers, real estate management firms, utilities, or any individuals who are interested in analyzing their demand and demand response capabilities.

  18. Elastic membranes in confinement

    NASA Astrophysics Data System (ADS)

    Bostwick, Joshua; Miksis, Michael; Davis, Stephen

    2014-11-01

    An elastic membrane stretched between two walls takes a shape defined by its length and the volume of fluid it encloses. Many biological structures, such as cells, mitochondria and DNA, have finer internal structure in which a membrane (or elastic member) is geometrically ``confined'' by another object. We study the shape stability of elastic membranes in a ``confining'' box and introduce repulsive van der Waals forces to prevent the membrane from intersecting the wall. We aim to define the parameter space associated with mitochondria-like deformations. We compare the confined to `unconfined' solutions and show how the structure and stability of the membrane shapes changes with the system parameters.

  19. Mechanism of Resilin Elasticity

    PubMed Central

    Qin, Guokui; Hu, Xiao; Cebe, Peggy; Kaplan, David L.

    2012-01-01

    Resilin is critical in the flight and jumping systems of insects as a polymeric rubber-like protein with outstanding elasticity. However, insight into the underlying molecular mechanisms responsible for resilin elasticity remains undefined. Here we report the structure and function of resilin from Drosophila CG15920. A reversible beta-turn transition was identified in the peptide encoded by exon III and for full length resilin during energy input and release, features that correlate to the rapid deformation of resilin during functions in vivo. Micellar structures and nano-porous patterns formed after beta-turn structures were present via changes in either the thermal or mechanical inputs. A model is proposed to explain the super elasticity and energy conversion mechanisms of resilin, providing important insight into structure-function relationships for this protein. Further, this model offers a view of elastomeric proteins in general where beta-turn related structures serve as fundamental units of the structure and elasticity. PMID:22893127

  20. Deflation of elastic surfaces

    NASA Astrophysics Data System (ADS)

    Quilliet, Catherine; Quemeneur, François; Marmottant, Philippe; Imhof, Arnout; Pépin-Donat, Brigitte; van Blaaderen, Alfons

    2010-03-01

    The deflation of elastic spherical surfaces has been numerically investigated, and show very different types of deformations according the range of elastic parameters, some of them being quantitatively explained through simple calculations. This allows to retrieve various shapes observed on hollow shells (from colloidal to centimeter scale), on lipid vesicles, or on some biological objects. The extension of this process to other geometries allows to modelize vegetal objects such as the ultrafast trap of carnivorous plants.

  1. Elasticity of plagioclase feldspars

    NASA Astrophysics Data System (ADS)

    Brown, J. Michael; Angel, Ross J.; Ross, Nancy L.

    2016-02-01

    Elastic properties are reported for eight plagioclase feldspars that span compositions from albite (NaSi3AlO8) to anorthite (CaSi2Al2O8). Surface acoustic wave velocities measured using Impulsive Stimulated Light Scattering and compliance sums from high-pressure X-ray compression studies accurately determine all 21 components of the elasticity tensor for these triclinic minerals. The overall pattern of elasticity and the changes in individual elastic components with composition can be rationalized on the basis of the evolution of crystal structures and chemistry across this solid-solution join. All plagioclase feldspars have high elastic anisotropy; a* (the direction perpendicular to the b and c axes) is the softest direction by a factor of 3 in albite. From albite to anorthite the stiffness of this direction undergoes the greatest change, increasing twofold. Small discontinuities in the elastic components, inferred to occur between the three plagioclase phases with distinct symmetry (C1>¯, I1>¯, and P1>¯), appear consistent with the nature of the underlying conformation of the framework-linked tetrahedra and the associated structural changes. Measured body wave velocities of plagioclase-rich rocks, reported over the last five decades, are consistent with calculated Hill-averaged velocities using the current moduli. This confirms long-standing speculation that previously reported elastic moduli for plagioclase feldspars are systematically in error. The current results provide greater assurance that the seismic structure of the middle and lower crusts can be accurately estimated on the basis of specified mineral modes, chemistry, and fabric.

  2. A comparison of economic demand and conditioned-cued reinstatement of methamphetamine-seeking or food-seeking in rats.

    PubMed

    Galuska, Chad M; Banna, Kelly M; Willse, Lena Vaughn; Yahyavi-Firouz-Abadi, Noushin; See, Ronald E

    2011-08-01

    This study examined whether continued access to methamphetamine or food reinforcement changed economic demand for both. The relationship between demand elasticity and cue-induced reinstatement was also determined. Male Long-Evans rats were lever pressed under increasing fixed-ratio requirements for either food pellets or methamphetamine (20 μg/50 μl infusion). For two groups, demand curves were obtained before and after continued access (12 days, 2-h sessions) to the reinforcer under a fixed-ratio 3 schedule. A third group was given continued access to methamphetamine between determinations of food demand and a fourth group abstained from methamphetamine between determinations. All groups underwent extinction sessions, followed by a cue-induced reinstatement test. Although food demand was less elastic than methamphetamine demand, continued access to methamphetamine shifted the methamphetamine demand curve upward and the food demand curve downward. In some rats, methamphetamine demand also became less elastic. Continued access to food had no effect on food demand. Reinstatement was higher after continued access to methamphetamine relative to food. For methamphetamine, elasticity and reinstatement measures were correlated. Continued access to methamphetamine, but not food, alters demand in ways suggestive of methamphetamine accruing reinforcing strength. Demand elasticity thus provides a useful measure of abuse liability that may predict future relapse to renewed drug-seeking and drug use.

  3. Elastic properties of pyrope

    NASA Astrophysics Data System (ADS)

    O'Neill, Bridget; Bass, Jay D.; Rossman, George R.; Geiger, Charles A.; Langer, Klaus

    1991-03-01

    Brillouin spectroscopy was used to measure the single crystal elastic properties of a pure synthetic pyrope and a natural garnet containing 89.9 mol% of the pyrope end member (Mg3Al2Si3O12). The elastic moduli, c ij , of the two samples are entirely consistent and agree with previous estimates of the elastic properties of pyrope based upon the moduli of solid solutions. Our results indicate that the elastic moduli of pyrope end-member are c 11=296.2±0.5, c 12=111.1±0.6, c 44=91.6±0.3, Ks=172.8±0.3, μ=92.0±0.2, all in units of GPa. These results differ by several percent from those reported previously for synthetic pyrope, but are based upon a much larger data set. Although the hydrous components of the two samples from the present study are substantially different, representing both ‘dry’ and ‘saturated’ samples, we find no discernable effect of structurally bound water on the elastic properties. This is due to the small absolute solubility of water in pyrope, as compared with other garnets such as grossular.

  4. Estimating Price Elasticity using Market-Level Appliance Data

    SciTech Connect

    Fujita, K. Sydny

    2015-08-04

    This report provides and update to and expansion upon our 2008 LBNL report “An Analysis of the Price Elasticity of Demand for Appliances,” in which we estimated an average relative price elasticity of -0.34 for major household appliances (Dale and Fujita 2008). Consumer responsiveness to price change is a key component of energy efficiency policy analysis; these policies influence consumer purchases through price both explicitly and implicitly. However, few studies address appliance demand elasticity in the U.S. market and public data sources are generally insufficient for rigorous estimation. Therefore, analysts have relied on a small set of outdated papers focused on limited appliance types, assuming long-term elasticities estimated for other durables (e.g., vehicles) decades ago are applicable to current and future appliance purchasing behavior. We aim to partially rectify this problem in the context of appliance efficiency standards by revisiting our previous analysis, utilizing data released over the last ten years and identifying additional estimates of durable goods price elasticities in the literature. Reviewing the literature, we find the following ranges of market-level price elasticities: -0.14 to -0.42 for appliances; -0.30 to -1.28 for automobiles; -0.47 to -2.55 for other durable goods. Brand price elasticities are substantially higher for these product groups, with most estimates -2.0 or more elastic. Using market-level shipments, sales value, and efficiency level data for 1989-2009, we run various iterations of a log-log regression model, arriving at a recommended range of short run appliance price elasticity between -0.4 and -0.5, with a default value of -0.45.

  5. An elastic second skin

    NASA Astrophysics Data System (ADS)

    Yu, Betty; Kang, Soo-Young; Akthakul, Ariya; Ramadurai, Nithin; Pilkenton, Morgan; Patel, Alpesh; Nashat, Amir; Anderson, Daniel G.; Sakamoto, Fernanda H.; Gilchrest, Barbara A.; Anderson, R. Rox; Langer, Robert

    2016-08-01

    We report the synthesis and application of an elastic, wearable crosslinked polymer layer (XPL) that mimics the properties of normal, youthful skin. XPL is made of a tunable polysiloxane-based material that can be engineered with specific elasticity, contractility, adhesion, tensile strength and occlusivity. XPL can be topically applied, rapidly curing at the skin interface without the need for heat- or light-mediated activation. In a pilot human study, we examined the performance of a prototype XPL that has a tensile modulus matching normal skin responses at low strain (<40%), and that withstands elongations exceeding 250%, elastically recoiling with minimal strain-energy loss on repeated deformation. The application of XPL to the herniated lower eyelid fat pads of 12 subjects resulted in an average 2-grade decrease in herniation appearance in a 5-point severity scale. The XPL platform may offer advanced solutions to compromised skin barrier function, pharmaceutical delivery and wound dressings.

  6. Elastic constants of calcite

    USGS Publications Warehouse

    Peselnick, L.; Robie, R.A.

    1962-01-01

    The recent measurements of the elastic constants of calcite by Reddy and Subrahmanyam (1960) disagree with the values obtained independently by Voigt (1910) and Bhimasenachar (1945). The present authors, using an ultrasonic pulse technique at 3 Mc and 25??C, determined the elastic constants of calcite using the exact equations governing the wave velocities in the single crystal. The results are C11=13.7, C33=8.11, C44=3.50, C12=4.82, C13=5.68, and C14=-2.00, in units of 1011 dyncm2. Independent checks of several of the elastic constants were made employing other directions and polarizations of the wave velocities. With the exception of C13, these values substantially agree with the data of Voigt and Bhimasenachar. ?? 1962 The American Institute of Physics.

  7. Elastic model of supercoiling.

    PubMed Central

    Benham, C J

    1977-01-01

    An elastic model for the supercoiling of duplex DNA is developed. The simplest assumptions regarding the elastic properties of double-helical DNA (homogeneous, isotropic, of circular cross section, and remaining straight when unstressed) will generate two orders of superhelicity when stressed. Recent experimental results [Brady, G.W., Fein, D.B. & Brumberger, H. (1976) Nature 264, 231-234] suggest that in supercoiled DNA molecules there are regions where two distinct orders of supercoiling arise, as predicted by this model. PMID:267934

  8. A Review of Two Studies of Elasticity in Academe.

    ERIC Educational Resources Information Center

    Hoffman, Emily P.

    1986-01-01

    Reviews two elasticity of demand papers in this "Economics of Education Review" issue. Refutes C.F. Chang and H.P. Tuckman's interpretation of college faculty substitution trends, attributing changes in rank distribution to academic hiring and promotion patterns. Affirms G.A. Chressanthis' class standing results and recommendation of a…

  9. Circulation Price Elasticity in the Daily Newspaper Industry.

    ERIC Educational Resources Information Center

    Grotta, Gerald L.; Taylor, Michael Lee

    Pricing of subscriptions and single copies has historically been arbitrary. Evidence indicates that the newspaper industry has tended to overestimate the elasticity of demand for newspaper circulation. This study analyzed price changes, circulation changes, and population changes for all daily newspapers in the United States between 1970 and 1975.…

  10. Slope versus Elasticity and the Burden of Taxation.

    ERIC Educational Resources Information Center

    Graves, Philip E.; And Others

    1996-01-01

    Criticizes the standard presentation, in introductory economics, of the burden of a tax as an application of elasticity. Argues that using the slopes of a supply and demand curve is the simplest and easiest way to clarify tax incidence. Includes three graphs illustrating this approach. (MJP)

  11. Demand impact and policy implications from taxing nitrogen fertilizer

    SciTech Connect

    Foltz, J.C.

    1992-12-01

    Recent concern has focused on nitrogen fertilizer as a potential contaminant of groundwater. A demand function for fertilizer was developed using the quantity of fertilizer purchased, corn yield, real price of nitrogen fertilizer, lagged fertilizer purchases, a land value variable and the real price of corn as explanatory variables. Short and long-run price elasticities of demand were estimated to be inelastic. Support was found for the hypothesis that demand for nitrogen fertilizer has become more price inelastic over time. From a policy standpoint, a tax on nitrogen fertilizer may not be the most effective method to reduce consumption.

  12. Impact of Energy Demands

    ERIC Educational Resources Information Center

    Cambel, Ali B.

    1970-01-01

    The types of pollutants associated with the process of power production are identified. A nine-point proposal is presented on the ways the increase in power demands might be achieved with the minimum threat to the environment. (PR)

  13. Latin American demand

    SciTech Connect

    1994-12-01

    From Mexico to Argentina, independent power companies are finding great demand for their services in Latin America. But while legal and economic conditions are increasingly favorable, political and financial uncertainties make power development challenging.

  14. The Law of Elasticity

    ERIC Educational Resources Information Center

    Cocco, Alberto; Masin, Sergio Cesare

    2010-01-01

    Participants estimated the imagined elongation of a spring while they were imagining that a load was stretching the spring. This elongation turned out to be a multiplicative function of spring length and load weight--a cognitive law analogous to Hooke's law of elasticity. Participants also estimated the total imagined elongation of springs joined…

  15. Elastic swimming I: Optimization

    NASA Astrophysics Data System (ADS)

    Lauga, Eric; Yu, Tony; Hosoi, Anette

    2006-03-01

    We consider the problem of swimming at low Reynolds number by oscillating an elastic filament in a viscous liquid, as investigated by Wiggins and Goldstein (1998, Phys Rev Lett). In this first part of the study, we characterize the optimal forcing conditions of the swimming strategy and its optimal geometrical characteristics.

  16. Elastic swimming II: Experiments

    NASA Astrophysics Data System (ADS)

    Yu, Tony; Lauga, Eric; Hosoi, Anette

    2006-03-01

    We consider the problem of swimming at low Reynolds number by oscillating an elastic filament in a viscous liquid, as investigated by Wiggins and Goldstein (1998, Phys Rev Lett). In this second part of the study, we present results of a series of experiments characterizing the performance of the propulsive mechanism.

  17. Hydrodynamic Elastic Magneto Plastic

    SciTech Connect

    Wilkins, M. L.; Levatin, J. A.

    1985-02-01

    The HEMP code solves the conservation equations of two-dimensional elastic-plastic flow, in plane x-y coordinates or in cylindrical symmetry around the x-axis. Provisions for calculation of fixed boundaries, free surfaces, pistons, and boundary slide planes have been included, along with other special conditions.

  18. Elastic and Inelastic Collisions

    ERIC Educational Resources Information Center

    Gluck, Paul

    2010-01-01

    There have been two articles in this journal that described a pair of collision carts used to demonstrate vividly the difference between elastic and inelastic collisions. One cart had a series of washers that were mounted rigidly on a rigid wooden framework, the other had washers mounted on rubber bands stretched across a framework. The rigidly…

  19. Demand Response Dispatch Tool

    SciTech Connect

    2012-08-31

    The Demand Response (DR) Dispatch Tool uses price profiles to dispatch demand response resources and create load modifying profiles. These annual profiles are used as inputs to production cost models and regional planning tools (e.g., PROMOD). The tool has been effectively implemented in transmission planning studies conducted by the Western Electricity Coordinating Council via its Transmission Expansion Planning and Policy Committee. The DR Dispatch Tool can properly model the dispatch of DR resources for both reliability and economic conditions.

  20. Elastic Granular Flows

    NASA Astrophysics Data System (ADS)

    Campbell, Charles

    2006-03-01

    There is no fundamental understanding of the mechanics of granular solids. Partially this is because granular flows have historically been divided into two very distinct flow regimes, (1) the slow, quasistatic regime, in which the bulk friction coefficient is taken to be a material constant, and (2) the fast, rapid-flow regime, where the particles interact collisionally. But slow hopper flow simulations indicate that the bulk friction coefficient is not a constant. Rapidly moving large scale landslide simulations never entered the collisional regime and operate in a separate intermediate flow regime. In other words, most realistic granular flows are not described by either the quasistatic or rapid flow models and it is high time that the field look beyond those early models. This talk will discuss computer simulation studies that draw out the entire flowmap of shearing granular materials, spanning the quasistatic, rapid and the intermediate regimes. The key was to include the elastic properties of the solid material in the set of rheological parameters; in effect, this puts solid properties back into the rheology of granular solids. The solid properties were previously unnecessary in the plasticity and kinetic theory formalisms that respectively form the foundations of the quasistatic and rapid-flow theories. Granular flows can now be divided into two broad categories, the Elastic Regimes, in which the particles are locked in force chains and interact elastically over long duration contact with their neighbors and the Inertial regimes, where the particles have broken free of the force chains. The Elastic regimes can be further subdivided into the Elastic-Quasistatic regime (the old quasistatic regime) and the Elastic-Inertial regime. The Elastic-Inertial regime is the ``new'' regime observed in the landslide simulations, in which the inertially induced stresses are significant compared to the elastically induced stresses. The Inertial regime can also be sub

  1. Nonlinear theoretical formulation of elastic stability criterion of crystal solids

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Li, Mo

    2012-03-01

    An elastic stability criterion is generally formulated based on local elasticity, where the second-order elastic constants of a crystalline system in an arbitrary deformed state are required. While simple in formalism, such a formulation demands extensive computational effort in either an ab initio calculation or an atomistic simulation and often lacks clear physical interpretation. Here, we present a nonlinear theoretical formulation employing higher-order elastic constants beyond the second-order ones; the elastic constants needed in the theory are those at a zero stress state or in any arbitrary deformed state, many of which are now available. We use the published second- and higher-order elastic constants of several cubic crystals, including Au, Al, and Cu, as well as diamond-structure Si, with transcription under different coordinate frames, to test the stability conditions of these crystals under uniaxial and hydrostatic loading. The stability region, ideal strength, and potential bifurcation mode of those cubic crystals under loading are obtained using this theory. The results obtained are in good agreement with the results from the ab initio calculation or embedded atom method. The overall good quality of the results confirms the desired utility of this new approach to predict elastic stability and related properties of crystalline materials without involving intense computation.

  2. Efficiency gain from elastic optical networks

    NASA Astrophysics Data System (ADS)

    Morea, Annalisa; Rival, Olivier

    2011-12-01

    We compare the cost-efficiency of optical networks based on mixed datarates (10, 40, 100Gb/s) and datarateelastic technologies. A European backbone network is examined under various traffic assumptions (volume of transported data per demand and total number of demands) to better understand the impact of traffic characteristics on cost-efficiency. Network dimensioning is performed for static and restorable networks (resilient to one-link failure). In this paper we will investigate the trade-offs between price of interfaces, reach and reconfigurability, showing that elastic solutions can be more cost-efficient than mixed-rate solutions because of the better compatibility between different datarates, increased reach of channels and simplified wavelength allocation.

  3. Demand for oil and energy in developing countries

    SciTech Connect

    Wolf, C. Jr.; Relles, D.A.; Navarro, J.

    1980-05-01

    How much of the world's oil and energy supply will the non-OPEC less-developed countries (NOLDCs) demand in the next decade. Will their requirements be small and thus fairly insignificant compared with world demand, or large and relatively important. How will world demand be affected by the economic growth of the NOLDCs. In this report, we try to develop some reasonable forecasts of NOLDC energy demands in the next 10 years. Our focus is mainly on the demand for oil, but we also give some attention to the total commercial energy requirements of these countries. We have tried to be explicit about the uncertainties associated with our forecasts, and with the income and price elasticities on which they are based. Finally, we consider the forecasts in terms of their implications for US policies concerning the NOLDCs and suggest areas of future research on NOLDC energy issues.

  4. Linear Elastic Waves

    NASA Astrophysics Data System (ADS)

    Revenough, Justin

    Elastic waves propagating in simple media manifest a surprisingly rich collection of phenomena. Although some can't withstand the complexities of Earth's structure, the majority only grow more interesting and more important as remote sensing probes for seismologists studying the planet's interior. To fully mine the information carried to the surface by seismic waves, seismologists must produce accurate models of the waves. Great strides have been made in this regard. Problems that were entirely intractable a decade ago are now routinely solved on inexpensive workstations. The mathematical representations of waves coded into algorithms have grown vastly more sophisticated and are troubled by many fewer approximations, enforced symmetries, and limitations. They are far from straightforward, and seismologists using them need a firm grasp on wave propagation in simple media. Linear Elastic Waves, by applied mathematician John G. Harris, responds to this need.

  5. Series elastic actuators

    NASA Astrophysics Data System (ADS)

    Williamson, Matthew M.

    1995-01-01

    This thesis presents the design, construction, control and evaluation of a novel for controlled actuator. Traditional force controlled actuators are designed from the premise that 'Stiffer is better'. This approach gives a high bandwidth system, prone to problems of contact instability, noise, and low power density. The actuator presented in this thesis is designed from the premise that 'Stiffness isn't everything'. The actuator, which incorporates a series elastic element, trades off achievable bandwidth for gains in stable, low noise force control, and protection against shock loads. This thesis reviews related work in robot force control, presents theoretical descriptions of the control and expected performance from a series elastic actuator, and describes the design of a test actuator constructed to gather performance data. Finally the performance of the system is evaluated by comparing the performance data to theoretical predictions.

  6. Elastic plate spallation

    NASA Technical Reports Server (NTRS)

    Oline, L.; Medaglia, J.

    1972-01-01

    The dynamic finite element method was used to investigate elastic stress waves in a plate. Strain displacement and stress strain relations are discussed along with the stiffness and mass matrix. The results of studying point load, and distributed load over small, intermediate, and large radii are reported. The derivation of finite element matrices, and the derivation of lumped and consistent matrices for one dimensional problems with Laplace transfer solutions are included. The computer program JMMSPALL is also included.

  7. Community Colleges and Labor Market Conditions: How Does Enrollment Demand Change Relative to Local Unemployment Rates?

    ERIC Educational Resources Information Center

    Hillman, Nicholas W.; Orians, Erica Lee

    2013-01-01

    This study uses fixed-effects panel data techniques to estimate the elasticity of community college enrollment demand relative to local unemployment rates. The findings suggest that community college enrollment demand is counter-cyclical to changes in the labor market, as enrollments rise during periods of weak economic conditions. Using national…

  8. Travel Demand Modeling

    SciTech Connect

    Southworth, Frank; Garrow, Dr. Laurie

    2011-01-01

    This chapter describes the principal types of both passenger and freight demand models in use today, providing a brief history of model development supported by references to a number of popular texts on the subject, and directing the reader to papers covering some of the more recent technical developments in the area. Over the past half century a variety of methods have been used to estimate and forecast travel demands, drawing concepts from economic/utility maximization theory, transportation system optimization and spatial interaction theory, using and often combining solution techniques as varied as Box-Jenkins methods, non-linear multivariate regression, non-linear mathematical programming, and agent-based microsimulation.

  9. Demanding Divestment from Sudan

    ERIC Educational Resources Information Center

    Asquith, Christina

    2006-01-01

    Bowing to student demands to "stop supporting genocide," the University of California regents voted earlier this year to divest millions of dollars from companies working in the war-torn African nation of Sudan, the first major public university in the nation to take such action. Since student protests on the subject began at Harvard…

  10. Demand, Growth, and Evolution

    ERIC Educational Resources Information Center

    Hoskins, Barbara

    2011-01-01

    The paradigm shift to engaged and collaborative learning delivered via distance education technologies has been led by practitioners in adult and continuing education. Online and blended courses are experiencing increased demand and continued growth at all levels of higher education, professional development, and K-12 education. Adult and…

  11. Probabilistic elastography: estimating lung elasticity.

    PubMed

    Risholm, Petter; Ross, James; Washko, George R; Wells, William M

    2011-01-01

    We formulate registration-based elastography in a probabilistic framework and apply it to study lung elasticity in the presence of emphysematous and fibrotic tissue. The elasticity calculations are based on a Finite Element discretization of a linear elastic biomechanical model. We marginalize over the boundary conditions (deformation) of the biomechanical model to determine the posterior distribution over elasticity parameters. Image similarity is included in the likelihood, an elastic prior is included to constrain the boundary conditions, while a Markov model is used to spatially smooth the inhomogeneous elasticity. We use a Markov Chain Monte Carlo (MCMC) technique to characterize the posterior distribution over elasticity from which we extract the most probable elasticity as well as the uncertainty of this estimate. Even though registration-based lung elastography with inhomogeneous elasticity is challenging due the problem's highly underdetermined nature and the sparse image information available in lung CT, we show promising preliminary results on estimating lung elasticity contrast in the presence of emphysematous and fibrotic tissue.

  12. Demand Responsive Lighting: A Scoping Study

    SciTech Connect

    Rubinstein, Francis; Kiliccote, Sila

    2007-01-03

    increased awareness of the need to standardize on emerging wireless technologies are evidence of this transformation. In addition to increased standardization of digital control protocols controller capabilities, the lighting industry has improved the performance of dimming lighting systems over the last two years. The system efficacy of today's current dimming ballasts is approaching that of non-dimming program start ballasts. The study finds that the benefits of applying digital controls technologies to California's unique commercial buildings market are enormous. If California were to embark on an concerted 20 year program to improve the demand responsiveness and energy efficiency of commercial building lighting systems, the State could avoid adding generation capacity, improve the elasticity of the grid, save Californians billion of dollars in avoided energy charges and significantly reduce greenhouse gas emissions.

  13. Demand surge following earthquakes

    USGS Publications Warehouse

    Olsen, Anna H.

    2012-01-01

    Demand surge is understood to be a socio-economic phenomenon where repair costs for the same damage are higher after large- versus small-scale natural disasters. It has reportedly increased monetary losses by 20 to 50%. In previous work, a model for the increased costs of reconstruction labor and materials was developed for hurricanes in the Southeast United States. The model showed that labor cost increases, rather than the material component, drove the total repair cost increases, and this finding could be extended to earthquakes. A study of past large-scale disasters suggested that there may be additional explanations for demand surge. Two such explanations specific to earthquakes are the exclusion of insurance coverage for earthquake damage and possible concurrent causation of damage from an earthquake followed by fire or tsunami. Additional research into these aspects might provide a better explanation for increased monetary losses after large- vs. small-scale earthquakes.

  14. Design guidance for elastic followup

    SciTech Connect

    Naugle, F.V.

    1983-01-01

    The basic mechanism of elastic followup is discussed in relation to piping design. It is shown how mechanistic insight gained from solutions for a two-bar problem can be used to identify dominant design parameters and to determine appropriate modifications where elastic followup is a potential problem. It is generally recognized that quantitative criteria are needed for elastic followup in the creep range where badly unbalanced lines can pose potential problems. Approaches for criteria development are discussed.

  15. Theory of epithelial elasticity

    NASA Astrophysics Data System (ADS)

    Krajnc, Matej; Ziherl, Primož

    2015-11-01

    We propose an elastic theory of epithelial monolayers based on a two-dimensional discrete model of dropletlike cells characterized by differential surface tensions of their apical, basal, and lateral sides. We show that the effective tissue bending modulus depends on the apicobasal differential tension and changes sign at the transition from the flat to the fold morphology. We discuss three mechanisms that stabilize the finite-wavelength fold structures: Physical constraint on cell geometry, hard-core interaction between non-neighboring cells, and bending elasticity of the basement membrane. We show that the thickness of the monolayer changes along the waveform and thus needs to be considered as a variable rather than a parameter. Next we show that the coupling between the curvature and the thickness is governed by the apicobasal polarity and that the amplitude of thickness modulation along the waveform is proportional to the apicobasal differential tension. This suggests that intracellular stresses can be measured indirectly by observing easily measurable morphometric parameters. We also study the mechanics of three-dimensional structures with cylindrical symmetry.

  16. Elastic emission polishing

    SciTech Connect

    Loewenthal, M.; Loseke, K.; Dow, T.A.; Scattergood, R.O.

    1988-12-01

    Elastic emission polishing, also called elastic emission machining (EEM), is a process where a stream of abrasive slurry is used to remove material from a substrate and produce damage free surfaces with controlled surface form. It is a noncontacting method utilizing a thick elasto-hydrodynamic film formed between a soft rotating ball and the workpiece to control the flow of the abrasive. An apparatus was built in the Center, which consists of a stationary spindle, a two-axis table for the workpiece, and a pump to circulate the working fluid. The process is controlled by a programmable computer numerical controller (CNC), which presently can operate the spindle speed and movement of the workpiece in one axis only. This apparatus has been used to determine material removal rates on different material samples as a function of time, utilizing zirconium oxide (ZrO{sub 2}) particles suspended in distilled water as the working fluid. By continuing a study of removal rates the process should become predictable, and thus create a new, effective, yet simple tool for ultra-precision mechanical machining of surfaces.

  17. MODELING THE DEMAND FOR E85 IN THE UNITED STATES

    SciTech Connect

    Liu, Changzheng; Greene, David L

    2013-10-01

    How demand for E85 might evolve in the future in response to changing economics and policies is an important subject to include in the National Energy Modeling System (NEMS). This report summarizes a study to develop an E85 choice model for NEMS. Using the most recent data from the states of Minnesota, North Dakota, and Iowa, this study estimates a logit model that represents E85 choice as a function of prices of E10 and E85, as well as fuel availability of E85 relative to gasoline. Using more recent data than previous studies allows a better estimation of non-fleet demand and indicates that the price elasticity of E85 choice appears to be higher than previously estimated. Based on the results of the econometric analysis, a model for projecting E85 demand at the regional level is specified. In testing, the model produced plausible predictions of US E85 demand to 2040.

  18. Accounting for Water Insecurity in Modeling Domestic Water Demand

    NASA Astrophysics Data System (ADS)

    Galaitsis, S. E.; Huber-lee, A. T.; Vogel, R. M.; Naumova, E.

    2013-12-01

    Water demand management uses price elasticity estimates to predict consumer demand in relation to water pricing changes, but studies have shown that many additional factors effect water consumption. Development scholars document the need for water security, however, much of the water security literature focuses on broad policies which can influence water demand. Previous domestic water demand studies have not considered how water security can affect a population's consumption behavior. This study is the first to model the influence of water insecurity on water demand. A subjective indicator scale measuring water insecurity among consumers in the Palestinian West Bank is developed and included as a variable to explore how perceptions of control, or lack thereof, impact consumption behavior and resulting estimates of price elasticity. A multivariate regression model demonstrates the significance of a water insecurity variable for data sets encompassing disparate water access. When accounting for insecurity, the R-squaed value improves and the marginal price a household is willing to pay becomes a significant predictor for the household quantity consumption. The model denotes that, with all other variables held equal, a household will buy more water when the users are more water insecure. Though the reasons behind this trend require further study, the findings suggest broad policy implications by demonstrating that water distribution practices in scarcity conditions can promote consumer welfare and efficient water use.

  19. Factor Demand Theory Under Perfect Competition, Monopoly, and Monopsony,

    DTIC Science & Technology

    1974-10-01

    MC(p 1,. . . , p , q *) = 0 (13) and -~~~~~~~ > 0. Holding p constant and different iat ing Eq. (13) as an f implicit function yields -~~~\\I...Charles , and C. E. Ferguson , “Factor Demand Elasticity under Monopoly and Monopsony ,” Economica , Vol. 40, May 19-73, pp. 180— 186. -• [5] Sato

  20. A unique formulation of elastic airplane longitudinal equations of motion

    NASA Technical Reports Server (NTRS)

    Swaim, R. L.; Fullman, D. G.

    1976-01-01

    Control-configured vehicle technology has increased the demand for detailed analysis of dynamic stability and control, handling and ride qualities, and control system dynamics at early stages of preliminary design. An approximate, but reasonably accurate, set of equations of motion are needed for these early analyses. Such a formulation is developed for the longitudinal dynamics of elastic airplanes. It makes use of only rigid-body aerodynamic stability derivatives in formulating the forces and moments due to elastic motion. Verification of accuracy using data for the B-1 airplane shows very good agreement. Frequencies and damping ratios of the coupled modes corresponding to complex roots of the characteristic equations agree closely with four symmetric elastic modes included.

  1. Dividends with Demand Response

    SciTech Connect

    Kintner-Meyer, Michael CW; Goldman, Charles; Sezgen, O.; Pratt, D.

    2003-10-31

    To assist facility managers in assessing whether and to what extent they should participate in demand response programs offered by ISOs, we introduce a systematic process by which a curtailment supply curve can be developed that integrates costs and other program provisions and features. This curtailment supply curve functions as bid curve, which allows the facility manager to incrementally offer load to the market under terms and conditions acceptable to the customer. We applied this load curtailment assessment process to a stylized example of an office building, using programs offered by NYISO to provide detail and realism.

  2. Elastic instabilities in rubber

    NASA Astrophysics Data System (ADS)

    Gent, Alan

    2009-03-01

    Materials that undergo large elastic deformations can exhibit novel instabilities. Several examples are described: development of an aneurysm on inflating a rubber tube; non-uniform stretching on inflating a spherical balloon; formation of internal cracks in rubber blocks at a critical level of triaxial tension or when supersaturated with a dissolved gas; surface wrinkling of a block at a critical amount of compression; debonding or fracture of constrained films on swelling, and formation of ``knots'' on twisting stretched cylindrical rods. These various deformations are analyzed in terms of a simple strain energy function, using Rivlin's theory of large elastic deformations, and the results are compared with experimental measurements of the onset of unstable states. Such comparisons provide new tests of Rivlin's theory and, at least in principle, critical tests of proposed strain energy functions for rubber. Moreover the onset of highly non-uniform deformations has serious implications for the fatigue life and fracture resistance of rubber components. [4pt] References: [0pt] R. S. Rivlin, Philos. Trans. Roy. Soc. Lond. Ser. A241 (1948) 379--397. [0pt] A. Mallock, Proc. Roy. Soc. Lond. 49 (1890--1891) 458--463. [0pt] M. A. Biot, ``Mechanics of Incremental Deformations'', Wiley, New York, 1965. [0pt] A. N. Gent and P. B. Lindley, Proc. Roy. Soc. Lond. A 249 (1958) 195--205. [0pt] A. N. Gent, W. J. Hung and M. F. Tse, Rubb. Chem. Technol. 74 (2001) 89--99. [0pt] A. N. Gent, Internatl. J. Non-Linear Mech. 40 (2005) 165--175.

  3. Renewable Energy Resources Portfolio Optimization in the Presence of Demand Response

    SciTech Connect

    Behboodi, Sahand; Chassin, David P.; Crawford, Curran; Djilali, Ned

    2016-01-15

    In this paper we introduce a simple cost model of renewable integration and demand response that can be used to determine the optimal mix of generation and demand response resources. The model includes production cost, demand elasticity, uncertainty costs, capacity expansion costs, retirement and mothballing costs, and wind variability impacts to determine the hourly cost and revenue of electricity delivery. The model is tested on the 2024 planning case for British Columbia and we find that cost is minimized with about 31% renewable generation. We also find that demand responsive does not have a significant impact on cost at the hourly level. The results suggest that the optimal level of renewable resource is not sensitive to a carbon tax or demand elasticity, but it is highly sensitive to the renewable resource installation cost.

  4. The First Law of Elasticity

    ERIC Educational Resources Information Center

    Girill, T. R.

    1972-01-01

    The Boyle-Mariotte gas law was formulated in terms of pneumatic springs," subsumed by Hooke under his own stress-strain relation, and generally regarded as a law of elasticity. The subsequent development of Boyle's principle and elasticity provide thought-provoking test cases for Kuhn's notations of paradigm and puzzle solving in physics.…

  5. Valve designed with elastic seat

    NASA Technical Reports Server (NTRS)

    Mac Glashan, W. F., Jr.

    1965-01-01

    Absolute valve closure is accomplished by a machined valve with an axially annular channel which changes the outlet passage into a thin tubular elastic seat member with a retainer backup ring. The elasticity of the seat provides tight conformity to ball irregularity.

  6. PAGOSA Sample Problem. Elastic Precursor

    SciTech Connect

    Weseloh, Wayne N.; Clancy, Sean Patrick

    2016-02-03

    A PAGOSA simulation of a flyer plate impact which produces an elastic precursor wave is examined. The simulation is compared to an analytic theory for the Mie-Grüneisen equation of state and an elastic-perfectly-plastic strength model.

  7. Elasticity of Flowing Soap films

    NASA Astrophysics Data System (ADS)

    Kim, Ildoo; Mandre, Shreyas

    2016-11-01

    The robustness of soap films and bubbles manifests their mechanical stability. The single most important factor underlying the mechanical stability of soap films is its elasticity. Non-destructive measurement of the elasticity in these films has been cumbersome, because of its flowing nature. Here we provide a convenient, reproducible, and non-destructive method for measuring the elasticity by generating and inspecting Marangoni waves. Our method is based on generating an oblique shock by inserting a thin cylindrical obstacle in the flowing film, and converting the measured the shock angle to elasticity. Using this method, we find a constant value for the elasticity of 22 dyne/cm in the commonly used range of film widths, thicknesses or flow rates, implying that the surface of the film is chemically saturated with soap molecules.

  8. An empirical analysis of cigarette demand in Argentina

    PubMed Central

    Martinez, Eugenio; Mejia, Raul; Pérez-Stable, Eliseo J

    2014-01-01

    Objective To estimate the long-term and short-term effects on cigarette demand in Argentina based on changes in cigarette price and income per person >14 years old. Method Public data from the Ministry of Economics and Production were analysed based on monthly time series data between 1994 and 2010. The econometric analysis used cigarette consumption per person >14 years of age as the dependent variable and the real income per person >14 years old and the real average price of cigarettes as independent variables. Empirical analyses were done to verify the order of integration of the variables, to test for cointegration to capture the long-term effects and to capture the short-term dynamics of the variables. Results The demand for cigarettes in Argentina was affected by changes in real income and the real average price of cigarettes. The long-term income elasticity was equal to 0.43, while the own-price elasticity was equal to −0.31, indicating a 10% increase in the growth of real income led to an increase in cigarette consumption of 4.3% and a 10% increase in the price produced a fall of 3.1% in cigarette consumption. The vector error correction model estimated that the short-term income elasticity was 0.25 and the short-term own-price elasticity of cigarette demand was −0.15. A simulation exercise showed that increasing the price of cigarettes by 110% would maximise revenues and result in a potentially large decrease in total cigarette consumption. Conclusion Econometric analyses of cigarette consumption and their relationship with cigarette price and income can provide valuable information for developing cigarette price policy. PMID:23760657

  9. Grower demand for sensor-controlled irrigation

    NASA Astrophysics Data System (ADS)

    Lichtenberg, Erik; Majsztrik, John; Saavoss, Monica

    2015-01-01

    Water scarcity is likely to increase in the coming years, making improvements in irrigation efficiency increasingly important. An emerging technology that promises to increase irrigation efficiency substantially is a wireless irrigation sensor network that uploads sensor data into irrigation management software, creating an integrated system that allows real-time monitoring and control of moisture status that has been shown in experimental settings to reduce irrigation costs, lower plant loss rates, shorten production times, decrease pesticide application, and increase yield, quality, and profit. We use an original survey to investigate likely initial acceptance, ceiling adoption rates, and profitability of this new sensor network technology in the nursery and greenhouse industry. We find that adoption rates for a base system and demand for expansion components are decreasing in price, as expected. The price elasticity of the probability of adoption suggests that sensor networks are likely to diffuse at a rate somewhat greater than that of drip irrigation. Adoption rates for a base system and demand for expansion components are increasing in specialization in ornamental production: growers earning greater shares of revenue from greenhouse and nursery operations are willing to pay more for a base system and are willing to purchase larger numbers of expansion components at any given price. We estimate that growers who are willing to purchase a sensor network expect investment in this technology to generate significant profit, consistent with findings from experimental studies.

  10. Elastic protectors for ultrasound injection

    SciTech Connect

    Barkhatov, V.A.; Nesterova, L.A.

    1995-07-01

    A new material has been developed for elastic protectors on ultrasonic probes: sonar rubber. This combines low ultrasonic absorption, high strength, and wear resistance, and so the rubber can be used in sensor designs.

  11. Measuring How Elastic Arteries Function.

    ERIC Educational Resources Information Center

    DeMont, M. Edwin; MacGillivray, Patrick S.; Davison, Ian G.; McConnell, Colin J.

    1997-01-01

    Describes a procedure used to measure force and pressure in elastic arteries. Discusses the physics of the procedure and recommends the use of bovine arteries. Explains the preparation of the arteries for the procedure. (DDR)

  12. Elasticity of crystalline molecular explosives

    DOE PAGES

    Hooks, Daniel E.; Ramos, Kyle J.; Bolme, C. A.; ...

    2015-04-14

    Crystalline molecular explosives are key components of engineered explosive formulations. In precision applications a high degree of consistency and predictability is desired under a range of conditions to a variety of stimuli. Prediction of behaviors from mechanical response and failure to detonation initiation and detonation performance of the material is linked to accurate knowledge of the material structure and first stage of deformation: elasticity. The elastic response of pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RDX), and cyclotetramethylene tetranitramine (HMX), including aspects of material and measurement variability, and computational methods are described in detail. Experimental determinations of elastic tensors are compared, andmore » an evaluation of sources of error is presented. Furthermore, computed elastic constants are also compared for these materials and for triaminotrinitrobenzene (TATB), for which there are no measurements.« less

  13. Elasticity of crystalline molecular explosives

    SciTech Connect

    Hooks, Daniel E.; Ramos, Kyle J.; Bolme, C. A.; Cawkwell, Marc J.

    2015-04-14

    Crystalline molecular explosives are key components of engineered explosive formulations. In precision applications a high degree of consistency and predictability is desired under a range of conditions to a variety of stimuli. Prediction of behaviors from mechanical response and failure to detonation initiation and detonation performance of the material is linked to accurate knowledge of the material structure and first stage of deformation: elasticity. The elastic response of pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RDX), and cyclotetramethylene tetranitramine (HMX), including aspects of material and measurement variability, and computational methods are described in detail. Experimental determinations of elastic tensors are compared, and an evaluation of sources of error is presented. Furthermore, computed elastic constants are also compared for these materials and for triaminotrinitrobenzene (TATB), for which there are no measurements.

  14. Elastic waves in quasiperiodic structures

    NASA Astrophysics Data System (ADS)

    Velasco, V. R.; Zárate, J. E.

    2001-08-01

    We study the transverse and sagittal elastic waves in different quasiperiodic structures by means of the full transfer-matrix technique and surface Green-function matching method. The quasiperiodic structures follow Fibonacci, Thue-Morse and Rudin-Shapiro sequences, respectively. We consider finite structures having stress-free bounding surfaces and different generation orders, including up to more than 1000 interfaces. We obtain the dispersion relations for elastic waves and spatial localization of the different modes. The fragmentation of the spectrum for different sequences is evident for intermediate generation orders, in the case of transverse elastic waves, whereas, for sagittal elastic waves, higher generation orders are needed to show clearly the spectrum fragmentation. The results of Fibonacci and Thue-Morse sequences exhibit similarities not present in the results of Rudin-Shapiro sequences.

  15. Hilbert complexes of nonlinear elasticity

    NASA Astrophysics Data System (ADS)

    Angoshtari, Arzhang; Yavari, Arash

    2016-12-01

    We introduce some Hilbert complexes involving second-order tensors on flat compact manifolds with boundary that describe the kinematics and the kinetics of motion in nonlinear elasticity. We then use the general framework of Hilbert complexes to write Hodge-type and Helmholtz-type orthogonal decompositions for second-order tensors. As some applications of these decompositions in nonlinear elasticity, we study the strain compatibility equations of linear and nonlinear elasticity in the presence of Dirichlet boundary conditions and the existence of stress functions on non-contractible bodies. As an application of these Hilbert complexes in computational mechanics, we briefly discuss the derivation of a new class of mixed finite element methods for nonlinear elasticity.

  16. Elastic Properties of Mantle Minerals

    NASA Astrophysics Data System (ADS)

    Duffy, T. S.; Stan, C. V.

    2012-12-01

    The most direct information about the interior structure of the Earth comes from seismic wave velocities. Interpretation of seismic data requires an understanding of how sound velocities and elastic properties of minerals vary with pressure, temperature, crystal structure, and composition as well as the role of anelasticity, melts, etc. More generally, elastic moduli are important for understanding many solid-state phenomena including mechanical stability, interatomic interactions, material strength, compressibility, and phase transition mechanisms. The database of mineral elasticity measurements has been growing rapidly in recent years. In this work, we report initial results of an ongoing survey of our current knowledge of mineral elasticity at both ambient conditions and high pressures and temperatures. The analysis is selective, emphasizing single crystal measurements but also incorporating polycrystalline measurements and volume compression data as appropriate. The goal is to synthesize our current understanding of mineral elasticity in terms of structure and composition, and to identify the major remaining needs for experimental and theoretical work. Clinopyroxenes (Cpx) provide an example of our approach. A wide range of clinopyroxene compositions are found geologically and Mg-, Ca-, and Na-rich clinopyroxenes are expected to be important components in the upper mantle. The single-crystal elastic properties of a number of endmember Cpx compositions have been measured and these exhibit a range of ~25% in shear velocity. Those with monovalent cations (spodumene, jadeite) in the M2 site exhibit the highest velocities while Fe-rich (hendenbergit, acmite) compositions have the lowest velocities. The effects on velocity due to a wide range of chemical substitutions can be defined, but there are important discrepancies and omissions in the database. New measurements of omphacites, intermediate diopside-hedenbergite compositions, aegerine/acmite, augite, etc. are

  17. An analysis of short haul air passenger demand, volume 2

    NASA Technical Reports Server (NTRS)

    Blumer, T. P.; Swan, W. M.

    1978-01-01

    Several demand models for short haul air travel are proposed and calibrated on pooled data. The models are designed to predict demand and analyze some of the motivating phenomena behind demand generation. In particular, an attempt is made to include the effects of competing modes and of alternate destinations. The results support three conclusions: (1) the auto mode is the air mode's major competitor; (2) trip time is an overriding factor in intermodal competition, with air fare at its present level appearing unimportant to the typical short haul air traveler; and (3) distance appears to underly several demand generating phenomena, and therefore, must be considered very carefully to any intercity demand model. It may be the cause of the wide range of fare elasticities reported by researchers over the past 15 years. A behavioral demand model is proposed and calibrated. It combines the travel generating effects of income and population, the effects of modal split, the sensitivity of travel to price and time, and the effect of alternative destinations satisfying the trip purpose.

  18. An integrated communications demand model

    NASA Astrophysics Data System (ADS)

    Doubleday, C. F.

    1980-11-01

    A computer model of communications demand is being developed to permit dynamic simulations of the long-term evolution of demand for communications media in the U.K. to be made under alternative assumptions about social, economic and technological trends in British Telecom's business environment. The context and objectives of the project and the potential uses of the model are reviewed, and four key concepts in the demand for communications media, around which the model is being structured are discussed: (1) the generation of communications demand; (2) substitution between media; (3) technological convergence; and (4) competition. Two outline perspectives on the model itself are given.

  19. Demand Forecasting and Revenue Requirements, with Implications for Consideration in British Columbia,

    DTIC Science & Technology

    1983-05-01

    Econometric Study of Electricity Demand by Manufacturing Industries," NUREG /CR-11358, Oak Ridge, Tennessee: Energy Division, Oak Ridge National...Load for States and Utility Service Areas," NUREG /CR-2692, ORNL/TM- 7947, Oak Ridge, Tennessee: Energy Division, Oak Ridge National Laboratory, May...1982. Just, Richard E. and Chang, Hui S., "A Varying Elasticity Model of Electricity Demand with Given Appliance Saturation," NUREG /CR- 1956, ORNL/ NUREG

  20. Demand Activated Manufacturing Architecture

    SciTech Connect

    Bender, T.R.; Zimmerman, J.J.

    2001-02-07

    Honeywell Federal Manufacturing & Technologies (FM&T) engineers John Zimmerman and Tom Bender directed separate projects within this CRADA. This Project Accomplishments Summary contains their reports independently. Zimmerman: In 1998 Honeywell FM&T partnered with the Demand Activated Manufacturing Architecture (DAMA) Cooperative Business Management Program to pilot the Supply Chain Integration Planning Prototype (SCIP). At the time, FM&T was developing an enterprise-wide supply chain management prototype called the Integrated Programmatic Scheduling System (IPSS) to improve the DOE's Nuclear Weapons Complex (NWC) supply chain. In the CRADA partnership, FM&T provided the IPSS technical and business infrastructure as a test bed for SCIP technology, and this would provide FM&T the opportunity to evaluate SCIP as the central schedule engine and decision support tool for IPSS. FM&T agreed to do the bulk of the work for piloting SCIP. In support of that aim, DAMA needed specific DOE Defense Programs opportunities to prove the value of its supply chain architecture and tools. In this partnership, FM&T teamed with Sandia National Labs (SNL), Division 6534, the other DAMA partner and developer of SCIP. FM&T tested SCIP in 1998 and 1999. Testing ended in 1999 when DAMA CRADA funding for FM&T ceased. Before entering the partnership, FM&T discovered that the DAMA SCIP technology had an array of applications in strategic, tactical, and operational planning and scheduling. At the time, FM&T planned to improve its supply chain performance by modernizing the NWC-wide planning and scheduling business processes and tools. The modernization took the form of a distributed client-server planning and scheduling system (IPSS) for planners and schedulers to use throughout the NWC on desktops through an off-the-shelf WEB browser. The planning and scheduling process within the NWC then, and today, is a labor-intensive paper-based method that plans and schedules more than 8,000 shipped parts

  1. Elastic wavefield migration and tomography

    NASA Astrophysics Data System (ADS)

    Duan, Yuting

    Wavefield migration and tomography are well-developed under the acoustic assumption; however, multicomponent recorded seismic data include shear waves (S-modes) in addition to the compressional waves (P-modes). Constructing multicomponent wavefields and considering multiparameter model properties make it possible to utilize information provided by various wave modes, and this information allows for better characterization of the subsurface. In my thesis, I apply popular wavefield imaging and tomography to elastic media, and propose methods to address challenges posed by elastic multicomponent wavefields and multiparameter models. The key novelty of my research consists of new elastic imaging conditions, which generate elastic images with improved qualities and clear physical meaning. Moreover, I demonstrate an elastic wavefield tomography method to obtain realistic elastic models which benefits elastic migration. Migration techniques, including conventional RTM, extended RTM, and least-squares RTM (LSRTM), provide images of subsurface structures. I propose one imaging condition that computes potential images (PP, PS, SP, and SS). This imaging condition exploits pure P- and S-modes obtained by Helmholtz decomposition and corrects for the polarity reversal in PS and SP images. Using this imaging condition, I propose methods for conventional RTM and extended RTM. The extended imaging condition makes it possible to compute angle gathers for converted waves. The amplitudes of the scalar images indicate reflectivities, which can be used for amplitude verse offset (AVO) analysis; however, this imaging condition requires knowledge of the geologic dip. I propose a second imaging condition that computes perturbation images, i.e., P and S velocity perturbations. Because these images correspond to perturbations to material properties that are angle-independent, they do not have polarity reversals; therefore, they do not need dip information for polarity correction. I use this

  2. CAREER GUIDE FOR DEMAND OCCUPATIONS.

    ERIC Educational Resources Information Center

    LEE, E.R.; WELCH, JOHN L.

    THIS PUBLICATION UPDATES THE "CAREER GUIDE FOR DEMAND OCCUPATIONS" PUBLISHED IN 1959 AND PROVIDES COUNSELORS WITH INFORMATION ABOUT OCCUPATIONS IN DEMAND IN MANY AREAS WHICH REQUIRE PREEMPLOYMENT TRAINING. IT PRESENTS, IN COLUMN FORM, THE EDUCATION AND OTHER TRAINING USUALLY REQUIRED BY EMPLOYERS, HIGH SCHOOL SUBJECTS OF PARTICULAR PERTINENCE TO…

  3. Harnessing the power of demand

    SciTech Connect

    Sheffrin, Anjali; Yoshimura, Henry; LaPlante, David; Neenan, Bernard

    2008-03-15

    Demand response can provide a series of economic services to the market and also provide ''insurance value'' under low-likelihood, but high-impact circumstances in which grid reliablity is enhanced. Here is how ISOs and RTOs are fostering demand response within wholesale electricity markets. (author)

  4. Automated Demand Response and Commissioning

    SciTech Connect

    Piette, Mary Ann; Watson, David S.; Motegi, Naoya; Bourassa, Norman

    2005-04-01

    This paper describes the results from the second season of research to develop and evaluate the performance of new Automated Demand Response (Auto-DR) hardware and software technology in large facilities. Demand Response (DR) is a set of activities to reduce or shift electricity use to improve the electric grid reliability and manage electricity costs. Fully-Automated Demand Response does not involve human intervention, but is initiated at a home, building, or facility through receipt of an external communications signal. We refer to this as Auto-DR. The evaluation of the control and communications must be properly configured and pass through a set of test stages: Readiness, Approval, Price Client/Price Server Communication, Internet Gateway/Internet Relay Communication, Control of Equipment, and DR Shed Effectiveness. New commissioning tests are needed for such systems to improve connecting demand responsive building systems to the electric grid demand response systems.

  5. Demand Response for Ancillary Services

    SciTech Connect

    Alkadi, Nasr E; Starke, Michael R

    2013-01-01

    Many demand response resources are technically capable of providing ancillary services. In some cases, they can provide superior response to generators, as the curtailment of load is typically much faster than ramping thermal and hydropower plants. Analysis and quantification of demand response resources providing ancillary services is necessary to understand the resources economic value and impact on the power system. Methodologies used to study grid integration of variable generation can be adapted to the study of demand response. In the present work, we describe and illustrate a methodology to construct detailed temporal and spatial representations of the demand response resource and to examine how to incorporate those resources into power system models. In addition, the paper outlines ways to evaluate barriers to implementation. We demonstrate how the combination of these three analyses can be used to translate the technical potential for demand response providing ancillary services into a realizable potential.

  6. Supply and demand for wood as a source of energy in Zambia: An econometric analysis

    SciTech Connect

    Mupimpila, C.

    1993-01-01

    This study examines the status of biomass energy in Zambia. In its current usage, the concept of biomass energy often implies woodfuel because woodfuel is the main biomass energy. This study develops an econometric model of household woodfuel demand and also evaluates the supply of woodfuel in Zambia. The study finds that there are significant sectoral differences in woodfuel demand between the rural and urban sectors. In the rural sector, inflation is by far the most significant determinant of household woodfuel demand. The coefficients on inflation are statistically significant at better than the one percent level and also have expected positive signs. In the urban sector, inflation is again by far the most significant determinant of woodfuel demand. However, in the urban sector, household income and woodfuel price are also significant determinants of demand. The coefficients on inflation, household income, and woodfuel price are all significant at better than the one percent level and have expected signs. The income elasticity of woodfuel demand is positive, suggesting that in the short-run, woodfuel is a normal good. However, the elasticity of woodfuel demand with respect to growth in investment is negative, indicating that long-run structural change in the economy reduces woodfuel demand.

  7. Photoacoustic elastic oscillation and characterization.

    PubMed

    Gao, Fei; Feng, Xiaohua; Zheng, Yuanjin

    2015-08-10

    Photoacoustic imaging and sensing have been studied extensively to probe the optical absorption of biological tissue in multiple scales ranging from large organs to small molecules. However, its elastic oscillation characterization is rarely studied and has been an untapped area to be explored. In literature, photoacoustic signal induced by pulsed laser is commonly modelled as a bipolar "N-shape" pulse from an optical absorber. In this paper, the photoacoustic damped oscillation is predicted and modelled by an equivalent mass-spring system by treating the optical absorber as an elastic oscillator. The photoacoustic simulation incorporating the proposed oscillation model shows better agreement with the measured signal from an elastic phantom, than conventional photoacoustic simulation model. More interestingly, the photoacoustic damping oscillation effect could potentially be a useful characterization approach to evaluate biological tissue's mechanical properties in terms of relaxation time, peak number and ratio beyond optical absorption only, which is experimentally demonstrated in this paper.

  8. Nonresident Enrollment Demand in Public Higher Education: An Analysis at National, State, and Institutional Levels

    ERIC Educational Resources Information Center

    Zhang, Liang

    2007-01-01

    This article estimates the standard demand equations for nonresident students using national, state, and institutional level data. The national-level analysis reveals a near-unitary price elasticity, but increases in nonresident tuition and fees do not decrease nonresident enrollment. Finally, results from the institutional level of analysis…

  9. Demand for Primary Schooling in Rural Mali: Should User Fees Be Increased?

    ERIC Educational Resources Information Center

    Birdsall, Nancy; Orivel, Francois

    1996-01-01

    Assesses the effect of school fees on primary school attendance, using household and school survey data from rural Mali. Estimates elasticity of demand regarding fees and compares it with effects of distance and quality on enrollment. User fees can provide a partial solution to the quality/enrollment problem, but cannot solve the distance problem.…

  10. An analysis of at-home demand for ice cream in the United States.

    PubMed

    Davis, C G; Blayney, D P; Yen, S T; Cooper, J

    2009-12-01

    Ice cream has been manufactured commercially in the United States since the middle of the 19th century. Ice cream and frozen dessert products comprise an important and relatively stable component of the United States dairy industry. As with many other dairy products, ice cream is differentiated in several dimensions. A censored translog demand system model was employed to analyze purchases of 3 ice cream product categories. The objective of this study was to determine the effect that changes in retail prices and consumer income have on at-home ice cream consumption. The analysis was based on Nielsen 2005 home scan retail data and used marital status, age, race, education, female employment status, and location in the estimations of aggregate demand elasticities. Results revealed that price and consumer income were the main determinants of demand for ice cream products. Calculated own-price elasticities indicated relatively elastic responses by consumers for all categories except for compensated bulk ice cream. All expenditure elasticities were inelastic except for bulk ice cream, and most of the ice cream categories were substitutes. Ongoing efforts to examine consumer demand for these products will assist milk producers, dairy processors and manufacturers, and dairy marketers as they face changing consumer responses to food and diet issues.

  11. Cellular Uptake of Elastic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Yi, Xin; Shi, Xinghua; Gao, Huajian

    2011-08-01

    A fundamental understanding of cell-nanomaterial interaction is of essential importance to nanomedicine and safe applications of nanotechnology. Here we investigate the adhesive wrapping of a soft elastic vesicle by a lipid membrane. We show that there exist a maximum of five distinct wrapping phases based on the stability of full wrapping, partial wrapping, and no wrapping states. The wrapping phases depend on the vesicle size, adhesion energy, surface tension of membrane, and bending rigidity ratio between vesicle and membrane. These results are of immediate interest to the study of vesicular transport and endocytosis or phagocytosis of elastic particles into cells.

  12. Shape memory polymer network with thermally distinct elasticity and plasticity

    PubMed Central

    Zhao, Qian; Zou, Weike; Luo, Yingwu; Xie, Tao

    2016-01-01

    Stimuli-responsive materials with sophisticated yet controllable shape-changing behaviors are highly desirable for real-world device applications. Among various shape-changing materials, the elastic nature of shape memory polymers allows fixation of temporary shapes that can recover on demand, whereas polymers with exchangeable bonds can undergo permanent shape change via plasticity. We integrate the elasticity and plasticity into a single polymer network. Rational molecular design allows these two opposite behaviors to be realized at different temperature ranges without any overlap. By exploring the cumulative nature of the plasticity, we demonstrate easy manipulation of highly complex shapes that is otherwise extremely challenging. The dynamic shape-changing behavior paves a new way for fabricating geometrically complex multifunctional devices. PMID:26824077

  13. Cheaper by the Dozen: Using Sibling Discounts at Catholic Schools to Estimate the Price Elasticity of Private School Attendance. NBER Working Paper No. 15461

    ERIC Educational Resources Information Center

    Dynarski, Susan; Gruber, Jonathan; Li, Danielle

    2009-01-01

    The effect of vouchers on sorting between private and public schools depends upon the price elasticity of demand for private schooling. Estimating this elasticity is empirically challenging because prices and quantities are jointly determined in the market for private schooling. We exploit a unique and previously undocumented source of variation…

  14. Modeling the Demand for Cocaine

    DTIC Science & Technology

    1994-01-01

    the Demand for Cocaine Susan S. Everingham C. Peter Rydell Pre~redfor the Office of NatinalDrug Control Policy United States Army DRUG POLICY...Demand for Cocaine . 60 50- sm 40- squared 30- delta prevalence 20- 10- 0.2 0 0.15 0.15 󈧄 b C; 0 i Sum squared delta 0.2 prevalence 0.195 EQ 50-50 0,19...model of the demand for cocaine that was fit to 20 years of data on the current cocaine epidemic in the United States. It also describes the analysis

  15. [Use of elastic compression stockings].

    PubMed

    Kallestrup, Lisbeth; Søgaard, Tine; Schjødt, Inge; Grove, Erik Lerkevang

    2014-08-04

    Post-thrombotic syndrome (PTS) is caused by venous insufficiency and is a frequent complication of deep venous thrombosis. Patients with PTS have reduced quality of life and an increased risk of recurrent deep venous thrombosis. Importantly, the risk of PTS is halved by the use of elastic compression stockings. This review outlines important practical aspects related to correct clinical use of these stockings.

  16. HEMP. Hydrodynamic Elastic Magneto Plastic

    SciTech Connect

    Wilkins, M.L.; Levatin, J.A.

    1985-02-01

    The HEMP code solves the conservation equations of two-dimensional elastic-plastic flow, in plane x-y coordinates or in cylindrical symmetry around the x-axis. Provisions for calculation of fixed boundaries, free surfaces, pistons, and boundary slide planes have been included, along with other special conditions.

  17. Duration of an Elastic Collision

    ERIC Educational Resources Information Center

    de Izarra, Charles

    2012-01-01

    With a pedagogical goal, this paper deals with a study of the duration of an elastic collision of an inflatable spherical ball on a planar surface suitable for undergraduate studies. First, the force generated by the deformed spherical ball is obtained under assumptions that are discussed. The study of the motion of the spherical ball colliding…

  18. Robustness Elasticity in Complex Networks

    PubMed Central

    Matisziw, Timothy C.; Grubesic, Tony H.; Guo, Junyu

    2012-01-01

    Network robustness refers to a network’s resilience to stress or damage. Given that most networks are inherently dynamic, with changing topology, loads, and operational states, their robustness is also likely subject to change. However, in most analyses of network structure, it is assumed that interaction among nodes has no effect on robustness. To investigate the hypothesis that network robustness is not sensitive or elastic to the level of interaction (or flow) among network nodes, this paper explores the impacts of network disruption, namely arc deletion, over a temporal sequence of observed nodal interactions for a large Internet backbone system. In particular, a mathematical programming approach is used to identify exact bounds on robustness to arc deletion for each epoch of nodal interaction. Elasticity of the identified bounds relative to the magnitude of arc deletion is assessed. Results indicate that system robustness can be highly elastic to spatial and temporal variations in nodal interactions within complex systems. Further, the presence of this elasticity provides evidence that a failure to account for nodal interaction can confound characterizations of complex networked systems. PMID:22808060

  19. Saving Electricity and Demand Response

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Nobuyuki

    A lot of people lost their lives in the tremendous earthquake in Tohoku region on March 11. A large capacity of electric power plants in TEPCO area was also damaged and large scale power shortage in this summer is predicted. In this situation, electricity customers are making great effort to save electricity to avoid planned outage. Customers take actions not only by their selves but also by some customers' cooperative movements. All actions taken actually are based on responses to request form the government or voluntary decision. On the other hand, demand response based on a financial stimulus is not observed as an actual behavior. Saving electricity by this demand response only discussed in the newspapers. In this commentary, the events regarding electricity-saving measure after this disaster are described and the discussions on demand response, especially a raise in power rate, are put into shapes in the context of this electricity supply-demand gap.

  20. Speech measures indicating workload demand.

    PubMed

    Brenner, M; Doherty, E T; Shipp, T

    1994-01-01

    Heart rate and six speech measures were evaluated using a manual tracking task under different workload demands. Following training, 17 male subjects performed three task trials: a difficult trial, with a $50 incentive for successful performance at a very demanding level; an easy trial, with a $2 incentive for successful performance at a simple level; and a baseline trial, in which there was physiological monitoring but no tracking performance. Subjects counted aloud during the trials. It was found that heart rate, speaking fundamental frequency (pitch), and vocal intensity (loudness) increased significantly with workload demands. Speaking rate showed a marginal increase, while vocal jitter and vocal shimmer did not show reliable changes. A derived speech measure, which statistically combined information from all other speech measures except shimmer, was also evaluated. It increased significantly with workload demands and was surprisingly robust in showing differences for individual subjects. It appears that speech analysis can provide practical workload information.

  1. Industrial Demand Module - NEMS Documentation

    EIA Publications

    2014-01-01

    Documents the objectives, analytical approach, and development of the National Energy Modeling System (NEMS) Industrial Demand Module. The report catalogues and describes model assumptions, computational methodology, parameter estimation techniques, and model source code.

  2. Residential Demand Module - NEMS Documentation

    EIA Publications

    2014-01-01

    Model Documentation - Documents the objectives, analytical approach, and development of the National Energy Modeling System (NEMS) Residential Sector Demand Module. The report catalogues and describes the model assumptions, computational methodology, parameter estimation techniques, and FORTRAN source code.

  3. Demand Response Spinning Reserve Demonstration

    SciTech Connect

    Eto, Joseph H.; Nelson-Hoffman, Janine; Torres, Carlos; Hirth,Scott; Yinger, Bob; Kueck, John; Kirby, Brendan; Bernier, Clark; Wright,Roger; Barat, A.; Watson, David S.

    2007-05-01

    The Demand Response Spinning Reserve project is a pioneeringdemonstration of how existing utility load-management assets can providean important electricity system reliability resource known as spinningreserve. Using aggregated demand-side resources to provide spinningreserve will give grid operators at the California Independent SystemOperator (CAISO) and Southern California Edison (SCE) a powerful, newtool to improve system reliability, prevent rolling blackouts, and lowersystem operating costs.

  4. Residential water demand with endogenous pricing: The Canadian Case

    NASA Astrophysics Data System (ADS)

    Reynaud, Arnaud; Renzetti, Steven; Villeneuve, Michel

    2005-11-01

    In this paper, we show that the rate structure endogeneity may result in a misspecification of the residential water demand function. We propose to solve this endogeneity problem by estimating a probabilistic model describing how water rates are chosen by local communities. This model is estimated on a sample of Canadian local communities. We first show that the pricing structure choice reflects efficiency considerations, equity concerns, and, in some cases, a strategy of price discrimination across consumers by Canadian communities. Hence estimating the residential water demand without taking into account the pricing structures' endogeneity leads to a biased estimation of price and income elasticities. We also demonstrate that the pricing structure per se plays a significant role in influencing price responsiveness of Canadian residential consumers.

  5. Price elasticity estimates for tobacco products in India.

    PubMed

    John, Rijo M

    2008-05-01

    The tax base of tobacco in India is heavily dependent on about 14% of tobacco users, who smoke cigarettes. Non-cigarette tobacco products accounting for 85% of the tobacco consumption contributes only 15% of the total tobacco taxes. Though taxation is an important tool to regulate consumption of tobacco, there have been no estimates of price elasticities for different tobacco products in India to date, which can guide tax policy on tobacco. This paper, for the first time in India, examines the price elasticity of demand for bidis, cigarettes and leaf tobacco at the national level using a representative cross-section of households. This study found that own-price elasticity estimates of different tobacco products in India ranged between -0.4 to -0.9, with bidis (an indigenous hand-rolled smoked tobacco preparation in India) and leaf tobacco having elasticities close to unity. Cigarettes were the least price elastic of all. With some assumptions, it is shown that the tax on bidis can be increased to Rs. 100 per 1000 sticks compared with the current Rs. 14 and the tax on an average cigarette can be increased to Rs. 3.5 per stick without any fear of losing revenue. The paper argues that the current system of taxing cigarettes in India based on the presence of filters and the length of cigarettes has no justification on health grounds, and should be abolished, if reducing tobacco consumption and the consequent disease burden is one of the objectives of tobacco taxation policy. It also argues that attempts to regulate tobacco use without effecting significant tax increases on bidis may not produce desired results.

  6. Is the demand for alcoholic beverages in developing countries sensitive to price? Evidence from China.

    PubMed

    Tian, Guoqiang; Liu, Feng

    2011-06-01

    Economic literature in developed countries suggests that demand for alcoholic beverages is sensitive to price, with an estimated price elasticity ranging from -0.38 for beer and -0.7 for liquor. However, few studies have been conducted in developing countries. We employ a large individual-level dataset in China to estimate the effects of price on alcohol demand. Using the data from China Health and Nutrition Survey for the years 1993, 1997, 2000, 2004 and 2006, we estimate two-part models of alcohol demand. Results show the price elasticity is virtually zero for beer and only -0.12 for liquor, which is far smaller than those derived from developed countries. Separate regressions by gender reveals the results are mainly driven by men. The central implication of this study is, while alcohol tax increases can raise government revenue, it alone is not an effective policy to reduce alcohol related problems in China.

  7. On the anisotropic elastic properties of hydroxyapatite.

    NASA Technical Reports Server (NTRS)

    Katz, J. L.; Ukraincik, K.

    1971-01-01

    Experimental measurements of the isotropic elastic moduli on polycrystalline specimens of hydroxyapatite and fluorapatite are compared with elastic constants measured directly from single crystals of fluorapatite in order to derive a set of pseudo single crystal elastic constants for hydroxyapatite. The stiffness coefficients thus derived are given. The anisotropic and isotropic elastic properties are then computed and compared with similar properties derived from experimental observations of the anisotropic behavior of bone.

  8. Probabilistic seismic demand analysis using advanced ground motion intensity measures

    USGS Publications Warehouse

    Tothong, P.; Luco, N.

    2007-01-01

    One of the objectives in performance-based earthquake engineering is to quantify the seismic reliability of a structure at a site. For that purpose, probabilistic seismic demand analysis (PSDA) is used as a tool to estimate the mean annual frequency of exceeding a specified value of a structural demand parameter (e.g. interstorey drift). This paper compares and contrasts the use, in PSDA, of certain advanced scalar versus vector and conventional scalar ground motion intensity measures (IMs). One of the benefits of using a well-chosen IM is that more accurate evaluations of seismic performance are achieved without the need to perform detailed ground motion record selection for the nonlinear dynamic structural analyses involved in PSDA (e.g. record selection with respect to seismic parameters such as earthquake magnitude, source-to-site distance, and ground motion epsilon). For structural demands that are dominated by a first mode of vibration, using inelastic spectral displacement (Sdi) can be advantageous relative to the conventionally used elastic spectral acceleration (Sa) and the vector IM consisting of Sa and epsilon (??). This paper demonstrates that this is true for ordinary and for near-source pulse-like earthquake records. The latter ground motions cannot be adequately characterized by either Sa alone or the vector of Sa and ??. For structural demands with significant higher-mode contributions (under either of the two types of ground motions), even Sdi (alone) is not sufficient, so an advanced scalar IM that additionally incorporates higher modes is used.

  9. Chicago's water market: Dynamics of demand, prices and scarcity rents

    USGS Publications Warehouse

    Ipe, V.C.; Bhagwat, S.B.

    2002-01-01

    Chicago and its suburbs are experiencing an increasing demand for water from a growing population and economy and may experience water scarcity in the near future. The Chicago metropolitan area has nearly depleted its groundwater resources to a point where interstate conflicts with Wisconsin could accompany an increased reliance on those sources. Further, the withdrawals from Lake Michigan is limited by the Supreme Court decree. The growing demand and indications of possible scarcity suggest a need to reexamine the pricing policies and the dynamics of demand. The study analyses the demand for water and develops estimates of scarcity rents for water in Chicago. The price and income elasticities computed at the means are -0.002 and 0.0002 respectively. The estimated scarcity rents ranges from $0.98 to $1.17 per thousand gallons. The results indicate that the current prices do not fully account for the scarcity rents and suggest a current rate with in the range $1.53 to $1.72 per thousand gallons.

  10. Oil Price Uncertainty, Transport Fuel Demand and Public Health

    PubMed Central

    He, Ling-Yun; Yang, Sheng; Chang, Dongfeng

    2017-01-01

    Based on the panel data of 306 cities in China from 2002 to 2012, this paper investigates China’s road transport fuel (i.e., gasoline and diesel) demand system by using the Almost Ideal Demand System (AIDS) and the Quadratic AIDS (QUAIDS) models. The results indicate that own-price elasticities for different vehicle categories range from −1.215 to −0.459 (by AIDS) and from −1.399 to −0.369 (by QUAIDS). Then, this study estimates the air pollution emissions (CO, NOx and PM2.5) and public health damages from the road transport sector under different oil price shocks. Compared to the base year 2012, results show that a fuel price rise of 30% can avoid 1,147,270 tonnes of pollution emissions; besides, premature deaths and economic losses decrease by 16,149 cases and 13,817.953 million RMB yuan respectively; while based on the non-linear health effect model, the premature deaths and total economic losses decrease by 15,534 and 13,291.4 million RMB yuan respectively. Our study combines the fuel demand and health evaluation models and is the first attempt to address how oil price changes influence public health through the fuel demand system in China. Given its serious air pollution emission and substantial health damages, this paper provides important insights for policy makers in terms of persistent increasing in fuel consumption and the associated health and economic losses. PMID:28257076

  11. Insatiable demands: Income, energy and environmental policy in Madagascar

    SciTech Connect

    Shaw, C.L.

    1993-01-01

    The island nation of Madagascar is suffering the collision of three distinct trends: economic stagnation, a rapidly expanding population and a severely threatened natural resource base. Demands for growth, new energy reserves and environmental conservation, especially of forest resources, are creating a policy dilemma for both government officials and donors. This study seeks to bring new evidence to bear on this policy dilemma. Primary data on urban household income, family size and consumption of various energy types are used to test two main hypothesis (1) that charcoal, which constitutes the fuel of choice for a vast majority of the sample, is a normal rather than an inferior good, and (2) that demand for wood-fuels constitutes a genuine threat to the viability of the forest resource. The data indicate that income elasticities of demand for charcoal are positive over a broad range of per capita income levels, revealing that charcoal is, indeed a normal good for a large portion of the population represented by the sample. A model of forest degradation is built which establishes a clear link between wood-fuel demand and forest degradation. Together, these findings make clear that under current income patterns, and for the forseeable future, charcoal is a normal good and its consumption by urban residents constitutes a serious threat to the natural forest resource. The study concludes with a policy analysis which identifies existing market failures due to government policies and recommends changes based on tested policy prescriptions in other parts of the developing world.

  12. Effects of price and availability on abortion demand.

    PubMed

    Gohmann, S F; Ohsfeldt, R L

    1993-10-01

    This study explained the variation in US state abortion demand due to the price of services, the net of insurance cost of birth services, the ability to pay, contraceptive use, individual attitudes regarding abortion, and government policy affecting cost of benefits of terminating an unintended pregnancy or of carrying to birth. The empirical model uses pooled data from 48 states for 1982, 1984, 1985, and 1987. Prices are deflated to 1977 dollars. Another two-staged least squares model is based on cross-sectional state level data for 1985. The dependent variable is the log of abortion per 1000 pregnancies. Other variables pertain to income, education, labor force, family planning, tax, aid to families with dependent children, religion, and abortion-related measures. The results of the cross-sectional analysis are consistent with Medoff's and Garbacz's findings. The estimated coefficient of per capita income is positive with a point elasticity ranging from 0.62 to 1.0. The model with the most complete specifications has an abortion price elasticity range from -0.75 to -1.3 and is statistically significant when religion measures are excluded. The Hausman test shows the pro-choice variable significantly correlated with the error term. The net price of birth services is not statistically significant. Catholic religion and no religion are only significant when the abortion provider variable is excluded. The suggestion is that the effect of Catholicism is ambiguous. In the pooled analysis, the fixed effects model is used to control for abortion attitudes and other unobserved factors. Abortion demand includes abortion per 1000 pregnancies, the ratio of abortions to pregnancies, and the logarithm of abortions per 1000 pregnancies. Higher income is associated with a higher abortion rate and elasticities of 0.76 and 0.35 and is associated with a higher pregnancy rate. The abortion ratio is found to be elastic with respect to price, and price elasticities are sensitive to

  13. Energy supply and demand in California

    NASA Technical Reports Server (NTRS)

    Griffith, E. D.

    1978-01-01

    The author expresses his views on future energy demand on the west coast of the United States and how that energy demand translates into demand for major fuels. He identifies the major uncertainties in determining what future demands may be. The major supply options that are available to meet projected demands and the policy implications that flow from these options are discussed.

  14. Respiratory-related limitations in physically demanding occupations.

    PubMed

    Brown, Peter I; McConnell, Alison K

    2012-04-01

    Respiratory muscle work limits high-intensity exercise tolerance in healthy human beings. Emerging evidence suggests similar limitations exist during submaximal work in some physically demanding occupations. In an occupational setting, heavy loads are routinely carried upon the trunk in the form of body armor, backpacks, and/or compressed air cylinders by military, emergency service, and mountain rescue personnel. This personal and respiratory protective equipment impairs respiratory muscle function and increases respiratory muscle work. More specifically, thoracic load carriage induces a restrictive ventilatory limitation which increases the elastic work of breathing, rendering the respiratory muscles vulnerable to fatigue and inducing a concomitant reduction in exercise tolerance. Similarly, breathing apparatus worn by occupational personnel, including fire fighters and military and commercial divers, increases the inspiratory elastic and expiratory resistive work of breathing, precipitating significant inspiratory and expiratory muscle fatigue and a reduction in exercise tolerance. An argument is presented that the unique respiratory challenges encountered in some occupational settings require further research, since these may affect the operational effectiveness and the health and safety of personnel working in physically demanding occupations.

  15. Elastic modulus of viral nanotubes

    NASA Astrophysics Data System (ADS)

    Zhao, Yue; Ge, Zhibin; Fang, Jiyu

    2008-09-01

    We report an experimental and theoretical study of the radial elasticity of tobacco mosaic virus (TMV) nanotubes. An atomic force microscope tip is used to apply small radial indentations to deform TMV nanotubes. The initial elastic response of TMV nanotubes can be described by finite-element analysis in 5nm indentation depths and Hertz theory in 1.5nm indentation depths. The derived radial Young’s modulus of TMV nanotubes is 0.92±0.15GPa from finite-element analysis and 1.0±0.2GPa from the Hertz model, which are comparable with the reported axial Young’s modulus of 1.1GPa [Falvo , Biophys. J. 72, 1396 (1997)].

  16. Structure and elasticity of glaucophane

    NASA Astrophysics Data System (ADS)

    Bezacier, L.; Mookherjee, M.

    2012-12-01

    We report equation of state and elasticity of glaucophane amphibole [Na2Mg3Al2Si8O22(OH)2] up to 9 GPa, which encompasses its experimentally observed stability field. The full elastic constant tensor reveals significantly larger stiffness along (100) plane. The [100] direction is relatively softer. This anisotropy is related to the stacking of the stiffer tetrahedral units along [010] and [001] directions within the crystal structure. Glaucophane is a dominant mineral constituent of blueschist facies rock, and has significantly lower velocities compared to garnet bearing eclogites. In addition, glaucophane is anisotropic and could account for the observed low velocity layer (LVL) in the subducting slabs at depth range within the thermodynamic stability of glaucophane.

  17. Elastic sealants for surgical applications.

    PubMed

    Annabi, Nasim; Yue, Kan; Tamayol, Ali; Khademhosseini, Ali

    2015-09-01

    Sealants have emerged as promising candidates for replacing sutures and staples to prevent air and liquid leakages during and after the surgeries. Their physical properties and adhesion strength to seal the wound area without limiting the tissue movement and function are key factors in their successful implementation in clinical practice. In this contribution, the advances in the development of elastic sealants formed from synthetic and natural materials are critically reviewed and their shortcomings are pointed out. In addition, we highlight the applications in which elasticity of the sealant is critical and outline the limitations of the currently available sealants. This review will provide insights for the development of novel bioadhesives with advanced functionality for surgical applications.

  18. Vibrations of elastically restrained frames

    NASA Astrophysics Data System (ADS)

    Albarracín, Carlos Marcelo; Grossi, Ricardo Oscar

    2005-07-01

    This paper deals with the determination of eigenfrequencies of a frame which consists of a beam supported by a column and is submitted to intermediate elastic constraints. The ends of the frame are elastically restrained against rotation and translation. The individual members of the frame are assumed to be governed by the transverse and axial vibration theory of an Euler-Bernoulli beam. The boundary and eigenvalue problem which governs the dynamical behavior of the frame structure is derived using the techniques of calculus of variations. Exact values of eigenfrequencies are determined by the application of the separation of variables method. Also, results are obtained by the use of the finite element method. The natural frequencies and mode shapes are presented for a wide range of values of the restraint parameters. Several particular cases are presented and some of these have been compared with those available in the literature.

  19. Elastic heterogeneity in metallic glasses.

    SciTech Connect

    Dmowski, , W.; Iwashita, T.; Chuang, C.-P.; Almer, J. D; Egami, T.; X-Ray Science Division; Univ. of Tennessee; ORNL

    2010-01-01

    When a stress is applied on a metallic glass it deforms following Hook's law. Therefore it may appear obvious that a metallic glass deforms elastically. Using x-ray diffraction and anisotropic pair-density function analysis we show that only about 3/4 in volume fraction of metallic glasses deforms elastically, whereas the rest of the volume is anelastic and in the experimental time scale deform without resistance. We suggest that this anelastic portion represents residual liquidity in the glassy state. Many theories, such as the free-volume theory, assume the density of defects in the glassy state to be of the order of 1%, but this result shows that it is as much as a quarter.

  20. Elastic Heterogeneity in Metallic Glasses

    NASA Astrophysics Data System (ADS)

    Dmowski, W.; Iwashita, T.; Chuang, C.-P.; Almer, J.; Egami, T.

    2010-11-01

    When a stress is applied on a metallic glass it deforms following Hook’s law. Therefore it may appear obvious that a metallic glass deforms elastically. Using x-ray diffraction and anisotropic pair-density function analysis we show that only about (3)/(4) in volume fraction of metallic glasses deforms elastically, whereas the rest of the volume is anelastic and in the experimental time scale deform without resistance. We suggest that this anelastic portion represents residual liquidity in the glassy state. Many theories, such as the free-volume theory, assume the density of defects in the glassy state to be of the order of 1%, but this result shows that it is as much as a quarter.

  1. Linear elastic fracture mechanics primer

    NASA Technical Reports Server (NTRS)

    Wilson, Christopher D.

    1992-01-01

    This primer is intended to remove the blackbox perception of fracture mechanics computer software by structural engineers. The fundamental concepts of linear elastic fracture mechanics are presented with emphasis on the practical application of fracture mechanics to real problems. Numerous rules of thumb are provided. Recommended texts for additional reading, and a discussion of the significance of fracture mechanics in structural design are given. Griffith's criterion for crack extension, Irwin's elastic stress field near the crack tip, and the influence of small-scale plasticity are discussed. Common stress intensities factor solutions and methods for determining them are included. Fracture toughness and subcritical crack growth are discussed. The application of fracture mechanics to damage tolerance and fracture control is discussed. Several example problems and a practice set of problems are given.

  2. Household demand for insecticide-treated bednets in Tanzania and policy options for increasing uptake.

    PubMed

    Gingrich, Chris D; Hanson, Kara G; Marchant, Tanya J; Mulligan, Jo-Ann; Mponda, Hadji

    2011-03-01

    There has been considerable controversy about the most appropriate means of delivering insecticide-treated nets (ITNs) to prevent malaria. Household demand for ITNs is a key factor influencing the choice of delivery strategy, but evidence to date about price and income elasticities comes either from studies of hypothetical willingness to pay or small-scale policy experiments. This study estimates the price and income elasticities of demand for ITNs using nationally representative household survey data and actual consumer choices, in the context of a national scheme to provide vouchers for subsidized nets to pregnant women in Tanzania. Under this distribution system, the estimated price elasticity of demand for subsidized ITNs equals -0.12 and the income elasticity estimates range from zero to 0.47, depending on household socio-economic status. The model also shows a substantial decline in short-term ITN purchases for women whose household received a free ITN. These findings suggest that if the Tanzanian government continues to use a mixed public-private model to distribute ITNs, increasing the consumer subsidy alone will not dramatically improve ITN coverage. A concerted effort is required including an increase in the subsidy amount, attention to income growth for poor households, increases in women's and girls' education levels, and expansion of the retail ITN distribution network. Use of a catch-up campaign to distribute free ITNs would increase coverage but raises questions about the effect of households' long-term purchase decisions for ITNs.

  3. Stability of elastically supported columns

    NASA Technical Reports Server (NTRS)

    Niles, Alfred S; Viscovich, Steven J

    1942-01-01

    A criterion is developed for the stiffness required of elastic lateral supports at the ends of a compression member to provide stability. A method based on this criterion is then developed for checking the stability of a continuous beam-column. A related method is also developed for checking the stability of a member of a pin-jointed truss against rotation in the plane of the truss.

  4. Fundamental Travel Demand Model Example

    NASA Technical Reports Server (NTRS)

    Hanssen, Joel

    2010-01-01

    Instances of transportation models are abundant and detailed "how to" instruction is available in the form of transportation software help documentation. The purpose of this paper is to look at the fundamental inputs required to build a transportation model by developing an example passenger travel demand model. The example model reduces the scale to a manageable size for the purpose of illustrating the data collection and analysis required before the first step of the model begins. This aspect of the model development would not reasonably be discussed in software help documentation (it is assumed the model developer comes prepared). Recommendations are derived from the example passenger travel demand model to suggest future work regarding the data collection and analysis required for a freight travel demand model.

  5. Turkey's energy demand and supply

    SciTech Connect

    Balat, M.

    2009-07-01

    The aim of the present article is to investigate Turkey's energy demand and the contribution of domestic energy sources to energy consumption. Turkey, the 17th largest economy in the world, is an emerging country with a buoyant economy challenged by a growing demand for energy. Turkey's energy consumption has grown and will continue to grow along with its economy. Turkey's energy consumption is high, but its domestic primary energy sources are oil and natural gas reserves and their production is low. Total primary energy production met about 27% of the total primary energy demand in 2005. Oil has the biggest share in total primary energy consumption. Lignite has the biggest share in Turkey's primary energy production at 45%. Domestic production should be to be nearly doubled by 2010, mainly in coal (lignite), which, at present, accounts for almost half of the total energy production. The hydropower should also increase two-fold over the same period.

  6. International Oil Supplies and Demands

    SciTech Connect

    Not Available

    1991-09-01

    The eleventh Energy Modeling Forum (EMF) working group met four times over the 1989--90 period to compare alternative perspectives on international oil supplies and demands through 2010 and to discuss how alternative supply and demand trends influence the world's dependence upon Middle Eastern oil. Proprietors of eleven economic models of the world oil market used their respective models to simulate a dozen scenarios using standardized assumptions. From its inception, the study was not designed to focus on the short-run impacts of disruptions on oil markets. Nor did the working group attempt to provide a forecast or just a single view of the likely future path for oil prices. The model results guided the group's thinking about many important longer-run market relationships and helped to identify differences of opinion about future oil supplies, demands, and dependence.

  7. International Oil Supplies and Demands

    SciTech Connect

    Not Available

    1992-04-01

    The eleventh Energy Modeling Forum (EMF) working group met four times over the 1989--1990 period to compare alternative perspectives on international oil supplies and demands through 2010 and to discuss how alternative supply and demand trends influence the world's dependence upon Middle Eastern oil. Proprietors of eleven economic models of the world oil market used their respective models to simulate a dozen scenarios using standardized assumptions. From its inception, the study was not designed to focus on the short-run impacts of disruptions on oil markets. Nor did the working group attempt to provide a forecast or just a single view of the likely future path for oil prices. The model results guided the group's thinking about many important longer-run market relationships and helped to identify differences of opinion about future oil supplies, demands, and dependence.

  8. Improved Indentation Test for Measuring Nonlinear Elasticity

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.

    2004-01-01

    A cylindrical-punch indentation technique has been developed as a means of measuring the nonlinear elastic responses of materials -- more specifically, for measuring the moduli of elasticity of materials in cases in which these moduli vary with applied loads. This technique offers no advantage for characterizing materials that exhibit purely linear elastic responses (constant moduli of elasticity, independent of applied loads). However, the technique offers a significant advantage for characterizing such important materials as plasma-sprayed thermal-barrier coatings, which, in cyclic loading, exhibit nonlinear elasticity with hysteresis related to compaction and sliding within their microstructures.

  9. Teaching nonlinear dynamics through elastic cords

    NASA Astrophysics Data System (ADS)

    Chacón, R.; Galán, C. A.; Sánchez-Bajo, F.

    2011-01-01

    We experimentally studied the restoring force of a length of stretched elastic cord. A simple analytical expression for the restoring force was found to fit all the experimental results for different elastic materials. Remarkably, this analytical expression depends upon an elastic-cord characteristic parameter which exhibits two limiting values corresponding to two nonlinear springs with different Hooke's elastic constants. Additionally, the simplest model of elastic cord dynamics is capable of exhibiting a great diversity of nonlinear phenomena, including bifurcations and chaos, thus providing a suitable alternative model system for discussing the basic essentials of nonlinear dynamics in the context of intermediate physics courses at university level.

  10. Phase diagram of elastic spheres.

    PubMed

    Athanasopoulou, L; Ziherl, P

    2017-02-15

    Experiments show that polymeric nanoparticles often self-assemble into several non-close-packed lattices in addition to the face-centered cubic lattice. Here, we explore theoretically the possibility that the observed phase sequences may be associated with the softness of the particles, which are modeled as elastic spheres interacting upon contact. The spheres are described by two finite-deformation theories of elasticity, the modified Saint-Venant-Kirchhoff model and the neo-Hookean model. We determine the range of indentations where the repulsion between the spheres is pairwise additive and agrees with the Hertz theory. By computing the elastic energies of nine trial crystal lattices at densities far beyond the Hertzian range, we construct the phase diagram and find the face- and body-centered cubic lattices as well as the A15 lattice and the simple hexagonal lattice, with the last two being stable at large densities where the spheres are completely faceted. These results are qualitatively consistent with observations, suggesting that deformability may indeed be viewed as a generic property that determines the phase behavior in nanocolloidal suspensions.

  11. Elasticity of Demand for Labor: A Cross-Section Study of Wood Products Industries.

    ERIC Educational Resources Information Center

    Dreessen, Erwin A. J.

    This dissertation deals with the relationship between wages and employment in five industry classifications covering mullwork and furniture plants. Census and other data for 1958, 1963 and 1967 are used, as well as data for the three years combined. The data are on the state level. The relationship is estimated within a simultaneous equation…

  12. Computational Imaging in Demanding Conditions

    DTIC Science & Technology

    2015-11-18

    interest in nanoscience in many research fields like  physics,  chemistry , and biology, including the  environmental  fate of the  produced nano-objects...to the Air Force; namely, the removal of disturbances due to demanding physical and environmental conditions. We considered degradations of interest...of  disturbances due to demanding physical and  environmental  conditions. We considered  degradations of interest that can be caused by a number of

  13. Elastic proteins: biological roles and mechanical properties.

    PubMed Central

    Gosline, John; Lillie, Margo; Carrington, Emily; Guerette, Paul; Ortlepp, Christine; Savage, Ken

    2002-01-01

    The term 'elastic protein' applies to many structural proteins with diverse functions and mechanical properties so there is room for confusion about its meaning. Elastic implies the property of elasticity, or the ability to deform reversibly without loss of energy; so elastic proteins should have high resilience. Another meaning for elastic is 'stretchy', or the ability to be deformed to large strains with little force. Thus, elastic proteins should have low stiffness. The combination of high resilience, large strains and low stiffness is characteristic of rubber-like proteins (e.g. resilin and elastin) that function in the storage of elastic-strain energy. Other elastic proteins play very different roles and have very different properties. Collagen fibres provide exceptional energy storage capacity but are not very stretchy. Mussel byssus threads and spider dragline silks are also elastic proteins because, in spite of their considerable strength and stiffness, they are remarkably stretchy. The combination of strength and extensibility, together with low resilience, gives these materials an impressive resistance to fracture (i.e. toughness), a property that allows mussels to survive crashing waves and spiders to build exquisite aerial filters. Given this range of properties and functions, it is probable that elastic proteins will provide a wealth of chemical structures and elastic mechanisms that can be exploited in novel structural materials through biotechnology. PMID:11911769

  14. Adaptive Quality of Transmission Control in Elastic Optical Network

    NASA Astrophysics Data System (ADS)

    Cai, Xinran

    Optical fiber communication is becoming increasingly important due to the burgeoning demand in the internet capacity. However, traditional wavelength division multiplexing (WDM) technique fails to address such demand because of its inefficient spectral utilization. As a result, elastic optical networking (EON) has been under extensive investigation recently. Such network allows sub-wavelength and super-wavelength channel accommodation, and mitigates the stranded bandwidth problem in the WDM network. In addition, elastic optical network is also able to dynamically allocate the spectral resources of the network based on channel conditions and impairments, and adaptively control the quality of transmission of a channel. This application requires two aspects to be investigated: an efficient optical performance monitoring scheme and networking control and management algorithms to reconfigure the network in a dynamic fashion. This thesis focuses on the two aspects discussed above about adaptive QoT control. We demonstrated a supervisory channel method for optical signal to noise ratio (OSNR) and chromatic dispersion (CD) monitoring. In addition, our proof-of-principle testbed experiments show successful impairment aware reconfiguration of the network with modulation format switching (MFS) only and MFS combined with lightpath rerouting (LR) for hundred-GHz QPSK superchannels undergoing time-varying OSNR impairment.

  15. Towards Real Information on Demand.

    ERIC Educational Resources Information Center

    Barker, Philip

    The phrase "information on demand" is often used to describe situations in which digital electronic information can be delivered to particular points of need at times and in ways that are determined by the specific requirements of individual consumers or client groups. The advent of "mobile" computing equipment now makes the…

  16. Employer Demands from Business Graduates

    ERIC Educational Resources Information Center

    McMurray, Stephen; Dutton, Matthew; McQuaid, Ronald; Richard, Alec

    2016-01-01

    Purpose: The purpose of this paper is to report on research carried out with employers to determine demand for business and management skills in the Scottish workforce. Design/methodology/approach: The research used a questionnaire in which employers were interviewed (either telephone or face to face), completed themselves and returned by e-mail,…

  17. Projecting Electricity Demand in 2050

    SciTech Connect

    Hostick, Donna J.; Belzer, David B.; Hadley, Stanton W.; Markel, Tony; Marnay, Chris; Kintner-Meyer, Michael C. W.

    2014-07-01

    This paper describes the development of end-use electricity projections and load curves that were developed for the Renewable Electricity (RE) Futures Study (hereafter RE Futures), which explored the prospect of higher percentages (30% - 90%) of total electricity generation that could be supplied by renewable sources in the United States. As input to RE Futures, two projections of electricity demand were produced representing reasonable upper and lower bounds of electricity demand out to 2050. The electric sector models used in RE Futures required underlying load profiles, so RE Futures also produced load profile data in two formats: 8760 hourly data for the year 2050 for the GridView model, and in 2-year increments for 17 time slices as input to the Regional Energy Deployment System (ReEDS) model. The process for developing demand projections and load profiles involved three steps: discussion regarding the scenario approach and general assumptions, literature reviews to determine readily available data, and development of the demand curves and load profiles.

  18. Smart Buildings and Demand Response

    NASA Astrophysics Data System (ADS)

    Kiliccote, Sila; Piette, Mary Ann; Ghatikar, Girish

    2011-11-01

    Advances in communications and control technology, the strengthening of the Internet, and the growing appreciation of the urgency to reduce demand side energy use are motivating the development of improvements in both energy efficiency and demand response (DR) systems in buildings. This paper provides a framework linking continuous energy management and continuous communications for automated demand response (Auto-DR) in various times scales. We provide a set of concepts for monitoring and controls linked to standards and procedures such as Open Automation Demand Response Communication Standards (OpenADR). Basic building energy science and control issues in this approach begin with key building components, systems, end-uses and whole building energy performance metrics. The paper presents a framework about when energy is used, levels of services by energy using systems, granularity of control, and speed of telemetry. DR, when defined as a discrete event, requires a different set of building service levels than daily operations. We provide examples of lessons from DR case studies and links to energy efficiency.

  19. Residential electricity demand in Arkansas

    NASA Astrophysics Data System (ADS)

    Resendez, Ileana M.

    This study analyzes residential electricity demand in Arkansas. Explanatory variables utilized include real per capita income, residential electricity price, heating degree days, cooling degree days, and residential natural gas price. The results indicate that the income effect dominates the substitution effect given a real personal income increase and a decline in real electricity rates in the state of Arkansas during the period under study.

  20. Commercial Demand Module - NEMS Documentation

    EIA Publications

    2014-01-01

    Documents the objectives, analytical approach and development of the National Energy Modeling System (NEMS) Commercial Sector Demand Module. The report catalogues and describes the model assumptions, computational methodology, parameter estimation techniques, model source code, and forecast results generated through the synthesis and scenario development based on these components.

  1. [Fiscal policy, affordability and cross effects in the demand for tobacco products: the case of Uruguay].

    PubMed

    Carbajales, Alejandro Ramos; Curti, Dardo

    2010-01-01

    Uruguay, a country with a solid tobacco control policy since 2005 shows, contrary to expectations, an insignificant decrease in total tobacco products' sales in the last five years. The hypothesis is that on one side, changes in household income and the income elasticity of the demand for cigarettes were important countervailing factors in the demand of both products. The period 2005-2009 shows a large increase of 36% in household real income in Uruguay due to fast economic recovery after the 2002 crisis. The second factor is the interchangeability of roll your own and cigarettes and the impact on the demand of each product as a reaction to tax and price changes. The tax and price of roll your own tobacco remains substantially lower than that of cigarettes. This fact, and the increased substitution of roll your own for cigarettes seems to be the main reasons for the low impact of the policy of tobacco tax and price increases. This paper then consists of a revision of a 2004 study to estimate separate demands for both main tobacco products and obtain estimates for own price, cross price and income elasticities. Then, a simulation study was performed using the elasticities found and two scenarios of increases in household income: moderate (2.5% per year) and high (5% per year) confirming that countries where income is growing fast and with a potential for substitution towards cheaper products require substantial cigarette tax and price increases for a fiscal tobacco control policy to become effective.

  2. Demand Controlled Ventilation and Classroom Ventilation

    SciTech Connect

    Fisk, William J.; Mendell, Mark J.; Davies, Molly; Eliseeva, Ekaterina; Faulkner, David; Hong, Tienzen; Sullivan, Douglas P.

    2012-05-01

    This document summarizes a research effort on demand controlled ventilation and classroom ventilation. The research on demand controlled ventilation included field studies and building energy modeling.

  3. Price Elasticities for Energy Use in Buildings of the United States

    EIA Publications

    2014-01-01

    Energy demand tends to be responsive to changes in energy prices, a concept in economics known as price elasticity. Generally, an increase in a fuel price causes users to use less of that fuel or switch to a different fuel. The extent to which each of these changes takes place is of high importance to stakeholders in the energy sector and especially in energy planning. The purpose of this analysis is to determine fuel-price elasticities in stationary structures, particularly in the residential and commercial sectors.

  4. The alchemy of demand response: turning demand into supply

    SciTech Connect

    Rochlin, Cliff

    2009-11-15

    Paying customers to refrain from purchasing products they want seems to run counter to the normal operation of markets. Demand response should be interpreted not as a supply-side resource but as a secondary market that attempts to correct the misallocation of electricity among electric users caused by regulated average rate tariffs. In a world with costless metering, the DR solution results in inefficiency as measured by deadweight losses. (author)

  5. Addressing Energy Demand through Demand Response. International Experiences and Practices

    SciTech Connect

    Shen, Bo; Ghatikar, Girish; Ni, Chun Chun; Dudley, Junqiao; Martin, Phil; Wikler, Greg

    2012-06-01

    Demand response (DR) is a load management tool which provides a cost-effective alternative to traditional supply-side solutions to address the growing demand during times of peak electrical load. According to the US Department of Energy (DOE), demand response reflects “changes in electric usage by end-use customers from their normal consumption patterns in response to changes in the price of electricity over time, or to incentive payments designed to induce lower electricity use at times of high wholesale market prices or when system reliability is jeopardized.” 1 The California Energy Commission (CEC) defines DR as “a reduction in customers’ electricity consumption over a given time interval relative to what would otherwise occur in response to a price signal, other financial incentives, or a reliability signal.” 2 This latter definition is perhaps most reflective of how DR is understood and implemented today in countries such as the US, Canada, and Australia where DR is primarily a dispatchable resource responding to signals from utilities, grid operators, and/or load aggregators (or DR providers).

  6. Euler-Lagrange Elasticity: elasticity without stress or strain

    NASA Astrophysics Data System (ADS)

    Hardy, Humphrey

    2014-03-01

    A Euler-Lagrange (E-L) approach to elasticity is proposed that produces differential equations of elasticity without the need to define stress or strain tensors. The positions of the points within the body are the independent parameters instead of strain. Force replaces stress. The advantage of this approach is that the E-L differential equations are the same for both infinitesimal and finite deformations. Material properties are expressed in terms of the energy of deformation. The energy is expressed as a function of the principal invariants of the deformation gradient tensor. This scalar invariant representation of the energy of deformation enters directly into the E-L differential equations so that there is no need to define fourth order tensor material properties. By experimentally measuring the force and displacement of materials the functional form of the energy of deformation can be determined. The E-L differential equations can be input directly into finite element, finite difference, or other numerical models. If desired, stress and stain can be calculated as dependent parameters.

  7. Elasticity of Poissonian fiber networks

    NASA Astrophysics Data System (ADS)

    Åström, J. A.; Mäkinen, J. P.; Alava, M. J.; Timonen, J.

    2000-05-01

    An effective-medium model is introduced for the elasticity of two-dimensional random fiber networks. These networks are commonly used as basic models of heterogeneous fibrous structures such as paper. Using the exact Poissonian statistics to describe the microscopic geometry of the network, the tensile modulus can be expressed by a single-parameter function. This parameter depends on the network density and fiber dimensions, which relate the macroscopic modulus to the relative importance of axial and bending deformations of the fibers. The model agrees well with simulation results and experimental findings. We also discuss the possible generalizations of the model.

  8. Advertising increases demand for vasectomy.

    PubMed

    Mehta, M; Mckenzie, M

    1996-01-01

    The recent evaluation of a 2-year no-scalpel vasectomy (NSV) training program providing on-site, hands-on training for physicians working in 43 publicly funded health centers in 17 states found that demand for vasectomy in low-income and minority communities in the US increased following the implementation of innovative advertising strategies. The program also provided sites with surgical instruments, training materials, a press kit, and some help with public information activities. Participating clinics used a range of formal and informal advertising strategies, including radio and printed advertisements, to inform potential clients about vasectomy services. Many interested clients presented to clinics to undergo vasectomy once they had been made aware of the service and its availability. Several providers even stated that advertising caused the demand for vasectomy to exceed their capacity to provide services. The provision of low- or no-cost procedures helped to attract new clients.

  9. Evaluation of a Hybrid Elastic EVA Glove

    NASA Technical Reports Server (NTRS)

    Korona, F. Adam; Akin, David

    2002-01-01

    The hybrid elastic design is based upon an American Society for Engineering Education (ASEE) glove designed by at the Space Systems Laboratory (SSL) in 1985. This design uses an elastic restraint layer instead of convolute joints to achieve greater dexterity and mobility during EVA (extravehicular activity). Two pilot studies and a main study were conducted using the hybrid elastic glove and 4000-series EMU (extravehicular activity unit) glove. Data on dexterity performance, joint range of motion, grip strength and perceived exertion was assessed for the EMU and hybrid elastic gloves with correlations to a barehanded condition. During this study, 30 test subjects performed multiple test sessions using a hybrid elastic glove and a 4000- series shuttle glove in a 4.3psid pressure environment. Test results to date indicate that the hybrid elastic glove performance is approximately similar to the performance of the 4000-series glove.

  10. Elastic, Conductive, Polymeric Hydrogels and Sponges

    PubMed Central

    Lu, Yun; He, Weina; Cao, Tai; Guo, Haitao; Zhang, Yongyi; Li, Qingwen; Shao, Ziqiang; Cui, Yulin; Zhang, Xuetong

    2014-01-01

    As a result of inherent rigidity of the conjugated macromolecular chains resulted from the delocalized π-electron system along the polymer backbone, it has been a huge challenge to make conducting polymer hydrogels elastic by far. Herein elastic and conductive polypyrrole hydrogels with only conducting polymer as the continuous phase have been simply synthesized in the indispensable conditions of 1) mixed solvent, 2) deficient oxidant, and 3) monthly secondary growth. The elastic mechanism and oxidative polymerization mechanism on the resulting PPy hydrogels have been discussed. The resulting hydrogels show some novel properties, e.g., shape memory elasticity, fast functionalization with various guest objects, and fast removal of organic infectants from aqueous solutions, all of which cannot be observed from traditional non-elastic conducting polymer counterparts. What's more, light-weight, elastic, and conductive organic sponges with excellent stress-sensing behavior have been successfully achieved via using the resulting polypyrrole hydrogels as precursors. PMID:25052015

  11. Testing simulation and structural models with applications to energy demand

    NASA Astrophysics Data System (ADS)

    Wolff, Hendrik

    2007-12-01

    This dissertation deals with energy demand and consists of two parts. Part one proposes a unified econometric framework for modeling energy demand and examples illustrate the benefits of the technique by estimating the elasticity of substitution between energy and capital. Part two assesses the energy conservation policy of Daylight Saving Time and empirically tests the performance of electricity simulation. In particular, the chapter "Imposing Monotonicity and Curvature on Flexible Functional Forms" proposes an estimator for inference using structural models derived from economic theory. This is motivated by the fact that in many areas of economic analysis theory restricts the shape as well as other characteristics of functions used to represent economic constructs. Specific contributions are (a) to increase the computational speed and tractability of imposing regularity conditions, (b) to provide regularity preserving point estimates, (c) to avoid biases existent in previous applications, and (d) to illustrate the benefits of our approach via numerical simulation results. The chapter "Can We Close the Gap between the Empirical Model and Economic Theory" discusses the more fundamental question of whether the imposition of a particular theory to a dataset is justified. I propose a hypothesis test to examine whether the estimated empirical model is consistent with the assumed economic theory. Although the proposed methodology could be applied to a wide set of economic models, this is particularly relevant for estimating policy parameters that affect energy markets. This is demonstrated by estimating the Slutsky matrix and the elasticity of substitution between energy and capital, which are crucial parameters used in computable general equilibrium models analyzing energy demand and the impacts of environmental regulations. Using the Berndt and Wood dataset, I find that capital and energy are complements and that the data are significantly consistent with duality

  12. Disruptive innovation: the demand side.

    PubMed

    Havighurst, Clark C

    2008-01-01

    The notion of disruptive innovation provides a welcome framework for considering the prospects for low-cost alternatives in American medicine. Such innovations as have been seen, however, are largely the result of demand by patients paying their own bills because they have high-deductible coverage or are uninsured. Many other cost-saving innovations are discouraged by financing systems that are themselves largely immune to competition from disruptive innovators.

  13. 46 CFR 169.689 - Demand loads.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Demand loads. 169.689 Section 169.689 Shipping COAST... Electrical Electrical Installations on Vessels of 100 Gross Tons and Over § 169.689 Demand loads. Demand loads must meet § 111.60-7 of this chapter except that smaller demand loads for motor feeders...

  14. 46 CFR 169.689 - Demand loads.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Demand loads. 169.689 Section 169.689 Shipping COAST... Electrical Electrical Installations on Vessels of 100 Gross Tons and Over § 169.689 Demand loads. Demand loads must meet § 111.60-7 of this chapter except that smaller demand loads for motor feeders...

  15. Automation of energy demand forecasting

    NASA Astrophysics Data System (ADS)

    Siddique, Sanzad

    Automation of energy demand forecasting saves time and effort by searching automatically for an appropriate model in a candidate model space without manual intervention. This thesis introduces a search-based approach that improves the performance of the model searching process for econometrics models. Further improvements in the accuracy of the energy demand forecasting are achieved by integrating nonlinear transformations within the models. This thesis introduces machine learning techniques that are capable of modeling such nonlinearity. Algorithms for learning domain knowledge from time series data using the machine learning methods are also presented. The novel search based approach and the machine learning models are tested with synthetic data as well as with natural gas and electricity demand signals. Experimental results show that the model searching technique is capable of finding an appropriate forecasting model. Further experimental results demonstrate an improved forecasting accuracy achieved by using the novel machine learning techniques introduced in this thesis. This thesis presents an analysis of how the machine learning techniques learn domain knowledge. The learned domain knowledge is used to improve the forecast accuracy.

  16. Energy demand and population change.

    PubMed

    Allen, E L; Edmonds, J A

    1981-09-01

    During the post World War 2 years energy consumption has grown 136% while population grew about 51%; per capita consumption of energy expanded, therefore, about 60%. For a given population size, demographic changes mean an increase in energy needs; for instance the larger the group of retirement age people, the smaller their energy needs than are those for a younger group. Estimates indicate that by the year 2000 the energy impact will be toward higher per capita consumption with 60% of the population in the 19-61 age group of workers. Rising female labor force participation will increase the working group even more; it has also been found that income and energy grow at a proportional rate. The authors predict that gasoline consumption within the US will continue to rise with availability considering the larger number of female drivers and higher per capita incomes. The flow of illegal aliens (750,000/year) will have a major impact on income and will use greater amounts of energy than can be expected. A demographic change which will lower energy demands will be the slowdown of the rate of household formation caused by the falling number of young adults. The response of energy demand to price changes is small and slow but incomes play a larger role as does the number of personal automobiles and social changes affecting household formation. Households, commercial space, transportation, and industry are part of every demand analysis and population projections play a major role in determining these factors.

  17. Inversion of elastic impedance for unconsolidated sediments

    USGS Publications Warehouse

    Lee, Myung W.

    2006-01-01

    Elastic properties of gas-hydrate-bearing sediments are important for quantifying gas hydrate amounts as well as discriminating the gas hydrate effect on velocity from free gas or pore pressure. This paper presents an elastic inversion method for estimating elastic properties of gas-hydrate-bearing sediments from angle stacks using sequential inversion of P-wave impedance from the zero-offset stack and S-wave impedance from the far-offset stack without assuming velocity ratio.

  18. Multi-spectral photoacoustic elasticity tomography

    PubMed Central

    Liu, Yubin; Yuan, Zhen

    2016-01-01

    The goal of this work was to develop and validate a spectrally resolved photoacoustic imaging method, namely multi-spectral photoacoustic elasticity tomography (PAET) for quantifying the physiological parameters and elastic modulus of biological tissues. We theoretically and experimentally examined the PAET imaging method using simulations and in vitro experimental tests. Our simulation and in vitro experimental results indicated that the reconstructions were quantitatively accurate in terms of sizes, the physiological and elastic properties of the targets. PMID:27699101

  19. Elastic scattering with weakly bound projectiles

    SciTech Connect

    Figueira, J. M.; Abriola, D.; Arazi, A.; Capurro, O. A.; Marti, G. V.; Martinez Heinmann, D.; Pacheco, A. J.; Testoni, J. E.; Barbara, E. de; Fernandez Niello, J. O.; Padron, I.; Gomes, P. R. S.; Lubian, J.

    2007-02-12

    Possible effects of the break-up channel on the elastic scattering threshold anomaly has been investigated. We used the weakly bound 6,7Li nuclei, which is known to undergo break-up, as projectiles in order to study the elastic scattering on a 27Al target. In this contribution we present preliminary results of these experiments, which were analyzed in terms of the Optical Model and compared with other elastic scattering data using weakly bound nuclei as projectile.

  20. Microscopic theory of rubber elasticity.

    PubMed

    Oyerokun, Folusho T; Schweizer, Kenneth S

    2004-05-15

    A microscopic integral equation theory of elasticity in polymer liquids and networks is developed which addresses the nonclassical problem of the consequences of interchain repulsive interactions and packing correlations on mechanical response. The theory predicts strain induced softening, and a nonclassical intermolecular contribution to the linear modulus. The latter is of the same magnitude as the classical single chain entropy contribution at low polymer concentrations, but becomes much more important in the melt state, and dominant as the isotropic-nematic liquid crystal phase transition is approached. Comparison of the calculated stress-strain curve and induced nematic order parameter with computer simulations show good agreement. A nearly quadratic dependence of the linear elastic modulus on segmental concentration is found, as well as a novel fractional power law dependence on degree of polymerization. Quantitative comparison of the theory with experiments on polydimethylsiloxane networks are presented and good agreement is found. However, a nonzero modulus in the long chain limit is not predicted since quenched chemical crosslinks and trapped entanglements are not explicitly taken into account. The theory is generalizable to treat the structure, thermodynamics and mechanical response of nematic elastomers.

  1. Electron-Hydrogen Elastic Scattering

    NASA Technical Reports Server (NTRS)

    Bhatia, A. K.

    2004-01-01

    Scattering by single-electron systems is always of interest because the wave function of the target is known exactly. Various approximations have been employed to take into account distortion produced in the target. Among them are the method of polarized orbitals and the close coupling approximation. Recently, e-H and e-He+ S-wave scattering in the elastic region has been studied using the Feshbach projection operator formalism. In this approach, the usual Hartree-Fock and exchange potentials are augmented by an optical potential and the resulting phase shifts have rigorous lower bounds. Now this method is being applied to the e-H P-wave scattering in the elastic region. The number of terms in the Hylleraas-type wave function for the 1,3 P phase shifts is 84 and the resulting phase shifts (preliminary) are given. The results have been given up to five digits because to that accuracy they are rigorous lower bounds. They are in general agreement with the variational (VAR) results of Armstead, and those obtained from the intermediate energy R-matrix method (RM) of Scholz et al., and the finite element method (FEM) of Botero and Shertzer. The later two methods do not provide any bounds on phase shifts.

  2. Pneumatic Variable Series Elastic Actuator.

    PubMed

    Zheng, Hao; Wu, Molei; Shen, Xiangrong

    2016-08-01

    Inspired by human motor control theory, stiffness control is highly effective in manipulation and human-interactive tasks. The implementation of stiffness control in robotic systems, however, has largely been limited to closed-loop control, and suffers from multiple issues such as limited frequency range, potential instability, and lack of contribution to energy efficiency. Variable-stiffness actuator represents a better solution, but the current designs are complex, heavy, and bulky. The approach in this paper seeks to address these issues by using pneumatic actuator as a variable series elastic actuator (VSEA), leveraging the compressibility of the working fluid. In this work, a pneumatic actuator is modeled as an elastic element with controllable stiffness and equilibrium point, both of which are functions of air masses in the two chambers. As such, for the implementation of stiffness control in a robotic system, the desired stiffness/equilibrium point can be converted to the desired chamber air masses, and a predictive pressure control approach is developed to control the timing of valve switching to obtain the desired air mass while minimizing control action. Experimental results showed that the new approach in this paper requires less expensive hardware (on-off valve instead of proportional valve), causes less control action in implementation, and provides good control performance by leveraging the inherent dynamics of the actuator.

  3. Hummingbird tongues are elastic micropumps.

    PubMed

    Rico-Guevara, Alejandro; Fan, Tai-Hsi; Rubega, Margaret A

    2015-08-22

    Pumping is a vital natural process, imitated by humans for thousands of years. We demonstrate that a hitherto undocumented mechanism of fluid transport pumps nectar onto the hummingbird tongue. Using high-speed cameras, we filmed the tongue-fluid interaction in 18 hummingbird species, from seven of the nine main hummingbird clades. During the offloading of the nectar inside the bill, hummingbirds compress their tongues upon extrusion; the compressed tongue remains flattened until it contacts the nectar. After contact with the nectar surface, the tongue reshapes filling entirely with nectar; we did not observe the formation of menisci required for the operation of capillarity during this process. We show that the tongue works as an elastic micropump; fluid at the tip is driven into the tongue's grooves by forces resulting from re-expansion of a collapsed section. This work falsifies the long-standing idea that capillarity is an important force filling hummingbird tongue grooves during nectar feeding. The expansive filling mechanism we report in this paper recruits elastic recovery properties of the groove walls to load nectar into the tongue an order of magnitude faster than capillarity could. Such fast filling allows hummingbirds to extract nectar at higher rates than predicted by capillarity-based foraging models, in agreement with their fast licking rates.

  4. Hummingbird tongues are elastic micropumps

    PubMed Central

    Rico-Guevara, Alejandro; Fan, Tai-Hsi; Rubega, Margaret A.

    2015-01-01

    Pumping is a vital natural process, imitated by humans for thousands of years. We demonstrate that a hitherto undocumented mechanism of fluid transport pumps nectar onto the hummingbird tongue. Using high-speed cameras, we filmed the tongue–fluid interaction in 18 hummingbird species, from seven of the nine main hummingbird clades. During the offloading of the nectar inside the bill, hummingbirds compress their tongues upon extrusion; the compressed tongue remains flattened until it contacts the nectar. After contact with the nectar surface, the tongue reshapes filling entirely with nectar; we did not observe the formation of menisci required for the operation of capillarity during this process. We show that the tongue works as an elastic micropump; fluid at the tip is driven into the tongue's grooves by forces resulting from re-expansion of a collapsed section. This work falsifies the long-standing idea that capillarity is an important force filling hummingbird tongue grooves during nectar feeding. The expansive filling mechanism we report in this paper recruits elastic recovery properties of the groove walls to load nectar into the tongue an order of magnitude faster than capillarity could. Such fast filling allows hummingbirds to extract nectar at higher rates than predicted by capillarity-based foraging models, in agreement with their fast licking rates. PMID:26290074

  5. Elastic moduli of pyrope rich garnets

    NASA Astrophysics Data System (ADS)

    Pandey, B. K.; Pandey, A. K.; Singh, C. K.

    2013-06-01

    The elastic properties of minerals depend on its composition, crystal structure, temperature and level of defects. The elastic parameters are important for the interpretation of the structure and composition of the garnet rich family. In present work we have calculated the elastic moduli such as isothermal bulk modulus, Young's modulus and Shear modulus over a wide range of temperature from 300 K to 1000 K by using Birch EOS and Poirrier Tarantola equation of state. The obtained results are compared with the experimental results obtained by measuring the elastic moduli of single crystal. The calculated results show that the logarithmic isothermal EOS does not cooperate well with experimental results.

  6. Faraday wave lattice as an elastic metamaterial.

    PubMed

    Domino, L; Tarpin, M; Patinet, S; Eddi, A

    2016-05-01

    Metamaterials enable the emergence of novel physical properties due to the existence of an underlying subwavelength structure. Here, we use the Faraday instability to shape the fluid-air interface with a regular pattern. This pattern undergoes an oscillating secondary instability and exhibits spontaneous vibrations that are analogous to transverse elastic waves. By locally forcing these waves, we fully characterize their dispersion relation and show that a Faraday pattern presents an effective shear elasticity. We propose a physical mechanism combining surface tension with the Faraday structured interface that quantitatively predicts the elastic wave phase speed, revealing that the liquid interface behaves as an elastic metamaterial.

  7. Rubber Elasticity in Highly Crosslinked Polyesters.

    DTIC Science & Technology

    Esters, *Polymers, *Elastic properties, Rubber, Propylene glycol , Maleic acid, Anhydrides, Phthalic acids, Mechanical properties, Molecular structure, Crosslinking(Chemistry), Polymerization, Styrenes, Temperature, Transition temperature, Molecular weight

  8. A Methodology for Estimating Large-Customer Demand Response MarketPotential

    SciTech Connect

    Goldman, Charles; Hopper, Nicole; Bharvirkar, Ranjit; Neenan,Bernie; Cappers,Peter

    2007-08-01

    Demand response (DR) is increasingly recognized as an essential ingredient to well-functioning electricity markets. DR market potential studies can answer questions about the amount of DR available in a given area and from which market segments. Several recent DR market potential studies have been conducted, most adapting techniques used to estimate energy-efficiency (EE) potential. In this scoping study, we: reviewed and categorized seven recent DR market potential studies; recommended a methodology for estimating DR market potential for large, non-residential utility customers that uses price elasticities to account for behavior and prices; compiled participation rates and elasticity values from six DR options offered to large customers in recent years, and demonstrated our recommended methodology with large customer market potential scenarios at an illustrative Northeastern utility. We observe that EE and DR have several important differences that argue for an elasticity approach for large-customer DR options that rely on customer-initiated response to prices, rather than the engineering approaches typical of EE potential studies. Base-case estimates suggest that offering DR options to large, non-residential customers results in 1-3% reductions in their class peak demand in response to prices or incentive payments of $500/MWh. Participation rates (i.e., enrollment in voluntary DR programs or acceptance of default hourly pricing) have the greatest influence on DR impacts of all factors studied, yet are the least well understood. Elasticity refinements to reflect the impact of enabling technologies and response at high prices provide more accurate market potential estimates, particularly when arc elasticities (rather than substitution elasticities) are estimated.

  9. An analysis of long and medium-haul air passenger demand, volume 1

    NASA Technical Reports Server (NTRS)

    Eriksen, S. E.

    1978-01-01

    A basic model was developed which is a two equation pair econometric system in which air passenger demand and airline level-of-service are the endogenous variables. The model aims to identify the relationship between each of these two variables and its determining factors, and to identify the interaction of demand and level-of-service with each other. The selected variable for the measure of air passenger traffic activity in a given pair market is defined as the number of passengers in a given time that originate in one region and fly to the other region for purposes other than to make a connection to a third region. For medium and long haul markets, the model seems to perform better for larger markets. This is due to a specification problem regarding the route structure variable. In larger markets, a greater percentage of nonlocal passengers are accounted for by this variable. Comparing the estimated fare elasticities of long and medium haul markets, it appears that air transportation demand is more price elastic in longer haul markets. Long haul markets demand will saturate with a fewer number of departures than will demand in medium haul markets.

  10. The Effect of Temperature on the Electricity Demand: An Empirical Investigation

    NASA Astrophysics Data System (ADS)

    Kim, H.; Kim, I. G.; Park, K. J.; Yoo, S. H.

    2015-12-01

    This paper attempts to estimate the electricity demand function in Korea with quarterly data of average temperature, GDP and electricity price over the period 2005-2013. We apply lagged dependent variable model and ordinary least square method as a robust approach to estimating the parameters of the electricity demand function. The results show that short-run price and income elasticities of the electricity demand are estimated to be -0.569 and 0.631 respectively. They are statistically significant at the 1% level. Moreover, long-run income and price elasticities are estimated to be 1.589 and -1.433 respectively. Both of results reveal that the demand for electricity demand is about 15.2℃. It is shown that power of explanation and goodness-of-fit statistics are improved in the use of the lagged dependent variable model rather than conventional model. Acknowledgements: This research was carried out as a part of "Development and application of technology for weather forecast" supported by the 2015 National Institute of Meteorological Research (NIMR) in the Korea Meteorological Administration.

  11. Supplier-induced demand: re-examining identification and misspecification in cross-sectional analysis.

    PubMed

    Peacock, Stuart J; Richardson, Jeffrey R J

    2007-09-01

    This paper re-examines criticisms of cross-sectional methods used to test for supplier-induced demand (SID) and re-evaluates the empirical evidence using data from Australian medical services. Cross-sectional studies of SID have been criticised on two grounds. First, and most important, the inclusion of the doctor supply in the demand equation leads to an identification problem. This criticism is shown to be invalid, as the doctor supply variable is stochastic and depends upon a variety of other variables including the desirability of the location. Second, cross-sectional studies of SID fail diagnostic tests and produce artefactual findings due to model misspecification. Contrary to this, the re-evaluation of cross-sectional Australian data indicate that demand equations that do not include the doctor supply are misspecified. Empirical evidence from the re-evaluation of Australian medical services data supports the notion of SID. Demand and supply equations are well specified and have very good explanatory power. The demand equation is identified and the desirability of a location is an important predictor of the doctor supply. Results show an average price elasticity of demand of 0.22 and an average elasticity of demand with respect to the doctor supply of 0.46, with the impact of SID becoming stronger as the doctor supply rises. The conclusion we draw from this paper is that two of the main criticisms of the empirical evidence supporting the SID hypothesis have been inappropriately levelled at the methods used. More importantly, SID provides a satisfactory, and robust, explanation of the empirical data on the demand for medical services in Australia.

  12. Evaluation of Demand Prediction Techniques

    DTIC Science & Technology

    1987-03-01

    Road Bethesda, Maryland 20817 5886 JiZ A q C64 ACKNOWLEDGMENTS Robert Arnberg of LMI deserves credit for assembling many files cf D041 data for...the best techniques of those we studied. • Use of a Poisson or constant variance-to-mean ratio (VMR) leads to poor allocation of resources. Treating...the program element is not in the D041 record or is zero for some quarters with positive demand, or has apparent errors that lead to a less stable

  13. Elasticity of polymeric nanocolloidal particles

    NASA Astrophysics Data System (ADS)

    Riest, Jonas; Athanasopoulou, Labrini; Egorov, Sergei A.; Likos, Christos N.; Ziherl, Primož

    2015-11-01

    Softness is an essential mechanical feature of macromolecular particles such as polymer-grafted nanocolloids, polyelectrolyte networks, cross-linked microgels as well as block copolymer and dendrimer micelles. Elasticity of individual particles directly controls their swelling, wetting, and adsorption behaviour, their aggregation and self-assembly as well as structural and rheological properties of suspensions. Here we use numerical simulations and self-consistent field theory to study the deformation behaviour of a single spherical polymer brush upon diametral compression. We observe a universal response, which is rationalised using scaling arguments and interpreted in terms of two coarse-grained models. At small and intermediate compressions the deformation can be accurately reproduced by modelling the brush as a liquid drop, whereas at large compressions the brush behaves as a soft ball. Applicable far beyond the pairwise-additive small-strain regime, the models may be used to describe microelasticity of nanocolloids in severe confinement including dense disordered and crystalline phases.

  14. High elastic modulus polymer electrolytes

    DOEpatents

    Balsara, Nitash Pervez; Singh, Mohit; Eitouni, Hany Basam; Gomez, Enrique Daniel

    2013-10-22

    A polymer that combines high ionic conductivity with the structural properties required for Li electrode stability is useful as a solid phase electrolyte for high energy density, high cycle life batteries that do not suffer from failures due to side reactions and dendrite growth on the Li electrodes, and other potential applications. The polymer electrolyte includes a linear block copolymer having a conductive linear polymer block with a molecular weight of at least 5000 Daltons, a structural linear polymer block with an elastic modulus in excess of 1.times.10.sup.7 Pa and an ionic conductivity of at least 1.times.10.sup.-5 Scm.sup.-1. The electrolyte is made under dry conditions to achieve the noted characteristics.

  15. Elastic Suppression of Viscous Fingering

    NASA Astrophysics Data System (ADS)

    Peng, Gunnar; Lister, John

    2016-11-01

    Consider peeling an elastic tape or beam away from a rigid base to which it is stuck by a film of viscous liquid. The peeling motion requires air to invade the viscous liquid and is thus susceptible to the Saffman-Taylor fingering instability. We analyse the fundamental travelling-wave solution and show that the advancing air-liquid interface remains linearly stable at higher capillary numbers than in a standard Hele-Shaw cell. A short-wavelength expansion yields an analytical expression for the growth rate which is valid for all unstable modes throughout the parameter space, allowing us to identify and quantify four distinct physical mechanisms that each help suppress the instability. Applying our method to the experiments by Pihler-Puzovic et al. (2012) reveals that the radial geometry and time-variation stabilize the system further.

  16. Assessing economic and demographic factors that influence United States dairy demand.

    PubMed

    Davis, C G; Yen, S T; Dong, D; Blayney, D P

    2011-07-01

    Low-fat dairy products are key components of a healthy diet for all Americans. As the USDA increases its focus on nutrition and healthy eating, it is important to understand the underlying demands for dairy products, both the healthy and the less healthy ones. The consumption of fluid milk products has decreased over the last decade, whereas milk used for manufactured dairy products such as cheese, ice cream, yogurt, and butter, and for use as an ingredient in other food products, has risen. The objective of this study is to determine the effects of changes in demographic variables, retail prices, and total dairy expenditure on at-home consumption of dairy products, using purchase data from Nielsen 2007 Homescan (ACNielsen, New York, NY) data. To derive the demand elasticities for 16 products, a censored Almost Ideal Demand System model is used. Results reveal that demographic variables do have effects on the purchase of the 16 products, and own-price elasticities are 1 or greater for all 16 products for both uncompensated and compensated elasticities except 4: ice cream, refrigerated yogurt, processed cheese, and margarine. A substitution relationship exists among all fluid milk categories, natural and processed cheese, low-fat ice cream, and refrigerated yogurt, butter, and margarine.

  17. An improved scheduled traffic model utilizing bandwidth splitting in elastic optical networks

    NASA Astrophysics Data System (ADS)

    Vyas, Upama; Prakash, Shashi

    2016-07-01

    The surge of traffic in today's networks gave birth to elastic optical networking paradigm. In this paper, first we propose to use the scheduled traffic model (STM) in elastic optical networks (EONs) to ensure guaranteed availability of resources to demands which enter into the network with a predetermined start and end times. In optical networks, such demands are referred to as scheduled lightpath demands (SLDs). To increase the amount of bandwidth accepted in network, next we introduce a time aware routing and spectrum assignment (TA-RSA) approach. We observed that provisioning of bulky SLDs has become more challenging in EONs due to enforcement of RSA constraints. To address this challenge, we improve the proposed STM and designed three heuristics for its implementation in EONs. In this work, we collectively refer to these heuristics as bandwidth segmented RSA (BSRSA). The improved STM (iSTM) allows splitting of SLDs in bandwidth dimension by utilizing the knowledge of attributes viz. demand holding time, overlapping in time and bandwidth requested by SLDs. Our numerical results show that BSRSA consistently outperformed over TA-RSA under all distinctive experimental cases that we considered and achieved fairness in serving heterogeneous bandwidth SLDs. The impact of splitting on the number and capacity of transponders at nodes is also gauged. It is observed that ingenious splitting of demands increases the number of resources (on links and nodes) used, and their utilization, leading to an increase in bandwidth accepted in the network.

  18. Ultrasonic System Measures Elastic Properties Of Composites

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Mal, Ajit K.

    1993-01-01

    Measurements with leaky Lamb waves yield data on properties and defects of panels. System nondestructively measures elastic properties of, and defects in, panel of laminated fiber/matrix material. Ultrasonic transducers operating in pitch/catch mode excite and detect leaky Lamb waves in specimen. Elastic properties of specimen and defects within it characterized from dispersion curves of Lamb waves.

  19. Study of Nonlinear Oscillations of Elastic Membrane

    DTIC Science & Technology

    2006-09-26

    Nonlinear Elastic Membrane Oscillations by Eigenfunction Expansion, WSEAS Transactions of Systems, 3 (4) (2004), 1430-1435. 2.V. Varlamov, Convolution...proceedings 1. A. Balogh and V. Varlamov, Analysis of Nonlinear Elastic Membrane Oscillations by Eigenfunction Expansion, 6th WSEAS International...Eigenfunction Expansion, 6th WSEAS International Conference on Algorithms, Scientific Computing, Modelling and Simulation, Cancun, Mexico, May 12--15

  20. 7 CFR 29.6013 - Elasticity.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Elasticity. 29.6013 Section 29.6013 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6013 Elasticity. The flexible, springy nature of the tobacco leaf...

  1. Simulation and control problems in elastic robots

    NASA Technical Reports Server (NTRS)

    Tadikonda, S. S. K.; Baruh, H.

    1989-01-01

    Computational issues associated with modeling and control of robots with revolute joints and elastic arms are considered. A manipulator with one arm and pinned at one end is considered to investigate various aspects of the modeling procedure and the model, and the effect of coupling between the rigid-body and the elastic motions. The rigid-body motion of a manipulator arm is described by means of a reference frame attached to the shadow beam, and the linear elastic operator denoting flexibility is defined with respect to this reference frame. The small elastic motion assumption coupled with the method of assumed modes is used to model the elasticity in the arm. It is shown that only terms up to quadratic in these model amplitudes need to be retained. An important aspect of the coupling between the rigid-body and the elastic motion is the centrifugal stiffening effect. This effect stiffens the elastic structure, as to be expected on physical grounds, gives rise to a time-varying inertia term for the rigid-body motion, and, in general, results in an effective inertia term smaller than the rigid-body inertia term. Simulation results are presented for an elastic beam pinned at one end and free at the other, and rotating in a horizontal plane, and control issues such as the order of the model, number of sensors, and modal extraction are examined within this context.

  2. Celestial mechanics of elastic bodies II

    NASA Astrophysics Data System (ADS)

    Beig, Robert; Schmidt, Bernd G.

    2017-04-01

    We construct time independent configurations describing a small elastic body moving in a circular orbit in the Schwarzschild spacetime. These configurations are relativistic versions of Newtonian solutions constructed by us previously. In the process we simplify and sharpen previous results of ours concerning elastic bodies in rigid rotation.

  3. Demand Side Bidding. Final Report

    SciTech Connect

    Spahn, Andrew

    2003-12-31

    This document sets forth the final report for a financial assistance award for the National Association of Regulatory Utility Commissioners (NARUC) to enhance coordination between the building operators and power system operators in terms of demand-side responses to Location Based Marginal Pricing (LBMP). Potential benefits of this project include improved power system reliability, enhanced environmental quality, mitigation of high locational prices within congested areas, and the reduction of market barriers for demand-side market participants. NARUC, led by its Committee on Energy Resources and the Environment (ERE), actively works to promote the development and use of energy efficiency and clean distributive energy policies within the framework of a dynamic regulatory environment. Electric industry restructuring, energy shortages in California, and energy market transformation intensifies the need for reliable information and strategies regarding electric reliability policy and practice. NARUC promotes clean distributive generation and increased energy efficiency in the context of the energy sector restructuring process. NARUC, through ERE's Subcommittee on Energy Efficiency, strives to improve energy efficiency by creating working markets. Market transformation seeks opportunities where small amounts of investment can create sustainable markets for more efficient products, services, and design practices.

  4. Demand Response Valuation Frameworks Paper

    SciTech Connect

    Heffner, Grayson

    2009-02-01

    While there is general agreement that demand response (DR) is a valued component in a utility resource plan, there is a lack of consensus regarding how to value DR. Establishing the value of DR is a prerequisite to determining how much and what types of DR should be implemented, to which customers DR should be targeted, and a key determinant that drives the development of economically viable DR consumer technology. Most approaches for quantifying the value of DR focus on changes in utility system revenue requirements based on resource plans with and without DR. This ''utility centric'' approach does not assign any value to DR impacts that lower energy and capacity prices, improve reliability, lower system and network operating costs, produce better air quality, and provide improved customer choice and control. Proper valuation of these benefits requires a different basis for monetization. The review concludes that no single methodology today adequately captures the wide range of benefits and value potentially attributed to DR. To provide a more comprehensive valuation approach, current methods such as the Standard Practice Method (SPM) will most likely have to be supplemented with one or more alternative benefit-valuation approaches. This report provides an updated perspective on the DR valuation framework. It includes an introduction and four chapters that address the key elements of demand response valuation, a comprehensive literature review, and specific research recommendations.

  5. Traveling Lamb wave in elastic metamaterial layer

    NASA Astrophysics Data System (ADS)

    Shu, Haisheng; Xu, Lihuan; Shi, Xiaona; Zhao, Lei; Zhu, Jie

    2016-10-01

    The propagation of traveling Lamb wave in single layer of elastic metamaterial is investigated in this paper. We first categorized the traveling Lamb wave modes inside an elastic metamaterial layer according to different combinations (positive or negative) of effective medium parameters. Then the impacts of the frequency dependence of effective parameters on dispersion characteristics of traveling Lamb wave were studied. Distinct differences could be observed when comparing the traveling Lamb wave along an elastic metamaterial layer with one inside the traditional elastic layer. We further examined in detail the traveling Lamb wave mode supported in elastic metamaterial layer, when the effective P and S wave velocities were simultaneously imaginary. It was found that the effective modulus ratio is the key factor for the existence of special traveling wave mode, and the main results were verified by FEM simulations from two levels: the level of effective medium and the level of microstructure unit cell.

  6. Breakdown of elasticity in amorphous solids

    NASA Astrophysics Data System (ADS)

    Biroli, Giulio; Urbani, Pierfrancesco

    2016-12-01

    What characterizes a solid is the way that it responds to external stresses. Ordered solids, such as crystals, exhibit an elastic regime followed by a plastic regime, both understood microscopically in terms of lattice distortion and dislocations. For amorphous solids the situation is instead less clear, and the microscopic understanding of the response to deformation and stress is a very active research topic. Several studies have revealed that even in the elastic regime the response is very jerky at low temperature, resembling very much the response of disordered magnetic materials. Here we show that in a very large class of amorphous solids this behaviour emerges upon decreasing temperature, as a phase transition, where standard elastic behaviour breaks down. At the transition all nonlinear elastic moduli diverge and standard elasticity theory no longer holds. Below the transition, the response to deformation becomes history- and time-dependent.

  7. Prospects for European labour demand.

    PubMed

    Lindley, R M

    1988-07-01

    The impact of economic and technological trends upon the level and structure of labor demand is examined, exploring the methods used to model the labor market and making special reference to demography and technology. Evidence on recent and prospective changes in labor demand is reviewed for France, Germany, Italy, the Netherlands, and the UK. The models used to explore future employment scenarios usually fail to incorporate the linkages required to fully analyze the various demographic-economic interactions. Further, this is not generally viewed as a limitation, given the time frame of most employment projections and their preoccupation with changes in the structure of labor demand. Medium-term multisectoral models tend to pay more attention to both demographic and technical change, but the treatment of both aspects is limited. The projections provide a framework for considering how both socioeconomic behavior and policy might change to achieve different outcomes. The greater a model's behavioral content, as expressed in its relationships between different variables, the greater the insight obtainable from simulation exercises. The 1st half of the 1970s was characterized by a reduction in German employment, representing the severest of European reactions to the oil crisis. The 2nd half of the decade recorded rapid growth in Italy and the Netherlands. The 1980s started with marked declines in Germany and the UK. Overall, the net gains of the 1970s were lost in the recession following the 2nd oil crisis. In none of the 5 countries studied does any realistic prospect emerge of achieving full employment before 2000. The most optimistic outcome is that unemployment will decline only slowly, it at all. The growth of both new forms and areas of employment will not compensate sufficiently for the loss of jobs elsewhere and the growth of labor supply. The industrial sector will continue to experience change in favor of the service sector but at a slower rate than during

  8. Cut Electric Bills by Controlling Demand

    ERIC Educational Resources Information Center

    Grumman, David L.

    1974-01-01

    Electric bills can be reduced by lowering electric consumption and by controlling demand -- the amount of electricity used at a certain point in time. Gives tips to help reduce electric demand at peak power periods. (Author/DN)

  9. Energy demand and population changes

    SciTech Connect

    Allen, E.L.; Edmonds, J.A.

    1980-12-01

    Since World War II, US energy demand has grown more rapidly than population, so that per capita consumption of energy was about 60% higher in 1978 than in 1947. Population growth and the expansion of per capita real incomes have led to a greater use of energy. The aging of the US population is expected to increase per capita energy consumption, despite the increase in the proportion of persons over 65, who consume less energy than employed persons. The sharp decline in the population under 18 has led to an expansion in the relative proportion of population in the prime-labor-force age groups. Employed persons are heavy users of energy. The growth of the work force and GNP is largely attributable to the growing participation of females. Another important consequence of female employment is the growth in ownership of personal automobiles. A third factor pushing up labor-force growth is the steady influx of illegal aliens.

  10. Soft lithography: masters on demand.

    PubMed

    Abdelgawad, Mohamed; Watson, Michael W L; Young, Edmond W K; Mudrik, Jared M; Ungrin, Mark D; Wheeler, Aaron R

    2008-08-01

    We report an ultra-rapid prototyping technique for forming microchannel networks for lab-on-a-chip applications, called masters on-demand. Channels are produced by replica molding on masters formed by laser printing on flexible copper printed circuit board (PCB) substrates. Masters of various designs and dimensions can be individually or mass produced in less than 10 minutes. Using this technique, we have fabricated channels as narrow as 100 microm with heights ranging between 9 microm and 70 microm. Multi-depth channel fabrication is also reported, using a two-step printing process. The functionality of devices formed in this manner is verified by performing in-channel electrophoretic separations and culture and analysis of primary mammalian cells.

  11. Video on demand internal trial

    NASA Astrophysics Data System (ADS)

    Sell, Chris

    1993-02-01

    This NYNEX internal trial was designed to test a variety of technical concepts pertaining to a true video on demand system. A three building complex was selected for the trial using coaxial and fiber optic transport systems. The trial period was approximately six weeks long with a total of eighteen movies available twenty four hours a day. A fully automated system was designed at the NYNEX Science and Technology Laboratory that incorporated video equipment and laser disk players. This system is controlled by a pair of Sun Microsystems workstations communicating via a local area network. Valuable knowledge was gained in the area of jukebox design, control systems, and menuing. Fiber optic delivery systems were investigated along with coaxial systems. The user base for this trial consisted of NYNEX employees instead of residential customers. Although the user base was not ideal, we gained insight into how people interact with a fully automated system.

  12. Positional demands of professional rugby.

    PubMed

    Lindsay, Angus; Draper, Nick; Lewis, John; Gieseg, Steven P; Gill, Nicholas

    2015-01-01

    Rugby union is a physically intense intermittent sport coupled with high force collisions. Each position within a team has specific requirements which are typically based on speed, size and skill. The aim of this study was to investigate the contemporary demands of each position and whether they can explain changes in psychophysiological stress. Urine and saliva samples were collected before and after five selected Super 15 rugby games from 37 players. Total neopterin (NP), cortisol and immunoglobulin A were analysed by SCX-high performance liquid chromatography and enzyme linked immunosorbent assay. Global positioning system software provided distance data, while live video analysis provided impact data. All contemporary demands were analysed as events per minute of game time. Forwards were involved in more total impacts, tackles and rucks compared to backs (p < 0.001), while backs were involved in more ball carries and covered more total distance and distance at high speed per minute of game time (p < 0.01). Loose forwards, inside and outside backs covered significantly more distance at high speed (p < 0.01), while there was a negligible difference with number of impacts between the forward positions. There was also minimal difference between positions in the percentage change in NP, cortisol and sIgA. The results indicate distance covered and number of impacts per minute of game time is position-dependent whereas changes in psychophysiological stress are independent. This information can be used to adapt training and recovery interventions to better prepare each position based on the physical requirements of the game.

  13. Displacement decomposition ACO based preconditioning of FEM elasticity systems

    NASA Astrophysics Data System (ADS)

    Sviercoski, R. F.; Margenov, S.

    2013-10-01

    Computational simulations of multiscale deformable porous media are routinely encountered as a part of research and development activities in a number of engineering, environmental and biomedical fields. The efficiency of multilevel iterative solution of such problems is a challenging topic on numerical methods for large-scale scientific computing, this is because predicting the mechanical behavior of such systems with hierarchical structures with multiple scales is very computationally demanding. Our main interest application concerns medium that has complex hierarchical morphology in the sense that features ranges from nanometer to millimeter scales. The goal of this work is to propose a computationally efficient numerical tool that can be used to perform everyday predictive simulations as an integral part of osteoporosis treatment, for example. To achieve that, highly heterogeneous media are considered that resembles trabecular bone tissues. The related fine-scale linear elasticity problem is of high contrast and high frequency. The finite element method (FEM) is applied for discretization of the related linear elasticity problem, using separable displacement decomposition. The new feature in this work is that at coarser levels, a block diagonal preconditioner is applied that incorporates an analytical effective tensor into the simulation, avoiding costly numerical solutions of local problems that are inherent in methods for multiscale problems. The robustness of the new proposed algorithm is measured by comparing the number of V-cycles necessary to resolve the considered multiscale problems with other well known techniques.

  14. Unifying the criteria of elastic stability of solids.

    PubMed

    Wang, Hao; Li, Mo

    2012-06-20

    The elastic stability criterion formulated by Born is based on the convexity requirement of the equilibrium free energy F of a stress-free crystal under small strain fluctuation, that demands the elastic constant tensor C to be positive definite, |C| > 0. For a crystal subject to an external stress, Hill specifies that for the crystal to be stable, the difference between its internal energy change δE and the work done to the system δW must be positive, i.e. δE - δW > 0. Polanyi, Frenkel, and Orowan proposed a different stability criterion based on stress increment for a loaded system, τ(ε + Δε) - τ(ε) > 0 until the limit is reached at dτ/dε = 0. Although known empirically, the formal connection between the different criteria has not been established rigorously. Using finite deformation theory, we show quite simply that the different formulations of the stability criteria originate from the same necessary condition for the convexity of the free energy of the system subject to external loading, f = F - W. However, in practice caution must be taken in implementation of the different criteria; they may lead to quite different results, especially when stability bifurcation occurs.

  15. The Aggregate Demand Curve: A Reply.

    ERIC Educational Resources Information Center

    Hansen, Richard B.; And Others

    1987-01-01

    Responds to claims about the instructional value of the downward-sloping aggregate demand curve in teaching principles of macroeconomics. Examines the effects of interest-rates and the role of money on demand curves. Concludes by arguing against the use of downward-sloping aggregate demand curves in textbooks. (RKM)

  16. 7 CFR 987.11 - Trade demand.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Trade demand. 987.11 Section 987.11 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... RIVERSIDE COUNTY, CALIFORNIA Order Regulating Handling Definitions § 987.11 Trade demand. Trade demand...

  17. 7 CFR 987.11 - Trade demand.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Trade demand. 987.11 Section 987.11 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... RIVERSIDE COUNTY, CALIFORNIA Order Regulating Handling Definitions § 987.11 Trade demand. Trade demand...

  18. Elastic metamaterial beam with remotely tunable stiffness

    NASA Astrophysics Data System (ADS)

    Qian, Wei; Yu, Zhengyue; Wang, Xiaole; Lai, Yun; Yellen, Benjamin B.

    2016-02-01

    We demonstrate a dynamically tunable elastic metamaterial, which employs remote magnetic force to adjust its vibration absorption properties. The 1D metamaterial is constructed from a flat aluminum beam milled with a linear array of cylindrical holes. The beam is backed by a thin elastic membrane, on which thin disk-shaped permanent magnets are mounted. When excited by a shaker, the beam motion is tracked by a Laser Doppler Vibrometer, which conducts point by point scanning of the vibrating element. Elastic waves are unable to propagate through the beam when the driving frequency excites the first elastic bending mode in the unit cell. At these frequencies, the effective mass density of the unit cell becomes negative, which induces an exponentially decaying evanescent wave. Due to the non-linear elastic properties of the membrane, the effective stiffness of the unit cell can be tuned with an external magnetic force from nearby solenoids. Measurements of the linear and cubic static stiffness terms of the membrane are in excellent agreement with experimental measurements of the bandgap shift as a function of the applied force. In this implementation, bandgap shifts by as much as 40% can be achieved with ˜30 mN of applied magnetic force. This structure has potential for extension in 2D and 3D, providing a general approach for building dynamically tunable elastic metamaterials for applications in lensing and guiding elastic waves.

  19. Elastic metamaterial beam with remotely tunable stiffness

    SciTech Connect

    Qian, Wei; Yu, Zhengyue; Wang, Xiaole; Lai, Yun; Yellen, Benjamin B.

    2016-02-07

    We demonstrate a dynamically tunable elastic metamaterial, which employs remote magnetic force to adjust its vibration absorption properties. The 1D metamaterial is constructed from a flat aluminum beam milled with a linear array of cylindrical holes. The beam is backed by a thin elastic membrane, on which thin disk-shaped permanent magnets are mounted. When excited by a shaker, the beam motion is tracked by a Laser Doppler Vibrometer, which conducts point by point scanning of the vibrating element. Elastic waves are unable to propagate through the beam when the driving frequency excites the first elastic bending mode in the unit cell. At these frequencies, the effective mass density of the unit cell becomes negative, which induces an exponentially decaying evanescent wave. Due to the non-linear elastic properties of the membrane, the effective stiffness of the unit cell can be tuned with an external magnetic force from nearby solenoids. Measurements of the linear and cubic static stiffness terms of the membrane are in excellent agreement with experimental measurements of the bandgap shift as a function of the applied force. In this implementation, bandgap shifts by as much as 40% can be achieved with ∼30 mN of applied magnetic force. This structure has potential for extension in 2D and 3D, providing a general approach for building dynamically tunable elastic metamaterials for applications in lensing and guiding elastic waves.

  20. Estimation of In vivo Cancellous Bone Elasticity

    NASA Astrophysics Data System (ADS)

    Otani, Takahiko; Mano, Isao; Tsujimoto, Toshiyuki; Yamamoto, Tadahito; Teshima, Ryota; Naka, Hiroshi

    2009-07-01

    The effect of decreasing bone density (a symptom of osteoporosis) is greater for cancellous bone than for dense cortical bone, because cancellous bone is metabolically more active. Therefore, the bone density or bone mineral density of cancellous bone is generally used to estimate the onset of osteoporosis. Elasticity or elastic constant is a fundamental mechanical parameter and is directly related to the mechanical strength of bone. Accordingly, elasticity is a preferable parameter for assessing fracture risk. A novel ultrasonic bone densitometer LD-100 has been developed to determine the mass density and elasticity of cancellous bone with a spatial resolution comparable to that of peripheral quantitative computed tomography. Bone density and bone elasticity are evaluated using ultrasonic parameters based on fast and slow waves in cancellous bone by modeling the ultrasonic wave propagation path. Elasticity is deduced from the measured bone density and the propagation speed of the fast wave. Thus, the elasticity of cancellous bone is approximately expressed by a cubic equation of bone density.

  1. Application of numerical methods to elasticity imaging.

    PubMed

    Castaneda, Benjamin; Ormachea, Juvenal; Rodríguez, Paul; Parker, Kevin J

    2013-03-01

    Elasticity imaging can be understood as the intersection of the study of biomechanical properties, imaging sciences, and physics. It was mainly motivated by the fact that pathological tissue presents an increased stiffness when compared to surrounding normal tissue. In the last two decades, research on elasticity imaging has been an international and interdisciplinary pursuit aiming to map the viscoelastic properties of tissue in order to provide clinically useful information. As a result, several modalities of elasticity imaging, mostly based on ultrasound but also on magnetic resonance imaging and optical coherence tomography, have been proposed and applied to a number of clinical applications: cancer diagnosis (prostate, breast, liver), hepatic cirrhosis, renal disease, thyroiditis, arterial plaque evaluation, wall stiffness in arteries, evaluation of thrombosis in veins, and many others. In this context, numerical methods are applied to solve forward and inverse problems implicit in the algorithms in order to estimate viscoelastic linear and nonlinear parameters, especially for quantitative elasticity imaging modalities. In this work, an introduction to elasticity imaging modalities is presented. The working principle of qualitative modalities (sonoelasticity, strain elastography, acoustic radiation force impulse) and quantitative modalities (Crawling Waves Sonoelastography, Spatially Modulated Ultrasound Radiation Force (SMURF), Supersonic Imaging) will be explained. Subsequently, the areas in which numerical methods can be applied to elasticity imaging are highlighted and discussed. Finally, we present a detailed example of applying total variation and AM-FM techniques to the estimation of elasticity.

  2. Intramuscular pressures beneath elastic and inelastic leggings

    NASA Technical Reports Server (NTRS)

    Murthy, G.; Ballard, R. E.; Breit, G. A.; Watenpaugh, D. E.; Hargens, A. R.

    1994-01-01

    Leg compression devices have been used extensively by patients to combat chronic venous insufficiency and by astronauts to counteract orthostatic intolerance following spaceflight. However, the effects of elastic and inelastic leggings on the calf muscle pump have not been compared. The purpose of this study was to compare in normal subjects the effects of elastic and inelastic compression on leg intramuscular pressure (IMP), an objective index of calf muscle pump function. IMP in soleus and tibialis anterior muscles was measured with transducer-tipped catheters. Surface compression between each legging and the skin was recorded with an air bladder. Subjects were studied under three conditions: (1) control (no legging), (2) elastic legging, and (3) inelastic legging. Pressure data were recorded for each condition during recumbency, sitting, standing, walking, and running. Elastic leggings applied significantly greater surface compression during recumbency (20 +/- 1 mm Hg, mean +/- SE) than inelastic leggings (13 +/- 2 mm Hg). During recumbency, elastic leggings produced significantly higher soleus IMP of 25 +/- 1 mm Hg and tibialis anterior IMP of 28 +/- 1 mm Hg compared to 17 +/- 1 mm Hg and 20 +/- 2 mm Hg, respectively, generated by inelastic leggings and 8 +/- 1 mm Hg and 11 +/- 1 mm Hg, respectively, without leggings. During sitting, walking, and running, however, peak IMPs generated in the muscular compartments by elastic and inelastic leggings were similar. Our results suggest that elastic leg compression applied over a long period in the recumbent posture may impede microcirculation and jeopardize tissue viability.(ABSTRACT TRUNCATED AT 250 WORDS).

  3. Hysteresis and nonlinear elasticity in rocks

    SciTech Connect

    McCall, K.R.; Guyer, R.A.

    1993-12-01

    The purpose of this paper is to describe a theory of the propagation of elastic waves in hysteretic nonlinear elastic materials, e.g., rock. In the next section, we introduce the Priesach-Mayergoyz (P-M) model [6,7] of hysteretic systems and adapt it to describe the hysteretic mesoscopic elastic units (HMEU) determining the elastic properties of a rock. We combine the P-M model with effective medium theory (EMT) [8] to find the elastic response of a rock that has experienced a specified pressure history. Next, we consider elastic wave propagation in a hysteretic nonlinear elastic system governed by a history dependent equation of state. We consider one-dimensional propagation of compressional waves. The equation of motion for the longitudinal displacement field contains the same hysteretic nonlinear interactions that characterize the equation of state. We solve the equation of motion using the Green function technique developed by McCall [9]. This solution lets us identify the qualitative features in harmonic generation that are signatures of nonlinearity and hysteresis.

  4. EDITORIAL: Photonic materials on demand Photonic materials on demand

    NASA Astrophysics Data System (ADS)

    Zheludev, Nikolay; Padilla, Willie J.; Brener, Igal

    2012-11-01

    As David Payne famously said, 'we never have a photonic material that we want...'. This has changed with the proliferation of nanotechnology. Metamaterials—artificial media structured on a sub-wavelength scale—offer a radical paradigm for the engineering of optical properties. Some remarkable advances have been possible with metamaterials. These include, for instance, negative-index media that refract light in the opposite direction from that of conventional materials, chiral materials that rotate the polarization state of light hundreds of thousands of times more strongly than natural optical crystals, and structured thin films with remarkably strong dispersion that can slow light in much the same way as resonant atomic systems with electromagnetically induced transparency. The research agenda is now shifting towards achieving tunable and switchable functionalities with metamaterials [1] where the goal is, paraphrasing Dave Payne, 'to have on demand the photonic material that we want'. The papers in this Journal of Optics special issue explore and review the different approaches to both switching and tuning of metamaterial properties through exploiting effects such as phase conjugation, intense photo-excitation and photoconductivity, the use of electro-optical effects in conductive oxides, the exploitation global quantum coherency and resonantly coupled classical resonator and quantum structures, hybridization with gain media and the manipulation with shapes and constitution of the complex metamolecules and metamaterial reliefs by design, or using MEMS actuation. References [1] Zheludev N I and Kivshar Y 2012 From metamaterials to metadevices Nature Mater.11 917

  5. Role of elasticity in stagnant lid convection

    NASA Astrophysics Data System (ADS)

    Patocka, Vojtech; Tackley, Paul; Cadek, Ondrej

    2016-04-01

    A present limitation of global thermo-chemical convection models is that they assume a purely viscous or visco-plastic flow law for solid rock, i.e. elasticity is ignored. This may not be a good assumption in the cold, outer boundary layer known as the lithosphere, where elastic deformation may be important. Elasticity in the lithosphere plays at least two roles: It changes surface topography, which changes the relationship between topography and gravity, and it alters the stress distribution in the lithosphere, which may affect dynamical behaviour such as the formation of plate boundaries and other tectonics features. In the present work we study these effects in the context of stagnant lid convection. We use StagYY (Tackley, 2008) enhanced to include elasticity through adding advected elastic stresses to the momentum equation and replacing viscosity by the "effective" one (the method described in e.g. Moresi et al., 2002). First, a test example with a cylinder rising below the lithosphere (Crameri et al., 2012) is considered in various geometries and the effect of elasticity on the resulting topography and geoid is evaluated. Both free-slip and free-surface upper boundary condition is considered. Second, comparison of stagnant lid convection models with and without elasticity is performed. It is shown that global characteristics of the convection do not change when a realistic value of shear modulus is employed and that the stress pattern in the lithosphere is very similar. The most important effect is that stresses build up gradually when elasticity is considered and thus the stress picture is more stable in the time domain in the elastic than in the viscous case. Viscoelastic lithosphere thus filters internal dynamics more effectively than a purely viscous one, responding only to features which stay stable for times comparable to its relaxation time. This effect is clearly recognizable only when free-surface upper boundary condition is considered. The role of

  6. Structural basis of spectrin elasticity

    SciTech Connect

    Shen, B.W.; Stevens, F.J.; Luthi, U.; Goldin, S.B.

    1991-10-17

    A new model of human erythrocyte {alpha}-spectrin is proposed. The secondary structure of human erythrocyte {alpha}-spectrin and its folding into a condensed structure that can convert reversibly in situ, into an elongated configuration is predicted from its deduced protein sequence. Results from conformational and amphipathicity analyses suggest that {alpha}-spectrin consists mainly of short amphipathicity helices interconnected by flexible turns and/or coils. The distribution of charges and amphipathicity of the helices can facilitate their folding into stable domains of 4 and 3 helices surrounding a hydrophobic core. The association between adjacent four- and three-helix domains further organize them into recurring seven-helix motifs that might constitute the basic structural units of the extended {alpha}-spectrin. The elongated spectrin molecule packs, in a sinusoidal fashion, through interactions between neighboring motifs into a compact structure. We suggest that the reversible extension and contraction of this sigmoidally packed structure is the molecular basis of the mechanism by which spectrin contributes to the elasticity of the red cell membrane.

  7. Elasticity and Binding of Adenovirus

    NASA Astrophysics Data System (ADS)

    Matthews, Garrett; Negishi, Atsuko; Seeger, Adam; McCarty, Doug; Taylor, Russell; Samulshi, Jude; Superfine, Richard

    1999-11-01

    Adenovirus was the first human virus found to cause the transformation of cells and is one of the more common vectors being used for the development of gene therapy. As such, much is known about the viral structure and genome; however, the events of the early infection cycle, such as binding of the virus to the cell membrane and the release of genetic material from the capsid, for this and other nonenveloped viruses, are not fully understood. With the atomic force microscope (AFM) we are able to image the virus in both air and liquids, allowing us to change the surrounding environment, varying such physiologically relevant parameters as osmolality or pH. We additionally have the ability to do manipulations on single virus particles in these environments using the nanoManipulator. The nanoManipulator is an advanced interface for AFM that allows real time three dimensional rendering of the topographical data, allows the sample surface to be non-destructively felt using a hand held stylus that responds to the information being sensed at the tip, and allows controlled modification of the surface. Using this tool we have translated single virions over various surfaces, allowing us to measure the adhesion between the capsid and these surfaces. Additionally, we are able to place the tip directly atop individual viruses and measure their elasticity under a compressive load being supplied by that tip. We can explore how this property changes as a function of the properties of the surrounding liquid.

  8. Elasticity of polymeric nanocolloidal particles

    PubMed Central

    Riest, Jonas; Athanasopoulou, Labrini; Egorov, Sergei A.; Likos, Christos N.; Ziherl, Primož

    2015-01-01

    Softness is an essential mechanical feature of macromolecular particles such as polymer-grafted nanocolloids, polyelectrolyte networks, cross-linked microgels as well as block copolymer and dendrimer micelles. Elasticity of individual particles directly controls their swelling, wetting, and adsorption behaviour, their aggregation and self-assembly as well as structural and rheological properties of suspensions. Here we use numerical simulations and self-consistent field theory to study the deformation behaviour of a single spherical polymer brush upon diametral compression. We observe a universal response, which is rationalised using scaling arguments and interpreted in terms of two coarse-grained models. At small and intermediate compressions the deformation can be accurately reproduced by modelling the brush as a liquid drop, whereas at large compressions the brush behaves as a soft ball. Applicable far beyond the pairwise-additive small-strain regime, the models may be used to describe microelasticity of nanocolloids in severe confinement including dense disordered and crystalline phases. PMID:26522242

  9. Elastic/Inelastic Measurement Project

    SciTech Connect

    Yates, Steven; Hicks, Sally; Vanhoy, Jeffrey; McEllistrem, Marcus

    2016-03-01

    The work scope involves the measurement of neutron scattering from natural sodium (23Na) and two isotopes of iron, 56Fe and 54Fe. Angular distributions, i.e., differential cross sections, of the scattered neutrons will be measured for 5 to 10 incident neutron energies per year. The work of the first year concentrates on 23Na, while the enriched iron samples are procured. Differential neutron scattering cross sections provide information to guide nuclear reaction model calculations in the low-­energy (few MeV) fast-­neutron region. This region lies just above the isolated resonance region, which in general is well studied; however, model calculations are difficult in this region because overlapping resonance structure is evident and direct nuclear reactions are becoming important. The standard optical model treatment exhibits good predictive ability for the wide-­region average cross sections but cannot treat the overlapping resonance features. In addition, models that do predict the direct reaction component must be guided by measurements to describe correctly the strength of the direct component, e.g., β2 must be known to describe the direct component of the scattering to the first excited state. Measurements of the elastic scattering differential cross sections guide the optical model calculations, while inelastic differential cross sections provide the crucial information for correctly describing the direct component. Activities occurring during the performance period are described.

  10. Capillary stretching of elastic fibers

    NASA Astrophysics Data System (ADS)

    Protiere, Suzie; Stone, Howard A.; Duprat, Camille

    2014-11-01

    Fibrous media consisting of constrained flexible fibers can be found in many engineered systems (membranes in filters, woven textile, matted paper). When such materials interact with a liquid, the presence of liquid/air interfaces induces capillary forces that deform the fibers. To model this interaction we study the behaviour of a finite volume of liquid deposited on two parallel flexible fibers clamped at both ends. A tension along the fibers is imposed and may be varied. We show that the system undergoes various morphological changes as the interfiber distance, the elasticity and the tension of the fibers are varied. For a certain range of parameters, the liquid spreads along the fibers and pulls them together, leading to the ``zipping'' of the fibers. This capillary adhesion can then be enhanced or reduced by changing the tension within the fibers. We will show that balancing stretching and capillary forces allows the prediction of this transition as well as the conditions for which detachment of the fibers occurs. These results may be used to prevent the clogging of fibrous membranes or to optimize the capture of liquids.

  11. Highly elastic conductive polymeric MEMS

    PubMed Central

    Ruhhammer, J; Zens, M; Goldschmidtboeing, F; Seifert, A; Woias, P

    2015-01-01

    Polymeric structures with integrated, functional microelectrical mechanical systems (MEMS) elements are increasingly important in various applications such as biomedical systems or wearable smart devices. These applications require highly flexible and elastic polymers with good conductivity, which can be embedded into a matrix that undergoes large deformations. Conductive polydimethylsiloxane (PDMS) is a suitable candidate but is still challenging to fabricate. Conductivity is achieved by filling a nonconductive PDMS matrix with conductive particles. In this work, we present an approach that uses new mixing techniques to fabricate conductive PDMS with different fillers such as carbon black, silver particles, and multiwalled carbon nanotubes. Additionally, the electrical properties of all three composites are examined under continuous mechanical stress. Furthermore, we present a novel, low-cost, simple three-step molding process that transfers a micro patterned silicon master into a polystyrene (PS) polytetrafluoroethylene (PTFE) replica with improved release features. This PS/PTFE mold is used for subsequent structuring of conductive PDMS with high accuracy. The non sticking characteristics enable the fabrication of delicate structures using a very soft PDMS, which is usually hard to release from conventional molds. Moreover, the process can also be applied to polyurethanes and various other material combinations. PMID:27877753

  12. Highly elastic conductive polymeric MEMS

    NASA Astrophysics Data System (ADS)

    Ruhhammer, J.; Zens, M.; Goldschmidtboeing, F.; Seifert, A.; Woias, P.

    2015-02-01

    Polymeric structures with integrated, functional microelectrical mechanical systems (MEMS) elements are increasingly important in various applications such as biomedical systems or wearable smart devices. These applications require highly flexible and elastic polymers with good conductivity, which can be embedded into a matrix that undergoes large deformations. Conductive polydimethylsiloxane (PDMS) is a suitable candidate but is still challenging to fabricate. Conductivity is achieved by filling a nonconductive PDMS matrix with conductive particles. In this work, we present an approach that uses new mixing techniques to fabricate conductive PDMS with different fillers such as carbon black, silver particles, and multiwalled carbon nanotubes. Additionally, the electrical properties of all three composites are examined under continuous mechanical stress. Furthermore, we present a novel, low-cost, simple three-step molding process that transfers a micro patterned silicon master into a polystyrene (PS) polytetrafluoroethylene (PTFE) replica with improved release features. This PS/PTFE mold is used for subsequent structuring of conductive PDMS with high accuracy. The non sticking characteristics enable the fabrication of delicate structures using a very soft PDMS, which is usually hard to release from conventional molds. Moreover, the process can also be applied to polyurethanes and various other material combinations.

  13. Elastic properties of polycrystalline dense matter

    NASA Astrophysics Data System (ADS)

    Kobyakov, D.; Pethick, C. J.

    2015-04-01

    Elastic properties of the solid regions of neutron star crusts and white dwarfs play an important role in theories of stellar oscillations. Matter in compact stars is presumably polycrystalline and, since the elastic properties of single crystals of such matter are very anisotropic, it is necessary to relate elastic properties of the polycrystal to those of a single crystal. We calculate the effective shear modulus of polycrystalline matter with randomly oriented crystallites using a self-consistent theory that has been very successful in applications to terrestrial materials and show that previous calculations overestimate the shear modulus by approximately 28 per cent.

  14. Polycrystalline gamma plutonium's elastic moduli versus temperature

    SciTech Connect

    Migliori, Albert; Betts, J; Trugman, A; Mielke, C H; Mitchell, J N; Ramos, M; Stroe, I

    2009-01-01

    Resonant ultrasound spectroscopy was used to measure the elastic properties of pure polycrystalline {sup 239}Pu in the {gamma} phase. Shear and longitudinal elastic moduli were measured simultaneously and the bulk modulus was computed from them. A smooth, linear, and large decrease of all elastic moduli with increasing temperature was observed. They calculated the Poisson ratio and found that it increases from 0.242 at 519 K to 0.252 at 571 K. These measurements on extremely well characterized pure Pu are in agreement with other reported results where overlap occurs.

  15. Deterministic Folding in Stiff Elastic Membranes

    NASA Astrophysics Data System (ADS)

    Tallinen, T.; Åström, J. A.; Timonen, J.

    2008-09-01

    Crumpled membranes have been found to be characterized by complex patterns of spatially seemingly random facets separated by narrow ridges of high elastic energy. We demonstrate by numerical simulations that compression of stiff elastic membranes with small randomness in their initial configurations leads to either random ridge configurations (high entropy) or nearly deterministic folds (low elastic energy). For folding with symmetric ridge configurations to appear in part of the crumpling processes, the crumpling rate must be slow enough. Folding stops when the thickness of the folded structure becomes important, and crumpling continues thereafter as a random process.

  16. Failure of classical elasticity in auxetic foams

    NASA Astrophysics Data System (ADS)

    Roh, J. H.; Giller, C. B.; Mott, P. H.; Roland, C. M.

    2013-04-01

    Poisson's ratio, ν, was measured for four materials, a rubbery polymer, a conventional soft foam, and two auxetic foams. We find that for the first two materials, having ν ≥ 0.2, the experimental determinations of Poisson's ratio are in good agreement with values calculated from the shear and tensile moduli using the equations of classical elasticity. However, for the two auxetic materials (ν < 0), the equations of classical elasticity give values significantly different from the measured ν. We offer an interpretation of these results based on a recently published analysis of the bounds on Poisson's ratio for classical elasticity to be applicable.

  17. Full Elasticity Tensor from Thermal Diffuse Scattering

    NASA Astrophysics Data System (ADS)

    Wehinger, Björn; Mirone, Alessandro; Krisch, Michael; Bosak, Alexeï

    2017-01-01

    We present a method for the precise determination of the full elasticity tensor from a single crystal diffraction experiment using monochromatic x rays. For the two benchmark systems calcite and magnesium oxide, we show that the measurement of thermal diffuse scattering in the proximity of Bragg reflections provides accurate values of the complete set of elastic constants. This approach allows for a reliable and model-free determination of the elastic properties and can be performed together with crystal structure investigation in the same experiment.

  18. Quantum-elastic bump on a surface

    NASA Astrophysics Data System (ADS)

    Atanasov, Victor; Dandoloff, Rossen

    2017-01-01

    We use an exact solution of the elastic membrane shape equation, representing the curvature, which will serve as a quantum potential in the quantum mechanical two dimensional Schrödinger equation for a (quasi-) particle on the surface of the membrane. Surface curvature in the quasi one-dimensional case is related to an unexpected static formation: on one hand the elastic energy has a maximum where surface curvature has a maximum and on the other hand the concentration of the expectation value to find the (quasi-) particle is again where the elastic energy is concentrated, namely where surface curvature has a maximum. This represents a particular form of a conformon.

  19. U.S. Demand for Tobacco Products in a System Framework.

    PubMed

    Zheng, Yuqing; Zhen, Chen; Dench, Daniel; Nonnemaker, James M

    2016-07-11

    This study estimated a system of demand for cigarettes, little cigars/cigarillos, large cigars, e-cigarettes, smokeless tobacco, and loose smoking tobacco using market-level scanner data for convenience stores. We found that the unconditional own-price elasticities for the six categories are -1.188, -1.428, -1.501, -2.054, -0.532, and -1.678, respectively. Several price substitute (e.g., cigarettes and e-cigarettes) and complement (e.g., cigarettes and smokeless tobacco) relationships were identified. Magazine and television advertising increased demand for e-cigarettes, and magazine advertising increased demand for smokeless tobacco and had spillover effects on demand for other tobacco products. We also reported the elasticities by U.S. census regions and market size. These results may have important policy implications, especially viewed in the context of the rise of electronic cigarettes and the potential for harm reduction if combustible tobacco users switch to non-combustible tobacco products. Copyright © 2016 John Wiley & Sons, Ltd.

  20. Demand for private health insurance in Chinese urban areas.

    PubMed

    Ying, Xiao-Hua; Hu, Teh-Wei; Ren, Jane; Chen, Wen; Xu, Ke; Huang, Jin-Hui

    2007-10-01

    Between 1993 and 2003, the proportion of urban residents without health insurance rose from 27 to 50%. The probability of outpatient visits in the previous 2 weeks dropped from 19.9 to 11.8% in urban areas between 1993 and 2003, and from 16.0 to 13.9% in rural areas. To improve risk-pooling and risk-sharing, private health insurance should play an important role in China's health insurance system. This paper estimates the demand for private health insurance in urban areas using contingent valuation methods. Individuals were asked about their willingness-to-pay (WTP) for major catastrophic disease insurance (MCDI), inpatient expenses insurance (IEI), and outpatient expenses insurance (OEI). The study was based on a household survey conducted in four small cities in China in 2004 and included 2671 respondents. More people would like to buy IEI and MCDI (48.5 and 43.0%, respectively) than OEI (24.5%). In addition, individuals would pay a higher premium for MCDI and IEI than for OEI. The price elasticities of demand for MCDI, IEI, and OEI were -0.27, -0.34, and -0.42, respectively. The determinants of enrollment in the three private health insurance programs were similar with employment status, age, education, and income.

  1. Demands of immigration among Chinese immigrant nurses.

    PubMed

    Ma, Amy X; Griffin, Mary T Quinn; Capitulo, Katie L; Fitzpatrick, Joyce J

    2010-10-01

    The purpose of this study was to identify the demands of immigration among Chinese nurses that have immigrated to the USA. The relationship between the demands of immigration and length of stay in the USA was investigated also. A descriptive correlational study design was used. A convenience sample of 128 nurses was recruited. A self-administered survey was conducted using the demands of immigration scale developed by Aroian, along with a demographic questionnaire. The results showed Chinese immigrant nurses have high demands of immigration. There were significant negative relationships between the demands of immigration and length of stay in the USA. Immigration demands decreased as length of stay increased but remained high even for those who had been in the USA for > 5 years. This information is vital to health-care agencies designing and implementing adaptation programmes targeting these demands to facilitate Chinese nurses' adaptation process.

  2. Worldwide satellite market demand forecast

    NASA Technical Reports Server (NTRS)

    Bowyer, J. M.; Frankfort, M.; Steinnagel, K. M.

    1981-01-01

    The forecast is for the years 1981 - 2000 with benchmark years at 1985, 1990 and 2000. Two typs of markets are considered for this study: Hardware (worldwide total) - satellites, earth stations and control facilities (includes replacements and spares); and non-hardware (addressable by U.S. industry) - planning, launch, turnkey systems and operations. These markets were examined for the INTELSAT System (international systems and domestic and regional systems using leased transponders) and domestic and regional systems. Forecasts were determined for six worldwide regions encompassing 185 countries using actual costs for existing equipment and engineering estimates of costs for advanced systems. Most likely (conservative growth rate estimates) and optimistic (mid range growth rate estimates) scenarios were employed for arriving at the forecasts which are presented in constant 1980 U.S. dollars. The worldwide satellite market demand forecast predicts that the market between 181 and 2000 will range from $35 to $50 billion. Approximately one-half of the world market, $16 to $20 billion, will be generated in the United States.

  3. BATMAN: MOS Spectroscopy on Demand

    NASA Astrophysics Data System (ADS)

    Molinari, E.; Zamkotsian, F.; Moschetti, M.; Spano, P.; Boschin, W.; Cosentino, R.; Ghedina, A.; González, M.; Pérez, H.; Lanzoni, P.; Ramarijaona, H.; Riva, M.; Zerbi, F.; Nicastro, L.; Valenziano, L.; Di Marcantonio, P.; Coretti, I.; Cirami, R.

    2016-10-01

    Multi-Object Spectrographs (MOS) are the major instruments for studying primary galaxies and remote and faint objects. Current object selection systems are limited and/or difficult to implement in next generation MOS for space and ground-based telescopes. A promising solution is the use of MOEMS devices such as micromirror arrays, which allow the remote control of the multi-slit configuration in real time. TNG is hosting a novelty project for real-time, on-demand MOS masks based on MOEMS programmable slits. We are developing a 2048×1080 Digital-Micromirror-Device-based (DMD) MOS instrument to be mounted on the Galileo telescope, called BATMAN. It is a two-arm instrument designed for providing in parallel imaging and spectroscopic capabilities. With a field of view of 6.8×3.6 arcmin and a plate scale of 0.2 arcsec per micromirror, this astronomical setup can be used to investigate the formation and evolution of galaxies. The wavelength range is in the visible and the spectral resolution is R=560 for a 1 arcsec object, and the two arms will have 2k × 4k CCD detectors. ROBIN, a BATMAN demonstrator, has been designed, realized and integrated. We plan to have BATMAN first light by mid-2016.

  4. Mechanics of finite cracks in dissimilar anisotropic elastic media considering interfacial elasticity

    NASA Astrophysics Data System (ADS)

    Juan, Pierre-Alexandre; Dingreville, Rémi

    2017-02-01

    Interfacial crack fields and singularities in bimaterial interfaces (i.e., grain boundaries or dissimilar materials interfaces) are considered through a general formulation for two-dimensional (2-D) anisotropic elasticity while accounting for the interfacial structure by means of an interfacial elasticity paradigm. The interfacial elasticity formulation introduces boundary conditions that are effectively equivalent to those for a weakly bounded interface. This formalism considers the 2-D crack-tip elastic fields using complex variable techniques. While the consideration of the interfacial elasticity does not affect the order of the singularity, it modifies the oscillatory effects associated with problems involving interface cracks. Constructive or destructive "interferences" are directly affected by the interface structure and its elastic response. This general formulation provides an insight on the physical significance and the obvious coupling between the interface structure and the associated mechanical fields in the vicinity of the crack tip.

  5. Mechanics of finite cracks in dissimilar anisotropic elastic media considering interfacial elasticity

    SciTech Connect

    Juan, Pierre -Alexandre; Dingreville, Remi

    2016-10-31

    Interfacial crack fields and singularities in bimaterial interfaces (i.e., grain boundaries or dissimilar materials interfaces) are considered through a general formulation for two-dimensional (2-D) anisotropic elasticity while accounting for the interfacial structure by means of an interfacial elasticity paradigm. The interfacial elasticity formulation introduces boundary conditions that are effectively equivalent to those for a weakly bounded interface. This formalism considers the 2-D crack-tip elastic fields using complex variable techniques. While the consideration of the interfacial elasticity does not affect the order of the singularity, it modifies the oscillatory effects associated with problems involving interface cracks. Constructive or destructive “interferences” are directly affected by the interface structure and its elastic response. Furthermore, this general formulation provides an insight on the physical significance and the obvious coupling between the interface structure and the associated mechanical fields in the vicinity of the crack tip.

  6. Mechanics of finite cracks in dissimilar anisotropic elastic media considering interfacial elasticity

    DOE PAGES

    Juan, Pierre -Alexandre; Dingreville, Remi

    2016-10-31

    Interfacial crack fields and singularities in bimaterial interfaces (i.e., grain boundaries or dissimilar materials interfaces) are considered through a general formulation for two-dimensional (2-D) anisotropic elasticity while accounting for the interfacial structure by means of an interfacial elasticity paradigm. The interfacial elasticity formulation introduces boundary conditions that are effectively equivalent to those for a weakly bounded interface. This formalism considers the 2-D crack-tip elastic fields using complex variable techniques. While the consideration of the interfacial elasticity does not affect the order of the singularity, it modifies the oscillatory effects associated with problems involving interface cracks. Constructive or destructive “interferences” aremore » directly affected by the interface structure and its elastic response. Furthermore, this general formulation provides an insight on the physical significance and the obvious coupling between the interface structure and the associated mechanical fields in the vicinity of the crack tip.« less

  7. Demand for waste as fuel in the swedish district heating sector: a production function approach.

    PubMed

    Furtenback, Orjan

    2009-01-01

    This paper evaluates inter-fuel substitution in the Swedish district heating industry by analyzing almost all the district heating plants in Sweden in the period 1989-2003, specifically those plants incinerating waste. A multi-output plant-specific production function is estimated using panel data methods. A procedure for weighting the elasticities of factor demand to produce a single matrix for the whole industry is introduced. The price of waste is assumed to increase in response to the energy and CO2 tax on waste-to-energy incineration that was introduced in Sweden on 1 July 2006. Analysis of the plants involved in waste incineration indicates that an increase in the net price of waste by 10% is likely to reduce the demand for waste by 4.2%, and increase the demand for bio-fuels, fossil fuels, other fuels and electricity by 5.5%, 6.0%, 6.0% and 6.0%, respectively.

  8. Dynamic response of visco-elastic plates

    NASA Astrophysics Data System (ADS)

    Kadıoǧlu, Fethi; Tekin, Gülçin

    2016-12-01

    In this study, a comprehensive analysis about the dynamic response characteristics of visco-elastic plates is given. To construct the functional in the Laplace-Carson domain for the analysis of visco-elastic plates based on the Kirchhoff hypothesis, functional analysis method is employed. By using this new energy functional in the Laplace-Carson domain, moment values that are important for engineers can be obtained directly with excellent accuracy and element equations can be written explicitly. Three-element model is considered for modelling the visco-elastic material behavior. The solutions obtained in the Laplace-Carson domain by utilizing mixed finite element formulation are transformed to the time domain using the Durbin's inverse Laplace transform technique. The proposed mixed finite element formulation is shown to be simple to implement and gives satisfactory results for dynamic response of visco-elastic plates.

  9. Measuring Moduli Of Elasticity At High Temperatures

    NASA Technical Reports Server (NTRS)

    Wolfenden, Alan

    1993-01-01

    Shorter, squatter specimens and higher frequencies used in ultrasonic measurement technique. Improved version of piezo-electric ultrasonic composite oscillator technique used to measure moduli of elasticity of solid materials at high temperatures.

  10. Dislocation core radii near elastic stability limits

    NASA Astrophysics Data System (ADS)

    Sawyer, C. A.; Morris, J. W., Jr.; Chrzan, D. C.

    2013-04-01

    Recent studies of transition metal alloys with compositions that place them near their limits of elastic stability [e.g., near the body-centered-cubic (BCC) to hexagonal-close-packed (HCP) transition] suggest interesting behavior for the dislocation cores. Specifically, the dislocation core size is predicted to diverge as the stability limit is approached. Here a simple analysis rooted in elasticity theory and the computation of ideal strength is used to analyze this divergence. This analysis indicates that dislocation core radii should diverge as the elastic limits of stability are approached in the BCC, HCP, and face-centered-cubic (FCC) structures. Moreover, external stresses and dislocation-induced stresses also increase the core radii. Density functional theory based total-energy calculations are combined with anisotropic elasticity theory to compute numerical estimates of dislocation core radii.

  11. Elastic spheres can walk on water

    PubMed Central

    Belden, Jesse; Hurd, Randy C.; Jandron, Michael A.; Bower, Allan F.; Truscott, Tadd T.

    2016-01-01

    Incited by public fascination and engineering application, water-skipping of rigid stones and spheres has received considerable study. While these objects can be coaxed to ricochet, elastic spheres demonstrate superior water-skipping ability, but little is known about the effect of large material compliance on water impact physics. Here we show that upon water impact, very compliant spheres naturally assume a disk-like geometry and dynamic orientation that are favourable for water-skipping. Experiments and numerical modelling reveal that the initial spherical shape evolves as elastic waves propagate through the material. We find that the skipping dynamics are governed by the wave propagation speed and by the ratio of material shear modulus to hydrodynamic pressure. With these insights, we explain why softer spheres skip more easily than stiffer ones. Our results advance understanding of fluid-elastic body interaction during water impact, which could benefit inflatable craft modelling and, more playfully, design of elastic aquatic toys. PMID:26842860

  12. Statistical properties of a folded elastic rod

    NASA Astrophysics Data System (ADS)

    Bayart, Elsa; Deboeuf, Stéphanie; Boué, Laurent; Corson, Francis; Boudaoud, Arezki; Adda-Bedia, Mokhtar

    2010-03-01

    A large variety of elastic structures naturally seem to be confined into environments too small to accommodate them; the geometry of folded structures span a wide range of length-scales. The elastic properties of these confined systems are further constrained by self-avoidance as well as by the dimensionality of both structures and container. To mimic crumpled paper, we devised an experimental setup to study the packing of a dimensional elastic object in 2D geometries: an elastic rod is folded at the center of a circular Hele-Shaw cell by a centripetal force. The initial configuration of the rod and the acceleration of the rotating disk allow to span different final folded configurations while the final rotation speed controls the packing intensity. Using image analysis we measure geometrical and mechanical properties of the folded configurations, focusing on length, curvature and energy distributions.

  13. Positron interactions with water–total elastic, total inelastic, and elastic differential cross section measurements

    SciTech Connect

    Tattersall, Wade; Chiari, Luca; Machacek, J. R.; Anderson, Emma; Sullivan, James P.; White, Ron D.; Brunger, M. J.; Buckman, Stephen J.; Garcia, Gustavo; Blanco, Francisco

    2014-01-28

    Utilising a high-resolution, trap-based positron beam, we have measured both elastic and inelastic scattering of positrons from water vapour. The measurements comprise differential elastic, total elastic, and total inelastic (not including positronium formation) absolute cross sections. The energy range investigated is from 1 eV to 60 eV. Comparison with theory is made with both R-Matrix and distorted wave calculations, and with our own application of the Independent Atom Model for positron interactions.

  14. Microstrain-level measurement of third-order elastic constants applying dynamic acousto-elastic testing

    NASA Astrophysics Data System (ADS)

    Renaud, Guillaume; Talmant, Maryline; Marrelec, Guillaume

    2016-10-01

    The nonlinear elasticity of solids at the microstrain level has been recently studied by applying dynamic acousto-elastic testing. It is the analog of conventional quasi-static acousto-elastic experiments but the strain-dependence (or stress-dependence) of ultrasonic wave-speed is measured with an applied strain ranging from 10-7 to 10-5 and produced by a stationary elastic wave. In conventional quasi-static acousto-elastic experiments, the strain is applied in a quasi-static manner; it exceeds 10-4 and can reach 10-2. In this work, we apply dynamic acousto-elastic testing to measure the third-order elastic constants of two isotropic materials: polymethyl methacrylate and dry Berea sandstone. The peak amplitude of the dynamic applied strain is 8 × 10-6. The method is shown to be particularly suitable for materials exhibiting large elastic nonlinearity like sandstones, since the measurement is performed in the domain of validity of the third-order hyperelastic model. In contrast, conventional quasi-static acousto-elastic experiments in such materials are often performed outside the domain of validity of the third-order hyperelastic model and the stress-dependence of the ultrasonic wave-speed must be extrapolated at zero stress, leading to approximate values of the third-order elastic constants. The uncertainty of the evaluation of the third-order elastic constants is assessed by repeating multiple times the measurements and with Monte-Carlo simulations. The obtained values of the Murnaghan third-order elastic constants are l = -73 GPa ± 9%, m = -34 GPa ± 9%, and n = -61 GPa ± 10% for polymethyl methacrylate, and l = -17 000 GPa ± 20%, m = -11 000 GPa ± 10%, and n = -30 000 GPa ± 20% for dry Berea sandstone.

  15. Positron-inert gas differential elastic scattering

    NASA Technical Reports Server (NTRS)

    Kauppila, W. E.; Smith, Steven J.; Kwan, C. K.; Stein, T. S.

    1990-01-01

    Measurements are being made in a crossed beam experiment of the relative elastic differential cross section (DCS) for 5 to 300 eV positrons scattering from inert gas atoms (He, Ne, Ar, Kr, and Xe) in the angular range from 30 to 134 deg. Results obtained at energies around the positronium (Ps) formation threshold provide evidence that Ps formation and possibly other inelastic channels have an effect on the elastic scattering channel.

  16. Elastic form factors at higher CEBAF energies

    SciTech Connect

    Petratos, G.G.

    1994-04-01

    The prospects for elastic scattering from few body systems with higher beam energies at CEBAF is presented. The deuteron and{sup 3}He elastic structure functions A(Q{sup 2}) can be measured at sufficiently high momentum transfers to study the transition between the conventional meson-nucleon and the constituent quark-gluon descriptions. Possible improvements in the proton magnetic form factor data are also presented.

  17. Elastic energy of protein-DNA chimeras

    NASA Astrophysics Data System (ADS)

    Tseng, Chiao-Yu; Wang, Andrew; Zocchi, Giovanni; Rolih, Biljana; Levine, Alex J.

    2009-12-01

    We present experimental measurements of the equilibrium elastic energy of protein-DNA chimeras, for two different sets of attachment points of the DNA “molecular spring” on the surface of the protein. Combining these with measurements of the enzyme’s activity under stress and a mechanical model of the system, we determine how the elastic energy is partitioned between the DNA and the protein. The analysis shows that the protein is mechanically stiffer than the DNA spring.

  18. Elastic properties of FeSi

    SciTech Connect

    Petrova, A. E.; Krasnorussky, V. N.; Stishov, S. M.

    2010-09-15

    Measurements of the sound velocities in a single crystal of FeSi were performed in the temperature range 4-300 K. Elastic constants C{sub 11} and C{sub 44} deviate from a quasiharmonic behavior at high temperature; on the other hand, elastic constants C{sub 12} increases anomalously in the entire temperature range, indicating a change in the electron structure of this material.

  19. A NONLINEAR MESOSCOPIC ELASTIC CLASS OF MATERIALS

    SciTech Connect

    P. JOHNSON; R. GUYER; L. OSTROVSKY

    1999-09-01

    It is becoming clear that the elastic properties of rock are shared by numerous other materials (sand, soil, some ceramics, concrete, etc.). These materials have one or more of the following properties in common strong nonlinearity, hysteresis in stress-strain relation, slow dynamics and discrete memory. Primarily, it is the material's compliance, the mesoscopic linkages between the rigid components, that give these materials their unusual elastic properties.

  20. Factor demand in Swedish manufacturing industry with special reference to the demand for energy. Instantaneous adjustment models; some results

    NASA Astrophysics Data System (ADS)

    Sjoeholm, K. R.

    1981-02-01

    The dual approach to the theory of production is used to estimate factor demand functions of the Swedish manufacturing industry. Two approximations of the cost function, the translog and the generalized Leontief models, are used. The price elasticities of the factor demand do not seem to depend on the choice of model. This is at least true as to the sign pattern and as to the inputs capital, labor, total energy and other materials. Total energy is separated into solid fuels, gasoline, fuel oil, electricity and a residual. Fuel oil and electricity are found to be substitutes by both models. Capital and energy are shown to be substitutes. This implies that Swedish industry will save more energy if the capital cost can be reduced. Both models are, in the best versions, able to detect an inappropriate variable. The assumption of perfect competition on the product market, is shown to be inadequate by both models. When this assumption is relaxed, the normal substitution pattern among the inputs is resumed.

  1. Elastic modulus of cetacean auditory ossicles.

    PubMed

    Tubelli, Andrew A; Zosuls, Aleks; Ketten, Darlene R; Mountain, David C

    2014-05-01

    In order to model the hearing capabilities of marine mammals (cetaceans), it is necessary to understand the mechanical properties, such as elastic modulus, of the middle ear bones in these species. Biologically realistic models can be used to investigate the biomechanics of hearing in cetaceans, much of which is currently unknown. In the present study, the elastic moduli of the auditory ossicles (malleus, incus, and stapes) of eight species of cetacean, two baleen whales (mysticete) and six toothed whales (odontocete), were measured using nanoindentation. The two groups of mysticete ossicles overall had lower average elastic moduli (35.2 ± 13.3 GPa and 31.6 ± 6.5 GPa) than the groups of odontocete ossicles (53.3 ± 7.2 GPa to 62.3 ± 4.7 GPa). Interior bone generally had a higher modulus than cortical bone by up to 36%. The effects of freezing and formalin-fixation on elastic modulus were also investigated, although samples were few and no clear trend could be discerned. The high elastic modulus of the ossicles and the differences in the elastic moduli between mysticetes and odontocetes are likely specializations in the bone for underwater hearing.

  2. Elastic actuator for precise force control

    DOEpatents

    Pratt, G.A.; Williamson, M.M.

    1997-07-22

    The invention provides an elastic actuator consisting of a motor and a motor drive transmission connected at an output of the motor. An elastic element is connected in series with the motor drive transmission, and this elastic element is positioned to alone support the full weight of any load connected at an output of the actuator. A single force transducer is positioned at a point between a mount for the motor and an output of the actuator. This force transducer generates a force signal, based on deflection of the elastic element, that indicates force applied by the elastic element to an output of the actuator. An active feedback force control loop is connected between the force transducer and the motor for controlling the motor. This motor control is based on the force signal to deflect the elastic element an amount that produces a desired actuator output force. The produced output force is substantially independent of load motion. The invention also provides a torsional spring consisting of a flexible structure having at least three flat sections each connected integrally with and extending radially from a central section. Each flat section extends axially along the central section from a distal end of the central section to a proximal end of the central section. 30 figs.

  3. Linear Lumbar Localized Lysis of Elastic Fibers

    PubMed Central

    Tschen, Jaime A.

    2013-01-01

    Background: The absence or loss of elastic fibers in the skin is referred to as dermal elastolysis. Purpose: This paper describes a woman with a distinctive clinical presentation of mid-dermal elastolysis characterized morphologically by multiple horizontal raised bands on the lower back. Methods: A 20-year-old Filipino woman presented with multiple asymptomatic, flesh-colored, raised, firm, linear, cord-like bands on the lumbar area of her back. There were neither similar lesions elsewhere nor a family member with this condition. Results: Microscopic examination of the raised band showed nearly complete absence of elastic fibers in the mid dermis. In contrast, a biopsy of symmetrically located normal-appearing skin showed a uniform distribution of elastic fibers throughout the dermis. Linear lumbar localized elastolysis is a descriptive designation that accurately reflects a correlation of the clinical and pathological changes of this condition. Conclusion: The clinical differential of raised horizontal cord-like bands on the lower back (without a family history of an inherited elastic fiber disorder, a prior history of trauma, or a significant change in weight or exercise habit) includes linear focal elastosis and linear lumbar localized elastolysis. Microscopic evaluation of a Verhoeff-van Gieson stained lesion specimen (which may be accompanied by a biopsy of normal-appearing skin for comparison) will readily differentiate these conditions. The former is usually characterized by increased elastic fibers, whereas the latter, as in this patient, shows a paucity or absence of elastic fibers in the mid dermis. PMID:23882313

  4. Elastic actuator for precise force control

    DOEpatents

    Pratt, Gill A.; Williamson, Matthew M.

    1997-07-22

    The invention provides an elastic actuator consisting of a motor and a motor drive transmission connected at an output of the motor. An elastic element is connected in series with the motor drive transmission, and this elastic element is positioned to alone support the full weight of any load connected at an output of the actuator. A single force transducer is positioned at a point between a mount for the motor and an output of the actuator. This force transducer generates a force signal, based on deflection of the elastic element, that indicates force applied by the elastic element to an output of the actuator. An active feedback force control loop is connected between the force transducer and the motor for controlling the motor. This motor control is based on the force signal to deflect the elastic element an amount that produces a desired actuator output force. The produced output force is substantially independent of load motion. The invention also provides a torsional spring consisting of a flexible structure having at least three flat sections each connected integrally with and extending radially from a central section. Each flat section extends axially along the central section from a distal end of the central section to a proximal end of the central section.

  5. Digital instability of a confined elastic meniscus.

    PubMed

    Biggins, John S; Saintyves, Baudouin; Wei, Zhiyan; Bouchaud, Elisabeth; Mahadevan, L

    2013-07-30

    Thin soft elastic layers serving as joints between relatively rigid bodies may function as sealants, thermal, electrical, or mechanical insulators, bearings, or adhesives. When such a joint is stressed, even though perfect adhesion is maintained, the exposed free meniscus in the thin elastic layer becomes unstable, leading to the formation of spatially periodic digits of air that invade the elastic layer, reminiscent of viscous fingering in a thin fluid layer. However, the elastic instability is reversible and rate-independent, disappearing when the joint is unstressed. We use theory, experiments, and numerical simulations to show that the transition to the digital state is sudden (first-order), the wavelength and amplitude of the fingers are proportional to the thickness of the elastic layer, and the required separation to trigger the instability is inversely proportional to the in-plane dimension of the layer. Our study reveals the energetic origin of this instability and has implications for the strength of polymeric adhesives; it also suggests a method for patterning thin films reversibly with any arrangement of localized fingers in a digital elastic memory, which we confirm experimentally.

  6. Income Elasticity Literature Review | Science Inventory | US ...

    EPA Pesticide Factsheets

    Following advice from the SAB Council, when estimating the economic value of reductions in air pollution-related mortality and morbidity risk, EPA accounts for the effect of personal income on the willingness to pay to reduce the risk of adverse health outcomes. These income growth adjustment factors are calculated using a combination of income elasticity estimates and income growth projections, both of which have remained essentially unchanged since 1999. These income elasticity estimates vary according to the severity of illness. EPA recently received advice from the SAB regarding the range of income elasticities to apply as well as the research standards to use when selecting income elasticity estimates. Following this advice, EPA consulted with a contractor to update its income elasticity and income growth projections, and generate new income growth adjustment factors. The SAB would evaluate the income elasticity estimates identified in the EPA-provided literature review, determining the extent to which these estimates are appropriate to use in human health benefits assessments.

  7. Far-field subwavelength imaging for ultrasonic elastic waves in a plate using an elastic hyperlens

    NASA Astrophysics Data System (ADS)

    Lee, Hyung Jin; Kim, Hoe Woong; Kim, Yoon Young

    2011-06-01

    Subwavelength imaging was experimentally performed for ultrasonic elastic waves by using an angularly stratified plat, an elastic plate hyperlens. It consists of alternating layers of aluminum and air, exhibiting a large contrast in elastic stiffness. A specially configured experimental setup is used to locate two sources within half the wavelength at 100 kHz. To explain the observed phenomenon, the homogenization of the elasticity coefficients of the stratified structure is employed. Because of the strong cylindrical anisotropy, an equifrequency contour becomes nearly flat along the angular wave vector so that evanescent waves involved with high angular resolution are converted to propagating waves.

  8. The impact of price and tobacco control policies on the demand for electronic nicotine delivery systems

    PubMed Central

    Huang, Jidong; Tauras, John; Chaloupka, Frank J

    2014-01-01

    Background While much is known about the demand for conventional cigarettes, little is known about the determinants of demand for electronic nicotine delivery systems (ENDS or e-cigarettes). The goal of this study is to estimate the own and cross-price elasticity of demand for e-cigarettes and to examine the impact of cigarette prices and smoke-free policies on e-cigarette sales. Methods Quarterly e-cigarette prices and sales and conventional cigarette prices from 2009 to 2012 were constructed from commercial retail store scanner data from 52 US markets, for food, drug and mass stores, and from 25 markets, for convenience stores. Fixed-effects models were used to estimate the own and cross-price elasticity of demand for e-cigarettes and associations between e-cigarette sales and cigarette prices and smoke-free policies. Results Estimated own price elasticities for disposable e-cigarettes centred around −1.2, while those for reusable e-cigarettes were approximately −1.9. Disposable e-cigarette sales were higher in markets where reusable e-cigarette prices were higher and where less of the population was covered by a comprehensive smoke-free policy. There were no consistent and statistically significant relationships between cigarette prices and e-cigarette sales. Conclusions E-cigarette sales are very responsive to own price changes. Disposable e-cigarettes appear to be substitutes for reusable e-cigarettes. Policies increasing e-cigarette retail prices, such as limiting rebates, discounts and coupons and imposing a tax on e-cigarettes, could potentially lead to significant reductions in e-cigarette sales. Differential tax policies based on product type could lead to substitution between different types of e-cigarettes. PMID:24935898

  9. Pigeons' demand and preference for specific and generalized conditioned reinforcers in a token economy.

    PubMed

    Tan, Lavinia; Hackenberg, Timothy D

    2015-11-01

    Pigeons' demand and preference for specific and generalized tokens was examined in a token economy. Pigeons could produce and exchange different colored tokens for food, for water, or for food or water. Token production was measured across three phases, which examined: (1) across-session price increases (typical demand curve method); (2) within-session price increases (progressive-ratio, PR, schedule); and (3) concurrent pairwise choices between the token types. Exponential demand curves were fitted to the response data and accounted for over 90% total variance. Demand curve parameter values, Pmax , Omax and α showed that demand was ordered in the following way: food tokens, generalized tokens, water tokens, both in Phase 1 and in Phase 3. This suggests that the preferences were predictable on the basis of elasticity and response output from the demand analysis. Pmax and Omax values failed to consistently predict breakpoints and peak response rates in the PR schedules in Phase 2, however, suggesting limits on a unitary conception of reinforcer efficacy. The patterns of generalized token production and exchange in Phase 3 suggest that the generalized tokens served as substitutes for the specific food and water tokens. Taken together, the present findings demonstrate the utility of behavioral economic concepts in the analysis of generalized reinforcement.

  10. Effects of daily morphine administration and deprivation on choice and demand for remifentanil and cocaine in rhesus monkeys.

    PubMed

    Wade-Galuska, Tammy; Galuska, Chad M; Winger, Gail

    2011-01-01

    Choice procedures have indicated that the relative reinforcing effectiveness of opioid drugs increases during opioid withdrawal. The demand curve, an absolute measure of reinforcer value, has not been applied to this question. The present study assessed whether mild morphine withdrawal would increase demand for or choice of remifentanil or cocaine. Four rhesus monkeys chose between remifentanil and cocaine during daily sessions. Demand curves for both drugs were subsequently obtained. The effects of daily injections of 3.2 mg/kg morphine on both choice and demand for these drugs was assayed 3 and 20.5 hr after each morphine injection, and then during a postmorphine period. Three hours following morphine injections, choice of remifentanil over cocaine decreased and demand for remifentanil--but not cocaine--became more elastic. During morphine withdrawal (20.5 hr postinjection), choice of remifentanil increased and remifentanil demand became more inelastic in 3 of 4 monkeys. Cocaine demand also became more inelastic during this period. Four to five weeks following the morphine regimen, demand for both drugs was more inelastic relative to the initial determination. The results suggest that both the relative and absolute reinforcing effectiveness of remifentanil decreased following morphine administration and increased during morphine withdrawal. The absolute reinforcing effectiveness of cocaine also increased during morphine withdrawal. In addition, extended exposure to drug self-administration and/or exposure to the morphine regimen produced long-term increases in demand for both drugs.

  11. Elastic Wave Propagation Mechanisms in Underwater Acoustic Environments

    DTIC Science & Technology

    2015-09-30

    Elastic wave propagation mechanisms in underwater acoustic environments Scott D. Frank Marist College Department of Mathematics Poughkeepsie...conversion from elastic propagation to acoustic propagation, and intense interface waves on underwater acoustic environments with elastic bottoms... acoustic energy in the water column. Elastic material parameters will be varied for analysis of the dissipation of water column acoustic energy

  12. Transversely isotropic elasticity imaging of cancellous bone.

    PubMed

    Shore, Spencer W; Barbone, Paul E; Oberai, Assad A; Morgan, Elise F

    2011-06-01

    To measure spatial variations in mechanical properties of biological materials, prior studies have typically performed mechanical tests on excised specimens of tissue. Less invasive measurements, however, are preferable in many applications, such as patient-specific modeling, disease diagnosis, and tracking of age- or damage-related degradation of mechanical properties. Elasticity imaging (elastography) is a nondestructive imaging method in which the distribution of elastic properties throughout a specimen can be reconstructed from measured strain or displacement fields. To date, most work in elasticity imaging has concerned incompressible, isotropic materials. This study presents an extension of elasticity imaging to three-dimensional, compressible, transversely isotropic materials. The formulation and solution of an inverse problem for an anisotropic tissue subjected to a combination of quasi-static loads is described, and an optimization and regularization strategy that indirectly obtains the solution to the inverse problem is presented. Several applications of transversely isotropic elasticity imaging to cancellous bone from the human vertebra are then considered. The feasibility of using isotropic elasticity imaging to obtain meaningful reconstructions of the distribution of material properties for vertebral cancellous bone from experiment is established. However, using simulation, it is shown that an isotropic reconstruction is not appropriate for anisotropic materials. It is further shown that the transversely isotropic method identifies a solution that predicts the measured displacements, reveals regions of low stiffness, and recovers all five elastic parameters with approximately 10% error. The recovery of a given elastic parameter is found to require the presence of its corresponding strain (e.g., a deformation that generates ɛ₁₂ is necessary to reconstruct C₁₂₁₂), and the application of regularization is shown to improve accuracy. Finally

  13. Transversely Isotropic Elasticity Imaging of Cancellous Bone

    PubMed Central

    Shore, Spencer W.; Barbone, Paul E.; Oberai, Assad A.; Morgan, Elise F.

    2012-01-01

    To measure spatial variations in mechanical properties of biological materials, prior studies have typically performed mechanical tests on excised specimens of tissue. Less invasive measurements, however, are preferable in many applications, such as patient-specific modeling, disease diagnosis, and tracking of age- or damage-related degradation of mechanical properties. Elasticity imaging (elastography) is a nondestructive imaging method in which the distribution of elastic properties throughout a specimen can be reconstructed from measured strain or displacement fields. To date, most work in elasticity imaging has concerned incompressible, isotropic materials. This study presents an extension of elasticity imaging to three-dimensional, compressible, transversely isotropic materials. The formulation and solution of an inverse problem for an anisotropic tissue subjected to a combination of quasi-static loads is described, and an optimization and regularization strategy that indirectly obtains the solution to the inverse problem is presented. Several applications of transversely isotropic elasticity imaging to cancellous bone from the human vertebra are then considered. The feasibility of using isotropic elasticity imaging to obtain meaningful reconstructions of the distribution of material properties for vertebral cancellous bone from experiment is established. However, using simulation, it is shown that an isotropic reconstruction is not appropriate for anisotropic materials. It is further shown that the transversely isotropic method identifies a solution that predicts the measured displacements, reveals regions of low stiffness, and recovers all five elastic parameters with approximately 10% error. The recovery of a given elastic parameter is found to require the presence of its corresponding strain (e.g., a deformation that generates ε12 is necessary to reconstruct C1212), and the application of regularization is shown to improve accuracy. Finally, the effects

  14. Elastic Properties of Sedimentary Rocks

    NASA Astrophysics Data System (ADS)

    Melendez Martinez, Jaime

    Sedimentary rocks are an important research topic since such rocks are associated to sources of ground water as well as oil, gas, and mineral reservoirs. In this work, elastic and physical properties of a variety of sedimentary samples that include glacial sediments, carbonates, shales, one evaporite, and one argillite from a variety of locations are investigated. Assuming vertical transverse isotropy, ultrasonic compressional- and shear-waves (at 1 MHz central frequency) were measured as a function of confining pressure on all samples with the exception of glacial samples which were tested assuming isotropy. Tensile strength tests (Brazilian test) were also carried out on selected glacial samples and, in addition, static-train measurements were conducted on shales and argillite samples. Lithological and textural features of samples were obtained through thin section techniques, scanning electron microscopy images and micro-tomography images. X-ray diffraction and X-Ray fluorescence provided the mineralogical oxides content information. Porosity, density, and pore structure were studied by using a mercury intrusion porosimeter and a helium pycnometer. The wide range of porosities of the studied samples (ranging from a minimum of 1% for shales to a maximum 45% for some glacial sediments) influence the measured velocities since high porosity sample shows an noticeable velocity increment as confining pressure increases as a consequence of closure of microcracks and pores, unlike low porosity samples where increment is quasi-lineal. Implementation of Gassmann's relation to ultrasonic velocities obtained from glacial samples has negligible impact on them when assuming water saturated samples, which suggests that state of saturation it is no so important in defining such velocities and instead they are mainly frame-controlled. On the other hand, velocities measured on carbonate and evaporite samples show that samples are at best weak anisotropic, thus the intrinsic

  15. Demand forecast model based on CRM

    NASA Astrophysics Data System (ADS)

    Cai, Yuancui; Chen, Lichao

    2006-11-01

    With interiorizing day by day management thought that regarding customer as the centre, forecasting customer demand becomes more and more important. In the demand forecast of customer relationship management, the traditional forecast methods have very great limitation because much uncertainty of the demand, these all require new modeling to meet the demands of development. In this paper, the notion is that forecasting the demand according to characteristics of the potential customer, then modeling by it. The model first depicts customer adopting uniform multiple indexes. Secondly, the model acquires characteristic customers on the basis of data warehouse and the technology of data mining. The last, there get the most similar characteristic customer by their comparing and forecast the demands of new customer by the most similar characteristic customer.

  16. The Market Demand for Air Transportation

    NASA Technical Reports Server (NTRS)

    Taneja, N.

    1972-01-01

    Although the presentation will touch upon the areas of market for air transportation, the theoretical foundations of the demand function, the demand models, and model selection and evaluation, the emphasis of the presentation will be on a qualitative description of the factors affecting the demand for air transportation. The presentation will rely heavily on the results of market surveys carried out by the Port of New York Authority, the University of Michigan, and Census of Transportation.

  17. On Dynamic Nonlinear Elasticity and Small Strain

    NASA Astrophysics Data System (ADS)

    Johnson, P. A.; Sutin, A.; Guyer, R. A.; Tencate, J. A.

    2002-12-01

    We are addressing the question of whether or not there is a threshold strain behavior where anomalous nonlinear fast dynamics (ANFD) commences in rock and other similar solids, or if the elastic nonlinearity persists to the smallest measurable values. In qualitative measures of many rock types and other materials that behave in the same manner, we have not observed a threshold; however the only careful, small strain level study conducted under controlled conditions that we are aware of is that of TenCate et al. in Berea sandstone (Phys. Rev. Lett. 85, 1020-1024 (2000)). This work indicates that in Berea sandstone, the elastic nonlinearity persists to the minimum measured strains of at least 10-8. Recently, we have begun controlled experiments in other materials that exhibit ANFD in order to see whether or not they behave as Berea sandstone does. We are employing Young's mode resonance to study resonance peak shift and amplitude variations as a function of drive level and detected strain level. In this type of experiment, the time average amplitude is recorded as the sample is driven by a continuous wave source from below to above the fundamental mode resonance. The drive level is increased, and the measurement is repeated progressively over larger and larger drive levels. Experiments are conducted at ambient pressure. Pure alumina ceramic is a material that is highly, elastically-nonlinear and nonporous, and therefore the significant influence of relative humidity on elastic nonlinear response that rock suffers is avoided. Temperature is carefully monitored. Measurements on pure alumina ceramic show that, like Berea sandstone, there is no threshold of elastic nonlinearity within our measurement capability. We are now studying other solids that exhibit ANFD including rock and mixed phase metal. These results indicate that elastic nonlinearity influences all elastic measurments on these solids including modulus and Q at ambient conditions. There appears to be no

  18. Use of a latency-based demand assessment to identify potential demands for functional analyses.

    PubMed

    Call, Nathan A; Miller, Sarah J; Mintz, Joslyn Cynkus; Mevers, Joanna Lomas; Scheithauer, Mindy C; Eshelman, Julie E; Beavers, Gracie A

    2016-12-01

    Unlike potential tangible positive reinforcers, which are typically identified for inclusion in functional analyses empirically using preference assessments, demands are most often selected arbitrarily or based on caregiver report. The present study evaluated the use of a demand assessment with 12 participants who exhibited escape-maintained problem behavior. Participants were exposed to 10 demands, with aversiveness measured by average latency to the first instance of problem behavior. In subsequent functional analyses, results of a demand condition that included the demand with the shortest latency to problem behavior resulted in identification of an escape function for 11 of the participants. In contrast, a demand condition that included the demand with the longest latency resulted in identification of an escape function for only 5 participants. The implication of these findings is that for the remaining 7 participants, selection of the demand for the functional analysis without using the results of the demand assessment could have produced a false-negative finding.

  19. Frictional contact of two rotating elastic disks

    NASA Astrophysics Data System (ADS)

    Ostrik, V. I.; Ulitko, A. F.

    2007-10-01

    We study the problem of constrained uniform rotation of two precompressed elastic disks made of different materials with friction forces in the contact region taken into account. The exact solution of the problem is obtained by the Wiener-Hopf method. An important stage in the study of rolling of elastic bodies is the Hertz theory [1] of contact interaction of elastic bodies with smoothly varying curvature in the contact region under normal compression. Friction in the contact region is assumed to be negligible. If there are tangential forces and the friction in the contact region is taken into account, then the picture of contact interaction of elastic bodies changes significantly. Although the normal contact stress distribution strictly follows the Hertz theory for bodies with identical elastic properties and apparently slightly differs from the Hertz diagram for bodies made of different materials, the presence of tangential stresses results in the splitting of the contact region into the adhesion region and the slip region. This phenomenon was first established by Reynolds [2], who experimentally discovered slip regions near points of material entry in and exit from the contact region under constrained rolling of an aluminum cylinder on a rubber base. The theoretical justification of the partial slip phenomenon in the contact region, discovered by Reynolds [2], can be found in Carter [3] and Fromm [4]. Moreover, Fromm presents a complete solution of the problem of constrained uniform rotation of two identical disks. Apparently, Fromm was the first to consider the so-called "clamped" strain and postulated that slip is absent at the point at which the disk materials enter the contact region. Ishlinskii [5, 6] gave an engineering solution of the problem on slip in the contact region under rolling friction. Considering the problem on a rigid disk rolling on an elastic half-plane, we model this problem by an infinite set of elastic vertical rods using Winkler

  20. Drivers of U.S. mineral demand

    USGS Publications Warehouse

    Sznopek, John L.

    2006-01-01

    Introduction: The word 'demand' has different meanings for different people. To some, it means their 'wants and needs,' to others it is what they consume. Yet, when considering economics, demand refers to the specific amounts of goods or services that individuals will purchase at various prices. Demand is measured over a given time period. It is determined by a number of factors including income, tastes, and the price of complementary and substitute goods. In this paper, the term consumption is used fairly synonymously with the term demand. Most mineral commodities, like iron ore, copper, zinc, and gravel, are intermediate goods, which means that they are used in the production of other goods, called final goods. Demand for intermediate goods is called derived demand because such demand is derived from the demand for final goods. When demand increases for a commodity, generally the price rises. With everything else held constant, this increases the profits for those who provide this commodity. Normally, this would increase profits of existing producers and attract new producers to the market. When demand for a commodity decreases, generally the price falls. Normally, this would cause profits to fall and, as a consequence, the least efficient firms may be forced from the industry. Demand changes for specific materials as final goods or production techniques are reengineered while maintaining or improving product performance, for example, the use of aluminum in the place of copper in long distance electrical transmission lines or plastic replacing steel in automobile bumpers. Substitution contributes to efficient material usage by utilizing cheaper or technically superior materials. In this way, it may also alleviate materials scarcity. If a material becomes relatively scarce (and thus more expensive), a more abundant (and less expensive) material generally replaces it (Wagner and others, 2003, p. 91).

  1. Polarization bandgaps and fluid-like elasticity in fully solid elastic metamaterials

    NASA Astrophysics Data System (ADS)

    Ma, Guancong; Fu, Caixing; Wang, Guanghao; Del Hougne, Philipp; Christensen, Johan; Lai, Yun; Sheng, Ping

    2016-11-01

    Elastic waves exhibit rich polarization characteristics absent in acoustic and electromagnetic waves. By designing a solid elastic metamaterial based on three-dimensional anisotropic locally resonant units, here we experimentally demonstrate polarization bandgaps together with exotic properties such as `fluid-like' elasticity. We construct elastic rods with unusual vibrational properties, which we denote as `meta-rods'. By measuring the vibrational responses under flexural, longitudinal and torsional excitations, we find that each vibration mode can be selectively suppressed. In particular, we observe in a finite frequency regime that all flexural vibrations are forbidden, whereas longitudinal vibration is allowed--a unique property of fluids. In another case, the torsional vibration can be suppressed significantly. The experimental results are well interpreted by band structure analysis, as well as effective media with indefinite mass density and negative moment of inertia. Our work opens an approach to efficiently separate and control elastic waves of different polarizations in fully solid structures.

  2. Polarization bandgaps and fluid-like elasticity in fully solid elastic metamaterials

    PubMed Central

    Ma, Guancong; Fu, Caixing; Wang, Guanghao; del Hougne, Philipp; Christensen, Johan; Lai, Yun; Sheng, Ping

    2016-01-01

    Elastic waves exhibit rich polarization characteristics absent in acoustic and electromagnetic waves. By designing a solid elastic metamaterial based on three-dimensional anisotropic locally resonant units, here we experimentally demonstrate polarization bandgaps together with exotic properties such as ‘fluid-like' elasticity. We construct elastic rods with unusual vibrational properties, which we denote as ‘meta-rods'. By measuring the vibrational responses under flexural, longitudinal and torsional excitations, we find that each vibration mode can be selectively suppressed. In particular, we observe in a finite frequency regime that all flexural vibrations are forbidden, whereas longitudinal vibration is allowed—a unique property of fluids. In another case, the torsional vibration can be suppressed significantly. The experimental results are well interpreted by band structure analysis, as well as effective media with indefinite mass density and negative moment of inertia. Our work opens an approach to efficiently separate and control elastic waves of different polarizations in fully solid structures. PMID:27869197

  3. Elastic Properties of Chimpanzee Craniofacial Cortical Bone.

    PubMed

    Gharpure, Poorva; Kontogiorgos, Elias D; Opperman, Lynne A; Ross, Callum F; Strait, David S; Smith, Amanda; Pryor, Leslie C; Wang, Qian; Dechow, Paul C

    2016-12-01

    Relatively few assessments of cranial biomechanics formally take into account variation in the material properties of cranial cortical bone. Our aim was to characterize the elastic properties of chimpanzee craniofacial cortical bone and compare these to the elastic properties of dentate human craniofacial cortical bone. From seven cranial regions, 27 cylindrical samples were harvested from each of five chimpanzee crania. Assuming orthotropy, axes of maximum stiffness in the plane of the cortical plate were derived using modified equations of Hooke's law in a Mathcad program. Consistent orientations among individuals were observed in the zygomatic arch and alveolus. The density of cortical bone showed significant regional variation (P < 0.001). The elastic moduli demonstrated significant differences between sites, and a distinct pattern where E3  > E2  > E1 . Shear moduli were significantly different among regions (P < 0.001). The pattern by which chimpanzee cranial cortical bone varies in elastic properties resembled that seen in humans, perhaps suggesting that the elastic properties of craniofacial bone in fossil hominins can be estimated with at least some degree of confidence. Anat Rec, 299:1718-1733, 2016. © 2016 Wiley Periodicals, Inc.

  4. Dynamic Elasticity Model of Resilin Biopolymers

    NASA Astrophysics Data System (ADS)

    Hu, Xiao; Duki, Solomon

    2013-03-01

    Resilin proteins are `super elastic rubbers' in the flight and jumping systems of most insects, and can extend and retract millions of times. Natural resilin exhibits high resilience (> 95%) under high-frequency conditions, and could be stretched to over 300% of its original length with a low elastic modulus of 0.1-3 MPa. However, insight into the underlying molecular mechanisms responsible for resilin elasticity remains undefined. We report on the dynamic structure transitions and functions of full length resilin from fruit fly (D. melanogaster CG15920) and its different functional domains. A dynamic computational model is proposed to explain the super elasticity and energy conversion mechanisms of resilin, providing important insight into structure-function relationships for resilins, as well as other elastomeric proteins. A strong beta-turn transition was experimentally identified in the full length resilin and its non-elastic domains (Exon III). Changes in periodic long-range order were demonstrated during this transition, induced either by thermal or mechanical inputs, to confirm the universality of proposed mechanism. Further, this model offers new options for designing protein-based biopolymers with tunable material applications.

  5. Yielding Elastic Tethers Stabilize Robust Cell Adhesion

    PubMed Central

    Whitfield, Matt J.; Luo, Jonathon P.; Thomas, Wendy E.

    2014-01-01

    Many bacteria and eukaryotic cells express adhesive proteins at the end of tethers that elongate reversibly at constant or near constant force, which we refer to as yielding elasticity. Here we address the function of yielding elastic adhesive tethers with Escherichia coli bacteria as a model for cell adhesion, using a combination of experiments and simulations. The adhesive bond kinetics and tether elasticity was modeled in the simulations with realistic biophysical models that were fit to new and previously published single molecule force spectroscopy data. The simulations were validated by comparison to experiments measuring the adhesive behavior of E. coli in flowing fluid. Analysis of the simulations demonstrated that yielding elasticity is required for the bacteria to remain bound in high and variable flow conditions, because it allows the force to be distributed evenly between multiple bonds. In contrast, strain-hardening and linear elastic tethers concentrate force on the most vulnerable bonds, which leads to failure of the entire adhesive contact. Load distribution is especially important to noncovalent receptor-ligand bonds, because they become exponentially shorter lived at higher force above a critical force, even if they form catch bonds. The advantage of yielding is likely to extend to any blood cells or pathogens adhering in flow, or to any situation where bonds are stretched unequally due to surface roughness, unequal native bond lengths, or conditions that act to unzip the bonds. PMID:25473833

  6. Continuously-variable series-elastic actuator.

    PubMed

    Mooney, Luke; Herr, Hugh

    2013-06-01

    Actuator efficiency is an important factor in the design of powered leg prostheses, orthoses, exoskeletons, and legged robots. A continuously-variable series-elastic actuator (CV-SEA) is presented as an efficient actuator for legged locomotion. The CV-SEA implements a continuously-variable transmission (CVT) between a motor and series elastic element. The CVT reduces the torque seen at the motor and allows the motor to operate in speed regimes of higher efficiency, while the series-elastic element efficiently stores and releases mechanical energy, reducing motor work requirements for actuator applications where an elastic response is sought. An energy efficient control strategy for the CV-SEA was developed using a Monte-Carlo minimization method that randomly generates transmission profiles and converges on those that minimize the electrical energy consumption of the motor. The CV-SEA is compared to a standard SEA and an infinitely variable series elastic actuator (IV-SEA). Simulations suggest that a CV-SEA will require less energy that an SEA or IV-SEA when used in a knee prosthesis during level-ground walking.

  7. Elastic Coupling in Bipedally Crawling Cells

    NASA Astrophysics Data System (ADS)

    Loosley, Alex; Tang, Jay

    2012-02-01

    Periodic shape changes during cell migration are recorded in fast moving fish epithelial keratocytes where sticking and slipping at opposite sides of the cell's broad trailing edge generate bipedal locomotion and oscillatory lateral displacement of the nucleus. We use a two-dimensional finite element model to study the mechanical coupling, adhesion forces, and cell shapes that recapitulate the dynamics of these crawling cells. The model consists of elastically coupled point-like elements representing regions of the cell: leading edge, opposite sides of the trailing edge, and the nucleus. Based on simple assumptions, such as cell symmetry and localization of each element to a specific cellular region, we determine that there are only four viable permutations of elastic couplings between these four elements. We compare the four configurations and find that centralized elastic coupling to the cell nucleus and wide aspect ratio of the shape is necessary to mechanically generate realistic bipedal shape dynamics and lateral displacement of the nucleus. We suggest one configuration that is most realistic. The dynamics of this configuration are strongly dependent on the elasticity between peripheral elements, but not on the elasticity between these elements and the nucleus.

  8. Probing hysteretic elasticity in weakly nonlinear materials

    SciTech Connect

    Johnson, Paul A; Haupert, Sylvain; Renaud, Guillaume; Riviere, Jacques; Talmant, Maryline; Laugier, Pascal

    2010-12-07

    Our work is aimed at assessing the elastic and dissipative hysteretic nonlinear parameters' repeatability (precision) using several classes of materials with weak, intermediate and high nonlinear properties. In this contribution, we describe an optimized Nonlinear Resonant Ultrasound Spectroscopy (NRUS) measuring and data processing protocol applied to small samples. The protocol is used to eliminate the effects of environmental condition changes that take place during an experiment, and that may mask the intrinsic elastic nonlinearity. As an example, in our experiments, we identified external temperature fluctuation as a primary source of material resonance frequency and elastic modulus variation. A variation of 0.1 C produced a frequency variation of 0.01 %, which is similar to the expected nonlinear frequency shift for weakly nonlinear materials. In order to eliminate environmental effects, the variation in f{sub 0} (the elastically linear resonance frequency proportional to modulus) is fit with the appropriate function, and that function is used to correct the NRUS calculation of nonlinear parameters. With our correction procedure, we measured relative resonant frequency shifts of 10{sup -5} , which are below 10{sup -4}, often considered the limit to NRUS sensitivity under common experimental conditions. Our results show that the procedure is an alternative to the stringent control of temperature often applied. Applying the approach, we report nonlinear parameters for several materials, some with very small nonclassical nonlinearity. The approach has broad application to NRUS and other Nonlinear Elastic Wave Spectroscopy approaches.

  9. Vascular elastic photoacoustic tomography in humans

    NASA Astrophysics Data System (ADS)

    Hai, Pengfei; Zhou, Yong; Liang, Jinyang; Li, Chiye; Wang, Lihong V.

    2016-03-01

    Quantification of vascular elasticity can help detect thrombosis and prevent life-threatening conditions such as acute myocardial infarction or stroke. Here, we propose vascular elastic photoacoustic tomography (VE-PAT) to measure vascular elasticity in humans. VE-PAT was developed by incorporating a linear-array-based photoacoustic computed tomography system with a customized compression stage. By measuring the deformation of blood vessels under uniaxial loading, VE-PAT was able to quantify the vascular compliance. We first demonstrated the feasibility of VE-PAT in blood vessel phantoms. In large vessel phantoms, VE-PAT detected a decrease in vascular compliance due to simulated thrombosis, which was validated by a standard compression test. In small blood vessel phantoms embedded 3 mm deep in gelatin, VE-PAT detected elasticity changes at depths that are difficult to image using other elasticity imaging techniques. We then applied VE-PAT to assess vascular compliance in a human subject and detected a decrease in vascular compliance when an occlusion occurred downstream from the measurement point, demonstrating the potential of VE-PAT in clinical applications such as detection of deep venous thrombosis.

  10. The Elastic Constants for Wrought Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Templin, R L; Hartmann, E C

    1945-01-01

    There are several constants which have been devised as numerical representations of the behavior of metals under the action of loadings which stress the metal within the range of elastic action. Some of these constants, such as Young's modulus of elasticity in tension and compression, shearing modulus of elasticity, and Poisson's ratio, are regularly used in engineering calculations. Precise tests and experience indicate that these elastic constants are practically unaffected by many of the factors which influence the other mechanical properties of materials and that a few careful determinations under properly controlled conditions are more useful and reliable than many determinations made under less favorable conditions. It is the purpose of this paper to outline the methods employed by the Aluminum Research Laboratories for the determination of some of these elastic constants, to list the values that have been determined for some of the wrought aluminum alloys, and to indicate the variations in the values that may be expected for some of the commercial products of these alloys.

  11. Soft random solids and their heterogeneous elasticity

    NASA Astrophysics Data System (ADS)

    Mao, Xiaoming; Goldbart, Paul M.; Xing, Xiangjun; Zippelius, Annette

    2009-09-01

    Spatial heterogeneity in the elastic properties of soft random solids is examined via vulcanization theory. The spatial heterogeneity in the structure of soft random solids is a result of the fluctuations locked-in at their synthesis, which also brings heterogeneity in their elastic properties. Vulcanization theory studies semimicroscopic models of random-solid-forming systems and applies replica field theory to deal with their quenched disorder and thermal fluctuations. The elastic deformations of soft random solids are argued to be described by the Goldstone sector of fluctuations contained in vulcanization theory, associated with a subtle form of spontaneous symmetry breaking that is associated with the liquid-to-random-solid transition. The resulting free energy of this Goldstone sector can be reinterpreted as arising from a phenomenological description of an elastic medium with quenched disorder. Through this comparison, we arrive at the statistics of the quenched disorder of the elasticity of soft random solids in terms of residual stress and Lamé-coefficient fields. In particular, there are large residual stresses in the equilibrium reference state, and the disorder correlators involving the residual stress are found to be long ranged and governed by a universal parameter that also gives the mean shear modulus.

  12. Soft random solids and their heterogeneous elasticity.

    PubMed

    Mao, Xiaoming; Goldbart, Paul M; Xing, Xiangjun; Zippelius, Annette

    2009-09-01

    Spatial heterogeneity in the elastic properties of soft random solids is examined via vulcanization theory. The spatial heterogeneity in the structure of soft random solids is a result of the fluctuations locked-in at their synthesis, which also brings heterogeneity in their elastic properties. Vulcanization theory studies semimicroscopic models of random-solid-forming systems and applies replica field theory to deal with their quenched disorder and thermal fluctuations. The elastic deformations of soft random solids are argued to be described by the Goldstone sector of fluctuations contained in vulcanization theory, associated with a subtle form of spontaneous symmetry breaking that is associated with the liquid-to-random-solid transition. The resulting free energy of this Goldstone sector can be reinterpreted as arising from a phenomenological description of an elastic medium with quenched disorder. Through this comparison, we arrive at the statistics of the quenched disorder of the elasticity of soft random solids in terms of residual stress and Lamé-coefficient fields. In particular, there are large residual stresses in the equilibrium reference state, and the disorder correlators involving the residual stress are found to be long ranged and governed by a universal parameter that also gives the mean shear modulus.

  13. Estimating Large-Customer Demand Response Market Potential:Integrating Price and Customer Behavior

    SciTech Connect

    Goldman, Charles; Hopper, Nicole; Bharvirkar, Ranjit; Neenan,Bernie; Cappers, Peter

    2007-06-01

    ABSTRACT=Demand response (DR) is increasingly recognized asan essential ingredient to well-functioning electricity markets. DRmarket potential studies can answer questions about the amount of DRavailable in a given area, from which market segments. Several recent DRmarket potential studies have been conducted, most adapting techniquesused to estimate energy-efficiency (EE) potential. In this scoping study,we: reviewed and categorized seven recent DR market potential studies;recommended a methodology for estimating DR market potential for large,non-residential utility customers that uses price elasticities to accountfor behavior and prices; compiled participation rates and elasticityvalues from six DR options offered to large customers in recent years,and demonstrated our recommended methodology with large customer marketpotential scenarios at an illustrative Northeastern utility. We recommendan elasticity approach for large-customer DR options that rely oncusto!

  14. The demand for sports and exercise: results from an illustrative survey.

    PubMed

    Anokye, Nana Kwame; Pokhrel, Subhash; Buxton, Martin; Fox-Rushby, Julia

    2012-06-01

    There is a paucity of empirical evidence on the extent to which price and perceived benefits affect the level of participation in sports and exercise. Using an illustrative sample of 60 adults at Brunel University, West London, we investigate the determinants of demand for sports and exercise. The data were collected through face-to-face interviews that covered indicators of sports and exercise behaviour; money/time price and perceived benefits of participation; and socio-economic/demographic details. Count, linear and probit regression models were fitted as appropriate. Seventy eight per cent of the sample participated in sports and exercise and spent an average of £27 per month and an average of 20 min travelling per occasion of sports and exercise. The demand for sport and exercise was negatively associated with time (travel or access time) and 'variable' price and positively correlated with 'fixed' price. Demand was price inelastic, except in the case of meeting the UK government's recommended level of participation, which is time price elastic (elasticity = -2.2). The implications of data from a larger nationally representative sample as well as the role of economic incentives in influencing uptake of sports and exercise are discussed.

  15. Latent factor structure of a behavioral economic cigarette demand curve in adolescent smokers.

    PubMed

    Bidwell, L Cinnamon; MacKillop, James; Murphy, James G; Tidey, Jennifer W; Colby, Suzanne M

    2012-11-01

    Behavioral economic demand curves, or quantitative representations of drug consumption across a range of prices, have been used to assess motivation for a variety of drugs. Such curves generate multiple measures of drug demand that are associated with cigarette consumption and nicotine dependence. However, little is known about the relationships among these facets of demand. The aim of the study was to quantify these relationships in adolescent smokers by using exploratory factor analysis to examine the underlying structure of the facets of nicotine incentive value generated from a demand curve measure. Participants were 138 adolescent smokers who completed a hypothetical cigarette purchase task, which assessed estimated cigarette consumption at escalating levels of price/cigarette. Demand curves and five facets of demand were generated from the measure: Elasticity (i.e., 1/α or proportionate price sensitivity); Intensity (i.e., consumption at zero price); O(max) (i.e., maximum financial expenditure on cigarettes); P(max) (i.e., price at which expenditure is maximized); and Breakpoint (i.e., the price that suppresses consumption to zero). Principal components analysis was used to examine the latent structure among the variables. The results revealed a two-factor solution, which were interpreted as "Persistence," reflecting insensitivity to escalating price, and "Amplitude," reflecting the absolute levels of consumption and price. These findings suggest a two factor structure of nicotine incentive value as measured via a demand curve. If supported, these findings have implications for understanding the relationships among individual demand indices in future behavioral economic studies and may further contribute to understanding of the nature of cigarette reinforcement.

  16. Pathological Demand Avoidance: Exploring the Behavioural Profile

    ERIC Educational Resources Information Center

    O'Nions, Elizabeth; Viding, Essi; Greven, Corina U; Ronald, Angelica; Happé, Francesca

    2014-01-01

    "Pathological Demand Avoidance" is a term increasingly used by practitioners in the United Kingdom. It was coined to describe a profile of obsessive resistance to everyday demands and requests, with a tendency to resort to "socially manipulative" behaviour, including outrageous or embarrassing acts. Pathological demand…

  17. Evaluation of the MEDLARS Demand Search Service.

    ERIC Educational Resources Information Center

    Lancaster, F.W.

    A detailed analysis was made by the National Library of Medicine of the performance of the Medical Literature and Analysis System (MEDLARS) in relation to 300 actual "demand search" requests made to the systems in 1966 and 1967. The objectives of the study were : (1) to study the demand search requirements of MEDLARS users, (2) to…

  18. Information management - Assessing the demand for information

    NASA Technical Reports Server (NTRS)

    Rogers, William H.

    1991-01-01

    Information demand is defined in terms of both information content (what information) and form (when, how, and where it is needed). Providing the information richness required for flight crews to be informed without overwhelming their information processing capabilities will require a great deal of automated intelligence. It is seen that the essence of this intelligence is comprehending and capturing the demand for information.

  19. MAJOR AGRICULTURAL MIGRANT LABOR DEMAND AREAS.

    ERIC Educational Resources Information Center

    Department of Labor, Washington, DC.

    DEPICTED ARE 12 CHARTS OF MAJOR CROP PRODUCTION CENTERS IN THE UNITED STATES WHICH DEMAND THE LABOR OF MIGRATORY FARM WORKERS THROUGHOUT THE YEAR. EACH CHART ILLUSTRATES THE AREAS OF AGRICULTURAL MIGRANT LABOR DEMAND FOR ONE MONTH OF THE YEAR. THE PURPOSE IS TO ACQUAINT THE PUBLIC WITH THE COMPLEXITY OF PLACING AND SCHEDULING MIGRATORY WORKERS…

  20. 46 CFR 169.689 - Demand loads.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Demand loads. 169.689 Section 169.689 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Machinery and Electrical Electrical Installations on Vessels of 100 Gross Tons and Over § 169.689 Demand loads....

  1. School Characteristics and the Demand for College.

    ERIC Educational Resources Information Center

    Bezmen, Trisha; Depken, Craig A., II

    1998-01-01

    Estimates demand for 772 U.S. colleges in 1994 by relating new applications to easily confirmable institutional characteristics. Demand is positively related to out-of-state tuition but inversely related to in-state tuition. Those who apply to public and private colleges are distinct subpopulations. Private-school applicants are less price- and…

  2. Supply and Demand for Education Staff.

    ERIC Educational Resources Information Center

    Illinois State Board of Education, Springfield, Dept. of Planning, Research and Evaluation.

    This report provides an overview of educator supply and demand, educator under/oversupply, projected areas of greatest demand and need, and information regarding retirement of teachers in Illinois. Major findings include the following: there appears to be a sufficient number of qualified teachers, yet there are still a number of unfilled positions…

  3. Career Technical Education and Labor Market Demand

    ERIC Educational Resources Information Center

    National Association of State Directors of Career Technical Education Consortium, 2012

    2012-01-01

    Current data indicates that Career Technical Education (CTE) graduates with high school diplomas or postsecondary skills are preparing for careers in fields that are growing or in high-demand. Matching employability skills with workforce demand has been an issue among industries across the nation. CTE provides relevant academic and technical…

  4. Teaching Aggregate Demand and Supply Models

    ERIC Educational Resources Information Center

    Wells, Graeme

    2010-01-01

    The author analyzes the inflation-targeting model that underlies recent textbook expositions of the aggregate demand-aggregate supply approach used in introductory courses in macroeconomics. He shows how numerical simulations of a model with inflation inertia can be used as a tool to help students understand adjustments in response to demand and…

  5. Faculty Supply and Demand in Education.

    ERIC Educational Resources Information Center

    Castle, Sharon; Arends, Richard I.

    2003-01-01

    Investigated current levels of faculty supply and demand at 752 American Association of Colleges for Teacher Education member institutions. Survey data indicate that demand is greater than supply, shortages are more critical in some program areas than others (e.g., early childhood and special education), the percentage of minority hires has…

  6. 46 CFR 169.689 - Demand loads.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Demand loads. 169.689 Section 169.689 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Machinery and Electrical Electrical Installations on Vessels of 100 Gross Tons and Over § 169.689 Demand loads....

  7. 46 CFR 169.689 - Demand loads.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Demand loads. 169.689 Section 169.689 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Machinery and Electrical Electrical Installations on Vessels of 100 Gross Tons and Over § 169.689 Demand loads....

  8. Three Essays Examining Household Energy Demand and Behavior

    NASA Astrophysics Data System (ADS)

    Murray, Anthony G.

    This dissertation consists of three essays examining household energy decisions and behavior. The first essay examines the adoption of energy efficient Energy Star home appliances by U.S. households. Program effectiveness requires that consumers be aware of the labeling scheme and also change their purchase decisions based on label information. The first essay examines the factors associated with consumer awareness of the Energy Star label of recently purchased major appliances and the factors associated with the choice of Energy Star labeled appliances. The findings suggest that eliminating identified gaps in Energy Star appliance adoption would result in house electricity cost savings of $164 million per year and associated carbon emission reductions of about 1.1 million metric tons per year. The second essay evaluates household energy security and the effectiveness of the Low-Income Home Energy Assistance Program (LIHEAP), the single largest energy assistance program available to poor households within the United States. Energy security is conceptually akin to the well-known concept of food security. Rasch models and household responses to energy security questions in the 2005 Residential Energy Consumption Survey are used to generate an energy insecurity index that is consistent with those found in the food insecurity literature. Participating in LIHEAP is found to significantly reduce household energy insecurity score in the index. Further, simulations show that the elimination of the energy assistance safety net currently available to households increases the number of energy insecure house- holds by over 16 percent. The third essay develops a five equation demand system to estimate household own-price, cross-price and income elasticities between electricity, natural gas, food at home, food away from home, and non-durable commodity groups. Household cross-price elasticities between energy and food commodities are of particular importance. Energy price shocks

  9. Elastic interactions synchronize beating in cardiomyocytes.

    PubMed

    Cohen, Ohad; Safran, Samuel A

    2016-07-13

    Motivated by recent experimental results, we study theoretically the synchronization of the beating phase and frequency of two nearby cardiomyocyte cells. Each cell is represented as an oscillating force dipole in an infinite, viscoelastic medium and the propagation of the elastic signal within the medium is predicted. We examine the steady-state beating of two nearby cells, and show that elastic interactions result in forces that synchronize the phase and frequency of beating in a manner that depends on their mutual orientation. The theory predicts both in-phase and anti-phase steady-state beating depending on the relative cell orientations, as well as how synchronized beating varies with substrate elasticity and the inter-cell distance. These results suggest how mechanics plays a role in cardiac efficiency, and may be relevant for the design of cardiomyocyte based micro devices and other biomedical applications.

  10. How an Elastic Body Reduces its Drag

    NASA Astrophysics Data System (ADS)

    Alben, Silas; Shelley, Michael; Zhang, Jun

    2002-11-01

    Recent studies from bio-fluid dynamics have quantified dramatic decreases in fluid drag on flexible organic structures (including tree leaves and underwater plants) as they deform in high-Reynolds-number flows. Our simple experiment considers the role of elastic bending in the steady case. Using a thin glass fiber wetted into a planar soap-film flow, we identify a transition in flow speed beyond which the fluid forces dominate the elastic response, and yield large deformations that greatly reduce drag. We construct a free-streamline model coupling fluid and elastic forces and solve it numerically. Self-similarity emerges on a shrinking length scale, resulting in a transition from the U^2 growth of rigid bodies to a U^4/3 law as the fiber exhibits large deformation. The theory gives a good rationalization of the experimental data in terms of a single non-dimensional parameter.

  11. Thermal effects in orthotropic porous elastic beams

    NASA Astrophysics Data System (ADS)

    Iaşan, D.

    2009-01-01

    This paper is concerned with the linear theory of anisotropic porous elastic bodies. The extension and bending of orthotropic porous elastic cylinders subjected to a plane temperature field is investigated. The work is motivated by the recent interest in the using of the orthotropic porous elastic solid as model for bones and various engineering materials. First, the thermoelastic deformation of inhomogeneous beams whose constitutive coefficients are independent of the axial coordinate is studied. Then, the extension and bending effects in orthotropic cylinders reinforced by longitudinal rods are investigated. The three-dimensional problem is reduced to the study of two-dimensional problems. The method is used to solve the problem of an orthotropic porous circular cylinder with a special kind of inhomogeneity.

  12. Dark matter elastic scattering through Higgs loops

    NASA Astrophysics Data System (ADS)

    Berlin, Asher; Hooper, Dan; McDermott, Samuel D.

    2015-12-01

    We consider a complete list of simplified models in which Majorana dark matter particles annihilate at tree level to h h or h Z final states and calculate the loop-induced elastic scattering cross section with nuclei in each case. Expressions for these annihilation and elastic scattering cross sections are provided and can be easily applied to a variety of UV-complete models. We identify several phenomenologically viable scenarios, including dark matter that annihilates through the s -channel exchange of a spin-zero mediator or through the t -channel exchange of a fermion. Although the elastic scattering cross sections predicted in this class of models are generally quite small, XENON1T and LZ should be sensitive to significant regions of this parameter space. Models in which the dark matter annihilates to h h or h Z can also generate a gamma-ray signal that is compatible with the excess observed from the Galactic center.

  13. Elasticity and Inverse Temperature Transition in Elastin

    SciTech Connect

    Perticaroli, Stefania; Ehlers, Georg; Jalarvo, Niina; Katsaras, John; Nickels, Jonathan D.

    2015-09-22

    Structurally, elastin is protein and biomaterial that provides elasticity and resilience to a range of tissues. This work provides insights into the elastic properties of elastin and its peculiar inverse temperature transition (ITT). These features are dependent on hydration of elastin and are driven by a similar mechanism of hydrophobic collapse to an entropically favorable state. Moreover, when using neutron scattering, we quantify the changes in the geometry of molecular motions above and below the transition temperature, showing a reduction in the displacement of water-induced motions upon hydrophobic collapse at the ITT. Finally, we measured the collective vibrations of elastin gels as a function of elongation, revealing no changes in the spectral features associated with local rigidity and secondary structure, in agreement with the entropic origin of elasticity.

  14. Elasticity and Inverse Temperature Transition in Elastin

    DOE PAGES

    Perticaroli, Stefania; Ehlers, Georg; Jalarvo, Niina; ...

    2015-09-22

    Structurally, elastin is protein and biomaterial that provides elasticity and resilience to a range of tissues. This work provides insights into the elastic properties of elastin and its peculiar inverse temperature transition (ITT). These features are dependent on hydration of elastin and are driven by a similar mechanism of hydrophobic collapse to an entropically favorable state. Moreover, when using neutron scattering, we quantify the changes in the geometry of molecular motions above and below the transition temperature, showing a reduction in the displacement of water-induced motions upon hydrophobic collapse at the ITT. Finally, we measured the collective vibrations of elastinmore » gels as a function of elongation, revealing no changes in the spectral features associated with local rigidity and secondary structure, in agreement with the entropic origin of elasticity.« less

  15. Seamless elastic boundaries for atomistic calculations

    NASA Astrophysics Data System (ADS)

    Pastewka, Lars; Sharp, Tristan A.; Robbins, Mark O.

    2012-08-01

    Modeling interfacial phenomena often requires both a detailed atomistic description of surface interactions and accurate calculations of long-range deformations in the substrate. The latter can be efficiently obtained using an elastic Green's function if substrate deformations are small. We present a general formulation for rapidly computing the Green's function for a planar surface given the interatomic interactions, and then coupling the Green's function to explicit atoms. The approach is fast, avoids ghost forces, and is not limited to nearest-neighbor interactions. The full system comprising explicit interfacial atoms and an elastic substrate is described by a single Hamiltonian and interactions in the substrate are treated exactly up to harmonic order. This concurrent multiscale coupling provides simple, seamless elastic boundary conditions for atomistic simulations where near-surface deformations occur, such as nanoindentation, contact, friction, or fracture. Applications to surface relaxation and contact are used to test and illustrate the approach.

  16. Series Elastic Actuators for legged robots

    NASA Astrophysics Data System (ADS)

    Pratt, Jerry E.; Krupp, Benjamin T.

    2004-09-01

    Series Elastic Actuators provide many benefits in force control of robots in unconstrained environments. These benefits include high force fidelity, extremely low impedance, low friction, and good force control bandwidth. Series Elastic Actuators employ a novel mechanical design architecture which goes against the common machine design principal of "stiffer is better." A compliant element is placed between the gear train and driven load to intentionally reduce the stiffness of the actuator. A position sensor measures the deflection, and the force output is accurately calculated using Hooke"s Law (F=Kx). A control loop then servos the actuator to the desired output force. The resulting actuator has inherent shock tolerance, high force fidelity and extremely low impedance. These characteristics are desirable in many applications including legged robots, exoskeletons for human performance amplification, robotic arms, haptic interfaces, and adaptive suspensions. We describe several variations of Series Elastic Actuators that have been developed using both electric and hydraulic components.

  17. Conservation integrals in couple stress elasticity

    NASA Astrophysics Data System (ADS)

    Lubarda, V. A.; Markenscoff, X.

    2000-03-01

    Noether's theorem on invariant variational principles is applied in the case of infinitesimal couple stress elasticity, thereby extending the analysis of Knowles and Sternberg (1972. On a class of conservation laws in linearized and finite elastostatics. Arch. Ration. Mech. Anal. 44, 187-211) beyond the range of classical elasticity. Two conserved integral quantities are deduced which generalize the J-integral and L-integral in the notation of Budiansky and Rice (1973: Budiansky, B. and Rice, J. R. (1973) Conservation laws and energy-release rates. J. Appl. Mech. 40, 201-203). An expression for an M-integral is also obtained, but it is demonstrated that there is no corresponding conservation law for this integral. Relationships of the derived path integrals to other similar quantities for couple stress elasticity which have appeared in the literature are discussed.

  18. Strategies for Demand Response in Commercial Buildings

    SciTech Connect

    Watson, David S.; Kiliccote, Sila; Motegi, Naoya; Piette, Mary Ann

    2006-06-20

    This paper describes strategies that can be used in commercial buildings to temporarily reduce electric load in response to electric grid emergencies in which supplies are limited or in response to high prices that would be incurred if these strategies were not employed. The demand response strategies discussed herein are based on the results of three years of automated demand response field tests in which 28 commercial facilities with an occupied area totaling over 11 million ft{sup 2} were tested. Although the demand response events in the field tests were initiated remotely and performed automatically, the strategies used could also be initiated by on-site building operators and performed manually, if desired. While energy efficiency measures can be used during normal building operations, demand response measures are transient; they are employed to produce a temporary reduction in demand. Demand response strategies achieve reductions in electric demand by temporarily reducing the level of service in facilities. Heating ventilating and air conditioning (HVAC) and lighting are the systems most commonly adjusted for demand response in commercial buildings. The goal of demand response strategies is to meet the electric shed savings targets while minimizing any negative impacts on the occupants of the buildings or the processes that they perform. Occupant complaints were minimal in the field tests. In some cases, ''reductions'' in service level actually improved occupant comfort or productivity. In other cases, permanent improvements in efficiency were discovered through the planning and implementation of ''temporary'' demand response strategies. The DR strategies that are available to a given facility are based on factors such as the type of HVAC, lighting and energy management and control systems (EMCS) installed at the site.

  19. Coordination of Energy Efficiency and Demand Response

    SciTech Connect

    Goldman, Charles; Reid, Michael; Levy, Roger; Silverstein, Alison

    2010-01-29

    This paper reviews the relationship between energy efficiency and demand response and discusses approaches and barriers to coordinating energy efficiency and demand response. The paper is intended to support the 10 implementation goals of the National Action Plan for Energy Efficiency's Vision to achieve all cost-effective energy efficiency by 2025. Improving energy efficiency in our homes, businesses, schools, governments, and industries - which consume more than 70 percent of the nation's natural gas and electricity - is one of the most constructive, cost-effective ways to address the challenges of high energy prices, energy security and independence, air pollution, and global climate change. While energy efficiency is an increasingly prominent component of efforts to supply affordable, reliable, secure, and clean electric power, demand response is becoming a valuable tool in utility and regional resource plans. The Federal Energy Regulatory Commission (FERC) estimated the contribution from existing U.S. demand response resources at about 41,000 megawatts (MW), about 5.8 percent of 2008 summer peak demand (FERC, 2008). Moreover, FERC recently estimated nationwide achievable demand response potential at 138,000 MW (14 percent of peak demand) by 2019 (FERC, 2009).2 A recent Electric Power Research Institute study estimates that 'the combination of demand response and energy efficiency programs has the potential to reduce non-coincident summer peak demand by 157 GW' by 2030, or 14-20 percent below projected levels (EPRI, 2009a). This paper supports the Action Plan's effort to coordinate energy efficiency and demand response programs to maximize value to customers. For information on the full suite of policy and programmatic options for removing barriers to energy efficiency, see the Vision for 2025 and the various other Action Plan papers and guides available at www.epa.gov/eeactionplan.

  20. Low temperature elastic behavior of rocks

    NASA Astrophysics Data System (ADS)

    Ulrich, T. J.; Darling, T. W.; McCall, K. R.; Fenn, J.

    2002-12-01

    The resonant frequencies of a material sample are directly related to the elastic constants characterizing the sample. Thus, by studying trends in resonant frequencies as a function of temperature, the elastic behavior of the sample may be inferred, and changes in the physical properties of the material may be tracked (for example, phase changes). Historically, tracking the resonant frequencies of a crystalline sample as a function of temperature is one of the most sensitive methods for identifying phase changes in the sample. We are using Resonant Ultrasound Spectroscopy (RUS) to track the resonant frequencies of rock samples at low temperatures. Our initial measurements showed unexpected behavior in a millimeter-sized sample of Berea sandstone in the temperature range from 77 K to 300 K [Ulrich and Darling, 2001], including hysteresis in the temperature dependence of the resonant frequencies, and softening rather than hardening as the temperature decreases. A second experimental apparatus has been developed to make RUS measurements on samples up to 2 cm by 3 cm by 8 cm in size, and over the temperature range 77 K - 400 K. RUS measurements using the new experimental system have been made on several rock samples, as well as several standards, and will be described in this talk. In general, the rock samples exhibit anomalous elastic behavior, consistent with the initial measurements on much smaller samples. Similar elastic phenomena, with similar activation energies, are seen in these rocks in room temperature measurements of resonant frequency versus strain [Tencate and Shankland, 1996]. Thus, low temperature measurements could provide insight into the mechanisms for the nonlinear elastic behavior of rocks and other materials. Ulrich T.J., Darling T.W., Observation of anomalous elastic behavior in rock at low temperatures. Geophys. Res. Let., Vol. 28, No. 11, pgs. 2293-2296, June 1, 2001. Tencate J.A., Shankland, T.J., Slow dynamics in the nonlinear response of

  1. Elastic-Stiffness Coefficients of Titanium Diboride

    PubMed Central

    Ledbetter, Hassel; Tanaka, Takaho

    2009-01-01

    Using resonance ultrasound spectroscopy, we measured the monocrystal elastic-stiffness coefficients, the Voigt Cij, of TiB2. With hexagonal symmetry, TiB2 exhibits five independent Cij: C11, C33, C44, C12, C13. Using Voigt-Reuss-Hill averaging, we converted these monocrystal values to quasiisotropic (polycrystal) elastic stiffnesses. Briefly, we comment on effects of voids. From the Cij, we calculated the Debye characteristic temperature, the Grüneisen parameter, and various sound velocities. Our study resolves the enormous differences between two previous reports of TiB2’s Cij. PMID:27504232

  2. Elastic model for dinucleosome structure and energy

    NASA Astrophysics Data System (ADS)

    Fatemi, Hashem; Khodabandeh, Fatemeh; Mohammad-Rafiee, Farshid

    2016-04-01

    The equilibrium structure of a dinucleosome is studied using an elastic model that takes into account the force and torque balance conditions. Using the proper boundary conditions, it is found that the conformational energy of the problem does not depend on the length of the linker DNA. In addition it is shown that the two histone octamers are almost perpendicular to each other, and the linker DNA in short lengths is almost straight. These findings could shed some light on the role of DNA elasticity in the chromatin structure.

  3. Elastic properties of suspended black phosphorus nanosheets

    SciTech Connect

    Wang, Jia-Ying; Li, Yang; Zhen, Liang; Xu, Cheng-Yan; Zhan, Zhao-Yao; Li, Tie

    2016-01-04

    The mechanical properties of black phosphorus (BP) nanosheets suspended over circular holes were measured by an atomic force microscope nanoindentation method. The continuum mechanic model was introduced to calculate the elastic modulus and pretension of BP nanosheets with thicknesses ranging from 14.3 to 34 nm. Elastic modulus of BP nanosheets declines with thickness, and the maximum value is 276 ± 32.4 GPa. Besides, the effective strain of BP ranges from 8 to 17% with a breaking strength of 25 GPa. Our results show that BP nanosheets serve as a promising candidate for flexible electronic applications.

  4. Elastic softening of zircon by radiation damage

    SciTech Connect

    Salje, Ekhard K. H.

    2006-09-25

    The bulk modulus and the shear modulus of zircon soften by ca. 50% when zircon is amorphized by radiation damage. A theoretical description of the experimental findings is presented which shows that the elastic response on a zircon ceramics with radiation damage follows Hashin-Shtrikman [J. Mech. Phys. Solids 11, 127 (1963)] behavior with very narrow bounds. The elastic response depends, in good approximation, on the square of the volume fraction f{sub a} of the amorphized regions. In a slightly coarser approximation one finds an almost linear interpolation of the bulk and the shear modulus between those of the crystalline state and those of the fully amorphous state.

  5. Analogies between elastic and capillary interfaces*

    NASA Astrophysics Data System (ADS)

    Snoeijer, Jacco H.

    2016-10-01

    In this paper we exploit some analogies between flows near capillary interfaces and near elastic interfaces. We first consider the elastohydrodynamics of a ball bearing and the motion of a gas bubble inside a thin channel. It is shown that there is a strong analogy between these two lubrication problems, and the respective scaling laws are derived side by side. Subsequently, the paper focuses on the limit where the involved elastic interfaces become extremely soft. It is shown that soft gels and elastomers, like liquids, can be shaped by their surface tension. We highlight some recent advances on this class of elastocapillary phenomena.

  6. Inhomogeneous Elastic Response of Silica Glass

    NASA Astrophysics Data System (ADS)

    Léonforte, F.; Tanguy, A.; Wittmer, J. P.; Barrat, J.-L.

    2006-08-01

    Using large scale molecular dynamics simulations we investigate the properties of the nonaffine displacement field induced by macroscopic uniaxial deformation of amorphous silica, a strong glass according to Angell’s classification. We demonstrate the existence of a length scale ξ characterizing the correlations of this field (corresponding to a volume of about 1000 atoms), and compare its structure to the one observed in a standard fragile model glass. The “boson-peak” anomaly of the density of states can be traced back in both cases to elastic inhomogeneities on wavelengths smaller than ξ where classical continuum elasticity becomes simply unapplicable.

  7. Elasticity of some mantle crystal structures. II.

    NASA Technical Reports Server (NTRS)

    Wang, H.; Simmons, G.

    1973-01-01

    The single-crystal elastic constants are determined as a function of pressure and temperature for rutile structure germanium dioxide (GeO2). The data are qualitatively similar to those of rutile TiO2 measured by Manghnani (1969). The compressibility in the c direction is less than one-half that in the a direction, the pressure derivative of the shear constant is negative, and the pressure derivative of the bulk modulus has a relatively high value of about 6.2. According to an elastic strain energy theory, the negative shear modulus derivative implies that the kinetic barrier to diffusion decreases with increasing pressure.

  8. Relativistic analysis of proton elastic scattering

    NASA Astrophysics Data System (ADS)

    El Nohy, N. A.; El-Hammamy, M. N.; Yoseph, S. I.; Abdel-Moneim, A. M.

    2015-04-01

    The Dirac equation as the relevant wave equation, is used in modified DWUCK4 program to calculate the elastic scattering cross section throughout the energy range suitable for relativistic treatment of proton elastic scattering by nuclei 40Ca, 58Ni, 90Zr and 208Pb. A good fit to the experimental data is presented. The real and imaginary potentials are well determined and behave regularly with energy. The behaviour of the real central effective potential shows the development of a "wine-bottle" shape in the transition energy region and the persistence of a small attractive potential in the nuclear surface region, even at 800 MeV.

  9. Elasticity limits structural superlubricity in large contacts

    NASA Astrophysics Data System (ADS)

    Sharp, Tristan A.; Pastewka, Lars; Robbins, Mark O.

    2016-03-01

    Geometrically imposed force cancellations lead to ultralow friction between rigid incommensurate crystalline asperities. Elastic deformations may avert this cancellation but are difficult to treat analytically in finite and three-dimensional systems. We use atomic-scale simulations to show that elasticity affects the friction only after the contact radius a exceeds a characteristic length set by the core width of interfacial dislocations bcore. As a increases past bcore, the frictional stress for both incommensurate and commensurate surfaces decreases to a constant value. This plateau corresponds to a Peierls stress that drops exponentially with increasing bcore but remains finite.

  10. Split spectrum: a multi-channel approach to elastic optical networking.

    PubMed

    Xia, Ming; Proietti, R; Dahlfort, Stefan; Yoo, S J B

    2012-12-31

    This paper introduces Split Spectrum, which enhances elastic optical networking by splitting a bulk traffic demand into multiple channels, when a single-channel transmission is prohibited by distance or spectrum availability. We performed transmission simulations to determine the maximum reach as a function of modulation format (dual polarization BPSK, QPSK, 16QAM), baud-rate (from 5 to 28 GBd), and number of ROADMs, for a Nyquist WDM super-channel with subcarrier spacing equal to 1.2 × baud-rate. Performance evaluation on two representative topologies shows that, compared to the previously proposed elastic optical networking, Split Spectrum doubles the zero-blocking load and achieves 100% higher network spectral efficiency at zero-blocking loads as a result of extended transmission distance and efficient utilization of spectrum fragments.

  11. Middleware for Processing Message Queues with Elasticity Support and Sequential Integrity of Asynchronous Message Processing

    NASA Astrophysics Data System (ADS)

    Henrique Teixeira, Eduardo; Patrícia Favacho de Araújo, Aletéia

    2015-10-01

    Elasticity in computing refers to dynamically adjusting the amount of allocated resources to process a distributed application. In order to achieve this, mechanisms are needed to avoid the phenomenon of the elasticity threshold detection moving constantly up or down. The existing work fails to deliver sequential integrity of asynchronous messages processing and the asymmetries of data distribution to achieve parallel consumption. This paper fills this gaps and proposes a middleware solution to dynamically analyze the flow of message queue, and a mechanism to increase the parallelized consumption based on the output behavior. An architecture for IOD (Increase On Demand) middleware is presented, with support for the increase and decrease of thread's to cope with the growth of message queues, using the technique of limit-based heuristics over a given period of time and grouping messages into sub-queues based on classification criteria.

  12. Estimating household water demand using revealed and contingent behaviors: Evidence from Vietnam

    NASA Astrophysics Data System (ADS)

    Cheesman, Jeremy; Bennett, Jeff; Son, Tran Vo Hung

    2008-11-01

    This article estimates the water demand of households using (1) municipal water exclusively and (2) municipal water and household well water in the capital city of Dak Lak Province in Vietnam. Household water demands are estimated using a panel data set formed by pooling household records of metered municipal water consumption and their stated preferences for water consumption contingent on hypothetical water prices. Estimates show that households using municipal water exclusively have very price inelastic demand. Households using municipal and household well water have more price elastic, but still inelastic, simultaneous water demand and treat municipal water and household well water as substitutes. Household water consumption is influenced by household water storage and supply infrastructure, income, and socioeconomic attributes. The demand estimates are used to forecast municipal water consumption by households in Buon Ma Thuot following an increase to the municipal water tariff to forecast the municipal water supply company's revenue stream following a tariff increase and to estimate the consumer surplus loss resulting from municipal water supply shortages.

  13. Using Count Data and Ordered Models in National Forest Recreation Demand Analysis

    NASA Astrophysics Data System (ADS)

    Simões, Paula; Barata, Eduardo; Cruz, Luis

    2013-11-01

    This research addresses the need to improve our knowledge on the demand for national forests for recreation and offers an in-depth data analysis supported by the complementary use of count data and ordered models. From a policy-making perspective, while count data models enable the estimation of monetary welfare measures, ordered models allow for the wider use of the database and provide a more flexible analysis of data. The main purpose of this article is to analyse the individual forest recreation demand and to derive a measure of its current use value. To allow a more complete analysis of the forest recreation demand structure the econometric approach supplements the use of count data models with ordered category models using data obtained by means of an on-site survey in the Bussaco National Forest (Portugal). Overall, both models reveal that travel cost and substitute prices are important explanatory variables, visits are a normal good and demographic variables seem to have no influence on demand. In particular, estimated price and income elasticities of demand are quite low. Accordingly, it is possible to argue that travel cost (price) in isolation may be expected to have a low impact on visitation levels.

  14. Using count data and ordered models in national forest recreation demand analysis.

    PubMed

    Simões, Paula; Barata, Eduardo; Cruz, Luis

    2013-11-01

    This research addresses the need to improve our knowledge on the demand for national forests for recreation and offers an in-depth data analysis supported by the complementary use of count data and ordered models. From a policy-making perspective, while count data models enable the estimation of monetary welfare measures, ordered models allow for the wider use of the database and provide a more flexible analysis of data. The main purpose of this article is to analyse the individual forest recreation demand and to derive a measure of its current use value. To allow a more complete analysis of the forest recreation demand structure the econometric approach supplements the use of count data models with ordered category models using data obtained by means of an on-site survey in the Bussaco National Forest (Portugal). Overall, both models reveal that travel cost and substitute prices are important explanatory variables, visits are a normal good and demographic variables seem to have no influence on demand. In particular, estimated price and income elasticities of demand are quite low. Accordingly, it is possible to argue that travel cost (price) in isolation may be expected to have a low impact on visitation levels.

  15. The Future of Food Demand: Understanding Differences in Global Economic Models

    SciTech Connect

    Valin, Hugo; Sands, Ronald; van der Mensbrugghe, Dominique; Nelson, Gerald; Ahammad, Helal; Blanc, Elodie; Bodirsky, Benjamin; Fujimori, Shinichiro; Hasegawa, Tomoko; Havlik, Petr; Heyhoe, Edwina; Kyle, G. Page; Mason d'Croz, Daniel; Paltsev, S.; Rolinski, Susanne; Tabeau, Andrzej; van Meijl, Hans; von Lampe, Martin; Willenbockel, Dirk

    2014-01-01

    Understanding the capacity of agricultural systems to feed the world population under climate change requires a good prospective vision on the future development of food demand. This paper reviews modeling approaches from ten global economic models participating to the AgMIP project, in particular the demand function chosen and the set of parameters used. We compare food demand projections at the horizon 2050 for various regions and agricultural products under harmonized scenarios. Depending on models, we find for a business as usual scenario (SSP2) an increase in food demand of 59-98% by 2050, slightly higher than FAO projection (54%). The prospective for animal calories is particularly uncertain with a range of 61-144%, whereas FAO anticipates an increase by 76%. The projections reveal more sensitive to socio-economic assumptions than to climate change conditions or bioenergy development. When considering a higher population lower economic growth world (SSP3), consumption per capita drops by 9% for crops and 18% for livestock. Various assumptions on climate change in this exercise do not lead to world calorie losses greater than 6%. Divergences across models are however notable, due to differences in demand system, income elasticities specification, and response to price change in the baseline.

  16. Effects of cost sharing on physician utilization under favourable conditions for supplier-induced demand.

    PubMed

    Van de Voorde, C; Van Doorslaer, E; Schokkaert, E

    2001-07-01

    The effects of cost sharing on the demand for ambulatory care in experimental circumstances are well understood since the Rand Health Insurance Experiment (HIE). However, in a non-experimental real-world context, supplier-induced demand of doctors might erode some of the significant negative out-of-pocket price elasticity identified in the HIE. Belgium is an interesting test case for this hypothesis because it has relatively high rates of patient cost sharing in its public health insurance system and a very high density of physicians, all remunerated fee-for-service. We have exploited the price variation generated by a substantial increase in patient co-payment rates in 1994 to estimate out-of-pocket price elasticities for three groups of users, and for three types of services using a fixed-effects model in levels and in differences. We obtain significant out-of-pocket price elasticities for the general population in the range from -0.39 to -0.28 for GP home visits, -0.16 to -0.12 for GP office visits and -0.10 for specialist visits. The estimates were generally lower and less significant for the groups of elderly and disabled. The differences we find in price responsiveness appear to be fairly robust and consistent with the HIE predictions. These results suggest that--at least in the short run--non-experimental utilization effects of cost sharing are very similar to the experimental evidence, even in a situation of favourable conditions for supplier-induced demand.

  17. Surface elasticity effect on the size-dependent elastic property of nanowires

    NASA Astrophysics Data System (ADS)

    Yao, Haiyan; Yun, Guohong; Bai, Narsu; Li, Jiangang

    2012-04-01

    A modified core-shell (MC-S) model is proposed to investigate the effect of surface elasticity on the elastic properties of nanowires under bending and tension loading modes. The continuous exponential function based on bulk elasticity is applied to the surface region of nanowires to better describe the elasticity in the surface layer. Two parameters related to the surface, namely, the inhomogeneous degree constant α˜, and the transition region of this inhomogeneous state rs (i.e., surface layer thickness), are introduced for examining the size effects of the elastic modulus of the overall nanowires. A strong size dependence of elasticity is revealed under both bending and tension loads. Furthermore, the theoretical solution for an effective Young's modulus with relevant experiments, as well as the results of a molecular statistical thermodynamics (MST) method for zinc oxide (ZnO) nanowires, and a molecular dynamics (MD) simulation for silicon (Si) nanowires, are compared. It is shown that the theoretical curves not only agree well with the experimental data, but also fit the computational results (MST or MD) approximately below 20 nm. As a result, our model can predict the behavior of surface elasticity, with respect to the lateral size of nanostructures at a relatively small scale, no matter how stiff or soft the surface of the nanomaterials.

  18. Thermodynamic stability in elastic systems: Hard spheres embedded in a finite spherical elastic solid.

    PubMed

    Solano-Altamirano, J M; Goldman, Saul

    2015-12-01

    We determined the total system elastic Helmholtz free energy, under the constraints of constant temperature and volume, for systems comprised of one or more perfectly bonded hard spherical inclusions (i.e. "hard spheres") embedded in a finite spherical elastic solid. Dirichlet boundary conditions were applied both at the surface(s) of the hard spheres, and at the outer surface of the elastic solid. The boundary conditions at the surface of the spheres were used to describe the rigid displacements of the spheres, relative to their initial location(s) in the unstressed initial state. These displacements, together with the initial positions, provided the final shape of the strained elastic solid. The boundary conditions at the outer surface of the elastic medium were used to ensure constancy of the system volume. We determined the strain and stress tensors numerically, using a method that combines the Neuber-Papkovich spherical harmonic decomposition, the Schwartz alternating method, and Least-squares for determining the spherical harmonic expansion coefficients. The total system elastic Helmholtz free energy was determined by numerically integrating the elastic Helmholtz free energy density over the volume of the elastic solid, either by a quadrature, or a Monte Carlo method, or both. Depending on the initial position of the hard sphere(s) (or equivalently, the shape of the un-deformed stress-free elastic solid), and the displacements, either stationary or non-stationary Helmholtz free energy minima were found. The non-stationary minima, which involved the hard spheres nearly in contact with one another, corresponded to lower Helmholtz free energies, than did the stationary minima, for which the hard spheres were further away from one another.

  19. ElaStic: A tool for calculating second-order elastic constants from first principles

    NASA Astrophysics Data System (ADS)

    Golesorkhtabar, Rostam; Pavone, Pasquale; Spitaler, Jürgen; Puschnig, Peter; Draxl, Claudia

    2013-08-01

    Elastic properties play a key role in materials science and technology. The elastic tensors at any order are defined by the Taylor expansion of the elastic energy or stress in terms of the applied strain. In this paper, we present ElaStic, a tool that is able to calculate the full second-order elastic stiffness tensor for any crystal structure from ab initio total-energy and/or stress calculations. This tool also provides the elastic compliances tensor and applies the Voigt and Reuss averaging procedure in order to obtain an evaluation of the bulk, shear, and Young moduli as well as the Poisson ratio of poly-crystalline samples. In a first step, the space-group is determined. Then, a set of deformation matrices is selected, and the corresponding structure files are produced. In a next step, total-energy or stress calculations for each deformed structure are performed by a chosen density-functional theory code. The computed energies/stresses are fitted as polynomial functions of the applied strain in order to get derivatives at zero strain. The knowledge of these derivatives allows for the determination of all independent components of the elastic tensor. In this context, the accuracy of the elastic constants critically depends on the polynomial fit. Therefore, we carefully study how the order of the polynomial fit and the deformation range influence the numerical derivatives, and we propose a new approach to obtain the most reliable results. We have applied ElaStic to representative materials for each crystal system, using total energies and stresses calculated with the full-potential all-electron codes exciting and WIEN2k as well as the pseudo-potential code Quantum ESPRESSO.

  20. The effect of public policies on the demand for higher education.

    PubMed

    Bishop, J

    1977-01-01

    A binomial logit model is fitted to the college attendance behavior of 27,046 male high-school juniors in 1960, divided into 20 subgroups defined by student ability and family income. Tuition, high admissions standards, travel costs, and room and board costs all have significant negative effects on attendance. The highest elasticities of demand are found to occur in the low-income strata and lower-middle ability quartile, suggesting that an efficient subsidy program should focus on these groups. Coefficients of forgone earnings and measures of the local payoff to college attendance are small but generally have the expected sign.

  1. Trends of jet fuel demand and properties

    NASA Technical Reports Server (NTRS)

    Friedman, R.

    1984-01-01

    Petroleum industry forecasts predict an increasing demand for jet fuels, a decrease in the gasoline-to-distillate (heavier fuel) demand ratio, and a greater influx of poorer quality petroleum in the next two to three decades. These projections are important for refinery product analyses. The forecasts have not been accurate, however, in predicting the recent, short term fluctuations in jet fuel and competing product demand. Changes in petroleum quality can be assessed, in part, by a review of jet fuel property inspections. Surveys covering the last 10 years show that average jet fuel freezing points, aromatic contents, and smoke points have trends toward their specification limits.

  2. Agricultural Irrigation Demand Response Estimation Tool

    SciTech Connect

    Olsen, Daniel

    2014-02-01

    This program is used to model the energy demand of agricultural irrigation pumps, used to maintain soil moisture levels in irrigated fields. This modeling is accomplished using historical data from evapotranspirationmeasuring weather stations (from the California Irrigation Management Information System) as well as irrigation system characteristics for the field(s) to be modeled. The modelled energy demand is used to estimate the achievable demand response (DR) potential of the field(s), for use in assessing the value of the DR for the utility company. The program can accept input data with varying degrees of rigor, and estimate the uncertainty of the output accordingly.

  3. On-demand therapy for hereditary angioedema.

    PubMed

    Bernstein, Jonathan A

    2013-11-01

    Consensus guidelines on hereditary angioedema (HAE) recommend that all patients have access to on-demand treatment of acute attacks. A recent patientcentric guideline recommended that at least 2 on-demand therapies be available because patients often have heterogeneous responses to different medications. Self-administration of therapeutic agents, or administration under supervision by a health care provider in the home setting, is the preferred treatment approach. Future studies are needed to show the benefits of acute on-demand therapies at improving quality of life and reducing morbidity and mortality in patients with HAE.

  4. Autonomous Demand Response for Primary Frequency Regulation

    SciTech Connect

    Donnelly, Matt; Trudnowski, Daniel J.; Mattix, S.; Dagle, Jeffery E.

    2012-02-28

    The research documented within this report examines the use of autonomous demand response to provide primary frequency response in an interconnected power grid. The work builds on previous studies in several key areas: it uses a large realistic model (i.e., the interconnection of the western United States and Canada); it establishes a set of metrics that can be used to assess the effectiveness of autonomous demand response; and it independently adjusts various parameters associated with using autonomous demand response to assess effectiveness and to examine possible threats or vulnerabilities associated with the technology.

  5. Membrane elastic properties and cell function.

    PubMed

    Pontes, Bruno; Ayala, Yareni; Fonseca, Anna Carolina C; Romão, Luciana F; Amaral, Racκele F; Salgado, Leonardo T; Lima, Flavia R; Farina, Marcos; Viana, Nathan B; Moura-Neto, Vivaldo; Nussenzveig, H Moysés

    2013-01-01

    Recent studies indicate that the cell membrane, interacting with its attached cytoskeleton, is an important regulator of cell function, exerting and responding to forces. We investigate this relationship by looking for connections between cell membrane elastic properties, especially surface tension and bending modulus, and cell function. Those properties are measured by pulling tethers from the cell membrane with optical tweezers. Their values are determined for all major cell types of the central nervous system, as well as for macrophage. Astrocytes and glioblastoma cells, which are considerably more dynamic than neurons, have substantially larger surface tensions. Resting microglia, which continually scan their environment through motility and protrusions, have the highest elastic constants, with values similar to those for resting macrophage. For both microglia and macrophage, we find a sharp softening of bending modulus between their resting and activated forms, which is very advantageous for their acquisition of phagocytic functions upon activation. We also determine the elastic constants of pure cell membrane, with no attached cytoskeleton. For all cell types, the presence of F-actin within tethers, contrary to conventional wisdom, is confirmed. Our findings suggest the existence of a close connection between membrane elastic constants and cell function.

  6. Matrix elasticity directs stem cell lineage specification

    NASA Astrophysics Data System (ADS)

    Discher, Dennis

    2010-03-01

    Adhesion of stem cells - like most cells - is not just a membrane phenomenon. Most tissue cells need to adhere to a ``solid'' for viability, and over the last decade it has become increasingly clear that the physical ``elasticity'' of that solid is literally ``felt'' by cells. Here we show that Mesenchymal Stem Cells (MSCs) specify lineage and commit to phenotypes with extreme sensitivity to the elasticity typical of tissues [1]. In serum only media, soft matrices that mimic brain appear neurogenic, stiffer matrices that mimic muscle are myogenic, and comparatively rigid matrices that mimic collagenous bone prove osteogenic. Inhibition of nonmuscle myosin II activity blocks all elasticity directed lineage specification, which indicates that the cytoskeleton pulls on matrix through adhesive attachments. Results have significant implications for `therapeutic' stem cells and have motivated development of a proteomic-scale method to identify mechano-responsive protein structures [2] as well as deeper physical studies of matrix physics [3] and growth factor pathways [4]. [4pt] [1] A. Engler, et al. Matrix elasticity directs stem cell lineage specification. Cell (2006).[0pt] [2] C.P. Johnson, et al. Forced unfolding of proteins within cells. Science (2007).[0pt] [3] A.E.X. Brown, et al. Multiscale mechanics of fibrin polymer: Gel stretching with protein unfolding and loss of water. Science (2009).[0pt] [4] D.E. Discher, et al. Growth factors, matrices, and forces combine and control stem cells. Science (2009).

  7. Resonant ultrasound spectroscopy for elastic constant measurements

    SciTech Connect

    Dixon, R.D.; Migliori, A.; Roe, L.H.

    1993-12-31

    All objects exhibit vibrational resonances when mechanically excited. These resonant frequencies are determined by density, geometry, and elastic moduli. Resonant ultrasound spectroscopy (RUS) takes advantage of the known relationship between the parameters. In particular, for a freely suspended object, with three of the four parameters (vibrational spectra, density, geometry, or elastic moduli) known the remaining one can be calculated. From a materials characterization standpoint it is straight-forward to measure density and geometry but less so to measure all the elastic moduli. It has recently become possible to quickly and accurately measure vibrational spectra, and using code written at Los Alamos, calculate all the elastic moduli simultaneously. This is done to an accuracy of better than one percent for compression and 0.1 percent for shear. RUS provides rapid acquisition of materials information here-to-fore obtainable only with difficulty. It will greatly facilitate the use of real materials properties in models and thus make possible more realistic modeling results. The technique is sensitive to phase changes and microstructure. This offers a change to input real data into microstructure and phase change models. It will also enable measurement of moduli at locations in and about a weld thus providing information for a validating coupled thermomechanical calculations.

  8. A Simple Geometry of Income Elasticities.

    ERIC Educational Resources Information Center

    Heavey, Jerome F.

    1994-01-01

    Contends that, although most economics students are acquainted with the graphical analysis of the income and substitution effects of a price change, they often fail to appreciate that the same graphs provide information on the income elasticities of the two goods. Illustrates the proof of this concept using mathematical formulae and five graphic…

  9. Elastic module of superhard rhenium diboride

    SciTech Connect

    Koehler, Michael R.; Keppens, Veerle; Sales, Brian C; Jin, Rongying; Mandrus, David

    2009-01-01

    The elastic moduli of polycrystalline rhenium diboride are measured as a function of temperature between 5 and 325 K. The room temperature results show that ReB{sub 2} has very high values for both the bulk and shear modulus, confirming the incompressible and superhard nature of this material. With decreasing temperature, the moduli increase, with a hint of softening below 50 K.

  10. Shielding of elastic nonstationary waves by interfaces

    NASA Astrophysics Data System (ADS)

    Gulyaev, V. I.; Lugovoi, P. Z.; Zayets, Yu. A.

    2012-07-01

    The ray method is used to solve the problem of the propagation of discontinuous (weak shock) waves in inhomogeneous elastic media. A procedure for drawing the fronts of reflected and refracted waves at interfaces and calculating their intensities is proposed. The effect of shielding discontinuous waves by one or two interfaces is studied. The cases of slipping and non-slipping contact are examined

  11. Membrane Elastic Properties and Cell Function

    PubMed Central

    Pontes, Bruno; Ayala, Yareni; Fonseca, Anna Carolina C.; Romão, Luciana F.; Amaral, Racκele F.; Salgado, Leonardo T.; Lima, Flavia R.; Farina, Marcos; Viana, Nathan B.; Moura-Neto, Vivaldo; Nussenzveig, H. Moysés

    2013-01-01

    Recent studies indicate that the cell membrane, interacting with its attached cytoskeleton, is an important regulator of cell function, exerting and responding to forces. We investigate this relationship by looking for connections between cell membrane elastic properties, especially surface tension and bending modulus, and cell function. Those properties are measured by pulling tethers from the cell membrane with optical tweezers. Their values are determined for all major cell types of the central nervous system, as well as for macrophage. Astrocytes and glioblastoma cells, which are considerably more dynamic than neurons, have substantially larger surface tensions. Resting microglia, which continually scan their environment through motility and protrusions, have the highest elastic constants, with values similar to those for resting macrophage. For both microglia and macrophage, we find a sharp softening of bending modulus between their resting and activated forms, which is very advantageous for their acquisition of phagocytic functions upon activation. We also determine the elastic constants of pure cell membrane, with no attached cytoskeleton. For all cell types, the presence of F-actin within tethers, contrary to conventional wisdom, is confirmed. Our findings suggest the existence of a close connection between membrane elastic constants and cell function. PMID:23844071

  12. 3D elastic control for mobile devices.

    PubMed

    Hachet, Martin; Pouderoux, Joachim; Guitton, Pascal

    2008-01-01

    To increase the input space of mobile devices, the authors developed a proof-of-concept 3D elastic controller that easily adapts to mobile devices. This embedded device improves the completion of high-level interaction tasks such as visualization of large documents and navigation in 3D environments. It also opens new directions for tomorrow's mobile applications.

  13. 21 CFR 880.5075 - Elastic bandage.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Elastic bandage. 880.5075 Section 880.5075 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL HOSPITAL AND PERSONAL USE DEVICES General Hospital and Personal Use Therapeutic...

  14. Elastic proton-proton scattering at RHIC

    SciTech Connect

    Yip, K.

    2011-09-03

    Here we describe elastic proton+proton (p+p) scattering measurements at RHIC in p+p collisions with a special optics run of {beta}* {approx} 21 m at STAR, at the center-of-mass energy {radical}s = 200 GeV during the last week of the RHIC 2009 run. We present preliminary results of single and double spin asymmetries.

  15. Bending rate damping in elastic systems

    NASA Technical Reports Server (NTRS)

    Banks, H. T.; Wang, Y.; Fabiano, R. H.

    1989-01-01

    Preliminary results of an investigation of the bending rate damping model for elastic structures are presented. A model for which the internal damping term is physically plausible and which can accomodate cantilevered boundary conditions is discussed. The model formulation and mathematical foundations are given, and numerical results are discussed.

  16. Nonaffine rubber elasticity for stiff polymer networks.

    PubMed

    Heussinger, Claus; Schaefer, Boris; Frey, Erwin

    2007-09-01

    We present a theory for the elasticity of cross-linked stiff polymer networks. Stiff polymers, unlike their flexible counterparts, are highly anisotropic elastic objects. Similar to mechanical beams, stiff polymers easily deform in bending, while they are much stiffer with respect to tensile forces ("stretching"). Unlike in previous approaches, where network elasticity is derived from the stretching mode, our theory properly accounts for the soft bending response. A self-consistent effective medium approach is used to calculate the macroscopic elastic moduli starting from a microscopic characterization of the deformation field in terms of "floppy modes"-low-energy bending excitations that retain a high degree of nonaffinity. The length scale characterizing the emergent nonaffinity is given by the "fiber length" lf, defined as the scale over which the polymers remain straight. The calculated scaling properties for the shear modulus are in excellent agreement with the results of recent simulations obtained in two-dimensional model networks. Furthermore, our theory can be applied to rationalize bulk rheological data in reconstituted actin networks.

  17. Water droplet impact on elastic superhydrophobic surfaces

    PubMed Central

    Weisensee, Patricia B.; Tian, Junjiao; Miljkovic, Nenad; King, William P.

    2016-01-01

    Water droplet impact on surfaces is a ubiquitous phenomenon in nature and industry, where the time of contact between droplet and surface influences the transfer of mass, momentum and energy. To manipulate and reduce the contact time of impacting droplets, previous publications report tailoring of surface microstructures that influence the droplet - surface interface. Here we show that surface elasticity also affects droplet impact, where a droplet impacting an elastic superhydrophobic surface can lead to a two-fold reduction in contact time compared to equivalent rigid surfaces. Using high speed imaging, we investigated the impact dynamics on elastic nanostructured superhydrophobic substrates having membrane and cantilever designs with stiffness 0.5–7630 N/m. Upon impact, the droplet excites the substrate to oscillate, while during liquid retraction, the substrate imparts vertical momentum back to the droplet with a springboard effect, causing early droplet lift-off with reduced contact time. Through detailed experimental and theoretical analysis, we show that this novel springboarding phenomenon is achieved for a specific range of Weber numbers (We >40) and droplet Froude numbers during spreading (Fr >1). The observation of the substrate elasticity-mediated droplet springboard effect provides new insight into droplet impact physics. PMID:27461899

  18. Oblique and Head-On Elastic Collisions

    ERIC Educational Resources Information Center

    Ng, Chiu-king

    2008-01-01

    When a moving ball collides elastically with an identical, initially stationary ball, the incident ball will either come to rest (head-on collision; see Fig. 1) or will acquire a velocity that is perpendicular to that acquired by the target ball (oblique collision; see Fig. 2). These two possible outcomes are related in an interesting way, which…

  19. Poor impulse control predicts inelastic demand for nicotine but not alcohol in rats.

    PubMed

    Diergaarde, Leontien; van Mourik, Yvar; Pattij, Tommy; Schoffelmeer, Anton N M; De Vries, Taco J

    2012-05-01

    Tobacco and alcohol dependence are characterized by continued use despite deleterious health, social and occupational consequences, implying that addicted individuals pay a high price for their use. In behavioral economic terms, such persistent consumption despite increased costs can be conceptualized as inelastic demand. Recent animal studies demonstrated that high-impulsive individuals are more willing to work for nicotine or cocaine infusions than their low-impulsive counterparts, indicating that this trait might be causally related to inelastic drug demand. By employing progressive ratio schedules of reinforcement combined with a behavioral economics approach of analysis, we determined whether trait impulsivity is associated with an insensitivity of nicotine or alcohol consumption to price increments. Rats were trained on a delayed discounting task, measuring impulsive choice. Hereafter, high- and low-impulsive rats were selected and trained to nose poke for intravenous nicotine or oral alcohol. Upon stable self-administration on a continuous reinforcement schedule, the price (i.e. response requirement) was increased. Demand curves, depicting the relationship between price and consumption, were produced using Hursh's exponential demand equation. Similar to human observations, nicotine and alcohol consumption in rats fitted this equation, thereby demonstrating the validity of our model. Moreover, high-impulsive rats displayed inelastic nicotine demand, as their nicotine consumption was less sensitive to price increments as compared with that in low-impulsive rats. Impulsive choice was not related to differences in alcohol demand elasticity. Our model seems well suited for studying nicotine and alcohol demand in rats and, as such, might contribute to our understanding of tobacco and alcohol dependence.

  20. 7 CFR 981.21 - Trade demand.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Trade demand. 981.21 Section 981.21 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... distribution worldwide....

  1. 7 CFR 981.21 - Trade demand.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Trade demand. 981.21 Section 981.21 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... distribution worldwide....

  2. 7 CFR 981.21 - Trade demand.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Trade demand. 981.21 Section 981.21 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... distribution worldwide....

  3. 7 CFR 981.21 - Trade demand.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Trade demand. 981.21 Section 981.21 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... distribution worldwide....

  4. Demand Response and Energy Storage Integration Study

    SciTech Connect

    Ma, Ookie; Cheung, Kerry

    2016-03-01

    Demand response and energy storage resources present potentially important sources of bulk power system services that can aid in integrating variable renewable generation. While renewable integration studies have evaluated many of the challenges associated with deploying large amounts of variable wind and solar generation technologies, integration analyses have not yet fully incorporated demand response and energy storage resources. This report represents an initial effort in analyzing the potential integration value of demand response and energy storage, focusing on the western United States. It evaluates two major aspects of increased deployment of demand response and energy storage: (1) Their operational value in providing bulk power system services and (2) Market and regulatory issues, including potential barriers to deployment.

  5. Teacher Demand and Supply in Western Canada.

    ERIC Educational Resources Information Center

    Kapuscinski, B. Phyllis; Haug, F. M.

    1982-01-01

    The article reviews the current status of teacher supply and demand, examines needs that have been identified, and draws implications for teacher education. The focus of the needs assessment is on one province: Saskatchewan. (AH)

  6. Electronic Eye: Streaming Video On-Demand.

    ERIC Educational Resources Information Center

    Meulen, Kathleen

    2002-01-01

    Discusses the use of on-demand streaming video in school libraries. Explains how streaming works, considers advantages and technical issues, and describes products from three companies that are pioneering streaming in the educational video market. (LRW)

  7. Global Energy: Supply, Demand, Consequences, Opportunities

    SciTech Connect

    Majumdar, Arun

    2008-08-14

    July 29, 2008 Berkeley Lab lecture: Arun Majumdar, Director of the Environmental Energy Technologies Division, discusses current and future projections of economic growth, population, and global energy demand and supply, and explores the implications of these trends for the environment.

  8. A historical analysis of natural gas demand

    NASA Astrophysics Data System (ADS)

    Dalbec, Nathan Richard

    This thesis analyzes demand in the US energy market for natural gas, oil, and coal over the period of 1918-2013 and examines their price relationship over the period of 2007-2013. Diagnostic tests for time series were used; Augmented Dickey-Fuller, Kwiatkowski-Phillips-Schmidt-Shin, Johansen cointegration, Granger Causality and weak exogeneity tests. Directed acyclic graphs were used as a complimentary test for endogeneity. Due to the varied results in determining endogeneity, a seemingly unrelated regression model was used which assumes all right hand side variables in the three demand equations were exogenous. A number of factors were significant in determining demand for natural gas including its own price, lagged demand, a number of structural break dummies, and trend, while oil indicate some substitutability with natural gas. An error correction model was used to examine the price relationships. Natural gas price was found not to have a significant cointegrating vector.

  9. Global Energy: Supply, Demand, Consequences, Opportunities

    ScienceCinema

    Majumdar, Arun

    2016-07-12

    July 29, 2008 Berkeley Lab lecture: Arun Majumdar, Director of the Environmental Energy Technologies Division, discusses current and future projections of economic growth, population, and global energy demand and supply, and explores the implications of these trends for the environment.

  10. Hawaiian Electric Company Demand Response Roadmap Project

    SciTech Connect

    Levy, Roger; Kiliccote, Sila

    2013-01-12

    The objective of this project was to develop a “roadmap” to guide the Hawaiian Electric Company (HECO) demand response (DR) planning and implementation in support of the Hawaii Clean Energy Initiative (HCEI) 70% clean energy goal by 2030.

  11. Climate policy implications for agricultural water demand

    SciTech Connect

    Chaturvedi, Vaibhav; Hejazi, Mohamad I.; Edmonds, James A.; Clarke, Leon E.; Kyle, G. Page; Davies, Evan; Wise, Marshall A.; Calvin, Katherine V.

    2013-03-01

    Energy, water and land are scarce resources, critical to humans. Developments in each affect the availability and cost of the others, and consequently human prosperity. Measures to limit greenhouse gas concentrations will inevitably exact dramatic changes on energy and land systems and in turn alter the character, magnitude and geographic distribution of human claims on water resources. We employ the Global Change Assessment Model (GCAM), an integrated assessment model to explore the interactions of energy, land and water systems in the context of alternative policies to limit climate change to three alternative levels: 2.5 Wm-2 (445 ppm CO2-e), 3.5 Wm-2 (535 ppm CO2-e) and 4.5 Wm-2 (645 ppm CO2-e). We explore the effects of two alternative land-use emissions mitigation policy options—one which taxes terrestrial carbon emissions equally with fossil fuel and industrial emissions, and an alternative which only taxes fossil fuel and industrial emissions but places no penalty on land-use change emissions. We find that increasing populations and economic growth could be anticipated to almost triple demand for water for agricultural systems across the century even in the absence of climate policy. In general policies to mitigate climate change increase agricultural demands for water still further, though the largest changes occur in the second half of the century, under both policy regimes. The two policies examined profoundly affected both the sources and magnitudes of the increase in irrigation water demands. The largest increases in agricultural irrigation water demand occurred in scenarios where only fossil fuel emissions were priced (but not land-use change emission) and were primarily driven by rapid expansion in bioenergy production. In these scenarios water demands were large relative to present-day total available water, calling into question whether it would be physically possible to produce the associated biomass energy. We explored the potential of improved

  12. Singular invariant integrals for elastic bodies with thin elastic inclusions and cracks

    NASA Astrophysics Data System (ADS)

    Khludnev, A. M.; Shcherbakov, V. V.

    2016-12-01

    Equilibrium problems for an elastic body with partially delaminated thin elastic inclusions are considered. The inclusions are modeled within the framework of the Euler-Bernoulli and Timoshenko models of elastic beams. The presence of delamination means the existence of a crack between the inclusion and the elastic matrix. Displacements of the opposite crack faces are constrained with nonpenetration conditions. Formulas of the Griffith type giving the first derivatives of energy functionals with respect to the crack length are established. It is shown that the formulas for the derivatives admit representation in the form of invariant integrals independent of the smooth closed curve surrounding the crack tip. The obtained invariant integrals consist of the sum of regular and singular parts and are analogues of the classical Eshelby-Cherepanov-Rice J-integral.

  13. Properties of elastic percolating networks in isotropic media with arbitrary elastic constants

    NASA Astrophysics Data System (ADS)

    Pla, O.; Garcia-Molina, R.; Guinea, F.; Louis, E.

    1990-06-01

    The properties of diluted elastic media in two dimensions are investigated in an isotropic system in which the ratio between the two Lamé coefficients can be varied. Changes in the ratio between the continuum elastic constants induce significant variations in the behavior of the system away from the threshold for percolation, but not in the properties near the percolation transition. We discuss the results in both cases and their relevance to the definition of the universal properties of diluted elastic networks. It is shown that many features of interest, like the bulk modulus at intermediate concentrations of voids and the backbone, are very dependent on the microscopic details of the model, and not only on its macroscopic behavior. Thus, elastic percolation does not seem to have the same degree of universality as scalar percolation.

  14. Climate elasticity of streamflow revisited - an elasticity index based on long-term hydrometeorological records

    NASA Astrophysics Data System (ADS)

    Andréassian, Vazken; Coron, Laurent; Lerat, Julien; Le Moine, Nicolas

    2016-11-01

    We present a new method to derive the empirical (i.e., data-based) elasticity of streamflow to precipitation and potential evaporation. This method, which uses long-term hydrometeorological records, is tested on a set of 519 French catchments. We compare a total of five different ways to compute elasticity: the reference method first proposed by Sankarasubramanian et al. (2001) and four alternatives differing in the type of regression model chosen (OLS or GLS, univariate or bivariate). We show that the bivariate GLS and OLS regressions provide the most robust solution, because they account for the co-variation of precipitation and potential evaporation anomalies. We also compare empirical elasticity estimates with theoretical estimates derived analytically from the Turc-Mezentsev formula. Empirical elasticity offers a powerful means to test the extrapolation capacity of those hydrological models that are to be used to predict the impact of climatic changes.

  15. Ethanol Demand in United States Gasoline Production

    SciTech Connect

    Hadder, G.R.

    1998-11-24

    The Oak Ridge National Laboratory (OWL) Refinery Yield Model (RYM) has been used to estimate the demand for ethanol in U.S. gasoline production in year 2010. Study cases examine ethanol demand with variations in world oil price, cost of competing oxygenate, ethanol value, and gasoline specifications. For combined-regions outside California summer ethanol demand is dominated by conventional gasoline (CG) because the premised share of reformulated gasoline (RFG) production is relatively low and because CG offers greater flexibility for blending high vapor pressure components like ethanol. Vapor pressure advantages disappear for winter CG, but total ethanol used in winter RFG remains low because of the low RFG production share. In California, relatively less ethanol is used in CG because the RFG production share is very high. During the winter in California, there is a significant increase in use of ethanol in RFG, as ethanol displaces lower-vapor-pressure ethers. Estimated U.S. ethanol demand is a function of the refiner value of ethanol. For example, ethanol demand for reference conditions in year 2010 is 2 billion gallons per year (BGY) at a refiner value of $1.00 per gallon (1996 dollars), and 9 BGY at a refiner value of $0.60 per gallon. Ethanol demand could be increased with higher oil prices, or by changes in gasoline specifications for oxygen content, sulfur content, emissions of volatile organic compounds (VOCS), and octane numbers.

  16. Demand for Self-Employed Health Insurance

    PubMed Central

    Emamgholipour, Sara; Arab, Mohammad; Ebrahimzadeh, Javad

    2016-01-01

    Objective: Health insurance provides financial support for health care expenditures. There are two types of health insurance: compulsory and voluntary. Voluntary health insurance can be divided into two categories: self-employed and supplementary. In this study, the main factors that affect the demand for self-employed health insurance in Iran were determined. Materials and Methods: In this cross-sectional study, data were derived from the 2013 Household Income and Expenditure Survey from the Statistical Center of Iran. Then, a logistic regression model was designed to determine the factors influencing health insurance demand. Results: The age, income, and education level of the head of the household directly correlated with the demand for self-employed health insurance. There was no significant relationship between the demand for health insurance and the gender or marital status of the head of the household. In addition, there were no significant relationships between occupation or house ownership and the demand for health insurance in rural households. Conclusion: To promote voluntary health insurance, it is helpful to identify effective factors that stimulate the health insurance demand. PMID:28149140

  17. Plate-type elastic metamaterials for low-frequency broadband elastic wave attenuation.

    PubMed

    Li, Yinggang; Zhu, Ling; Chen, Tianning

    2017-01-01

    In this paper, we numerically and experimentally demonstrate the low-frequency broadband elastic wave attenuation and vibration suppression by using plate-type elastic metamaterial, which is constituted of periodic double-sides stepped resonators deposited on a two-dimensional phononic plate with steel matrix. The dispersion relations, the power transmission spectra, and the displacement fields of the eigenmodes are calculated by using the finite element method. In contrast to the typical phononic plates consisting of periodic stepped resonators deposited on a homogeneous steel plate, the proposed elastic metamaterial can yield large band gap in the low-frequency range, resulting in the low-frequency broadband elastic wave attenuation. The formation mechanisms of the band gap as well as the effects of material and geometrical parameters on the band gap are further explored numerically. Numerical results show that, the formation mechanism of opening the low-frequency band gap is attributed to the coupling between the local resonant Lamb modes of two-dimensional phononic plate and the resonant modes of the stepped resonators. The band gap can be significantly modulated by the material and geometrical parameters. The properties of broadband gaps of the proposed subwavelength scale elastic metamaterials can potentially be applied to vibration and noise reduction in the audio regime as well as broadband elastic wave confinement and modulation in ultrasonic region.

  18. Elastic Bottom Propagation Mechanisms Investigated by Parabolic Equation Methods

    DTIC Science & Technology

    2013-09-30

    layered elastic bottom and an intervening seamount . Range-dependence associated with the seamount begins 15 km from the source. Acoustic wave energy...interacts with the elastic layers. Channeling of elastic energy in the top elastic layer appears on the left side of the seamount and continues over...bottom on the right side of the seamount , in particular at ranges greater than 65 km. Wavenumber spectra for a depth of 2550 m obtained from

  19. Cell wall elasticity: I. A critique of the bulk elastic modulus approach and an analysis using polymer elastic principles

    NASA Technical Reports Server (NTRS)

    Wu, H. I.; Spence, R. D.; Sharpe, P. J.; Goeschl, J. D.

    1985-01-01

    The traditional bulk elastic modulus approach to plant cell pressure-volume relations is inconsistent with its definition. The relationship between the bulk modulus and Young's modulus that forms the basis of their usual application to cell pressure-volume properties is demonstrated to be physically meaningless. The bulk modulus describes stress/strain relations of solid, homogeneous bodies undergoing small deformations, whereas the plant cell is best described as a thin-shelled, fluid-filled structure with a polymer base. Because cell walls possess a polymer structure, an alternative method of mechanical analysis is presented using polymer elasticity principles. This initial study presents the groundwork of polymer mechanics as would be applied to cell walls and discusses how the matrix and microfibrillar network induce nonlinear stress/strain relationships in the cell wall in response to turgor pressure. In subsequent studies, these concepts will be expanded to include anisotropic expansion as regulated by the microfibrillar network.

  20. Cell wall elasticity: I. A critique of the bulk elastic modulus approach and an analysis using polymer elastic principles.

    PubMed

    Wu, H I; Spence, R D; Sharpe, P J; Goeschl, J D

    1985-11-01

    The traditional bulk elastic modulus approach to plant cell pressure-volume relations is inconsistent with its definition. The relationship between the bulk modulus and Young's modulus that forms the basis of their usual application to cell pressure-volume properties is demonstrated to be physically meaningless. The bulk modulus describes stress/strain relations of solid, homogeneous bodies undergoing small deformations, whereas the plant cell is best described as a thin-shelled, fluid-filled structure with a polymer base. Because cell walls possess a polymer structure, an alternative method of mechanical analysis is presented using polymer elasticity principles. This initial study presents the groundwork of polymer mechanics as would be applied to cell walls and discusses how the matrix and microfibrillar network induce nonlinear stress/strain relationships in the cell wall in response to turgor pressure. In subsequent studies, these concepts will be expanded to include anisotropic expansion as regulated by the microfibrillar network.

  1. Elastic Properties of Plasticine, Silly Putty, and Tennis Strings

    ERIC Educational Resources Information Center

    Cross, Rod

    2012-01-01

    How would a physicist describe the elastic properties of an apple or a banana? Physics students and teachers are familiar with the elastic properties of metal springs, but are likely to be less familiar with the elastic properties of other common materials. The behavior of a metal spring is commonly examined in the laboratory by adding masses to…

  2. Discrete and Continuum Elastic Properties of Interfaces.

    NASA Astrophysics Data System (ADS)

    Alber, Elliott Solomon

    The microstructure of defects in solids, e.g. interfaces, is heterogeneous and, consequently, so are the elastic properties. The complete anisotropic fourth-order tensors of both the discrete and the effective elastic moduli are defined in the interfacial region. To examine the meaning of discrete elastic constants, (i) a piecewise-continuous medium is considered where individual phases occupy the Voronoi polyhedra and have the elastic moduli associated with individual atoms, and (ii) the relationship between natural vibrations of the discrete systems and continuum waves is explored. Questions of local energy changes and stability are addressed in terms of continuum properties of the moduli, particularly positive definiteness and strong ellipticity. Comparisons between the atomistic results (exact effective moduli) and those for the continuum analog (bounds) establish the validity of the definition of elastic properties for heterogeneous structures at atomic scales and lead to criteria to assess the stability of a given microstructure. Homogenization of interfacial properties gives heterogeneous transition zone (or interphase) model. Interface phenomena in macrosystems (composites) and microsystems (grain boundaries) is explained by inner layer conditions between homogeneous bulk regions. Dynamical membrane and spring models of the imperfect interfaces are shown to be limiting models (similar to Reuss and Voigt bounding approximations in multiphase composite mechanics) for asymptotic expansions of stress and strain fields, respectively. Asymptotic expansion of both fields (in terms of small parameter h -thickness of the layer) produces mixed-type, exact approximation of the first order in h. Derived models of imperfect interface are used for investigation of interface waves in anisotropic bicrystals and for comparison with corresponding acoustical modes in phonon spectra. Localized interface waves are explained as general inhomogeneous plane waves in subsonic

  3. Discrete and continuum elastic properties of interfaces

    NASA Astrophysics Data System (ADS)

    Alber, Elliott Solomon

    1993-06-01

    The microstructure of defects in solids, e.g. interfaces, is heterogeneous and, consequently, so are the elastic properties. The complete anisotropic fourth-order tensors of both the discrete and the effective elastic moduli are defined in the interfacial region. To examine the meaning of discrete elastic constants, (1) a piecewise-continuous medium is considered where individual phases occupy the Voronoi polyhedra and have the elastic moduli associated with individual atoms, and (2) the relationship between natural vibrations of the discrete systems and continuum waves is explored. Questions of local energy changes and stability are addressed in terms of continuum properties of the moduli, particularly positive definiteness and strong ellipticity. Comparisons between the atomistic results (exact effective moduli) and those for the continuum analog (bounds) establish the validity of the definition of elastic properties for heterogeneous structures at atomic scales and lead to criteria to assess the stability of a given microstructure. Homogenization of interfacial properties gives heterogeneous transition zone (or interphase) model. Interface phenomena in macrosystems (composites) and microsystems (grain boundaries) is explained by inner layer conditions between homogeneous bulk regions. Dynamical membrane and spring models of the imperfect interfaces are shown to be limiting models (similar to Reuss and Voigt bounding approximations in multiphase composite mechanics) for asymptotic expansions of stress and strain fields, respectively. Asymptotic expansion of both fields (in terms of small parameter h-thickness of the layer) produces mixed-type, exact approximation of the first order in h. Derived models of imperfect interface are used for investigation of interface waves in anisotropic bicrystals and for comparison with corresponding acoustical modes in phonon spectra. Localized interface waves are explained as general inhomogeneous plane waves in subsonic

  4. Elasticity and structure of mantle pyroxenes

    NASA Astrophysics Data System (ADS)

    Bass, J. D.; Zhang, J. S.; Sang, L.; Reynard, B.; Montagnac, G.; Dera, P. K.

    2012-12-01

    The elastic properties of both natural orthoenstatite and natural diopside have been determined at high pressures to over 14 GPa at room temperature by Brillouin spectroscopy. Single crystals of Fe-bearing orthoenstatite from San Carlos, AZ were used in one part of the study. The sound velocity data display a pronounced change in elastic character upon cold compression to above 12 GPa. There is an abrupt change in velocity anisotropy above that pressure. Single-crystal X-ray structure refinements, performed at the GSECARS beamline, Sector 13 of the APS, demonstrate that orthoenstatite transforms to a new high-pressure phase with space group P21/c (HPCEN2), with the transition pressure bracketed to be between about 10-14 GPa (JS Zhang et al., 2012). No evidence of a structure with C2/c space group was observed. Raman spectroscopy was used to explore the compositional dependence of the transition pressure and structure of the high-pressure phase. Single crystals of nearly pure Mg end-member OPX, a high-alumina sample, and an Fe-rich sample were examined. We find that Al and Fe both effect the transition pressure, but that the high-pressure phase is still P21/c HPCEN2 in all cases. The single-crystal elasticity diopside was measured to transition zone pressures using Brillouin spectroscopy. A very dense high-quality velocity data set was obtained, from which the single-crystal elastic moduli as a function of pressure were obtained. Results for the aggregate bulk elastic properties are in very good agreement with polycrystalline acoustic measurements of Li and Neuville. This is a case where the results of single-crystal Brillouin and polycrystalline acoustic measurements give highly consistent results. Li, B.S., and Neuville, D.R. (2010) Elasticity of diopside to 8 GPa and 1073 K and implications for the upper mantle. Physics of the Earth and Planetary Interiors, 183(3-4), 398-403. Zhang, JS, P Dera, and JD Bass (2012) A new high-pressure phase transition in natural Fe

  5. A novel stiffness control method for series elastic actuator

    NASA Astrophysics Data System (ADS)

    Lin, Guangmo; Zhao, Xingang; Han, Jianda

    2017-01-01

    Compliance plays an important role in human-robot cooperation. However, fixed compliance, or fixed stiffness, is difficult to meet the growing needs of human machine collaboration. As a result, the robot actuator is demanded to be able to adjust its stiffness. This paper presents a stiffness control scheme for a single DOF series elastic actuator (SEA) with a linear spring mounted in series in the mechanism. In this proposed method, the output angle of the spring is measured and used to calculate the input angle of the spring, thus the equivalent stiffness of the robot actuator revealed to the human operator can be rendered in accordance to the desired stiffness. Since the techniques used in this method only involve the position information of the system, there is no need to install an expensive force/torque sensor on the actuator. Further, the force/torque produced by the actuator can be estimated by simply multiplying the deformation angle of the spring and its constant stiffness coefficient. The analysis of the stiffness controller is provided. Then a simulation that emulates a human operates the SEA while the stiffness controller is running is carried out and the results also validate the proposed method.

  6. Novel Super-Elastic Materials for Advanced Bearing Applications

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher

    2014-01-01

    Tribological surfaces of mechanical components encounter harsh conditions in terrestrial, marine and aerospace environments. Brinell denting, abrasive wear and fatigue often lead to life-limiting bearing and gear failures. Novel superelastic materials based upon Ni-Ti alloys are an emerging solution. Ni-Ti alloys are intermetallic materials that possess characteristics of both metals and ceramics. Ni-Ti alloys have intrinsically good aqueous corrosion resistance (they cannot rust), high hardness, relatively low elastic modulus, are chemically inert and readily lubricated. Ni-Ti alloys also belong to the family of superelastics and, despite high hardness, are able to withstand large strains without suffering permanent plastic deformation. In this paper, the use of hard, resilient Ni-Ti alloys for corrosion-proof, shockproof bearing and gear applications are presented. Through a series of bearing and gear development projects, it is demonstrated that Ni-Tis unique blend of materials properties lead to significantly improved load capacity, reduced weight and intrinsic corrosion resistance not found in any other bearing materials. Ni-Ti thus represents a new materials solution to demanding tribological applications.

  7. Refrigerated Warehouse Demand Response Strategy Guide

    SciTech Connect

    Scott, Doug; Castillo, Rafael; Larson, Kyle; Dobbs, Brian; Olsen, Daniel

    2015-11-01

    This guide summarizes demand response measures that can be implemented in refrigerated warehouses. In an appendix, it also addresses related energy efficiency opportunities. Reducing overall grid demand during peak periods and energy consumption has benefits for facility operators, grid operators, utility companies, and society. State wide demand response potential for the refrigerated warehouse sector in California is estimated to be over 22.1 Megawatts. Two categories of demand response strategies are described in this guide: load shifting and load shedding. Load shifting can be accomplished via pre-cooling, capacity limiting, and battery charger load management. Load shedding can be achieved by lighting reduction, demand defrost and defrost termination, infiltration reduction, and shutting down miscellaneous equipment. Estimation of the costs and benefits of demand response participation yields simple payback periods of 2-4 years. To improve demand response performance, it’s suggested to install air curtains and another form of infiltration barrier, such as a rollup door, for the passageways. Further modifications to increase efficiency of the refrigeration unit are also analyzed. A larger condenser can maintain the minimum saturated condensing temperature (SCT) for more hours of the day. Lowering the SCT reduces the compressor lift, which results in an overall increase in refrigeration system capacity and energy efficiency. Another way of saving energy in refrigerated warehouses is eliminating the use of under-floor resistance heaters. A more energy efficient alternative to resistance heaters is to utilize the heat that is being rejected from the condenser through a heat exchanger. These energy efficiency measures improve efficiency either by reducing the required electric energy input for the refrigeration system, by helping to curtail the refrigeration load on the system, or by reducing both the load and required energy input.

  8. Elastic Correlations in Nucleosomal DNA Structure

    NASA Astrophysics Data System (ADS)

    Mohammad-Rafiee, Farshid; Golestanian, Ramin

    2005-06-01

    The structure of DNA in the nucleosome core particle is studied using an elastic model that incorporates anisotropy in the bending energetics and twist-bend coupling. Using the experimentally determined structure of nucleosomal DNA [T. J. Richmond and C. A. Davey, Nature (London), NATUAS, 0028-0836 423, 145 (2003), 10.1038/nature01595], it is shown that elastic correlations exist between twist, roll, tilt, and stretching of DNA, as well as the distance between phosphate groups. The twist-bend coupling term is shown to be able to capture these correlations to a large extent, and a fit to the experimental data yields a new estimate of G=25 nm for the value of the twist-bend coupling constant.

  9. Hypo-Elastic Model for Lung Parenchyma

    SciTech Connect

    Freed, Alan D.; Einstein, Daniel R.

    2012-03-01

    A simple elastic isotropic constitutive model for the spongy tissue in lung is derived from the theory of hypoelasticity. The model is shown to exhibit a pressure dependent behavior that has been interpreted by some as indicating extensional anisotropy. In contrast, we show that this behavior arises natural from an analysis of isotropic hypoelastic invariants, and is a likely result of non-linearity, not anisotropy. The response of the model is determined analytically for several boundary value problems used for material characterization. These responses give insight into both the material behavior as well as admissible bounds on parameters. The model is characterized against published experimental data for dog lung. Future work includes non-elastic model behavior.

  10. A mathematical model of elastic fin micromotors

    NASA Astrophysics Data System (ADS)

    Lu, Pin; Lee, Kwok Hong; Piang Lim, Siak; Dong, Shuxiang; Zhong Lin, Wu

    2000-08-01

    In the present work, a simplified mathematical model of ultrasonic elastic fin micromotors has been developed. According to the operating principle of this type of motor, the motions of a rotor in each cycle of the stator vibration are divided into several stages based on whether the fin tip and the stator are in contact with slip, contact without slip or separation. The equations of motion of the rotor in each stage are derived. The valid range of the model has been discussed through numerical examples. This work provides an initial effort to construct a model for the elastic fin motor by considering the dynamical deformation of the rotor as well as the intermittent contacts.

  11. Three-dimensional elastic lidar winds

    SciTech Connect

    Buttler, W.T.

    1996-07-01

    Maximum cross-correlation techniques have been used with satellite data to estimate winds and sea surface velocities for several years. Los Alamos National Laboratory (LANL) is currently using a variation of the basic maximum cross-correlation technique, coupled with a deterministic application of a vector median filter, to measure transverse winds as a function of range and altitude from incoherent elastic backscatter lidar data taken throughout large volumes within the atmospheric boundary layer. Hourly representations of three- dimensional wind fields, derived from elastic lidar data taken during an air-quality study performed in a region of complex terrain near Sunland Park, New Mexico, are presented and compared with results from an Environmental Protection Agency (EPA) approved laser doppler velocimeter. The wind fields showed persistent large scale eddies as well as general terrain following winds in the Rio Grande valley.

  12. On the magnetorotational instability and elastic buckling

    PubMed Central

    Vasil, Geoffrey M.

    2015-01-01

    This paper demonstrates an equivalence between rotating magnetized shear flows and a stressed elastic beam. This results from finding the same form of dynamical equations after an asymptotic reduction of the axis-symmetric magnetorotational instability (MRI) under the assumption of almost-critical driving. The analysis considers the MRI dynamics in a non-dissipative near-equilibrium regime. Both the magnetic and elastic systems reduce to a simple one-dimensional wave equation with a non-local nonlinear feedback. Under transformation, the equation comprises a large number of mean-field interacting Duffing oscillators. This system was the first proven example of a strange attractor in a partial differential equation. Finding the same reduced equation in two natural applications suggests the model might result from other applications and could fall into a universal class based on symmetry. PMID:27547088

  13. Elasticity and Strength of Biomacromolecular Crystals: Lysozyme

    NASA Technical Reports Server (NTRS)

    Holmes, A. M.; Witherow, W. K.; Chen, L. Q.; Chernov, A. A.

    2003-01-01

    The static Young modulus, E = 0.1 to 0.5 GPa, the crystal critical strength (sigma(sub c)) and its ratio to E,sigma(sub c)/E is approximately 10(exp 3), were measured for the first time for non cross-linked lysozyme crystals in solution. By using a triple point bending apparatus, we also demonstrated that the crystals were purely elastic. Softness of protein crystals built of hard macromolecules (26 GPa for lysozyme) is explained by the large size of the macromolecules as compared to the range of intermolecular forces and by the weakness of intermolecular bonds as compared to the peptide bond strength. The relatively large reported dynamic elastic moduli (approximately 8 GPa) from resonance light scattering should come from averaging over the moduli of intracrystalline water and intra- and intermolecular bonding.

  14. From Elastic Continua To Space-time

    NASA Astrophysics Data System (ADS)

    Tartaglia, Angelo; Radicella, Ninfa

    2010-06-01

    Since the early days of the theory of electromagnetism and of gravity the idea of space, then space-time, as a sort of physical continuum hovered the scientific community. Actually general relativity shows the strong similarity that exists between the geometrical properties of space-time and the ones of a strained elastic continuum. The bridge between geometry and the elastic potential, as well in three as in three plus one dimensions, is the strain tensor, read as the non-trivial part of the metric tensor. On the basis of this remark and exploiting appropriate multidimensional embeddings, it is possible to build a full theory of space-time, allowing to account for the accelerated expansion of the universe. How this can be obtained is the content of the paper. The theory fits the cosmic accelerated expansion data from type Ia supernovae better than the □CDM model.

  15. Strong tissue glue with tunable elasticity.

    PubMed

    Kelmansky, Regina; McAlvin, Brian J; Nyska, Abraham; Dohlman, Jenny C; Chiang, Homer H; Hashimoto, Michinao; Kohane, Daniel S; Mizrahi, Boaz

    2017-02-09

    Many bio-adhesive materials adhere weakly to tissue due to their high water content and weak structural integrity. Others provide desirable adhesive strength but suffer from rigid structure and lack of elasticity after administration. We have developed two water-free, liquid four-armed PEG pre-polymers modified with NHS or with NH2 end groups which upon mixing changed from liquids to an elastic solid. The sealant and adhesive properties increased with the amount of the %v/v PEG4-NHS pre-polymer, and achieved adhesive properties comparable to those of cyanoacrylate glues. All mixtures showed minimal cytotoxicity in vitro. Mixtures of 90%v/v PEG4-NHS were retained in the subcutaneous space in vivo for up to 14days with minimal inflammation. This material's combination of desirable mechanical properties and biocompatibility has potential in numerous biomedical applications.

  16. Determining Elasticity from Single Polymer Dynamics

    PubMed Central

    Latinwo, Folarin

    2014-01-01

    The ability to determine polymer elasticity and force-extension relations from polymer dynamics in flow has been challenging, mainly due to difficulties in relating equilibrium properties such as free energy to far-from-equilibrium processes. In this work, we determine polymer elasticity from the dynamic properties of polymer chains in fluid flow using recent advances in statistical mechanics. In this way, we obtain the force-extension relation for DNA from single molecule measurements of polymer dynamics in flow without the need for optical tweezers or bead tethers. We further employ simulations to demonstrate the practicality and applicability of this approach to the dynamics of complex fluids. We investigate the effects of flow type on this analysis method, and we develop scaling laws to relate the work relation to bulk polymer viscometric functions. Taken together, our results show that nonequilibrium work relations can play a key role in the analysis of soft material dynamics. PMID:24651921

  17. Non-affine elasticity in jammed systems

    NASA Astrophysics Data System (ADS)

    Maloney, Craig

    2006-03-01

    Symmetry dictates that perfect crystals should deform homogeneously, or affinely, under external load, and computing the elastic moduli from the underlying interaction potential is then straightforward. For disordered materials no such simple procedure exists, and recent numerical works have demonstrated that non-affine corrections can dramatically reduce the naive expectation for the shear modulus in a broad class of disordered systems and may control rigidity loss in the zero pressure limit in purely repulsive systems, i.e. the unjamming transition (c.f. [O'Hern et. al. PRE 68, 011306 (2003)]). We present numerical results and an analytical framework for the study of these non-affine corrections to the elastic response of disordered packings.

  18. A Double-Strand Elastic Rod Theory

    NASA Astrophysics Data System (ADS)

    Moakher, Maher; Maddocks, John H.

    2005-07-01

    Motivated by applications in the modeling of deformations of the DNA double helix, we construct a continuum mechanics model of two elastically interacting elastic strands. The two strands are described in terms of averaged, or macroscopic, variables plus an additional small, internal or microscopic, perturbation. We call this composite structure a birod. The balance laws for the macroscopic configuration variables of the birod can be cast in the form of a classic Cosserat rod model with coupling to the internal balance laws through the constitutive relations. The internal balance laws for the microstructure variables also take a mathematical form analogous to that for a Cosserat rod, but with coupling to the macroscopic system through terms corresponding to distributed force and couple loads.

  19. Measurement of elastic properties of blood vessels.

    PubMed

    Ilic, D; Moix, T; Lambercy, O; Sache, L; Bleuler, H; Ohta, M; Augsburger, L

    2005-01-01

    This paper is related to the measurements of the modulus of elasticity of an artery by studying the deformations due to the inflation of an angioplasty balloon catheter used for Interventional Radiology (IR) procedures. Various types of balloons are studied in order to characterize and compare their behaviors at the time of inflation. A test bench, consisting of an angioplasty balloon, a Polyvinyl alcohol model and an actuator used to inflate a balloon, is developed for the realization of the experiments. The pressure-volume curve during the inflation of a balloon is observed. Elasticity modulus are derived with an analytical model of the measurement system. The results are then analyzed and compared to existing data from literature.

  20. Rubber elasticity: From topology to filled elastomers

    SciTech Connect

    Heinrich, G.; Vilgis, T.A.

    1993-12-31

    Various new aspects in the elasticity of rubbers and statistics of unfilled and filled elastomers, together with various consequences for practical application are discussed. It is shown that the role of network topology is crucial in the statistics of rubbers. This is seen mostly on the influence of heterogeneities of crosslink density which determine the elastic modulus, ultimate properties as well as the dynamical behavior. The filler effects, entanglements in filled rubbers, and the filler/bound rubber/mobile rubber problem are discussed from a novel point of view. A localization model is adopted, where it can be shown that on a rough (filler) surface more polymer can be adsorbed compared to a flat surface with similar energetic properties. The role of carbon black networking and fractal properties of the filler are discussed in relation to the dynamic-mechanical properties of the elastomer.

  1. Strength reduction in electrical and elastic networks

    NASA Astrophysics Data System (ADS)

    Espinoza Ortiz, J. S.; Rajapakse, Chamith S.; Gunaratne, Gemunu H.

    2002-10-01

    Particular aspects of problems ranging from dielectric breakdown to metal-insulator transition can be studied using electrical or elastic networks. We present an expression for the mean breakdown strength of such networks. First, we introduce a method to evaluate the redistribution of current due to the removal of a finite number of elements from a hypercubic network of conductances. It is used to determine the reduction of breakdown strength due to a fracture of size κ. Numerical analysis is used to show that the analogous reduction due to random removal of elements from electrical and elastic networks follow a similar form. One possible application, namely the use of bone density as a diagnostic tool for osteoporosis, is discussed.

  2. Experiments on Elastic Cloaking in Thin Plates

    NASA Astrophysics Data System (ADS)

    Stenger, Nicolas; Wilhelm, Manfred; Wegener, Martin

    2012-01-01

    Following a theoretical proposal [M. Farhat , Phys. Rev. Lett. 103, 024301 (2009)PRLTAO0031-900710.1103/PhysRevLett.103.024301], we design, fabricate, and characterize a cloaking structure for elastic waves in 1 mm thin structured polymer plates. The cloak consists of 20 concentric rings of 16 different metamaterials, each being a tailored composite of polyvinyl chloride and polydimethylsiloxane. By using stroboscopic imaging with a camera from the direction normal to the plate, we record movies of the elastic waves for monochromatic plane-wave excitation. We observe good cloaking behavior for carrier frequencies in the range from 200 to 400 Hz (one octave), in good agreement with a complete continuum-mechanics numerical treatment. This system is thus ideally suited for demonstration experiments conveying the ideas of transformation optics.

  3. Localization in an Idealized Heterogeneous Elastic Sheet

    NASA Astrophysics Data System (ADS)

    Gurmessa, Bekele; Croll, Andrew B.

    2015-03-01

    Localized deformation is ubiquitous in many natural and engineering materials. Often times such deformations are associated to non-homogeneous strain fields in the materials. In this work we demonstrate the response of idealized non-homogenous elastic sheets to uniaxial compression. The idealized/patterned surface layers are created by selective ultraviolet/ozone (UVO) treatment of the top surface of polydimethylsiloxane (PDMS) using TEM grid mask. By controlling the exposure time of the UVO, samples ranging from continuous thin films to sets of isolated small plates were created. We show how local strains vary with location in a patterned sample, leading to a complex localization process Even at low strains. We also see that continuous regions form isotropic undulations upon compression which persist to high strains, well beyond where localization is observed in the patterned regions. Despite the complexity, the localized deformation profile can be adequately described with a simple elastic model when appropriate local boundary conditions are considered.

  4. USGS Map-on-Demand Printing

    USGS Publications Warehouse

    ,

    1999-01-01

    Currently, the U.S. Geological Survey (USGS) uses conventional lithographic printing techniques to produce paper copies of most of its mapping products. This practice is not economical for those products that are in low demand. With the advent of newer technologies, high-speed, large-format printers have been coupled with innovative computer software to turn digital map data into a printed map. It is now possible to store and retrieve data from vast geospatial data bases and print a map on an as-needed basis; that is, print on demand, thereby eliminating the need to warehouse an inventory of paper maps for which there is low demand. Using print-on-demand technology, the USGS is implementing map-on-demand (MOD) printing for certain infrequently requested maps. By providing MOD, the USGS can offer an alternative to traditional, large-volume printing and can improve its responsiveness to customers by giving them greater access to USGS scientific data in a format that otherwise might not be available.

  5. Analysing the lack of Demand Organisation

    NASA Astrophysics Data System (ADS)

    Boxer, Philip; Cohen, Bernard

    1998-07-01

    We seek to develop means of intervention in Enterprises that will enable them to react in an effective, sustainable and timely fashion to changes in the ways that markets and demand are organized; that is, to act strategically. We take an enterprise to be some entity that seeks to provide its clients with services that they value while maintaining its ability to do so in the face of changes in the demands of its clients and in the resources at its disposal. The services that clients value form around what the organization of their demands lack. The concept of strategy therefore rests on critically evaluating the ontology and semantics of the Enterprise in relation to these holes in demand organization. We access ontology and semantics by constructing and manipulating hypothetical, first-order, mathematical models of the Enterprise's services and of its value-adding processes. Because an enterprise is an anticipatory system, its semantic domain must include representations of the enterprise's model of itself and of the market and demand organizations within which it competes. First-order (set) theory provides adequate expressive power here, but alternative, higher order, mathematical frameworks, such as Dubois' hyperincursion, provide inadequate power, particularly in relation to the analysis of the properties of emergence. Knowing exactly why and where this mathematical lack manifests in the analysis process enables effective collaboration between systems analysts and psychoanalysts, and suggest directions for mathematical research.

  6. Regional recreation demand and benefits model

    SciTech Connect

    Sutherland, R.J.

    1983-03-01

    This report describes a regional recreation demand and benefits model that is used to estimate recreation demand and value (consumers' surplus) of four activities at each of 195 sites in Washington, Oregon, Idaho, and western Montana. The recreation activities considered are camping, fishing, swimming, and boating. The model is a generalization of the single-site travel-cost method of estimating a recreation demand curve to virtually an unlimited number of sites. The major components of the analysis include the theory of recreation benefits, a travel-cost recreation demand curve, and a gravity model of regional recreation travel flows. Existing recreation benefits are estimated for each site in the region and for each activity. Recreation benefits of improved water quality in degraded rivers and streams in the Pacific Northwest are estimated on a county basis for Washington, Oregon, and Idaho. Although water quality is emphasized, the model has the capability of estimating demand and value for new or improved recreation sites at lakes, streams, or reservoirs.

  7. A modified exponential behavioral economic demand model to better describe consumption data.

    PubMed

    Koffarnus, Mikhail N; Franck, Christopher T; Stein, Jeffrey S; Bickel, Warren K

    2015-12-01

    Behavioral economic demand analyses that quantify the relationship between the consumption of a commodity and its price have proven useful in studying the reinforcing efficacy of many commodities, including drugs of abuse. An exponential equation proposed by Hursh and Silberberg (2008) has proven useful in quantifying the dissociable components of demand intensity and demand elasticity, but is limited as an analysis technique by the inability to correctly analyze consumption values of zero. We examined an exponentiated version of this equation that retains all the beneficial features of the original Hursh and Silberberg equation, but can accommodate consumption values of zero and improves its fit to the data. In Experiment 1, we compared the modified equation with the unmodified equation under different treatments of zero values in cigarette consumption data collected online from 272 participants. We found that the unmodified equation produces different results depending on how zeros are treated, while the exponentiated version incorporates zeros into the analysis, accounts for more variance, and is better able to estimate actual unconstrained consumption as reported by participants. In Experiment 2, we simulated 1,000 datasets with demand parameters known a priori and compared the equation fits. Results indicated that the exponentiated equation was better able to replicate the true values from which the test data were simulated. We conclude that an exponentiated version of the Hursh and Silberberg equation provides better fits to the data, is able to fit all consumption values including zero, and more accurately produces true parameter values.

  8. Cognitive task demands, self-control demands and the mental well-being of office workers.

    PubMed

    Bridger, Robert S; Brasher, Kate

    2011-09-01

    The cognitive task demands of office workers and the self-control demands of their work roles were measured in a sample of 196 employees in two different office layouts using a self-report questionnaire, which was circulated electronically. Multiple linear regression analysis revealed that both factors were associated with mental well-being, but not with physical well-being, while controlling for exposure to psychosocial stressors. The interaction between cognitive task demands and self-control demands had the strongest association with mental well-being, suggesting that the deleterious effect of one was greater when the other was present. An exploratory analysis revealed that the association was stronger for employees working in a large open-plan office than for those working in smaller offices with more privacy. Frustration of work goals was the cognitive task demand having the strongest negative impact on mental well-being. Methodological limitations and scale psychometrics (particularly the use of the NASA Task Load Index) are discussed. STATEMENT OF RELEVANCE: Modern office work has high mental demands and low physical demands and there is a need to design offices to prevent adverse psychological reactions. It is shown that cognitive task demands interact with self-control demands to degrade mental well-being. The association was stronger in an open-plan office.

  9. The Hugoniot Elastic Limit of ALON

    NASA Astrophysics Data System (ADS)

    Cazamias, James U.; Fiske, Peter S.; Bless, Stephan J.

    2002-07-01

    We performed plate impact experiments on the transparent polycrystalline ceramic aluminum oxynitride (AlON, transparent alumina). From VISAR measurements, the Hugoniot Elastic Limit, sigmaHEL, is 11.0-11.4 GPa with a corresponding yield strength of 7.2-7.5 GPa. A transverse gauge gives a yield strength of 8.7 GPa for a longitudinal stress of 13.9 GPa, which implies that the failed AlON possesses at least its sigmaHEL strength.

  10. Decay of elastic waves in alumina

    NASA Astrophysics Data System (ADS)

    Marom, H.; Sherman, D.; Rosenberg, Z.

    2000-11-01

    The dynamic response of alumina under shock compression was studied using planar impact experiments with different tile thicknesses. Stress-time measurements were made with manganin gauges backed by different backing materials in order to optimize gauge response. The results show an apparent decay in the Hugoniot elastic limit with propagation distance. However, further analysis reveals that this phenomenon is probably a measurement artifact, resulting from the relatively slow response times of manganin gauges.

  11. Elastic Instability in Growing Yeast Colonies

    PubMed Central

    Nguyen, Baochi; Upadhyaya, Arpita; van Oudenaarden, Alexander; Brenner, Michael P.

    2004-01-01

    The differential adhesion between cells is believed to be the major driving force behind the formation of tissues. The idea is that an aggregate of cells minimizes the overall adhesive energy between cell surfaces. We demonstrate in a model experimental system that there exist conditions where a slowly growing tissue does not minimize this adhesive energy. A mathematical model demonstrates that the instability of a spherical shape is caused by the competition between elastic and surface energies. PMID:15111392

  12. On contact problems of elasticity theory

    NASA Technical Reports Server (NTRS)

    Kalandiya, A. I.

    1986-01-01

    Certain contact problems are reviewed in the two-dimensional theory of elasticity when round bodies touch without friction along most of the boundary and, therefore, Herz' hypothesis on the smallness of the contact area cannot be used. Fundamental equations were derived coinciding externally with the equation in the theory of a finite-span wing with unkown parameter. These equations are solved using Multhopp's well-known technique, and numerical calculations are performed in specific examples.

  13. Elastic electron scattering from formic acid

    SciTech Connect

    Trevisan, Cynthia S.; Orel, Ann E.; Rescigno, Thomas N.

    2006-07-31

    Following our earlier study on the dynamics of low energy electron attachment to formic acid, we report the results of elastic low-energy electron collisions with formic acid. Momentum transfer and angular differential cross sections were obtained by performing fixed-nuclei calculations employing the complex Kohn variational method. We make a brief description of the technique used to account for the polar nature of this polyatomic target and compare our results with available experimental data.

  14. Thermal elastic deformations of the planet Mercury.

    NASA Technical Reports Server (NTRS)

    Liu, H.-S.

    1972-01-01

    The variation in solar heating due to the resonance rotation of Mercury produces periodic elastic deformations on the surface of the planet. The thermal stress and strain fields under Mercury's surface are calculated after certain simplifications. It is found that deformations penetrate to a greater depth than the variation of solar heating, and that the thermal strain on the surface of the planet pulsates with an amplitude of .004 and a period of 176 days.

  15. Thermal elastic deformations of the planet Mercury

    NASA Technical Reports Server (NTRS)

    Liu, H.

    1971-01-01

    The variation in solar heating due to the resonance rotation of Mercury produces periodic elastic deformations on the surface of the planet. The thermal stress and strain fields under Mercury's surface are calculated after certain simplifications. It is shown that deformations penetrate to a greater depth than the variation of solar heating, and that the thermal strain on the surface of the planet pulsates with an amplitude of 0.004 and a period of 176 days.

  16. 31 CFR 344.7 - What are Demand Deposit securities?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false What are Demand Deposit securities... LOCAL GOVERNMENT SERIES Demand Deposit Securities § 344.7 What are Demand Deposit securities? Demand... in the Federal Register. (b) What happens to Demand Deposit securities during a Debt...

  17. Elastic properties of NaXH4 (X = B, Al)

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Dong; Jiang, Zhen-Yi; Hou, Yu-Qing; Li, Li-Sha

    2009-07-01

    Elastic properties of NaXH4 (X = B, Al) have been studied by first-principles calculations using a projected augmented plane-wave approach. The calculated elastic constants compare favorably with experimental values. Our calculations show that the theoretically calculated elastic constants and bulk moduli have small values compared with those of typical metals and intermetallic compounds, which indicates that NaXH4 (X = B, Al) are highly compressible. Comparison of bulk moduli B of different complex hydrides shows a correlation between B and the decomposition temperatures. Also, we calculated the elastic anisotropies and the Debye temperatures from the elastic constants.

  18. Elasticity of the Rod-Shaped Gram-Negative Eubacteria

    NASA Astrophysics Data System (ADS)

    Boulbitch, A.; Quinn, B.; Pink, D.

    2000-12-01

    We report a theoretical calculation of the elasticity of the peptidoglycan network, the only stress-bearing part of rod-shaped Gram-negative eubacteria. The peptidoglycan network consists of elastic peptides and inextensible glycan strands, and it has been proposed that the latter form zigzag filaments along the circumference of the cylindrical bacterial shell. The zigzag geometry of the glycan strands gives rise to nonlinear elastic behavior. The four elastic moduli of the peptidoglycan network depend on its stressed state. For a bacterium under physiological conditions the elasticity is proportional to the bacterial turgor pressure. Our results are in good agreement with recent measurements.

  19. Hysteresis and the Dynamic Elasticity of Consolidated Granular Materials

    SciTech Connect

    Guyer, R.A.; TenCate, J.; Johnson, P.

    1999-04-01

    Quasistatic elasticity measurements on rocks show them to be strikingly nonlinear and to have elastic hysteresis with end point memory. When the model for this quasistatic elasticity is extended to the description of nonlinear dynamic elasticity the elastic elements responsible for the hysteresis dominate the behavior. Consequently, in a resonant bar, driven to nonlinearity, the frequency shift and the attenuation are predicted to be nonanalytic functions of the strain field. A resonant bar experiment yielding results in substantial qualitative and quantitative accord with these predictions is reported. {copyright} {ital 1999} {ital The American Physical Society }

  20. Tissue elasticity measurement method using forward and inversion algorithms

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Ha; Won, Chang-Hee; Park, Hee-Jun; Ku, Jeonghun; Heo, Yun Seok; Kim, Yoon-Nyun

    2013-03-01

    Elasticity is an important indicator of tissue health, with increased stiffness pointing to an increased risk of cancer. We investigated a tissue elasticity measurement method using forward and inversion algorithms for the application of early breast tumor identification. An optical based elasticity measurement system is developed to capture images of the embedded lesions using total internal reflection principle. From elasticity images, we developed a novel method to estimate the elasticity of the embedded lesion using 3-D finite-element-model-based forward algorithm, and neural-network-based inversion algorithm. The experimental results showed that the proposed characterization method can be diffierentiate the benign and malignant breast lesions.

  1. Elastic properties of overpressured and unconsolidated sediments

    USGS Publications Warehouse

    Lee, Myung W.

    2003-01-01

    Differential pressure affects elastic velocities and Poisson?s ratio of sediments in such a way that velocities increase as differential pressure increases. Overpressured zones in sediments can be detected by observing an increase in Poisson?s ratio with a corresponding drop in elastic velocities. In highly overpressured sands, such as shallow water flow sands, the P-to S-wave velocity ratio (Vp/Vs) is very high, on the order of 10 or higher, due to the unconsolidated and uncemented nature of sediments. In order to predict elastic characteristics of highly overpressured sands, Biot-Gassmann theory by Lee (BGTL) is used with a variable exponent n that depends on differential pressure and the degree of consolidation/compaction. The exponent n decreases as differential pressure and the degree of consolidation increases, and, as n decreases, velocity increases and Vp/Vs decreases. The predicted velocity ratio by BGTL agrees well with the measured velocity ratio at low differential pressure for unconsolidated sediments.

  2. A cohesive granular material with tunable elasticity

    PubMed Central

    Hemmerle, Arnaud; Schröter, Matthias; Goehring, Lucas

    2016-01-01

    By mixing glass beads with a curable polymer we create a well-defined cohesive granular medium, held together by solidified, and hence elastic, capillary bridges. This material has a geometry similar to a wet packing of beads, but with an additional control over the elasticity of the bonds holding the particles together. We show that its mechanical response can be varied over several orders of magnitude by adjusting the size and stiffness of the bridges, and the size of the particles. We also investigate its mechanism of failure under unconfined uniaxial compression in combination with in situ x-ray microtomography. We show that a broad linear-elastic regime ends at a limiting strain of about 8%, whatever the stiffness of the agglomerate, which corresponds to the beginning of shear failure. The possibility to finely tune the stiffness, size and shape of this simple material makes it an ideal model system for investigations on, for example, fracturing of porous rocks, seismology, or root growth in cohesive porous media. PMID:27774988

  3. Packing of elastic wires in flexible shells

    NASA Astrophysics Data System (ADS)

    Vetter, R.; Wittel, F. K.; Herrmann, H. J.

    2015-11-01

    The packing problem of long thin filaments that are injected into confined spaces is of fundamental interest for physicists and biologists alike. How linear threads pack and coil is well known only for the ideal case of rigid containers, though. Here, we force long elastic rods into flexible spatial confinement borne by an elastic shell to examine under which conditions recently acquired knowledge on wire packing in rigid spheres breaks down. We find that unlike in rigid cavities, friction plays a key role by giving rise to the emergence of two distinct packing patterns. At low friction, the wire densely coils into an ordered toroidal bundle with semi-ellipsoidal cross-section, while at high friction, it packs into a highly disordered, hierarchic structure. These two morphologies are shown to be separated by a continuous phase transition. Our findings demonstrate the dramatic impact of friction and confinement elasticity on filamentous packing and might drive future research on such systems in physics, biology and even medical technology toward including these mutually interacting effects.

  4. A cohesive granular material with tunable elasticity

    NASA Astrophysics Data System (ADS)

    Hemmerle, Arnaud; Schröter, Matthias; Goehring, Lucas

    2016-10-01

    By mixing glass beads with a curable polymer we create a well-defined cohesive granular medium, held together by solidified, and hence elastic, capillary bridges. This material has a geometry similar to a wet packing of beads, but with an additional control over the elasticity of the bonds holding the particles together. We show that its mechanical response can be varied over several orders of magnitude by adjusting the size and stiffness of the bridges, and the size of the particles. We also investigate its mechanism of failure under unconfined uniaxial compression in combination with in situ x-ray microtomography. We show that a broad linear-elastic regime ends at a limiting strain of about 8%, whatever the stiffness of the agglomerate, which corresponds to the beginning of shear failure. The possibility to finely tune the stiffness, size and shape of this simple material makes it an ideal model system for investigations on, for example, fracturing of porous rocks, seismology, or root growth in cohesive porous media.

  5. Stress Formulation in Three-Dimensional Elasticity

    NASA Technical Reports Server (NTRS)

    Patnaik, Surya N.; Hopkins, Dale A.

    2001-01-01

    The theory of elasticity evolved over centuries through the contributions of eminent scientists like Cauchy, Navier, Hooke Saint Venant, and others. It was deemed complete when Saint Venant provided the strain formulation in 1860. However, unlike Cauchy, who addressed equilibrium in the field and on the boundary, the strain formulation was confined only to the field. Saint Venant overlooked the compatibility on the boundary. Because of this deficiency, a direct stress formulation could not be developed. Stress with traditional methods must be recovered by backcalculation: differentiating either the displacement or the stress function. We have addressed the compatibility on the boundary. Augmentation of these conditions has completed the stress formulation in elasticity, opening up a way for a direct determination of stress without the intermediate step of calculating the displacement or the stress function. This Completed Beltrami-Michell Formulation (CBMF) can be specialized to derive the traditional methods, but the reverse is not possible. Elasticity solutions must be verified for the compliance of the new equation because the boundary compatibility conditions expressed in terms of displacement are not trivially satisfied. This paper presents the variational derivation of the stress formulation, illustrates the method, examines attributes and benefits, and outlines the future course of research.

  6. Thermoelectric Polymers and their Elastic Aerogels.

    PubMed

    Khan, Zia Ullah; Edberg, Jesper; Hamedi, Mahiar Max; Gabrielsson, Roger; Granberg, Hjalmar; Wågberg, Lars; Engquist, Isak; Berggren, Magnus; Crispin, Xavier

    2016-06-01

    Electronically conducting polymers constitute an emerging class of materials for novel electronics, such as printed electronics and flexible electronics. Their properties have been further diversified to introduce elasticity, which has opened new possibility for "stretchable" electronics. Recent discoveries demonstrate that conducting polymers have thermoelectric properties with a low thermal conductivity, as well as tunable Seebeck coefficients - which is achieved by modulating their electrical conductivity via simple redox reactions. Using these thermoelectric properties, all-organic flexible thermoelectric devices, such as temperature sensors, heat flux sensors, and thermoelectric generators, are being developed. In this article we discuss the combination of the two emerging fields: stretchable electronics and polymer thermoelectrics. The combination of elastic and thermoelectric properties seems to be unique for conducting polymers, and difficult to achieve with inorganic thermoelectric materials. We introduce the basic concepts, and state of the art knowledge, about the thermoelectric properties of conducting polymers, and illustrate the use of elastic thermoelectric conducting polymer aerogels that could be employed as temperature and pressure sensors in an electronic-skin.

  7. An automated nudged elastic band method

    NASA Astrophysics Data System (ADS)

    Kolsbjerg, Esben L.; Groves, Michael N.; Hammer, Bjørk

    2016-09-01

    A robust, efficient, dynamic, and automated nudged elastic band (AutoNEB) algorithm to effectively locate transition states is presented. The strength of the algorithm is its ability to use fewer resources than the nudged elastic band (NEB) method by focusing first on converging a rough path before improving upon the resolution around the transition state. To demonstrate its efficiency, it has been benchmarked using a simple diffusion problem and a dehydrogenation reaction. In both cases, the total number of force evaluations used by the AutoNEB method is significantly less than the NEB method. Furthermore, it is shown that for a fast and robust relaxation to the transition state, a climbing image elastic band method where the full spring force, rather than only the component parallel to the local tangent to the path, is preferred especially for pathways through energy landscapes with multiple local minima. The resulting corner cutting does not affect the accuracy of the transition state as long as this is located with the climbing image method. Finally, a number of pitfalls often encountered while locating the true transition state of a reaction are discussed in terms of systematically exploring the multidimensional energy landscape of a given process.

  8. Hospital demand for licensed practical nurses.

    PubMed

    Spetz, Joanne; Dyer, Wendy T; Chapman, Susan; Seago, Jean Ann

    2006-10-01

    Despite evidence that hospital use of licensed practical nurses (LPNs) declined in the 1990s, the current registered nurse (RN) shortage has prompted interest in LPNs as substitutes for RNs. Hospitals, being the dominant employer of RNs, have an economic incentive to use less expensive LPNs as substitutes. Beside wages, there are several forces underlying hospital demand for LPNs. In this article, the authors model and estimate hospital demand for LPNs as a function of nurse wages and hospital, market, and patient characteristics using a longitudinal data set of short-term general hospitals in the United States. The authors find evidence that higher RN wages increase hospital demand for LPNs, both in levels and relative to RNs, suggesting that hospitals at least partially substitute RNs with LPNs.

  9. Wireless Demand Response Controls for HVAC Systems

    SciTech Connect

    Federspiel, Clifford

    2009-06-30

    The objectives of this scoping study were to develop and test control software and wireless hardware that could enable closed-loop, zone-temperature-based demand response in buildings that have either pneumatic controls or legacy digital controls that cannot be used as part of a demand response automation system. We designed a SOAP client that is compatible with the Demand Response Automation Server (DRAS) being used by the IOUs in California for their CPP program, design the DR control software, investigated the use of cellular routers for connecting to the DRAS, and tested the wireless DR system with an emulator running a calibrated model of a working building. The results show that the wireless DR system can shed approximately 1.5 Watts per design CFM on the design day in a hot, inland climate in California while keeping temperatures within the limits of ASHRAE Standard 55: Thermal Environmental Conditions for Human Occupancy.

  10. International Oil Supplies and Demands. Volume 2

    SciTech Connect

    Not Available

    1992-04-01

    The eleventh Energy Modeling Forum (EMF) working group met four times over the 1989--1990 period to compare alternative perspectives on international oil supplies and demands through 2010 and to discuss how alternative supply and demand trends influence the world`s dependence upon Middle Eastern oil. Proprietors of eleven economic models of the world oil market used their respective models to simulate a dozen scenarios using standardized assumptions. From its inception, the study was not designed to focus on the short-run impacts of disruptions on oil markets. Nor did the working group attempt to provide a forecast or just a single view of the likely future path for oil prices. The model results guided the group`s thinking about many important longer-run market relationships and helped to identify differences of opinion about future oil supplies, demands, and dependence.

  11. International Oil Supplies and Demands. Volume 1

    SciTech Connect

    Not Available

    1991-09-01

    The eleventh Energy Modeling Forum (EMF) working group met four times over the 1989--90 period to compare alternative perspectives on international oil supplies and demands through 2010 and to discuss how alternative supply and demand trends influence the world`s dependence upon Middle Eastern oil. Proprietors of eleven economic models of the world oil market used their respective models to simulate a dozen scenarios using standardized assumptions. From its inception, the study was not designed to focus on the short-run impacts of disruptions on oil markets. Nor did the working group attempt to provide a forecast or just a single view of the likely future path for oil prices. The model results guided the group`s thinking about many important longer-run market relationships and helped to identify differences of opinion about future oil supplies, demands, and dependence.

  12. Utility Sector Impacts of Reduced Electricity Demand

    SciTech Connect

    Coughlin, Katie

    2014-12-01

    This report presents a new approach to estimating the marginal utility sector impacts associated with electricity demand reductions. The method uses publicly available data and provides results in the form of time series of impact factors. The input data are taken from the Energy Information Agency's Annual Energy Outlook (AEO) projections of how the electric system might evolve in the reference case, and in a number of side cases that incorporate different effciency and other policy assumptions. The data published with the AEO are used to define quantitative relationships between demand-side electricity reductions by end use and supply-side changes to capacity by plant type, generation by fuel type and emissions of CO2, Hg, NOx and SO2. The impact factors define the change in each of these quantities per unit reduction in site electricity demand. We find that the relative variation in these impacts by end use is small, but the time variation can be significant.

  13. China's Coal: Demand, Constraints, and Externalities

    SciTech Connect

    Aden, Nathaniel; Fridley, David; Zheng, Nina

    2009-07-01

    This study analyzes China's coal industry by focusing on four related areas. First, data are reviewed to identify the major drivers of historical and future coal demand. Second, resource constraints and transport bottlenecks are analyzed to evaluate demand and growth scenarios. The third area assesses the physical requirements of substituting coal demand growth with other primary energy forms. Finally, the study examines the carbon- and environmental implications of China's past and future coal consumption. There are three sections that address these areas by identifying particular characteristics of China's coal industry, quantifying factors driving demand, and analyzing supply scenarios: (1) reviews the range of Chinese and international estimates of remaining coal reserves and resources as well as key characteristics of China's coal industry including historical production, resource requirements, and prices; (2) quantifies the largest drivers of coal usage to produce a bottom-up reference projection of 2025 coal demand; and (3) analyzes coal supply constraints, substitution options, and environmental externalities. Finally, the last section presents conclusions on the role of coal in China's ongoing energy and economic development. China has been, is, and will continue to be a coal-powered economy. In 2007 Chinese coal production contained more energy than total Middle Eastern oil production. The rapid growth of coal demand after 2001 created supply strains and bottlenecks that raise questions about sustainability. Urbanization, heavy industrial growth, and increasing per-capita income are the primary interrelated drivers of rising coal usage. In 2007, the power sector, iron and steel, and cement production accounted for 66% of coal consumption. Power generation is becoming more efficient, but even extensive roll-out of the highest efficiency units would save only 14% of projected 2025 coal demand for the power sector. A new wedge of future coal consumption is

  14. Why Changes in Price Matter When Thinking About Marijuana Policy: A Review of the Literature on the Elasticity of Demand.

    PubMed

    Pacula, Rosalie Liccardo; Lundberg, Russell

    Recent debates regarding liberalization of marijuana policies often rest on assumptions regarding the extent to which such policy changes would lead to a change in marijuana consumption and by whom. This paper reviews the economics literature assessing the responsiveness of consumption to changes in price and enforcement risk and explicitly considers how this responsiveness varies by different user groups. In doing so, it demonstrates how most of the research has examined responsiveness to prevalence of use, which is a composite of different user groups, rather than level of consumption among regular or heavy users, which represent the largest share of total quantities consumed. Thus, it is not possible to generate reliable estimates of the impact of liberalizing policies on either tax revenues or harms, as these outcomes are most directly influenced by the amounts consumed by regular or heavy users, not prevalence rates.

  15. Why Changes in Price Matter When Thinking About Marijuana Policy: A Review of the Literature on the Elasticity of Demand

    PubMed Central

    Pacula, Rosalie Liccardo; Lundberg, Russell

    2014-01-01

    Recent debates regarding liberalization of marijuana policies often rest on assumptions regarding the extent to which such policy changes would lead to a change in marijuana consumption and by whom. This paper reviews the economics literature assessing the responsiveness of consumption to changes in price and enforcement risk and explicitly considers how this responsiveness varies by different user groups. In doing so, it demonstrates how most of the research has examined responsiveness to prevalence of use, which is a composite of different user groups, rather than level of consumption among regular or heavy users, which represent the largest share of total quantities consumed. Thus, it is not possible to generate reliable estimates of the impact of liberalizing policies on either tax revenues or harms, as these outcomes are most directly influenced by the amounts consumed by regular or heavy users, not prevalence rates. PMID:25642015

  16. Accuracy analysis of TDRSS demand forecasts

    NASA Technical Reports Server (NTRS)

    Stern, Daniel C.; Levine, Allen J.; Pitt, Karl J.

    1994-01-01

    This paper reviews Space Network (SN) demand forecasting experience over the past 16 years and describes methods used in the forecasts. The paper focuses on the Single Access (SA) service, the most sought-after resource in the Space Network. Of the ten years of actual demand data available, only the last five years (1989 to 1993) were considered predictive due to the extensive impact of the Challenger accident of 1986. NASA's Space Network provides tracking and communications services to user spacecraft such as the Shuttle and the Hubble Space Telescope. Forecasting the customer requirements is essential to planning network resources and to establishing service commitments to future customers. The lead time to procure Tracking and Data Relay Satellites (TDRS's) requires demand forecasts ten years in the future a planning horizon beyond the funding commitments for missions to be supported. The long range forecasts are shown to have had a bias toward underestimation in the 1991 -1992 period. The trend of underestimation can be expected to be replaced by overestimation for a number of years starting with 1998. At that time demand from new missions slated for launch will be larger than the demand from ongoing missions, making the potential for delay the dominant factor. If the new missions appear as scheduled, the forecasts are likely to be moderately underestimated. The SN commitment to meet the negotiated customer's requirements calls for conservatism in the forecasting. Modification of the forecasting procedure to account for a delay bias is, therefore, not advised. Fine tuning the mission model to more accurately reflect the current actual demand is recommended as it may marginally improve the first year forecasting.

  17. DEMAND CONTROLLED VENTILATION AND CLASSROOM VENTILATION

    SciTech Connect

    Fisk, William J.; Mendell, Mark J.; Davies, Molly; Eliseeva, Ekaterina; Faulkner, David; Hong, Tienzen; Sullivan, Douglas P.

    2014-01-06

    This document summarizes a research effort on demand controlled ventilation and classroom ventilation. The research on demand controlled ventilation included field studies and building energy modeling. Major findings included: ? The single-location carbon dioxide sensors widely used for demand controlled ventilation frequently have large errors and will fail to effectively control ventilation rates (VRs).? Multi-location carbon dioxide measurement systems with more expensive sensors connected to multi-location sampling systems may measure carbon dioxide more accurately.? Currently-available optical people counting systems work well much of the time but have large counting errors in some situations. ? In meeting rooms, measurements of carbon dioxide at return-air grilles appear to be a better choice than wall-mounted sensors.? In California, demand controlled ventilation in general office spaces is projected to save significant energy and be cost effective only if typical VRs without demand controlled ventilation are very high relative to VRs in codes. Based on the research, several recommendations were developed for demand controlled ventilation specifications in the California Title 24 Building Energy Efficiency Standards.The research on classroom ventilation collected data over two years on California elementary school classrooms to investigate associations between VRs and student illness absence (IA). Major findings included: ? Median classroom VRs in all studied climate zones were below the California guideline, and 40percent lower in portable than permanent buildings.? Overall, one additional L/s per person of VR was associated with 1.6percent less IA. ? Increasing average VRs in California K-12 classrooms from the current average to the required level is estimated to decrease IA by 3.4percent, increasing State attendance-based funding to school districts by $33M, with $6.2 M in increased energy costs. Further VR increases would provide additional benefits

  18. Effects of elastic indenter deformation on spherical instrumented indentation tests: the reduced elastic modulus

    NASA Astrophysics Data System (ADS)

    Aida Rodríguez, Sara; Alcalá, Jorge; Martins Souza, Roberto

    2011-03-01

    Although the Hertz theory is not applicable in the analysis of the indentation of elastic-plastic materials, it is common practice to incorporate the concept of indenter/specimen combined modulus to consider indenter deformation. The appropriateness was assessed of the use of reduced modulus to incorporate the effect of indenter deformation in the analysis of the indentation with spherical indenters. The analysis based on finite element simulations considered four values of the ratio of the indented material elastic modulus to that of the diamond indenter, E/Ei (0, 0.04, 0.19, 0.39), four values of the ratio of the elastic reduced modulus to the initial yield strength, Er/Y (0, 10, 20, 100), and two values of the ratio of the indenter radius to maximum total displacement, R/δmax (3, 10). Indenter deformation effects are better accounted for by the reduced modulus if the indented material behaves entirely elastically. In this case, identical load-displacement (P - δ) curves are obtained with rigid and elastic spherical indenters for the same elastic reduced modulus. Changes in the ratio E/Ei , from 0 to 0.39, resulted in variations lower than 5% for the load dimensionless functions, lower than 3% in the contact area, Ac , and lower than 5% in the ratio H/Er . However, deformations of the elastic indenter made the actual radius of contact change, even in the indentation of elastic materials. Even though the load dimensionless functions showed only a little increase with the ratio E/Ei , the hardening coefficient and the yield strength could be slightly overestimated when algorithms based on rigid indenters are used. For the unloading curves, the ratio δe/δmax , where δe is the point corresponding to zero load of a straight line with slope S from the point (Pmax, δmax ), varied less than 5% with the ratio E/Ei . Similarly, the relationship between reduced modulus and the unloading indentation curve, expressed by Sneddon's equation, did not reveal the necessity

  19. Extreme stiffness hyperbolic elastic metamaterial for total transmission subwavelength imaging

    NASA Astrophysics Data System (ADS)

    Lee, Hyuk; Oh, Joo Hwan; Seung, Hong Min; Cho, Seung Hyun; Kim, Yoon Young

    2016-04-01

    Subwavelength imaging by metamaterials and extended work to pursue total transmission has been successfully demonstrated with electromagnetic and acoustic waves very recently. However, no elastic counterpart has been reported because earlier attempts suffer from considerable loss. Here, for the first time, we realize an elastic hyperbolic metamaterial lens and experimentally show total transmission subwavelength imaging with measured wave field inside the metamaterial lens. The main idea is to compensate for the decreased impedance in the perforated elastic metamaterial by utilizing extreme stiffness, which has not been independently actualized in a continuum elastic medium so far. The fabricated elastic lens is capable of directly transferring subwavelength information from the input to the output boundary. In the experiment, this intriguing phenomenon is confirmed by scanning the elastic structures inside the lens with laser scanning vibrometer. The proposed elastic metamaterial lens will bring forth significant guidelines for ultrasonic imaging techniques.

  20. Extreme stiffness hyperbolic elastic metamaterial for total transmission subwavelength imaging.

    PubMed

    Lee, Hyuk; Oh, Joo Hwan; Seung, Hong Min; Cho, Seung Hyun; Kim, Yoon Young

    2016-04-04

    Subwavelength imaging by metamaterials and extended work to pursue total transmission has been successfully demonstrated with electromagnetic and acoustic waves very recently. However, no elastic counterpart has been reported because earlier attempts suffer from considerable loss. Here, for the first time, we realize an elastic hyperbolic metamaterial lens and experimentally show total transmission subwavelength imaging with measured wave field inside the metamaterial lens. The main idea is to compensate for the decreased impedance in the perforated elastic metamaterial by utilizing extreme stiffness, which has not been independently actualized in a continuum elastic medium so far. The fabricated elastic lens is capable of directly transferring subwavelength information from the input to the output boundary. In the experiment, this intriguing phenomenon is confirmed by scanning the elastic structures inside the lens with laser scanning vibrometer. The proposed elastic metamaterial lens will bring forth significant guidelines for ultrasonic imaging techniques.

  1. Acoustic radiation force elasticity imaging in diagnostic ultrasound.

    PubMed

    Doherty, Joshua R; Trahey, Gregg E; Nightingale, Kathryn R; Palmeri, Mark L

    2013-04-01

    The development of ultrasound-based elasticity imaging methods has been the focus of intense research activity since the mid-1990s. In characterizing the mechanical properties of soft tissues, these techniques image an entirely new subset of tissue properties that cannot be derived with conventional ultrasound techniques. Clinically, tissue elasticity is known to be associated with pathological condition and with the ability to image these features in vivo; elasticity imaging methods may prove to be invaluable tools for the diagnosis and/or monitoring of disease. This review focuses on ultrasound-based elasticity imaging methods that generate an acoustic radiation force to induce tissue displacements. These methods can be performed noninvasively during routine exams to provide either qualitative or quantitative metrics of tissue elasticity. A brief overview of soft tissue mechanics relevant to elasticity imaging is provided, including a derivation of acoustic radiation force, and an overview of the various acoustic radiation force elasticity imaging methods.

  2. Extreme stiffness hyperbolic elastic metamaterial for total transmission subwavelength imaging

    PubMed Central

    Lee, Hyuk; Oh, Joo Hwan; Seung, Hong Min; Cho, Seung Hyun; Kim, Yoon Young

    2016-01-01

    Subwavelength imaging by metamaterials and extended work to pursue total transmission has been successfully demonstrated with electromagnetic and acoustic waves very recently. However, no elastic counterpart has been reported because earlier attempts suffer from considerable loss. Here, for the first time, we realize an elastic hyperbolic metamaterial lens and experimentally show total transmission subwavelength imaging with measured wave field inside the metamaterial lens. The main idea is to compensate for the decreased impedance in the perforated elastic metamaterial by utilizing extreme stiffness, which has not been independently actualized in a continuum elastic medium so far. The fabricated elastic lens is capable of directly transferring subwavelength information from the input to the output boundary. In the experiment, this intriguing phenomenon is confirmed by scanning the elastic structures inside the lens with laser scanning vibrometer. The proposed elastic metamaterial lens will bring forth significant guidelines for ultrasonic imaging techniques. PMID:27040762

  3. Competitive Facility Location with Random Demands

    NASA Astrophysics Data System (ADS)

    Uno, Takeshi; Katagiri, Hideki; Kato, Kosuke

    2009-10-01

    This paper proposes a new location problem of competitive facilities, e.g. shops and stores, with uncertain demands in the plane. By representing the demands for facilities as random variables, the location problem is formulated to a stochastic programming problem, and for finding its solution, three deterministic programming problems: expectation maximizing problem, probability maximizing problem, and satisfying level maximizing problem are considered. After showing that one of their optimal solutions can be found by solving 0-1 programming problems, their solution method is proposed by improving the tabu search algorithm with strategic vibration. Efficiency of the solution method is shown by applying to numerical examples of the facility location problems.

  4. Demand Response as a System Reliability Resource

    SciTech Connect

    Eto, Joseph H.; Lewis, Nancy Jo; Watson, David; Kiliccote, Sila; Auslander, David; Paprotny, Igor; Makarov, Yuri

    2012-12-31

    The Demand Response as a System Reliability Resource project consists of six technical tasks: • Task 2.1. Test Plan and Conduct Tests: Contingency Reserves Demand Response (DR) Demonstration—a pioneering demonstration of how existing utility load-management assets can provide an important electricity system reliability resource known as contingency reserve. • Task 2.2. Participation in Electric Power Research Institute (EPRI) IntelliGrid—technical assistance to the EPRI IntelliGrid team in developing use cases and other high-level requirements for the architecture. • Task 2.3. Research, Development, and Demonstration (RD&D) Planning for Demand Response Technology Development—technical support to the Public Interest Energy Research (PIER) Program on five topics: Sub-task 1. PIER Smart Grid RD&D Planning Document; Sub-task 2. System Dynamics of Programmable Controllable Thermostats; Sub-task 3. California Independent System Operator (California ISO) DR Use Cases; Sub-task 4. California ISO Telemetry Requirements; and Sub-task 5. Design of a Building Load Data Storage Platform. • Task 2.4. Time Value of Demand Response—research that will enable California ISO to take better account of the speed of the resources that it deploys to ensure compliance with reliability rules for frequency control. • Task 2.5. System Integration and Market Research: Southern California Edison (SCE)—research and technical support for efforts led by SCE to conduct demand response pilot demonstrations to provide a contingency reserve service (known as non-spinning reserve) through a targeted sub-population of aggregated residential and small commercial customers enrolled in SCE’s traditional air conditioning (AC) load cycling program, the Summer Discount Plan. • Task 2.6. Demonstrate Demand Response Technologies: Pacific Gas and Electric (PG&E)—research and technical support for efforts led by PG&E to conduct a demand response pilot demonstration to provide non

  5. Three Essays on National Oil Company Efficiency, Energy Demand and Transportation

    NASA Astrophysics Data System (ADS)

    Eller, Stacy L.

    This dissertation is composed of three separate essays in the field of energy economics. In the first paper, both data envelopment analysis and stochastic production frontier estimation are employed to provide empirical evidence on the revenue efficiency of national oil companies (NOCs) and private international oil companies (IOCs). Using a panel of 80 oil producing firms, the analysis suggests that NOCs are generally less efficient at generating revenue from a given resource base than IOCs, with some exceptions. Due to differing firm objectives, however, structural and institutional features may help explain much of the inefficiency. The second paper analyzes the relationship between economic development and the demand for energy. Energy consumption is modeled using panel data from 1990 to 2004 for 50 countries spanning all levels of development. We find the relationship between energy consumption and economic development corresponds to the structure of aggregate output and the nature of derived demand for electricity and direct-use fuels in each sector. Notably, the evidence of non-constant income elasticity of demand is much greater for electricity demand than for direct-use fuel consumption. In addition, we show that during periods of rapid economic development, one in which the short-term growth rate exceeds the long-run average, an increase in aggregate output is met by less energy-efficient capital. This is a result of capital being fixed in the short-term. As additional, more efficient capital stock is added to the production process, the short-term increase in energy intensity will diminish. In the third essay, we develop a system of equations to estimate a model of motor vehicle fuel consumption, vehicle miles traveled and implied fuel efficiency for the 67 counties of the State of Florida from 2001 to 2008. This procedure allows us to decompose the factors of fuel demand into elasticities of vehicle driving demand and fuel efficiency. Particular

  6. Installation and Commissioning Automated Demand Response Systems

    SciTech Connect

    Global Energy Partners; Pacific Gas and Electric Company; Kiliccote, Sila; Kiliccote, Sila; Piette, Mary Ann; Wikler, Greg; Prijyanonda, Joe; Chiu, Albert

    2008-04-21

    Demand Response (DR) can be defined as actions taken to reduce electric loads when contingencies, such as emergencies and congestion, occur that threaten supply-demand balance, or market conditions raise supply costs. California utilities have offered price and reliability DR based programs to customers to help reduce electric peak demand. The lack of knowledge about the DR programs and how to develop and implement DR control strategies is a barrier to participation in DR programs, as is the lack of automation of DR systems. Most DR activities are manual and require people to first receive notifications, and then act on the information to execute DR strategies. Levels of automation in DR can be defined as follows. Manual Demand Response involves a labor-intensive approach such as manually turning off or changing comfort set points at each equipment switch or controller. Semi-Automated Demand Response involves a pre-programmed demand response strategy initiated by a person via centralized control system. Fully-Automated Demand Response does not involve human intervention, but is initiated at a home, building, or facility through receipt of an external communications signal. The receipt of the external signal initiates pre-programmed demand response strategies. We refer to this as Auto-DR (Piette et. al. 2005). Auto-DR for commercial and industrial facilities can be defined as fully automated DR initiated by a signal from a utility or other appropriate entity and that provides fully-automated connectivity to customer end-use control strategies. One important concept in Auto-DR is that a homeowner or facility manager should be able to 'opt out' or 'override' a DR event if the event comes at time when the reduction in end-use services is not desirable. Therefore, Auto-DR is not handing over total control of the equipment or the facility to the utility but simply allowing the utility to pass on grid related information which then triggers facility defined and programmed

  7. Scattering of time-harmonic elastic waves by an elastic inclusion with quadratic nonlinearity.

    PubMed

    Tang, Guangxin; Jacobs, Laurence J; Qu, Jianmin

    2012-04-01

    This paper considers the scattering of a plane, time-harmonic wave by an inclusion with heterogeneous nonlinear elastic properties embedded in an otherwise homogeneous linear elastic solid. When the inclusion and the surrounding matrix are both isotropic, the scattered second harmonic fields are obtained in terms of the Green's function of the surrounding medium. It is found that the second harmonic fields depend on two independent acoustic nonlinearity parameters related to the third order elastic constants. Solutions are also obtained when these two acoustic nonlinearity parameters are given as spatially random functions. An inverse procedure is developed to obtain the statistics of these two random functions from the measured forward and backscattered second harmonic fields.

  8. Viscous-elastic dynamics of power-law fluids within an elastic cylinder

    NASA Astrophysics Data System (ADS)

    Gat, Amir; Boyko, Evgeniy; Bercovici, Moran

    2016-11-01

    We study the fluid-structure interaction dynamics of non-Newtonian flow through a slender linearly elastic cylinder at the creeping flow regime. Specifically, considering power-law fluids and applying the thin shell approximation for the elastic cylinder, we obtain a non-homogeneous p-Laplacian equation governing the viscous-elastic dynamics. We obtain exact solutions for the pressure and deformation fields for various initial and boundary conditions, for both shear thinning and shear thickening fluids. In particular, impulse or a step in inlet pressure yield self-similar solutions, which exhibit a compactly supported propagation front solely for shear thinning fluids. Applying asymptotic expansions, we provide approximations for weakly non-Newtonian behavior showing good agreement with the exact solutions sufficiently far from the front.

  9. Characterization of nonlinear elasticity and elastic instability in single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Xiao, Tan; Xu, Xiaojing; Liao, Kin

    2004-06-01

    Nonlinear elastic properties and elastic instability of single-walled carbon nanotubes (SWNTs) under large-scale axial compression were investigated by molecular simulations using the second-generation Brenner potential. It was found that the energy changes of the nanotube can be closely fitted by a cubic function of applied strains. Therefore the in-plane stiffness C of the nanotube is linearly dependent on the strain. It shows that SWNTs harden under compression but soften in tension. At large strain, C is also sensitive to chirality and diameters of nanotubes when these are small. The critical strains of compressed nanotubes are inversely proportional to their diameters on the condition that local buckling occurs in simulations, which can be properly predicted by continuum elasticity theory if the effective thickness is known.

  10. Energy technologies and their impact on demand

    SciTech Connect

    Drucker, H.

    1995-06-01

    Despite the uncertainties, energy demand forecasts must be made to guide government policies and public and private-sector capital investment programs. Three principles can be identified in considering long-term energy prospects. First energy demand will continue to grow, driven by population growth, economic development, and the current low per capita energy consumption in developing countries. Second, energy technology advancements alone will not solve the problem. Energy-efficient technologies, renewable resource technologies, and advanced electric power technologies will all play a major role but will not be able to keep up with the growth in world energy demand. Third, environmental concerns will limit the energy technology choices. Increasing concern for environmental protection around the world will restrict primarily large, centralized energy supply facilities. The conclusion is that energy system diversity is the only solution. The energy system must be planned with consideration of both supply and demand technologies, must not rely on a single source of energy, must take advantage of all available technologies that are specially suited to unique local conditions, must be built with long-term perspectives, and must be able to adapt to change.

  11. Posing Cognitively Demanding Tasks to All Students

    ERIC Educational Resources Information Center

    Lambert, Rachel; Stylianou, Despina A.

    2013-01-01

    Cognitively demanding tasks (CDT) (Stein et al. 2000) are necessary for the development of students' mathematical reasoning skills. Research is unequivocal on the importance of giving students opportunities to engage in such tasks. Although current reform efforts call for mathematics learning for "all" students, learners who…

  12. Multicultural Schools and New Demands on Leadership

    ERIC Educational Resources Information Center

    Andersen, Fred Carlo

    2014-01-01

    The purpose of this study is to explore the Norwegian Government's expectations pertaining to new demands on leadership expressed in policy documents with regard to a multicultural society. Data from seven government's white papers were thematically analyzed with regard to knowledge, skills and attitudes. The study is framed within a theoretical…

  13. Assessing Demand for Graduate and Professional Programs.

    ERIC Educational Resources Information Center

    Syverson, Peter D.

    1996-01-01

    Graduate education is entering an era of market segmentation, varying student demand, and changing requirements from employers, meaning graduate students will assess graduate opportunities differently and institutions will assess programs differently. The traditional view of graduate study as preparation for a research or teaching career and…

  14. Money Demand and Risk: A Classroom Experiment

    ERIC Educational Resources Information Center

    Ewing, Bradley T.; Kruse, Jamie B.; Thompson, Mark A.

    2004-01-01

    The authors describe a classroom experiment that motivates student understanding of behavior toward risk and its effect on money demand. In this experiment, students are endowed with an income stream that they can allocate between a risk-free fund and a risky fund. Changes in volatility are represented by mean-preserving changes in the variance of…

  15. Aviation Frontiers: On-Demand Aircraft

    NASA Technical Reports Server (NTRS)

    Moore, Mark D.

    2010-01-01

    Throughout the 20th Century, NASA has defined the forefront of aeronautical technology, and the aviation industry owes much of its prosperity to this knowledge and technology. In recent decades, centralized aeronautics has become a mature discipline, which raises questions concerning the future aviation innovation frontiers. Three transformational aviation capabilities, bounded together by the development of a Free Flight airspace management system, have the potential to transform 21st Century society as profoundly as civil aviation transformed the 20th Century. These mobility breakthroughs will re-establish environmental sustainable centralized aviation, while opening up latent markets for civil distributed sensing and on-demand rural and regional transportation. Of these three transformations, on-demand aviation has the potential to have the largest market and productivity improvement to society. The information system revolution over the past 20 years shows that vehicles lead, and the interconnecting infrastructure to make them more effective follows; that is, unless on-demand aircraft are pioneered, a distributed Air Traffic Control system will likely never be established. There is no single technology long-pole that will enable on-demand vehicle solutions. However, fully digital aircraft that include electric propulsion has the potential to be a multi-disciplinary initiator of solid state technologies that can provide order of magnitude improvements in the ease of use, safety/reliability, community and environmental friendliness, and affordability.

  16. Education and the Demand for Emancipation

    ERIC Educational Resources Information Center

    Skarpenes, Ove

    2014-01-01

    This paper puts forward the hypothesis that in recent decades, pupils of schools in the western world have been given a new form of individuality. This construction has been nourished by both the demand for emancipation as it was expressed in the critical sociology of education (and pedagogy) and by the neoliberal turn in education policy. It…

  17. Demand management implementation in Southeast Asia

    SciTech Connect

    Tanaboriboon, Y.

    1995-12-31

    The need to apply transportation system management, to developing countries is urgent. Attempts to alleviate severe traffic congestion in their metropolises have so far failed to provide adequate solutions. The countries are faced with many difficulties because of the lack of sufficient financial resources together with their complex internal administrative and political problems. They are incapable of providing sufficient road space to cope with the escalating demand in private automobiles. This has led to excessive delays in urban traveling, environmental pollution problems, decline of road-based public transit services and deterioration of the quality of life in these metropolises. Demand management, in use for decades in the Western world, has also been recognized in Singapore`s famous area licensing scheme (ALS) making other Southeast Asian Metropolises aware of its advantages as an alternative in solving their chaotic traffic problems. However, realization is far different from implementation and still many metropolises are not able to apply the technique. Singapore and Thailand, two leaders among many other Southeast Asian regions in economics, tourism, trade and industry handle their problems far differently, especially the traffic congestion problem. While a number of demand management schemes have been implemented successfully in Singapore since 1975, Bangkok is still struggling to implement such measures to alleviate severe traffic congestion problems. This article intends to high light the successful practices and unsuccessful attempts of demand management techniques applied in Singapore and Bangkok.

  18. University Transformation: New Demands and Coping Strategies

    ERIC Educational Resources Information Center

    Chidindi, Joseph

    2012-01-01

    University education system is undergoing transformation requirements particularly in the developing world. The demands require adaptation to the prevailing circumstances hence the need for relevant strategies for universities. Issues such as institutional profiles, organizational structure and work integration, research activities, and funding…

  19. Market Demand for Special Education Faculty

    ERIC Educational Resources Information Center

    Montrosse, Bianca Elizabeth; Young, Christopher J.

    2012-01-01

    Since 1988, researchers have monitored the extent and severity of the chronic special education (SE) faculty shortage. The present study sought to add to this knowledge base by (a) gathering data on the supply and demand of leadership personnel in SE since the "2001 Faculty Shortage Study"; (b) combining and comparing these data with other sources…

  20. Educational Technology on Demand: It's about Time!

    ERIC Educational Resources Information Center

    Weir, Bob; Mickool, Rick; Hitch, Leslie

    2006-01-01

    Today's incoming freshmen, born in 1988, have never known a time when the Internet and personal computers were not ubiquitous. They expect "what I want, when I need it, wherever I happen to be, on whatever workstation I have available." Many industries already meet this demand--entertainment (legal or pirated), cable TV, digital video recorders,…