Growing Up and Cleaning Up: The Environmental Kuznets Curve Redux.
Franklin, Rachel S; Ruth, Matthias
2012-01-01
Borrowing from the Kuznets curve literature, researchers have coined the term "environmental Kuznets curve" or EKC to characterize the relationship between pollution levels and income: pollution levels will increase with income but some threshold of income will eventually be reached, beyond which pollution levels will decrease. The link between the original Kuznets curve, which posited a similar relationship between income and inequality, and its pollution-concerned offspring lies primarily with the shape of both curves (an upside-down U) and the central role played by income change. Although the EKC literature has burgeoned over the past several years, few concrete conclusions have been drawn, the main themes of the literature have remained constant, and no consensus has been reached regarding the existence of an environmental Kuznets curve. EKC research has used a variety of types of data and a range of geographical units to examine the effects of income levels on pollution. Changes in pollution levels might also be at least partly explained by countries' position in the demographic transition and their general population structure, however little research has included this important aspect in the analysis. In addition, few analyses confine themselves to an evaluation for one country of the long-term relationship between income and pollution. Using United States CO2 emissions as well as demographic, employment, trade and energy price data, this paper seeks to highlight the potential impact of population and economic structure in explaining the relationship between income and pollution levels. PMID:25214678
Growing Up and Cleaning Up: The Environmental Kuznets Curve Redux
Franklin, Rachel S.; Ruth, Matthias
2014-01-01
Borrowing from the Kuznets curve literature, researchers have coined the term “environmental Kuznets curve” or EKC to characterize the relationship between pollution levels and income: pollution levels will increase with income but some threshold of income will eventually be reached, beyond which pollution levels will decrease. The link between the original Kuznets curve, which posited a similar relationship between income and inequality, and its pollution-concerned offspring lies primarily with the shape of both curves (an upside-down U) and the central role played by income change. Although the EKC literature has burgeoned over the past several years, few concrete conclusions have been drawn, the main themes of the literature have remained constant, and no consensus has been reached regarding the existence of an environmental Kuznets curve. EKC research has used a variety of types of data and a range of geographical units to examine the effects of income levels on pollution. Changes in pollution levels might also be at least partly explained by countries’ position in the demographic transition and their general population structure, however little research has included this important aspect in the analysis. In addition, few analyses confine themselves to an evaluation for one country of the long-term relationship between income and pollution. Using United States CO2 emissions as well as demographic, employment, trade and energy price data, this paper seeks to highlight the potential impact of population and economic structure in explaining the relationship between income and pollution levels. PMID:25214678
Economic growth and energy regulation in the environmental Kuznets curve.
Lorente, Daniel Balsalobre; Álvarez-Herranz, Agustín
2016-08-01
This study establishes the existence of a pattern of behavior, between economic growth and environmental degradation, consistent with the environmental Kuznets curve (EKC) hypothesis for 17 Organization for Economic Cooperation and Development (OECD) countries between 1990 and 2012. Based on this EKC pattern, it shows that energy regulation measures help reduce per capita greenhouse gas (GHG) emissions. To validate this hypothesis, we also add the explanatory variables: renewable energy promotion, energy innovation processes, and the suppression effect of income level on the contribution of renewable energy sources to total energy consumption. It aims to be a tool for decision-making regarding energy policy. This paper provides a two-stage econometric analysis of instrumental variables with the aim of correcting the existence of endogeneity in the variable GDP per capita, verifying that the instrumental variables used in this research are appropriate for our aim. To this end, it first makes a methodological contribution before incorporating additional variables associated with environmental air pollution into the EKC hypothesis and showing how they positively affect the explanation of the correction in the GHG emission levels. This study concludes that air pollution will not disappear on its own as economic growth increases. Therefore, it is necessary to promote energy regulation measures to reduce environmental pollution. PMID:27164892
Revisiting the environmental Kuznets curve hypothesis in a tourism development context.
de Vita, Glauco; Katircioglu, Salih; Altinay, Levent; Fethi, Sami; Mercan, Mehmet
2015-11-01
This study investigates empirically an extended version of the Environmental Kuznets Curve model that controls for tourism development. We find that international tourist arrivals into Turkey alongside income, squared income and energy consumption, cointegrate with CO2 emissions. Tourist arrivals, growth, and energy consumption exert a positive and significant impact on CO2 emissions in the long-run. Our results provide empirical support to EKC hypothesis showing that at exponential levels of growth, CO2 emissions decline. The findings suggest that despite the environmental degradation stemming from tourism development, policies aimed at environmental protection should not be pursued at the expense of tourism-led growth. PMID:26081781
Ozturk, Ilhan; Al-Mulali, Usama; Saboori, Behnaz
2016-01-01
The main objective of this study is to examine the environmental Kuznets curve (EKC) hypothesis by utilizing the ecological footprint as an environment indicator and GDP from tourism as the economic indicator. To achieve this goal, an environmental degradation model is established during the period of 1988-2008 for 144 countries. The results from the time series generalized method of moments (GMM) and the system panel GMM revealed that the number of countries that have a negative relationship between the ecological footprint and its determinants (GDP growth from tourism, energy consumption, trade openness, and urbanization) is more existent in the upper middle- and high-income countries. Moreover, the EKC hypothesis is more present in the upper middle- and high-income countries than the other income countries. From the outcome of this research, a number of policy recommendations were provided for the investigated countries. PMID:26408117
Wong, Yoon Loong Andrew; Lewis, Lynne
2013-12-15
The literature is flush with articles focused on estimating the Environmental Kuznets Curve (EKC) for various pollutants and various locations. Most studies have utilized air pollution variables; far fewer have utilized water quality variables, all with mixed results. We suspect that mixed evidence of the EKC stems from model and error specification. We analyze annual data for four water quality indicators, three of them previously unstudied - total phosphorus (TOTP), dissolved oxygen (DO), ammonium (NH4) and nitrites (NO2) - from the Lower Mekong Basin region to determine whether an Environmental Kuznets Curve (EKC) is evident for a transboundary river in a developing country and whether that curve is dependent on model specification and/or pollutant. We build upon previous studies by correcting for the problems of heteroskedasticity, serial correlation and cross-sectional dependence. Unlike multi-country EKC studies, we mitigate for potential distortion from pooling data across geographically heterogeneous locations by analyzing data drawn from proximate locations within a specific international river basin in Southeast Asia. We also attempt to identify vital socioeconomic determinants of water pollution by including a broad list of explanatory variables alongside the income term. Finally, we attempt to shed light on the pollution-income relationship as it pertains to trans-boundary water pollution by examining data from an international river system. We do not find consistent evidence of an EKC for any of the 4 pollutant indicators in this study, but find the results are entirely dependent on model and error specification as well as pollutant. PMID:24211570
Environmental costs and renewable energy: re-visiting the Environmental Kuznets Curve.
López-Menéndez, Ana Jesús; Pérez, Rigoberto; Moreno, Blanca
2014-12-01
The environmental costs of economic development have received increasing attention during the last years. According to the World Energy Outlook (2013) sustainable energy policies should be promoted in order to spur economic growth and environmental protection in a global context, particularly in terms of reducing greenhouse gas emissions that contribute to climate change. Within this framework, the European Union aims to achieve the "20-20-20" targets, including a 20% reduction in EU greenhouse gas emissions from 1990 levels, a raise in the share of EU energy consumption produced from renewable resources to 20% and a 20% improvement in the EU's energy efficiency. Furthermore, the EU "Energy Roadmap 2050" has been recently adopted as a basis for developing a long-term European energy framework, fighting against climate change through the implementation of energy efficiency measures and the reduction of emissions. This paper focuses on the European context and attempts to explain the impact of economic growth on CO2 emissions through the estimation of an Environmental Kuznets Curve (EKC) using panel data. Moreover, since energy seems to be at the heart of the environmental problem it should also form the core of the solution, and therefore we provide some extensions of the EKC by including renewable energy sources as explanatory variables in the proposed models. Our data sets are referred to the 27 countries of the European Union during the period 1996-2010. With this information, our empirical results provide some interesting evidence about the significant impacts of renewable energies on CO2 emissions, suggesting the existence of an extended EKC. PMID:25124789
Arbulú, Italo; Lozano, Javier; Rey-Maquieira, Javier
2015-12-01
The relationship between tourism growth and municipal solid waste (MSW) generation has been, until now, the subject of little research. This is puzzling since the tourism sector is an important MSW generator and, at the same time, is willing to avoid negative impacts from MSW mismanagement. This paper aims to provide tools for tourism and MSW management by assessing the effects of tourism volume, tourism quality and tourism specialization on MSW generation in the UE. This is done using the Environmental Kuznets Curve (EKC) framework. The study considers a panel data for 32 European economies in the 1997-2010 periods. Empirical results support the EKC hypothesis for MSW and shows that northern countries tend to have lower income elasticity than less developed countries; furthermore, results confirm a non-linear and significant effect of tourism arrivals, expenditure per tourist and tourism specialization on MSW generation. PMID:26294012
Mao, Chunlan; Zhai, Ningning; Yang, Jingchao; Feng, Yongzhong; Cao, Yanchun; Han, Xinhui; Ren, Guangxin; Yang, Gaihe; Meng, Qing-xiang
2013-01-01
This study applies the environmental Kuznets curve to test the relationship between the regional economic growth and the different types of agricultural nonpoint source pollution loads in the Ningxia Yellow River irrigation area by using the Johnes export coefficient method. Results show that the pollution load generated by crop cultivation and livestock-breeding industries in the Ningxia Yellow River irrigation area shows an inverted U-shaped feature; however, this feature is absent in living-sewage pollution load. Crop pollution has shown a decreasing trend since 1997 because of the increased per capita income of farmers. Livestock-breeding pollution load reached its turning point when the per capita income of farmers reached 8386.74 RMB. Therefore, an increase in the per capita income of farmers corresponds to an increase in the livestock-breeding pollution load in the Ningxia Yellow River irrigation area. PMID:24171160
Liu, Xiao-Hui; Wang, Wei-Liang; Lu, Shao-Yong; Wang, Yu-Fan; Ren, Zongming
2016-08-01
In Zaozhuang, economic development affects the discharge amount of industrial wastewater, chemical oxygen demand (COD), and ammonia nitrogen (NH3-N). To reveal the trend of water environmental quality related to the economy in Zaozhuang, this paper simulated the relationships between industrial wastewater discharge, COD, NH3-N load, and gross domestic product (GDP) per capita for Zaozhuang (2002-2012) using environmental Kuznets curve (EKC) models. The results showed that the added value of industrial GDP, the per capita GDP, and wastewater emission had average annual growth rates of 16.62, 16.19, and 17.89 %, respectively, from 2002 to 2012, while COD and NH3-N emission in 2012, compared with 2002, showed average annual decreases of 10.70 and 31.12 %, respectively. The export of EKC models revealed that industrial wastewater discharge had a typical inverted-U-shaped relationship with per capita GDP. However, both COD and NH3-N showed the binding curve of the left side of the "U" curve and left side U-shaped curve. The economy in Zaozhuang had been at the "fast-growing" stage, with low environmental pollution according to the industrial pollution level. In recent years, Zaozhuang has abated these heavy-pollution industries emphatically, so pollutants have been greatly reduced. Thus, Zaozhuang industrial wastewater treatment has been quite effective, with water quality improved significantly. The EKC models provided scientific evidence for estimating industrial wastewater discharge, COD, and NH3-N load as well as their changeable trends for Zaozhuang from an economic perspective. PMID:27155838
Selecting CO2 Sources for CO2 Utilization by Environmental-Merit-Order Curves.
von der Assen, Niklas; Müller, Leonard J; Steingrube, Annette; Voll, Philip; Bardow, André
2016-02-01
Capture and utilization of CO2 as alternative carbon feedstock for fuels, chemicals, and materials aims at reducing greenhouse gas emissions and fossil resource use. For capture of CO2, a large variety of CO2 sources exists. Since they emit much more CO2 than the expected demand for CO2 utilization, the environmentally most favorable CO2 sources should be selected. For this purpose, we introduce the environmental-merit-order (EMO) curve to rank CO2 sources according to their environmental impacts over the available CO2 supply. To determine the environmental impacts of CO2 capture, compression and transport, we conducted a comprehensive literature study for the energy demands of CO2 supply, and constructed a database for CO2 sources in Europe. Mapping these CO2 sources reveals that CO2 transport distances are usually small. Thus, neglecting transport in a first step, we find that environmental impacts are minimized by capturing CO2 first from chemical plants and natural gas processing, then from paper mills, power plants, and iron and steel plants. In a second step, we computed regional EMO curves considering transport and country-specific impacts for energy supply. Building upon regional EMO curves, we identify favorable locations for CO2 utilization with lowest environmental impacts of CO2 supply, so-called CO2 oases. PMID:26752014
Measurement error in environmental epidemiology and the shape of exposure-response curves.
Rhomberg, Lorenz R; Chandalia, Juhi K; Long, Christopher M; Goodman, Julie E
2011-09-01
Both classical and Berkson exposure measurement errors as encountered in environmental epidemiology data can result in biases in fitted exposure-response relationships that are large enough to affect the interpretation and use of the apparent exposure-response shapes in risk assessment applications. A variety of sources of potential measurement error exist in the process of estimating individual exposures to environmental contaminants, and the authors review the evaluation in the literature of the magnitudes and patterns of exposure measurement errors that prevail in actual practice. It is well known among statisticians that random errors in the values of independent variables (such as exposure in exposure-response curves) may tend to bias regression results. For increasing curves, this effect tends to flatten and apparently linearize what is in truth a steeper and perhaps more curvilinear or even threshold-bearing relationship. The degree of bias is tied to the magnitude of the measurement error in the independent variables. It has been shown that the degree of bias known to apply to actual studies is sufficient to produce a false linear result, and that although nonparametric smoothing and other error-mitigating techniques may assist in identifying a threshold, they do not guarantee detection of a threshold. The consequences of this could be great, as it could lead to a misallocation of resources towards regulations that do not offer any benefit to public health. PMID:21823979
The Kuznets Curve of Education: A Global Perspective on Education Inequalities. CEE DP 116
ERIC Educational Resources Information Center
Morrison, Christian; Murtin, Fabrice
2010-01-01
Education is recognized to be a key factor of economic development, not only giving access to technological progress as emphasized by the Schumpeterian growth theory, but also entailing numerous social externalities such as the demographic transition (Murtin, 2009) or democratization (Murtin and Wacziarg, 2010). If the evolution of world…
Unthank, Michael D.; Newson, Jeremy K.; Williamson, Tanja N.; Nelson, Hugh L.
2012-01-01
Flow- and load-duration curves were constructed from the model outputs of the U.S. Geological Survey's Water Availability Tool for Environmental Resources (WATER) application for streams in Kentucky. The WATER application was designed to access multiple geospatial datasets to generate more than 60 years of statistically based streamflow data for Kentucky. The WATER application enables a user to graphically select a site on a stream and generate an estimated hydrograph and flow-duration curve for the watershed upstream of that point. The flow-duration curves are constructed by calculating the exceedance probability of the modeled daily streamflows. User-defined water-quality criteria and (or) sampling results can be loaded into the WATER application to construct load-duration curves that are based on the modeled streamflow results. Estimates of flow and streamflow statistics were derived from TOPographically Based Hydrological MODEL (TOPMODEL) simulations in the WATER application. A modified TOPMODEL code, SDP-TOPMODEL (Sinkhole Drainage Process-TOPMODEL) was used to simulate daily mean discharges over the period of record for 5 karst and 5 non-karst watersheds in Kentucky in order to verify the calibrated model. A statistical evaluation of the model's verification simulations show that calibration criteria, established by previous WATER application reports, were met thus insuring the model's ability to provide acceptably accurate estimates of discharge at gaged and ungaged sites throughout Kentucky. Flow-duration curves are constructed in the WATER application by calculating the exceedence probability of the modeled daily flow values. The flow-duration intervals are expressed as a percentage, with zero corresponding to the highest stream discharge in the streamflow record. Load-duration curves are constructed by applying the loading equation (Load = Flow*Water-quality criterion) at each flow interval.
The environmental impact of poverty: evidence from firewood collection in rural Nepal.
Baland, Jean-Marie; Bardhan, Pranab; Das, Sanghamitra; Mookherjee, Dilip; Sarkar, Rinki
2010-01-01
We investigate determinants of household firewood collection in rural Nepal, using 1995-96 and 2002-3 World Bank Living Standards Measurement Survey (LSMS) data. We incorporate village fixed effects, endogenous censoring, measurement error in living standards and heterogeneous effects of different household assets. We find no evidence in favor of the poverty-environment hypothesis. The evidence for the environmental Kuznets curve depends on the precise measure of living standards and time period studied. Firewood collections fall with a transition to modern occupations and rise with increasing population and household division. The local interhousehold collection externality is negligible, indicating that policy interventions are justified only by ecological considerations or nonlocal spillovers. PMID:20821892
Application of environmentally-corrected fatigue curves to nuclear power plant components
Ware, A.G.; Morton, D.K.; Nitzel, M.E.
1996-06-01
Recent test data indicate that the effects of the light water reactor (LWR) environment could significantly reduce the fatigue resistance of materials used in the reactor coolant pressure boundary components of operating nuclear power plants. Argonne National Laboratory has developed interim fatigue curves based on test data simulating LWR conditions, and published them in NUREG/CR-5999. In order to assess the significance of these interim fatigue curves, fatigue evaluations of a sample of the components in the reactor coolant pressure boundary of LWRs were performed. The sample consists of components from facilities designed by each of the four US nuclear steam supply system vendors. For each facility, six locations were studied including two locations on the reactor pressure vessel. In addition, there are older vintage plants where components of the reactor coolant pressure boundary were designed to codes that did not require an explicit fatigue analysis of the components. In order to assess the fatigue resistance of the older vintage plants, an evaluation was also conducted on selected components of three of these plants. This paper discusses the insights gained from the application of the interim fatigue curves to components of seven operating nuclear power plants.
Forbes, Thomas P; Najarro, Marcela
2016-07-21
The discriminative potential of an ion mobility spectrometer (IMS) for trace detection of illicit narcotics relative to environmental background was investigated with a receiver operating characteristic (ROC) curve framework. The IMS response of cocaine, heroin, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), and Δ(9)-tetrahydro-cannabinol (THC) was evaluated against environmental background levels derived from the screening of incoming delivery vehicles at a federal facility. Over 20 000 samples were collected over a multiyear period under two distinct sets of instrument operating conditions, a baseline mode and an increased desorption/drift tube temperature and sampling time mode. ROC curves provided a quantifiable representation of the interplay between sensitivity (true positive rate, TPR) and specificity (1 - false positive rate, FPR). A TPR of 90% and minimized FPR were targeted as the detection limits of IMS for the selected narcotics. MDMA, THC, and cocaine demonstrated single nanogram sensitivity at 90% TPR and <10% FPR, with improvements to both MDMA and cocaine in the elevated temperature/increased sampling mode. Detection limits in the tens of nanograms with poor specificity (FPR ≈ 20%) were observed for methamphetamine and heroin under baseline conditions. However, elevating the temperature reduced the background in the methamphetamine window, drastically improving its response (90% TPR and 3.8% FPR at 1 ng). On the contrary, the altered mode conditions increased the level of background for THC and heroin, partially offsetting observed enhancements to desorption. The presented framework demonstrated the significant effect environmental background distributions have on sensitivity and specificity. PMID:27206280
Not Available
1987-01-01
We tested a Harshaw Model 4000 TLD Reader in the Sandia Environmental TLD Program. An extra set of LiF TLD-700 chips were prepared for each field location and calibration level. At the end of quarter one, half of the TLDs were read on the Model 4000 and the other half were read on our standard Harshaw Model 2000. This presentation compares the results of the two systems. The Model 4000 results are reported for two regions of interest and for background subtraction using Harshaw Glow Curve Deconvolution Software.
Kätelhön, Arne; von der Assen, Niklas; Suh, Sangwon; Jung, Johannes; Bardow, André
2015-07-01
The environmental costs and benefits of introducing a new technology depend not only on the technology itself, but also on the responses of the market where substitution or displacement of competing technologies may occur. An internationally accepted method taking both technological and market-mediated effects into account, however, is still lacking in life cycle assessment (LCA). For the introduction of a new technology, we here present a new approach for modeling the environmental impacts within the framework of LCA. Our approach is motivated by consequential life cycle assessment (CLCA) and aims to contribute to the discussion on how to operationalize consequential thinking in LCA practice. In our approach, we focus on new technologies producing homogeneous products such as chemicals or raw materials. We employ the industry cost-curve (ICC) for modeling market-mediated effects. Thereby, we can determine substitution effects at a level of granularity sufficient to distinguish between competing technologies. In our approach, a new technology alters the ICC potentially replacing the highest-cost producer(s). The technologies that remain competitive after the new technology's introduction determine the new environmental impact profile of the product. We apply our approach in a case study on a new technology for chlor-alkali electrolysis to be introduced in Germany. PMID:26061620
Evaluating the Relative Environmental Impact of Countries
Bradshaw, Corey J. A.; Giam, Xingli; Sodhi, Navjot S.
2010-01-01
Environmental protection is critical to maintain ecosystem services essential for human well-being. It is important to be able to rank countries by their environmental impact so that poor performers as well as policy ‘models’ can be identified. We provide novel metrics of country-specific environmental impact ranks – one proportional to total resource availability per country and an absolute (total) measure of impact – that explicitly avoid incorporating confounding human health or economic indicators. Our rankings are based on natural forest loss, habitat conversion, marine captures, fertilizer use, water pollution, carbon emissions and species threat, although many other variables were excluded due to a lack of country-specific data. Of 228 countries considered, 179 (proportional) and 171 (absolute) had sufficient data for correlations. The proportional index ranked Singapore, Korea, Qatar, Kuwait, Japan, Thailand, Bahrain, Malaysia, Philippines and Netherlands as having the highest proportional environmental impact, whereas Brazil, USA, China, Indonesia, Japan, Mexico, India, Russia, Australia and Peru had the highest absolute impact (i.e., total resource use, emissions and species threatened). Proportional and absolute environmental impact ranks were correlated, with mainly Asian countries having both high proportional and absolute impact. Despite weak concordance among the drivers of environmental impact, countries often perform poorly for different reasons. We found no evidence to support the environmental Kuznets curve hypothesis of a non-linear relationship between impact and per capita wealth, although there was a weak reduction in environmental impact as per capita wealth increases. Using structural equation models to account for cross-correlation, we found that increasing wealth was the most important driver of environmental impact. Our results show that the global community not only has to encourage better environmental performance in less
Okada, Mika; Kawano, Kimiko; Kura, Fumiaki; Amemura-Maekawa, Junko; Watanabe, Haruo; Yagita, Kenji; Endo, Takuro; Suzuki, Sen
2005-06-01
In July 2002, a large outbreak of legionellosis occurred in a bathhouse with spa facilities in Miyazaki Prefecture. Two hundred-ninety-five patients (including suspected cases) that had pneumonia and/or symptoms of fever, cough and so forth were reported; 37% of them were hospitalized and seven people died. In environmental investigations, Legionella pneumophila serogroups (SGs) land 8, L. dumoffii, L. londiniensis, some other Legionella species and many kinds of amoeba were isolated from 55 samples of bathtub water, tank water, filters and so forth in the spa facilities. The dominant isolates from the bathtab waters belonged to L. londiniensis, L. dumoffii and L. pneumophila SG1, and their maximum concentrations were 1.5 x 10(6), 5.2 x 10(5) and 1.6 x 10(5) cfu/100 mL, respectively. L. pneumophila SG1 strains isolated from bathtub water, tank water, filters and sputa of patients showed a indistinguishable DNA fingerprint pattern by pulsed-field gel electrophoresis (PFGE), confirming that the source of infection was the spa water. Our study indicate that spas may be a significant health hazard if hygienic management fails. PMID:16022473
Angeles-Hernandez, J. C.; Albarran-Portillo, B.; Gomez Gonzalez, A. V.; Pescador Salas, N.; Gonzalez-Ronquillo, M.
2013-01-01
The objective of this study was to compare the goodness of fit of four lactation curve models: Wood’s Gamma model (WD), Wilmink (WL), and Pollott’s multiplicative two (POL2) and three parameters (POL3) and to determine the environmental factors affecting the complete lactation curve of F1 dairy sheep under organic management. A total of 5,382 weekly milk yields records from 150 ewes, under organic management were used. Residual mean square (RMS), determination coefficients (R2), and correlation (r) analysis were used as an indicator of goodness of fit for each model. WL model best fitted the lactation curves as indicated by the lower RMS values (0.019), followed by WD (0.023), POL2 (0.025) and POL3 (0.029). The four models provided total milk yield (TMY) estimations that were highly correlated (0.93 to 0.97) with observed TMY (89.9 kg). The four models under estimated peak yield (PY), whereas POL2 and POL3 gave nearer peak time lactation estimations. Ewes lambing in autumn had higher TMY and showed a typical curve shape. Higher TMY were recorded in second and third lambing. Season of lambing, number of lambing and type of lambing had a great influenced over TMY shaping the complete lactation curve of F1 dairy sheep. In general terms WL model showed the best fit to the F1 dairy sheep lactation curve under organic management. PMID:25049892
Concentration Response Curve for Ozone related Mortality at High Concentrations Ana G. Rappold, James Crooks, Lucas M. Neas Background Rising temperatures and decreased global circulation in the upcoming decades are expected to have a detrimental impact on air quality, particular...
Essays in environmental economics
NASA Astrophysics Data System (ADS)
Bartz-Marvez, Sherry L.
This body of work contributes to the literature on two current topics in environmental economics: (1) the relationship between economic development and environmental degradation; and (2) the effectiveness of mandatory information disclosure as a regulatory instrument. For the first topic, we link theoretical and empirical Environmental Kuznets Curve research by using calibration and simulation to test a growth model with environmental quality as a normal good and emissions as a factor of production. We use U.S. macroeconomic, emissions and compliance data to calibrate parameters representing preferences for environmental quality and marginal abatement costs. We simulate the model starting from a less-developed initial condition and compare the predicted pollution-income relationship with that in the data. Our results are mixed. Some support exists for the theory that an inverted U-shape results from a corner solution in which less developed countries do not abate pollution. However, pollution peaks at a level of per capita income which is much lower than that observed in the U.S. data. For the second topic, we study the effectiveness of mandatory information disclosure as environmental regulation. Community-right-to-know programs such as the EPA's Toxic Release Inventory (TRI) use mandatory information disclosure to "shame" dirty firms into reducing emissions. The idea is that the public---armed with previously unavailable emissions information---will pressure firms with higher-than-expected emissions to "clean-up." We use the electricity industry to study the impact of price-and-entry deregulation on the effectiveness of the TRI. Using event studies, we find that, on average, utilities experience losses in firm value immediately following TRI announcements. Using panel regressions, we show that toxic emissions released in regulated states are associated with decreases in firm value while those released in deregulated states are associated with increases in firm
Riggs, H.C.
1968-01-01
This manual describes graphical and mathematical procedures for preparing frequency curves from samples of hydrologic data. It also discusses the theory of frequency curves, compares advantages of graphical and mathematical fitting, suggests methods of describing graphically defined frequency curves analytically, and emphasizes the correct interpretations of a frequency curve.
ERIC Educational Resources Information Center
Rousseau, Ronald
1994-01-01
Discussion of informetric distributions shows that generalized Leimkuhler functions give proper fits to a large variety of Bradford curves, including those exhibiting a Groos droop or a rising tail. The Kolmogorov-Smirnov test is used to test goodness of fit, and least-square fits are compared with Egghe's method. (Contains 53 references.) (LRW)
ERIC Educational Resources Information Center
Yates, Robert C.
This volume, a reprinting of a classic first published in 1952, presents detailed discussions of 26 curves or families of curves, and 17 analytic systems of curves. For each curve the author provides a historical note, a sketch or sketches, a description of the curve, a discussion of pertinent facts, and a bibliography. Depending upon the curve,…
Standard Mastery Curves and Skew Curves.
ERIC Educational Resources Information Center
Warries, Egbert
The objective of the study is to convince educational researchers of the necessity for "standard mastery curves" for the graphical representation of scores on summative tests for a group of students. Attention is drawn to the study of theoretical and empirical skew curves in education and biology. Use of standard mastery curves and study of skew…
Cho, Sunggoo
2016-09-01
Conics and Cartesian ovals are extremely important curves in various fields of science. In addition, aspheric curves based on conics are useful in optical design. Superconic curves, recently suggested by Greynolds, are extensions of both conics and Cartesian ovals and have been applied to optical design. However, they are not extensions of aspheric curves based on conics. In this work, we investigate another type of superconic curves. These superconic curves are extensions of not only conics and Cartesian ovals but also aspheric curves based on conics. Moreover, these are represented in explicit form, while Greynolds's superconic curves are in implicit form. PMID:27607506
Dossi, Carlo; Monticelli, Damiano; Pozzi, Andrea; Recchia, Sandro; Vezzoli, Luigina
2002-04-01
High-altitude alpine valleys may be considered as ideal field laboratories for the interdisciplinary teaching of Environmental Sciences to undergraduate students in a Laurea degree, since different typologies of sampling sites (rivers, lakes, glaciers) may be found within walking distance, and students are encouraged to develop cooperative learning activities. Scientific data have been collected by 1st year students at the University of Insubria in Como during a teaching program in Ventina Valley and Caronno Valley near Sondrio (Italy). Analytical and geochemical results will be presented and discussed on the basis of organic deposition and water-rock interactions. PMID:12073886
ERIC Educational Resources Information Center
Nordmark, Arne; Essen, Hanno
2007-01-01
The equilibrium of a flexible inextensible string, or chain, in the centrifugal force field of a rotating reference frame is investigated. It is assumed that the end points are fixed on the rotation axis. The shape of the curve, the skipping rope curve or "troposkien", is given by the Jacobi elliptic function sn. (Contains 3 figures.)
Anodic Polarization Curves Revisited
ERIC Educational Resources Information Center
Liu, Yue; Drew, Michael G. B.; Liu, Ying; Liu, Lin
2013-01-01
An experiment published in this "Journal" has been revisited and it is found that the curve pattern of the anodic polarization curve for iron repeats itself successively when the potential scan is repeated. It is surprising that this observation has not been reported previously in the literature because it immediately brings into…
Searcy, James Kincheon
1959-01-01
The flow-duration curve is a cumulative frequency curve that shows the percent of time specified discharges were equaled or exceeded during a given period. It combines in one curve the flow characteristics of a stream throughout the range of discharge, without regard to the sequence of occurrence. If the period upon which the curve is based represents the long-term flow of a stream, the curve may be used to predict the distribution of future flows for water- power, water-supply, and pollution studies. This report shows that differences in geology affect the low-flow ends of flow-duration curves of streams in adjacent basins. Thus, duration curves are useful in appraising the geologic characteristics of drainage basins. A method for adjusting flow-duration curves of short periods to represent long-term conditions is presented. The adjustment is made by correlating the records of a short-term station with those of a long-term station.
NASA Astrophysics Data System (ADS)
Dias, Marcelo A.; Santangelo, Christian D.
2011-03-01
Despite an almost two thousand year history, origami, the art of folding paper, remains a challenge both artistically and scientifically. Traditionally, origami is practiced by folding along straight creases. A whole new set of shapes can be explored, however, if, instead of straight creases, one folds along arbitrary curves. We present a mechanical model for curved fold origami in which the energy of a plastically-deformed crease is balanced by the bending energy of developable regions on either side of the crease. Though geometry requires that a sheet buckle when folded along a closed curve, its shape depends on the elasticity of the sheet. NSF DMR-0846582.
ERIC Educational Resources Information Center
Muscat, Jean-Paul
1992-01-01
Uses LOGO to enhance the applicability of curve stitching in the mathematics curriculum. Presents the formulas and computer programs for the construction of parabolas, concentric circles, and epicycloids. Diagrams of constructed figures are provided. (MDH)
Highly curved microchannel plates
NASA Technical Reports Server (NTRS)
Siegmund, O. H. W.; Cully, S.; Warren, J.; Gaines, G. A.; Priedhorsky, W.; Bloch, J.
1990-01-01
Several spherically curved microchannel plate (MCP) stack configurations were studied as part of an ongoing astrophysical detector development program, and as part of the development of the ALEXIS satellite payload. MCP pairs with surface radii of curvature as small as 7 cm, and diameters up to 46 mm have been evaluated. The experiments show that the gain (greater than 1.5 x 10 exp 7) and background characteristics (about 0.5 events/sq cm per sec) of highly curved MCP stacks are in general equivalent to the performance achieved with flat MCP stacks of similar configuration. However, gain variations across the curved MCP's due to variations in the channel length to diameter ratio are observed. The overall pulse height distribution of a highly curved surface MCP stack (greater than 50 percent FWHM) is thus broader than its flat counterpart (less than 30 percent). Preconditioning of curved MCP stacks gives comparable results to flat MCP stacks, but it also decreases the overall gain variations. Flat fields of curved MCP stacks have the same general characteristics as flat MCP stacks.
Curve Numbers for Golf Course Watersheds
Technology Transfer Automated Retrieval System (TEKTRAN)
Storm event runoff is a critical component to the environmental and structural design related to hydrology. The curve number (CN) method is a robust and accepted method for determining excess rainfall. Measured CNs for golf course watersheds and for that matter hydrologic data from golf course wate...
IGMtransmission: Transmission curve computation
NASA Astrophysics Data System (ADS)
Harrison, Christopher M.; Meiksin, Avery; Stock, David
2015-04-01
IGMtransmission is a Java graphical user interface that implements Monte Carlo simulations to compute the corrections to colors of high-redshift galaxies due to intergalactic attenuation based on current models of the Intergalactic Medium. The effects of absorption due to neutral hydrogen are considered, with particular attention to the stochastic effects of Lyman Limit Systems. Attenuation curves are produced, as well as colors for a wide range of filter responses and model galaxy spectra. Photometric filters are included for the Hubble Space Telescope, the Keck telescope, the Mt. Palomar 200-inch, the SUBARU telescope and UKIRT; alternative filter response curves and spectra may be readily uploaded.
ERIC Educational Resources Information Center
Lawes, Jonathan F.
2013-01-01
Graphing polar curves typically involves a combination of three traditional techniques, all of which can be time-consuming and tedious. However, an alternative method--graphing the polar function on a rectangular plane--simplifies graphing, increases student understanding of the polar coordinate system, and reinforces graphing techniques learned…
ERIC Educational Resources Information Center
Paulton, Richard J. L.
1991-01-01
A procedure that allows students to view an entire bacterial growth curve during a two- to three-hour student laboratory period is described. Observations of the lag phase, logarithmic phase, maximum stationary phase, and phase of decline are possible. A nonpathogenic, marine bacterium is used in the investigation. (KR)
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)
Factorization with genus 2 curves
NASA Astrophysics Data System (ADS)
Cosset, Romain
2010-04-01
The elliptic curve method (ECM) is one of the best factorization methods available. It is possible to use hyperelliptic curves instead of elliptic curves but it is in theory slower. We use special hyperelliptic curves and Kummer surfaces to reduce the complexity of the algorithm. Our implementation GMP-HECM is faster than GMP-ECM for factoring large numbers.
Multivariate curve-fitting in GAUSS
Bunck, C.M.; Pendleton, G.W.
1988-01-01
Multivariate curve-fitting techniques for repeated measures have been developed and an interactive program has been written in GAUSS. The program implements not only the one-factor design described in Morrison (1967) but also includes pairwise comparisons of curves and rates, a two-factor design, and other options. Strategies for selecting the appropriate degree for the polynomial are provided. The methods and program are illustrated with data from studies of the effects of environmental contaminants on ducklings, nesting kestrels and quail.
Boyer, H.E.
1986-01-01
This Atlas was developed to serve engineers who are looking for fatigue data on a particular metal or alloy. Having these curves compiled in a single book will also facilitate the computerization of the involved data. It is pointed out that plans are under way to make the data in this book available in ASCII files for analysis by computer programs. S-N curves which typify effects of major variables are considered along with low-carbon steels, medium-carbon steels, alloy steels, HSLA steels, high-strength alloy steels, heat-resisting steels, stainless steels, maraging steels, cast irons, and heat-resisting alloys. Attention is also given to aluminum alloys, copper alloys, magnesium alloys, molybdenum, tin alloys, titanium and titanium alloys, zirconium, steel castings, closed-die forgings, powder metallurgy parts, composites, effects of surface treatments, and test results for component parts.
Schulz, Douglas A.
2007-10-08
A biometric system suitable for validating user identity using only mouse movements and no specialized equipment is presented. Mouse curves (mouse movements with little or no pause between them) are individually classied and used to develop classication histograms, which are representative of an individual's typical mouse use. These classication histograms can then be compared to validate identity. This classication approach is suitable for providing continuous identity validation during an entire user session.
Anderson, Susan M
2007-01-01
Scoliosis, an abnormal side-to-side curve of the spine with associated vertebral rotation, affects as many as 4% of all adolescents. Several different categories of scoliosis exist, and treatment can range from observation and follow-up to bracing and surgical correction. This article discusses special imaging series for scoliosis and emphasizes the need for proper radiation protection techniques for patients with scoliosis, most of whom are girls in their early to mid-teens. PMID:17848532
Bowen, William H
2013-01-01
The Stephan Curve has played a dominant role in caries research over the past several decades. What is so remarkable about the Stephan Curve is the plethora of interactions it illustrates and yet acid production remains the dominant focus. Using sophisticated technology, it is possible to measure pH changes in plaque; however, these observations may carry a false sense of accuracy. Recent observations have shown that there may be multiple pH values within the plaque matrix, thus emphasizing the importance of the milieu within which acid is formed. Although acid production is indeed the immediate proximate cause of tooth dissolution, the influence of alkali production within plaque has received relative scant attention. Excessive reliance on Stephan Curve leads to describing foods as "safe" if they do not lower the pH below the so-called "critical pH" at which point it is postulated enamel dissolves. Acid production is just one of many biological processes that occur within plaque when exposed to sugar. Exploration of methods to enhance alkali production could produce rich research dividends. PMID:23224410
Debt, Democratization, and Development in Latin America: How Policy Can Affect Global Warming
ERIC Educational Resources Information Center
Aubourg, Rene W.; Good, David H.; Krutilla, Kerry
2008-01-01
The environmental Kuznets curve (EKC) hypothesis conjectures a nonlinear relationship between pollution and economic growth, such that pollution per capita initially increases as countries economically develop, but then reaches a maximum point before ultimately declining. Much of the EKC literature has focused on testing this basic hypothesis and,…
NASA Astrophysics Data System (ADS)
Şenyurt, Süleyman; Altun, Yasin; Cevahir, Ceyda
2016-04-01
In this paper, we investigate the Smarandache curves according to Sabban frame of fixed pole curve which drawn by the unit Darboux vector of the Bertrand partner curve. Some results have been obtained. These results were expressed as the depends Bertrand curve.
The Characteristic Curves of Water
NASA Astrophysics Data System (ADS)
Neumaier, Arnold; Deiters, Ulrich K.
2016-09-01
In 1960, E. H. Brown defined a set of characteristic curves (also known as ideal curves) of pure fluids, along which some thermodynamic properties match those of an ideal gas. These curves are used for testing the extrapolation behaviour of equations of state. This work is revisited, and an elegant representation of the first-order characteristic curves as level curves of a master function is proposed. It is shown that Brown's postulate—that these curves are unique and dome-shaped in a double-logarithmic p, T representation—may fail for fluids exhibiting a density anomaly. A careful study of the Amagat curve (Joule inversion curve) generated from the IAPWS-95 reference equation of state for water reveals the existence of an additional branch.
Titration Curves: Fact and Fiction.
ERIC Educational Resources Information Center
Chamberlain, John
1997-01-01
Discusses ways in which datalogging equipment can enable titration curves to be measured accurately and how computing power can be used to predict the shape of curves. Highlights include sources of error, use of spreadsheets to generate titration curves, titration of a weak acid with a strong alkali, dibasic acids, weak acid and weak base, and…
Birational maps that send biquadratic curves to biquadratic curves
NASA Astrophysics Data System (ADS)
Roberts, John A. G.; Jogia, Danesh
2015-02-01
Recently, many papers have begun to consider so-called non-Quispel-Roberts-Thompson (QRT) birational maps of the plane. Compared to the QRT family of maps which preserve each biquadratic curve in a fibration of the plane, non-QRT maps send a biquadratic curve to another biquadratic curve belonging to the same fibration or to a biquadratic curve from a different fibration of the plane. In this communication, we give the general form of a birational map derived from a difference equation that sends a biquadratic curve to another. The necessary and sufficient condition for such a map to exist is that the discriminants of the two biquadratic curves are the same (and hence so are the j-invariants). The result allows existing examples in the literature to be better understood and allows some statements to be made concerning their generality.
Classification and properties of UV extinction curves
NASA Astrophysics Data System (ADS)
Barbaro, G.; Mazzei, P.; Morbidelli, L.; Patriarchi, P.; Perinotto, M.
2001-01-01
The catalog of Savage et al. (\\cite{ref27}) reporting colour excesses of 1415 stars from ANS photometry offers the opportunity to deeply investigate the characteristics of UV extinction curves which differ from the standard extinction of the diffuse interstellar medium. To this aim we have selected a sample of 252 curves, which have been compared with the relations derived by Cardelli et al. (\\cite{ref4}; CCM in the following) for a variety of R_V values in the range 2.4-5 and have been classified as normal if they fit at least one of the CCM curves or anomalous otherwise. We find that normal curves with small R_V are just as numerous as those with large R_V. The anomalous objects are arranged into two groups according to the strength of the bump at 0.217 mu . For a given value of c_2 this increases along the sequence: type A anomalous, normals and type B anomalous, suggesting that this sequence should correspond to an increase of the amount of small grains along the sightline. Considerations concerning the environmental characteristics indicate that the anomalous behaviour is not necessarily tied to the existence of dense gas clouds along the line of sight.
Synthetic RR Lyrae velocity curves
Liu, Tianxing Boston Univ., MA )
1991-02-01
An amplitude correlation between the pulsation velocity curves and visual light curves of ab-type RR Lyrae stars is derived from a large number of RR Lyrae that have high-precision radial-velocity and photometric data. Based on the determined AVp, AV ralation, a synthetic radial-velocity curve for a typical ab-type RR Lyrae star is constructed. This would be of particular use in determining the systemic velocities of RR Lyrae. 17 refs.
Digital-voltage curve generator
NASA Technical Reports Server (NTRS)
Perlman, M.
1970-01-01
Curve generator capable of producing precisely repeatable curve for any single-valued function of voltage versus time uses digital approach, implemented by means of clocked feedback shift register, large scale integrated circuit diode matrix comprising about 12,000 diodes, counter, and digital-to-analog converter.
NASA Technical Reports Server (NTRS)
Allard, Robert; Calve, Andrew; Pastreck, Edwin; Padden, Edward
1992-01-01
Tool for use in electrical-discharge machining (EDM) guides EDM electrode in making curved holes. Guide rod fits in slot in arm, which moves through arc. Motion drives electrode into workpiece along desired curved path. Electrode burns into workpiece while arm rotates on spindle. Discharge cuts hole of same radius of curvature.
Poiseuille flow in curved spaces
NASA Astrophysics Data System (ADS)
Debus, J.-D.; Mendoza, M.; Succi, S.; Herrmann, H. J.
2016-04-01
We investigate Poiseuille channel flow through intrinsically curved media, equipped with localized metric perturbations. To this end, we study the flux of a fluid driven through the curved channel in dependence of the spatial deformation, characterized by the parameters of the metric perturbations (amplitude, range, and density). We find that the flux depends only on a specific combination of parameters, which we identify as the average metric perturbation, and derive a universal flux law for the Poiseuille flow. For the purpose of this study, we have improved and validated our recently developed lattice Boltzmann model in curved space by considerably reducing discrete lattice effects.
Poiseuille flow in curved spaces.
Debus, J-D; Mendoza, M; Succi, S; Herrmann, H J
2016-04-01
We investigate Poiseuille channel flow through intrinsically curved media, equipped with localized metric perturbations. To this end, we study the flux of a fluid driven through the curved channel in dependence of the spatial deformation, characterized by the parameters of the metric perturbations (amplitude, range, and density). We find that the flux depends only on a specific combination of parameters, which we identify as the average metric perturbation, and derive a universal flux law for the Poiseuille flow. For the purpose of this study, we have improved and validated our recently developed lattice Boltzmann model in curved space by considerably reducing discrete lattice effects. PMID:27176437
Curved characteristics behind blast waves.
NASA Technical Reports Server (NTRS)
Laporte, O.; Chang, T. S.
1972-01-01
The behavior of nonisentropic flow behind a propagating blast wave is theoretically studied. Exact solutions, expressed in closed form in terms of elementary functions, are presented for three sets of curved characteristicseind a self-similar, strong blast wave.
Parabolic curves in Lie groups
Pauley, Michael
2010-05-15
To interpolate a sequence of points in Euclidean space, parabolic splines can be used. These are curves which are piecewise quadratic. To interpolate between points in a (semi-)Riemannian manifold, we could look for curves such that the second covariant derivative of the velocity is zero. We call such curves Jupp and Kent quadratics or JK-quadratics because they are a special case of the cubic curves advocated by Jupp and Kent. When the manifold is a Lie group with bi-invariant metric, we can relate JK-quadratics to null Lie quadratics which arise from another interpolation problem. We solve JK-quadratics in the Lie groups SO(3) and SO(1,2) and in the sphere and hyperbolic plane, by relating them to the differential equation for a quantum harmonic oscillator00.
Flow over riblet curved surfaces
NASA Astrophysics Data System (ADS)
Loureiro, J. B. R.; Silva Freire, A. P.
2011-12-01
The present work studies the mechanics of turbulent drag reduction over curved surfaces by riblets. The effects of surface modification on flow separation over steep and smooth curved surfaces are investigated. Four types of two-dimensional surfaces are studied based on the morphometric parameters that describe the body of a blue whale. Local measurements of mean velocity and turbulence profiles are obtained through laser Doppler anemometry (LDA) and particle image velocimetry (PIV).
Cochlear microphonic broad tuning curves
NASA Astrophysics Data System (ADS)
Ayat, Mohammad; Teal, Paul D.; Searchfield, Grant D.; Razali, Najwani
2015-12-01
It is known that the cochlear microphonic voltage exhibits much broader tuning than does the basilar membrane motion. The most commonly used explanation for this is that when an electrode is inserted at a particular point inside the scala media, the microphonic potentials of neighbouring hair cells have different phases, leading to cancelation at the electrodes location. In situ recording of functioning outer hair cells (OHCs) for investigating this hypothesis is exceptionally difficult. Therefore, to investigate the discrepancy between the tuning curves of the basilar membrane and those of the cochlear microphonic, and the effect of phase cancellation of adjacent hair cells on the broadness of the cochlear microphonic tuning curves, we use an electromechanical model of the cochlea to devise an experiment. We explore the effect of adjacent hair cells (i.e., longitudinal phase cancellation) on the broadness of the cochlear microphonic tuning curves in different locations. The results of the experiment indicate that active longitudinal coupling (i.e., coupling with active adjacent outer hair cells) only slightly changes the broadness of the CM tuning curves. The results also demonstrate that there is a π phase difference between the potentials produced by the hair bundle and the soma near the place associated with the characteristic frequency based on place-frequency maps (i.e., the best place). We suggest that the transversal phase cancellation (caused by the phase difference between the hair bundle and the soma) plays a far more important role than longitudinal phase cancellation in the broadness of the cochlear microphonic tuning curves. Moreover, by increasing the modelled longitudinal resistance resulting the cochlear microphonic curves exhibiting sharper tuning. The results of the simulations suggest that the passive network of the organ of Corti determines the phase difference between the hair bundle and soma, and hence determines the sharpness of the
Relative Locality in Curved Spacetime
NASA Astrophysics Data System (ADS)
Kowalski-Glikman, Jerzy; Rosati, Giacomo
2013-07-01
In this paper we construct the action describing dynamics of the particle moving in curved spacetime, with a nontrivial momentum space geometry. Curved momentum space is the core feature of theories where relative locality effects are present. So far aspects of nonlinearities in momentum space have been studied only for flat or constantly expanding (de Sitter) spacetimes, relying on their maximally symmetric nature. The extension of curved momentum space frameworks to arbitrary spacetime geometries could be relevant for the opportunities to test Planck-scale curvature/deformation of particles momentum space. As a first example of this construction we describe the particle with κ-Poincaré momentum space on a circular orbit in Schwarzschild spacetime, where the contributes of momentum space curvature turn out to be negligible. The analysis of this problem relies crucially on the solution of the soccer ball problem.
Phase nucleation in curved space
NASA Astrophysics Data System (ADS)
Gómez, Leopoldo; García, Nicolás; Vitelli, Vincenzo; Lorenzana, José; Daniel, Vega
Nucleation and growth is the dominant relaxation mechanism driving first-order phase transitions. In two-dimensional flat systems, nucleation has been applied to a wide range of problems in physics, chemistry and biology. Here we study nucleation and growth of two-dimensional phases lying on curved surfaces and show that curvature modifies both critical sizes of nuclei and paths towards the equilibrium phase. In curved space, nucleation and growth becomes inherently inhomogeneous and critical nuclei form faster on regions of positive Gaussian curvature. Substrates of varying shape display complex energy landscapes with several geometry-induced local minima, where initially propagating nuclei become stabilized and trapped by the underlying curvature (Gómez, L. R. et al. Phase nucleation in curved space. Nat. Commun. 6:6856 doi: 10.1038/ncomms7856 (2015).).
Active particles on curved surfaces
NASA Astrophysics Data System (ADS)
Fily, Yaouen; Baskaran, Aparna; Hagan, Michael
Active systems have proved to be very sensitive to the geometry of their environment. This is often achieved by spending significant time at the boundary, probing its shape by gliding along it. I will discuss coarse graining the microscopic dynamics of self-propelled particles on a general curved surface to predict the way the density profile on the surface depends on its geometry. Beyond confined active particles, this formalism is a natural starting point to study objects that cannot leave the boundary at all, such as cells crawling on a curved substrate, animals running on uneven ground, or active colloids trapped at an interface.
Langbein, W.B.
1955-01-01
A common problem in hydrology is to fit a smooth curve to cyclic or periodic data, either to define the most probable values of the data or to test some principle that one wishes to demonstrate. This study treats of those problems where the length or period of the cycle is know beforehand - as a day, year, or meander length for example. Curve-fitting can be made by free-hand drawing, and where the data are closely aligned this method offers the simplest and most direct course. However, there are many problems where the best fit is far from obvious, and analytical methods may be necessary.
NEXT Performance Curve Analysis and Validation
NASA Technical Reports Server (NTRS)
Saripalli, Pratik; Cardiff, Eric; Englander, Jacob
2016-01-01
Performance curves of the NEXT thruster are highly important in determining the thruster's ability in performing towards mission-specific goals. New performance curves are proposed and examined here. The Evolutionary Mission Trajectory Generator (EMTG) is used to verify variations in mission solutions based on both available thruster curves and the new curves generated. Furthermore, variations in BOL and EOL curves are also examined. Mission design results shown here validate the use of EMTG and the new performance curves.
Supply Curves of Conserved Energy
Meier, Alan Kevin
1982-05-01
Supply curves of conserved energy provide an accounting framework that expresses the potential for energy conservation. The economic worthiness of a conservation measure is expressed in terms of the cost of conserved energy, and a measure is considered economical when the cost of conserved energy is less than the price of the energy it replaces. A supply curve of conserved energy is independent of energy prices; however, the economical reserves of conserved energy will depend on energy prices. Double-counting of energy savings and error propagation are common problems when estimating conservation potentials, but supply curves minimize these difficulties and make their consequences predictable. The sensitivity of the cost of conserved energy is examined, as are variations in the optimal investment strategy in response to changes in inputs. Guidelines are presented for predicting the consequences of such changes. The conservation supply curve concept can be applied to peak power, water, pollution, and other markets where consumers demand a service rather than a particular good.
Interpolation and Polynomial Curve Fitting
ERIC Educational Resources Information Center
Yang, Yajun; Gordon, Sheldon P.
2014-01-01
Two points determine a line. Three noncollinear points determine a quadratic function. Four points that do not lie on a lower-degree polynomial curve determine a cubic function. In general, n + 1 points uniquely determine a polynomial of degree n, presuming that they do not fall onto a polynomial of lower degree. The process of finding such a…
Geomorphological origin of recession curves
NASA Astrophysics Data System (ADS)
Biswal, Basudev; Marani, Marco
2010-12-01
We identify a previously undetected link between the river network morphology and key recession curves properties through a conceptual-physical model of the drainage process of the riparian unconfined aquifer. We show that the power-law exponent, α, of -dQ/dt vs. Q curves is related to the power-law exponent of N(l) vs. G(l) curves (which we show to be connected to Hack's law), where l is the downstream distance from the channel heads, N(l) is the number of channel reaches exactly located at a distance l from their channel head, and G(l) is the total length of the network located at a distance greater or equal to l from channel heads. Using Digital Terrain Models and daily discharge observations from 67 US basins we find that geomorphologic α estimates match well the values obtained from recession curves analyses. Finally, we argue that the link between recession flows and network morphology points to an important role of low-flow discharges in shaping the channel network.
CURVES, VERTICES, KNOTS AND SUCH.
ERIC Educational Resources Information Center
FOLEY, JACK L.
THIS BOOKLET, ONE OF A SERIES, HAS BEEN DEVELOPED FOR THE PROJECT, A PROGRAM FOR MATHEMATICALLY UNDERDEVELOPED PUPILS. A PROJECT TEAM, INCLUDING INSERVICE TEACHERS, IS BEING USED TO WRITE AND DEVELOP THE MATERIALS FOR THIS PROGRAM. THE MATERIALS DEVELOPED IN THIS BOOKLET INCLUDE SUCH CONCEPTS AS (1) SIMPLE CLOSED CURVES, (2) NETWORKS, (3) MAP…
Comparison of Two Algebraic Methods for Curve/curve Intersection
NASA Technical Reports Server (NTRS)
Demontaudouin, Y.; Tiller, W.
1985-01-01
Most geometric modeling systems use either polynomial or rational functions to represent geometry. In such systems most computational problems can be formulated as systems of polynomials in one or more variables. Classical elimination theory can be used to solve such systems. Here Cayley's method of elimination is summarized and it is shown how it can best be used to solve the curve/curve intersection problem. Cayley's method was found to be a more straightforward approach. Furthermore, it is computationally simpler, since the elements of the Cayley matrix are one variable instead of two variable polynomials. Researchers implemented and tested both methods and found Cayley's to be more efficient. Six pairs of curves, representing mixtures of lines, circles, and cubic arcs were used. Several examples had multiple intersection points. For all six cases Cayley's required less CPU time than the other method. The average time ratio of method 1 to method 2 was 3.13:1, the least difference was 2.33:1, and the most dramatic was 6.25:1. Both of the above methods can be extended to solve the surface/surface intersection problem.
Optical conductivity of curved graphene.
Chaves, A J; Frederico, T; Oliveira, O; de Paula, W; Santos, M C
2014-05-01
We compute the optical conductivity for an out-of-plane deformation in graphene using an approach based on solutions of the Dirac equation in curved space. Different examples of periodic deformations along one direction translates into an enhancement of the optical conductivity peaks in the region of the far- and mid-infrared frequencies for periodicities ∼100 nm. The width and position of the peaks can be changed by dialling the parameters of the deformation profiles. The enhancement of the optical conductivity is due to intraband transitions and the translational invariance breaking in the geometrically deformed background. Furthermore, we derive an analytical solution of the Dirac equation in a curved space for a general deformation along one spatial direction. For this class of geometries, it is shown that curvature induces an extra phase in the electron wave function, which can also be explored to produce interference devices of the Aharonov-Bohm type. PMID:24759188
Flow Through Randomly Curved Manifolds
Mendoza, M.; Succi, S.; Herrmann, H. J.
2013-01-01
We present a computational study of the transport properties of campylotic (intrinsically curved) media. It is found that the relation between the flow through a campylotic media, consisting of randomly located curvature perturbations, and the average Ricci scalar of the system, exhibits two distinct functional expressions, depending on whether the typical spatial extent of the curvature perturbation lies above or below the critical value maximizing the overall scalar of curvature. Furthermore, the flow through such systems as a function of the number of curvature perturbations is found to present a sublinear behavior for large concentrations, due to the interference between curvature perturbations leading to an overall less curved space. We have also characterized the flux through such media as a function of the local Reynolds number and the scale of interaction between impurities. For the purpose of this study, we have also developed and validated a new lattice Boltzmann model. PMID:24173367
Analysis of Exoplanet Light Curves
NASA Astrophysics Data System (ADS)
Erdem, A.; Budding, E.; Rhodes, M. D.; Püsküllü, Ç.; Soydugan, F.; Soydugan, E.; Tüysüz, M.; Demircan, O.
2015-07-01
We have applied the close binary system analysis package WINFITTER to a variety of exoplanet transiting light curves taken both from the NASA Exoplanet Archive and our own ground-based observations. WINFitter has parameter options for a realistic physical model, including gravity brightening and structural parameters derived from Kopal's applications of the relevant Radau equation, and it includes appropriate tests for determinacy and adequacy of its best fitting parameter sets. We discuss a number of issues related to empirical checking of models for stellar limb darkening, surface maculation, Doppler beaming, microvariability, and transit time variation (TTV) effects. The Radau coefficients used in the light curve modeling, in principle, allow structural models of the component stars to be tested.
Quantum walking in curved spacetime
NASA Astrophysics Data System (ADS)
Arrighi, Pablo; Facchini, Stefano; Forets, Marcelo
2016-08-01
A discrete-time quantum walk (QW) is essentially a unitary operator driving the evolution of a single particle on the lattice. Some QWs admit a continuum limit, leading to familiar PDEs (e.g., the Dirac equation). In this paper, we study the continuum limit of a wide class of QWs and show that it leads to an entire class of PDEs, encompassing the Hamiltonian form of the massive Dirac equation in (1+1) curved spacetime. Therefore, a certain QW, which we make explicit, provides us with a unitary discrete toy model of a test particle in curved spacetime, in spite of the fixed background lattice. Mathematically, we have introduced two novel ingredients for taking the continuum limit of a QW, but which apply to any quantum cellular automata: encoding and grouping.
Gravitational-wave sensitivity curves
NASA Astrophysics Data System (ADS)
Moore, C. J.; Cole, R. H.; Berry, C. P. L.
2015-01-01
There are several common conventions in use by the gravitational-wave community to describe the amplitude of sources and the sensitivity of detectors. These are frequently confused. We outline the merits of and differences between the various quantities used for parameterizing noise curves and characterizing gravitational-wave amplitudes. We conclude by producing plots that consistently compare different detectors. Similar figures can be generated on-line for general use at http://rhcole.com/apps/GWplotter.
NASA Astrophysics Data System (ADS)
Armstrong McKay, David I.; Dearing, John A.; Dyke, James G.; Poppy, Guy; Firbank, Les
2016-04-01
yield. Soil erosion / suspended sediment transport and atmospheric pollution have also declined, but some biodiversity degradation metrics continue to rise. Environmental degradation resulting from agriculture in this region appears to have followed the trajectory of an Environmental Kuznets Curve, with recent years showing that regional GDP growth has begun to decouple from ecological deterioration. The history of South-West England is complicated by the significant drop in livestock density as a result of the 2001 foot-and-mouth disease outbreak and highly variable erosion data, but in general a similar pattern of increasing degradation in the 1980s and a gradual recovery since ~2000 is observed. Data with higher spatial and temporal resolution is required in order to further investigate the differing behaviour of the agri-environment system in each region. Based on this analysis, the preliminary results of a prototype dynamical systems model of regional agri-environment systems in the UK is also presented. Further development of this model will enhance our ability to identify regional social-ecological system boundaries and to detect the potential presence of tipping points within them.
Phase Curves of Eccentric Exoplanets
NASA Astrophysics Data System (ADS)
Lewis, Nikole K.; de Wit, Julien; Laughlin, Gregory P.; Knutson, Heather
2016-01-01
Nearly 15% of the known exoplanet population have significantly eccentric orbits (e > 0.25). Systems with planets on highly eccentric orbits provide natural laboratories to test theories of orbital evolution, tidal forcing, and atmospheric response. The two best studied eccentric exoplanets are HAT-P-2b (e~0.5) and HD 80606 b (e~0.9). Both of these eccentric planets have full or partial orbit phase curve observations taken with the 3.6, 4.5, and 8.0 micron channels of the Spitzer IRAC instrument. These phase-curve observations of HAT-P-2b and HD 80606 b have given us important insights into atmospheric radiative timescales, planetary rotation rates and orbital evolution, and planet-star tidal interactions. Here I will overview the key results from the Spitzer observational campaigns for HAT-P-2b and HD 80606 b and look toward the future of phase curve observations of eccentric exoplanets in the era of JWST.
Growth curves for Laron syndrome.
Laron, Z; Lilos, P; Klinger, B
1993-01-01
Growth curves for children with Laron syndrome were constructed on the basis of repeated measurements made throughout infancy, childhood, and puberty in 24 (10 boys, 14 girls) of the 41 patients with this syndrome investigated in our clinic. Growth retardation was already noted at birth, the birth length ranging from 42 to 46 cm in the 12/20 available measurements. The postnatal growth curves deviated sharply from the normal from infancy on. Both sexes showed no clear pubertal spurt. Girls completed their growth between the age of 16-19 years to a final mean (SD) height of 119 (8.5) cm whereas the boys continued growing beyond the age of 20 years, achieving a final height of 124 (8.5) cm. At all ages the upper to lower body segment ratio was more than 2 SD above the normal mean. These growth curves constitute a model not only for primary, hereditary insulin-like growth factor-I (IGF-I) deficiency (Laron syndrome) but also for untreated secondary IGF-I deficiencies such as growth hormone gene deletion and idiopathic congenital isolated growth hormone deficiency. They should also be useful in the follow up of children with Laron syndrome treated with biosynthetic recombinant IGF-I. PMID:8333769
Compression of contour data through exploiting curve-to-curve dependence
NASA Technical Reports Server (NTRS)
Yalabik, N.; Cooper, D. B.
1975-01-01
An approach to exploiting curve-to-curve dependencies in order to achieve high data compression is presented. One of the approaches to date of along curve compression through use of cubic spline approximation is taken and extended by investigating the additional compressibility achievable through curve-to-curve structure exploitation. One of the models under investigation is reported on.
Fracture toughness curve shift method
Nanstad, R.K.; Sokolov, M.A.; McCabe, D.E.
1995-10-01
The purpose of this task is to examine the technical basis for the currently accepted methods for shifting fracture toughness curves to account for irradiation damage, and to work through national codes and standards bodies to revise those methods, if a change is warranted. During this reporting period, data from all the relevant HSSI Programs were acquired and stored in a database and evaluated. The results from that evaluation have been prepared in a draft letter report and are summarized here. A method employing Weibull statistics was applied to analyze fracture toughness properties of unirradiated and irradiated pressure vessel steels. Application of the concept of a master curve for irradiated materials was examined and used to measure shifts of fracture toughness transition curves. It was shown that the maximum likelihood approach gave good estimations of the reference temperature, T{sub o}, determined by rank method and could be used for analyzing of data sets where application of the rank method did not prove to be feasible. It was shown that, on average, the fracture toughness shifts generally exceeded the Charpy 41-J shifts; a linear least-squares fit to the data set yielded a slope of 1.15. The observed dissimilarity was analyzed by taking into account differences in effects of irradiation on Charpy impact and fracture toughness properties. Based on these comparisons, a procedure to adjust Charpy 41-J shifts for achieving a more reliable correlation with the fracture toughness shifts was evaluated. An adjustment consists of multiplying the 41-J energy level by the ratio of unirradiated to irradiated Charpy upper shelves to determine an irradiated transition temperature, and then subtracting the unirradiated transition temperature determined at 41 J. For LUS welds, however, an unirradiated level of 20 J (15 ft-1b) was used for the corresponding adjustment for irradiated material.
NLINEAR - NONLINEAR CURVE FITTING PROGRAM
NASA Technical Reports Server (NTRS)
Everhart, J. L.
1994-01-01
A common method for fitting data is a least-squares fit. In the least-squares method, a user-specified fitting function is utilized in such a way as to minimize the sum of the squares of distances between the data points and the fitting curve. The Nonlinear Curve Fitting Program, NLINEAR, is an interactive curve fitting routine based on a description of the quadratic expansion of the chi-squared statistic. NLINEAR utilizes a nonlinear optimization algorithm that calculates the best statistically weighted values of the parameters of the fitting function and the chi-square that is to be minimized. The inputs to the program are the mathematical form of the fitting function and the initial values of the parameters to be estimated. This approach provides the user with statistical information such as goodness of fit and estimated values of parameters that produce the highest degree of correlation between the experimental data and the mathematical model. In the mathematical formulation of the algorithm, the Taylor expansion of chi-square is first introduced, and justification for retaining only the first term are presented. From the expansion, a set of n simultaneous linear equations are derived, which are solved by matrix algebra. To achieve convergence, the algorithm requires meaningful initial estimates for the parameters of the fitting function. NLINEAR is written in Fortran 77 for execution on a CDC Cyber 750 under NOS 2.3. It has a central memory requirement of 5K 60 bit words. Optionally, graphical output of the fitting function can be plotted. Tektronix PLOT-10 routines are required for graphics. NLINEAR was developed in 1987.
Dirac's aether in curved spacetime.
Oliveira; Teixeira
2000-06-01
Proca's equations for two types of fields in a Dirac's aether with electric conductivity sigma are solved exactly. The Proca electromagnetic fields are assumed with cylindrical symmetry. The background is a static, curved spacetime whose spatial section is homogeneous and has the topology of either the three-sphere S 3 or the projective three-space P 3. Simple relations between the range of Proca field lambda, the Universe radius R, the limit of photon rest mass mgamma and the conductivity sigma are written down. PMID:10932114
Seeing effects on occultation curves.
NASA Technical Reports Server (NTRS)
Young, A. T.
1971-01-01
Evaluation of seeing effects on the light curve of a stellar occultation by the moon. Some theoretical studies of Fried (1966) and Hulett (1967) on the linear size of the downward-looking seeing disk are cited, showing that the seeing blur amounts to a few centimeters for a star in the zenith and that the linear blur must grow approximately as (sec z) to the 3/2 power. For most observations the seeing blur will not exceed 8 to 10 cm. The limitation on angular resolution imposed by this seeing effect is calculated.
Observable Zitterbewegung in curved spacetimes
NASA Astrophysics Data System (ADS)
Kobakhidze, Archil; Manning, Adrian; Tureanu, Anca
2016-06-01
Zitterbewegung, as it was originally described by Schrödinger, is an unphysical, non-observable effect. We verify whether the effect can be observed in non-inertial reference frames/curved spacetimes, where the ambiguity in defining particle states results in a mixing of positive and negative frequency modes. We explicitly demonstrate that such a mixing is in fact necessary to obtain the correct classical value for a particle's velocity in a uniformly accelerated reference frame, whereas in cosmological spacetime a particle does indeed exhibit Zitterbewegung.
Miniature curved artificial compound eyes
Floreano, Dario; Pericet-Camara, Ramon; Viollet, Stéphane; Ruffier, Franck; Brückner, Andreas; Leitel, Robert; Buss, Wolfgang; Menouni, Mohsine; Expert, Fabien; Juston, Raphaël; Dobrzynski, Michal Karol; L’Eplattenier, Geraud; Recktenwald, Fabian; Mallot, Hanspeter A.; Franceschini, Nicolas
2013-01-01
In most animal species, vision is mediated by compound eyes, which offer lower resolution than vertebrate single-lens eyes, but significantly larger fields of view with negligible distortion and spherical aberration, as well as high temporal resolution in a tiny package. Compound eyes are ideally suited for fast panoramic motion perception. Engineering a miniature artificial compound eye is challenging because it requires accurate alignment of photoreceptive and optical components on a curved surface. Here, we describe a unique design method for biomimetic compound eyes featuring a panoramic, undistorted field of view in a very thin package. The design consists of three planar layers of separately produced arrays, namely, a microlens array, a neuromorphic photodetector array, and a flexible printed circuit board that are stacked, cut, and curved to produce a mechanically flexible imager. Following this method, we have prototyped and characterized an artificial compound eye bearing a hemispherical field of view with embedded and programmable low-power signal processing, high temporal resolution, and local adaptation to illumination. The prototyped artificial compound eye possesses several characteristics similar to the eye of the fruit fly Drosophila and other arthropod species. This design method opens up additional vistas for a broad range of applications in which wide field motion detection is at a premium, such as collision-free navigation of terrestrial and aerospace vehicles, and for the experimental testing of insect vision theories. PMID:23690574
Miniature curved artificial compound eyes.
Floreano, Dario; Pericet-Camara, Ramon; Viollet, Stéphane; Ruffier, Franck; Brückner, Andreas; Leitel, Robert; Buss, Wolfgang; Menouni, Mohsine; Expert, Fabien; Juston, Raphaël; Dobrzynski, Michal Karol; L'Eplattenier, Geraud; Recktenwald, Fabian; Mallot, Hanspeter A; Franceschini, Nicolas
2013-06-01
In most animal species, vision is mediated by compound eyes, which offer lower resolution than vertebrate single-lens eyes, but significantly larger fields of view with negligible distortion and spherical aberration, as well as high temporal resolution in a tiny package. Compound eyes are ideally suited for fast panoramic motion perception. Engineering a miniature artificial compound eye is challenging because it requires accurate alignment of photoreceptive and optical components on a curved surface. Here, we describe a unique design method for biomimetic compound eyes featuring a panoramic, undistorted field of view in a very thin package. The design consists of three planar layers of separately produced arrays, namely, a microlens array, a neuromorphic photodetector array, and a flexible printed circuit board that are stacked, cut, and curved to produce a mechanically flexible imager. Following this method, we have prototyped and characterized an artificial compound eye bearing a hemispherical field of view with embedded and programmable low-power signal processing, high temporal resolution, and local adaptation to illumination. The prototyped artificial compound eye possesses several characteristics similar to the eye of the fruit fly Drosophila and other arthropod species. This design method opens up additional vistas for a broad range of applications in which wide field motion detection is at a premium, such as collision-free navigation of terrestrial and aerospace vehicles, and for the experimental testing of insect vision theories. PMID:23690574
Reciprocal relations between kinetic curves
NASA Astrophysics Data System (ADS)
Yablonsky, G. S.; Gorban, A. N.; Constales, D.; Galvita, V. V.; Marin, G. B.
2011-01-01
We study coupled irreversible processes. For linear or linearized kinetics with microreversibility, \\dot{x}=Kx , the kinetic operator K is symmetric in the entropic inner product. This form of Onsager's reciprocal relations implies that the shift in time, exp(Kt), is also a symmetric operator. This generates the reciprocity relations between the kinetic curves. For example, for the Master equation, if we start the process from the i-th pure state and measure the probability pj(t) of the j-th state (j≠i), and, similarly, measure pi(t) for the process, which starts at the j-th pure state, then the ratio of these two probabilities pj(t)/pi(t) is constant in time and coincides with the ratio of the equilibrium probabilities. We study similar and more general reciprocal relations between the kinetic curves. The experimental evidence provided as an example is from the reversible water gas shift reaction over iron oxide catalyst. The experimental data are obtained using Temporal Analysis of Products (TAP) pulse-response studies. These offer excellent confirmation within the experimental error.
Implicit dose-response curves.
Pérez Millán, Mercedes; Dickenstein, Alicia
2015-06-01
We develop tools from computational algebraic geometry for the study of steady state features of autonomous polynomial dynamical systems via elimination of variables. In particular, we obtain nontrivial bounds for the steady state concentration of a given species in biochemical reaction networks with mass-action kinetics. This species is understood as the output of the network and we thus bound the maximal response of the system. The improved bounds give smaller starting boxes to launch numerical methods. We apply our results to the sequential enzymatic network studied in Markevich et al. (J Cell Biol 164(3):353-359, 2004) to find nontrivial upper bounds for the different substrate concentrations at steady state. Our approach does not require any simulation, analytical expression to describe the output in terms of the input, or the absence of multistationarity. Instead, we show how to extract information from effectively computable implicit dose-response curves, with the use of resultants and discriminants. We moreover illustrate in the application to an enzymatic network, the relation between the exact implicit dose-response curve we obtain symbolically and the standard hysteresis diagram provided by a numerical ode solver. The setting and tools we propose could yield many other results adapted to any autonomous polynomial dynamical system, beyond those where it is possible to get explicit expressions. PMID:25008963
Galois Representations Connected with Hyperbolic Curves
NASA Astrophysics Data System (ADS)
Voevodskiĭ, V. A.
1992-06-01
The author considers Galois group actions on the fundamental groups of curves of hyperbolic type, and proves certain cases of Grothendieck's conjecture about the possibility of recovering a curve from its Galois representation.
Thermoluminescence glow curve analysis and CGCD method for erbium doped CaZrO3 phosphor
NASA Astrophysics Data System (ADS)
Tiwari, Ratnesh; Chopra, Seema
2016-05-01
The manuscript report the synthesis, thermoluminescence study at fixed concentration of Er3+ (1 mol%) doped CaZrO3 phosphor. The phosphors were prepared by modified solid state reaction method. The powder sample was characterized by thermoluminescence (TL) glow curve analysis. In TL glow curve the optimized concentration in 1mol% for UV irradiated sample. The kinetic parameters were calculated by computerized glow curve deconvolution (CGCD) techniaue. Trapping parameters gives the information of dosimetry loss in prepared phosphor and its usability in environmental monitoring and for personal monitoring. CGCD is the advance tool for analysis of complicated TL glow curves.
The general efficiency curve for air propellers
NASA Technical Reports Server (NTRS)
Diehl, Walter S
1924-01-01
This report presents a formula which may be used to obtain a "general efficiency curve" in addition to the well-known maximum efficiency curve. These two curves, when modified somewhat by experimental data, enable performance calculations to be made without detailed knowledge of the propeller. The curves may also be used to estimate the improvement in efficiency due to reduction gearing, or to judge the performance of a new propeller design.
Sustainability and Environmental Economics: Some Critical Foci
I present five seminal concepts of environmental economic thought and discuss their applicability to the idea of sustainability. These five, Maximum Sustainable Yield and Steady-state, The Environmental Kuznet’s curve, Substitutability, Discount rate and Intergenerational equity...
NASA Astrophysics Data System (ADS)
Foray, Vincent; Gibert, Patricia; Desouhant, Emmanuel
2011-08-01
Environmental variability is expected to be important in shaping performance curves, reaction norms of phenotypic traits related to fitness. Models predict that the breadth of performance curves should increase with environmental variability at the expense of maximal performance. In this study, we compared the thermal performance curves of two sympatric populations of the parasitoid Venturia canescens that were observed under contrasting thermal regimes in their respective preferred habitats and differing in their modes of reproduction. Our results confirm the large effect of developmental temperature on phenotypic traits of insects and demonstrate that thelytokous and arrhenotokous wasps respond differently to temperature during development, in agreement with model predictions. For traits related to fecundity, thelytokous parasitoids, which usually occur in stable thermal conditions, exhibit specialist performance curves, maximising their reproductive success under a restricted range of temperature. In contrast, arrhenotokous parasitoids, which occur in variable climates, exhibit generalist performance curves, in keeping with the hypothesis "jack of all temperatures, master of none".
Bacterial streamers in curved microchannels
NASA Astrophysics Data System (ADS)
Rusconi, Roberto; Lecuyer, Sigolene; Guglielmini, Laura; Stone, Howard
2009-11-01
Biofilms, generally identified as microbial communities embedded in a self-produced matrix of extracellular polymeric substances, are involved in a wide variety of health-related problems ranging from implant-associated infections to disease transmissions and dental plaque. The usual picture of these bacterial films is that they grow and develop on surfaces. However, suspended biofilm structures, or streamers, have been found in natural environments (e.g., rivers, acid mines, hydrothermal hot springs) and are always suggested to stem from a turbulent flow. We report the formation of bacterial streamers in curved microfluidic channels. By using confocal laser microscopy we are able to directly image and characterize the spatial and temporal evolution of these filamentous structures. Such streamers, which always connect the inner corners of opposite sides of the channel, are always located in the middle plane. Numerical simulations of the flow provide evidences for an underlying hydrodynamic mechanism behind the formation of the streamers.
Euler characteristics and elliptic curves.
Coates, J; Howson, S
1997-10-14
Let E be a modular elliptic curve over [symbol, see text], without complex multiplication; let p be a prime number where E has good ordinary reduction; and let Finfinity be the field obtained by adjoining [symbol, see text] to all p-power division points on E. Write Ginfinity for the Galois group of Finfinity over [symbol, see text]. Assume that the complex L-series of E over [symbol, see text] does not vanish at s = 1. If p >/= 5, we make a precise conjecture about the value of the Ginfinity-Euler characteristic of the Selmer group of E over Finfinity. If one makes a standard conjecture about the behavior of this Selmer group as a module over the Iwasawa algebra, we are able to prove our conjecture. The crucial local calculations in the proof depend on recent joint work of the first author with R. Greenberg. PMID:11607752
Spinning bodies in curved spacetime
NASA Astrophysics Data System (ADS)
d'Ambrosi, G.; Satish Kumar, S.; van de Vis, J.; van Holten, J. W.
2016-02-01
We study the motion of neutral and charged spinning bodies in curved spacetime in the test-particle limit. We construct equations of motion using a closed covariant Poisson-Dirac bracket formulation that allows for different choices of the Hamiltonian. We derive conditions for the existence of constants of motion and apply the formalism to the case of spherically symmetric spacetimes. We show that the periastron of a spinning body in a stable orbit in a Schwarzschild or Reissner-Nordstrøm background not only precesses but also varies radially. By analyzing the stability conditions for circular motion we find the innermost stable circular orbit (ISCO) as a function of spin. It turns out that there is an absolute lower limit on the ISCOs for increasing prograde spin. Finally we establish that the equations of motion can also be derived from the Einstein equations using an appropriate energy-momentum tensor for spinning particles.
Hexatic undulations in curved geometries.
Lenz, Peter; Nelson, David R
2003-03-01
We discuss the influence of two-dimensional hexatic order on capillary waves and undulation modes in spherical and cylindrical geometries. In planar geometries, extended bond-orientational order has only a minor effect on the fluctuations of liquid surfaces or lipid bilayers. However, in curved geometries, the long-wavelength spectrum of these ripples is altered. We calculate this frequency shift and discuss applications to spherical vesicles, liquid metal droplets, bubbles and cylindrical jets coated with surface-active molecules, and to multielectron bubbles in liquid helium at low temperatures. Hexatic order also leads to a shift in the threshold for the fission instability of charged droplets and bubbles, and for the Plateau-Rayleigh instability of liquid jets. PMID:12689068
Caloric curve of star clusters.
Casetti, Lapo; Nardini, Cesare
2012-06-01
Self-gravitating systems, such as globular clusters or elliptical galaxies, are the prototypes of many-body systems with long-range interactions, and should be the natural arena in which to test theoretical predictions on the statistical behavior of long-range-interacting systems. Systems of classical self-gravitating particles can be studied with the standard tools of equilibrium statistical mechanics, provided the potential is regularized at small length scales and the system is confined in a box. The confinement condition looks rather unphysical in general, so that it is natural to ask whether what we learn with these studies is relevant to real self-gravitating systems. In order to provide an answer to this question, we consider a basic, simple, yet effective model of globular clusters: the King model. This model describes a self-consistently confined system, without the need of any external box, but the stationary state is a nonthermal one. In particular, we consider the King model with a short-distance cutoff on the interactions, and we discuss how such a cutoff affects the caloric curve, i.e., the relation between temperature and energy. We find that the cutoff stabilizes a low-energy phase, which is absent in the King model without cutoff; the caloric curve of the model with cutoff turns out to be very similar to that of previously studied confined and regularized models, but for the absence of a high-energy gaslike phase. We briefly discuss the possible phenomenological as well as theoretical implications of these results. PMID:23005049
AKLSQF - LEAST SQUARES CURVE FITTING
NASA Technical Reports Server (NTRS)
Kantak, A. V.
1994-01-01
The Least Squares Curve Fitting program, AKLSQF, computes the polynomial which will least square fit uniformly spaced data easily and efficiently. The program allows the user to specify the tolerable least squares error in the fitting or allows the user to specify the polynomial degree. In both cases AKLSQF returns the polynomial and the actual least squares fit error incurred in the operation. The data may be supplied to the routine either by direct keyboard entry or via a file. AKLSQF produces the least squares polynomial in two steps. First, the data points are least squares fitted using the orthogonal factorial polynomials. The result is then reduced to a regular polynomial using Sterling numbers of the first kind. If an error tolerance is specified, the program starts with a polynomial of degree 1 and computes the least squares fit error. The degree of the polynomial used for fitting is then increased successively until the error criterion specified by the user is met. At every step the polynomial as well as the least squares fitting error is printed to the screen. In general, the program can produce a curve fitting up to a 100 degree polynomial. All computations in the program are carried out under Double Precision format for real numbers and under long integer format for integers to provide the maximum accuracy possible. AKLSQF was written for an IBM PC X/AT or compatible using Microsoft's Quick Basic compiler. It has been implemented under DOS 3.2.1 using 23K of RAM. AKLSQF was developed in 1989.
Force-extension curves of bacterial flagella.
Vogel, R; Stark, H
2010-11-01
Bacterial flagella assume different helical shapes during the tumbling phase of a bacterium but also in response to varying environmental conditions. Force-extension measurements by Darnton and Berg explicitly demonstrate a transformation from the coiled to the normal helical state (N.C. Darnton, H.C. Berg, Biophys. J. 92, 2230 (2007)). We here develop an elastic model for the flagellum based on Kirchhoff's theory of an elastic rod that describes such a polymorphic transformation and use resistive force theory to couple the flagellum to the aqueous environment. We present Brownian-dynamics simulations that quantitatively reproduce the force-extension curves and study how the ratio Γ of torsional to bending rigidity and the extensional rate influence the response of the flagellum. An upper bound for Γ is given. Using clamped flagella, we show in an adiabatic approximation that the mean extension, where a local coiled-to-normal transition occurs first, depends on the logarithm of the extensional rate. PMID:21046183
Why subduction zones are curved
NASA Astrophysics Data System (ADS)
Mahadevan, L.; Bendick, R.; Liang, Haiyi
2010-12-01
We give an explanation for the polarity, localization, shape, size, and initiation of subduction zones on Earth. By considering a soft, thin, curved lithospheric cap with either elastic or viscous rheology supported by a thick, nearly incompressible mantle, we find two different characteristic subduction geometries arise depending on boundary conditions: (1) plate boundaries where subduction results primarily from the gravitational body force (free subduction) have characteristic plate lengths and form arc-shaped dimpled segments resulting from the competition between bending and stretching in edge buckling modes of thin spherical shells, and (2) subduction zones due to localized applied loads that push one slab of thin, positively buoyant lithosphere beneath an overriding plate (forced subduction) form localized straight segments, consistent with the deformation of indented spherical shells. Both types of subduction are nonlinear subcritical instabilities, so small perturbations in the mechanical properties of the lithosphere have pronounced effects on subduction initiation and evolution. Yet in both cases, geometric relationships determined by the shape of the Earth itself play the most critical role in controlling the basic morphology and characteristic length scales of subduction zones.
Differentialless geometry of plane curves
NASA Astrophysics Data System (ADS)
Latecki, Longin J.; Rosenfeld, Azriel
1997-10-01
We introduce a class of planar arcs and curves, called tame arcs, which is general enough to describe the boundaries of planar real objects. A tame arc can have smooth parts as well as sharp corners; thus a polygonal arc is tame. On the other hand, this class of arcs is restrictive enough to rule out pathological arcs which have infinitely many inflections or which turn infinitely often: a tame arc can have only finitely many inflections, and its total absolute turn must be finite. In order to relate boundary properties of discrete objects obtained by segmenting digital images to the corresponding properties of their continuous originals, the theory of tame arcs is based on concepts that can be directly transferred from the continuous to the discrete domain. A tame arc is composed of a finite number of supported arcs. We define supported digital arcs and motivate their definition by the fact that hey can be obtained by digitizing continuous supported arcs. Every digital arc is tame, since it contains a finite number of points, and therefore it can be decomposed into a finite number of supported digital arcs.
Learning curve of speech recognition.
Kauppinen, Tomi A; Kaipio, Johanna; Koivikko, Mika P
2013-12-01
Speech recognition (SR) speeds patient care processes by reducing report turnaround times. However, concerns have emerged about prolonged training and an added secretarial burden for radiologists. We assessed how much proofing radiologists who have years of experience with SR and radiologists new to SR must perform, and estimated how quickly the new users become as skilled as the experienced users. We studied SR log entries for 0.25 million reports from 154 radiologists and after careful exclusions, defined a group of 11 experienced radiologists and 71 radiologists new to SR (24,833 and 122,093 reports, respectively). Data were analyzed for sound file and report lengths, character-based error rates, and words unknown to the SR's dictionary. Experienced radiologists corrected 6 characters for each report and for new users, 11. Some users presented a very unfavorable learning curve, with error rates not declining as expected. New users' reports were longer, and data for the experienced users indicates that their reports, initially equally lengthy, shortened over a period of several years. For most radiologists, only minor corrections of dictated reports were necessary. While new users adopted SR quickly, with a subset outperforming experienced users from the start, identification of users struggling with SR will help facilitate troubleshooting and support. PMID:23779151
Quantum fields in curved spacetime
NASA Astrophysics Data System (ADS)
Hollands, Stefan; Wald, Robert M.
2015-04-01
We review the theory of quantum fields propagating in an arbitrary, classical, globally hyperbolic spacetime. Our review emphasizes the conceptual issues arising in the formulation of the theory and presents known results in a mathematically precise way. Particular attention is paid to the distributional nature of quantum fields, to their local and covariant character, and to microlocal spectrum conditions satisfied by physically reasonable states. We review the Unruh and Hawking effects for free fields, as well as the behavior of free fields in deSitter spacetime and FLRW spacetimes with an exponential phase of expansion. We review how nonlinear observables of a free field, such as the stress-energy tensor, are defined, as well as time-ordered-products. The "renormalization ambiguities" involved in the definition of time-ordered products are fully characterized. Interacting fields are then perturbatively constructed. Our main focus is on the theory of a scalar field, but a brief discussion of gauge fields is included. We conclude with a brief discussion of a possible approach towards a nonperturbative formulation of quantum field theory in curved spacetime and some remarks on the formulation of quantum gravity.
Stochastic Index estimation of flow duration curves on ephemeral basins
NASA Astrophysics Data System (ADS)
Rianna, Maura; Napolitano, Francesco; Russo, Fabio
2010-05-01
Flow duration curves (FDC) and annual flow duration curves can be used for describe the flow river regime. FDCs represents frequency distribution of discharges, and can be derived from gauged data, AFDCs allow to introduce confidence intervals for the median AFDC, and to assign return periods to individual AFDCs. But in semiarid environments with ephemeral flows or little basins, where there are environmental problems caused by pollutant discharges, the presence of zeros in a registration creates a discontinuity that makes difficult to model this curves using common distributions. Therefore this work combines the stochastic index model, that relates FDC and AFDC of daily flow series, and that permits to reproduce the mean, the median and variance of AFDC without regard persistency and seasonality of the series for recreate the curve of the non-zero period, with the theory of total probability, that allows to evaluate the percentage of time the river is dry. Next regionalization of information is necessary to apply this model to ungauged stations and a cross-validation procedure for evaluate robustness of results is need. This procedure is applied to a nested catchment in the Lazio region. Here heterogeneity of basins processes appears over a range of space and time scales. Then understanding of statistical and physical relationships that connect the components of the hydrological cycle across these scales is a basic requirement.
NASA Technical Reports Server (NTRS)
Giersch, Louis R.; Knarr, Kevin
2010-01-01
Structures capable of deployment into complex, three-dimensional trusses have well known space technology applications such as the support of spacecraft payloads, communications antennas, radar reflectors, and solar concentrators. Such deployable trusses could also be useful in terrestrial applications such as the rapid establishment of structures in military and emergency service situations, in particular with regard to the deployment of enclosures for habitat or storage. To minimize the time required to deploy such an enclosure, a single arch-shaped truss is preferable to multiple straight trusses arranged vertically and horizontally. To further minimize the time required to deploy such an enclosure, a synchronous deployment with a single degree of freedom is also preferable. One method of synchronizing deployment of a truss is the use of a series of gears; this makes the deployment sequence predictable and testable, allows the truss to have a minimal stowage volume, and the deployed structure exhibits the excellent stiffness-to-mass and strength-to-mass ratios characteristic of a truss. A concept for using gears with varying ratios to deploy a truss into a curved shape has been developed and appears to be compatible with both space technology applications as well as potential use in terrestrial applications such as enclosure deployment. As is the case with other deployable trusses, this truss is formed using rigid elements (e.g., composite tubes) along the edges, one set of diagonal elements composed of either cables or folding/hinged rigid members, and the other set of diagonal elements formed by a continuous cable that is tightened by a motor or hand crank in order to deploy the truss. Gears of varying ratios are used to constrain the deployment to a single degree of freedom, making the deployment synchronous, predictable, and repeatable. The relative sizes of the gears and the relative dimensions of the diagonal elements determine the deployed geometry (e
Composite curved frames for helicopter fuselage structure
NASA Technical Reports Server (NTRS)
Rich, M. J.; Lowry, D. W.
1984-01-01
This paper presents the results of analysis and testing of composite curved frames. A major frame was selected from the UH-60 Black Hawk helicopter and designed as a composite structure. The curved beam effects were expected to increase flange axial stresses and induce transverse bending. A NASTRAN finite element analysis was conducted and the results were used in the design of composite curved frame specimens. Three specimens were fabricated and five static tests were conducted. The NASTRAN analysis and test results are compared for axial, transverse, and Web strains. Results show the curved beam effects are closely predicted by a NASTRAN analysis and the effects increase with loading on the composite frames.
A kill curve for Phanerozoic marine species
NASA Technical Reports Server (NTRS)
Raup, D. M.
1991-01-01
A kill curve for Phanerozoic species is developed from an analysis of the stratigraphic ranges of 17,621 genera, as compiled by Sepkoski. The kill curve shows that a typical species' risk of extinction varies greatly, with most time intervals being characterized by very low risk. The mean extinction rate of 0.25/m.y. is thus a mixture of long periods of negligible extinction and occasional pulses of much higher rate. Because the kill curve is merely a description of the fossil record, it does not speak directly to the causes of extinction. The kill curve may be useful, however, to li inverted question markmit choices of extinction mechanisms.
Titania nanorods curve to lower their energy.
Zhang, Hengzhong; Finnegan, Michael P; Banfield, Jillian F
2013-08-01
Spontaneous formation of curved nanorods is generally unexpected, since curvature introduces strain energy. However, electron microscopy shows that under hydrothermal conditions, some nanorods grown by oriented attachment of small anatase particles on {101} surfaces are curved and dislocation free. Molecular dynamics simulations show that the lattice energy of a curved anatase rod is actually lower than that of a linear rod due to more attractive long-range interatomic Coulombic interactions among atoms in the curved rod. The thermodynamic driving force stemming from lattice energy could be harnessed to produce asymmetric morphologies unexpected from classical Ostwald ripening with unusual shapes and properties. PMID:23794056
Craniofacial reconstruction using rational cubic ball curves.
Majeed, Abdul; Mt Piah, Abd Rahni; Gobithaasan, R U; Yahya, Zainor Ridzuan
2015-01-01
This paper proposes the reconstruction of craniofacial fracture using rational cubic Ball curve. The idea of choosing Ball curve is based on its robustness of computing efficiency over Bezier curve. The main steps are conversion of Digital Imaging and Communications in Medicine (Dicom) images to binary images, boundary extraction and corner point detection, Ball curve fitting with genetic algorithm and final solution conversion to Dicom format. The last section illustrates a real case of craniofacial reconstruction using the proposed method which clearly indicates the applicability of this method. A Graphical User Interface (GUI) has also been developed for practical application. PMID:25880632
Dissociative Recombination without a Curve Crossing
NASA Technical Reports Server (NTRS)
Guberman, Steven L.
1994-01-01
Ab initio calculations show that a curve crossing is not always needed for a high dissociative- recombination cross section. For HeH(+), in which no neutral states cross the ion potential curve, dissociative recombination is driven by the nuclear kinetic-energy operator on adiabatic potential curves. The kinetic-energy derivative operator allows for capture into repulsive curves that are outside of the classical turning points for the nuclear motion. The dominant dissociative route is the C (2)Sigma(+) state leading to H(n = 2) atoms. An analogous mechanism is proposed for the dissociative recombination of H3(+).
Craniofacial Reconstruction Using Rational Cubic Ball Curves
Majeed, Abdul; Mt Piah, Abd Rahni; Gobithaasan, R. U.; Yahya, Zainor Ridzuan
2015-01-01
This paper proposes the reconstruction of craniofacial fracture using rational cubic Ball curve. The idea of choosing Ball curve is based on its robustness of computing efficiency over Bezier curve. The main steps are conversion of Digital Imaging and Communications in Medicine (Dicom) images to binary images, boundary extraction and corner point detection, Ball curve fitting with genetic algorithm and final solution conversion to Dicom format. The last section illustrates a real case of craniofacial reconstruction using the proposed method which clearly indicates the applicability of this method. A Graphical User Interface (GUI) has also been developed for practical application. PMID:25880632
Ab initio yield curve dynamics [rapid communication
NASA Astrophysics Data System (ADS)
Hawkins, Raymond J.; Roy Frieden, B.; D'Anna, Joseph L.
2005-09-01
We derive an equation of motion for interest-rate yield curves by applying a minimum Fisher information variational approach to the implied probability density. By construction, solutions to the equation of motion recover observed bond prices. More significantly, the form of the resulting equation explains the success of the Nelson Siegel approach to fitting static yield curves and the empirically observed modal structure of yield curves. A practical numerical implementation of this equation of motion is found by using the Karhunen Lòeve expansion and Galerkin's method to formulate a reduced-order model of yield curve dynamics.
Analytical investigation of curved steel girder behaviour
NASA Astrophysics Data System (ADS)
Simpson, Michael Donald
Horizontally curved bridges meet an increasing demand for complex highway geometries in congested urban areas. A popular type of curved bridge consists of steel I-girders interconnected by cross-frames and a composite concrete deck slab. Prior to hardening of the concrete deck each I-girder is susceptible to a lateral torsional buckling-type failure. Unlike a straight I-girder, a curved I-girder resists major components of stress resulting from strong axis bending, weak axis bending and warping. The combination of these stresses reduce the available strength of a curved girder versus that of an equivalent straight girder. Experiments demonstrating the ultimate strength characteristics of curved girders are few in number. Of the available experimental research, few studies have used full scale-tests and boundary conditions indicative of those found in an actual bridge structure. Unlike straight girders, curved girders are characterized by nonlinear out-of-plane deformations which, depending upon the magnitude of curvature, may occur at very low load levels. Because of the inherent nonlinear behaviour, some have questioned the application of the term lateral torsional buckling to curved girders; rather curved girders behave in a manner consistent with a deflection-amplification problem. Even with the advent of sophisticated analytical techniques, there is a glaring void in the documented literature regarding calibration of these techniques with known experimental curved girder behaviour. Presented here is an analytical study of the nonlinear modelling of curved steel girders and bridges. This is accomplished by incorporating large deflection and nonlinear material behaviour into three dimensional finite element models generated using the program ANSYS. Emphasis is placed on the calibration of the finite method with known experimental ultimate strength data. It is demonstrated that accurate predictions of load deformation and ultimate strength are attainable via the
Forgetting Curves: Implications for Connectionist Models
ERIC Educational Resources Information Center
Sikstrom, Sverker
2002-01-01
Forgetting in long-term memory, as measured in a recall or a recognition test, is faster for items encoded more recently than for items encoded earlier. Data on forgetting curves fit a power function well. In contrast, many connectionist models predict either exponential decay or completely flat forgetting curves. This paper suggests a…
Forces in the complex octonion curved space
NASA Astrophysics Data System (ADS)
Weng, Zi-Hua
2016-04-01
The paper aims to extend major equations in the electromagnetic and gravitational theories from the flat space into the complex octonion curved space. Maxwell applied simultaneously the quaternion analysis and vector terminology to describe the electromagnetic theory. It inspires subsequent scholars to study the electromagnetic and gravitational theories with the complex quaternions/octonions. Furthermore Einstein was the first to depict the gravitational theory by means of tensor analysis and curved four-space-time. Nowadays some scholars investigate the electromagnetic and gravitational properties making use of the complex quaternion/octonion curved space. From the orthogonality of two complex quaternions, it is possible to define the covariant derivative of the complex quaternion curved space, describing the gravitational properties in the complex quaternion curved space. Further it is possible to define the covariant derivative of the complex octonion curved space by means of the orthogonality of two complex octonions, depicting simultaneously the electromagnetic and gravitational properties in the complex octonion curved space. The result reveals that the connection coefficient and curvature of the complex octonion curved space will exert an influence on the field strength and field source of the electromagnetic and gravitational fields, impacting the linear momentum, angular momentum, torque, energy, and force and so forth.
Symmetry Properties of Potentiometric Titration Curves.
ERIC Educational Resources Information Center
Macca, Carlo; Bombi, G. Giorgio
1983-01-01
Demonstrates how the symmetry properties of titration curves can be efficiently and rigorously treated by means of a simple method, assisted by the use of logarithmic diagrams. Discusses the symmetry properties of several typical titration curves, comparing the graphical approach and an explicit mathematical treatment. (Author/JM)
Electrical-Discharge Machining Of Curved Passages
NASA Technical Reports Server (NTRS)
Guirguis, Kamal S.
1993-01-01
Electrical-discharge machining (EDM) used to cut deep hole with bends. EDM process done with articulating segmented electrode. Originally straight, electrode curved as it penetrates part, forming long, smoothly curving hole. After hole cut, honed with slurry to remove thin layer of recast metal created by EDM. Breakage of tools, hand deburring, and drilling debris eliminated.
Phenomenological modelling of eclipsing system light curves
NASA Astrophysics Data System (ADS)
Mikulášek, Zdeněk
2015-12-01
Context. The observed light curves of most eclipsing binaries and stars with transiting planets can be described well and interpreted by current advanced physical models that also allow for determining many of the physical parameters of eclipsing systems. However, for several common practical tasks, there is no need to know the detailed physics of a variable star, but only the shapes of their light curves or other phase curves. Aims: We present a set of phenomenological models for the light curves of eclipsing systems. Methods: We express the observed light curves of eclipsing binaries and stars, which are transited by their exoplanets orbiting in circular trajectories, by a sum of special, analytical, few-parameter functions that enable fitting their light curves with an accuracy of better than 1%. The proposed set of phenomenological models of eclipsing variable light curves were then tested on several real systems. For XY Bootis, we also give a detailed comparison of the results obtained using our phenomenological modelling with those found using available physical models. Results: We demonstrate that the proposed phenomenological models of transiting exoplanet and eclipsing binary light curves applied to ground-based photometric observations yield results compatible with those obtained by applying more complex physical models. Conclusions: The suggested phenomenological modelling appears useful for solving a number of common tasks in the field of eclipsing variable research.
Parallel Curves: Getting There and Getting Back
ERIC Educational Resources Information Center
Agnew, A. F.; Mathews, J. H.
2006-01-01
This note takes up the issue of parallel curves while illustrating the utility of "Mathematica" in computations. This work complements results presented earlier. The presented treatment, considering the more general case of parametric curves, provides an analysis of the appearance of cusp singularities, and emphasizes the utility of symbolic…
DELightcurveSimulation: Light curve simulation code
NASA Astrophysics Data System (ADS)
Connolly, Samuel D.
2016-02-01
DELightcurveSimulation simulates light curves with any given power spectral density and any probability density function, following the algorithm described in Emmanoulopoulos et al. (2013). The simulated products have exactly the same variability and statistical properties as the observed light curves. The code is a Python implementation of the Mathematica code provided by Emmanoulopoulos et al.
The Informative Analysis of Individual Trend Curves
ERIC Educational Resources Information Center
McDonald, Roderick P.
2004-01-01
Additive and non-additive models for an individual trend curve are examined, and five methods for fitting these to a set of individuals are described. It is suggested that classical fitting methods are more informative than latent curve methods, and commonly preferable. A limited study of the effect of time-structure is reported, and results on…
Mixture Modeling of Individual Learning Curves
ERIC Educational Resources Information Center
Streeter, Matthew
2015-01-01
We show that student learning can be accurately modeled using a mixture of learning curves, each of which specifies error probability as a function of time. This approach generalizes Knowledge Tracing [7], which can be viewed as a mixture model in which the learning curves are step functions. We show that this generality yields order-of-magnitude…
Measuring Model Rocket Engine Thrust Curves
ERIC Educational Resources Information Center
Penn, Kim; Slaton, William V.
2010-01-01
This paper describes a method and setup to quickly and easily measure a model rocket engine's thrust curve using a computer data logger and force probe. Horst describes using Vernier's LabPro and force probe to measure the rocket engine's thrust curve; however, the method of attaching the rocket to the force probe is not discussed. We show how a…
CURV 3: Characteristics and mission applications
NASA Astrophysics Data System (ADS)
Perkins, W. W.; Brady, L. K.
1984-03-01
The Cable-Controlled Underwater Recovery Vehicle (CURV) program was begun by NOSC for the specific purpose of developing economical systems to recover test ordnance at NOSC's Long Beach and San Clemente Island test ranges. CURV 3 is the latest in this series of tethered, unmanned, remotely controlled vehicles and its present capabilities far exceed the original CURV 1. Originally conceived for use as a search and recovery vehicle, CURV has evolved into a versatile and easily adaptable multipurpose work vehicle capable of performing search and recovery tasks as well as pursuing test, evaluation, exploration, and work projects. Basically, CURV is a composite of integrated subsystems including such items as propulsion, search and navigation, optics, hydraulics, and tools. Because it is unmanned and does not require life support or other complex support systems, CURV is able to perform most undersea tasks more economically and efficiently than maned systems. Also, since it is powered and controlled from the surface, CURV has a continuous, unlimited operating capability. Under emergency conditions, the vehicle can operate to 10,000-foot depths. CURV can be easily transported to any spot in the world. Upon arrival of the vehicle, control van, cable, and support gear can be mounted on a suitable ship of opportunity.
ABR frequency tuning curves in dolphins.
Supin, A Y; Popov, V V; Klishin, V O
1993-11-01
Tone-tone masking was used to determine auditory brain-stem response tuning curves in dolphins (Tursiops truncatus) in a simultaneous-masking paradigm. The Q10 of the curves was as large as 16-19 in the frequency range 64-128 kHz. In the range 45-16 kHz, Q10 decreased proportionally to the frequency with the bandwidth of the curves being constant, about 3.5-4 kHz at the 10-dB level. Tuning curves below 45 kHz are supposed to reflect broad spectral bandwidth of the probe's effective part which is no longer than 0.5 ms, irrespective of actual probe duration. Tuning curves above 64 kHz are supposed to reflect the real frequency tuning of the dolphin's auditory system. PMID:8263842
Modelling asteroid brightness variations. II - The interpretability of light curves and phase curves
NASA Technical Reports Server (NTRS)
Karttunen, H.; Bowell, E.
1989-01-01
Light curves and phase curves have been computed for various asteroid models using the Lumme-Bowell (1981) scattering law. The effects of the scattering parameters on light curves were found to be almost negligible for homogeneous surfaces. The effects on phase curves were more distinct, but changing any of the scattering parameters affects the phase curves in a very similar way, making it impossible to find a unique set of parameter values corresponding to a given phase curve. Light curve amplitudes, on the other hand, depend very strongly on body shape. At least in the case of a triaxial ellipsoid it is possible to determine the axial ratios. Some observed irregularities of light curves can also be modelled easily, but the uniqueness of such models is far from obvious.
"Universal" Recession Curves and their Geomorphological Roots
NASA Astrophysics Data System (ADS)
Marani, M.; Biswal, B.
2011-12-01
The basic structural organization of channel networks, and of the connected hillslopes, have been shown to be intimately linked to basin responses to rainfall events, leading to geomorphological theories of the hydrologic response. Here, We identify a previously undetected link between the river network morphology and key recession curves properties. We show that the power-law exponent of -dQ/dt vs. Q curves is related to the power-law exponent of N(l) vs. G(l) curves (which we show to be connected to Hack's law), where l is the downstream distance from the channel heads, N(l) is the number of channel reaches exactly located at a distance l from their channel head, and G(l) is the total length of the network located at a distance greater or equal to l from channel heads. We then generalize the power-law expressions of recession curves, to identify "universal" curves, independent of the initial moisture conditions and of basin area, by making the -dQ/dt vs. Q curve non-dimensional using an index discharge representative of initial moisture conditions. We subsequently rescale the geomorphic recession curve, N(l) vs. G(l), producing a collapse of the geomorphic recession curves constructed from the DTM's of 67 US study basins. Finally, by use of the specific discharge u = Q/A, we link the two previous results and define the specific recession curves, whose collapse across basins within homogeneous geographical areas lends further, decisive, support to the notion that the statistical properties of observational recession curves bear the signature of the geomorphological structure of the networks producing them.
Investigation of learning and experience curves
Krawiec, F.; Thornton, J.; Edesess, M.
1980-04-01
The applicability of learning and experience curves for predicting future costs of solar technologies is assessed, and the major test case is the production economics of heliostats. Alternative methods for estimating cost reductions in systems manufacture are discussed, and procedures for using learning and experience curves to predict costs are outlined. Because adequate production data often do not exist, production histories of analogous products/processes are analyzed and learning and aggregated cost curves for these surrogates estimated. If the surrogate learning curves apply, they can be used to estimate solar technology costs. The steps involved in generating these cost estimates are given. Second-generation glass-steel and inflated-bubble heliostat design concepts, developed by MDAC and GE, respectively, are described; a costing scenario for 25,000 units/yr is detailed; surrogates for cost analysis are chosen; learning and aggregate cost curves are estimated; and aggregate cost curves for the GE and MDAC designs are estimated. However, an approach that combines a neoclassical production function with a learning-by-doing hypothesis is needed to yield a cost relation compatible with the historical learning curve and the traditional cost function of economic theory.
Three-body choreographies in given curves
NASA Astrophysics Data System (ADS)
Ozaki, Hiroshi; Fukuda, Hiroshi; Fujiwara, Toshiaki
2009-10-01
As shown by Johannes Kepler in 1609, in the two-body problem, the shape of the orbit, a given ellipse, and a given non-vanishing constant angular momentum determine the motion of the planet completely. Even in the three-body problem, in some cases, the shape of the orbit, conservation of the center of mass and a constant of motion (the angular momentum or the total energy) determine the motion of the three bodies. We show, by a geometrical method, that choreographic motions, in which equal mass three bodies chase each other around the same curve, will be uniquely determined for the following two cases. (i) Convex curves that have point symmetry and non-vanishing angular momentum are given. (ii) Eight-shaped curves which are similar to the curve for the figure-eight solution and the energy constant are given. The reality of the motion should be tested whether the motion satisfies an equation of motion or not. Extensions of the method for generic curves are shown. The extended methods are applicable to generic curves which do not have point symmetry. Each body may have its own curve and its own non-vanishing masses.
Are Driving and Overtaking on Right Curves More Dangerous than on Left Curves?
Othman, Sarbaz; Thomson, Robert; Lannér, Gunnar
2010-01-01
It is well known that crashes on horizontal curves are a cause for concern in all countries due to the frequency and severity of crashes at curves compared to road tangents. A recent study of crashes in western Sweden reported a higher rate of crashes in right curves than left curves. To further understand this result, this paper reports the results of novel analyses of the responses of vehicles and drivers during negotiating and overtaking maneuvers on curves for right hand traffic. The overall objectives of the study were to find road parameters for curves that affect vehicle dynamic responses, to analyze these responses during overtaking maneuvers on curves, and to link the results with driver behavior for different curve directions. The studied road features were speed, super-elevation, radius and friction including their interactions, while the analyzed vehicle dynamic factors were lateral acceleration and yaw angular velocity. A simulation program, PC-Crash, has been used to simulate road parameters and vehicle response interaction in curves. Overtaking maneuvers have been simulated for all road feature combinations in a total of 108 runs. Analysis of variances (ANOVA) was performed, using two sided randomized block design, to find differences in vehicle responses for the curve parameters. To study driver response, a field test using an instrumented vehicle and 32 participants was reviewed as it contained longitudinal speed and acceleration data for analysis. The simulation results showed that road features affect overtaking performance in right and left curves differently. Overtaking on right curves was sensitive to radius and the interaction of radius with road condition; while overtaking on left curves was more sensitive to super-elevation. Comparisons of lateral acceleration and yaw angular velocity during these maneuvers showed different vehicle response configurations depending on curve direction and maneuver path. The field test experiments also showed
Optoacoustic endoscopy in curved scanning mode
NASA Astrophysics Data System (ADS)
He, Hailong; Buehler, Andreas; Ntziachristos, Vasilis
2016-03-01
Optoacoustic technique has been shown to resolve anatomical, functional and molecular features at depths that go beyond the reach of epi-illumination optical microscopy offering new opportunities for endoscopic imaging. Herein, we interrogate the merits of optoacoustic endoscopy implemented by translating a sound detector in linear or curved geometries. The linear and curved detection geometries are achieved by employing an intravascular ultrasound transducer (IVUS) within a plastic guide shaped to a line or a curve. This concept could be used together with optical endoscopes to yield hybrid optical and optoacoustic imaging.
Aq Psc Analysis of New Light Curves
NASA Astrophysics Data System (ADS)
Yamasaki, Atsuma
2005-04-01
New BV light curves of the A-type W UMa star AQ Psc (P = 0.476d) have been observed and are described. A few times of minimum light are obtained and the ephemeris is improved. The light curves are analyzed for the binary parameters with a light curve synthesis method. Combining the results with Lu and Rucinski’s spectroscopic mass ratio we determined the masses and radii of the components: M 1 = 1.69M ⊙, M 2 = 0.38M ⊙, R 1 = 1.77R ⊙, and R 2 = 0.89R ⊙.
Replication and Analysis of Ebbinghaus’ Forgetting Curve
Murre, Jaap M. J.; Dros, Joeri
2015-01-01
We present a successful replication of Ebbinghaus’ classic forgetting curve from 1880 based on the method of savings. One subject spent 70 hours learning lists and relearning them after 20 min, 1 hour, 9 hours, 1 day, 2 days, or 31 days. The results are similar to Ebbinghaus' original data. We analyze the effects of serial position on forgetting and investigate what mathematical equations present a good fit to the Ebbinghaus forgetting curve and its replications. We conclude that the Ebbinghaus forgetting curve has indeed been replicated and that it is not completely smooth but most probably shows a jump upwards starting at the 24 hour data point. PMID:26148023
Cosmic string lensing and closed timelike curves
NASA Astrophysics Data System (ADS)
Shlaer, Benjamin; Tye, S.-H. Henry
2005-08-01
In an analysis of the gravitational lensing by two relativistic cosmic strings, we argue that the formation of closed timelike curves proposed by Gott is unstable in the presence of particles (e.g. the cosmic microwave background radiation). Because of the attractorlike behavior of the closed timelike curve, we argue that this instability is very generic. A single graviton or photon in the vicinity, no matter how soft, is sufficient to bend the strings and prevent the formation of closed timelike curves. We also show that the gravitational lensing due to a moving cosmic string is enhanced by its motion, not suppressed.
Roadblocks on the kill curve: Testing the Raup hypothesis
Poag, C.W.
1997-01-01
The documented presence of two large (???100-km diameter), possibly coeval impact craters of late Eocene age, requires modification of the impact-kill curve proposed by David M. Raup. Though the estimated meteorite size for each crater alone is large enough to have produced considerable global environmental stress, no horizons of mass mortality or pulsed extinction are known to be associated with either crater or their ejecta deposits. Thus, either there is no fixed relationship between extinction magnitude and crater diameter, or a meteorite that would produce a crater of >100-km diameter is required to raise extinction rates significantly above a ???5% background level. Both impacts took place ???1-2 m.y. before the "Terminal Eocene Event"( =early Oligocene pulsed extinction). Their collective long-term environmental effects, however, may have either delayed that extinction pulse or produced threshold conditions necessary for it to take place.
On the characterization of flowering curves using Gaussian mixture models.
Proïa, Frédéric; Pernet, Alix; Thouroude, Tatiana; Michel, Gilles; Clotault, Jérémy
2016-08-01
In this paper, we develop a statistical methodology applied to the characterization of flowering curves using Gaussian mixture models. Our study relies on a set of rosebushes flowering data, and Gaussian mixture models are mainly used to quantify the reblooming properties of each one. In this regard, we also suggest our own selection criterion to take into account the lack of symmetry of most of the flowering curves. Three classes are created on the basis of a principal component analysis conducted on a set of reblooming indicators, and a subclassification is made using a longitudinal k-means algorithm which also highlights the role played by the precocity of the flowering. In this way, we obtain an overview of the correlations between the features we decided to retain on each curve. In particular, results suggest the lack of correlation between reblooming and flowering precocity. The pertinent indicators obtained in this study will be a first step towards the comprehension of the environmental and genetic control of these biological processes. PMID:27113781
Solid-state curved focal plane arrays
NASA Technical Reports Server (NTRS)
Nikzad, Shouleh (Inventor); Hoenk, Michael (Inventor); Jones, Todd (Inventor)
2010-01-01
The present invention relates to curved focal plane arrays. More specifically, the present invention relates to a system and method for making solid-state curved focal plane arrays from standard and high-purity devices that may be matched to a given optical system. There are two ways to make a curved focal plane arrays starting with the fully fabricated device. One way, is to thin the device and conform it to a curvature. A second way, is to back-illuminate a thick device without making a thinned membrane. The thick device is a special class of devices; for example devices fabricated with high purity silicon. One surface of the device (the non VLSI fabricated surface, also referred to as the back surface) can be polished to form a curved surface.
Transmission of wave energy in curved ducts
NASA Technical Reports Server (NTRS)
Rostafinski, W.
1973-01-01
A formation of wave energy flow was developed for motion in curved ducts. A parametric study over a range of frequencies determined the ability of circular bends to transmit energy for the case of perfectly rigid walls.
Infiltration formulas by curve number procedure.
Chen, C.-L.
1982-01-01
The Soil Conservation Service (SCS) curve number procedure for estimating runoff volume is examined in terms of the validity and applicability of the derived infiltration equations. -from ASCE Publications Abstracts
Modeling Type IIn Supernova Light Curves
NASA Astrophysics Data System (ADS)
De La Rosa, Janie; Roming, Peter; Fryer, Chris
2016-01-01
We present near-by Type IIn supernovae observed with Swift's Ultraviolet/Optical Telescope (UVOT). Based on the diversity of optical light curve properties, this Type II subclass is commonly referred to as heterogeneous. At the time of discovery, our IIn sample is ~ 2 magnitudes brighter at ultraviolet wavelengths than at optical wavelengths, and ultraviolet brightness decays faster than the optical brightness. We use a semi-analytical supernova (SN) model to better understand our IIn observations, and focus on matching specific observed light curves features, i.e peak luminosity and decay rate. The SN models are used to study the effects of initial SN conditions on early light curves, and to show the extent of the "uniqueness" problem in SN light curves. We gratefully acknowledge the contributions from members of the Swift UVOT team, the NASA astrophysics archival data analysis program, and the NASA Swift guest investigator program.
The Kinked Demand Curve When Demand Shifts.
ERIC Educational Resources Information Center
Frasco, Gregg P.
1993-01-01
Reviews recent research into the theory of the kinked demand curve in economics. Applies this theory to economic concepts such as marginal cost and price flexibility. Discusses the implications for corporations and government policymakers. (CFR)
Classification of ASKAP Vast Radio Light Curves
NASA Technical Reports Server (NTRS)
Rebbapragada, Umaa; Lo, Kitty; Wagstaff, Kiri L.; Reed, Colorado; Murphy, Tara; Thompson, David R.
2012-01-01
The VAST survey is a wide-field survey that observes with unprecedented instrument sensitivity (0.5 mJy or lower) and repeat cadence (a goal of 5 seconds) that will enable novel scientific discoveries related to known and unknown classes of radio transients and variables. Given the unprecedented observing characteristics of VAST, it is important to estimate source classification performance, and determine best practices prior to the launch of ASKAP's BETA in 2012. The goal of this study is to identify light curve characterization and classification algorithms that are best suited for archival VAST light curve classification. We perform our experiments on light curve simulations of eight source types and achieve best case performance of approximately 90% accuracy. We note that classification performance is most influenced by light curve characterization rather than classifier algorithm.
Bounded Population Growth: A Curve Fitting Lesson.
ERIC Educational Resources Information Center
Mathews, John H.
1992-01-01
Presents two mathematical methods for fitting the logistic curve to population data supplied by the U.S. Census Bureau utilizing computer algebra software to carry out the computations and plot graphs. (JKK)
The Pressure Curve for a Rubber Balloon.
ERIC Educational Resources Information Center
Merritt, D. R.; Weinhaus, F.
1978-01-01
Derives an equation relating the internal pressure of a rubber balloon to its radius. Shows that the theoretical pressure curve is experimentally verifiable, and discusses the problem of equilibrium configuration of two interconnected ballons. (Author/GA)
Spline Curves, Wire Frames and Bvalue
NASA Technical Reports Server (NTRS)
Smith, L.; Munchmeyer, F.
1985-01-01
The methods that were developed for wire-frame design are described. The principal tools for control of a curve during interactive design are mathematical ducks. The simplest of these devices is an analog of the draftsman's lead weight that he uses to control a mechanical spline also create Ducks for controlling differential and integral properties of curves were created. Other methods presented include: constructing the end of a Bezier polygon to gain quick and reasonably confident control of the end tangent vector, end curvature and end torsion; keeping the magnitude of unwanted curvature oscillations within tolerance; constructing the railroad curves that appear in many engineering design problems; and controlling the frame to minimize errors at mesh points and to optimize the shapes of the curve elements.
Estimating power curves of flying vertebrates.
Rayner, J M
1999-12-01
The power required for flight in any flying animal is a function of flight speed. The power curve that describes this function has become an icon of studies of flight mechanics and physiology because it encapsulates the accessible animal's flight performance. The mechanical or aerodynamic power curve, describing the increase in kinetic energy of the air due to the passage of the bird, is necessarily U-shaped, for aerodynamic reasons, and can be estimated adequately by lifting-line theory. Predictions from this and related models agree well with measured mechanical work in flight and with results from flow visualization experiments. The total or metabolic power curve also includes energy released by the animal as heat, and is more variable in shape. These curves may be J-shaped for smaller birds and bats, but are difficult to predict theoretically owing to uncertainty about internal physiological processes and the efficiency of the flight muscles. The limitations of some existing models aiming to predict metabolic power curves are considered. The metabolic power curve can be measured for birds or bats flying in wind tunnels at controlled speeds. Simultaneous determination in European starlings Sturnus vulgaris of oxygen uptake, total metabolic rate (using labelled isotopes), aerodynamic power output and heat released (using digital video thermography) enable power curves to be determined with confidence; flight muscle efficiency is surprisingly low (averaging 15-18 %) and increases moderately with flight speed, so that the metabolic power curve is shallower than predicted by models. Accurate knowledge of the power curve is essential since extensive predictions of flight behaviour have been based upon it. The hypothesis that the power curve may not in fact exist, in the sense that the cost of flight may not be perceived by a bird as a continuous smooth function of air speed, is advanced but has not yet formally been tested. This hypothesis is considered together with
Deformability curve for K18 steel
Pospiech, J.
1999-12-01
The problem of the best utilization of plasticity in plastic working processes of metals, at low resistance to deformation and maximum utilization of capacity of installations has gained great importance, especially in recent years. Determination of plasticity of materials by the method of Kolmogorow is described. Variation of the stress factor for several plastic working processes is also described. Tests to plot the deformability curve (also referred to as reserve of plasticity curve) were selected and proved.
Anomalies in curved spacetime at finite temperature
Boschi-Filho, H. Departamento de Fisica e Quimica, Universidade Estadual Paulista, Campus de Guaratingueta, 12500 Guaratingueta, Caixa Postal 205 Sao Paulo ); Natividade, C.P. )
1992-12-15
We discuss the problem of the breakdown of conformal and gauge symmetries at finite temperature in curved-spacetime background, when the changes in the background are gradual, in order to have a well-defined quantum field theory at finite temperature. We obtain the expressions for Seeley's coefficients and the heat-kernel expansion in this regime. As applications, we consider the self-interacting [lambda][phi][sup 4] and chiral Schwinger models in curved backgrounds at finite temperature.
Learning curves in health professions education.
Pusic, Martin V; Boutis, Kathy; Hatala, Rose; Cook, David A
2015-08-01
Learning curves, which graphically show the relationship between learning effort and achievement, are common in published education research but are not often used in day-to-day educational activities. The purpose of this article is to describe the generation and analysis of learning curves and their applicability to health professions education. The authors argue that the time is right for a closer look at using learning curves-given their desirable properties-to inform both self-directed instruction by individuals and education management by instructors.A typical learning curve is made up of a measure of learning (y-axis), a measure of effort (x-axis), and a mathematical linking function. At the individual level, learning curves make manifest a single person's progress towards competence including his/her rate of learning, the inflection point where learning becomes more effortful, and the remaining distance to mastery attainment. At the group level, overlaid learning curves show the full variation of a group of learners' paths through a given learning domain. Specifically, they make overt the difference between time-based and competency-based approaches to instruction. Additionally, instructors can use learning curve information to more accurately target educational resources to those who most require them.The learning curve approach requires a fine-grained collection of data that will not be possible in all educational settings; however, the increased use of an assessment paradigm that explicitly includes effort and its link to individual achievement could result in increased learner engagement and more effective instructional design. PMID:25806621
TS - Dean interactions in curved channel flow
NASA Technical Reports Server (NTRS)
Singer, Bart A.; Zang, Thomas A.; Erlebacher, Gordon
1990-01-01
A weakly nonlinear theory is developed to study the interaction of TS waves and Dean vortices in curved channel flow. The prediction obtained from the theory agree well with results obtained from direct numerical simulations of curved channel flow, especially for low amplitude disturbances. At low Reynolds numbers the wave interaction is generally stabilizing to both disturbances, though as the Reynolds number increases, many linearly unstable TS waves are further destabilized by the presence of Dean vortices.
Regression models for convex ROC curves.
Lloyd, C J
2000-09-01
The performance of a diagnostic test is summarized by its receiver operating characteristic (ROC) curve. Under quite natural assumptions about the latent variable underlying the test, the ROC curve is convex. Empirical data on a test's performance often comes in the form of observed true positive and false positive relative frequencies under varying conditions. This paper describes a family of regression models for analyzing such data. The underlying ROC curves are specified by a quality parameter delta and a shape parameter mu and are guaranteed to be convex provided delta > 1. Both the position along the ROC curve and the quality parameter delta are modeled linearly with covariates at the level of the individual. The shape parameter mu enters the model through the link functions log(p mu) - log(1 - p mu) of a binomial regression and is estimated either by search or from an appropriate constructed variate. One simple application is to the meta-analysis of independent studies of the same diagnostic test, illustrated on some data of Moses, Shapiro, and Littenberg (1993). A second application, to so-called vigilance data, is given, where ROC curves differ across subjects and modeling of the position along the ROC curve is of primary interest. PMID:10985227
Piecewise power laws in individual learning curves.
Donner, Yoni; Hardy, Joseph L
2015-10-01
The notion that human learning follows a smooth power law (PL) of diminishing gains is well-established in psychology. This characteristic is observed when multiple curves are averaged, potentially masking more complex dynamics underpinning the curves of individual learners. Here, we analyzed 25,280 individual learning curves, each comprising 500 measurements of cognitive performance taken from four cognitive tasks. A piecewise PL (PPL) model explained the individual learning curves significantly better than a single PL, controlling for model complexity. The PPL model allows for multiple PLs connected at different points in the learning process. We also explored the transition dynamics between PL curve component pieces. Performance in later pieces typically surpassed that in earlier pieces, after a brief drop in performance at the transition point. The transition rate was negatively associated with age, even after controlling for overall performance. Our results suggest at least two processes at work in individual learning curves: locally, a gradual, smooth improvement, with diminishing gains within a specific strategy, which is modeled well as a PL; and globally, a discrete sequence of strategy shifts, in which each strategy is better in the long term than the ones preceding it. The piecewise extension of the classic PL of practice has implications for both individual skill acquisition and theories of learning. PMID:25711183
Comparative power curves in bird flight.
Tobalske, B W; Hedrick, T L; Dial, K P; Biewener, A A
2003-01-23
The relationship between mechanical power output and forward velocity in bird flight is controversial, bearing on the comparative physiology and ecology of locomotion. Applied to flying birds, aerodynamic theory predicts that mechanical power should vary as a function of forward velocity in a U-shaped curve. The only empirical test of this theory, using the black-billed magpie (Pica pica), suggests that the mechanical power curve is relatively flat over intermediate velocities. Here, by integrating in vivo measurements of pectoralis force and length change with quasi-steady aerodynamic models developed using data on wing and body movement, we present mechanical power curves for cockatiels (Nymphicus hollandicus) and ringed turtle-doves (Streptopelia risoria). In contrast to the curve reported for magpies, the power curve for cockatiels is acutely concave, whereas that for doves is intermediate in shape and shows higher mass-specific power output at most speeds. We also find that wing-beat frequency and mechanical power output do not necessarily share minima in flying birds. Thus, aspects of morphology, wing kinematics and overall style of flight can greatly affect the magnitude and shape of a species' power curve. PMID:12540899
Probing exoplanet clouds with optical phase curves.
Muñoz, Antonio García; Isaak, Kate G
2015-11-01
Kepler-7b is to date the only exoplanet for which clouds have been inferred from the optical phase curve--from visible-wavelength whole-disk brightness measurements as a function of orbital phase. Added to this, the fact that the phase curve appears dominated by reflected starlight makes this close-in giant planet a unique study case. Here we investigate the information on coverage and optical properties of the planet clouds contained in the measured phase curve. We generate cloud maps of Kepler-7b and use a multiple-scattering approach to create synthetic phase curves, thus connecting postulated clouds with measurements. We show that optical phase curves can help constrain the composition and size of the cloud particles. Indeed, model fitting for Kepler-7b requires poorly absorbing particles that scatter with low-to-moderate anisotropic efficiency, conclusions consistent with condensates of silicates, perovskite, and silica of submicron radii. We also show that we are limited in our ability to pin down the extent and location of the clouds. These considerations are relevant to the interpretation of optical phase curves with general circulation models. Finally, we estimate that the spherical albedo of Kepler-7b over the Kepler passband is in the range 0.4-0.5. PMID:26489652
Geometric Observers for Dynamically Evolving Curves
Niethammer, Marc; Vela, Patricio A.; Tannenbaum, Allen
2009-01-01
This paper proposes a deterministic observer design for visual tracking based on nonparametric implicit (level-set) curve descriptions. The observer is continuous discrete with continuous-time system dynamics and discrete-time measurements. Its state-space consists of an estimated curve position augmented by additional states (e.g., velocities) associated with every point on the estimated curve. Multiple simulation models are proposed for state prediction. Measurements are performed through standard static segmentation algorithms and optical-flow computations. Special emphasis is given to the geometric formulation of the overall dynamical system. The discrete-time measurements lead to the problem of geometric curve interpolation and the discrete-time filtering of quantities propagated along with the estimated curve. Interpolation and filtering are intimately linked to the correspondence problem between curves. Correspondences are established by a Laplace-equation approach. The proposed scheme is implemented completely implicitly (by Eulerian numerical solutions of transport equations) and thus naturally allows for topological changes and subpixel accuracy on the computational grid. PMID:18421113
Updated U.S. Geothermal Supply Curve
Augustine, C.; Young, K. R.; Anderson, A.
2010-02-01
This paper documents the approach used to update the U.S. geothermal supply curve. The analysis undertaken in this study estimates the supply of electricity generation potential from geothermal resources in the United States and the levelized cost of electricity (LCOE), capital costs, and operating and maintenance costs associated with developing these geothermal resources. Supply curves were developed for four categories of geothermal resources: identified hydrothermal (6.4 GWe), undiscovered hydrothermal (30.0 GWe), near-hydrothermal field enhanced geothermal systems (EGS) (7.0 GWe) and deep EGS (15,900 GWe). Two cases were considered: a base case and a target case. Supply curves were generated for each of the four geothermal resource categories for both cases. For both cases, hydrothermal resources dominate the lower cost range of the combined geothermal supply curve. The supply curves indicate that the reservoir performance improvements assumed in the target case could significantly lower EGS costs and greatly increase EGS deployment over the base case.
Learning curves in classification with microarray data.
Hess, Kenneth R; Wei, Caimiao
2010-02-01
The performance of many repeated tasks improves with experience and practice. This improvement tends to be rapid initially and then decreases. The term "learning curve" is often used to describe the phenomenon. In supervised machine learning, the performance of classification algorithms often increases with the number of observations used to train the algorithm. We use progressively larger samples of observations to train the algorithm and then plot performance against the number of training observations. This yields the familiar negatively accelerating learning curve. To quantify the learning curve, we fit inverse power law models to the progressively sampled data. We fit such learning curves to four large clinical cancer genomic datasets, using three classifiers (diagonal linear discriminant analysis, K-nearest-neighbor with three neighbors, and support vector machines) and four values for the number of top genes included (5, 50, 500, 5,000). The inverse power law models fit the progressively sampled data reasonably well and showed considerable diversity when multiple classifiers are applied to the same data. Some classifiers showed rapid and continued increase in performance as the number of training samples increased, while others showed little if any improvement. Assessing classifier efficiency is particularly important in genomic studies since samples are so expensive to obtain. It is important to employ an algorithm that uses the predictive information efficiently, but with a modest number of training samples (>50), learning curves can be used to assess the predictive efficiency of classification algorithms. PMID:20172367
Probing exoplanet clouds with optical phase curves
Muñoz, Antonio García; Isaak, Kate G.
2015-01-01
Kepler-7b is to date the only exoplanet for which clouds have been inferred from the optical phase curve—from visible-wavelength whole-disk brightness measurements as a function of orbital phase. Added to this, the fact that the phase curve appears dominated by reflected starlight makes this close-in giant planet a unique study case. Here we investigate the information on coverage and optical properties of the planet clouds contained in the measured phase curve. We generate cloud maps of Kepler-7b and use a multiple-scattering approach to create synthetic phase curves, thus connecting postulated clouds with measurements. We show that optical phase curves can help constrain the composition and size of the cloud particles. Indeed, model fitting for Kepler-7b requires poorly absorbing particles that scatter with low-to-moderate anisotropic efficiency, conclusions consistent with condensates of silicates, perovskite, and silica of submicron radii. We also show that we are limited in our ability to pin down the extent and location of the clouds. These considerations are relevant to the interpretation of optical phase curves with general circulation models. Finally, we estimate that the spherical albedo of Kepler-7b over the Kepler passband is in the range 0.4–0.5. PMID:26489652
NASA Astrophysics Data System (ADS)
Linnell, A. P.
1986-01-01
This paper studies various models which attempt to explain light curves and color curves for eclipsing W Ursae Majoris stars of type W. Observed color curves for VW Cephei are in disagreement with the Mullan starspot model to explain W-type light curves. An alternative starspot model, with starspots located on the averted hemisphere of the larger star, represents the light curves and color curves for 1980 August 21 with good accuracy. The observed light curves and color curves of VW Cephei agree with theoretical curves for a Rucinski hot secondary model. A single spot, added to the underlying hot secondary model, provides a reasonably accurate representation of UBVRI photometric data.
Lin, Maozi; Wang, Zhiwei; He, Lingchao; Xu, Kang; Cheng, Dongliang; Wang, Genxuan
2015-01-01
Photosynthesis-irradiance (PI) curves are extensively used in field and laboratory research to evaluate the photon-use efficiency of plants. However, most existing models for PI curves focus on the relationship between the photosynthetic rate (Pn) and photosynthetically active radiation (PAR), and do not take account of the influence of environmental factors on the curve. In the present study, we used a new non-competitive inhibited Michaelis-Menten model (NIMM) to predict the co-variation of Pn, PAR, and the relative pollution index (I). We then evaluated the model with published data and our own experimental data. The results indicate that the Pn of plants decreased with increasing I in the environment and, as predicted, were all fitted well by the NIMM model. Therefore, our model provides a robust basis to evaluate and understand the influence of environmental pollution on plant photosynthesis. PMID:26561863
Mathematical design of a highway exit curve
NASA Astrophysics Data System (ADS)
Pakdemirli, Mehmet
2016-01-01
A highway exit curve is designed under the assumption that the tangential and normal components of the acceleration of the vehicle remain constant throughout the path. Using fundamental principles of physics and calculus, the differential equation determining the curve function is derived. The equation and initial conditions are cast into a dimensionless form first for universality of the results. It is found that the curves are effected by only one dimensionless parameter which is the ratio of the tangential acceleration to the normal acceleration. For no tangential acceleration, the equation can be solved analytically yielding a circular arc solution as expected. For nonzero tangential acceleration, the function is complicated and no closed-form solutions exist for the differential equation. The equation is solved numerically for various acceleration ratios. Discussions for applications to highway exits are given.
Stability of patterns on thin curved surfaces
NASA Astrophysics Data System (ADS)
Nampoothiri, Sankaran
2016-08-01
We consider reaction-diffusion equations on a thin curved surface and obtain a set of effective reaction-diffusion (R-D) equations to O (ɛ2) , where ɛ is the surface thickness. We observe that the R-D systems on these curved surfaces can have space-dependent reaction kinetics. Further, we use linear stability analysis to study the Schnakenberg model on spherical and cylindrical geometries. The dependence of the steady state on the thickness is determined for both cases, and we find that a change in the thickness can stabilize the unstable modes, and vice versa. The combined effect of thickness and curvature can play an important role in the rearrangement of spatial patterns on thin curved surfaces.
NASA Astrophysics Data System (ADS)
Fatah, Abd.; Rozaimi
2015-12-01
In this paper, we will discuss about the construction of fuzzy tuning B-spline curve based on fuzzy set theory. The concept of fuzzy tuning in designing this B-spline curve is based on the uncertain knots values which has to be defined first and then the result will be blended together with B-spline function which exists in users presumption in deciding the best knots value of tuning. Therefore, fuzzy set theory especially fuzzy number concepts are used to define the uncertain knots values and then it will be become fuzzy knots values. The Result by using different values of fuzzy knots for constructing a fuzzy tuning of B-spline curves will be illustrated.
Stability of patterns on thin curved surfaces.
Nampoothiri, Sankaran
2016-08-01
We consider reaction-diffusion equations on a thin curved surface and obtain a set of effective reaction-diffusion (R-D) equations to O(ε^{2}), where ε is the surface thickness. We observe that the R-D systems on these curved surfaces can have space-dependent reaction kinetics. Further, we use linear stability analysis to study the Schnakenberg model on spherical and cylindrical geometries. The dependence of the steady state on the thickness is determined for both cases, and we find that a change in the thickness can stabilize the unstable modes, and vice versa. The combined effect of thickness and curvature can play an important role in the rearrangement of spatial patterns on thin curved surfaces. PMID:27627331
Plasticity and rectangularity in survival curves
Weon, Byung Mook; Je, Jung Ho
2011-01-01
Living systems inevitably undergo a progressive deterioration of physiological function with age and an increase of vulnerability to disease and death. To maintain health and survival, living systems should optimize survival strategies with adaptive interactions among molecules, cells, organs, individuals, and environments, which arises plasticity in survival curves of living systems. In general, survival dynamics in a population is mathematically depicted by a survival rate, which monotonically changes from 1 to 0 with age. It would be then useful to find an adequate function to describe complicated survival dynamics. Here we describe a flexible survival function, derived from the stretched exponential function by adopting an age-dependent shaping exponent. We note that the exponent is associated with the fractal-like scaling in cumulative mortality rate. The survival function well depicts general features in survival curves; healthy populations exhibit plasticity and evolve towards rectangular-like survival curves, as examples in humans or laboratory animals. PMID:22355622
The genus curve of the Abell clusters
NASA Technical Reports Server (NTRS)
Rhoads, James E.; Gott, J. Richard, III; Postman, Marc
1994-01-01
We study the topology of large-scale structure through a genus curve measurement of the recent Abell catalog redshift survey of Postman, Huchra, and Geller (1992). The structure is found to be spongelike near median density and to exhibit isolated superclusters and voids at high and low densities, respectively. The genus curve shows a slight shift toward 'meatball' topology, but remains consistent with the hypothesis of Gaussian random phase initial conditions. The amplitude of the genus curve corresponds to a power-law spectrum with index n = 0.21(sub -0.47 sup +0.43) on scales of 48/h Mpc or to a cold dark matter power spectrum with omega h = 0.36(sub -0.17 sup +0.46).
Experimental simulation of closed timelike curves.
Ringbauer, Martin; Broome, Matthew A; Myers, Casey R; White, Andrew G; Ralph, Timothy C
2014-01-01
Closed timelike curves are among the most controversial features of modern physics. As legitimate solutions to Einstein's field equations, they allow for time travel, which instinctively seems paradoxical. However, in the quantum regime these paradoxes can be resolved, leaving closed timelike curves consistent with relativity. The study of these systems therefore provides valuable insight into nonlinearities and the emergence of causal structures in quantum mechanics--essential for any formulation of a quantum theory of gravity. Here we experimentally simulate the nonlinear behaviour of a qubit interacting unitarily with an older version of itself, addressing some of the fascinating effects that arise in systems traversing a closed timelike curve. These include perfect discrimination of non-orthogonal states and, most intriguingly, the ability to distinguish nominally equivalent ways of preparing pure quantum states. Finally, we examine the dependence of these effects on the initial qubit state, the form of the unitary interaction and the influence of decoherence. PMID:24942489
Smoothing Rotation Curves in Spiral Galaxies
NASA Astrophysics Data System (ADS)
Berrier, Joel C.; Sellwood, Jerry
2014-05-01
We present evidence that spiral activity is responsible for the creation of featureless rotation curves. We examine a variety of simulations of disk galaxies beginning in equilibrium and allow them to evolve while adding particles in annuli to the hot disk using a variety of rules. Two unstable spiral modes develop when this new material forms a ridge-like feature in the surface density profile of the disk. The extra material is redistributed radially by the spiral activity, and the associated angular momentum changes remove more particles from the ridge than are added to it. This process eventually removes the density feature from the galaxy and creates a locally flat rotation curve. We argue that the lack of a feature when transitioning from disk to halo dominance in the rotation curves of disk galaxies, the so called ``disk-halo conspiracy'', could also be accounted for by this mechanism.
Diffusion-limited aggregation on curved surfaces
NASA Astrophysics Data System (ADS)
Choi, J.; Crowdy, D.; Bazant, M. Z.
2010-08-01
We develop a general theory of transport-limited aggregation phenomena occurring on curved surfaces, based on stochastic iterated conformal maps and conformal projections to the complex plane. To illustrate the theory, we use stereographic projections to simulate diffusion-limited aggregation (DLA) on surfaces of constant Gaussian curvature, including the sphere (K>0) and the pseudo-sphere (K<0), which approximate "bumps" and "saddles" in smooth surfaces, respectively. Although the curvature affects the global morphology of the aggregates, the fractal dimension (in the curved metric) is remarkably insensitive to curvature, as long as the particle size is much smaller than the radius of curvature. We conjecture that all aggregates grown by conformally invariant transport on curved surfaces have the same fractal dimension as DLA in the plane. Our simulations suggest, however, that the multifractal dimensions increase from hyperbolic (K<0) to elliptic (K>0) geometry, which we attribute to curvature-dependent screening of tip branching.
The learning curves of competitive programming
NASA Astrophysics Data System (ADS)
Garcia, Jose R.; Aguirre, Vanessa E.
2014-10-01
Universities around the world have implemented competitive programming as an approach to teach computer science courses. They have empirically validated this approach as a successful pedagogical tool. However, there are no conclusive results that describe the degree in which competitive programming affects the learning process of the students. In this paper, we report on the learning curves obtained from analyzing ten years of TopCoder algorithm competitions. We discuss on how these learning curves apply to university courses and can help us explain the influence of competitive programming in a class.
The galactic rotation curve from OH observations
Kolesnik, I.G.; Yurevich, L.V.
1985-11-01
This paper shows that the galactic rotation curve is determined up to galactocentric distances of 16 kpc from the relation between the parameters of the absorption lines for molecular OH clouds and the distance to them. Results are given separately for the two galactocentric guadrants which border each along the line from the center of the Galaxy to the Sun. The rotation curve so obtained repeats the kinematical laws established from observed parameters of the hydroxyl absorption lines in order to determine the distances to the molecular clouds in the Galaxy. The distance of the Sun from the center of the Galaxy is estimated.
Multivariate curve resolution in liquid chromatography
Osten, D.W.; Kowalski, B.R.
1983-12-01
Self-modeling curve resolution has been shown to allow resolution of two co-eluting chromatographic peaks without requiring any assumption of an underlying peak shape. The subsequent problem of quantitation of these co-eluting peaks is limited by both the chromatographic resolution (separation in time and difference in elution profile) and by the degree of spectral uniqueness. An experimental system of two water-soluble vitamins has been used to examine the effects of varying chromatographic resolution on the quantitative accuracy of the curve resolution method.
Stellar Rotation Curves of Starbursting Dwarf Galaxies
NASA Astrophysics Data System (ADS)
van Zee, Liese; Skillman, Evan D.; Salzer, John J.
2001-02-01
A year ago, we successfully completed a pilot project to obtain stellar rotation curves of starbursting dwarf galaxies. These observations provided the first spatially resolved stellar rotation curves of gas-rich dwarf galaxies. We now propose to expand our sample (by a factor of 2) by observing 4 additional dwarf galaxies with the CTIO 4m. The fundamental question to be addressed is whether the gas and stars are kinematically coupled in these small galaxies. These observations will place the first kinematic constraints on evolutionary models for dwarf galaxies.
Dynamic Curving Simulation of Tilting Train
NASA Astrophysics Data System (ADS)
Zeng, Jing; Luo, Ren
The application of carbody tilting technology is the most efficient way to raise train speed during curve negotiations. This paper mainly deals with the dynamic performance simulation of the tilting train. Through the establishment of the nonlinear mathematical model for the titling train electromechanical coupled system, the carbody tilting control law, bogie radial steering mechanism, and titling train curving performance are investigated. The effect of time delay caused by the sensing and control system on the tilting performance of the train is analyzed, and the compensation methods for the time delay effect are studied.
Dynamic critical curve of a synthetic antiferromagnet
NASA Astrophysics Data System (ADS)
Pham, Huy; Cimpoesu, Dorin; Plamadǎ, Andrei-Valentin; Stancu, Alexandru; Spinu, Leonard
2009-11-01
In this letter, a dynamic generalization of static critical curves (sCCs) for synthetic antiferromagnet (SAF) structures is presented, analyzing the magnetization switching of SAF elements subjected to pulsed magnetic fields. The dependence of dynamic critical curves (dCCs) on field pulse's shape and length, on damping, and on magnetostatic coupling is investigated. Comparing sCCs, which are currently used for studying the switching in toggle magnetic random access memories, with dCCs, it is shown that a consistent switching can be achieved only under specific conditions that take into account the dynamics of the systems. The study relies on the Landau-Lifshitz-Gilbert equation.
Chiral mass-gap in curved space.
Flachi, Antonino; Fukushima, Kenji
2014-08-29
We discuss a new type of QCD phenomenon induced in curved space. In the QCD vacuum, a mass-gap of Dirac fermions is attributed to the spontaneous breaking of chiral symmetry. If the curvature is positive large, the chiral condensate melts but a chiral invariant mass-gap can still remain, which we name the chiral gap effect in curved space. This leads to decoupling of quark deconfinement which implies a view of black holes surrounded by a first-order QCD phase transition. PMID:25215970
How current loops and solenoids curve spacetime
NASA Astrophysics Data System (ADS)
Füzfa, André
2016-01-01
The curved spacetime around current loops and solenoids carrying arbitrarily large steady electric currents is obtained from the numerical resolution of the coupled Einstein-Maxwell equations in cylindrical symmetry. The artificial gravitational field associated to the generation of a magnetic field produces gravitational redshift of photons and deviation of light. Null geodesics in the curved spacetime of current loops and solenoids are also presented. We finally propose an experimental setup achievable with current technology of superconducting coils, that produces a phase shift of light of the same order of magnitude as astrophysical signals in ground-based gravitational wave observatories.
Making Curved Frequency-Selective Microwave Reflectors
NASA Technical Reports Server (NTRS)
Hickey, Gregory S.; Wu, Te-Kao
1995-01-01
Prototype curved lightweight dichroic microwave reflectors designed to be highly reflective in X and K(suba) frequency bands and highly transmissive in K(subu) and S bands. Conductive grid elements formed photolithographically on curved reflector surfaces. Intended for use as subreflectors of main paraboloidal antenna reflector to enable simultaneous operation in both prime-focus configuration in K(subu) and S bands and Cassegrain configuration in X and K(suba) bands. Basic concepts of reflectors described in "Frequency-Selective Microwave Reflectors" (NPO-18701). "Double Square-Loop Dichroic Microwave Reflector" (NPO-18676), "Triband Circular-Loop Dichroic Microwave Reflector" (NPO-18714), and "Improved Dichroic Microwave Reflector" (NPO-18664).
Linking the Production Possibilities Curve, the Supply Curve, and the Competitive Norm.
ERIC Educational Resources Information Center
Kosicki, George
1991-01-01
Recommends that economics instruction begin a synthesizing process early by connecting discussion of the production possibilities curve and the supply curve. Suggests that linking the two is logical for conveying integrated economic thinking to beginning students. Argues that such a link makes it easier to discuss the competitive norm. (DK)
Preliminary Investigation of Curved Liner Sample in the NASA LaRC Curved Duct Test Rig
NASA Technical Reports Server (NTRS)
Gerhold, Carl H.; Jones, Michael G.; Brown, Martha C.
2007-01-01
This viewgraph presentation reviews the preliminary investigation of the curved liner sample in the NASA LaRC Curved Duct Test Rig (CDTR). It reviews the purpose of the Curved Duct Test Rig. Its purpose is to develop capability to investigate acoustic and aerodynamic properties in ducts. It has several features to accomplish that purpose: (1) Large scale (2) Flow rate to M = 0.275 (3) Higher order mode control (4) Curved flow path (5) Adaptable test section (6) Flexible test configurations. The liner has minimal effect on turbulence or boundary layer growth in duct. The curved duct sample attenuation is affected by mode scattering. In conclusion, the CDTR is valid tool for aerodynamic and acoustic evaluation of duct treatment
Double-mass curves; with a section fitting curves to cyclic data
Searcy, James K.; Hardison, Clayton H.; Langein, Walter B.
1960-01-01
The double.-mass curve is used to check the consistency of many kinds of hydrologic data by comparing data for a single station with that of a pattern composed of the data from several other stations in the area The double-mass curve can be used to adjust inconsistent precipitation data. The graph of the cumulative data of one variable versus the cumulative data of a related variable is a straight line so long as the relation between the variables is a fixed ratio. Breaks in the double-mass curve of such variables are caused by changes in the relation between the variables. These changes may be due to changes in the method of data collection or to physical changes that affect the relation. Applications of the double-mass curve to precipitation, streamflow, and sediment data, and to precipitation-runoff relations are described. A statistical test for significance of an apparent break in the slope of the double-mass curve is described by an example. Poor correlation between the variables can prevent detection of inconsistencies in a record, but an increase in the length of record tends to offset the effect of poor correlation. The residual-mass curve, which is a modification of the double-mass curve, magnifies imperceptible breaks in the double-mass curve for detailed study. Of the several methods of fitting a smooth curve to cyclic or periodic data, the moving-arc method and the double-integration method deserve greater use in hydrology. Both methods are described in this manual. The moving-arc method has general applicability, and the double integration method is useful in fitting a curve to cycles of sinusoidal form.
Pleats in crystals on curved surfaces.
Irvine, William T M; Vitelli, Vincenzo; Chaikin, Paul M
2010-12-16
Hexagons can easily tile a flat surface, but not a curved one. Introducing heptagons and pentagons (defects with topological charge) makes it easier to tile curved surfaces; for example, soccer balls based on the geodesic domes of Buckminster Fuller have exactly 12 pentagons (positive charges). Interacting particles that invariably form hexagonal crystals on a plane exhibit fascinating scarred defect patterns on a sphere. Here we show that, for more general curved surfaces, curvature may be relaxed by pleats: uncharged lines of dislocations (topological dipoles) that vanish on the surface and play the same role as fabric pleats. We experimentally investigate crystal order on surfaces with spatially varying positive and negative curvature. On cylindrical capillary bridges, stretched to produce negative curvature, we observe a sequence of transitions-consistent with our energetic calculations-from no defects to isolated dislocations, which subsequently proliferate and organize into pleats; finally, scars and isolated heptagons (previously unseen) appear. This fine control of crystal order with curvature will enable explorations of general theories of defects in curved spaces. From a practical viewpoint, it may be possible to engineer structures with curvature (such as waisted nanotubes and vaulted architecture) and to develop novel methods for soft lithography and directed self-assembly. PMID:21164482
Item Characteristic Curves: A New Theoretical Approach.
ERIC Educational Resources Information Center
Garcia-Perez, Miguel A.; Frary, Robert B.
A new approach to the development of the item characteristic curve (ICC), which expresses the functional relationship between the level of performance on a given task and an independent variable that is relevant to the task, is presented. The approach focuses on knowledge states, decision processes, and other circumstances underlying responses to…
A Class Inquiry into Newton's Cooling Curve
ERIC Educational Resources Information Center
Bartholow, Martin
2007-01-01
Newton's cooling curve was chosen for the four-part laboratory inquiry into conditions affecting temperature change. The relationship between time and temperature is not foreseen by the average high school student before the first session. However, during several activities students examine the classic relationship, T = A exp[superscript -Ct] + B…
Light extraction block with curved surface
Levermore, Peter; Krall, Emory; Silvernail, Jeffrey; Rajan, Kamala; Brown, Julia J.
2016-03-22
Light extraction blocks, and OLED lighting panels using light extraction blocks, are described, in which the light extraction blocks include various curved shapes that provide improved light extraction properties compared to parallel emissive surface, and a thinner form factor and better light extraction than a hemisphere. Lighting systems described herein may include a light source with an OLED panel. A light extraction block with a three-dimensional light emitting surface may be optically coupled to the light source. The three-dimensional light emitting surface of the block may includes a substantially curved surface, with further characteristics related to the curvature of the surface at given points. A first radius of curvature corresponding to a maximum principal curvature k.sub.1 at a point p on the substantially curved surface may be greater than a maximum height of the light extraction block. A maximum height of the light extraction block may be less than 50% of a maximum width of the light extraction block. Surfaces with cross sections made up of line segments and inflection points may also be fit to approximated curves for calculating the radius of curvature.
The wavelength dependence of Triton's light curve
NASA Technical Reports Server (NTRS)
Hillier, J.; Veverka, J.; Helfenstein, P.; Mcewen, A.
1991-01-01
Using Voyager observations, it is demonstrated that Triton's orbital light curve is strongly wavelength-dependent, a characteristic which readily explains some of the apparent discrepancies among pre-Voyager telescopic measurements. Specifically, a light curve amplitude (peak to peak) is found that decreases systematically with increasing wavelength from about 0.08 magnitude (peak to peak) near 200 nm to less than 0.02 magnitude near 1000 nm. Peak brightness occurs near 90 deg orbital longitude (leading hemisphere). The brightness variation across this hemisphere is close to sinusoidal; the variation across the darker hemisphere is more complex. The decrease in light curve amplitude with increasing wavelength appears to be due to a decrease in contrast among surface markings, rather than to atmospheric obscuration. The model also explains the observed decrease in the amplitude of Triton's light curve at visible wavelengths over the past decade, a decrease related to the current migration of the subsolar latitude toward the south pole; it is predicted that this trend will continue into the 1990s.
Curve fitting of mixed-mode isopachics
NASA Astrophysics Data System (ADS)
Hebb, R. I.; Dulieu-Barton, J. M.; Worden, K.; Tatum, P.
2009-08-01
Recent work has focused on exploiting the observation that the stress-sum contours (isopachics), obtained from TSA, in the vicinity of the tip take the form of a simple curve - the cardioid. The analysis made use of the cardioid nature of the isopachics by deriving expressions for the SIFs in terms of the cardioid area and the positions of certain tangents to the curve. Both Genetic Algorithms (GAs) and Differential Evolution (DE) have also proved successful for parameter estimation, but some of the curve-fits indicated that the cardioid form was inappropriate for the base model, particularly for mixed-mode cracks. The effect of crack-tip interaction has been explored and shows this has a small effect on the cardioid form. New, higher resolution infra-red detectors have become available since the original data was collected, so the object of the current paper is to use new techniques to extract the cardioid form and use a GA to perform the curve fitting.
Demonstrating e Using Areas under Curves
ERIC Educational Resources Information Center
Plant, Allison
2009-01-01
The number "e" is one of those fascinating numbers whose properties are of special interest to mathematicians. In this article, the author aims to provide a method of introducing a visual concept of the number "e". These ideas are suitable for secondary school and undergraduate tertiary students. The main concept involves areas under curves.…
How Skewed Is "The Bell Curve"?
ERIC Educational Resources Information Center
Haynes, Norris M.
Few books have generated as much controversy as the recently published "The Bell Curve: Intelligence and Class Structure in American Life." The tremendous polarization on the issue of the relationship between intelligence quotient (IQ) to race and social class, reinforced by the book, and the potential this book has for undermining social programs…
Is the Water Heating Curve as Described?
ERIC Educational Resources Information Center
Riveros, H. G.; Oliva, A. I.
2008-01-01
We analysed the heating curve of water which is described in textbooks. An experiment combined with some simple heat transfer calculations is discussed. The theoretical behaviour can be altered by changing the conditions under which the experiment is modelled. By identifying and controlling the different parameters involved during the heating…
Nonlinear Growth Curves in Developmental Research
ERIC Educational Resources Information Center
Grimm, Kevin J.; Ram, Nilam; Hamagami, Fumiaki
2011-01-01
Developmentalists are often interested in understanding change processes, and growth models are the most common analytic tool for examining such processes. Nonlinear growth curves are especially valuable to developmentalists because the defining characteristics of the growth process such as initial levels, rates of change during growth spurts, and…
Measuring Systematic Error with Curve Fits
ERIC Educational Resources Information Center
Rupright, Mark E.
2011-01-01
Systematic errors are often unavoidable in the introductory physics laboratory. As has been demonstrated in many papers in this journal, such errors can present a fundamental problem for data analysis, particularly when comparing the data to a given model. In this paper I give three examples in which my students use popular curve-fitting software…
"The Bell Curve" on Separated Twins.
ERIC Educational Resources Information Center
Fancher, Raymond E.
1995-01-01
"The Bell Curve" declares that studies of separated identical twins--the "purest" of "direct" methods for estimating IQ heritability--indicate a value of +.75-+.80. But, the main study cited suggests a heritability of "two-thirds" for the middle class, and Herrnstein and Murray neglect to mention numerous complicating factors in twin studies that…
Mass Distributions Implying Flat Galactic Rotation Curves
ERIC Educational Resources Information Center
Keeports, David
2010-01-01
The rotational speeds of stars in the disc of a spiral galaxy are virtually independent of the distances of the stars from the centre of the galaxy. In common parlance, the stellar speed versus distance plot known as a galactic rotation curve is by observation typically nearly flat. This observation provides strong evidence that most galactic…
Jet flow on ribbed curved surfaces
NASA Astrophysics Data System (ADS)
Lashkov, Iu. A.; Sokolova, I. N.; Shumilkina, E. A.
1992-02-01
The objective of the study was to investigate the possibility of using microribbing to reduce turbulent friction in Coanda flows over curved surfaces. It is shown that ribs make it possible to reduce the effect of a jet impinging on an obstacle and to prevent the Coanda effect when jet attachment is undesirable. The optimal rib parameters are determined.
Residual Structures in Latent Growth Curve Modeling
ERIC Educational Resources Information Center
Grimm, Kevin J.; Widaman, Keith F.
2010-01-01
Several alternatives are available for specifying the residual structure in latent growth curve modeling. Two specifications involve uncorrelated residuals and represent the most commonly used residual structures. The first, building on repeated measures analysis of variance and common specifications in multilevel models, forces residual variances…
Sediment transport in a curved channel
Altunin, V.S.; Larinova, L.V.; Martinkus, A.T.; Novikova, N.M.
1987-11-01
The authors construct mathematical and experimental flow models to describe the hydrodynamic behavior of sediments eroding into hydroelectric plant waterways for purposes of arriving at sediment reclamation scenarios as well as optimizing waterway design parameters for the minimization of erosion. The models simulate both straight and curved waterways and also allow the determination of the cross-sectional design.
Updated Hubbert curves analyze world oil supply
Ivanhoe, L.F.
1996-11-01
The question is not whether, but when, world crude oil production will start to decline, ushering in the permanent oil shock era. While global information for predicting this event is not so straightforward as the data M. King Hubbert used in creating his famous Hubbert Curve that predicted the US (Lower 48 states, or US/48) 1970 oil production peak, there are strong indications that most of the world`s large exploration targets have now been found. Meanwhile, the earth`s population is exploding along with the oil needs of Asia`s developing nations. This article reviews Hubbert`s original analyses on oil discovery and production curves for the US/48 and projects his proven methodology onto global oil discoveries and production as of 1992. The world`s oil discovery curve peaked in 1962, and thence declined, as a Hubbert Curve predicts. However, global production was restricted after the 1973 Arab oil embargo. Otherwise, world production would have peaked in the mid-1990s. Two graphs show alternate versions of future global oil production.
The Ultimate Spitzer Phase Curve Survey
NASA Astrophysics Data System (ADS)
Stevenson, Kevin; Bean, Jacob; Deming, Drake; Desert, Jean-Michel; Feng, Y. Katherina; Fortney, Jonathan; Kataria, Tiffany; Kempton, Eliza; Lewis, Nikole; Line, Michael; Morley, Caroline; Rauscher, Emily; Showman, Adam
2016-08-01
Exoplanet phase curves are sure to be one of the main enduring legacies of Spitzer. They provide a wealth of information about exoplanet atmospheres, including longitudinal constraints on atmospheric composition, thermal structure, and energy transport, that will continue to open new doors of scientific inquiry and propel future investigations for years to come. The measured heat redistribution efficiency (or ability to transport energy from a planet's highly-irradiated dayside to its eternally-dark nightside) shows considerable variation between exoplanets. Theoretical models predict a correlation between heat redistribution efficiency and planet temperature; however, the latest results are inconsistent with current predictions. Instead, a new potential trend is emerging, one that connects heat redistribution efficiency with planet rotation rate. We will test this hypothesis by performing Spitzer phase curve observations of seven exoplanets with physical properties that span the parameter space. We have identified high-contrast targets with short orbital periods around bright host stars to ensure the observations reveal robust phase curve results. Spitzer is uniquely suited for this program because we can achieve our primary goals using broadband photometry. Part of the phase curve legacy will be to combine our archived Spitzer data with transmission and dayside emission spectra from HST and JWST. Adding energy transport and cloud coverage constraints to the measured dayside abundances and thermal profiles will yield a fundamental understanding of these exoplanets' atmospheres that can be leveraged into new avenues of investigation.
Singular interactions supported by embedded curves
NASA Astrophysics Data System (ADS)
Tevfik Kaynak, Burak; Teoman Turgut, O.
2012-07-01
In this work, singular interactions supported by embedded curves on Riemannian manifolds are discussed from a more direct and physical perspective, via the heat kernel approach. We show that the renormalized problem is well defined, the ground state is finite and the corresponding wavefunction is positive. The renormalization group invariance of the model is also discussed. Dedicated to the memory of Professor Yavuz Nutku.
ERIC Educational Resources Information Center
Wangler, David G.
1995-01-01
Calls for careful but unemotional criticism of "The Bell Curve." Notes that: three chapters that deal with the IQ-race relationship have received most critical attention; genetically based racial categories do not exist; disadvantaged minority-group students have achieved success in Catholic schools with high expectations of students; and social…
Fermat's Technique of Finding Areas under Curves
ERIC Educational Resources Information Center
Staples, Ed
2004-01-01
Perhaps next time teachers head towards the fundamental theorem of calculus in their classroom, they may wish to consider Fermat's technique of finding expressions for areas under curves, beautifully outlined in Boyer's History of Mathematics. Pierre de Fermat (1601-1665) developed some important results in the journey toward the discovery of the…
Liquefaction probability curves for surficial geologic deposits
Holzer, Thomas L.; Noce, Thomas E.; Bennett, Michael J.
2011-01-01
Liquefaction probability curves that predict the probability of surface manifestations of earthquake-induced liquefaction are developed for 14 different types of surficial geologic units. The units consist of alluvial fan, beach ridge, river delta topset and foreset beds, eolian dune, point bar, flood basin, natural river and alluvial fan levees, abandoned river channel, deep-water lake, lagoonal, sandy artificial fill, and valley train deposits. Probability is conditioned on earthquake magnitude and peak ground acceleration. Curves are developed for water table depths of 1.5 and 5.0 m. Probabilities are derived from complementary cumulative frequency distributions of the liquefaction potential index (LPI) that were computed from 927 cone penetration tests. For natural deposits with a water table at 1.5 m and subjected to a M7.5 earthquake with peak ground acceleration (PGA) = 0.25g, probabilities range from 0.5 for beach ridge, point bar, and deltaic deposits. The curves also were used to assign ranges of liquefaction probabilities to the susceptibility categories proposed previously for different geologic deposits. For the earthquake described here, probabilities for susceptibility categories have ranges of 0–0.08 for low, 0.09–0.30 for moderate, 0.31–0.62 for high, and 0.63–1.00 for very high. Retrospective predictions of liquefaction during historical earthquakes based on the curves compare favorably to observations.
Nonadiabatic transitions at potential curve crossings
Nakamura, Hiroki; Zhu, Chaoyuan
1996-12-31
Recently, the Landau-Zener-Stueckelberg problems have been completely solved in a form convenient for various applications. A summary of the results will be reported. Other related subjects such as multi-level curve crossing and conical intersection problems will also be briefly touched upon.
Serial Position Curves in Free Recall
ERIC Educational Resources Information Center
Laming, Donald
2010-01-01
The scenario for free recall set out in Laming (2009) is developed to provide models for the serial position curves from 5 selected sets of data, for final free recall, and for multitrial free recall. The 5 sets of data reflect the effects of rate of presentation, length of list, delay of recall, and suppression of rehearsal. Each model…
"The Bell Curve": Review of Reviews.
ERIC Educational Resources Information Center
Parker, Franklin; Parker, Betty J.
This paper reviews the book "The Bell Curve" by Harvard psychologist Richard J. Herrnstein and political scientist Charles Alan Murray. The paper asserts as the book's main points and implications: (1) one's socioeconomic place in life is now determined by IQ rather than family wealth and influence; (2) ruling white elites, who have benefited from…
Modeling and Fitting Exoplanet Transit Light Curves
NASA Astrophysics Data System (ADS)
Millholland, Sarah; Ruch, G. T.
2013-01-01
We present a numerical model along with an original fitting routine for the analysis of transiting extra-solar planet light curves. Our light curve model is unique in several ways from other available transit models, such as the analytic eclipse formulae of Mandel & Agol (2002) and Giménez (2006), the modified Eclipsing Binary Orbit Program (EBOP) model implemented in Southworth’s JKTEBOP code (Popper & Etzel 1981; Southworth et al. 2004), or the transit model developed as a part of the EXOFAST fitting suite (Eastman et al. in prep.). Our model employs Keplerian orbital dynamics about the system’s center of mass to properly account for stellar wobble and orbital eccentricity, uses a unique analytic solution derived from Kepler’s Second Law to calculate the projected distance between the centers of the star and planet, and calculates the effect of limb darkening using a simple technique that is different from the commonly used eclipse formulae. We have also devised a unique Monte Carlo style optimization routine for fitting the light curve model to observed transits. We demonstrate that, while the effect of stellar wobble on transit light curves is generally small, it becomes significant as the planet to stellar mass ratio increases and the semi-major axes of the orbits decrease. We also illustrate the appreciable effects of orbital ellipticity on the light curve and the necessity of accounting for its impacts for accurate modeling. We show that our simple limb darkening calculations are as accurate as the analytic equations of Mandel & Agol (2002). Although our Monte Carlo fitting algorithm is not as mathematically rigorous as the Markov Chain Monte Carlo based algorithms most often used to determine exoplanetary system parameters, we show that it is straightforward and returns reliable results. Finally, we show that analyses performed with our model and optimization routine compare favorably with exoplanet characterizations published by groups such as the
Trend analyses with river sediment rating curves
Warrick, Jonathan A.
2015-01-01
Sediment rating curves, which are fitted relationships between river discharge (Q) and suspended-sediment concentration (C), are commonly used to assess patterns and trends in river water quality. In many of these studies it is assumed that rating curves have a power-law form (i.e., C = aQb, where a and b are fitted parameters). Two fundamental questions about the utility of these techniques are assessed in this paper: (i) How well to the parameters, a and b, characterize trends in the data? (ii) Are trends in rating curves diagnostic of changes to river water or sediment discharge? As noted in previous research, the offset parameter, a, is not an independent variable for most rivers, but rather strongly dependent on b and Q. Here it is shown that a is a poor metric for trends in the vertical offset of a rating curve, and a new parameter, â, as determined by the discharge-normalized power function [C = â (Q/QGM)b], where QGM is the geometric mean of the Q values sampled, provides a better characterization of trends. However, these techniques must be applied carefully, because curvature in the relationship between log(Q) and log(C), which exists for many rivers, can produce false trends in â and b. Also, it is shown that trends in â and b are not uniquely diagnostic of river water or sediment supply conditions. For example, an increase in â can be caused by an increase in sediment supply, a decrease in water supply, or a combination of these conditions. Large changes in water and sediment supplies can occur without any change in the parameters, â and b. Thus, trend analyses using sediment rating curves must include additional assessments of the time-dependent rates and trends of river water, sediment concentrations, and sediment discharge.
Curved bones: An adaptation to habitual loading.
Milne, Nick
2016-10-21
Why are long bones curved? It has long been considered a paradox that many long bones supporting mammalian bodies are curved, since this curvature results in the bone undergoing greater bending, with higher strains and so greater fracture risk under load. This study develops a theoretical model wherein the curvature is a response to bending strains imposed by the requirements of locomotion. In particular the radioulna of obligate quadrupeds is a lever operated by the triceps muscle, and the bending strains induced by the triceps muscle counter the bending resulting from longitudinal loads acting on the curved bone. Indeed the theoretical model reverses this logic and suggests that the curvature is itself a response to the predictable bending strains induced by the triceps muscle. This, in turn, results in anatomical arrangements of bone, muscle and tendon that create a simple physiological mechanism whereby the bone can resist the bending due to the action of triceps in supporting and moving the body. The model is illustrated by contrasting the behaviour of a finite element model of a llama radioulna to that of a straightened version of the same bone. The results show that longitudinal and flexor muscle forces produce bending strains that effectively counter strains due to the pull of the triceps muscle in the curved but not in the straightened model. It is concluded that the curvature of these and other curved bones adds resilience to the skeleton by acting as pre-stressed beams or strainable pre-buckled struts. It is also proposed that the cranial bending strains that result from triceps, acting on the lever that is the radioulna, can explain the development of the curvature of such bones. PMID:27444401
A "chaos" of Phanerozoic eustatic curves
NASA Astrophysics Data System (ADS)
Ruban, Dmitry A.
2016-04-01
The knowledge of eustasy has changed during the past two decades. Although there is not any single global sea-level curve for the entire Phanerozoic, new curves have been proposed for all periods. For some geological time intervals, there are two and more alternative reconstructions, from which it is difficult to choose. A significant problem is the available eustatic curves are justified along different geological time scales (sometimes without proper explanations), which permits to correlate eustatic events with the possible error of 1-3 Ma. This degree of error permits to judge about only substage- or stage-order global sea-level changes. Close attention to two geological time slices, namely the late Cambrian (Epoch 3‒Furongian) and the Late Cretaceous, implies that only a few eustatic events (6 events in the case of the late Cambrian and 9 events in the case of the Late Cretaceous) appear on all available alternative curves for these periods, and different (even opposite) trends of eustatic fluctuations are shown on these curves. This reveals significant uncertainty in our knowledge of eustasy that restricts our ability to decipher factors responsible for regional transgressions and regressions and relative sea-level changes. A big problem is also inadequate awareness of the geological research community of the new eustatic developments. Generally, the situation with the development and the use of the Phanerozoic eustatic reconstructions seems to be "chaotic". The example of the shoreline shifts in Northern Africa during the Late Cretaceous demonstrates the far-going consequences of this situation. The practical recommendations to avoid this "chaos" are proposed. Particularly, these claim for good awareness of all eustatic developments, their critical discussion, and clear explanation of the employed geological time scale.
Synthesis of novel sulfosalt materials with curved crystalline habits
NASA Astrophysics Data System (ADS)
Crawford, Guy Moore
Minerals and man-made materials with circular crystalline habit are very rare. A group of the complex iron-containing sulfosalt minerals exhibit a non-commensurate layered crystalline structure and are found with curved crystals. Cylindrite, named because of its cylindrical crystal habit, is the most easily recognized member of the group. The other members of the family, franckeite, incaite and potosiite, have similar compositions and are all lamellar. The two incommensurate interpenetrating sublattices have different but definite structures. One sublattice is PbS-type pseudotetragonal and the other SnS 2-type pseudohexagonal. Iron is found in both sublattices. The detailed crystal structures of these minerals remains unsolved. With the exception of a few phase studies, little is known about the chemistry of the minerals or the mechanism that prompts the formation of these misfit-layered materials. As sulfides, these minerals are of interest for their potential electronic and magnetic applications. A series of synthesis reactions were carried out to examine the effects on the properties and structures of the sulfosalts that are induced by the substitutions into the crystal lattice. Other transition metals were substituted in the place of iron in the incommensurate minerals, and selenium and tellurium replaced sulfur in cylindrite. The structure and properties were evaluated by environmental scanning electron microscopy, X-ray diffraction and differential thermal analysis. Curved and lamellar features were observed in several phases of the synthetic substitutional products. No correlations were immediately evident relating the composition to the propensity to form curved features.* *This dissertation is multimedia (contains text and other applications not available in printed format). The CD requires the following system application: Microsoft Office.
Positional glow curve simulation for thermoluminescent detector (TLD) system design
NASA Astrophysics Data System (ADS)
Branch, C. J.; Kearfott, K. J.
1999-02-01
Multi- and thin element dosimeters, variable heating rate schemes, and glow-curve analysis have been employed to improve environmental and personnel dosimetry using thermoluminescent detectors (TLDs). Detailed analysis of the effects of errors and optimization of techniques would be highly desirable. However, an understanding of the relationship between TL light production, light attenuation, and precise heating schemes is made difficult because of experimental challenges involved in measuring positional TL light production and temperature variations as a function of time. This work reports the development of a general-purpose computer code, thermoluminescent detector simulator, TLD-SIM, to simulate the heating of any TLD type using a variety of conventional and experimental heating methods including pulsed focused or unfocused lasers with Gaussian or uniform cross sections, planchet, hot gas, hot finger, optical, infrared, or electrical heating. TLD-SIM has been used to study the impact on the TL light production of varying the input parameters which include: detector composition, heat capacity, heat conductivity, physical size, and density; trapped electron density, the frequency factor of oscillation of electrons in the traps, and trap-conduction band potential energy difference; heating scheme source terms and heat transfer boundary conditions; and TL light scatter and attenuation coefficients. Temperature profiles and glow curves as a function of position time, as well as the corresponding temporally and/or spatially integrated glow values, may be plotted while varying any of the input parameters. Examples illustrating TLD system functions, including glow curve variability, will be presented. The flexible capabilities of TLD-SIM promises to enable improved TLD system design.
Transport of airborne particles in straight and curved microchannels
NASA Astrophysics Data System (ADS)
Schaap, Allison; Chu, Winnie C.; Stoeber, Boris
2012-08-01
The measurement of airborne particles is important for environmental and exposure monitoring. Microfluidic technologies present potential advantages for aerosol monitoring but have been applied very little to the handling of airborne particles. In this paper, we examine the flow focusing and cross-streamline diffusion of aerosols in straight microchannels, and the size-based lateral displacement of aerosols caused by centrifugal forces in a curved channel. We present calculations, simulations, and experimental results verifying the models: measurements of the focusing and diffusion of 0.2 μm and 0.75 μm particles in straight channels and of the size-dependent lateral displacement of particles between 0.2 μm and 2 μm in curved channels are demonstrated and shown to match well with the simulations. We observe lateral dispersion of the particles: particles closer to the top and bottom wall of the channel experience less lateral displacement than particles near the center due to the flow velocity distribution across the channel cross section. These results confirm that the microchannel techniques presented are a viable method for the size-based manipulation of airborne particles.
The impact of energy, transport, and trade on air pollution in China
Poon, J.P.H.; Casas, I.; He, C.F.
2006-09-15
A team of U.S.- and China-based geographers examines the relationship between China's economic development and its environment by modeling the effects of energy, transport, and trade on local air pollution emissions (sulfur dioxide and soot particulates) using the Environmental Kuznets model. Specifically, the latter model is investigated using spatial econometrics that take into account potential regional spillover effects from high-polluting neighbors. The analysis finds an inverted-U relationship for sulfur dioxide but a U-shaped curve for soot particulates. This suggests that soot particulates such as black carbon may pose a more serious environmental problem in China than sulfur dioxide.
Seebacher, Frank; Grigaltchik, Veronica S
2014-01-01
Performance curves of physiological rates are not fixed, and determining the extent to which thermal performance curves can change in response to environmental signals is essential to understand the effect of climate variability on populations. The aim of this study was to determine whether and how temperatures experienced during early embryonic development affect thermal performance curves of later life history stages in the frog Limnodynastes peronii. We tested the hypotheses that a) the embryonic environment affects mean trait values only; b) temperature at which performance of tadpoles is maximal shifts with egg incubation temperatures so that performance is maximised at the incubation temperatures, and c) incubation temperatures modulate the capacity for reversible acclimation in tadpoles. Growth rates were greater in warm (25°C) compared to cold (15°C) acclimated (6 weeks) tadpoles regardless of egg developmental temperatures (15°C or 25°C, representing seasonal means). The breadth of the performance curve of burst locomotor performance (measured at 10, 15, 20, 25, and 30°C, representing annual range) is greatest when egg developmental and acclimation temperatures coincide. The mode of the performance curves shifted with acclimation conditions and maximum performance was always at higher temperatures than acclimation conditions. Performance curves of glycolytic (lactate dehydrogenase activities) and mitochondrial (citrate synthase and cytochrome c oxidase) enzymes were modulated by interactions between egg incubation and acclimation temperatures. Lactate dehydrogenase activity paralleled patterns seen in burst locomotor performance, but oxygen consumption rates and mitochondrial enzyme activities did not mirror growth or locomotor performance. We show that embryonic developmental conditions can modulate performance curves of later life-history stages, thereby conferring flexibilty to respond to environmental conditions later in life. PMID:25181291
Analytical drafting curves provide exact equations for plotted data
NASA Technical Reports Server (NTRS)
Stewart, R. B.
1967-01-01
Analytical drafting curves provide explicit mathematical expressions for any numerical data that appears in the form of graphical plots. The curves each have a reference coordinate axis system indicated on the curve as well as the mathematical equation from which the curve was generated.
Surface family with a common involute asymptotic curve
NASA Astrophysics Data System (ADS)
Bayram, Ergi˙n; Bi˙li˙ci˙, Mustafa
2016-03-01
We construct a surface family possessing an involute of a given curve as an asymptotic curve. We express necessary and sufficient conditions for that curve with the above property. We also present natural results for such ruled surfaces. Finally, we illustrate the method with some examples, e.g. circles and helices as given curves.
49 CFR 213.59 - Elevation of curved track; runoff.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Elevation of curved track; runoff. 213.59 Section... track; runoff. (a) If a curve is elevated, the full elevation shall be provided throughout the curve, unless physical conditions do not permit. If elevation runoff occurs in a curve, the actual...
The pattern of secondary root formation in curving roots of Arabidopsis thaliana (L.) Heynh
NASA Technical Reports Server (NTRS)
Fortin, M. C.; Pierce, F. J.; Poff, K. L.
1989-01-01
A gravitational stimulus was used to induce the curvature of the main root of Arabidopsis thaliana. The number of secondary roots increased on the convex side and decreased on the concave side of any curved main root axes in comparison with straight roots used as the control. The same phenomenon was observed with the curved main roots of plants grown on a clinostat and of mutant plants exhibiting random root orientation. The data suggest that the pattern of lateral root formation is associated with curvature but is independent of the environmental stimuli used to induce curvature.
Curved butterfly bileaflet prosthetic cardiac valve
McQueen, David M.; Peskin, Charles S.
1991-06-25
An annular valve body having a central passageway for the flow of blood therethrough with two curved leaflets each of which is pivotally supported on an accentric positioned axis in the central passageway for moving between a closed position and an open position. The leaflets are curved in a plane normal to the eccentric axis and positioned with the convex side of the leaflets facing each other when the leaflets are in the open position. Various parameters such as the curvature of the leaflets, the location of the eccentric axis, and the maximum opening angle of the leaflets are optimized according to the following performance criteria: maximize the minimum peak velocity through the valve, maximize the net stroke volume, and minimize the mean forward pressure difference, thereby reducing thrombosis and improving the hemodynamic performance.
NASA Astrophysics Data System (ADS)
Carminati, Carlo; Marmi, Stefano; Sauzin, David
2014-09-01
We consider the standard family of area-preserving twist maps of the annulus and the corresponding KAM curves. Addressing a question raised by Kolmogorov, we show that, instead of viewing these invariant curves as separate objects, each of which having its own Diophantine frequency, one can encode them in a single function of the frequency, which is naturally defined in a complex domain containing the real Diophantine frequencies and which is monogenic in the sense of Borel; this implies a remarkable property of quasianalyticity, a form of uniqueness of the monogenic continuation, although real frequencies constitute a natural boundary for the analytic continuation from the Weierstraß point of view because of the density of the resonances.
Knots, BPS States, and Algebraic Curves
NASA Astrophysics Data System (ADS)
Garoufalidis, Stavros; Kucharski, Piotr; Sułkowski, Piotr
2016-08-01
We analyze relations between BPS degeneracies related to Labastida-Mariño-Ooguri-Vafa (LMOV) invariants and algebraic curves associated to knots. We introduce a new class of such curves, which we call extremal A-polynomials, discuss their special properties, and determine exact and asymptotic formulas for the corresponding (extremal) BPS degeneracies. These formulas lead to nontrivial integrality statements in number theory, as well as to an improved integrality conjecture, which is stronger than the known M-theory integrality predictions. Furthermore, we determine the BPS degeneracies encoded in augmentation polynomials and show their consistency with known colored HOMFLY polynomials. Finally, we consider refined BPS degeneracies for knots, determine them from the knowledge of super-A-polynomials, and verify their integrality. We illustrate our results with twist knots, torus knots, and various other knots with up to 10 crossings.
PyTransit: Transit light curve modeling
NASA Astrophysics Data System (ADS)
Parviainen, Hannu
2015-05-01
PyTransit implements optimized versions of the Giménez and Mandel & Agol transit models for exoplanet transit light-curves. The two models are implemented natively in Fortran with OpenMP parallelization, and are accessed by an object-oriented python interface. PyTransit facilitates the analysis of photometric time series of exoplanet transits consisting of hundreds of thousands of data points, and of multipassband transit light curves from spectrophotometric observations. It offers efficient model evaluation for multicolour observations and transmission spectroscopy, built-in supersampling to account for extended exposure times, and routines to calculate the projected planet-to-star distance for circular and eccentric orbits, transit durations, and more.
Tilting train smooths out the curves
O'Connor, L.
1993-02-01
This article describes a Swedish train that leans into curves and speed around them safely at more than 100 miles per hour and is being tested on a tortuous railroad corridor in the Northeast United States. If the test proves successful, the train--the X2000--could become a fixture in the country's rail system. The train has flexible steering that allows the wheels to hug the rail and permits it to drive around turns faster than most other trains, according to Amtrak. Further, all of the train, expect the locomotive, tilts as it winds its way around the curves. The tilting compensates for the centrifugal force on passengers at high speeds. The X2000 is one of several train systems under consideration by railroads in the United States to improve the rail system in the country. Among the others are Germany's Inter-City Express (ICE) and France's Train a Grande Vitesse (TGV), built by GEC Alshthom (Paris).
An introduction to curved space-times.
NASA Astrophysics Data System (ADS)
Williams, R. M.
1991-07-01
These lectures focus on understanding relativity from a geometrical viewpoint, based on the use of space-time diagrams and without the tools of tensor calculus. After a brief discussion of flat space-times, curved space-times are introduced and it is shown how many of their properties may be deduced from their metric interval. The space-time around a spherically symmetric star and its possible collapse to form a black hole is described. Finally, some simple cosmological models are discussed, with emphasis on their causal properties and the existence of horizons. The titles of the lectures are: I. Flat space-times. II. Curved space-times. III. Spherical stars and stellar collapse. IV. Some simple cosmological models.
NURBS distance fields for extremely curved cracks
NASA Astrophysics Data System (ADS)
Sevilla, Ruben; Barbieri, Ettore
2014-12-01
This paper proposes for the first time an intrinsic enrichment for extremely curved cracks in a meshfree framework. The unique property of the proposed method lies in the exact geometric representation of cracks using non-uniform rational B-splines (NURBS). A distance function algorithm for NURBS is presented, resulting in a spatial field which is simultaneously discontinuous over the (finite) curved crack and continuous all around the crack tips. Numerical examples show the potential of the proposed approach and illustrate its advantages with respect to other techniques usually employed to model fracture, including standard finite elements with remeshing and the extended finite element method. This work represents a further step in an ongoing effort in the community to integrate computer aided design with numerical simulations.
Strong imploding shock - The representative curve
NASA Astrophysics Data System (ADS)
Mishkin, E. A.; Alejaldre, C.
1981-02-01
The representative curve of the ideal gas behind the front of a spherically or cylindrically asymmetric strong imploding shock is derived. The partial differential equations of mass, momentum and energy conservation are reduced to a set of ordinary differential equations by the method of quasi-separation of variables, following which the reduced pressure and density as functions of the radius with respect to the shock front are explicit functions of coordinates defining the phase plane of the self-similar solution. The curve in phase space representing the state of the imploded gas behind the shock front is shown to pass through the point where the reduced pressure is maximum, which is located somewhat behind the shock front and ahead of the tail of the shock.
Free Vibration of Curved Layered Composite Beams
NASA Astrophysics Data System (ADS)
Yavuz, Mustafa; Ergzgüven, M. Ertaç
In practice, fibrous and layered composite beams have periodically and locally curved layers because of the design considerations and manufacturing processes. In this study, the effect of these curvatures and composite material properties to the natural frequencies of the beams is investigated. The periodically curved layered composite material of the considered beam is modelled with the use of the continuum theory proposed by Akbarov and Guz. The free vibration problems are solved by employing the finite element method. Obtained natural frequencies of the beams are presented for the different parameters of the curvature, modulus of elasticity and support condition of the beams. For the case that the ratio of the modulus of elasticity of the layers equals to one and the parameter of the curvature equals to zero, the results converge to natural frequencies of a classical Euler-Bernoulli beam. Results are in good agreement with the literature.
Inferring mechanisms from dose-response curves
Chow, Carson C.; Ong, Karen M.; Dougherty, Edward J.; Simons, S. Stoney
2011-01-01
The steady state dose-response curve of ligand-mediated gene induction usually appears to precisely follow a first-order Hill equation (Hill coefficient equal to 1). Additionally, various cofactors/reagents can affect both the potency and the maximum activity of gene induction in a gene-specific manner. Recently, we have developed a general theory for which an unspecified sequence of steps or reactions yields a first-order Hill dose-response curve (FHDC) for plots of the final product vs. initial agonist concentration. The theory requires only that individual reactions “dissociate” from the downstream reactions leading to the final product, which implies that intermediate complexes are weakly bound or exist only transiently. We show how the theory can be utilized to make predictions of previously unidentified mechanisms and the site of action of cofactors/reagents. The theory is general and can be applied to any biochemical reaction that has a FHDC. PMID:21187235
Curved butterfly bileaflet prosthetic cardiac valve
McQueen, D.M.; Peskin, C.S.
1991-06-25
An annular valve body having a central passageway for the flow of blood with two curved leaflets is described. Each of the leaflets is pivotally supported on an accentric positioned axis in the central passageway for moving between a closed position and an open position. The leaflets are curved in a plane normal to the eccentric axis and positioned with the convex side of the leaflets facing each other when the leaflets are in the open position. Various parameters such as the curvature of the leaflets, the location of the eccentric axis, and the maximum opening angle of the leaflets are optimized according to the following performance criteria: maximize the minimum peak velocity through the valve, maximize the net stroke volume, and minimize the mean forward pressure difference, thereby reducing thrombosis and improving the hemodynamic performance. 26 figures.
Knots, BPS States, and Algebraic Curves
NASA Astrophysics Data System (ADS)
Garoufalidis, Stavros; Kucharski, Piotr; Sułkowski, Piotr
2016-07-01
We analyze relations between BPS degeneracies related to Labastida-Mariño-Ooguri-Vafa (LMOV) invariants and algebraic curves associated to knots. We introduce a new class of such curves, which we call extremal A-polynomials, discuss their special properties, and determine exact and asymptotic formulas for the corresponding (extremal) BPS degeneracies. These formulas lead to nontrivial integrality statements in number theory, as well as to an improved integrality conjecture, which is stronger than the known M-theory integrality predictions. Furthermore, we determine the BPS degeneracies encoded in augmentation polynomials and show their consistency with known colored HOMFLY polynomials. Finally, we consider refined BPS degeneracies for knots, determine them from the knowledge of super-A-polynomials, and verify their integrality. We illustrate our results with twist knots, torus knots, and various other knots with up to 10 crossings.
Curve fitting air sample filter decay curves to estimate transuranic content.
Hayes, Robert B; Chiou, Hung Cheng
2004-01-01
By testing industry standard techniques for radon progeny evaluation on air sample filters, a new technique is developed to evaluate transuranic activity on air filters by curve fitting the decay curves. The industry method modified here is simply the use of filter activity measurements at different times to estimate the air concentrations of radon progeny. The primary modification was to not look for specific radon progeny values but rather transuranic activity. By using a method that will provide reasonably conservative estimates of the transuranic activity present on a filter, some credit for the decay curve shape can then be taken. By carrying out rigorous statistical analysis of the curve fits to over 65 samples having no transuranic activity taken over a 10-mo period, an optimization of the fitting function and quality tests for this purpose was attained. PMID:14695010
OPTICAL PHASE CURVES OF KEPLER EXOPLANETS
Esteves, Lisa J.; De Mooij, Ernst J. W.; Jayawardhana, Ray E-mail: demooij@astro.utoronto.ca
2013-07-20
We conducted a comprehensive search for optical phase variations of all close-in (a/R{sub *} < 10) planet candidates in 15 quarters of Kepler space telescope data. After correcting for systematics, we found eight systems that show secondary eclipses as well as phase variations. Of these, five (Kepler-5, Kepler-6, Kepler-8, KOI-64, and KOI-2133) are new and three (TrES-2, HAT-P-7, and KOI-13) have published phase curves, albeit with many fewer observations. We model the full phase curve of each planet candidate, including the primary and secondary transits, and derive their albedos, dayside and nightside temperatures, ellipsoidal variations, and Doppler beaming. We find that KOI-64 and KOI-2133 have nightside temperatures well above their equilibrium values (while KOI-2133 also has an albedo, >1), so we conclude that they are likely to be self-luminous objects rather than planets. The other six candidates have characteristics consistent with their being planets with low geometric albedos (<0.3). For TrES-2 and KOI-13, the Kepler bandpass appears to probe atmospheric layers hotter than the planet's equilibrium temperature. For KOI-13, we detect a never-before-seen third cosine harmonic with an amplitude of 6.7 {+-} 0.3 ppm and a phase shift of -1.1 {+-} 0.1 rad in the phase curve residual, possibly due to its spin-orbit misalignment. We report derived planetary parameters for all six planets, including masses from ellipsoidal variations and Doppler beaming, and compare our results to published values when available. Our results nearly double the number of Kepler exoplanets with measured phase curve variations, thus providing valuable constraints on the properties of hot Jupiters.
Analysis of light curve of LP Camelopardalis
NASA Astrophysics Data System (ADS)
Prudil, Z.; Skarka, M.; Zejda, M.
2016-05-01
We present photometric analysis of the RRab type pulsating star LP Cam. The star was observed at Brno Observatory and Planetarium during nine nights. Measurements were calibrated to the Johnson photometric system. Four captured and thirteen previously published maxima timings allowed us to refine the pulsation period and the zero epoch. The light curve was Fourier decomposed to estimate physical parameters using empirical relations. Our results suggest that LP Cam is a common RR Lyrae star with high, almost solar metallicity.
Atlas of Secular Light Curves of Comets
NASA Astrophysics Data System (ADS)
Ferrin, Ignacio
2007-12-01
We have completed work on the secular light curves of 30 periodic and non-periodic comets. The objectives and approach of this project has been explained in Ferrin (Icarus, 178, 493-516, 2005). Each comet requires 2 plots. The time plot shows the reduced (to Δ = 1 AU) magnitude of the comet as a function of time, thus displaying the brightness history of the object. The log plot is a reflected double log plot. The reflection takes place at R=1 AU, to allow the determination of the absolute magnitude by extrapolation. 22 photometric parameters are measured from the plots, most of them new. The plots have been collected in a document that constitutes "The Atlas". We have defined a photometric age, P-AGE, that attempts to measure the age of a comet based on its activity. P-AGE has been scaled to human ages to help in its interpretation. We find that comets Hale-Bopp and 29P/SW 1, are baby comets (P-AGE < 3 comet years), while 107P, 162P and 169P are methuselah comets (P-AGE > 100 cy). The secular light curve of 9P/Tempel 1 exhibits sublimation due to H2O and due to CO. Comet 67P/Churyumov-Gerasimento to be visited by the Rossetta spacecraft in 2014 exhibits a photometric anomaly. Comet 65P/Gunn exhibits a lag in maximum brightness of LAG = + 254 days after perihelion. We suggest that the pole is pointing to the sun at that time. The secular light curves will be presented and a preliminary interpretation will be advanced. The secular light curves present complexity beyond current understanding. The observations described in this work were carried out at the National Observatory of Venezuela (ONV), managed by the Center for Research in Astronomy (CIDA), for the Ministry of Science and Technology (MinCyT).
Making Internal Molds Of Long, Curved Tubes
NASA Technical Reports Server (NTRS)
Burley, Richard K.
1989-01-01
Mold material carried to internal weld joint and removed after impression taken. Remotely operated device makes impression mold of interior surface of tube at weld joint. Mold provides indication of extent of mismatch between members at joint. Maneuvered to weld inspected through curved tube 3 in. in diameter by 50 in. long. Readily adapted to making molds to measure depth of corrosion in boiler tubes or other pipes.
The Astral Curved Disc of Chevroches (France)
NASA Astrophysics Data System (ADS)
Devevey, F. Rousseau, A.
2009-08-01
The excavation of the unexplored secondary agglomeration in Chevroches (Nièvre), from 2001 to 2002, directed by F. Devevey (INRAP), has led to the discovery of an astrological bronze curved disc of a type unknown in the ancient world; it is inscribed with three lines in Greek transcribing Egyptian an Roman months, and the twelve signs of the zodiac. This article presents the first observations.
Science 101: What Makes a Curveball Curve?
ERIC Educational Resources Information Center
Robertson, William C.
2009-01-01
Ah, springtime, and young people's thoughts turn to... baseball, of course. But this column is not about "how" to throw a curveball, so you'll have to look that up on your own. Here, the focus is on the "why" of the curveball. There are two different things that cause a spinning ball to curve. One is known as the "Bernoulli effect" and the other…
NASA Technical Reports Server (NTRS)
Cole, S. W.
1983-01-01
Electronic load circuit for displaying current/voltage characteristic curves of power sources uses low-cost low-power CMOS operational amplifiers to control load current flowing through power MOSFET Q2 and main load transistor Q3. Thermal cutoff device turns off transistor Q3 in case of overload. To maximize battery life, battery is connected via "push-to-read" momentary-contact pushbutton switch.
Explicit travelling waves and invariant algebraic curves
NASA Astrophysics Data System (ADS)
Gasull, Armengol; Giacomini, Hector
2015-06-01
We introduce a precise definition of algebraic travelling wave solution of n-th order partial differential equations and prove that the only algebraic travelling waves solutions for the celebrated Fisher-Kolmogorov equation are the ones found in 1979 by Ablowitz and Zeppetella. This question is equivalent to study when an associated one-parameter family of planar ordinary differential systems has invariant algebraic curves.
Lower extremity kinematics of athletics curve sprinting.
Alt, Tobias; Heinrich, Kai; Funken, Johannes; Potthast, Wolfgang
2015-01-01
Curve running requires the generation of centripetal force altering the movement pattern in comparison to the straight path run. The question arises which kinematic modulations emerge while bend sprinting at high velocities. It has been suggested that during curve sprints the legs fulfil different functions. A three-dimensional motion analysis (16 high-speed cameras) was conducted to compare the segmental kinematics of the lower extremity during the stance phases of linear and curve sprints (radius: 36.5 m) of six sprinters of national competitive level. Peak joint angles substantially differed in the frontal and transversal plane whereas sagittal plane kinematics remained unchanged. During the prolonged left stance phase (left: 107.5 ms, right: 95.7 ms, straight: 104.4 ms) the maximum values of ankle eversion (left: 12.7°, right: 2.6°, straight: 6.6°), hip adduction (left: 13.8°, right: 5.5°, straight: 8.8°) and hip external rotation (left: 21.6°, right: 12.9°, straight: 16.7°) were significantly higher. The inside leg seemed to stabilise the movement in the frontal plane (eversion-adduction strategy) whereas the outside leg provided and controlled the motion in the horizontal plane (rotation strategy). These results extend the principal understanding of the effects of curve sprinting on lower extremity kinematics. This helps to increase the understanding of nonlinear human bipedal locomotion, which in turn might lead to improvements in athletic performance and injury prevention. PMID:25495196
NASA Astrophysics Data System (ADS)
Tewes, Malte
2015-09-01
PyCS is a software toolbox to estimate time delays between multiple images of strongly lensed quasars, from resolved light curves such as obtained by the COSMOGRAIL monitoring program. The pycs package defines a collection of classes and high level functions, that you can script in a flexible way. PyCS makes it easy to compare different point estimators (including your own) without much code integration. The package heavily depends on numpy, scipy, and matplotlib.
Revisiting the learning curve (once again)
Glautier, Steven
2013-01-01
The vast majority of published work in the field of associative learning seeks to test the adequacy of various theoretical accounts of the learning process using average data. Of course, averaging hides important information, but individual departures from the average are usually designated “error” and largely ignored. However, from the perspective of an individual differences approach, this error is the data of interest; and when associative models are applied to individual learning curves the error is substantial. To some extent individual differences can be reasonably understood in terms of parametric variations of the underlying model. Unfortunately, in many cases, the data cannot be accomodated in this way and the applicability of the underlying model can be called into question. Indeed several authors have proposed alternatives to associative models because of the poor fits between data and associative model. In the current paper a novel associative approach to the analysis of individual learning curves is presented. The Memory Environment Cue Array Model (MECAM) is described and applied to two human predictive learning datasets. The MECAM is predicated on the assumption that participants do not parse the trial sequences to which they are exposed into independent episodes as is often assumed when learning curves are modeled. Instead, the MECAM assumes that learning and responding on a trial may also be influenced by the events of the previous trial. Incorporating non-local information the MECAM produced better approximations to individual learning curves than did the Rescorla–Wagner Model (RWM) suggesting that further exploration of the approach is warranted. PMID:24421774
Atlas of secular light curves of comets
NASA Astrophysics Data System (ADS)
Ferrín, Ignacio
2010-02-01
In this work we have compiled 37,692 observations of 27 periodic and non-periodic comets to create the secular light curves (SLCs), using two plots per comet. The data have been reduced homogeneously. Our overriding goal is to learn the properties of the ensemble of comets. More than 30 parameters are listed, of which over ˜20 are new and measured from the plots. We define two ages for a comet using activity as a proxy, the photometric age P-AGE, and the time-age, T-AGE. It is shown that these parameters are robust, implying that the input data can have significant errors but P-AGE and T-AGE come out with small errors. This is due to their mathematical definition. It is shown that P-AGE classifies comets by shape of their light curve. The value of this Atlas is twofold: The SLCs not only show what we know, but also show what we do not know, thus pointing the way to meaningful observations. Besides their scientific value, these plots are useful for planning observations. The SLCs have not been modeled, and there is no cometary light curve standard model as there is for some variable stars (i.e. eclipsing binaries). Comets are classified by age and size. In this way it is found that 29P/Schwassmann-Wachmann 1 is a baby goliath comet, while C/1983 J1 Sugano-Saigusa-Fujikawa is a middle age dwarf. There are new classes of comets based on their photometric properties. The secular light curves presented in this Atlas exhibit complexity beyond current understanding.
Potential Energy Curves of Hydrogen Fluoride
NASA Technical Reports Server (NTRS)
Fallon, Robert J.; Vanderslice, Joseph T.; Mason, Edward A.
1960-01-01
Potential energy curves for the X(sup 1)sigma+ and V(sup 1)sigma+ states of HF and DF have been calculated by the Rydberg-Klein-Rees method. The results calculated from the different sets of data for HF and DF are found to be in very good agreement. The theoretical results of Karo are compared to the experimental results obtained here.
RF Curves for Extraction from the Accumulator
McGinnis, Dav; /Fermilab
2002-03-10
Since the start of Run IIa, the RF curves for the extraction process from the Accumulator have been based on an algorithm described in Pbar Note 636. There are a number of problems with this procedure that result in a dilution of the longitudinal phase space of the extracted beam. The procedure consists of a number of steps in which the frequency curve during each process is a linear time ramp. For a constant bend field, the synchronous phase angle is given as: {Lambda} = sin({phi}{sub s}) = -h/{eta} (1/f{sub rf}){sup 2}df{sub rf}/dt/qV/pc where h is the harmonic number of the RF. Equation (1) shows that if the frequency curve consists of a number of linear time ramps with different slopes, there will be discontinuities in the synchronous phase. These discontinuities in the synchronous phase will lead to dipole oscillations of the beam in the RF bucket. The discontinuities observed for the present RF curves are about 10 degrees. In the procedure outlined in Pbar Note 636, the RF bucket is formed on the high energy edge of the rectangular momentum distribution. As the RF bucket is pulled away from the core, it is also programmed to increase in area. If the distribution is not perfectly rectangular, or if the bucket is not formed at the edge of the distribution, the growing bucket will gather up more particles at the edges of the bucket resulting in a substantial increase of longitudinal emittance. Finally, it is fairly difficult to prepare a rectangular momentum distribution and keep it rectangular for extended periods of time. Once the rectangular distribution is prepared, the core momentum cooling must be turned off. If there is a delay in the extraction process, the sharp edges of the rectangular distribution will soon diffuse. With the momentum cooling disabled, the longitudinal emittance of the core will grow resulting in larger longitudinal emittances for the extracted beam.
Ab initio melting curve of osmium
NASA Astrophysics Data System (ADS)
Burakovsky, L.; Burakovsky, N.; Preston, D. L.
2015-11-01
The melting curve of osmium up to a pressure P of 500 GPa is obtained from an extensive suite of ab initio quantum molecular dynamics (QMD) simulations using the Z method. The ab initio P =0 melting point of Os is 3370 ±75 K; this range encompasses all of the available data in the literature and corroborates the conclusion of J. W. Arblaster [Platinum Metals Rev. 49, 166 (2005)], 10.1595/147106705X70264 that the melting temperature of pure Os is 3400 ±50 K and that the 3300 K typically quoted in the literature is the melting point of impure Os. The T =0 equation of state (EOS) of Os and the P dependence of the optimized c /a ratio for the hexagonal unit cell, both to pressures ˜900 GPa, are obtained in the ab initio approach as validation of its use. Although excellent agreement with the available experimental data (P ≲80 GPa) is found, it is the third-order Birch-Murnaghan EOS with B0'=5 rather than the more widely accepted B0'=4 that describes the QMD data to higher pressures, in agreement with the more recent experimental EOS by Godwal et al. The theoretical melting curve of Os obtained earlier by Joshi et al. is shown to be inconsistent with our QMD results, and the possible reason for this discrepancy is suggested. Regularities in the melting curves of Os and five other third-row transition metals (Ta, W, Re, Pt, Au) could be used to estimate the currently unknown melting curves of Hf and Ir.
Perfect bell nozzle parametric and optimization curves
NASA Technical Reports Server (NTRS)
Tuttle, J. L.; Blount, D. H.
1983-01-01
Nozzle contour data for untruncated Bell nozzles with expansion area ratios to 6100 and a specific heat ratio of 1.2 are provided. Curves for optimization of nozzles for maximum thrust coefficient within a given length, surface area, or area ratio are included. The nozzles are two dimensional axisymmetric and calculations were performed using the method of characteristics. Drag due to wall friction was included in the final thrust coefficient.
Shape optimization of self-avoiding curves
NASA Astrophysics Data System (ADS)
Walker, Shawn W.
2016-04-01
This paper presents a softened notion of proximity (or self-avoidance) for curves. We then derive a sensitivity result, based on shape differential calculus, for the proximity. This is combined with a gradient-based optimization approach to compute three-dimensional, parameterized curves that minimize the sum of an elastic (bending) energy and a proximity energy that maintains self-avoidance by a penalization technique. Minimizers are computed by a sequential-quadratic-programming (SQP) method where the bending energy and proximity energy are approximated by a finite element method. We then apply this method to two problems. First, we simulate adsorbed polymer strands that are constrained to be bound to a surface and be (locally) inextensible. This is a basic model of semi-flexible polymers adsorbed onto a surface (a current topic in material science). Several examples of minimizing curve shapes on a variety of surfaces are shown. An advantage of the method is that it can be much faster than using molecular dynamics for simulating polymer strands on surfaces. Second, we apply our proximity penalization to the computation of ideal knots. We present a heuristic scheme, utilizing the SQP method above, for minimizing rope-length and apply it in the case of the trefoil knot. Applications of this method could be for generating good initial guesses to a more accurate (but expensive) knot-tightening algorithm.
Incorporating Experience Curves in Appliance Standards Analysis
Garbesi, Karina; Chan, Peter; Greenblatt, Jeffery; Kantner, Colleen; Lekov, Alex; Meyers, Stephen; Rosenquist, Gregory; Buskirk, Robert Van; Yang, Hung-Chia; Desroches, Louis-Benoit
2011-10-31
The technical analyses in support of U.S. energy conservation standards for residential appliances and commercial equipment have typically assumed that manufacturing costs and retail prices remain constant during the projected 30-year analysis period. There is, however, considerable evidence that this assumption does not reflect real market prices. Costs and prices generally fall in relation to cumulative production, a phenomenon known as experience and modeled by a fairly robust empirical experience curve. Using price data from the Bureau of Labor Statistics, and shipment data obtained as part of the standards analysis process, we present U.S. experience curves for room air conditioners, clothes dryers, central air conditioners, furnaces, and refrigerators and freezers. These allow us to develop more representative appliance price projections than the assumption-based approach of constant prices. These experience curves were incorporated into recent energy conservation standards for these products. The impact on the national modeling can be significant, often increasing the net present value of potential standard levels in the analysis. In some cases a previously cost-negative potential standard level demonstrates a benefit when incorporating experience. These results imply that past energy conservation standards analyses may have undervalued the economic benefits of potential standard levels.
Capillary migration of microdisks on curved interfaces.
Yao, Lu; Sharifi-Mood, Nima; Liu, Iris B; Stebe, Kathleen J
2015-07-01
The capillary energy landscape for particles on curved fluid interfaces is strongly influenced by the particle wetting conditions. Contact line pinning has now been widely reported for colloidal particles, but its implications in capillary interactions have not been addressed. Here, we present experiment and analysis for disks with pinned contact lines on curved fluid interfaces. In experiment, we study microdisk migration on a host interface with zero mean curvature; the microdisks have contact lines pinned at their sharp edges and are sufficiently small that gravitational effects are negligible. The disks migrate away from planar regions toward regions of steep curvature with capillary energies inferred from the dissipation along particle trajectories which are linear in the deviatoric curvature. We derive the curvature capillary energy for an interface with arbitrary curvature, and discuss each contribution to the expression. By adsorbing to a curved interface, a particle eliminates a patch of fluid interface and perturbs the surrounding interface shape. Analysis predicts that perfectly smooth, circular disks do not migrate, and that nanometric deviations from a planar circular, contact line, like those around a weakly roughened planar disk, will drive migration with linear dependence on deviatoric curvature, in agreement with experiment. PMID:25618486
Psychophysical tuning curves at very high frequencies
NASA Astrophysics Data System (ADS)
Yasin, Ifat; Plack, Christopher J.
2005-10-01
For most normal-hearing listeners, absolute thresholds increase rapidly above about 16 kHz. One hypothesis is that the high-frequency limit of the hearing-threshold curve is imposed by the transmission characteristics of the middle ear, which attenuates the sound input [Masterton et al., J. Acoust. Soc. Am. 45, 966-985 (1969)]. An alternative hypothesis is that the high-frequency limit of hearing is imposed by the tonotopicity of the cochlea [Ruggero and Temchin, Proc. Nat. Acad. Sci. U.S.A. 99, 13206-13210 (2002)]. The aim of this study was to test these hypotheses. Forward-masked psychophysical tuning curves (PTCs) were derived for signal frequencies of 12-17.5 kHz. For the highest signal frequencies, the high-frequency slopes of some PTCs were steeper than the slope of the hearing-threshold curve. The results also show that the human auditory system displays frequency selectivity for characteristic frequencies (CFs) as high as 17 kHz, above the frequency at which absolute thresholds begin to increase rapidly. The findings suggest that, for CFs up to 17 kHz, the high-frequency limitation in humans is imposed in part by the middle-ear attenuation, and not by the tonotopicity of the cochlea.
D Catenary Curve Fitting for Geometric Calibration
NASA Astrophysics Data System (ADS)
Chan, T.-O.; Lichti, D. D.
2011-09-01
In modern road surveys, hanging power cables are among the most commonly-found geometric features. These cables are catenary curves that are conventionally modelled with three parameters in 2D Cartesian space. With the advent and popularity of the mobile mapping system (MMS), the 3D point clouds of hanging power cables can be captured within a short period of time. These point clouds, similarly to those of planar features, can be used for feature-based self-calibration of the system assembly errors of an MMS. However, to achieve this, a well-defined 3D equation for the catenary curve is needed. This paper proposes three 3D catenary curve models, each having different parameters. The models are examined by least squares fitting of simulated data and real data captured with an MMS. The outcome of the fitting is investigated in terms of the residuals and correlation matrices. Among the proposed models, one of them could estimate the parameters accurately and without any extreme correlation between the variables. This model can also be applied to those transmission lines captured by airborne laser scanning or any other hanging cable-like objects.
The biology behind lichenometric dating curves.
Loso, Michael G; Doak, Daniel F
2006-03-01
Lichenometry is used to date late-Holocene terminal moraines that record glacier fluctuations. Traditionally, it relies upon dating curves that relate diameters of the largest lichens in a population to surface ages. Although widely used, the technique remains controversial, in part because lichen biology is poorly understood. We use size-frequency distributions of lichens growing on well-dated surfaces to fit demographic models for Rhizocarpon geographicum and Pseudophebe pubescens, two species commonly used for lichenometry. We show that both species suffer from substantial mortality of 2-3% per year, and grow slowest when young-trends that explain a long-standing contradiction between the literatures of lichenometry and lichen biology. Lichenometrists interpret the shape of typical dating curves to indicate a period of rapid juvenile "great growth," contrary to the growth patterns expected by biologists. With a simulation, we show how the "great growth" pattern can be explained by mortality alone, which ensures that early colonists are rarely found on the oldest surfaces. The consistency of our model predictions with biological theory and observations, and with dozens of lichenometric calibration curves from around the world, suggests opportunities to assess quantitatively the accuracy and utility of this common dating technique. PMID:16237538
Quantum coherence and closed timelike curves
NASA Astrophysics Data System (ADS)
Hawking, S. W.
1995-11-01
Various calculations of the S matrix have shown that it seems to be nonunitary for interacting fields when there are closed timelike curves. It is argued that this is because there is loss of quantum coherence caused by the fact that part of the quantum state circulates on the closed timelike curves and is not measured at infinity. A prescription is given for calculating the superscattering matrix on spacetimes whose parameters can be analytically continued to obtain a Euclidean metric. It is illustrated by a discussion of a spacetime in which two disks in flat space are indentified. If the disks have an imaginary time separation, this corresponds to a heat bath. An external field interacting with the heat bath will lose quantum coherence. One can then analytically continue to an almost real separation of the disks. This will give closed timelike curves but one will still get loss of quantum coherence. A comparison is made with the work of authors who find a nonunitary S matrix. It is shown that this is because the does not factor into an S matrix and its adjoint when the spacetime does not have the property of asymptotic completeness.
NASA Astrophysics Data System (ADS)
Shrader, Chris; Titarchuk, Lev
2002-04-01
We describe recent work in which we revisit the database of historical X-Ray nova (XRN) light curves compiled by Chen, Shrader & Livio (1997, ApJ 491, 312), augmented by subsequent events recorded by RXTE, in an attempt to gain a better understanding of the outburst phenomenon. Previously, we demonstrated that, given the occurrence of an instability in the mass transfer rate from the secondary, a model based on viscous diffusion of matter through the disk (Wood et al, 2001, astro-ph/0108189) we could reproduce a large number of fast-rise exponential decay (FRED) type XRN light curves. We augment this effort by considering deviations from the FRED form, such as plateaus and power-law decay forms are also considered within this framework. More complex structures are, in a number of instances, successfully modeled as a superposition of mass- injection, diffusive propagation events. In addition, for a large number of cases, we perform a joint analysis of optical light curve data. In particular, we will attempt to characterize empirical characteristics such as possible tie lags, and relative decay time scales, and then interpret such effects withing the context of diffusive propagation in the disk.
Characterization of running with compliant curved legs.
Jun, Jae-Yun; Clark, Jonathan E
2015-08-01
Running with compliant curved legs involves the progression of the center of pressure, the changes of both the leg's stiffness and effective rest length, and the shift of the location of the maximum stress point along the leg. These phenomena are product of the geometric and material properties of these legs, and the rolling motion produced during stance. We examine these aspects with several reduced-order dynamical models to relate the leg's design parameters (such as normalized foot radius, leg's effective stiffness, location of the maximum stress point and leg shape) to running performance (such as robustness and efficiency). By using these models, we show that running with compliant curved legs can be more efficient, robust with fast recovery behavior from perturbations than running with compliant straight legs. Moreover, the running performance can be further improved by tuning these design parameters in the context of running with rolling. The results shown in this work may serve as potential guidance for future compliant curved leg designs that may further improve the running performance. PMID:26151098
SMOOTHING ROTATION CURVES AND MASS PROFILES
Berrier, Joel C.; Sellwood, J. A.
2015-02-01
We show that spiral activity can erase pronounced features in disk galaxy rotation curves. We present simulations of growing disks, in which the added material has a physically motivated distribution, as well as other examples of physically less realistic accretion. In all cases, attempts to create unrealistic rotation curves were unsuccessful because spiral activity rapidly smoothed away features in the disk mass profile. The added material was redistributed radially by the spiral activity, which was itself provoked by the density feature. In the case of a ridge-like feature in the surface density profile, we show that two unstable spiral modes develop, and the associated angular momentum changes in horseshoe orbits remove particles from the ridge and spread them both inward and outward. This process rapidly erases the density feature from the disk. We also find that the lack of a feature when transitioning from disk to halo dominance in the rotation curves of disk galaxies, the so called ''disk-halo conspiracy'', could also be accounted for by this mechanism. We do not create perfectly exponential mass profiles in the disk, but suggest that this mechanism contributes to their creation.
Smoothing Rotation Curves and Mass Profiles
NASA Astrophysics Data System (ADS)
Berrier, Joel C.; Sellwood, J. A.
2015-02-01
We show that spiral activity can erase pronounced features in disk galaxy rotation curves. We present simulations of growing disks, in which the added material has a physically motivated distribution, as well as other examples of physically less realistic accretion. In all cases, attempts to create unrealistic rotation curves were unsuccessful because spiral activity rapidly smoothed away features in the disk mass profile. The added material was redistributed radially by the spiral activity, which was itself provoked by the density feature. In the case of a ridge-like feature in the surface density profile, we show that two unstable spiral modes develop, and the associated angular momentum changes in horseshoe orbits remove particles from the ridge and spread them both inward and outward. This process rapidly erases the density feature from the disk. We also find that the lack of a feature when transitioning from disk to halo dominance in the rotation curves of disk galaxies, the so called "disk-halo conspiracy," could also be accounted for by this mechanism. We do not create perfectly exponential mass profiles in the disk, but suggest that this mechanism contributes to their creation.
Ab-inition melting curve of titanium
NASA Astrophysics Data System (ADS)
Stutzmann, Vincent; Bouchet, Johann; Bottin, Francois
2014-03-01
Thermodynamical properties of titanium are of great interest for aerospace and aviation industries and many studies are done in order to understand its behaviour under pressure (P) and temperature (T) : phase transitions at low T, melting curve at high T and P. In this work we compute the first ab-initio melting curve of titanium. This one is obtained with the Abinit package using DFT, in the GGA approximation, and in the framework of the projector augmented wave method (PAW). At first, we perform ground state calculations and study the five allotropic phases of titanium. Two PAW atomic data are generated with two different cutoff radius. The larger one gives results near previews ab-initio calculations, whereas the smaller one gives results near all electron calculation. Using the second PAW atomic data and performing ab-initio molecular dynamic simulations, we then compute the melting curve of titanium with three different methods. Results show relevance of our calculations, but also discrepencies with experimental data.
A learning curve for solar thermal power
NASA Astrophysics Data System (ADS)
Platzer, Werner J.; Dinter, Frank
2016-05-01
Photovoltaics started its success story by predicting the cost degression depending on cumulated installed capacity. This so-called learning curve was published and used for predictions for PV modules first, then predictions of system cost decrease also were developed. This approach is less sensitive to political decisions and changing market situations than predictions on the time axis. Cost degression due to innovation, use of scaling effects, improved project management, standardised procedures including the search for better sites and optimization of project size are learning effects which can only be utilised when projects are developed. Therefore a presentation of CAPEX versus cumulated installed capacity is proposed in order to show the possible future advancement of the technology to politics and market. However from a wide range of publications on cost for CSP it is difficult to derive a learning curve. A logical cost structure for direct and indirect capital expenditure is needed as the basis for further analysis. Using derived reference cost for typical power plant configurations predictions of future cost have been derived. Only on the basis of that cost structure and the learning curve levelised cost of electricity for solar thermal power plants should be calculated for individual projects with different capacity factors in various locations.
New configuration factors for curved surfaces
NASA Astrophysics Data System (ADS)
Cabeza-Lainez, Jose M.; Pulido-Arcas, Jesus A.
2013-03-01
Curved surfaces have not been thoroughly considered in radiative transfer analysis mainly due to the difficulties arisen in the integration process and perhaps because of the lack of spatial vision of the researchers. It is a fact, especially for architectural lighting, that when concave geometries appear inside a curved space, they are mostly avoided. In this way, a vast repertoire of significant forms is neglected and energy waste is evident. Starting from the properties of volumes enclosed by the minimum number of surfaces, the authors formulate, with little calculus, new simple laws, which enable them to discover a set of configuration factors for caps and various segments of the sphere. The procedure is subsequently extended to previously unimagined surfaces as the paraboloid, the ellipsoid or the cone. Appropriate combination of the said forms with right truncated cones produces several complex volumes, often used in architectural and engineering creations and whose radiative performance could not be accurately predicted for decades. To complete the research, a new method for determining interreflections in curved volumes is also presented. Radiative transfer simulation benefits from these findings, as the simplicity of the results has led the authors to create innovative software more efficient for design and evaluation and applicable to emerging fields like LED lighting.
Environment Dependence of Interstellar Extinction Curves
NASA Astrophysics Data System (ADS)
Jenniskens, P.; Greenberg, J. M.
1993-07-01
The IUE interstellar extinction curves published by Aiello et al. (1988) are decomposed into a bump, linear rise and FUV non-linear rise, in the parameterization scheme of Fitzpatrick & Massa (1990). The parameters of the 115 extinction curves are given. The lines of sight are characterized from the IRAS Skyflux and Point Source Catalogue data. Mean extinction curves for each of the environments are given. The following environment specific behaviour has been found. We confirm that the linear rise is systematically less in dense media, corresponding to an accretion of their carriers on big grains in such environments. The bump is not weakened in dense media, but is sensitive to the presence of strong UV radiation fields. In HII regions we note abnormal behaviour of the bump width and a correlation of bump position and bump width. This argues against a removal of the bump carrier in HII regions by sticking to big grains. No environment specific behaviour for the FUV non-linear rise was noted except for a weak dependence on E(B-V)/d, notably in HII regions.
Breakthrough curve moments scaling in hyporheic exchange
NASA Astrophysics Data System (ADS)
Bellin, A.; Tonina, D.; Marzadri, A.
2015-02-01
The interaction between stream flow and bed forms creates an uneven distribution of near-bed energy heads, which is the driving force of hyporheic exchange. Owing to the large disparity of advection characteristic times in the stream and within the hyporheic zone, solute mass exchange is often modeled by considering the latter as an immobile region. In a recent contribution Gónzalez-Pinzón et al. (2013) showed that existing models employing this hypothesis are structurally inconsistent with the scaling revealed by the analysis of 384 breakthrough curves collected in 44 streams across five continents. Motivated by this result, we analyze the scaling characteristics of a model that we recently developed by combining the analytical solution of the advective flow within the hyporheic zone with a Lagrangian solute transport model. Results show that similarly to the experimental data our model predicts breakthrough curves with a constant skewness, irrespective of the stream size, and that the scaling of the first three moments observed by Gónzalez-Pinzón et al. (2013) is also respected. Moreover, we propose regression curves that relate the first three moments of the residence time distribution with the alternate bar dimensionless depth (YBM*), a quantity that is easily measurable in the field. The connection between BTC moments and YBM* opens new possibilities for modeling transport processes at the catchment scale.
Variation of curve number with storm depth
NASA Astrophysics Data System (ADS)
Banasik, K.; Hejduk, L.
2012-04-01
The NRCS Curve Number (known also as SCS-CN) method is well known as a tool in predicting flood runoff depth from small ungauged catchment. The traditional way of determination the CNs, based on soil characteristics, land use and hydrological conditions, seemed to have tendency to overpredict the floods in some cases. Over 30 year rainfall-runoff data, collected in two small (A=23.4 & 82.4 km2), lowland, agricultural catchments in Center of Poland (Banasik & Woodward 2010), were used to determine runoff Curve Number and to check a tendency of changing. The observed CN declines with increasing storm size, which according recent views of Hawkins (1993) could be classified as a standard response of watershed. The analysis concluded, that using CN value according to the procedure described in USDA-SCS Handbook one receives representative value for estimating storm runoff from high rainfall depths in the analyzes catchments. This has been confirmed by applying "asymptotic approach" for estimating the watershed curve number from the rainfall-runoff data. Furthermore, the analysis indicated that CN, estimated from mean retention parameter S of recorded events with rainfall depth higher than initial abstraction, is also approaching the theoretical CN. The observed CN, ranging from 59.8 to 97.1 and from 52.3 to 95.5, in the smaller and the larger catchment respectively, declines with increasing storm size, which has been classified as a standard response of watershed. The investigation demonstrated also changeability of the CN during a year, with much lower values during the vegetation season. Banasik K. & D.E. Woodward (2010). "Empirical determination of curve number for a small agricultural watrshed in Poland". 2nd Joint Federal Interagency Conference, Las Vegas, NV, June 27 - July 1, 2010 (http://acwi.gov/sos/pubs/2ndJFIC/Contents/10E_Banasik_ 28_02_10. pdf). Hawkins R. H. (1993). "Asymptotic determination of curve numbers from data". Journal of Irrigation and Drainage
Phase-ordering kinetics on curved surfaces
NASA Astrophysics Data System (ADS)
Schoenborn, Oliver Lars
I investigate phase-ordering kinetics on static curved surfaces, starting from a well-known time-dependent Ginzburg-Landau equation, known as model A and valid in flat two-dimensional systems, and generalizing this to apply on curved surfaces. I develop and implement an interface formalism for model A, valid in both curved and flat surfaces. This is based on an interface velocity equation explicitly showing how interface motion couples to local surface geometry. I discuss extensively both theoretical and numerical aspects of this formalism. I derive a coupled set of curvature equations and use them to obtain an approximate expression for the curvature autocorrelation function (CAF) in the flat case. This is compared for the first time to numerical simulation results and shows that the CAF provides dynamical information not readily available from the traditional order-parameter structure-factor, yet is far easier to compute than the latter. A dominant length-scale is observed for the first time, in the domain interface undulations, even in Euclidean model A dynamics. I discuss how this affects the interpretation of what is needed for a system to exhibit dynamical scaling. I look at the effect of surface Gauss curvature on the growth rate of domains and show that when the phase-ordering occurs on a corrugated surface, metastable long-range disorder may result. I show how these effects cause a break-down of dynamical scaling and power-law growth, how they bring about the elimination of the zero-temperature fixed point of Euclidean model A, and how phase-ordering in curved lipid-bilayer membranes should be affected. A new very-late stage regime appears for simulations of model A on sinusoid (i.e. egg-carton-like) surfaces. These features indicate that thermal noise should be included in future studies of phase ordering kinetics on curved surfaces. They also indicate that even before the order-parameter is explicitly coupled to surface quantities such as the local mean
Light Curve Models for Type IA Supernovae
NASA Astrophysics Data System (ADS)
Dominguez, Inmaculada
1993-05-01
The most widely accepted scenario for Type Ia supernovae is the thermonuclear explosion of a C+O white dwarf which, by accretion from a companion, approaches the Chandrasekhar mass. Whilst this scenario can account for most of the observed properties of SNe Ia, the exact nature of the explosion mechanism remains uncertain. This thesis presents the results obtained from hydrodynamical model calculations of post-explosion envelope expansion. The hydrodynamics are followed in spherical symmetry using a Lagrangean code, the energy equation being solved in the diffusion approximation. The conversion of decay gamma-rays into thermal energy is treated as an absorption process, while the time-dependent opacity is calculated as a function of composition, density, temperature and velocity gradient. The results of these models--light-curve shape, maximum luminosities, and expansion velocity profiles---are compared with the bolometric observational data (SN1981B, SN1972E and the composite light curve obtained by Leibundgut for 9 SNe Ia in Virgo) and current theoretical models of the explosion mechanism. Delayed detonation and deflagration models (Bravo 1990), adopting different C ignition densities, have been investigated. In all cases, the resulting light curve is in satisfactory agreement with observations. As the ignition density varies, the maximum of light remains nearly constant and the dispersion in the rates of decline of the light curve is compatible with observations. Moreover, variation in the ignition density readily accounts for the dispersion of 1000 km s^-1 in the observed expansion velocities. Delayed detonation models yield high kinetic energies, that result in (especially for the highest ignition densities) high expansion velocities, steep post-peak declines of the light curves and velocity distribution of intermediate-mass elements that are higher than that inferred from observations. Conversely, deflagration models provide less energetic explosions. However
Curved spiral antennas for underwater biological applications
NASA Astrophysics Data System (ADS)
Llamas, Ruben
We developed curved spiral antennas for use in underwater (freshwater) communications. Specifically, these antennas will be integrated in so-called mussel backpacks. Backpacks are compact electronics that incorporate sensors and a small radio that operate around 300 MHz. Researchers attach these backpacks in their freshwater mussel related research. The antennas must be small, lightweight, and form-fit the mussel. Additionally, since the mussel orientation is unknown, the antennas must have broad radiation patterns. Further, the electromagnetic environment changes significantly as the mussels burrow into the river bottom. Broadband antennas, such a spiral antennas, will perform better in this instance. While spiral antennas are well established, there has been little work on their performance in freshwater. Additionally, there has been some work on curved spiral antennas, but this work focused on curving in one dimension, namely curving around a cylinder. In this thesis we develop spiral antennas that curve in two dimensions in order to conform the contour of a mussel's shell. Our research has three components, namely (a) an investigation of the relevant theoretical underpinning of spiral antennas, (b) extensive computer simulations using state-of-the art computational electromagnetics (CEM) simulation software, and (c) experimental validation. The experimental validation was performed in a large tank in a laboratory setting. We also validated some designs in a pool (~300,000 liters of water and ~410 squared-meter dive pool) with the aid of a certified diver. To use CEM software and perform successful antenna-related experiments require careful attention to many details. The mathematical description of radiation from an antenna, antenna input impedance and so on, is inherently complex. Engineers often make simplifying assumptions such as assuming no reflections, or an isotropic propagation environment, or operation in the antenna far field, and so on. This makes
Christensen, S. W.; Goodyear, C. P.; Kirk, B. L.
1982-03-01
This report addresses the validity of the utilities' use of the Ricker stock-recruitment model to extrapolate the combined entrainment-impingement losses of young fish to reductions in the equilibrium population size of adult fish. In our testimony, a methodology was developed and applied to address a single fundamental question: if the Ricker model really did apply to the Hudson River striped bass population, could the utilities' estimates, based on curve-fitting, of the parameter alpha (which controls the impact) be considered reliable. In addition, an analysis is included of the efficacy of an alternative means of estimating alpha, termed the technique of prior estimation of beta (used by the utilities in a report prepared for regulatory hearings on the Cornwall Pumped Storage Project). This validation methodology should also be useful in evaluating inferences drawn in the literature from fits of stock-recruitment models to data obtained from other fish stocks.
Robust Entrainment of Circadian Oscillators Requires Specific Phase Response Curves
Pfeuty, Benjamin; Thommen, Quentin; Lefranc, Marc
2011-01-01
The circadian clocks keeping time in many living organisms rely on self-sustained biochemical oscillations entrained by external cues, such as light, to the 24-h cycle induced by Earth's rotation. However, environmental cues are unreliable due to the variability of habitats, weather conditions, or cue-sensing mechanisms among individuals. A tempting hypothesis is that circadian clocks have evolved so as to be robust to fluctuations in the signal that entrains them. To support this hypothesis, we analyze the synchronization behavior of weakly and periodically forced oscillators in terms of their phase response curve (PRC), which measures phase changes induced by a perturbation applied at different times of the cycle. We establish a general relationship between the robustness of key entrainment properties, such as stability and oscillator phase, on the one hand, and the shape of the PRC as characterized by a specific curvature or the existence of a dead zone, on the other hand. The criteria obtained are applied to computational models of circadian clocks and account for the disparate robustness properties of various forcing schemes. Finally, the analysis of PRCs measured experimentally in several organisms strongly suggests a case of convergent evolution toward an optimal strategy for maintaining a clock that is accurate and robust to environmental fluctuations. PMID:21641300
Research and optimization on stator curve for roller pump
NASA Astrophysics Data System (ADS)
Yang, G. L.; Zhang, J. F.; Su, H. S.; Zhang, L. Q.
2013-12-01
By analyzing the advantages and disadvantages of common roller pump's stator curve (assuming that the roller on this stator curve has eliminated the void point), using curve fitting transitional method to pass the soft and hard impact point, then we can obtain a high order stator curve which has lower noise. By creating a smooth stator curve (and an inflection point with a common tangent) radial velocity mutation is eliminated. In order to avoid radial velocity mutation a symmetrical radial acceleration curve is used. In order to eliminate radial acceleration mutation, both ends of the radial acceleration change rate curve are valued zero. The results showed that due to the catastrophe point of the roller's stator curve, improving its stator curve eliminates the void point and the soft and hard impact point of the roller on the stator transitional curve. Compare the eighth-power stator curve with the improved stator curve, the improved curve also has the same superior performance. On the improved stator curve, the flow pulsation could be decreased by 241.39mL/min, with which the abrasion of the roller, the impact of the pump and the noise of the pump can be reduced.
A variational characterization and geometric integration for Bertrand curves
NASA Astrophysics Data System (ADS)
Lucas, Pascual; Ortega-Yagües, José Antonio
2013-04-01
In this paper, we introduce a class of functionals, in the three-dimensional semi-Euclidean space {R}^3_q, having an energy density that depends only on curvature and whose moduli space of trajectories consists of LW-curves, i.e., curves with curvature κ and torsion τ for which there are three real constants λ, μ, ρ such that λκ + μτ = ρ, with λ2 + μ2 > 0. This family of curves includes plane curves, helices, curves of constant curvature, curves of constant torsion, Lancret curves (also called generalized helices), and Bertrand curves. We present an algorithm to construct Bertrand curves in {R}^3_q by using an arclength parametrized curve in a totally umbilical surface {S}^2, {S}^2_1, or {H}^2 and prove that every Bertrand curve in {R}^3_q can be obtained in this way. A second algorithm is presented for the construction of LW-curves by using a curve of constant slope in the ruled surface Sα whose directrix is a certain curve α with non-zero curvature and whose rulings are generated by its modified Darboux vector field.
Creating A Light Curve Using Gathered Data
NASA Astrophysics Data System (ADS)
Wiggs, Joseph; Stolarz, S. A.; DePorto, R. W.; Shake, W. J.; Piper, M.; Linder, T. R.; Holmes, R.; Conwell, J.
2012-01-01
Our group of students with the support of educators and astronomers carried out a program to do astrometric and photometric analysis on the asteroid 2000 SO1 with the objective of obtaining a more in depth analysis of this asteroid and publishing light curve data describing the period of the asteroid. We chose our target asteroid using the minor planet center database, choosing an object that would have an acceptable Right Ascension, Declination, magnitude, and air mass for the ARO (Astronomical Research Observatory)-30 inch telescope operated by the SKYNET program. Our journey began with using Astrometrica for the IASC/WISE Program to identify and find new asteroids in the sky and add data to the Minor Planet Center Database. We then used MPO (Minor Planet Observatory) Canopus to form a light curve and conduct a fourier analysis on an example asteroid to familiarize ourselves with the program and used the program again to conduct fourier analysis on asteroid 2000 SO1. The educational goal in mind was to (a) learn the process of collecting and analyzing data using Astrometrica, MPO Canopus, the Minor Planet Center, and SKYNET and (b) create a poster to display the steps used in the process of surveying taken images and the production of a light curve. We collected 300 images a night, while discarding all the corrupted images, until we had enough data to accurately represent the object.Our work was successful due to resources from; Eastern Illinois University's Physics Department, the Astronomical Research Observatory, the University of Chicago's Yerkes Observatory, the SKYNET network, NASA's IASC/WISE (International Astronomical Search Collaboration/ Wide-Field Infrared Survey Explorer), NITARP (NASA/IPAC Teacher Archive Research Program) and Lincoln-Way North High School.
ERIC Educational Resources Information Center
Carlson, Patricia
1993-01-01
Describes a three-week environmental minicourse in a general chemistry class. The minicourse consisted of two distinct phases, a one-week introduction to environmental chemistry and a two-week project involving a particular environmental problem. (PR)
Calibrating Curved Crystals Used for Plasma Spectroscopy
Haugh, M. J., Jacoby, K. D., Ross, P. W., Rochau, G. Wu, M., Regan, S. P., Barrios, M. A.
2012-10-29
The throughput and resolving power of an X-ray spectrometer that uses a curved crystal as the diffraction element is determined primarily by the crystal X-ray reflectivity properties. This poster presents a measurement technique for these crystal parameters using a simple diode source to produce a narrow spectral band. The results from measurements on concave elliptical polyethylene terephthalate (PET) crystals and convex potassium acid phthalate (KAP) crystals show large variations in the key parameters compared to those from the flat crystal.
Robotically assisted lobectomy: learning curve and complications.
Melfi, Franca M A; Mussi, Alfredo
2008-08-01
The past two decades have witnessed a revolutionary transition in surgical technique and technology with the development of minimally invasive approaches. Many advantages were obtained by using video-assisted thoracoscopic surgery: less surgical trauma and pain, shorter hospital stay, and satisfactory cosmetic results. Limitations still remain, however, because of impaired vision, restricted instrument-maneuverability, unstable camera platform, and poor ergonomics for the surgeon. Some of the more prominent limitations involve the technical and mechanical nature of the equipment. This article describes technical aspects, learning curve, and complications in the field of robotic lobectomy. PMID:18831505
Curve of Spee - from orthodontic perspective.
Dhiman, Sushma
2015-01-01
The presence of a curve of Spee (COS) of variable depth is common finding in the occlusal arrangement and is sixth key of occlusion The understanding of COS in the field of orthodontics is very important as orthodontists deal with it in virtually every patient they treat. An excessive COS is a common form of malocclusion that may be addressed in many ways, including posterior extrusion, anterior intrusion, and incisor proclination. The specific approach to leveling of COS should be selected based on each patient's needs. Soft tissue, crown-gingival relations, occlusal plane, and skeletofacial concerns are among the special considerations for treatment planning for leveling of COS. PMID:26752075
SPECTRA AND LIGHT CURVES OF FAILED SUPERNOVAE
Fryer, Chris L.; Dahl, Jon A.; Fontes, Christopher J. E-mail: dahl@lanl.go
2009-12-10
Astronomers have proposed a number of mechanisms to produce supernova explosions. Although many of these mechanisms are now not considered primary engines behind supernovae (SNe), they do produce transients that will be observed by upcoming ground-based surveys and NASA satellites. Here, we present the first radiation-hydrodynamics calculations of the spectra and light curves from three of these 'failed' SNe: SNe with considerable fallback, accretion-induced collapse of white dwarfs, and energetic helium flashes (also known as type Ia SNe).
Peranso - Light curve and period analysis software
NASA Astrophysics Data System (ADS)
Paunzen, E.; Vanmunster, T.
2016-03-01
A time series is a sample of observations of well-defined data points obtained through repeated measurements over a certain time range. The analysis of such data samples has become increasingly important not only in natural science but also in many other fields of research. Peranso offers a complete set of powerful light curve and period analysis functions to work with large astronomical data sets. Substantial attention has been given to ease-of-use and data accuracy, making it one of the most productive time series analysis software available. In this paper, we give an introduction to Peranso and its functionality.
Learning Curves in Arthroplasty in Orthopedic Trainees.
Nzeako, Obinna; Back, Diane
2016-01-01
The NHS is adapting to a changing environment, in which economical constraints have forced theatres to maximise efficiency. An environment in which working hours and surgical exposure has been reduced and outcomes are being published. Litigation is high, and patients are living longer with higher demands. We ask, will traditional methods of apprentiship type training suffice in producing competent arthroplasty surgeons when hands on experience is falling. We review learning curves and assessment tools available to accurately assess competency and support trainee orthopaedic surgeons in their acquisition of surgical proficiency. PMID:27168384
Invariant rotational curves in Sitnikov's Problem
NASA Astrophysics Data System (ADS)
Martinez Alfaro, J.; Chiralt, Cristina
1993-04-01
The Sitnikov's Problem is a restricted three-body problem of celestial mechanics depending on the eccentricity, e. The Hamiltonian, H(z, v, t, e), does not depend on t if e = 0 and we have an integrable system; if e is small the KAM Theory proves the existence of invariant rotational curves, IRC. For larger eccentricities, we show that there exist two complementary sequences of intervals of values of e that accumulate to the maximum admissible value of the eccentricity, 1, and such that, for one of the sequences IRC around a fixed point persist. Moreover, they shrink to the plane z = 0 as e tends to 1.
Relativistic electron in curved magnetic fields
NASA Technical Reports Server (NTRS)
An, S.
1985-01-01
Making use of the perturbation method based on the nonlinear differential equation theory, the author investigates the classical motion of a relativistic electron in a class of curved magnetic fields which may be written as B=B(O,B sub phi, O) in cylindrical coordinates (R. phi, Z). Under general astrophysical conditions the author derives the analytical expressions of the motion orbit, pitch angle, etc., of the electron in their dependence upon parameters characterizing the magnetic field and electron. The effects of non-zero curvature of magnetic field lines on the motion of electrons and applicabilities of these results to astrophysics are also discussed.
Template Reproduction of GRB Pulse Light Curves
NASA Astrophysics Data System (ADS)
Hakkila, Jon E.; Preece, R. D.; Loredo, T. J.; Wolpert, R. L.; Broadbent, M. E.
2014-01-01
A study of well-isolated pulses in gamma ray burst light curves indicates that simple models having smooth and monotonic pulse rises and decays are inadequate. Departures from the Norris et al. (2005) pulse shape are in the form of a wave-like pre-peak residual that is mirrored and stretched following the peak. Pulse shape departures are present in GRB pulses of all durations, but placement of the departures relative to pulse peaks correlates with asymmetry. This establishes an additional link between temporal structure and spectral evolution, as pulse asymmetry is related to initial hardness while pulse duration indicates the rate of hard-to-soft pulse evolution.
Curve of Spee - from orthodontic perspective
Dhiman, Sushma
2015-01-01
The presence of a curve of Spee (COS) of variable depth is common finding in the occlusal arrangement and is sixth key of occlusion The understanding of COS in the field of orthodontics is very important as orthodontists deal with it in virtually every patient they treat. An excessive COS is a common form of malocclusion that may be addressed in many ways, including posterior extrusion, anterior intrusion, and incisor proclination. The specific approach to leveling of COS should be selected based on each patient's needs. Soft tissue, crown–gingival relations, occlusal plane, and skeletofacial concerns are among the special considerations for treatment planning for leveling of COS. PMID:26752075
Enumeration of curves with one singular point
NASA Astrophysics Data System (ADS)
Basu, Somnath; Mukherjee, Ritwik
2016-06-01
In this paper we obtain an explicit formula for the number of curves in P2, of degree d, passing through (d(d + 3) / 2 - k) generic points and having a singularity X, where X is of type Ak≤7 ,Dk≤7 or Ek≤7. Our method comprises of expressing the enumerative problem as the Euler class of an appropriate bundle and using a purely topological method to compute the degenerate contribution to the Euler class. These numbers have also been computed by M. Kazarian using the existence of universal formulas for Thom polynomials.
Light-curve Analysis of Neon Novae
NASA Astrophysics Data System (ADS)
Hachisu, Izumi; Kato, Mariko
2016-01-01
We analyzed light curves of five neon novae, QU Vul, V351 Pup, V382 Vel, V693 CrA, and V1974 Cyg, and determined their white dwarf (WD) masses and distance moduli on the basis of theoretical light curves composed of free-free and photospheric emission. For QU Vul, we obtained a distance of d ˜ 2.4 kpc, reddening of E(B - V) ˜ 0.55, and WD mass of MWD = 0.82-0.96 {M}⊙ . This suggests that an oxygen-neon WD lost a mass of more than ˜ 0.1 {M}⊙ since its birth. For V351 Pup, we obtained d˜ 5.5 {{kpc}}, E(B-V)˜ 0.45, and {M}{{WD}}=0.98-1.1 {M}⊙ . For V382 Vel, we obtained d˜ 1.6 {{kpc}}, E(B-V)˜ 0.15, and {M}{{WD}}=1.13-1.28 {M}⊙ . For V693 CrA, we obtained d˜ 7.1 {{kpc}}, E(B-V)˜ 0.05, and {M}{{WD}}=1.15-1.25 {M}⊙ . For V1974 Cyg, we obtained d˜ 1.8 {{kpc}}, E(B-V)˜ 0.30, and {M}{{WD}}=0.95-1.1 {M}⊙ . For comparison, we added the carbon-oxygen nova V1668 Cyg to our analysis and obtained d˜ 5.4 {{kpc}}, E(B-V)˜ 0.30, and {M}{{WD}}=0.98-1.1 {M}⊙ . In QU Vul, photospheric emission contributes 0.4-0.8 mag at most to the optical light curve compared with free-free emission only. In V351 Pup and V1974 Cyg, photospheric emission contributes very little (0.2-0.4 mag at most) to the optical light curve. In V382 Vel and V693 CrA, free-free emission dominates the continuum spectra, and photospheric emission does not contribute to the optical magnitudes. We also discuss the maximum magnitude versus rate of decline relation for these novae based on the universal decline law.
Cracks in Sheets Draped on Curved Surfaces
NASA Astrophysics Data System (ADS)
Mitchell, Noah P.; Koning, Vinzenz; Vitelli, Vincenzo; Irvine, William T. M.
Conforming materials to surfaces with Gaussian curvature has proven a versatile tool to guide the behavior of mechanical defects such as folds, blisters, scars, and pleats. In this talk, we show how curvature can likewise be used to control material failure. In our experiments, thin elastic sheets are confined on curved geometries that stimulate or suppress the growth of cracks, and steer or arrest their propagation. By redistributing stresses in a sheet, curvature provides a geometric tool for protecting certain regions and guiding crack patterns. A simple model captures crack behavior at the onset of propagation, while a 2D phase-field model successfully captures the crack's full phenomenology.
A theory for turbulent curved wall jets
NASA Technical Reports Server (NTRS)
Roberts, Leonard
1986-01-01
A simple theoretical model is proposed to describe the flow of a turbulent wall jet along a curved surface into a quiescent atmosphere. An integral method is used to solve the momentum equation and identifies three contributions to the spreading rate of the wall jet: (1) turbulent diffusion in the wall jet; (2) wall curvature; and (3) rate of change of wall curvature. Closed from approximate solutions are found for the case of a plane wall, a circular cylinder, and a logarithmic spiral surface. Comparison with experimental data for these three cases is made showing good agreement.
Geostatistical prediction of flow-duration curves
NASA Astrophysics Data System (ADS)
Pugliese, A.; Castellarin, A.; Brath, A.
2013-11-01
We present in this study an adaptation of Topological kriging (or Top-kriging), which makes the geostatistical procedure capable of predicting flow-duration curves (FDCs) in ungauged catchments. Previous applications of Top-kriging mainly focused on the prediction of point streamflow indices (e.g. flood quantiles, low-flow indices, etc.). In this study Top-kriging is used to predict FDCs in ungauged sites as a weighted average of standardised empirical FDCs through the traditional linear-weighting scheme of kriging methods. Our study focuses on the prediction of period-of-record FDCs for 18 unregulated catchments located in Central Italy, for which daily streamflow series with length from 5 to 40 yr are available, together with information on climate referring to the same time-span of each daily streamflow sequence. Empirical FDCs are standardised by a reference streamflow value (i.e. mean annual flow, or mean annual precipitation times the catchment drainage area) and the overall deviation of the curves from this reference value is then used for expressing the hydrological similarity between catchments and for deriving the geostatistical weights. We performed an extensive leave-one-out cross-validation to quantify the accuracy of the proposed technique, and to compare it to traditional regionalisation models that were recently developed for the same study region. The cross-validation points out that Top-kriging is a reliable approach for predicting FDCs, which can significantly outperform traditional regional models in ungauged basins.
Coexistence Curve of Perfluoromethylcyclohexane-Isopropyl Alcohol
NASA Technical Reports Server (NTRS)
Jacobs, D. T.; Kuhl, D. E.; Selby, C. E.
1996-01-01
The coexistence curve of the binary fluid mixture perfluoromethylcyclohexane-isopropyl alcohol was determined by precisely measuring the refractive index both above and below its upper critical consolute point. Sixty-seven two-phase data points were obtained over a wide range of reduced temperatures, 10(exp -5) less than t less than 2.5 x 10(exp -1), to determine the location of the critical point: critical temperature=89.901 C, and critical composition = 62.2% by volume perfluoromethylcyclohexane. These data were analyzed to determine the critical exponent 8 close to the critical point, the amplitude B, and the anomaly in the diameter. The volume-fraction coexistence curve is found to be as symmetric as any composition like variable. Correction to scaling is investigated as well as the need for a crossover theory. A model is proposed that describes the asymptotic approach to zero of the effective exponent Beta, which allows an estimation of the temperature regime free of crossover effects.
Spherical nanoindentation stress–strain curves
Pathak, Siddhartha; Kalidindi, Surya R.
2015-03-24
Although indentation experiments have long been used to measure the hardness and Young's modulus, the utility of this technique in analyzing the complete elastic–plastic response of materials under contact loading has only been realized in the past few years – mostly due to recent advances in testing equipment and analysis protocols. This paper provides a timely review of the recent progress made in this respect in extracting meaningful indentation stress–strain curves from the raw datasets measured in instrumented spherical nanoindentation experiments. These indentation stress–strain curves have produced highly reliable estimates of the indentation modulus and the indentation yield strength inmore » the sample, as well as certain aspects of their post-yield behavior, and have been critically validated through numerical simulations using finite element models as well as direct in situ scanning electron microscopy (SEM) measurements on micro-pillars. Much of this recent progress was made possible through the introduction of a new measure of indentation strain and the development of new protocols to locate the effective zero-point of initial contact between the indenter and the sample in the measured datasets. As a result, this has led to an important key advance in this field where it is now possible to reliably identify and analyze the initial loading segment in the indentation experiments.« less
Bell-Curve Based Evolutionary Optimization Algorithm
NASA Technical Reports Server (NTRS)
Sobieszczanski-Sobieski, J.; Laba, K.; Kincaid, R.
1998-01-01
The paper presents an optimization algorithm that falls in the category of genetic, or evolutionary algorithms. While the bit exchange is the basis of most of the Genetic Algorithms (GA) in research and applications in America, some alternatives, also in the category of evolutionary algorithms, but use a direct, geometrical approach have gained popularity in Europe and Asia. The Bell-Curve Based Evolutionary Algorithm (BCB) is in this alternative category and is distinguished by the use of a combination of n-dimensional geometry and the normal distribution, the bell-curve, in the generation of the offspring. The tool for creating a child is a geometrical construct comprising a line connecting two parents and a weighted point on that line. The point that defines the child deviates from the weighted point in two directions: parallel and orthogonal to the connecting line, the deviation in each direction obeying a probabilistic distribution. Tests showed satisfactory performance of BCB. The principal advantage of BCB is its controllability via the normal distribution parameters and the geometrical construct variables.
Curved Piezoelectric Actuators for Stretching Optical Fibers
NASA Technical Reports Server (NTRS)
Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.
2008-01-01
Assemblies containing curved piezoceramic fiber composite actuators have been invented as means of stretching optical fibers by amounts that depend on applied drive voltages. Piezoceramic fiber composite actuators are conventionally manufactured as sheets or ribbons that are flat and flexible, but can be made curved to obtain load-carrying ability and displacement greater than those obtainable from the flat versions. In the primary embodiment of this invention, piezoceramic fibers are oriented parallel to the direction of longitudinal displacement of the actuators so that application of drive voltage causes the actuator to flatten, producing maximum motion. Actuator motion can be transmitted to the optical fiber by use of hinges and clamp blocks. In the original application of this invention, the optical fiber contains a Bragg grating and the purpose of the controlled stretching of the fiber is to tune the grating as part of a small, lightweight, mode-hop-free, rapidly tunable laser for demodulating strain in Bragg-grating strain-measurement optical fibers attached to structures. The invention could also be used to apply controllable tensile force or displacement to an object other than an optical fiber.
High speed curved position sensitive detector
Hendricks, Robert W.; Wilson, Jack W.
1989-01-01
A high speed curved position sensitive porportional counter detector for use in x-ray diffraction, the detection of 5-20 keV photons and the like. The detector employs a planar anode assembly of a plurality of parallel metallic wires. This anode assembly is supported between two cathode planes, with at least one of these cathode planes having a serpentine resistive path in the form of a meander having legs generally perpendicular to the anode wires. This meander is produced by special microelectronic fabrication techniques whereby the meander "wire" fans outwardly at the cathode ends to produce the curved aspect of the detector, and the legs of the meander are small in cross-section and very closely spaced whereby a spatial resolution of about 50 .mu.m can be achieved. All of the other performance characteristics are about as good or better than conventional position sensitive proportional counter type detectors. Count rates of up to 40,000 counts per second with 0.5 .mu.s shaping time constants are achieved.
Spherical nanoindentation stress–strain curves
Pathak, Siddhartha; Kalidindi, Surya R.
2015-03-24
Although indentation experiments have long been used to measure the hardness and Young's modulus, the utility of this technique in analyzing the complete elastic–plastic response of materials under contact loading has only been realized in the past few years – mostly due to recent advances in testing equipment and analysis protocols. This paper provides a timely review of the recent progress made in this respect in extracting meaningful indentation stress–strain curves from the raw datasets measured in instrumented spherical nanoindentation experiments. These indentation stress–strain curves have produced highly reliable estimates of the indentation modulus and the indentation yield strength in the sample, as well as certain aspects of their post-yield behavior, and have been critically validated through numerical simulations using finite element models as well as direct in situ scanning electron microscopy (SEM) measurements on micro-pillars. Much of this recent progress was made possible through the introduction of a new measure of indentation strain and the development of new protocols to locate the effective zero-point of initial contact between the indenter and the sample in the measured datasets. As a result, this has led to an important key advance in this field where it is now possible to reliably identify and analyze the initial loading segment in the indentation experiments.
NASA Astrophysics Data System (ADS)
Shrader, C. R.; Titarchuk, L.
2001-12-01
We describe recent work in which we revisit the database of historical X-Ray nova (XRN) light curves compiled by Chen, Shrader & Livio (1997, ApJ 491, 312), augmented by subsequent events recorded by RXTE, in an attempt to gain a better understanding of the outburst phenomenon. In this presentation, we demonstrate that, given the occurrence of an instability in the mass transfer rate from the secondary, a model based on viscous diffusion of matter through the disk (Wood et al, 2001, astro-ph/0108189) can reproduce a large number of fast-rise exponential decay (FRED) type XRN light curves. Deviations from the FRED form, such as plateaus and power-law decay forms are also considered within this framework. More complex structures are, in a number of instances, successfully modeled as a superposition of mass-injection, diffusive propagation events. Limitations to this approach are considered. For example, recent concerns regarding the ability of viscous diffusion scenarios to reproduce the typical XRN rise and time scales (e.g. Cannizzo, ApJ, astro-ph/0110117) are discussed, as are possible time-dependent viscosity effects.
Paschen Curve Observations at Liquid Nitrogen Temperatures
NASA Astrophysics Data System (ADS)
Dugger, Chip; Rielage, Keith; Elliott, Steven; Massarczyk, Ralph; Chu, Pinghan
2015-10-01
Paschen's Law states an equation giving the relationship between variables involved when forming an electrical arc between two conductive objects, otherwise known as the breakdown voltage. This equation for the breakdown voltage VB is as follows: VB =apd/ln (pd) + b where p is the pressure in Atmospheres (or Bar), d is the gap or distance between the two conductive objects, and both a and b are constants that depend on the composition of the gas. In our experiment, the Paschen curve for gases (such as nitrogen) at temperatures lower than -200 degrees Celsius will be measured. The Paschen curve for air at room temperature will also be measured in order to test and calibrate our system. The goal of this experiment is to test how accurately Paschen's Law can predict the breakdown voltage in these specific, cold conditions. This experiment is being performed to gather information for a possible future experiment, which might use high purity germanium (HPGe) detectors in a similar cold environment to search for neutrinoless double beta decay, a rare hypothesized process that may yield valuable insight into the fundamental properties of the neutrino. This work is being supported by the DOE through the LANL LDRD program. Charles ``Chip'' Dugger, Los Alamos National Laboratory and New Mexico Institute of Mining and Technology.
NASA Astrophysics Data System (ADS)
DuPuy, D. L.
1981-02-01
The light curve of the star HD 200925 is investigated based on an analysis of published photoelectric observations. A preliminary search of the data for periodicities using the Jurkevich period search method indicates a period of 0.267 days, although the observations reported by Bedolla and Pe a (1979) for the night of September 26-27, 1978 are systematically brighter by about 0.08 magnitudes than the other observations. A nonlinear least squares fit of the values of the period, approximate amplitude (0.4 magnitude) and phase angle of the periodicity (0.9 radian) derived to a sinusoid is shown to differ significantly from the data obtained on the nights of September 24-25, 25-26 and 27-28, 1978, although confirming the period of 0.2672 days. Data also suggest the presence of a secondary period of 0.36 days, which, however, may rather be due to the asymmetry of the observed light curve.
Accurate determination of characteristic relative permeability curves
NASA Astrophysics Data System (ADS)
Krause, Michael H.; Benson, Sally M.
2015-09-01
A recently developed technique to accurately characterize sub-core scale heterogeneity is applied to investigate the factors responsible for flowrate-dependent effective relative permeability curves measured on core samples in the laboratory. The dependency of laboratory measured relative permeability on flowrate has long been both supported and challenged by a number of investigators. Studies have shown that this apparent flowrate dependency is a result of both sub-core scale heterogeneity and outlet boundary effects. However this has only been demonstrated numerically for highly simplified models of porous media. In this paper, flowrate dependency of effective relative permeability is demonstrated using two rock cores, a Berea Sandstone and a heterogeneous sandstone from the Otway Basin Pilot Project in Australia. Numerical simulations of steady-state coreflooding experiments are conducted at a number of injection rates using a single set of input characteristic relative permeability curves. Effective relative permeability is then calculated from the simulation data using standard interpretation methods for calculating relative permeability from steady-state tests. Results show that simplified approaches may be used to determine flowrate-independent characteristic relative permeability provided flow rate is sufficiently high, and the core heterogeneity is relatively low. It is also shown that characteristic relative permeability can be determined at any typical flowrate, and even for geologically complex models, when using accurate three-dimensional models.
Spatially varying dispersion to model breakthrough curves.
Li, Guangquan
2011-01-01
Often the water flowing in a karst conduit is a combination of contaminated water entering at a sinkhole and cleaner water released from the limestone matrix. Transport processes in the conduit are controlled by advection, mixing (dilution and dispersion), and retention-release. In this article, a karst transport model considering advection, spatially varying dispersion, and dilution (from matrix seepage) is developed. Two approximate Green's functions are obtained using transformation of variables, respectively, for the initial-value problem and for the boundary-value problem. A numerical example illustrates that mixing associated with strong spatially varying conduit dispersion can cause strong skewness and long tailing in spring breakthrough curves. Comparison of the predicted breakthrough curve against that measured from a dye-tracing experiment between Ames Sink and Indian Spring, Northwest Florida, shows that the conduit dispersivity can be as large as 400 m. Such a large number is believed to imply strong solute interaction between the conduit and the matrix and/or multiple flow paths in a conduit network. It is concluded that Taylor dispersion is not dominant in transport in a karst conduit, and the complicated retention-release process between mobile- and immobile waters may be described by strong spatially varying conduit dispersion. PMID:21143474
Separation of magnetic susceptibility components from magnetization curves
NASA Astrophysics Data System (ADS)
Kosareva, L.; Nourgaliev, D.; Kuzina, D.; Spassov, S.; Fattakhov, A.
2014-12-01
Modern lake sediments are a unique source of information for climate changes, regionally and globally, because all environmental variations are recorded by these sediments with high resolution. The magnetic properties of Chernyshov Bay (Aral Sea) sediments we investigated from core number 4 (N45o57'04.2''; E59o17'14.3'') are taken at far water depth of 9.5 m. The length of the core is 4.16 m. Samples for measurements were taken to plastic sample boxes with internal dimensions 2x2x2 cm. Remanent magnetization curves were measured by coercivity spectrometer for the separate determination of the different contributions to the total bulk magnetic susceptibility. There was measured also magnetic susceptibility using MS2 susceptibility meter. Those operations were done for data comparison between 2 susceptibilities obtained from different equipment. Our goal is to decipher the magnetic susceptibility signal in lake sediments by decomposing the bulk susceptibility signal of a lake sediment sequence into ferromagnetic (χf), dia-/paramagnetic (χp) and superparamagnetic (χsp) components using data from remanent and indused magnetization curves Each of these component has a different origin: paramagnetic minerals are usually attributed to terrigenous sediment input, ferromagnetics are of biogenic origin, and superparamagnetic minerals may be of either biogenic or terrigenous origin. Comparison between susceptibility measurements of MS2-Bartington susceptometer and of the coercivity spectrometer has shown good correlation. The susceptibility values measured in two different equipment are fairly close and indicate thus the reliability the proposed method. In research also has shown water level changes in Aral Sea based on magnetic susceptibility. The work is performed according to the Russian Government Program of Competitive Growth of Kazan Federal University also by RFBR research projects No. 14-05-31376 - а, 14-05-00785- а.
Effects of LWR coolant environments on fatigue design curves of carbon and low-alloy steels
Chopra, O.K.; Shack, W.J.
1998-03-01
The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. Figures I-9.1 through I-9.6 of Appendix I to Section III of the code specify fatigue design curves for structural materials. While effects of reactor coolant environments are not explicitly addressed by the design curves, test data indicate that the Code fatigue curves may not always be adequate in coolant environments. This report summarizes work performed by Argonne National Laboratory on fatigue of carbon and low-alloy steels in light water reactor (LWR) environments. The existing fatigue S-N data have been evaluated to establish the effects of various material and loading variables such as steel type, dissolved oxygen level, strain range, strain rate, temperature, orientation, and sulfur content on the fatigue life of these steels. Statistical models have been developed for estimating the fatigue S-N curves as a function of material, loading, and environmental variables. The results have been used to estimate the probability of fatigue cracking of reactor components. The different methods for incorporating the effects of LWR coolant environments on the ASME Code fatigue design curves are presented.
Transport Sector Marginal Abatement Cost Curves in Computable General Equilibrium Model
NASA Astrophysics Data System (ADS)
Tippichai, Atit; Fukuda, Atsushi; Morisugi, Hisayoshi
In the last decade, computable general equilibrium (CGE) models have emerged a standard tool for climate policy evaluation due to their abilities to prospectively elucidate the character and magnitude of the economic impacts of energy and environmental policies. Furthermore, marginal abatement cost (MAC) curves which represent GHG emissions reduction potentials and costs can be derived from these top-down economic models. However, most studies have never address MAC curves for a specific sector that have a large coverage of countries which are needed for allocation of optimal emission reductions. This paper aims to explicitly describe the meaning and character of MAC curves for transport sector in a CGE context through using the AIM/CGE Model developed by Toshihiko Masui. It found that the MAC curves derived in this study are the inverse of the general equilibrium reduction function for CO2 emissions. Moreover, the transport sector MAC curves for six regions including USA, EU-15, Japan, China, India, and Brazil, derived from this study are compared to the reduction potentials under 100 USD/tCO2 in 2020 from a bottom-up study. The results showed that the ranking of the regional reduction potentials in transport sector from this study are almost same with the bottom-up study except the ranks of the EU-15 and China. In addition, the range of the reduction potentials from this study is wider and only the USA has higher potentials than those derived from the bottom-up study.
Mougabure-Cueto, G; Sfara, V
2016-04-25
Dose-response relations can be obtained from systems at any structural level of biological matter, from the molecular to the organismic level. There are two types of approaches for analyzing dose-response curves: a deterministic approach, based on the law of mass action, and a statistical approach, based on the assumed probabilities distribution of phenotypic characters. Models based on the law of mass action have been proposed to analyze dose-response relations across the entire range of biological systems. The purpose of this paper is to discuss the principles that determine the dose-response relations. Dose-response curves of simple systems are the result of chemical interactions between reacting molecules, and therefore are supported by the law of mass action. In consequence, the shape of these curves is perfectly sustained by physicochemical features. However, dose-response curves of bioassays with quantal response are not explained by the simple collision of molecules but by phenotypic variations among individuals and can be interpreted as individual tolerances. The expression of tolerance is the result of many genetic and environmental factors and thus can be considered a random variable. In consequence, the shape of its associated dose-response curve has no physicochemical bearings; instead, they are originated from random biological variations. Due to the randomness of tolerance there is no reason to use deterministic equations for its analysis; on the contrary, statistical models are the appropriate tools for analyzing these dose-response relations. PMID:26952004
van Stralen, Marijn; Chu, Winnie C. W.; Lam, Tsz-Ping; Ng, Bobby K. W.; Vincken, Koen L.; Cheng, Jack C. Y.; Castelein, René M.
2016-01-01
Introduction Although much attention has been given to the global three-dimensional aspect of adolescent idiopathic scoliosis (AIS), the accurate three-dimensional morphology of the primary and compensatory curves, as well as the intervening junctional segments, in the scoliotic spine has not been described before. Methods A unique series of 77 AIS patients with high-resolution CT scans of the spine, acquired for surgical planning purposes, were included and compared to 22 healthy controls. Non-idiopathic curves were excluded. Endplate segmentation and local longitudinal axis in endplate plane enabled semi-automatic geometric analysis of the complete three-dimensional morphology of the spine, taking inter-vertebral rotation, intra-vertebral torsion and coronal and sagittal tilt into account. Intraclass correlation coefficients for interobserver reliability were 0.98–1.00. Coronal deviation, axial rotation and the exact length discrepancies in the reconstructed sagittal plane, as defined per vertebra and disc, were analyzed for each primary and compensatory curve as well as for the junctional segments in-between. Results The anterior-posterior difference of spinal length, based on “true” anterior and posterior points on endplates, was +3.8% for thoracic and +9.4% for (thoraco)lumbar curves, while the junctional segments were almost straight. This differed significantly from control group thoracic kyphosis (-4.1%; P<0.001) and lumbar lordosis (+7.8%; P<0.001). For all primary as well as compensatory curves, we observed linear correlations between the coronal Cobb angle, axial rotation and the anterior-posterior length difference (r≥0.729 for thoracic curves; r≥0.485 for (thoraco)lumbar curves). Conclusions Excess anterior length of the spine in AIS has been described as a generalized growth disturbance, causing relative anterior spinal overgrowth. This study is the first to demonstrate that this anterior overgrowth is not a generalized phenomenon. It is
Using Dragon Curves To Learn about Length and Area.
ERIC Educational Resources Information Center
Smith, Lyle R.
1999-01-01
Utilizes dragon curves which are made with three tiles and can be used to create fascinating patterns to help students understand the concepts of length, area, and perimeter of regions as defined by dragon curves. (ASK)
Cortical Hemisphere Registration Via Large Deformation Diffeomorphic Metric Curve Mapping
Qiu, Anqi; Miller, Michael I.
2010-01-01
We present large deformation diffeomorphic metric curve mapping (LDDMM-Curve) for registering cortical hemispheres. We showed global cortical hemisphere matching and evaluated the mapping accuracy in five subregions of the cortex in fourteen MRI scans. PMID:18051058
Nonlinear bulging factor based on R-curve data
NASA Technical Reports Server (NTRS)
Jeong, David Y.; Tong, Pin
1994-01-01
In this paper, a nonlinear bulging factor is derived using a strain energy approach combined with dimensional analysis. The functional form of the bulging factor contains an empirical constant that is determined using R-curve data from unstiffened flat and curved panel tests. The determination of this empirical constant is based on the assumption that the R-curve is the same for both flat and curved panels.
Curved centerline air intake for a gas turbine engine
NASA Technical Reports Server (NTRS)
Ruehr, W. C.; Younghans, J. L.; Smith, E. B. (Inventor)
1980-01-01
An inlet for a gas turbine engine was disposed about a curved centerline for the purpose of accepting intake air that is flowing at an angle to engine centerline and progressively turning that intake airflow along a curved path into alignment with the engine. This curved inlet is intended for use in under the wing locations and similar regions where airflow direction is altered by aerodynamic characteristics of the airplane. By curving the inlet, aerodynamic loss and acoustic generation and emission are decreased.
Majumdar, S.; Chopra, O.K.; Shack, W.J.
1993-01-01
Both temperature and oxygen affect fatigue life; at the very low dissolved-oxygen levels in PWRs and BWRs with hydrogen water chemistry, environmental effects on fatigue life are modest at all temperatures (T) and strain rates. Between 0.1 and 0.2 ppM, the effect of dissolved-oxygen increases rapidly. In oxygenated environments, fatigue life depends strongly on strain rate and T. A fracture mechanics model is developed for predicting fatigue lives, and interim environmentally assisted cracking (EAC)-adjusted fatigue curves are proposed for carbon steels, low-alloy steels, and austenitic stainless steels.
ERIC Educational Resources Information Center
Bandhu, Desh, Ed.
The Indian Environmental Society, in association with the International Programme on Environmental Management Education, organized two seminars on World Environment Day and Environmental Impact Assessment during June 1980. A large number of papers on various aspects of environmental management were presented during the seminars. The papers…
The +Gz recovery of consciousness curve
2014-01-01
Background The limiting physiological envelope to extreme gravitational stress is defined by neurologic symptoms and signs that result from exceeding neurologic tolerance. The edge of the limiting envelope is defined by the complete incapacitation associated with acceleration (+Gz) induced loss of consciousness. Should + Gz-induced loss of consciousness occur in-flight, brisk recovery of conscious function is essential for aircraft recovery. If recovery does not occur, accident investigation aimed at preventing such accidents is enhanced by understanding the temporal aspects of the resulting incapacitation. The mechanistic basis of neurological reintegration leading to consciousness recovery is of broad medical and scientific interest. Methods Recovery of consciousness episodes from a prospectively developed +Gz-induced loss of consciousness repository of healthy individuals was analyzed to define variables influencing recovery of consciousness. The time from loss to recovery of consciousness as measured by observable signs, is defined as the absolute incapacitation period. The absolute incapacitation period from 760 episodes of loss and recovery of consciousness in healthy humans was analyzed to define +Gz-profile variables that determine the duration of functional neurologic compromise. Results Mean time from loss to return of consciousness for 760 episodes of consciousness recovery was 10.4 ± 5.1 s; minimum 1 s; maximum 38 s. Offset rate for the +Gz-exposure deceleration profiles varied from a minimum of 0.17 Gs−1 to a maximum of 7.93 Gs−1.The curve produced by plotting +Gz-offset rate (Gs−1; y) versus absolute incapacitation period (s; x) described a hyperbolic relationship. The hyperbolic relationship indicates there is a minimum time (mean 8.29 ± 3.84 s) required for recovery of consciousness when complete loss of consciousness occurs. Conclusions Mean recovery time from +Gz-induced unconsciousness is dependent on the deceleration profile's offset
Thermonuclear supernova light curves: Progenitors and cosmology
NASA Astrophysics Data System (ADS)
Rodney, Steven A.
Thermonuclear Supernovae (TN SNe) are an extremely important tool in modern astronomy. In their role as cosmological distance probes, they have revealed the accelerated expansion of the universe and have begun to constrain the nature of the dark energy that may be driving that expansion. The next decade will see a succession of wide-field surveys producing thousands of TNSN detections each year. Traditional methods of SN analysis, rooted in time-intensive spectroscopic follow-up, will become completely impractical. To realize the potential of this coming tide of massive data sets, we will need to extract cosmographic parameters (redshift and luminosity distance) from SN photometry without any spectroscopic support. In this dissertation, I present the Supernova Ontology with Fuzzy Templates (SOFT) method, an innovative new approach to the analysis of SN light curves. SOFT uses the framework of fuzzy set theory to perform direct comparisons of SN candidates against template light curves, simultaneously producing both classifications and cosmological parameter estimates. The SOFT method allows us to shed new light on two rich archival data sets. I revisit the IfA Deep Survey and HST GOODS to extract new and improved measurements of the TNSN rate from z=0.2 out to z=1.6. Our new analysis shows a steady increase in the TNSN rate out to z˜1, and adds support for a decrease in the rate at z=1.5. Comparing these rate measurements to theoretical models, I conclude that the progenitor scenario most favored by the collective observational data is a single degenerate model, regulated by a strong wind from the accreting white dwarf. Using a compilation of SN light curves from five recent surveys, I demonstrate that SOFT is able to derive useful constraints on cosmological models from a data set with no spectroscopic information at all. Looking ahead to the near future, I find that photometric analysis of data sets containing 2,000 SNe will be able to improve our constraints on
Clement, Matthieu; Meunie, Andre
2010-01-01
The object of this article is to examine the relation between social inequalities and pollution. First of all we provide a survey demonstrating that, from a theoretical point of view, a decrease in inequality has an uncertain impact on the environment. Second, on the basis of these conceptual considerations, we propose an econometric analysis based on panel data (fixed-effects and dynamic panel data models) concerning developing and transition countries for the 1988-2003 period. We examine specifically the effect of inequality on the extent of local pollution (sulphur dioxide emissions and organic water pollution) by integrating the Gini index into the formulation of the environmental Kuznets' curve. PMID:21280382
NASA Astrophysics Data System (ADS)
Bekhet,
2013-06-01
The present study examines an Environmental Kuznets Curve (EKC) hypothesis by analyzing annual data of air pollutants concentartion and per capita GDP as economic indicator over the (1996-2010) period in Malaysia. Nemerow Index Approach (I) used to generate a measures of air pollution. The results show that ambient air quality indicators supports the EKC hypothesis which stated that pollution levels increase as a country develops, but begin to decrease as rising incomes pass beyond a turning poin. Also, the I result is justifying that most pollutants are showing value less than 1.
Breakup of an invariant curve in a dissipative standard mapping
NASA Astrophysics Data System (ADS)
Yamaguchi, Yoshihiro
1986-06-01
A critical value for the existence of an invariant curve in a dissipative standard mapping is calculated by a new method in relation to Arnold's tongue. It is shown that the golden mean invariant curve is not the last curve for the strongly dissipative parameter region.
49 CFR 213.329 - Curves, elevation and speed limitations.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 49 Transportation 4 2012-10-01 2012-10-01 false Curves, elevation and speed limitations. 213.329... Higher § 213.329 Curves, elevation and speed limitations. (a) The maximum crosslevel on the outside rail... lower than the inside rail. (b) (1) The maximum allowable operating speed for each curve is...
Retiring the Short-Run Aggregate Supply Curve
ERIC Educational Resources Information Center
Elwood, S. Kirk
2010-01-01
The author argues that the aggregate demand/aggregate supply (AD/AS) model is significantly improved--although certainly not perfected--by trimming it of the short-run aggregate supply (SRAS) curve. Problems with the SRAS curve are shown first for the AD/AS model that casts the AD curve as identifying the equilibrium level of output associated…
Diversions: Hilbert and Sierpinski Space-Filling Curves, and beyond
ERIC Educational Resources Information Center
Gough, John
2012-01-01
Space-filling curves are related to fractals, in that they have self-similar patterns. Such space-filling curves were originally developed as conceptual mathematical "monsters", counter-examples to Weierstrassian and Reimannian treatments of calculus and continuity. These were curves that were everywhere-connected but nowhere-differentiable (or…
Spider diffraction: a comparison of curved and straight legs
Richter, J.L.
1984-06-15
It has been known for some time that, if curved legs rather than the usual straight ones are used in the spider that supports the secondary optics in certain telescopes, the visible diffraction effect is reduced. Fraunhofer theory is used to calculate the diffraction effects due to the curved leg spider. Calculated and photographic diffraction patterns are compared for straight and curved leg spiders.
On the convergence of planar curves under smoothing.
Zhong, Baojiang; Ma, Kai-Kuang
2010-08-01
Curve smoothing has two important applications in computer vision and image processing: 1) the curvature scale-space (CSS) technique for shape analysis, and 2) the Gaussian filter for noise suppression. In this paper, we study how planar curves converge as they are smoothed with increasing scales. First, two types of convergence behavior are clarified. The coined term shrinkage refers to the reduction of arc-length of a smoothed planar curve, which describes the convergence of the curve latitudinally; and another coined term collapse refers to the movement of each point to its limiting position, which describes the convergence of the curve longitudinally. A systematic study on the shrinkage and collapse of three categories of curve models is then presented. The corner models helps to reveal how the local structures of planar curves collapse and what the smoothed curves may converge to. The sawtooth models allows us to gain insights regarding how noise is suppressed from noisy planar curves by the Gaussian filter. Our investigation on the closed curves shows that each curve collapses to a point at its center of mass. However, different curves may yield different limiting shapes at the infinity scale. Finally, based upon the derived results the performance of the CSS technique in corner detection and shape representation is analyzed, and a fast implementation method of the Gaussian filter for noise suppression is proposed. PMID:20350854
Creative Tiling: A Story of 1000-and-1 Curves
ERIC Educational Resources Information Center
Al-Darwish, Nasir
2012-01-01
We describe a procedure that utilizes symmetric curves for building artistic tiles. One particular curve was found to mesh nicely with hundreds other curves, resulting in eye-catching tiling designs. The results of our work serve as a good example of using ideas from 2-D graphics and algorithms in a practical web-based application.
49 CFR 213.329 - Curves, elevation and speed limitations.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 49 Transportation 4 2011-10-01 2011-10-01 false Curves, elevation and speed limitations. 213.329... Higher § 213.329 Curves, elevation and speed limitations. (a) The maximum crosslevel on the outside rail... lower than the inside rail. (b) (1) The maximum allowable operating speed for each curve is...
49 CFR 213.57 - Curves; elevation and speed limitations.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 49 Transportation 4 2011-10-01 2011-10-01 false Curves; elevation and speed limitations. 213.57... speed limitations. (a) The maximum crosslevel on the outside rail of a curve may not be more than 8... applicable September 21, 1999.) (b)(1) The maximum allowable operating speed for each curve is determined...
49 CFR 213.57 - Curves; elevation and speed limitations.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Curves; elevation and speed limitations. 213.57... speed limitations. (a) The maximum crosslevel on the outside rail of a curve may not be more than 8... applicable September 21, 1999.) (b)(1) The maximum allowable operating speed for each curve is determined...
49 CFR 213.329 - Curves, elevation and speed limitations.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Curves, elevation and speed limitations. 213.329... Higher § 213.329 Curves, elevation and speed limitations. (a) The maximum crosslevel on the outside rail... lower than the inside rail. (b) (1) The maximum allowable operating speed for each curve is...
This study presents a method to predict flow duration curves (FDCs) and streamflow for ungauged catchments in the Mid-Atlantic Region, USA. We selected 29 catchments from the Appalachian Plateau, Ridge and Valley, and Piedmont physiographic provinces to develop and test the propo...
Section curve reconstruction and mean-camber curve extraction of a point-sampled blade surface.
Li, Wen-long; Xie, He; Li, Qi-dong; Zhou, Li-ping; Yin, Zhou-ping
2014-01-01
The blade is one of the most critical parts of an aviation engine, and a small change in the blade geometry may significantly affect the dynamics performance of the aviation engine. Rapid advancements in 3D scanning techniques have enabled the inspection of the blade shape using a dense and accurate point cloud. This paper proposes a new method to achieving two common tasks in blade inspection: section curve reconstruction and mean-camber curve extraction with the representation of a point cloud. The mathematical morphology is expanded and applied to restrain the effect of the measuring defects and generate an ordered sequence of 2D measured points in the section plane. Then, the energy and distance are minimized to iteratively smoothen the measured points, approximate the section curve and extract the mean-camber curve. In addition, a turbine blade is machined and scanned to observe the curvature variation, energy variation and approximation error, which demonstrates the availability of the proposed method. The proposed method is simple to implement and can be applied in aviation casting-blade finish inspection, large forging-blade allowance inspection and visual-guided robot grinding localization. PMID:25551467
Section Curve Reconstruction and Mean-Camber Curve Extraction of a Point-Sampled Blade Surface
Li, Wen-long; Xie, He; Li, Qi-dong; Zhou, Li-ping; Yin, Zhou-ping
2014-01-01
The blade is one of the most critical parts of an aviation engine, and a small change in the blade geometry may significantly affect the dynamics performance of the aviation engine. Rapid advancements in 3D scanning techniques have enabled the inspection of the blade shape using a dense and accurate point cloud. This paper proposes a new method to achieving two common tasks in blade inspection: section curve reconstruction and mean-camber curve extraction with the representation of a point cloud. The mathematical morphology is expanded and applied to restrain the effect of the measuring defects and generate an ordered sequence of 2D measured points in the section plane. Then, the energy and distance are minimized to iteratively smoothen the measured points, approximate the section curve and extract the mean-camber curve. In addition, a turbine blade is machined and scanned to observe the curvature variation, energy variation and approximation error, which demonstrates the availability of the proposed method. The proposed method is simple to implement and can be applied in aviation casting-blade finish inspection, large forging-blade allowance inspection and visual-guided robot grinding localization. PMID:25551467
Curved spacetimes and curved graphene: A status report of the Weyl symmetry approach
NASA Astrophysics Data System (ADS)
Iorio, Alfredo
2015-02-01
This is a status report about the ongoing work on the realization of quantum field theory on curved graphene spacetimes that uses Weyl symmetry. The programme is actively pursued from many different perspectives. Here we point to what has been done, and to what needs to be done.
Results from a Bragg curve spectrometer
NASA Astrophysics Data System (ADS)
Leach, D. D.; Davis, K. J.
The Bragg Curve Spectrometer (BCS) is an ionization chamber long enough to stop particles of interest. Particles enter through the cathode window and leave an ionization track parallel to the electric field. The ionization electrons drift through a Frisch grid and are collected on an anode. The anode current, as a function of time, is split and used as input for two amplifiers, one with a long integration time constant for energy measurement, and one with a short time constant to pick off the maximum ionization or Bragg peak. The Bragg peak, which is proportional to the nuclear charge, is used for particle identification. Several versions of the BCS have been constructed and tested. The results are described.
Dirac equation on a curved surface
NASA Astrophysics Data System (ADS)
Brandt, F. T.; Sánchez-Monroy, J. A.
2016-09-01
The dynamics of Dirac particles confined to a curved surface is examined employing the thin-layer method. We perform a perturbative expansion to first-order and split the Dirac field into normal and tangential components to the surface. In contrast to the known behavior of second order equations like Schrödinger, Maxwell and Klein-Gordon, we find that there is no geometric potential for the Dirac equation on a surface. This implies that the non-relativistic limit does not commute with the thin-layer method. Although this problem can be overcome when second-order terms are retained in the perturbative expansion, this would preclude the decoupling of the normal and tangential degrees of freedom. Therefore, we propose to introduce a first-order term which rescues the non-relativistic limit and also clarifies the effect of the intrinsic and extrinsic curvatures on the dynamics of the Dirac particles.
Light Curve of Minor Planet 1026 Ingrid
NASA Astrophysics Data System (ADS)
Delos, S.; Ahrendts, G.; Barker, T.
2012-06-01
(Abstract only) We have imaged minor planet 1026 Ingrid over the time period of July 29, 2011, to late September 2011, using the Wheaton College 0.25m telescope at Grove Creek Observatory in Australia via internet access. This telescope is equipped with a Santa Barbara Instrument Group STL-1001E CCD Camera, used with a clear filter. Over 1,000 30-second images were obtained and imported into the MPO Canopus software package for light curve analysis. Our preliminary estimate of the rotation period of 1026 Ingrid is 5.390 ± 0.001 hours, which is consistent with the previous estimate of 5.3 ± 0.3 hours (Székely, P., et al. 2005, Planet. Space Sci., 53, 925).
Curved VPH gratings for novel spectrographs
NASA Astrophysics Data System (ADS)
Clemens, J. Christopher; O'Donoghue, Darragh; Dunlap, Bart H.
2014-07-01
The introduction of volume phase holographic (VPH) gratings into astronomy over a decade ago opened new possibilities for instrument designers. In this paper we describe an extension of VPH grating technology that will have applications in astronomy and beyond: curved VPH gratings. These devices can disperse light while simultaneously correcting aberrations. We have designed and manufactured two different kinds of convex VPH grating prototypes for use in off-axis reflecting spectrographs. One type functions in transmission and the other in reflection, enabling Offnerstyle spectrographs with the high-efficiency and low-cost advantages of VPH gratings. We will discuss the design process and the tools required for modelling these gratings along with the recording layout and process steps required to fabricate them. We will present performance data for the first convex VPH grating produced for an astronomical spectrograph.
Bending the Cost Curve in Childhood Cancer.
Russell, Heidi; Bernhardt, M Brooke
2016-08-01
Healthcare for children with cancer costs significantly more than other children. Cost reduction efforts aimed toward relatively small populations of patients that use a disproportionate amount of care, like childhood cancer, could have a dramatic impact on healthcare spending. The aims of this review are to provide stakeholders with an overview of the drivers of financial costs of childhood cancer and to identify possible directions to curb or decrease these costs. Costs are incurred throughout the spectrum of care. Recent trends in pharmaceutical costs, evidence identifying the contribution of administration costs, and overuse of surveillance studies are described. Awareness of cost and value, i.e., the outcome achieved per dollar or burden spent, in delivery of care and research is necessary to bend the cost curve. Incorporation of these dimensions of care requires methodology development, prioritization, and ethical balance. PMID:27193602
Curved laser microjet in near field.
Kotlyar, Victor V; Stafeev, Sergey S; Kovalev, Alexey A
2013-06-20
With the use of the finite-difference time-domain-based simulation and a scanning near-field optical microscope that has a metal cantilever tip, the diffraction of a linearly polarized plane wave of wavelength λ by a glass corner step of height 2λ is shown to generate a low divergence laser jet of a root-parabolic form: over a distance of 4.7λ on the optical axis, the beam path is shifted by 2.1λ. The curved laser jet of the FWHM length depth of focus=9.5λ has the diameter FWHM=1.94λ over the distance 5.5λ, and the intensity maximum is 5 times higher than the incident wave intensity. The discrepancy between the analytical and the experimental results amounts to 11%. PMID:23842153
A flight evaluation of curved landing approaches
NASA Technical Reports Server (NTRS)
Gee, S. W.; Barber, M. R.; Mcmurtry, T. C.
1972-01-01
The development of STOL technology for application to operational short-haul aircraft is accompanied by the requirement for solving problems in many areas. One of the most obvious problems is STOL aircraft operations in the terminal area. The increased number of terminal operations needed for an economically viable STOL system as compared with the current CTOL system and the incompatibility of STOL and CTOL aircraft speeds are positive indicators of an imminent problem. The high cost of aircraft operations, noise pollution, and poor short-haul service are areas that need improvement. A potential solution to some of the operational problems lies in the capability of making curved landing approaches under both visual and instrument flight conditions.
Predicting unknown species numbers using discovery curves
Bebber, Daniel P; Marriott, Francis H.C; Gaston, Kevin J; Harris, Stephen A; Scotland, Robert W
2007-01-01
A common approach to estimating the total number of extant species in a taxonomic group is to extrapolate from the temporal pattern of known species descriptions. A formal statistical approach to this problem is provided. The approach is applied to a number of global datasets for birds, ants, mosses, lycophytes, monilophytes (ferns and horsetails), gymnosperms and also to New World grasses and UK flowering plants. Overall, our results suggest that unless the inventory of a group is nearly complete, estimating the total number of species is associated with very large margins of error. The strong influence of unpredictable variations in the discovery process on species accumulation curves makes these data unreliable in estimating total species numbers. PMID:17456460
Infrared camera based on a curved retina.
Dumas, Delphine; Fendler, Manuel; Berger, Frédéric; Cloix, Baptiste; Pornin, Cyrille; Baier, Nicolas; Druart, Guillaume; Primot, Jérôme; le Coarer, Etienne
2012-02-15
Design of miniature and light cameras requires an optical design breakthrough to achieve good optical performance. Solutions inspired by animals' eyes are the most promising. The curvature of the retina offers several advantages, such as uniform intensity and no field curvature, but this feature is not used. The work presented here is a solution to spherically bend monolithic IR detectors. Compared to state-of-the-art methods, a higher fill factor is obtained and the device fabrication process is not modified. We made an IR eye camera with a single lens and a curved IR bolometer. Images captured are well resolved and have good contrast, and the modulation transfer function shows better quality when comparing with planar systems. PMID:22344137
Curved Casimir Operators and the BGG Machinery
NASA Astrophysics Data System (ADS)
Cap, Andreas; Soucek, Vladimír
2007-11-01
We prove that the Casimir operator acting on sections of a homogeneous vector bundle over a generalized flag manifold naturally extends to an invariant differential operator on arbitrary parabolic geometries. We study some properties of the resulting invariant operators and compute their action on various special types of natural bundles. As a first application, we give a very general construction of splitting operators for parabolic geometries. Then we discuss the curved Casimir operators on differential forms with values in a tractor bundle, which nicely relates to the machinery of BGG sequences. This also gives a nice interpretation of the resolution of a finite dimensional representation by (spaces of smooth vectors in) principal series representations provided by a BGG sequence.
Titania single crystals with a curved surface.
Yang, Shuang; Yang, Bing Xing; Wu, Long; Li, Yu Hang; Liu, Porun; Zhao, Huijun; Yu, Yan Yan; Gong, Xue Qing; Yang, Hua Gui
2014-01-01
Owing to its scientific and technological importance, crystallization as a ubiquitous phenomenon has been widely studied over centuries. Well-developed single crystals are generally enclosed by regular flat facets spontaneously to form polyhedral morphologies because of the well-known self-confinement principle for crystal growth. However, in nature, complex single crystalline calcitic skeleton of biological organisms generally has a curved external surface formed by specific interactions between organic moieties and biocompatible minerals. Here we show a new class of crystal surface of TiO₂, which is enclosed by quasi continuous high-index microfacets and thus has a unique truncated biconic morphology. Such single crystals may open a new direction for crystal growth study since, in principle, crystal growth rates of all facets between two normal {101} and {011} crystal surfaces are almost identical. In other words, the facet with continuous Miller index can exist because of the continuous curvature on the crystal surface. PMID:25373513
Microorganism billiards in closed plane curves
NASA Astrophysics Data System (ADS)
Krieger, Madison
Recent experiments and numerical simulations have demonstrated that many species of microorganisms reflect aspecularly from a solid surface -- due to steric and hydrodynamic interactions with the wall, their outgoing angle is fixed and independent of the angle of incidence. Motivated by these results, we discuss theory and computation of the ``aspecular billiard'', a modification of the classical billiard in which the outgoing angle is constant. We restrict our attention to closed plane curves, focusing on three canonical examples: the ellipse, the Bunimovich stadium, and the Sinai billiard. These systems can have a rich array of orbits, and the Lyapunov exponent is shown to be dependent on the billiard geometry and the outgoing angle. We apply these results to the design of tunable passive sorting mechanisms.
Presheaves of Superselection Structures in Curved Spacetimes
NASA Astrophysics Data System (ADS)
Vasselli, Ezio
2015-04-01
We show that superselection structures on curved spacetimes that are expected to describe quantum charges affected by the underlying geometry are categories of sections of presheaves of symmetric tensor categories. When an embedding functor is given, the superselection structure is a Tannaka-type dual of a locally constant group bundle, which hence becomes a natural candidate for the role of the gauge group. Indeed, we show that any locally constant group bundle (with suitable structure group) acts on a net of C* algebras fulfilling normal commutation relations on an arbitrary spacetime. We also give examples of gerbes of C* algebras, defined by Wightman fields and constructed using projective representations of the fundamental group of the spacetime, which we propose as solutions for the problem that existence and uniqueness of the embedding functor are not guaranteed.
Quantum fields on closed timelike curves
Pienaar, J. L.; Myers, C. R.; Ralph, T. C.
2011-12-15
Recently, there has been much interest in the evolution of quantum particles on closed timelike curves (CTCs). However, such models typically assume pointlike particles with only two degrees of freedom; a very questionable assumption given the relativistic setting of the problem. We show that it is possible to generalize the Deutsch model of CTCs to fields using the equivalent circuit formalism. We give examples for coherent, squeezed, and single-photon states interacting with the CTC via a beamsplitter. The model is then generalized further to account for the smooth transition to normal quantum mechanics as the CTC becomes much smaller than the size of the modes interacting on it. In this limit, we find that the system behaves like a standard quantum-mechanical feedback loop.
Titania single crystals with a curved surface
NASA Astrophysics Data System (ADS)
Yang, Shuang; Yang, Bing Xing; Wu, Long; Li, Yu Hang; Liu, Porun; Zhao, Huijun; Yu, Yan Yan; Gong, Xue Qing; Yang, Hua Gui
2014-11-01
Owing to its scientific and technological importance, crystallization as a ubiquitous phenomenon has been widely studied over centuries. Well-developed single crystals are generally enclosed by regular flat facets spontaneously to form polyhedral morphologies because of the well-known self-confinement principle for crystal growth. However, in nature, complex single crystalline calcitic skeleton of biological organisms generally has a curved external surface formed by specific interactions between organic moieties and biocompatible minerals. Here we show a new class of crystal surface of TiO2, which is enclosed by quasi continuous high-index microfacets and thus has a unique truncated biconic morphology. Such single crystals may open a new direction for crystal growth study since, in principle, crystal growth rates of all facets between two normal {101} and {011} crystal surfaces are almost identical. In other words, the facet with continuous Miller index can exist because of the continuous curvature on the crystal surface.
Supernova Light Curves Powered by Fallback Accretion
NASA Astrophysics Data System (ADS)
Dexter, Jason; Kasen, Daniel
2013-07-01
Some fraction of the material ejected in a core collapse supernova explosion may remain bound to the compact remnant, and eventually turn around and fall back. We show that the late time (gsimdays) power potentially associated with the accretion of this "fallback" material could significantly affect the optical light curve, in some cases producing super-luminous or otherwise peculiar supernovae. We use spherically symmetric hydrodynamical models to estimate the accretion rate at late times for a range of progenitor masses and radii and explosion energies. The accretion rate onto the proto-neutron star or black hole decreases as \\dot{M} \\propto t^{-5/3} at late times, but its normalization can be significantly enhanced at low explosion energies, in very massive stars, or if a strong reverse shock wave forms at the helium/hydrogen interface in the progenitor. If the resulting super-Eddington accretion drives an outflow which thermalizes in the outgoing ejecta, the supernova debris will be re-energized at a time when photons can diffuse out efficiently. The resulting light curves are different and more diverse than previous fallback supernova models which ignored the input of accretion power and produced short-lived, dim transients. The possible outcomes when fallback accretion power is significant include super-luminous (gsim 1044 erg s-1) Type II events of both short and long durations, as well as luminous Type I events from compact stars that may have experienced significant mass loss. Accretion power may unbind the remaining infalling material, causing a sudden decrease in the brightness of some long duration Type II events. This scenario may be relevant for explaining some of the recently discovered classes of peculiar and rare supernovae.
Propagation of a curved weak shock
NASA Astrophysics Data System (ADS)
Monica, A.; Prasad, Phoolan
2001-05-01
Propagation of a curved shock is governed by a system of shock ray equations which is coupled to an infinite system of transport equations along these rays. For a two-dimensional weak shock, it has been suggested that this system can be approximated by a hyperbolic system of four partial differential equations in a ray coordinate system, which consists of two independent variables ([zeta], t) where the curves t = constant give successive positions of the shock and [zeta] = constant give rays. The equations show that shock rays not only stretch longitudinally due to finite amplitude on a shock front but also turn due to a non-uniform distribution of the shock strength on it. These changes finally lead to a modification of the amplitude of the shock strength. Since discontinuities in the form of kinks appear on the shock, it is necessary to study the problem by using the correct conservation form of these equations. We use such a system of equations in conservation form to construct a total-variation-bounded finite difference scheme. The numerical solution captures converging shock fronts with a pair of kinks on them the shock front emerges without the usual folds in the caustic region. The shock strength, even when the shock passes through the caustic region, remains so small that the small-amplitude theory remains valid. The shock strength ultimately decays with a well-defined geometrical shape of the shock front a pair of kinks which separate a central disc from a pair of wings on the two sides. We also study the ultimate shape and decay of shocks of initially periodic shapes and plane shocks with a dent and a bulge.
Dissipative dark matter explains rotation curves
NASA Astrophysics Data System (ADS)
Foot, R.
2015-06-01
Dissipative dark matter, where dark matter particles interact with a massless (or very light) boson, is studied. Such dark matter can arise in simple hidden sector gauge models, including those featuring an unbroken U (1 )' gauge symmetry, leading to a dark photon. Previous work has shown that such models can not only explain the large scale structure and cosmic microwave background, but potentially also dark matter phenomena on small scales, such as the inferred cored structure of dark matter halos. In this picture, dark matter halos of disk galaxies not only cool via dissipative interactions but are also heated via ordinary supernovae (facilitated by an assumed photon-dark photon kinetic mixing interaction). This interaction between the dark matter halo and ordinary baryons, a very special feature of these types of models, plays a critical role in governing the physical properties of the dark matter halo. Here, we further study the implications of this type of dissipative dark matter for disk galaxies. Building on earlier work, we develop a simple formalism which aims to describe the effects of dissipative dark matter in a fairly model independent way. This formalism is then applied to generic disk galaxies. We also consider specific examples, including NGC 1560 and a sample of dwarf galaxies from the LITTLE THINGS survey. We find that dissipative dark matter, as developed here, does a fairly good job accounting for the rotation curves of the galaxies considered. Not only does dissipative dark matter explain the linear rise of the rotational velocity of dwarf galaxies at small radii, but it can also explain the observed wiggles in rotation curves which are known to be correlated with corresponding features in the disk gas distribution.
Curved Radio Spectra of Weak Cluster Shocks
NASA Astrophysics Data System (ADS)
Kang, Hyesung; Ryu, Dongsu
2015-08-01
In order to understand certain observed features of arc-like giant radio relics such as the rareness, uniform surface brightness, and curved integrated spectra, we explore a diffusive shock acceleration (DSA) model for radio relics in which a spherical shock impinges on a magnetized cloud containing fossil relativistic electrons. Toward this end, we perform DSA simulations of spherical shocks with the parameters relevant for the Sausage radio relic in cluster CIZA J2242.8+5301, and calculate the ensuing radio synchrotron emission from re-accelerated electrons. Three types of fossil electron populations are considered: a delta-function like population with the shock injection momentum, a power-law distribution, and a power law with an exponential cutoff. The surface brightness profile of the radio-emitting postshock region and the volume-integrated radio spectrum are calculated and compared with observations. We find that the observed width of the Sausage relic can be explained reasonably well by shocks with speed {u}{{s}}˜ 3× {10}3 {km} {{{s}}}-1 and sonic Mach number {M}{{s}}˜ 3. These shocks produce curved radio spectra that steepen gradually over (0.1-10){ν }{br} with a break frequency {ν }{br}˜ 1 GHz if the duration of electron acceleration is ˜60-80 Myr. However, the abrupt increase in the spectral index above ˜1.5 GHz observed in the Sausage relic seems to indicate that additional physical processes, other than radiative losses, operate for electrons with {γ }{{e}}≳ {10}4.
Curved Radio Spectra of Weak Cluster Shocks
NASA Astrophysics Data System (ADS)
Kang, Hyesung; Ryu, Dongsu
2015-08-01
In order to understand certain observed features of arc-like giant radio relics such as the rareness, uniform surface brightness, and curved integrated spectra, we explore a diffusive shock acceleration (DSA) model for radio relics in which a spherical shock impinges on a magnetized cloud containing fossil relativistic electrons. Toward this end, we perform DSA simulations of spherical shocks with the parameters relevant for the Sausage radio relic in cluster CIZA J2242.8+5301, and calculate the ensuing radio synchrotron emission from re-accelerated electrons. Three types of fossil electron populations are considered: a delta-function like population with the shock injection momentum, a power-law distribution, and a power law with an exponential cutoff. The surface brightness profile of the radio-emitting postshock region and the volume-integrated radio spectrum are calculated and compared with observations. We find that the observed width of the Sausage relic can be explained reasonably well by shocks with speed {u}{{s}}∼ 3× {10}3 {km} {{{s}}}-1 and sonic Mach number {M}{{s}}∼ 3. These shocks produce curved radio spectra that steepen gradually over (0.1–10){ν }{br} with a break frequency {ν }{br}∼ 1 GHz if the duration of electron acceleration is ∼60–80 Myr. However, the abrupt increase in the spectral index above ∼1.5 GHz observed in the Sausage relic seems to indicate that additional physical processes, other than radiative losses, operate for electrons with {γ }{{e}}≳ {10}4.
SUPERNOVA LIGHT CURVES POWERED BY FALLBACK ACCRETION
Dexter, Jason; Kasen, Daniel
2013-07-20
Some fraction of the material ejected in a core collapse supernova explosion may remain bound to the compact remnant, and eventually turn around and fall back. We show that the late time ({approx}>days) power potentially associated with the accretion of this 'fallback' material could significantly affect the optical light curve, in some cases producing super-luminous or otherwise peculiar supernovae. We use spherically symmetric hydrodynamical models to estimate the accretion rate at late times for a range of progenitor masses and radii and explosion energies. The accretion rate onto the proto-neutron star or black hole decreases as M-dot {proportional_to}t{sup -5/3} at late times, but its normalization can be significantly enhanced at low explosion energies, in very massive stars, or if a strong reverse shock wave forms at the helium/hydrogen interface in the progenitor. If the resulting super-Eddington accretion drives an outflow which thermalizes in the outgoing ejecta, the supernova debris will be re-energized at a time when photons can diffuse out efficiently. The resulting light curves are different and more diverse than previous fallback supernova models which ignored the input of accretion power and produced short-lived, dim transients. The possible outcomes when fallback accretion power is significant include super-luminous ({approx}> 10{sup 44} erg s{sup -1}) Type II events of both short and long durations, as well as luminous Type I events from compact stars that may have experienced significant mass loss. Accretion power may unbind the remaining infalling material, causing a sudden decrease in the brightness of some long duration Type II events. This scenario may be relevant for explaining some of the recently discovered classes of peculiar and rare supernovae.
Inertial focusing of particles in curved microchannels
NASA Astrophysics Data System (ADS)
Joshi, Ketaki Neelkanth
Since the beginning of microfluidics, the ability to control motion of particles in microchannels has always been fascinating. Microfluidic techniques such as dielectrophoresis, magnetophoresis rely on externally applied fields to separate particles while others like hydrophoresis and deterministic lateral displacement depend on low Reynolds number operation for particle manipulation. One of these techniques is inertial focusing of particles in microchannels. The particles and channel interact to cause lateral migration of particles to equilibrium positions within channel cross-section in flow regime where inertia and viscosity of fluid are finite. Inertial focusing has wide range of applications in fields of chemical synthesis, biological analysis, multiphase flows, cell biology and many more. This thesis presents the study of inertial focusing of particles in spiral microchannels. Particle focusing in curved channel depends on number of parameters such as channel cross section, curvature of channel, size and shape of particles and flow parameters like channel Reynolds number. Effect of some of above mentioned parameters on inertial focusing of particles have been discussed in detail in this thesis. Effect of curvature of channel on inertial focusing in spiral channels has been studied. Microchannels with square and rectangular cross-section are considered in this study. Study of hydrodynamic focusing of particles in non-Newtonian fluid in curved channel is performed. The results are compared with those obtained for inertial focusing of particles in Newtonian fluids in spiral microchannel. The understanding of different factors influencing the particle behavior in spiral channels can be used to develop new and improved technologies in biomedical applications.
The rotation curves of gas and stars
NASA Astrophysics Data System (ADS)
Westfall, Kyle; Bershady, Matthew A.; MaNGA Team
2016-01-01
In its first year alone, the SDSS-IV/MaNGA survey has provided kinematic data useful for determining the rotation curves of both the ionized-gas and stellar components for hundreds of disk galaxies. We use these data to study the well-known Tully-Fisher relation in the local Universe, as well as the difference between the ionized-gas and stellar rotation curves in a novel study of asymmetric drift. The physical scenario for the latter is that gas efficiently dissipates energy allowing it to settle toward the circular speed of the galactic potential, whereas the stellar ensemble orbits more slowly because stars are collisionless and retain any non-circular motions accrued over their dynamical history. In disk galaxies with line-of-sight velocity dispersions that are well-measured with MaNGA's moderate spectral resolution, we demonstrate the correlation between asymmetric drift and stellar velocity dispersion, as expected by the dynamical relation between the two via the stellar phase-space distribution function. This correlation is consistent with measurements obtained at higher spectral resolution by the DiskMass Survey, and it allows us to leverage asymmetric drift to provide stellar velocity dispersion estimates that probe well below the instrumental dispersion. These velocity dispersion measurements can then be used to estimate the dynamical mass surface density of the baryon-dominated disk (Bershady et al. 2010, 2011). Thus, by combining our circular-speed data --- which yield a well-defined Tully-Fisher relation that is consistent with literature studies --- and our measurements of asymmetric drift, we discuss the implications for the dark-matter mass fractions of our galaxy sample. Statistically, our results are consistent with previous claims (e.g., Martinsson et al. 2013) that dark matter is a significant, even dominant, mass component within the effective radius of disk galaxies.
New Horizons approach photometry of Pluto and Charon: light curves and Solar phase curves
NASA Astrophysics Data System (ADS)
Zangari, A. M.; Buie, M. W.; Buratti, B. J.; Verbiscer, A.; Howett, C.; Weaver, H. A., Jr.; Olkin, C.; Ennico Smith, K.; Young, L. A.; Stern, S. A.
2015-12-01
While the most captivating images of Pluto and Charon were shot by NASA's New Horizons probe on July 14, 2015, the spacecraft also imaged Pluto with its LOng Range Reconnaissance Imager ("LORRI") during its Annual Checkouts and Approach Phases, with campaigns in July 2013, July 2014, January 2015, March 2015, April 2015, May 2015 and June 2015. All but the first campaign provided full coverage of Pluto's 6.4 day rotation. Even though many of these images were taken when surface features on Pluto and Charon were unresolved, these data provide a unique opportunity to study Pluto over a timescale of several months. Earth-based data from an entire apparition must be combined to create a single light curve, as Pluto is never otherwise continuously available for observing due to daylight, weather and scheduling. From the spacecraft, Pluto's sub-observer latitude remained constant to within 0.05 degrees of 43.15 degrees, comparable to a week's worth of change as seen from Earth near opposition. During the July 2013 to June 2015 period, Pluto's solar phase curve increased from 11 degrees to 15 degrees, a small range, but large compared to Earth's 2 degree limit. The slope of the solar phase curve hints at properties such as surface roughness. Using PSF photometry that takes into account the ever-increasing sizes of Pluto and Charon as seen from New Horizons, as well as surface features discovered at closest approach, we present rotational light curves and solar phase curves of Pluto and Charon. We will connect these observations to previous measurements of the system from Earth.
NASA Technical Reports Server (NTRS)
Honglu, Wu; Cucinotta, F.A.; Durante, M.; Lin, Z.; Rusek, A.
2006-01-01
The space environment consists of a varying field of radiation particles including high-energy ions, with spacecraft shielding material providing the major protection to astronauts from harmful exposure. Unlike low-LET gamma or X-rays, the presence of shielding does not always reduce the radiation risks for energetic charged particle exposure. Since the dose delivered by the charged particle increases sharply as the particle approaches the end of its range, a position known as the Bragg peak, the Bragg curve does not necessarily represent the biological damage along the particle traversal since biological effects are influenced by the track structure of both primary and secondary particles. Therefore, the biological Bragg curve is dependent on the energy and the type of the primary particle, and may vary for different biological endpoints. To achieve a Bragg curve distribution, we exposed cells to energetic heavy ions with the beam geometry parallel to a monolayer of fibroblasts. Qualitative analyses of gamma-H2AX fluorescence, a known marker of DSBs, indicated increased clustering of DNA damage before the Bragg peak, enhanced homogenous distribution at the peak, and provided visual evidence of high linear energy transfer (LET) particle traversal of cells beyond the Bragg peak. A quantitative biological response curve generated for micronuclei (MN) induction across the Bragg curve did not reveal an increased yield of MN at the location of the Bragg peak. However, the ratio of mono-to bi-nucleated cells, which indicates inhibition in cell progression, increased at the Bragg peak location. These results, along with other biological concerns, show that space radiation protection with shielding can be a complicated issue.
NASA Technical Reports Server (NTRS)
Demoss, J. F. (Compiler)
1971-01-01
Calibration curves for the Apollo 16 command service module pulse code modulation downlink and onboard display are presented. Subjects discussed are: (1) measurement calibration curve format, (2) measurement identification, (3) multi-mode calibration data summary, (4) pulse code modulation bilevel events listing, and (5) calibration curves for instrumentation downlink and meter link.
Semistable modifications of families of curves and compactified Jacobians
NASA Astrophysics Data System (ADS)
Esteves, Eduardo; Pacini, Marco
2016-04-01
Given a family of nodal curves, a semistable modification of it is another family made up of curves obtained by inserting chains of rational curves of any given length at certain nodes of certain curves of the original family. We give comparison theorems between torsion-free, rank-1 sheaves in the former family and invertible sheaves in the latter. We apply them to show that there are functorial isomorphisms between the compactifications of relative Jacobians of families of nodal curves constructed through Caporaso's approach and those constructed through Pandharipande's approach.
Light shaping along 3D curves and particle manipulation
NASA Astrophysics Data System (ADS)
Rodrigo, José A.; Alieva, Tatiana
2015-03-01
We present a non-iterative holographic technique for efficient and versatile laser beam shaping along arbitrary 3D curves. Light beams with intensity shaped for several 3D curves: Tilted ring, Viviani's curve, Archimedean spiral, and trefoil-knotted curve have been experimentally generated and applied for optical trapping of micrometer-sized dielectric particles. The high intensity gradients and independent phase control prescribed along the curve make this kind of laser trap attractive for multiple particle manipulation and allow for forward and backward motion to the light source. Indeed, different configurations of tractor beam traps are experimentally demonstrated. This technique can also be applied for laser micro-machining.
Automatic Sulcal Curve Extraction with MRF Based Shape Prior
Yang, Zhen; Carass, Aaron; Prince, Jerry. L.
2016-01-01
Extracting and labeling sulcal curves on the human cerebral cortex is important for many neuroscience studies, however manually annotating the sulcal curves is a time-consuming task. In this paper, we present an automatic sulcal curve extraction method by registering a set of dense landmark points representing the sulcal curves to the subject cortical surface. A Markov random field is used to model the prior distribution of these landmark points, with short edges in the graph preserving the curve structure and long edges modeling the global context of the curves. Our approach is validated using a leave-one-out strategy of training and evaluation on fifteen cortical surfaces, and a quantitative error analysis on the extracted major sulcal curves. PMID:27303593
Fitting Richards' curve to data of diverse origins
Johnson, D.H.; Sargeant, A.B.; Allen, S.H.
1975-01-01
Published techniques for fitting data to nonlinear growth curves are briefly reviewed, most techniques require knowledge of the shape of the curve. A flexible growth curve developed by Richards (1959) is discussed as an alternative when the shape is unknown. The shape of this curve is governed by a specific parameter which can be estimated from the data. We describe in detail the fitting of a diverse set of longitudinal and cross-sectional data to Richards' growth curve for the purpose of determining the age of red fox (Vulpes vulpes) pups on the basis of right hind foot length. The fitted curve is found suitable for pups less than approximately 80 days old. The curve is extrapolated to pre-natal growth and shown to be appropriate only for about 10 days prior to birth.
Guidelines for application of learning/cost improvement curves
NASA Technical Reports Server (NTRS)
Delionback, L. M.
1975-01-01
The differences between the terms learning curve and improvement curve are noted, as well as the differences between the Wright system and the Crawford system. Learning curve computational techniques were reviewed along with a method to arrive at a composite learning curve for a system given detail curves either by the functional techniques classification or simply categorized by subsystem. Techniques are discussed for determination of the theoretical first unit (TFU) cost using several of the currently accepted methods. Sometimes TFU cost is referred to as simply number one cost. A tabular presentation of the various learning curve slope values is given. A discussion of the various trends in the application of learning/improvement curves and an outlook for the future are presented.
Simplified curve fits for the thermodynamic properties of equilibrium air
NASA Technical Reports Server (NTRS)
Srinivasan, S.; Tannehill, J. C.; Weilmuenster, K. J.
1987-01-01
New, improved curve fits for the thermodynamic properties of equilibrium air have been developed. The curve fits are for pressure, speed of sound, temperature, entropy, enthalpy, density, and internal energy. These curve fits can be readily incorporated into new or existing computational fluid dynamics codes if real gas effects are desired. The curve fits are constructed from Grabau-type transition functions to model the thermodynamic surfaces in a piecewise manner. The accuracies and continuity of these curve fits are substantially improved over those of previous curve fits. These improvements are due to the incorporation of a small number of additional terms in the approximating polynomials and careful choices of the transition functions. The ranges of validity of the new curve fits are temperatures up to 25 000 K and densities from 10 to the -7 to 10 to the 3d power amagats.
GIS Method for Developing Wind Supply Curves
Kline, D.; Heimiller, D.; Cowlin, S.
2008-06-01
This report describes work conducted by the National Renewable Energy Laboratory (NREL) as part of the Wind Technology Partnership (WTP) sponsored by the U.S. Environmental Protection Agency (EPA). This project has developed methods that the National Development and Reform Commission (NDRC) intends to use in the planning and development of China's 30 GW of planned capacity. Because of China's influence within the community of developing countries, the methods and the approaches here may help foster wind development in other countries.
Asphaltenes yield curve measurements on a microfluidic platform.
Sieben, Vincent J; Tharanivasan, Asok Kumar; Ratulowski, John; Mostowfi, Farshid
2015-10-21
We describe a microfluidic apparatus and method for performing asphaltene yield measurements on crude oil samples. Optical spectroscopy measurements are combined with a microfluidic fluid handling platform to create an automated microfluidic apparatus to measure the asphaltene yield. The microfluidic measurements show good agreement with conventional wet chemistry measurements as well as available models. The initial absorbance of the oil is measured, and asphaltenes are removed from the oil by the gradual addition of n-alkane, which leads to flocculation and subsequent filtration. The absorbance of the de-asphalted oil (maltenes) is then measured and the initial asphaltene content is determined by the change in absorbance. The solubility of asphaltene is evaluated by varying the titrant-to-oil ratio (e.g., n-heptane-oil), which induces no, partial, or full precipitation of asphaltenes depending on the chosen ratio. The absorbance of the filtrate is measured and normalized to the maximum content to determine the fractional precipitation at each ratio. Traditionally, a yield curve comprised of 20 such ratios would require weeks to months to generate, while consuming over 6 L of solvent and more than 100 g of crude oil sample. Using the microfluidic approach described here, the same measurement can be performed in 1 day, with 0.5 L of solvent and 10 g of crude oil sample. The substantial reduction in time and consumables will enable more frequent asphaltene yield measurements and reduce its environmental impact significantly. PMID:26333290
A bottom-up method to develop pollution abatement cost curves for coal-fired utility boilers
This paper illustrates a new method to create supply curves for pollution abatement using boiler-level data that explicitly accounts for technology costs and performance. The Coal Utility Environmental Cost (CUECost) model is used to estimate retrofit costs for five different NO...
Learning curve for peroral endoscopic myotomy
El Zein, Mohamad; Kumbhari, Vivek; Ngamruengphong, Saowanee; Carson, Kathryn A.; Stein, Ellen; Tieu, Alan; Chaveze, Yamile; Ismail, Amr; Dhalla, Sameer; Clarke, John; Kalloo, Anthony; Canto, Marcia Irene; Khashab, Mouen A.
2016-01-01
Background and study aims: Although peroral endoscopic myotomy (POEM) is being performed more frequently, the learning curve for gastroenterologists performing the procedure has not been well studied. The aims of this study were to define the learning curve for POEM and determine which preoperative and intraoperative factors predict the time that will be taken to complete the procedure and its different steps. Patients and methods: Consecutive patients who underwent POEM performed by a single expert gastroenterologist for the treatment of achalasia or spastic esophageal disorders were included. The POEM procedure was divided into four steps: mucosal entry, submucosal tunneling, myotomy, and closure. Nonlinear regression was used to determine the POEM learning plateau and calculate the learning rate. Results: A total of 60 consecutive patients underwent POEM in an endoscopy suite. The median length of procedure (LOP) was 88 minutes (range 36 – 210), and the mean (± standard deviation [SD]) LOP per centimeter of myotomy was 9 ± 5 minutes. The total operative time decreased significantly as experience increased (P < 0.001), with a “learning plateau” at 102 minutes and a “learning rate” of 13 cases. The mucosal entry, tunneling, and closure times decreased significantly with experience (P < 0.001). The myotomy time showed no significant decrease with experience (P = 0.35). When the mean (± SD) total procedure times for the learning phase and the corresponding comparator groups were compared, a statistically significant difference was observed between procedures 11 – 15 and procedures 16 – 20 (15.5 ± 2.4 min/cm and 10.1 ± 2.7 min/cm, P = 0.01) but not thereafter. A higher case number was significantly associated with a decreased LOP (P < 0.001). Conclusion: In this single-center retrospective study, the minimum threshold number of cases required for an expert interventional endoscopist performing POEM to reach a
Growth curve analyses in selected duck lines.
Maruyama, K; Vinyard, B; Akbar, M K; Shafer, D J; Turk, C M
2001-12-01
1. Growth patterns of male ducks from 4 lines (lines A, B, C and D) selected for market weight were analysed and compared to growth patterns of ducks in the respective line 7 generations earlier. Growth curves were analysed using procedures derived from the Weibull sigmoidal function and the linear-linear relative growth rate model and simple allometry. 2. The ducks were fed ad libitum under 24-h lighting throughout the experiment. At weekly intervals from the time of hatch through 70 d of age, 16 ducks from each line were killed to determine body, carcase, breast-muscle, leg and thigh-muscle, and abdominal fat weights. 3. Line A was the heaviest line, followed by line B, line C and line D. However, body weight, carcase weight and breast-muscle weight at 49 d of age were not significantly different between lines A and B. After 7 generations of selection, the breast-muscle yield was increased to >19% and the abdominal fat percent was reduced to <1.4% in all lines. 4. The Weibull growth curve analysis of body weight showed an increase in the asymptotes during selection, while the age of the inflection point remained constant in all lines (21.3 to 26.0 d). For breast-muscle growth, ducks reached the inflection point 12.8 to 14.3 d later than for body weight. Between line A and line B, asymptotes for body weight, asymptotes for breast-muscle weight and allometric growth coefficients of breast muscle and leg and thigh muscles from 14 to 49 d were not significantly different. 5. The relative growth rate model discriminated body and breast-muscle growth patterns of line A and line B. The initial decline in the relative body growth rate was less and the time to reach the transition was longer in line A than line B. On the other hand, the initial decline in the relative breast-muscle growth rate was greater in line A than line B. PMID:11811908
Diurnal Curve of the Ocular Perfusion Pressure
Moreira, TCA; Bezerra, BSP; Vianello, MP; Corradi, J; Dorairaj, SK; Prata, TS
2016-01-01
ABSTRACT Purpose: To describe the diurnal variation of the ocular perfusion pressure (OPP) in normal, suspects and glaucoma patients. Materials and methods: Seventy-nine subjects were enrolled in a prospective study. The diurnal curve of intraocular pressure (IOP) was performed and blood pressure measurements were obtained. Each participant was grouped into one of the following based upon the clinical evaluation of the optic disk, IOP and standard achromatic perimetry (SAP): 18 eyes were classified as normal (normal SAP, normal optic disk evaluation and IOP < 21 mm Hg in two different measurements), 30 eyes as glaucoma suspect (GS) (normal SAP and mean deviation (MD), C/D ration > 0.5 or asymmetry > 0.2 and/or ocular hypertension), 31 eyes as early glaucoma (MD < -6 dB, glaucomatous optic neuropathy and SAP and MDs on SAP. Standard achromatic perimetry was performed with the Octopus 3.1.1 Dynamic 24-2 program. Intraocular pressure and blood pressure measurements were taken at 6 am, 9 am, 12, 3 and 6 pm. The patients stayed in the seated position for 5 minutes prior to blood pressure measurements. Results: The mean IOP values in all groups did not follow any regular pattern. The peak IOP was found to be greater in suspect [18.70 ± 3.31 (mm Hg ± SD)] and glaucoma (18.77 ± 4.30 mm Hg) patients as compared to normal subjects (16.11 ± 2.27 mm Hg). In studying the diurnal variation of the OPP, we found lower values at 3 pm in normals (34.21 ± 2.07 mm Hg), at 9 am in suspects (54.35 ± 3.32 mm Hg) and at 12 pm in glaucoma patients (34.84 ± 1.44 mm Hg). Conclusion: Each group has a specific OPP variation during the day with the most homogeneous group being the suspect one. It is important to keep studying the IOP and OPP variation for increased comprehension of the pathophysiology of glaucomatous optic neuropathy. How to cite this article: Kanadani FN, Moreira TCA, Bezerra BSP, Vianello MP, Corradi J, Dorairaj SK, Prata TS. Diurnal Curve of the Ocular Perfusion
McGreevy, John Austen; /Stanford U., Phys. Dept.
2005-07-06
This thesis is a study of D-branes in string compactifications. In this context, D-branes are relevant as an important component of the nonperturbative spectrum, as an incisive probe of these backgrounds, and as a natural stringy tool for localizing gauge interactions. In the first part of the thesis, we discuss half-BPS D-branes in compactifications of type II string theory on Calabi-Yau threefolds. The results we describe for these objects are pertinent both in their role as stringy brane-worlds, and in their role as solitonic objects. In particular, we determine couplings of these branes to the moduli determining the closed-string geometry, both perturbatively and non-perturbatively in the worldsheet expansion. We provide a local model for transitions in moduli space where the BPS spectrum jumps, and discuss the extension of mirror symmetry between Calabi-Yau manifolds to the case when D-branes are present. The next section is an interlude which provides some applications of D-branes to other curved backgrounds of string theory. In particular, we discuss a surprising phenomenon in which fundamental strings moving through background Ramond-Ramond fields dissolve into large spherical D3-branes. This mechanism is used to explain a previously-mysterious fact discovered via the AdS-CFT correspondence. Next, we make a connection between type IIA string vacua of the type discussed in the first section and M-theory compactifications on manifolds of G{sub 2} holonomy. Finally we discuss constructions of string vacua which do not have large radius limits. In the final part of the thesis, we develop techniques for studying the worldsheets of open strings ending on the curved D-branes studied in the first section. More precisely, we formulate a large class of massive two-dimensional gauge theories coupled to boundary matter, which flow in the infrared to the relevant boundary conformal field theories. Along with many other applications, these techniques are used to describe
Constructing a Neoproterozoic Seawater Strontium Isotope Curve
NASA Astrophysics Data System (ADS)
Zhou, Y.; Shields-Zhou, G. A.; Manning, C. J.; Thirlwall, M.; Thurow, J. W.; Zhu, M.; Ling, H.
2014-12-01
The strontium isotopic composition of seawater has varied throughout Earth history in response to the balance between Sr isotopic exchange with ocean crust and input of riverine Sr derived from continental weathering. Because of this, seawater 87Sr/86Sr highs are interpreted to reflect erosion events, related to mountain building, while 87Sr/86Sr lows are considered to result from low weathering rates or increased seafloor spreading. Seawater 87Sr/86Sr also responds to changes in the isotopic composition of material undergoing weathering. The largest ever increase in seawater 87Sr/86Sr took place sometime from approximately 900 Ma to 500 Ma, and was associated with a permanent step shift in baseline 87Sr/86Sr composition. The unprecedented size of this increase, its timing and causation remains unconstrained. This study attempts firstly to reconstruct global seawater 87Sr/86Sr trends through this increase, using well-preserved carbonate rock samples from the North China craton, calibrated against additional 87Sr/86Sr and δ13C data from Neoproterozoic samples collected from other sections around the world. Sample preparation techniques for bulk carbonate Sr isotope stratigraphy are being honed during the course of this study. Other stable isotope systems (δ13C and δ18O) and trace elements, including REE have been investigated on the same samples to identify pristine samples for Sr isotope analysis and help in interpretation. The newly obtained data from this study (mainly Huaibei group of Huaibei area), using the excellently preserved early marine calcite cements and some bulk rock samples, confirm that the carbonate strata across the Jiao-Liao-Xu-Huai stratigraphic realm of the North China Craton exhibit the moderately positive δ13C values and low 87Sr/86Sr values that are characteristic of the early Neoproterozoic (Tonian).The results help to recreate the global curve by linking negative excursions in the Shijia (Xuzhou) (Xiao et al., 2014, Precambr. Res., 246
Chekroun, Mathieu; Minonzio, Jean-Gabriel; Prada, Claire; Laugier, Pascal; Grimal, Quentin
2016-02-01
A method is proposed to evaluate in a non-contact way the phase velocity dispersion curves of circumferential waves around a shell of arbitrary shape immersed in a fluid. No assumptions are made about the thickness or the material of the shell. A geometrical model is derived to describe the shape of the radiated wavefronts in the surrounding fluid, and predict the positions of its centers of curvature. Then the time-reversal principle is applied to recover these positions and to calculate the phase velocity of the circumferential waves. Numerical finite-difference simulations are performed to evaluate the method on a circular and on an elliptic thin shell. Different dispersion curves can be recovered with an error of less than 10%. PMID:26936561
Dallaston, Michael C.
2016-01-01
Motivated by a problem from fluid mechanics, we consider a generalization of the standard curve shortening flow problem for a closed embedded plane curve such that the area enclosed by the curve is forced to decrease at a prescribed rate. Using formal asymptotic and numerical techniques, we derive possible extinction shapes as the curve contracts to a point, dependent on the rate of decreasing area; we find there is a wider class of extinction shapes than for standard curve shortening, for which initially simple closed curves are always asymptotically circular. We also provide numerical evidence that self-intersection is possible for non-convex initial conditions, distinguishing between pinch-off and coalescence of the curve interior. PMID:26997898
Langton, S.
1984-01-01
A resource for professional and volunteer managers of environmental organizations, this book provides instruction for raising funds, writing proposals, lobbying, utilizing the media, and maximizing human resources. Langton also assesses the environmental movement's future.
Environmental chemistry is applied to estimating the exposure of ecosystems and humans to various chemical environmental stressors. Among the stressors of concern are mercury, pesticides, and arsenic. Advanced analytical chemistry techniques are used to measure these stressors ...
... system to a normally harmless substance called an allergen. A variety of environmental allergens, such as pollen and animal dander, can trigger ... allergies. Understanding Environmental Allergies Cause Symptoms Diagnosis Treatments Immunotherapy Last Updated April 22, 2015 CONNECT WITH NIAID ...
The J-Curve Phenomenon in Hypertension
Kang, Yuan-Yuan; Wang, Ji-Guang
2016-01-01
Almost immediately after antihypertensive therapy was proven effective in preventing cardiovascular events, the J-curve issue emerged as a hot topic. The Hypertension Optimal Treatment (HOT) trial attempted to address this question (diastolic blood pressure <80, <85, and <90 mm Hg) but ended up with a post hoc analysis indicating a nadir of 138.5 mm Hg systolic and 82.6 mm Hg diastolic blood pressure. Nevertheless, this observational finding was supported by the results of observational studies in the general population and by post hoc analyses of antihypertensive treatment trials. The currently ongoing Systolic Hypertension Optimal Treatment (SHOT) trial investigates whether the relationship between systolic blood pressure and stroke recurrence is linear or J-shaped by treating systolic blood pressure to <125, <135, and <145 mm Hg in patients with a history of recent stroke. This trial may provide additional but probably inconclusive evidence, because optimal blood pressure might differ between individuals and across outcomes. Nevertheless, a universal beneficial, instead of optimal, level of blood pressure for antihypertensive treatment may exist approximating 130/80 mm Hg and should be investigated by comparing 130/80 mm Hg with 140/90 mm Hg as a target blood pressure in hypertensive patients with the simultaneous use of modern blood pressure measuring techniques, such as home and ambulatory blood pressure monitoring. PMID:27493904
Interactive dependency curves for resilience management.
Petit, Frédéric; Wallace, Kelly; Phillip, Julia
Physical dependencies are a fundamental consideration when assessing the resilience of an organisation and, ultimately, the resilience of a region. Every organisation needs specific resources for supporting its operations. A disruption in the supply of these resources can severely impact business continuity. It is important to characterise dependencies thoroughly when seeking to reduce the extent an organisation is directly affected by the missions, functions and operations of other organisations. The general protocol when addressing each critical resource is to determine the use for the resource, whether there are redundant services providing the resource, and what protections, backup equipment and arrangements are in place to maintain service. Finally, the criticality of the resource is determined by estimating the time it will take for the facility to experience a severe impact once primary service is lost and what percentage of facility operations can be maintained without backup service in place, as well as identifying whether any external regulations/policies are in place that require shutdown of the facility because of service disruption owing to lack of a critical resource. All of this information can be presented in the form of interactive dependency curves that help anticipate and manage the effect(s) of a disruption on critical resources supply. PMID:25416376
Simulating Radiation Transport in Curved Spacetimes
NASA Astrophysics Data System (ADS)
Endeve, Eirik; Hauck, Cory; Xing, Yulong; Cardall, Christian; Mezzacappa, Anthony
2014-03-01
We are developing methods for simulation of radiation transport in systems governed by strong gravity (e.g., neutrino transport in core-collapse supernovae). By employing conservative formulations of the general relativistic Boltzmann equation, we aim to develop methods that are (i) high-order accurate for computational efficiency; (ii) robust in the sense that the phase space density f preserves the maximum principle of the physical model (f ∈ [ 0 , 1 ] for fermions); and (iii) applicable to curvilinear coordinate systems to accommodate curved spacetimes, which result in gravity-induced frequency shift and angular aberration. Our approach is based on the Runge-Kutta discontinuous Galerkin method, which has many attractive properties, including high-order accuracy on a compact stencil. We present the physical model, describe our numerical methods, and show results from implementations in spherical and axial symmetry. Our tests show that the method is high-order accurate and strictly preserves the maximum principle on f. We also demonstrate the ability of our method to accurately include effects of a strong gravitational field.
Leptogenesis from loop effects in curved spacetime
NASA Astrophysics Data System (ADS)
McDonald, Jamie I.; Shore, Graham M.
2016-04-01
We describe a new mechanism — radiatively-induced gravitational leptogenesis — for generating the matter-antimatter asymmetry of the Universe. We show how quantum loop effects in C and CP violating theories cause matter and antimatter to propagate differently in the presence of gravity, and prove this is forbidden in flat space by CPT and translation symmetry. This generates a curvature-dependent chemical potential for leptons, allowing a matter-antimatter asymmetry to be generated in thermal equilibrium in the early Universe. The time-dependent dynamics necessary for leptogenesis is provided by the interaction of the virtual self-energy cloud of the leptons with the expanding curved spacetime background, which violates the strong equivalence principle and allows a distinction between matter and antimatter. We show here how this mechanism is realised in a particular BSM theory, the see-saw model, where the quantum loops involve the heavy sterile neutrinos responsible for light neutrino masses. We demonstrate by explicit computation of the relevant two-loop Feynman diagrams how the size of the radiative corrections relevant for leptogenesis becomes enhanced by increasing the mass hierarchy of the sterile neutrinos, and show how the induced lepton asymmetry may be sufficiently large to play an important rôle in determining the baryon-to-photon ratio of the Universe.
Reduced Calibration Curve for Proton Computed Tomography
NASA Astrophysics Data System (ADS)
Yevseyeva, Olga; de Assis, Joaquim; Evseev, Ivan; Schelin, Hugo; Paschuk, Sergei; Milhoretto, Edney; Setti, João; Díaz, Katherin; Hormaza, Joel; Lopes, Ricardo
2010-05-01
The pCT deals with relatively thick targets like the human head or trunk. Thus, the fidelity of pCT as a tool for proton therapy planning depends on the accuracy of physical formulas used for proton interaction with thick absorbers. Although the actual overall accuracy of the proton stopping power in the Bethe-Bloch domain is about 1%, the analytical calculations and the Monte Carlo simulations with codes like TRIM/SRIM, MCNPX and GEANT4 do not agreed with each other. A tentative to validate the codes against experimental data for thick absorbers bring some difficulties: only a few data is available and the existing data sets have been acquired at different initial proton energies, and for different absorber materials. In this work we compare the results of our Monte Carlo simulations with existing experimental data in terms of reduced calibration curve, i.e. the range—energy dependence normalized on the range scale by the full projected CSDA range for given initial proton energy in a given material, taken from the NIST PSTAR database, and on the final proton energy scale—by the given initial energy of protons. This approach is almost energy and material independent. The results of our analysis are important for pCT development because the contradictions observed at arbitrary low initial proton energies could be easily scaled now to typical pCT energies.
Quantum causality in closed timelike curves
NASA Astrophysics Data System (ADS)
Korotaev, S. M.; Kiktenko, E. O.
2015-08-01
Although general relativity allows the existence of closed timelike curves (CTCs), self-consistency problems arise (the ‘grandfather paradox’ among others). It is known that quantum mechanical consideration of the matter formally removes all the paradoxes, but the questions about causal structure remain. On the other hand, the idea of postselected CTCs (P-CTC) in quantum teleportation has know been put forward and experimentally implemented. We consider these problems with the aid of quantum causal analysis, where causality is defined without invoking the time relation. It implements the Cramer principle of weak causality, which admits time reversal in entangled states. We analyze Deutsch CTCs (D-CTC) with different kinds of interactions between the chronology-violating and chronology-respecting particles, with refined inferences about mixedness, quantum/classical correlations, entanglement and thermodynamics in the D-CTC. The main result is that time reversal causality can really exist, however, the final quantum state does not place retrospective constraints on the initial state, instead the final state can influence the state inside the D-CTC. This is effectively the implementation of Novikov self-consistency principle. The P-CTC has radically different properties; in particular, if the initial state was pure, the final state is always pure too. Self-consistency is controlled by the initial state-dependent traversability of the P-CTC.
A cleavage toughness master curve model
NASA Astrophysics Data System (ADS)
Odette, G. R.; He, M. Y.
2000-12-01
Development of fusion power will require a fracture toughness database, derived largely from small specimen tests, closely integrated with methods to assess first wall and blanket structural integrities. A master curve-shift (MC-ΔT) method has been proposed as an engineering expedient to treat the effects of structural geometry, irradiation, loading rates and safety margins. However, a number of issues related to the MC-ΔT method remain to be resolved, including the universality of MC shapes. A new micromechanical model of fracture toughness in the cleavage transition regime is proposed that combines analytical representations of finite element analysis simulations of crack-tip stress fields with a local critical stress-critical stressed area (σ∗-A∗) fracture criterion. This model, has been successful in predicting geometry effects, as well as high loading rate and irradiation hardening-induced Charpy shifts. By incorporating a modest temperature dependence in σ∗(T), an inconsistency between model predictions and an observed universal-type MC shape is resolved.
Curved Lobate Scarp on Crater Floor
NASA Technical Reports Server (NTRS)
1974-01-01
A broadly curved lobate scarp (running from left to right in the large crater to the right of center in this image) is restricted to the floor of a crater 85 kilometers in diameter. The rim of this crater and the rims of those north of it have been disrupted by the process which caused the hilly and lineated terrain. This process has not affected the smooth plains on their floors, indicating that the floor materials post date the formation of the craters. In this case, the scarp on the crater floor may be a flow front formed during emplacement of the floor material.
This image (FDS 27379) was acquired during the spacecraft's first encounter with Mercury.
The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.
Image Credit: NASA/JPL/Northwestern University
NONPARAMETRIC BAYESIAN ESTIMATION OF PERIODIC LIGHT CURVES
Wang Yuyang; Khardon, Roni; Protopapas, Pavlos
2012-09-01
Many astronomical phenomena exhibit patterns that have periodic behavior. An important step when analyzing data from such processes is the problem of identifying the period: estimating the period of a periodic function based on noisy observations made at irregularly spaced time points. This problem is still a difficult challenge despite extensive study in different disciplines. This paper makes several contributions toward solving this problem. First, we present a nonparametric Bayesian model for period finding, based on Gaussian Processes (GPs), that does not make assumptions on the shape of the periodic function. As our experiments demonstrate, the new model leads to significantly better results in period estimation especially when the light curve does not exhibit sinusoidal shape. Second, we develop a new algorithm for parameter optimization for GP which is useful when the likelihood function is very sensitive to the parameters with numerous local minima, as in the case of period estimation. The algorithm combines gradient optimization with grid search and incorporates several mechanisms to overcome the high computational complexity of GP. Third, we develop a novel approach for using domain knowledge, in the form of a probabilistic generative model, and incorporate it into the period estimation algorithm. Experimental results validate our approach showing significant improvement over existing methods.
Folding of non-Euclidean curved shells
NASA Astrophysics Data System (ADS)
Bende, Nakul; Evans, Arthur; Innes-Gold, Sarah; Marin, Luis; Cohen, Itai; Santangelo, Christian; Hayward, Ryan
2015-03-01
Origami-based folding of 2D sheets has been of recent interest for a variety of applications ranging from deployable structures to self-folding robots. Though folding of planar sheets follows well-established principles, folding of curved shells involves an added level of complexity due to the inherent influence of curvature on mechanics. In this study, we use principles from differential geometry and thin shell mechanics to establish fundamental rules that govern folding of prototypical creased shells. In particular, we show how the normal curvature of a crease line controls whether the deformation is smooth or discontinuous, and investigate the influence of shell thickness and boundary conditions. We show that snap-folding of shells provides a route to rapid actuation on time-scales dictated by the speed of sound. The simple geometric design principles developed can be applied at any length-scale, offering potential for bio-inspired soft actuators for tunable optics, microfluidics, and robotics. This work was funded by the National Science Foundation through EFRI ODISSEI-1240441 with additional support to S.I.-G. through the UMass MRSEC DMR-0820506 REU program.
Mitchell, R.
1992-01-01
This book covers issues ranging from global climate changes to biocontrol of plant diseases. Many of its contributions stress how new technologies in areas such as molecular biology and environmental engineering expand understanding and applications of basic concepts in environmental microbiology. Articles in the book are in three basic subject areas: effects of environmental contamination on the role of microbes in geochemical cycling of the major elements, pathogens in the environment, and microbial activities in environmental management.
NASA Technical Reports Server (NTRS)
1980-01-01
Burns & McDonnell Engineering's environmental control study is assisted by NASA's Computer Software Management and Information Center's programs in environmental analyses. Company is engaged primarily in design of such facilities as electrical utilities, industrial plants, wastewater treatment systems, dams and reservoirs and aviation installations. Company also conducts environmental engineering analyses and advises clients as to the environmental considerations of a particular construction project. Company makes use of many COSMIC computer programs which have allowed substantial savings.
Free vibration of shallow and deep curved FG nanobeam via nonlocal Timoshenko curved beam model
NASA Astrophysics Data System (ADS)
Hosseini, S. A. H.; Rahmani, O.
2016-03-01
A free vibration analysis of shallow and deep curved functionally graded (FG) nanobeam is presented. Differential equations and boundary conditions are obtained using Hamilton's principle, and then, nonlocal theory is employed to derive differential equations in small scale. Properties of the material are FG in radial direction. In order to investigate the effects of deep curved beam, extensional stiffness, bending-extension coupling stiffness, and bending stiffness are calculated in the deep case, analytically. By employing Navier method, an analytical solution is presented. Results are compared and validated with available studies, and a good agreement is seen. The influences of effective parameters such as geometrical deep term, nonlocal parameter, opening angle, aspect ratio, mode number, and gradient index are discussed in detail. It is found that the frequency of deep curved nanobeam is higher than that of shallow one, and the aspect ratio significantly affects this difference to decrease. Also, it is concluded that the opening angle, nonlocal parameter, and power gradient index can notably influence the amount of frequency.
Do the Kepler AGN light curves need reprocessing?
NASA Astrophysics Data System (ADS)
Kasliwal, Vishal P.; Vogeley, Michael S.; Richards, Gordon T.; Williams, Joshua; Carini, Michael T.
2015-10-01
We gauge the impact of spacecraft-induced effects on the inferred variability properties of the light curve of the Seyfert 1 AGN Zw 229-15 observed by Kepler. We compare the light curve of Zw 229-15 obtained from the Kepler MAST data base with a reprocessed light curve constructed from raw pixel data. We use the first-order structure function, SF(δt), to fit both light curves to the damped power-law PSD (power spectral density) of Kasliwal et al. On short time-scales, we find a steeper log PSD slope (γ = 2.90 to within 10 per cent) for the reprocessed light curve as compared to the light curve found on MAST (γ = 2.65 to within 10 per cent) - both inconsistent with a damped random walk (DRW) which requires γ = 2. The log PSD slope inferred for the reprocessed light curve is consistent with previous results that study the same reprocessed light curve. The turnover time-scale is almost identical for both light curves (27.1 and 27.5 d for the reprocessed and MAST data base light curves). Based on the obvious visual difference between the two versions of the light curve and on the PSD model fits, we conclude that there remain significant levels of spacecraft-induced effects in the standard pipeline reduction of the Kepler data. Reprocessing the light curves will change the model inferenced from the data but is unlikely to change the overall scientific conclusions reached by Kasliwal et al. - not all AGN light curves are consistent with the DRW.
ERIC Educational Resources Information Center
Columbus State Community Coll., OH.
This document contains materials developed for and about the environmental technology tech prep program of the South-Western City Schools in Ohio. Part 1 begins with a map of the program, which begins with an environmental science technology program in grades 11 and 12 that leads to entry-level employment or a 2-year environmental technology…
Conable, B.; Warford, J.; Partow, Z.; Lutz, E.; Munasinghe, M.
1991-09-01
The contents include the following: Development and the Environment: A Global Balance; Evolution of the World Bank's Environmental Policy; Accounting for the Environment; Public Policy and the Environment; Managing Drylands; Environmental Action Plans in Africa; Agroforestry in Sub-Saharan Africa; Irrigation and the Environmental Challenge; Curbing Pollution in Developing Countries; Global Warming and the Developing World; and The Global Environment Facility.
ERIC Educational Resources Information Center
Bandhu, Desh, Ed.; Aulakh, G. S., Ed.
In India, environmental education (EE) is introduced at various levels. Goals of this country's EE programs include: improving the quality of environment to create awareness among the people on environmental problems and conservation; developing skills to solve environmental problems; creating the necessary atmosphere for citizen participation in…
Prediction of stable crack growth and instability using the V sub R-curve method
NASA Technical Reports Server (NTRS)
Newman, J. C., Jr.
1985-01-01
A methodology is presented for predicting stable crack growth and instability of cracked structural components from results of laboratory tests on metallic materials under plane-stress conditions. The methodology is based on the displacement V sub R at the tip of a stably tearing crack. Basically, the V sub R-curve method is a resistance curve approach, such as K sub R and J sub R, except that the 'crack drive' is written in terms of crack-tip displacement instead of K or J. The relationship between crack-tip-opening displacement, crack length, specimen type, and tensile properties is derived from the Dugdale model for the cracked structure of interest. This report describes the laboratory test procedure and calculations used to obtain the V sub R resistance curve from fracture tests of compact or of middle-crack tension (formally center-crack) specimens. The analysis procedure used to predict stable crack growth and instability of any through-the-thickness crack configuration made of the same material and thickness, and tested under the same environmental conditions, is presented. The various limitations of the present V sub R curve method are given. Four example calculations and predictions are shown.
Dynamics of dislocations described as evolving curves interacting with obstacles
NASA Astrophysics Data System (ADS)
Pauš, Petr; Beneš, Michal; Kolář, Miroslav; Kratochvíl, Jan
2016-03-01
In this paper we describe the model of glide dislocation interaction with obstacles based on the planar curve dynamics. The dislocations are represented as smooth curves evolving in a slip plane according to the mean curvature motion law, and are mathematically described by the parametric approach. We enhance the parametric model by employing so called tangential redistribution of curve points to increase the stability during numerical computation. We developed additional algorithms for topological changes (i.e. merging and splitting of dislocation curves) enabling a detailed modelling of dislocation interaction with obstacles. The evolving dislocations are approximated as a moving piece-wise linear curves. The obstacles are represented as idealized circular areas of a repulsive stress. Our model is numerically solved by means of semi-implicit flowing finite volume method. We present results of qualitative and quantitative computational studies where we demonstrate the topological changes and discuss the effect of tangential redistribution of curve points on computational results.
Spitzer IRAC Sparsely Sampled Phase Curve of WASP-14b
NASA Astrophysics Data System (ADS)
Krick, Jessica; Ingalls, James G.; Carey, Sean; von Braun, Kaspar; Ciardi, David; Kane, Stephen
2015-08-01
We present a new technique of sparsely sampling phase curves of hot jupiters with Spitzer IRAC. Snapshot phase curves are enabled by technical advances of precision pointing as well as careful characterization of a portion of the central pixel on the array. This method allows for observations which are a factor of ~2 more efficient than full phase curve observations, and are easy to schedule. We present the first results from this program using the exoplanet WASP-14b. As our pilot study, this planet has data taken both as a sparsely sampled phase curve as well as a staring mode phase curve as proof of technique. We successfully recover physical parameters for the transit and eclipse depths as well as phase curve shape of this slightly eccentric hot jupiter.
Symmetric Galerkin boundary formulations employing curved elements
NASA Technical Reports Server (NTRS)
Kane, J. H.; Balakrishna, C.
1993-01-01
Accounts of the symmetric Galerkin approach to boundary element analysis (BEA) have recently been published. This paper attempts to add to the understanding of this method by addressing a series of fundamental issues associated with its potential computational efficiency. A new symmetric Galerkin theoretical formulation for both the (harmonic) heat conduction and the (biharmonic) elasticity problem that employs regularized singular and hypersingular boundary integral equations (BIEs) is presented. The novel use of regularized BIEs in the Galerkin context is shown to allow straightforward incorporation of curved, isoparametric elements. A symmetric reusable intrinsic sample point (RISP) numerical integration algorithm is shown to produce a Galerkin (i.e., double) integration strategy that is competitive with its counterpart (i.e., singular) integration procedure in the collocation BEA approach when the time saved in the symmetric equation solution phase is also taken into account. This new formulation is shown to be capable of employing hypersingular BIEs while obviating the requirement of C 1 continuity, a fact that allows the employment of the popular continuous element technology. The behavior of the symmetric Galerkin BEA method with regard to both direct and iterative equation solution operations is also addressed. A series of example problems are presented to quantify the performance of this symmetric approach, relative to the more conventional unsymmetric BEA, in terms of both accuracy and efficiency. It is concluded that appropriate implementations of the symmetric Galerkin approach to BEA indeed have the potential to be competitive with, if not superior to, collocation-based BEA, for large-scale problems.
Phacoemulsification--a senior surgeon's learning curve.
Thomas, R; Braganza, A; Raju, R; Lawrence; Spitzer, K H
1994-08-01
We sought to prospectively document and evaluate the learning curve of an experienced extracapsular surgeon making a supervised transition from extracapsular cataract extraction (ECCE) to phacoemulsification. Over a period of 2 weeks, 51 phacoemulsification procedures using an endocapsular nucleofractis technique were performed by a single senior surgeon at the Christian Medical College in Vellore, India under the supervision of a visiting US expert with more than 15 years' experience in the technique. Vitreous loss occurred in seven eyes (six prior to the stage of cortical aspiration); failure of capsulorhexis necessitated conversion to standard ECCE in four. Injury to the inferior iris during phacoemulsification was cosmetically significant in three eyes. Two eyes had mild persistent localized corneal edema, but there were no instances of permanent corneal damage. One eye had intraoperative displacement of the nucleus into the vitreous. In one eye with vitreous loss, the implanted intraocular lens dislocated into the vitreous cavity. Two patients had clinically detectable cystoid macular edema at 6 weeks. Eleven patients were lost to follow up after 3 weeks. Six weeks after surgery, 36 of the remaining 40 eyes (90%) had achieved a best-corrected visual acuity of 6/6. We conclude that phacoemulsification requires supervised learning, even for an experienced surgeon. Complications still occurred, but were restricted to the unfamiliar steps of the surgery. Factors identified in the first 2 days of surgery (10 cases) as critical in the smooth transition to phacoemulsification were careful selection of initial cases, a successful capsulorhexis, and hydrodissection with vigorous nucleus mobilization.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7970530
Boston, H.L.
1990-10-12
The traveler participated in a conference on environmental technology in Paris, sponsored by the US Embassy-Paris, US Environmental Protection Agency (EPA), the French Environmental Ministry, and others. The traveler sat on a panel for environmental aspects of energy technology and made a presentation on the potential contributions of Oak Ridge National Laboratory (ORNL) to a planned French-American Environmental Technologies Institute in Chattanooga, Tennessee, and Evry, France. This institute would provide opportunities for international cooperation on environmental issues and technology transfer related to environmental protection, monitoring, and restoration at US Department of Energy (DOE) facilities. The traveler also attended the Fourth International Conference on Environmental Contamination in Barcelona. Conference topics included environmental chemistry, land disposal of wastes, treatment of toxic wastes, micropollutants, trace organics, artificial radionuclides in the environment, and the use biomonitoring and biosystems for environmental assessment. The traveler presented a paper on The Fate of Radionuclides in Sewage Sludge Applied to Land.'' Those findings corresponded well with results from studies addressing the fate of fallout radionuclides from the Chernobyl nuclear accident. There was an exchange of new information on a number of topics of interest to DOE waste management and environmental restoration needs.
Empirical rainfall thresholds and copula based IDF curves for shallow landslides and flash floods
NASA Astrophysics Data System (ADS)
Bezak, Nejc; Šraj, Mojca; Brilly, Mitja; Mikoš, Matjaž
2015-04-01
Large mass movements, like deep-seated landslides or large debris flows, and flash floods can endanger human lives and cause huge environmental and economic damage in hazard areas. The main objective of the study was to investigate the characteristics of selected extreme rainfall events, which triggered landslides and caused flash floods, in Slovenia in the last 25 years. Seven extreme events, which occurred in Slovenia (Europe) in the last 25 years (1990-2014) and caused 17 casualties and about 500 million Euros of economic loss, were analysed in this study. Post-event analyses showed that rainfall characteristics triggering flash floods and landslides are different where landslides were triggered by longer duration (up to one or few weeks) rainfall events and flash floods by short duration (few hours to one or two days) rainfall events. The sensitivity analysis results indicate that inter-event time variable, which is defined as the minimum duration of the period without rain between two consecutive rainfall events, and sample definition methodology can have significant influence on the position of rainfall events in the intensity-duration space, on the constructed intensity-duration-frequency (IDF) curves and on the relationship between the empirical rainfall threshold curves and IDF curves constructed using copula approach. The empirical rainfall threshold curves (ID curves) were also evaluated for the selected extreme events. The results indicate that a combination of several empirical rainfall thresholds with appropriate high density of rainfall measuring network can be used as part of the early warning system for initiation of landslides and debris flows. However, different rainfall threshold curves should be used for lowland and mountainous areas in Slovenia. Furthermore, the intensity-duration-frequency (IDF) relationship was constructed using the Frank copula functions for 16 pluviographic meteorological stations in Slovenia using the high resolution
Multi-curve spectrum representation of facial movements and expressions
NASA Astrophysics Data System (ADS)
Pei, Li; Zhang, Zhijiang; Chen, Zhixiang; Zeng, Dan
2009-07-01
This paper presents a method of multi-curve spectrum representation of facial movements and expressions. Based on 3DMCF (3D muscle-controlled facial) model, facial movements and expressions are controlled by 21 virtual muscles. So, facial movements and expressions can be described by a group of time-varying curves of normalized muscle contraction, called multi-curve spectrum. The structure and basic characters of multi-curve spectrum is introduced. The performance of the proposed method is among the best. This method needs small quantity of data, and is easy to apply. It can also be used to transplant facial animation between different faces.
Technological growth curves. A competition of forecasting models
Young, P.
1993-12-01
In order to determine procedures for appropriate model selection of technological growth curves, numerous time series that were representative of growth behavior were collected and categorized according to data characteristics. Nine different growth curve models were each fitted onto the various data sets in an attempt to determine which growth curve models achieved the best forecasts for differing types of growth data. The analysis of the results gives rise to a new approach for selecting appropriate growth curve models for a given set of data, prior to fitting the models, based on the characteristics of the data sets. 58 refs., 9 tabs.
Study of galactic rotation curves in wormhole spacetime
NASA Astrophysics Data System (ADS)
Rahaman, Farook; Sen, Banashree; Chakraborty, Koushik; Shit, G. C.
2016-03-01
The spacetime of the galactic halo region is described by a wormhole like line element. We assume violation of Null Energy Condition (NEC) in the galactic halo. The Einstein Field equations are solved for two different conditions of pressure and density to obtain physical parameters like tangential velocity of test particles and parameters related to the wormhole geometry. The theoretical rotation curve of the test particles is plotted and compared the same with an observed rotation curve. We obtain a satisfactory fit between the observed curve and the curve obtained from the present theory for the radial distances in the range 9 Kpc to 100 Kpc.
Ankle moment generation and maximum-effort curved sprinting performance.
Luo, Geng; Stefanyshyn, Darren
2012-11-15
Turning at high speed along acute curves is crucial for athletic performance. One determinant of curved sprinting speed is the ground reaction force that can be created by the supporting limb; the moment generated at the ankle joint may influence such force generation. Body lean associated with curved sprints positions the ankle joints in extreme in-/eversion, and may hinder the ankle moment generation. To examine the influence of ankle moment generation on curved sprinting performance, 17 male subjects performed maximum-effort curved sprints in footwear with and without a wedge. The wedged footwear was constructed with the intention to align the ankle joints closer to their neutral frontal-plane configuration during counter-clockwise curved sprints so greater joint moments might be generated. We found, with the wedged footwear, the average eversion angle of the inside leg ankle was reduced, and the plantarflexion moment generation increased significantly. Meanwhile, the knee extension moment remained unchanged. With the wedged footwear, stance-average centripetal ground reaction force increased significantly while no difference in the vertical ground reaction force was detected. The subjects created a greater centripetal ground reaction impulse in the wedged footwear despite a shortened stance phase when compared to the control. Stance-average curved sprinting speed improved by 4.3% with the wedged footwear. The changes in ankle moment and curved sprinting speed observed in the current study supports the notion that the moment generation at the ankle joint may be a performance constraint for curved sprinting. PMID:23022207
Propagation of guided modes in curved nanoribbon waveguides
Yang, P.; Ye, Zhuo; Hu, Xinhua; Li, Ming; Ho, Kai-Ming
2006-08-23
The authors develop a plane-wave-based transfer matrix method in curvilinear coordinates to study the guided modes in curved nanoribbon waveguides. The problem of a curved structure is transformed into an equivalent one of a straight structure with spatially dependent tensors of dielectric constant and magnetic permeability. The authors investigate the coupling between the eigenmodes of the straight part and those of the curved part when the waveguide is bent. The authors show that curved sections can result in strong oscillations in the transmission spectrum similar to the recent experimental results of Lawet al.
Chopra, O. K.; Smith, J. L.
1998-02-12
The ASME Boiler and Pressure Vessel Code design fatigue curves for structural materials do not explicitly address the effects of reactor coolant environments on fatigue life. Recent test data indicate a significant decrease in fatigue lives of austenitic stainless steels (SSs) in light water reactor (LWR) environments. Unlike those of carbon and low-alloy steels, environmental effects on fatigue lives of SSs are more pronounced in low-dissolved-oxygen (low-DO) water than in high-DO water, This paper summarizes available fatigue strain vs. life data on the effects of various material and loading variables such as steel type, DO level, strain range, and strain rate on the fatigue lives of wrought and cast austenitic SSs. Statistical models for estimating the fatigue lives of these steels in LWR environments have been updated with a larger data base. The significance of the effect of environment on the current Code design curve has been evaluated.
A miniature microcontroller curve tracing circuit for space flight testing transistors
NASA Astrophysics Data System (ADS)
Prokop, N.; Greer, L.; Krasowski, M.; Flatico, J.; Spina, D.
2015-02-01
This paper describes a novel miniature microcontroller based curve tracing circuit, which was designed to monitor the environmental effects on Silicon Carbide Junction Field Effect Transistor (SiC JFET) device performance, while exposed to the low earth orbit environment onboard the International Space Station (ISS) as a resident experiment on the 7th Materials on the International Space Station Experiment (MISSE7). Specifically, the microcontroller circuit was designed to operate autonomously and was flown on the external structure of the ISS for over a year. This curve tracing circuit is capable of measuring current vs. voltage (I-V) characteristics of transistors and diodes. The circuit is current limited for low current devices and is specifically designed to test high temperature, high drain-to-source resistance SiC JFETs. The results of each I-V data set are transmitted serially to an external telemetered communication interface. This paper discusses the circuit architecture, its design, and presents example results.
VizieR Online Data Catalog: Praesepe members light curves (Kovacs+, 2014)
NASA Astrophysics Data System (ADS)
Kovacs, G.; Hartman, J. D.; Bakos, G. A.; Quinn, S. N.; Penev, K.; Latham, D. W.; Bhatti, W.; Csubry, Z.; de Val-Borro, M.
2014-07-01
Light curves used in the time series analysis of Praesepe are presented. There are 381 light curves on instrumental Sloan r' magnitude scale with the zero points determined by the 2MASS magnitudes according to Eq. (1) of the paper. We present two types of magnitudes: a) external parameter decorrelated (EPD) and b), the ones obtained after the application of a trend filtering algorithm (TFA) on the EPD time series. These two methods are briefly described in the paper and in detail in the references therein. Here we just note that both methods are intended to filter out systematics due to environmental effects (instrumental, weather, etc.). For TFA filtering we used 600 templates and did not apply signal reconstruction. (5 data files).
Crack curving in a ductile pressurized fuselage
NASA Astrophysics Data System (ADS)
Lam, Paul W.
magnitude of CTOA and CTOD depends on the structural geometry, and including plasticity increases the crack tip displacements. An estimate of the strain in the skin flaps at the crack tip may indicate the tendency for flapping. Out-of-plane effects become significant as the crack propagates and curves.
Analysis of colloid and tracer breakthrough curves
NASA Astrophysics Data System (ADS)
Grindrod, Peter; Edwards, Mark S.; Higgo, Jenny J. W.; Williams, Geoffrey M.
1996-02-01
the flow regime). It is important to realize that even for unretarded species, an earlier peak in the breakthrough curve does not necessarily correspond to a faster mean elution rate, or vice versa. But rather that a colloid may elute faster but disperse less than an equivalent tracer. Hence its peak may be retarded compared to that of the tracer, even assuming no retardation. Hence one must consider a combination of mean elution rate and mean dispersion rate, and not rely on "peak times" to corroborate chromatographic effects. The importance of this lies in the fact that these processes are not independent and yet upscale differently. Thus realistic estimates of effective colloid dispersion rates should be upscaled in a way consistent with that adopted for tracers within the same system.
Shephard, M.S.; Dey, S.; Georges, M.K.
1995-12-31
Specific issues associated with the automatic generation of finite element meshes for curved geometric domains axe considered. A review of the definition of when a triangulation is a valid mesh, a geometric triangulation, for curved geometric domains is given. Consideration is then given to the additional operations necessary to maintain the validity of a mesh when curved finite elements are employed. A procedure to control the mesh gradations based on the curvature of the geometric model faces is also given.
Chopra, O. K.; Shack, W. J.; Energy Technology
2003-10-03
The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. The Code specifies fatigue design curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Existing fatigue strain-vs.-life ({var_epsilon}-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. This report provides an overview of the existing fatigue {var_epsilon}-N data for carbon and low-alloy steels and wrought and cast austenitic SSs to define the effects of key material, loading, and environmental parameters on the fatigue lives of the steels. Experimental data are presented on the effects of surface roughness on the fatigue life of these steels in air and LWR environments. Statistical models are presented for estimating the fatigue {var_epsilon}-N curves as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are discussed. Data available in the literature have been reviewed to evaluate the conservatism in the existing ASME Code fatigue evaluations. A critical review of the margins for ASME Code fatigue design curves is presented.
Thermal stability of curved ray tomography for corrosion monitoring
Willey, C. L.; Simonetti, F.; Nagy, P. B.; Instanes, G.
2014-02-18
Guided wave tomography is being developed as an effective tool for continuous monitoring of corrosion and erosion depth in pipelines. A pair of transmit- and receive-ring arrays of ultrasonic transducers encircles the pipe and delimits the section to be monitored. In curved ray tomography (CRT), the depth profile is estimated from the time delay matrix, Δτ, whose ij-th entry is the phase traveltime difference between the current and baseline signals measured between transducers i and j of the transmit and receive-ring arrays, respectively. Under perfectly stable experimental conditions, the non-zero entries of Δτ are only due to the occurrence of damage and provide a reliable input to CRT. However, during field operation, Δτ can develop non-zero entries due to a number of environmental changes ranging from temperature variations to degradation of transducer-pipe coupling and transducer intrinsic performance. Here, we demonstrate that these sources of instability can be eliminated by exploiting the spatial diversity of array measurements in conjunction with EMAT transducer technology which is intrinsically stable owing to its non-contact nature. The study is based on a full-scale experiment performed on a schedule 40, 8’ diameter, 3 m length steel pipe, monitored with two EMAT ring arrays. It is shown that for an irregularly shaped defect the proposed method yields maximum depth estimations that are as accurate as single point ultrasonic thickness gaging measurements and over a wide temperature range up to 175°C. The results indicate that advanced inversion schemes in combination with EMAT transduction offer great potential for continuously monitoring the progression of corrosion or erosion damage in the oil and gas industry.
Thermal stability of curved ray tomography for corrosion monitoring
NASA Astrophysics Data System (ADS)
Willey, C. L.; Simonetti, F.; Nagy, P. B.; Instanes, G.
2014-02-01
Guided wave tomography is being developed as an effective tool for continuous monitoring of corrosion and erosion depth in pipelines. A pair of transmit- and receive-ring arrays of ultrasonic transducers encircles the pipe and delimits the section to be monitored. In curved ray tomography (CRT), the depth profile is estimated from the time delay matrix, Δτ, whose ij-th entry is the phase traveltime difference between the current and baseline signals measured between transducers i and j of the transmit and receive-ring arrays, respectively. Under perfectly stable experimental conditions, the non-zero entries of Δτ are only due to the occurrence of damage and provide a reliable input to CRT. However, during field operation, Δτ can develop non-zero entries due to a number of environmental changes ranging from temperature variations to degradation of transducer-pipe coupling and transducer intrinsic performance. Here, we demonstrate that these sources of instability can be eliminated by exploiting the spatial diversity of array measurements in conjunction with EMAT transducer technology which is intrinsically stable owing to its non-contact nature. The study is based on a full-scale experiment performed on a schedule 40, 8' diameter, 3 m length steel pipe, monitored with two EMAT ring arrays. It is shown that for an irregularly shaped defect the proposed method yields maximum depth estimations that are as accurate as single point ultrasonic thickness gaging measurements and over a wide temperature range up to 175°C. The results indicate that advanced inversion schemes in combination with EMAT transduction offer great potential for continuously monitoring the progression of corrosion or erosion damage in the oil and gas industry.
Sediment concentration rating curves for a monsoonal climate: upper Blue Nile Basin
NASA Astrophysics Data System (ADS)
Moges, M. A.; Zemale, F. A.; Alemu, M. L.; Ayele, G. K.; Dagnew, D. C.; Tilahun, S. A.; Steenhuis, T. S.
2015-12-01
Information on sediment content in rivers is important for design of reservoirs and for environmental applications. Because of scarcity of continuous sediment data, methods have been developed to predict sediment loads based on few discontinuous measurements. Traditionally, loads are being predicted using rating curves that relate sediment load to discharge. The relationship assumes inherently a unique relationship between concentration and discharge and therefore although performing satisfactorily in predicting loads, it may be less suitable for predicting concentration. This is especially true in the Blue Nile basin of Ethiopia where concentrations decrease for a given discharge with the progression of the rainy monsoon phase. The objective of this paper is to improve the sediment concentration predictions throughout the monsoon period for the Ethiopian highlands with a modified rating type equation. To capture the observed sediment concentration pattern, we assume that the sediment concentration was at the transport limit early in the rainy season and then decrease linearly with effective rainfall towards source limited concentration. The modified concentration rating curve was calibrated for the four main rivers in the Lake Tana basin where sediment concentrations affect fish production and tourism. Then the scalability of the rating type equation was checked in three 100-ha watersheds for which historic data was available. The results show, that for predicting sediment concentrations, the (modified) concentration rating curve was more accurate than the (standard) load rating curve as expected. In addition loads were predicted more accurately for three of the four rivers. We expect that after more extensive testing over a wider geographical area, the proposed concentration rating curve will offer improved predictions of sediment concentrations in monsoonal climates.
Sediment concentration rating curves for a monsoonal climate: upper Blue Nile
NASA Astrophysics Data System (ADS)
Moges, Mamaru A.; Zemale, Fasikaw A.; Alemu, Muluken L.; Ayele, Getaneh K.; Dagnew, Dessalegn C.; Tilahun, Seifu A.; Steenhuis, Tammo S.
2016-07-01
Information on sediment concentration in rivers is important for design of reservoirs and for environmental applications. Because of the scarcity of continuous sediment data, methods have been developed to predict sediment loads based on few discontinuous measurements. Traditionally, loads are being predicted using rating curves that relate sediment load to discharge. The relationship assumes inherently a unique relationship between concentration and discharge and therefore although performing satisfactorily in predicting loads, it may be less suitable for predicting concentration. This is especially true in the Blue Nile Basin of Ethiopia where concentrations decrease for a given discharge with the progression of the rainy monsoon phase. The objective of this paper is to improve the sediment concentration predictions throughout the monsoon period for the Ethiopian highlands with a modified rating type equation. To capture the observed sediment concentration pattern, we assume that the sediment concentration was at the transport limit early in the rainy season and then decreases linearly with effective rainfall towards source-limited concentration. The modified concentration rating curve was calibrated for the four main rivers in the Lake Tana basin where sediment concentrations affect fish production and tourism. Then the scalability of the rating type equation was checked in three 100 ha watersheds for which historic data were available. The results show that for predicting sediment concentrations, the (modified) concentration rating curve was more accurate than the (standard) load rating curve as expected. In addition loads were predicted more accurately for three of the four rivers. We expect that after more extensive testing over a wider geographical area, the proposed concentration rating curve will offer improved predictions of sediment concentrations in monsoonal climates.
Ramifications of Hurwitz theory, KP integrability and quantum curves
NASA Astrophysics Data System (ADS)
Alexandrov, A.; Lewanski, D.; Shadrin, S.
2016-05-01
In this paper we revisit several recent results on monotone and strictly monotone Hurwitz numbers, providing new proofs. In particular, we use various versions of these numbers to discuss methods of derivation of quantum spectral curves from the point of view of KP integrability and derive new examples of quantum curves for the families of double Hurwitz numbers.
49 CFR 213.57 - Curves; elevation and speed limitations.
Code of Federal Regulations, 2013 CFR
2013-10-01
... operating speed for each curve is determined by the following formula— ER13MR13.007 Where— Vmax = Maximum... to this part is a table of speeds computed in accordance with the formula in paragraph (b) of this... type to operate at the desired curving speeds allowed under the formula in paragraph (b) of...
The Thermodynamic Functions in Curved Space of Neutron Star
NASA Astrophysics Data System (ADS)
Hussein, N. A.; Eisa, D. A.; Sayed, E. G.
2016-04-01
The aim of this article is to calculate the thermodynamic functions of a neutron star in curved space. We obtained equation of state (EOS) and the excess free energy for a neutron star in curved space up to order n4, where n is the density of particles.
No-till and curve numbers a closer look
Technology Transfer Automated Retrieval System (TEKTRAN)
Since its inception in the 1950s, worldwide adoption and use of the Curve Number (CN) methodology for estimating runoff has highlighted some inconsistencies, limitations and problems. Analysis of curve numbers derived from 34 years of rainfall-runoff data from a 2.7 ha Georgia Piedmont catchment man...
U-Shaped Curves in Development: A PDP Approach
ERIC Educational Resources Information Center
Rogers, Timothy T.; Rakison, David H.; McClelland, James L.
2004-01-01
As the articles in this issue attest, U-shaped curves in development have stimulated a wide spectrum of research across disparate task domains and age groups and have provoked a variety of ideas about their origins and theoretical significance. In the authors' view, the ubiquity of the general pattern suggests that U-shaped curves can arise from…
According to Jim: The Flawed Normal Curve of Intelligence
ERIC Educational Resources Information Center
Gallagher, James J.
2008-01-01
In this article, the author talks about the normal curve of intelligence which he thinks is flawed and contends that wrong conclusions have been drawn based on this spurious normal curve. An example is that of racial and ethnic differences wherein some authors maintain that some ethnic and racial groups are clearly superior to others based on…
Inequality by Design: Cracking the Bell Curve Myth [book review].
ERIC Educational Resources Information Center
Carroll, John B.
2002-01-01
This book, a critique of "The Bell Curve" by R. Herrnstein and C. Murray, explores what "inequality" in society means, how it arises, and how it can be measured or dealt with quantitatively. It also considers how societal and other variables work to increase or decrease inequality. The book argues that "The Bell Curve" vastly overestimates the…
Nonlinear Latent Curve Models for Multivariate Longitudinal Data
ERIC Educational Resources Information Center
Blozis, Shelley A.; Conger, Katherine J.; Harring, Jeffrey R.
2007-01-01
Latent curve models have become a useful approach to analyzing longitudinal data, due in part to their allowance of and emphasis on individual differences in features that describe change. Common applications of latent curve models in developmental studies rely on polynomial functions, such as linear or quadratic functions. Although useful for…
Three-Dimensional Interactive Design Using Bezier Curves and Surfaces.
ERIC Educational Resources Information Center
Khonsari, M. M.; Horn, D.
1987-01-01
Offers a method for interactive design of objects on a computer. Outlines a method which allows the designer to interact with orthogonal views to construct a three dimensional model of an arbitrary shape. Presents an algorithm based on the Bezier curves to efficiently create smooth curves and surfaces. (CW)
Hypothesis Generation in Latent Growth Curve Modeling Using Principal Components
ERIC Educational Resources Information Center
Davison, Mark L.
2008-01-01
While confirmatory latent growth curve analyses provide procedures for testing hypotheses about latent growth curves underlying data, one must first derive hypotheses to be tested. It is argued that such hypotheses should be generated from a combination of theory and exploratory data analyses. An exploratory components analysis is described and…
Regime Switching in the Latent Growth Curve Mixture Model
ERIC Educational Resources Information Center
Dolan, Conor V.; Schmittmann, Verena D.; Lubke, Gitta H.; Neale, Michael C.
2005-01-01
A linear latent growth curve mixture model is presented which includes switching between growth curves. Switching is accommodated by means of a Markov transition model. The model is formulated with switching as a highly constrained multivariate mixture model and is fitted using the freely available Mx program. The model is illustrated by analyzing…
Evaluating Latent Growth Curve Models Using Individual Fit Statistics
ERIC Educational Resources Information Center
Coffman, Donna L.; Millsap, Roger E.
2006-01-01
The usefulness of assessing individual fit in latent growth curve models was examined. The study used simulated data based on an unconditional and a conditional latent growth curve model with a linear component and a small quadratic component and a linear model was fit to the data. Then the overall fit of linear and quadratic models to these data…
New form of road/railway transition curve
Lipicnik, M.
1998-11-01
Road and railway transition curves have again become the subject of important scientific research and serious traffic engineering analyses because of high driving speeds and demands for automatic drive (i.e., car pilots). This article shows, in an original way, how to define or reconstruct the track of a vehicle when passing the elements of a continuous curve (straight lines, circles) so the track (curve) suits all requirements to which transition curves must be adapted. The praxis whereby a known mathematical curve (e.g., a cubic parabola, lemniscate, or chlotoid) was assumed as a transition curve and its suitability was analyzed has been passed over. On the basis of assumed kinematics models of the motion of a vehicle along joint alignment elements with a changing radius of curvature, the writers have analyzed different transition curves resulting in safe, comfortable, and economic driving. The curve resulting from a parabolic velocity chart of front wheel rotation during such movement which found the most suitable has been named POLUSA; a geometrical analysis of POLUSA has been performed and a manual for practical use completed.
Influence of pavement condition on horizontal curve safety.
Buddhavarapu, Prasad; Banerjee, Ambarish; Prozzi, Jorge A
2013-03-01
Crash statistics suggest that horizontal curves are the most vulnerable sites for crash occurrence. These crashes are often severe and many involve at least some level of injury due to the nature of the collisions. Ensuring the desired pavement surface condition is one potentially effective strategy to reduce the occurrence of severe accidents on horizontal curves. This study sought to develop crash injury severity models by integrating crash and pavement surface condition databases. It focuses on developing a causal relationship between pavement condition indices and severity level of crashes occurring on two-lane horizontal curves in Texas. In addition, it examines the suitability of the existing Skid Index for safety maintenance of two-lane curves. Significant correlation is evident between pavement condition and crash injury severity on two-lane undivided horizontal curves in Texas. Probability of a crash becoming fatal is appreciably sensitive to certain pavement indices. Data suggested that road facilities providing a smoother and more comfortable ride are vulnerable to severe crashes on horizontal curves. In addition, the study found that longitudinal skid measurement barely correlates with injury severity of crashes occurring on curved portions. The study recommends exploring the option of incorporating lateral friction measurement into Pavement Management System (PMS) databases specifically at curved road segments. PMID:23298704
Model tracks sediment dynamics for highly curved meandering rivers
NASA Astrophysics Data System (ADS)
Schultz, Colin
2013-07-01
Understanding the dynamics of meandering rivers—the twisting, turning, and wandering of waterways over time—is of concern to water managers and civil engineers. How curved a river is affects how it moves, and Ottevanger et al. built on existing models to improve representations of meandering dynamics for highly curved rivers.
Ahead of the Curve. Future Shifts in Higher Education
ERIC Educational Resources Information Center
Jackson, Shirley Ann
2005-01-01
It used to be that physicians stayed "ahead of the curve" with new research in their secialties by reading medical journal articles. Yet medical literature databases today house more than 10 million abstracts and are adding 7,000 to 8,000 more each week. Staying ahead of the curve is thus impossible for any single individual to manage. Further,…
Light curve demography via Bayesian functional data analysis
NASA Astrophysics Data System (ADS)
Loredo, Thomas; Budavari, Tamas; Hendry, Martin A.; Kowal, Daniel; Ruppert, David
2015-08-01
Synoptic time-domain surveys provide astronomers, not simply more data, but a different kind of data: large ensembles of multivariate, irregularly and asynchronously sampled light curves. We describe a statistical framework for light curve demography—optimal accumulation and extraction of information, not only along individual light curves as conventional methods do, but also across large ensembles of related light curves. We build the framework using tools from functional data analysis (FDA), a rapidly growing area of statistics that addresses inference from datasets that sample ensembles of related functions. Our Bayesian FDA framework builds hierarchical models that describe light curve ensembles using multiple levels of randomness: upper levels describe the source population, and lower levels describe the observation process, including measurement errors and selection effects. Schematically, a particular object's light curve is modeled as the sum of a parameterized template component (modeling population-averaged behavior) and a peculiar component (modeling variability across the population), subsequently subjected to an observation model. A functional shrinkage adjustment to individual light curves emerges—an adaptive, functional generalization of the kind of adjustments made for Eddington or Malmquist bias in single-epoch photometric surveys. We are applying the framework to a variety of problems in synoptic time-domain survey astronomy, including optimal detection of weak sources in multi-epoch data, and improved estimation of Cepheid variable star luminosities from detailed demographic modeling of ensembles of Cepheid light curves.
Implementation Learning and Forgetting Curve to Scheduling in Garment Industry
NASA Astrophysics Data System (ADS)
Muhamad Badri, Huda; Deros, Baba Md; Syahri, M.; Saleh, Chairul; Fitria, Aninda
2016-02-01
The learning curve shows the relationship between time and the cumulative number of units produced which using the mathematical description on the performance of workers in performing repetitive works. The problems of this study is level differences in the labors performance before and after the break which affects the company's production scheduling. The study was conducted in the garment industry, which the aims is to predict the company production scheduling using the learning curve and forgetting curve. By implementing the learning curve and forgetting curve, this paper contributes in improving the labors performance that is in line with the increase in maximum output 3 hours productive before the break are 15 unit product with learning curve percentage in the company is 93.24%. Meanwhile, the forgetting curve improving maximum output 3 hours productive after the break are 11 unit product with the percentage of forgetting curve in the company is 92.96%. Then, the obtained 26 units product on the productive hours one working day is used as the basic for production scheduling.
13. PULL CURVE RECONSTRUCTION: Photocopy of a September 1907 photograph ...
13. PULL CURVE RECONSTRUCTION: Photocopy of a September 1907 photograph showing the reconstruction of a pull curve at Sacramento and Larkin Streets following the earthquake and fire. The tracks belong to United Railroads of San Francisco. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco, San Francisco County, CA
49 CFR 213.57 - Curves; elevation and speed limitations.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 49 Transportation 4 2012-10-01 2012-10-01 false Curves; elevation and speed limitations. 213.57 Section 213.57 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Geometry § 213.57 Curves; elevation and speed limitations. (a) The...
Compound complex curves: the authentic geometry of esthetic dentistry.
Scoble, Han O; White, Shane N
2014-06-01
Observers are drawn to the intricate and unpredictable way light reflects off the compound complex curved surfaces seen in nature, art, and industry. Teeth are no exception, containing as they do such detail in their gross anatomy, fine anatomic detail, and surface texture. Compound complex curves are particularly important when engineered materials are used to mimic naturally occurring objects, including prosthetic teeth, and they can provide both authenticity and beauty. The purpose of this article was to describe the nature of compound complex curves, their historical context, and their importance in creating natural-looking prostheses. Classically, such curves have been described by using descriptive qualitative methods or quantitative mathematical methods; now these approaches merge. Natural tooth anatomy contains interlinked features at different levels of scale from gross to fine surface texture detail. These curves should be created appropriately for individual restorative treatments. PMID:24589121
Simplified curve fits for the transport properties of equilibrium air
NASA Technical Reports Server (NTRS)
Srinivasan, S.; Tannehill, J. C.
1987-01-01
New, improved curve fits for the transport properties of equilibruim air have been developed. The curve fits are for viscosity and Prandtl number as functions of temperature and density, and viscosity and thermal conductivity as functions of internal energy and density. The curve fits were constructed using grabau-type transition functions to model the tranport properties of Peng and Pindroh. The resulting curve fits are sufficiently accurate and self-contained so that they can be readily incorporated into new or existing computational fluid dynamics codes. The range of validity of the new curve fits are temperatures up to 15,000 K densities from 10 to the -5 to 10 amagats (rho/rho sub o).
DEB: definite error bounded tangent estimator for digital curves.
Prasad, Dilip K; Leung, Maylor K H; Quek, Chai; Brown, Michael S
2014-10-01
We propose a simple and fast method for tangent estimation of digital curves. This geometric-based method uses a small local region for tangent estimation and has a definite upper bound error for continuous as well as digital conics, i.e., circles, ellipses, parabolas, and hyperbolas. Explicit expressions of the upper bounds for continuous and digitized curves are derived, which can also be applied to nonconic curves. Our approach is benchmarked against 72 contemporary tangent estimation methods and demonstrates good performance for conic, nonconic, and noisy curves. In addition, we demonstrate a good multigrid and isotropic performance and low computational complexity of O(1) and better performance than most methods in terms of maximum and average errors in tangent computation for a large variety of digital curves. PMID:25122569
P-curve: a key to the file-drawer.
Simonsohn, Uri; Nelson, Leif D; Simmons, Joseph P
2014-04-01
Because scientists tend to report only studies (publication bias) or analyses (p-hacking) that "work," readers must ask, "Are these effects true, or do they merely reflect selective reporting?" We introduce p-curve as a way to answer this question. P-curve is the distribution of statistically significant p values for a set of studies (ps < .05). Because only true effects are expected to generate right-skewed p-curves-containing more low (.01s) than high (.04s) significant p values--only right-skewed p--curves are diagnostic of evidential value. By telling us whether we can rule out selective reporting as the sole explanation for a set of findings, p-curve offers a solution to the age-old inferential problems caused by file-drawers of failed studies and analyses. PMID:23855496
Estimating the R-curve from residual strength data
NASA Technical Reports Server (NTRS)
Orange, T. W.
1985-01-01
A method is presented for estimating the crack-extension resistance curve (R-curve) from residual-strength (maximum load against original crack length) data for precracked fracture specimens. The method allows additional information to be inferred from simple test results, and that information can be used to estimate the failure loads of more complicated structures of the same material and thickness. The fundamentals of the R-curve concept are reviewed first. Then the analytical basis for the estimation method is presented. The estimation method has been verified in two ways. Data from the literature (involving several materials and different types of specimens) are used to show that the estimated R-curve is in good agreement with the measured R-curve. A recent predictive blind round-robin program offers a more crucial test. When the actual failure loads are disclosed, the predictions are found to be in good agreement.
Curved mesh generation and mesh refinement using Lagrangian solid mechanics
Persson, P.-O.; Peraire, J.
2008-12-31
We propose a method for generating well-shaped curved unstructured meshes using a nonlinear elasticity analogy. The geometry of the domain to be meshed is represented as an elastic solid. The undeformed geometry is the initial mesh of linear triangular or tetrahedral elements. The external loading results from prescribing a boundary displacement to be that of the curved geometry, and the final configuration is determined by solving for the equilibrium configuration. The deformations are represented using piecewise polynomials within each element of the original mesh. When the mesh is sufficiently fine to resolve the solid deformation, this method guarantees non-intersecting elements even for highly distorted or anisotropic initial meshes. We describe the method and the solution procedures, and we show a number of examples of two and three dimensional simplex meshes with curved boundaries. We also demonstrate how to use the technique for local refinement of non-curved meshes in the presence of curved boundaries.
New Data for the Mesoamerican Directional Secular Variation Curve
NASA Astrophysics Data System (ADS)
Soler-Arechalde, A. M.
2015-12-01
The Mesoamerican direction secular variation curve is an endless project, new data has been incorporated each year. The new data have radiocarbon dates associated. Wolfman in 1990 proposed the First Curve of Mesoamerica from 1 to 1200 DC. Since 2000 the UNAM´s Archaeomagnetism team has been working continuously by sampling 9 new sites and resampling new stages of Teotihuacan, Teopancazco and Tula. As a result of these investigations more than 70 new data has been annexed and the curve grows until 1600 DC. Data from El Tejar and DuBois has allowed to expand the curve until 1200 BC. An analysis of the incorporation of these new data is presented and the resultant curve is compared to the ARCH3K model.
Shape and Individual Variability of the Blur Adaptation Curve
Vera-Diaz, Fuensanta A.; Woods, Russell L.; Peli, Eli
2010-01-01
We are interested in clinical implications of adaptation to blurred and sharpened images. Therefore, we investigated repeatability, individual variability and characteristics of the adaptation curves in normally-sighted individuals (n=39). The point of subjective neutrality (PSN – the slope of the spatial spectrum of the image that appears normal) following adaptation was measured for each adaptation level and was used to derive individual adaptation curves for each subject. Adaptation curves were fitted with a modified Tukey biweight function as the curves were found to be tumbled-S shaped and asymmetrical for blur and sharp in some subjects. The adaptation curve was found to be an individual characteristic as inter-subject variability exceeds test-retest variability. The existence of individual variability may have implications for the prescription and clinical success of optical devices as well as image enhancement rehabilitation options. PMID:20417657
Developing Novel Reservoir Rule Curves Using Seasonal Inflow Projections
NASA Astrophysics Data System (ADS)
Tseng, Hsin-yi; Tung, Ching-pin
2015-04-01
Due to significant seasonal rainfall variations, reservoirs and their flexible operational rules are indispensable to Taiwan. Furthermore, with the intensifying impacts of climate change on extreme climate, the frequency of droughts in Taiwan has been increasing in recent years. Drought is a creeping phenomenon, the slow onset character of drought makes it difficult to detect at an early stage, and causes delays on making the best decision of allocating water. For these reasons, novel reservoir rule curves using projected seasonal streamflow are proposed in this study, which can potentially reduce the adverse effects of drought. This study dedicated establishing new rule curves which consider both current available storage and anticipated monthly inflows with leading time of two months to reduce the risk of water shortage. The monthly inflows are projected based on the seasonal climate forecasts from Central Weather Bureau (CWB), which a weather generation model is used to produce daily weather data for the hydrological component of the GWLF. To incorporate future monthly inflow projections into rule curves, this study designs a decision flow index which is a linear combination of current available storage and inflow projections with leading time of 2 months. By optimizing linear relationship coefficients of decision flow index, the shape of rule curves and the percent of water supply in each zone, the best rule curves to decrease water shortage risk and impacts can be developed. The Shimen Reservoir in the northern Taiwan is used as a case study to demonstrate the proposed method. Existing rule curves (M5 curves) of Shimen Reservoir are compared with two cases of new rule curves, including hindcast simulations and historic seasonal forecasts. The results show new rule curves can decrease the total water shortage ratio, and in addition, it can also allocate shortage amount to preceding months to avoid extreme shortage events. Even though some uncertainties in
How To Reduce the Laparoscopic Colorectal Learning Curve
Sánchez Gonzalez, Javier; Blanco Antona, Francisco; Martín Esteban, Maria Luz; Colao García, Laura; Cuevas Gonzalez, Jorge; Mayo Iscar, Agustin; Blanco Alvarez, Jose Ignacio; Martín del Olmo, Juan Carlos
2014-01-01
Background: The laparoscopic approach for colorectal pathologies is becoming more widely used, and surgeons have had to learn how to perform this new technique. The purpose of this work is to study the indicators of the learning curve for laparoscopic colectomy in a community hospital and to find when the group begins to improve. Methodology: From January 1 2005 to December 31 2012, 313 consecutive laparoscopic colorectal surgeries were performed (105 rectal and 208 colonic) by at least 60% of the same surgical team (6 members) in each operation. We evaluate the learning curve by moving averages and cumulative sums (CUSUM) for different variables related to the surgery outcomes. Results: Moving average curves for postoperative stay, fasting, and second step analgesia show a stabilizing trend toward improvement as we get more experience. However, intensive care unit stay, number of lymph nodes achieved, and operating time did not show a clear decreasing tendency. CUSUM curves of conversion, specimens <12 lymph nodes, and complications all show a clear turning point marked on all the charts around the procedure 60, accumulating a positive trend toward improvement. The CUSUM curve of the “learning variable” shows this improvement point at procedure 70. Conclusions: The laparoscopic colectomy learning curve accelerates with a collective team involvement in each procedure. The CUSUM and moving average curves are useful for initial and ongoing monitoring of new surgical procedures. The markers of the learning curve evidenced in our study are the conversion rate, postoperative surgical morbidity, and the number of patients with a lymph node count <12. What is new in this paper? The significance of this study is the evaluation of the learning curve, in laparoscopic colorectal surgery, of a surgical team in a community hospital, using moving average and CUSUM curves. This study demonstrated that the number of patients needed to achieve skilful practice decreased when
Black, D.G.
1995-06-01
This section of the 1994 Hanford Site Environmental Report summarizes the onsite and offsite releases of radioactive and regulated materials. The specific agencies notified of the releases depended on the type, amount, and location of the individual occurrences. The more significant of these off-normal environmental occurrences are summarized in this section.
ERIC Educational Resources Information Center
Lott, Jesse; Allen, Rodney F.
This booklet, a general guide to citizen eco-action, discusses a plan of action on community environmental problems. It offers factors to be considered in any community eco-action situation, but it is not a rigid set of rules. An overview identifies seven key ideas of environmental issues, including the universal participation of all humans in the…
... Some environmental risks are a part of the natural world, like radon in the soil. Others are the result of human activities, like lead poisoning from paint, or exposure to asbestos or mercury from mining or industrial use. NIH: National Institute of Environmental Health Sciences
ERIC Educational Resources Information Center
Rowell, Elizabeth H.; Goodkind, Thomas B.
1989-01-01
Analyzes editorial cartoons from 1972-87 to determine extent and type of attention to environmental issues. Explores cartoons' direct and indirect messages regarding outdoors. Describes cartoons about energy, environment, pollution, space. Discusses artists' use of animals, vegetation, and outdoor activities. Identifies environmental issues as…
Corporate environmentalism and environmental innovation.
Chang, Ching-Hsing; Sam, Abdoul G
2015-04-15
Several papers have explored the effect of tighter environmental standards on environmental innovation. While mandatory regulation remains the central tenet of US environmental policy, the regulatory landscape has changed since the early 1990s with the increased recourse by federal and state agencies to corporate environmentalism--voluntary pollution prevention (P2) by firms--to achieve environmental improvements. We therefore estimate the effects of voluntary P2 activities on the patenting of environmental technologies by a sample of manufacturing firms. With our panel data of 352 firms over the 1991-2000 period, we adopt an instrumental variable Poisson framework to account for the count nature of patents and the endogeneity of the P2 adoption decision. Our results indicate that the adoption of voluntary P2 activities in the manufacturing sector has led to a statistically and economically significant increase in the number of environmental patents, suggesting that corporate environmentalism can act as a catalyst for investments in cleaner technologies. Our findings are internationally relevant given the increasing ubiquity of corporate environmentalism in both developed and developing economies. PMID:25687809
Lynch, D R; Hutchinson, C E
1992-01-01
The need for a new profession devoted to environmental matters is asserted. The qualities of such a profession are sketched, and it is argued that new initiatives in environmental education are needed in the form of graduate, professional programs with primary emphasis on practice. An example 2-year program is presented. A fundamental requirement is scientific competence; undergraduate preparation in the sciences or engineering is mandatory. The graduate curriculum itself is built on three primary cores: environmental science and engineering, business and management, and public policy. Additionally, an environmental round table is proposed as a focal point for academic, industrial, governmental, and public discussion on environmental matters. The round table would provide oversight for the professional educational program and an affiliated research institute. PMID:11607268
Code of Federal Regulations, 2011 CFR
2011-01-01
... information for skip lot sampling and inspection. EC02SE91.019 Notes: 1. This curve applies only to the specific skip lot sampling and inspection plan described in § 42.121 and § 42.123. 2. Pa and Pas are...) curve information for skip lot sampling and inspection. 42.142 Section 42.142 Agriculture Regulations...
Knowledge fusion: Comparison of fuzzy curve smoothers to statistically motivated curve smoothers
Burr, T.; Strittmatter, R.B.
1996-03-01
This report describes work during FY 95 that was sponsored by the Department of Energy, Office of Nonproliferation and National Security (NN) Knowledge Fusion (KF) Project. The project team selected satellite sensor data to use as the one main example to which its analysis algorithms would be applied. The specific sensor-fusion problem has many generic features, which make it a worthwhile problem to attempt to solve in a general way. The generic problem is to recognize events of interest from multiple time series that define a possibly noisy background. By implementing a suite of time series modeling and forecasting methods and using well-chosen alarm criteria, we reduce the number of false alarms. We then further reduce the number of false alarms by analyzing all suspicious sections of data, as judged by the alarm criteria, with pattern recognition methods. This report gives a detailed comparison of two of the forecasting methods (fuzzy forecaster and statistically motivated curve smoothers as forecasters). The two methods are compared on five simulated and five real data sets. One of the five real data sets is satellite sensor data. The conclusion is the statistically motivated curve smoother is superior on simulated data of the type we studied. The statistically motivated method is also superior on most real data. In defense of the fuzzy-logic motivated methods, we point out that fuzzy-logic methods were never intended to compete with statistical methods on numeric data. Fuzzy logic was developed to handle real-world situations where either real data was not available or was supplemented with either ``expert opinion`` or some sort of linguistic information.
What Do Reported Learning Curves Mean for Orthopaedic Surgeons?
Gofton, Wade T; Solomon, Michael; Gofton, Tyson; Pagé, Alex; Kim, Paul R; Netting, Caleb; Bhandari, Mohit; Beaulé, Paul E
2016-01-01
Practicing orthopaedic surgeons must assess the effects of the learning curve on patient safety and surgical outcomes if a new implant, technique, or approach is being considered; however, it remains unclear how learning curves reported in the literature should be interpreted and to what extent their results can be generalized. Learning curve reports from other surgical specialties and from orthopaedic surgery can be analyzed to identify the strengths and weaknesses of learning curve reporting. Single-surgeon series and registry data can be analyzed to understand learning challenges and to develop a personalized learning plan. Learning curve reports from single-surgeon series have several limitations that result from the limited dataset reported and inconsistencies in the way data are reported. Conversely, learning curve reports from registry data are likely to have greater generalizability, but are largely beneficial retrospectively, after data from a sufficient number of surgeons are assessed. There is a pressing need for surgeons to develop improved and consistent standards for learning curve reporting. Although registry data may provide better prospective measures in the future, the implementation of such registries faces several challenges. Despite substantial limitations, single-surgeon series remain the most effective way for practicing surgeons to assess their learning challenge and develop an appropriate learning plan. PMID:27049229
Progress Report on Alloy 617 Isochronous Stress-Strain Curves
Jill K. Wright; Richard N. Wright; Nancy J. Lybeck
2014-03-01
Isochronous stress-strain curves for Alloy 617 up to a temperature of 1000°C will be required to qualify the material for elevated temperature design in Section III, Division 1, Subsection NH of the ASME Boiler and Pressure Vessel Code. Several potential methods for developing these curves are reviewed in this report. It is shown that in general power-law creep is the rate controlling deformation mechanism for a wide range of alloy heats, test temperatures and stresses. Measurement of the strain rate sensitivity of Alloy 617 indicates that the material is highly strain rate sensitive in the tensile deformation range above about 750°C. This suggests that the concept of a hot tensile curve as a bounding case on the isochronous stress-strain diagrams is problematic. The impact of strain rate on the hot tensile curves is examined and it is concluded that incorporating such a curve is only meaningful if a single tensile strain rate (typically the ASTM standard rate of 0.5%/min) is arbitrarily defined. Current experimentally determined creep data are compared to isochronous stress-strain curves proposed previously by the German programs in the 1980s and by the 1990 draft ASME Code Case. Variability in how well the experimental data are represented by the proposed design curves that suggests further analysis is necessary prior to completing a new draft Code Case.
Simplified curve fits for the thermodynamic properties of equilibrium air
NASA Technical Reports Server (NTRS)
Srinivasan, S.; Tannehill, J. C.; Weilmuenster, K. J.
1986-01-01
New improved curve fits for the thermodynamic properties of equilibrium air were developed. The curve fits are for p = p(e,rho), a = a(e,rho), T = T(e,rho), s = s(e,rho), T = T(p,rho), h = h(p,rho), rho = rho(p,s), e = e(p,s) and a = a(p,s). These curve fits can be readily incorporated into new or existing Computational Fluid Dynamics (CFD) codes if real-gas effects are desired. The curve fits were constructed using Grabau-type transition functions to model the thermodynamic surfaces in a piecewise manner. The accuracies and continuity of these curve fits are substantially improved over those of previous curve fits appearing in NASA CR-2470. These improvements were due to the incorporation of a small number of additional terms in the approximating polynomials and careful choices of the transition functions. The ranges of validity of the new curve fits are temperatures up to 25,000 K and densities from 10 to the minus 7th to 100 amagats (rho/rho sub 0).
Cepheid light curve demography via Bayesian functional data analysis
NASA Astrophysics Data System (ADS)
Loredo, Thomas J.; Hendry, Martin; Kowal, Daniel; Ruppert, David
2016-01-01
Synoptic time-domain surveys provide astronomers, not simply more data, but a different kind of data: large ensembles of multivariate, irregularly and asynchronously sampled light curves. We describe a statistical framework for light curve demography—optimal accumulation and extraction of information, not only along individual light curves as conventional methods do, but also across large ensembles of related light curves. We build the framework using tools from functional data analysis (FDA), a rapidly growing area of statistics that addresses inference from datasets that sample ensembles of related functions. Our Bayesian FDA framework builds hierarchical models that describe light curve ensembles using multiple levels of randomness: upper levels describe the source population, and lower levels describe the observation process, including measurement errors and selection effects. Roughly speaking, a particular object's light curve is modeled as the sum of a parameterized template component (modeling population-averaged behavior) and a peculiar component (modeling variability across the population), subsequently subjected to an observation model. A functional shrinkage adjustment to individual light curves emerges—an adaptive, functional generalization of the kind of adjustments made for Eddington or Malmquist bias in single-epoch photometric surveys. We describe ongoing work applying the framework to improved estimation of Cepheid variable star luminosities via FDA-based refinement and generalization of the Cepheid period-luminosity relation.
How do the extinction curves in galaxies evolve?
NASA Astrophysics Data System (ADS)
Asano, R.; Takeuchi, T.; Hirashita, H.; Nozawa, T.
We investigate the evolution of extinction curves in galaxies based on our evolution model of grain size distribution. In this model, we considered various processes: dust formation by SNe II and AGB stars, dust destruction by SN shocks in the interstellar medium (ISM), metal accretion onto the surface of grains, shattering and coagulation. We find that the extinction curve is flat in the earliest stage of galaxy evolution because the grain size distribution is dominated by large (a & 0.1 µ m, where a is the grain radius) grains produced by stars. As the galaxy is enriched with dust, shattering becomes effective to produce a large abundance of small grains (a . 0.01 µ m). Then, the total surface area of grains per grain mass becomes large, and grain growth becomes effective at small grain radii, forming a bump at a ˜ 10-3 -10-2 µ m on the grain size distribution. Consequently, the extinction curve at ultraviolet (UV) wavelengths becomes steep, and a bump at 1/λ ˜ 4.5 µ m-1 (λ : wavelength) on the extinction curve becomes prominent. The galactic age when the extinction curve has the bump is roughly estimated as t ˜ (τSF /Gyr)1/2 Gyr, where τSF is the star formation timescale. Once coagulation becomes effective, the extinction curves become flatter, but the UV extinction remains overproduced when compared with the Milky Way extinction curve. This discrepancy can be resolved by introducing a stronger contribution of coagulation. Thus, an interplay between shattering and coagulation could be important to reproduce the Milky Way extinction curve. We conclude that the extinction curves of galaxies change drastically through the galaxy lifetime because the main dust processes that contribute to the grain size distribution change.
Curve fitting for RHB Islamic Bank annual net profit
NASA Astrophysics Data System (ADS)
Nadarajan, Dineswary; Noor, Noor Fadiya Mohd
2015-05-01
The RHB Islamic Bank net profit data are obtained from 2004 to 2012. Curve fitting is done by assuming the data are exact or experimental due to smoothing process. Higher order Lagrange polynomial and cubic spline with curve fitting procedure are constructed using Maple software. Normality test is performed to check the data adequacy. Regression analysis with curve estimation is conducted in SPSS environment. All the eleven models are found to be acceptable at 10% significant level of ANOVA. Residual error and absolute relative true error are calculated and compared. The optimal model based on the minimum average error is proposed.
Integrable mappings of the plane preserving biquadratic invariant curves II
NASA Astrophysics Data System (ADS)
Iatrou, Apostolos; Roberts, John A. G.
2002-03-01
We review recently introduced curve-dependent McMillan maps which are mappings of the plane that preserve biquadratic foliations. We show that they are measure preserving and thus integrable. We discuss the geometry of these maps including their fixed points and their stability. We consider the normal forms of symmetric and asymmetric biquadratic curves and the normal forms for their associated McMillan maps. We further discuss the dynamics on biquadratic curves by considering the possibility of parametrizing them by Jacobian elliptic or rational functions.
Asteroid Shape and Spin Axis Modeling Via Light Curve Inversion
NASA Astrophysics Data System (ADS)
Friz, Paul; Gokhale, V.
2013-01-01
We present light curves and shape and spin axis models for the five asteroids: 291 Alice, 281 Lucretia, 321 Florentina, 714 Ulula, and 3169 Ostro. These models were obtained using data taken from the Truman Observatory, the Asteroid Photometric Catalogue, and the Minor Planet Center. Knowledge of individual asteroids shapes and spin axes is vital to understanding the solar system. However, currently only 213 out of the 500,000 asteroids with known orbits have been modeled. By taking many light curves of asteroids over several apparitions it is possible to determine their shapes and spin axes by a process known as light curve inversion.
Cluster speckle structures through multiple apertures forming a closed curve
NASA Astrophysics Data System (ADS)
Mosso, E.; Tebaldi, M.; Lencina, A.; Bolognini, N.
2010-04-01
In this work, cluster-like speckle patterns are analyzed. These patterns are generated when a diffuser illuminated by coherent light is imaged by a lens having a pupil mask with multiple apertures forming a closed curve. We show that the cluster structure results from the complex modulation produced inside each speckle which is generated by multiple interferences of light through the apertures. In particular, when the apertures are uniformly distributed along a closed curve, the resulting image speckle cluster replicates the pupil aperture distribution. Experimental results and theoretical simulations show that cluster features depend on the apertures distribution and the size of the closed curves.
Using Kepler Light Curves for Astronomy Education and Public Outreach
NASA Astrophysics Data System (ADS)
Cash, Jennifer; Rivers, S.; Eleby, J.; Gould, A.; Komatsu, T.
2014-01-01
We will present our efforts related to Education and Public Outreach activities using Kepler Light Curves. We are currently developing interactive web based activities to introduce the public to the general topic of Stellar Variability and Intrinsic Variable Stars in particular using the high quality light curves of over a dozen Kepler targets. Along with the public website, we are exploring areas to develop teacher guides to use Kepler Light Curves in the middle and high school classrooms. These efforts are supported through a NASA EPSCoR grant "South Carolina Joint Venture Program" via a subaward to SC State University.
Quaternion wave equations in curved space-time
NASA Technical Reports Server (NTRS)
Edmonds, J. D., Jr.
1974-01-01
The quaternion formulation of relativistic quantum theory is extended to include curvilinear coordinates and curved space-time in order to provide a framework for a unified quantum/gravity theory. Six basic quaternion fields are identified in curved space-time, the four-vector basis quaternions are identified, and the necessary covariant derivatives are obtained. Invariant field equations are derived, and a general invertable coordinate transformation is developed. The results yield a way of writing quaternion wave equations in curvilinear coordinates and curved space-time as well as a natural framework for solving the problem of second quantization for gravity.
Electromagnetic characteristics of Hilbert curve-based metamaterials
NASA Astrophysics Data System (ADS)
Chen, Ruirui; Li, Sucheng; Gu, Chendong; Anwar, Shahzad; Hou, Bo; Lai, Yun
2014-08-01
As the typical building blocks of metamaterials, the cut wire and the split ring resonator have been extensively studied in recent years. Besides them, the space-filling curve-based metamaterials are receiving great attentions because of their intrinsic subwavelength and multi-bands characteristics. In this work, we have investigated experimentally and numerically the electromagnetic characteristics of such Hilbert curve metamaterial in the microwave frequency regime and found a deeply subwavelength magnetic resonance supported by the fractal pattern and featuring the wavelength-to-size ratio more than 20. The subwavelength electromagnetic properties of the Hilbert curve will be beneficial to realize high-performance metamaterials.
The extended polar writhe: a tool for open curves mechanics
NASA Astrophysics Data System (ADS)
Prior, Christopher B.; Neukirch, Sébastien
2016-05-01
A measure of the writhing of a curve is introduced and is used to extend the Călugăreanu decomposition for closed curves, as well as the polar decomposition for curves bound between planes. The new writhe measure is also shown to be able to assess changes in linking due to belt-trick and knotting type deformations, and further its utility is illustrated on examples taken from elastic rod parameter-continuation studies. Finally C++ and mathematica codes are made available and shown to be faster than existing algorithms for the numerical computation of the writhe.
Exhaustive search system and method using space-filling curves
Spires, Shannon V.
2003-10-21
A search system and method for one agent or for multiple agents using a space-filling curve provides a way to control one or more agents to cover an area of any space of any dimensionality using an exhaustive search pattern. An example of the space-filling curve is a Hilbert curve. The search area can be a physical geography, a cyberspace search area, or an area searchable by computing resources. The search agent can be one or more physical agents, such as a robot, and can be software agents for searching cyberspace.
New Light Curves and Orbital Solution for AM Leonis
NASA Astrophysics Data System (ADS)
Hiller, Mary E.; Osborn, Wayne; Terrell, Dirk
2004-04-01
New UBVRI photometry has been obtained for the W UMa eclipsing system AM Leonis. The data have been used to derive nine times of minimum and to construct light curves. The minimum timings show that the system recently had a significant period increase. Modeling of the light curves shows AM Leo to be an overcontact system with a mass ratio of 2.51. Both Rucinski & Duerbeck's absolute magnitude calibration for W UMa stars applied to our photometry and the radial velocity curve combined with our derived parameters indicate a distance near 125 pc, larger than the 77 pc from the Hipparcos parallax.
Real-Time Exponential Curve Fits Using Discrete Calculus
NASA Technical Reports Server (NTRS)
Rowe, Geoffrey
2010-01-01
An improved solution for curve fitting data to an exponential equation (y = Ae(exp Bt) + C) has been developed. This improvement is in four areas -- speed, stability, determinant processing time, and the removal of limits. The solution presented avoids iterative techniques and their stability errors by using three mathematical ideas: discrete calculus, a special relationship (be tween exponential curves and the Mean Value Theorem for Derivatives), and a simple linear curve fit algorithm. This method can also be applied to fitting data to the general power law equation y = Ax(exp B) + C and the general geometric growth equation y = Ak(exp Bt) + C.
Electromagnetic propagation in PEC and absorbing curved S-ducts
NASA Technical Reports Server (NTRS)
Baumeister, Kenneth J.
1988-01-01
A finite-element Galerkin formulation has been developed to study transverse magnetic (TM) wave propagation in 2-D S-curved ducts with both perfectly conducting and absorbing walls. The reflection and transmission at the entrances and the exits of the curved ducts are determined by coupling the finite-element solutions in the curved ducts to the eigenfunctions of an infinite, uniform, perfectly conducting duct. Example solutions are presented for a double mitred and S-ducts of various lengths. The length of the S-duct is found to significantly effect the reflective characteristics of the duct. Also, the effect of curvature on an absorbing duct is illustrated.
On Slater's criterion for the breakup of invariant curves
NASA Astrophysics Data System (ADS)
Abud, C. V.; Caldas, I. L.
2015-07-01
We numerically explore Slater's theorem in the context of dynamical systems to study the breakup of invariant curves. Slater's theorem states that an irrational translation over a circle returns to an arbitrary interval in at most three different recurrence times expressible by the continued fraction expansion of the related irrational number. The hypothesis considered in this paper is that Slater's theorem can be also verified in the dynamics of invariant curves. Hence, we use Slater's theorem to develop a qualitative and quantitative numerical approach to determine the breakup of invariant curves in the phase space of area-preserving maps.
Bolometric and UV light curves of core-collapse supernovae
Pritchard, T. A.; Roming, P. W. A.; Brown, Peter J.; Bayless, Amanda J.; Frey, Lucille H.
2014-06-01
The Swift UV-Optical Telescope (UVOT) has been observing core-collapse supernovae (CCSNe) of all subtypes in the UV and optical since 2005. Here we present 50 CCSNe observed with the Swift UVOT, analyzing their UV properties and behavior. Where we have multiple UV detections in all three UV filters (λ {sub c} = 1928-2600 Å), we generate early time bolometric light curves, analyze the properties of these light curves and the UV contribution to them, and derive empirical corrections for the UV-flux contribution to optical-IR based bolometric light curves.
QUEST1 VARIABILITY SURVEY. III. LIGHT CURVE CATALOG UPDATE
Rengstorf, A. W.; Thompson, D. L.; Mufson, S. L.; Honeycutt, R. K.; Adams, B.; Baltay, C.; Gebhard, M.; Andrews, P.; Coppi, P.; Emmet, W.; Vivas, A. K.; Abad, C.; Bongiovanni, A.; Briceno, C.; Bruzual, G.; Prugna, F. Della; Hernandez, J.; Bailyn, C.; Ferrin, I.; Fuenmayor, F.
2009-03-15
This paper reports an update to the QUEST1 (QUasar Equatorial Survey Team, Phase 1) Variability Survey (QVS) light curve catalog, which links QVS instrumental magnitude light curves to Sloan Digital Sky Survey (SDSS) objects and photometry. In the time since the original QVS catalog release, the overlap between publicly available SDSS data and QVS data has increased by 8% in sky coverage and 16,728 in number of matched objects. The astrometric matching and the treatment of SDSS masks have been refined for the updated catalog. We report on these improvements and present multiple bandpass light curves, global variability information, and matched SDSS photometry for 214,941 QUEST1 objects.
Folding DNA into Twisted and Curved Nanoscale Shapes
Dietz, Hendrik; Douglas, Shawn M.; Shih, William M.
2009-01-01
We demonstrate the ability to engineer complex shapes that twist and curve at the nanoscale from DNA. Through programmable self-assembly, strands of DNA are directed to form a custom-shaped bundle of tightly crosslinked double helices, arrayed in parallel to their helical axes. Targeted insertions and deletions of base pairs cause the DNA bundles to develop twist of either handedness or to curve. The degree of curvature could be quantitatively controlled, and a radius of curvature as tight as 6 nanometers was achieved. We also combined multiple curved elements to build several different types of intricate nanostructures, such as a wireframe beach ball or square-toothed gears. PMID:19661424
Implementation of Elliptic Curve Cryptography in Binary Field
NASA Astrophysics Data System (ADS)
Susantio, D. R.; Muchtadi-Alamsyah, I.
2016-04-01
Currently, there is a steadily increasing demand of information security, caused by a surge in information flow. There are many ways to create a secure information channel, one of which is to use cryptography. In this paper, we discuss the implementation of elliptic curves over the binary field for cryptography. We use the simplified version of the ECIES (Elliptic Curve Integrated Encryption Scheme). The ECIES encrypts a plaintext by masking the original message using specified points on the curve. The encryption process is done by separating the plaintext into blocks. Each block is then separately encrypted using the encryption scheme.
Method and models for R-curve instability calculations
NASA Technical Reports Server (NTRS)
Orange, Thomas W.
1990-01-01
This paper presents a simple method for performing elastic R-curve instability calculations. For a single material-structure combination, the calculations can be done on some pocket calculators. On microcomputers and larger, it permits the development of a comprehensive program having libraries of driving force equations for different configurations and R-curve model equations for different materials. The paper also presents several model equations for fitting to experimental R-curve data, both linear elastic and elastoplastic. The models are fit to data from the literature to demonstrate their viability.
Method and models for R-curve instability calculations
NASA Technical Reports Server (NTRS)
Orange, Thomas W.
1988-01-01
This paper presents a simple method for performing elastic R-curve instability calculations. For a single material-structure combination, the calculations can be done on some pocket calculators. On microcomputers and larger, it permits the development of a comprehensive program having libraries of driving force equations for different configurations and R-curve model equations for different materials. The paper also presents several model equations for fitting to experimental R-curve data, both linear elastic and elastoplastic. The models are fit to data from the literature to demonstrate their viability.
Interpretation of OAO-2 ultraviolet light curves of beta Doradus
NASA Technical Reports Server (NTRS)
Hutchinson, J. L.; Lillie, C. F.; Hill, S. J.
1975-01-01
Middle-ultraviolet light curves of beta Doradus, obtained by OAO-2, are presented along with other evidence indicating that the small additional bumps observed on the rising branches of these curves have their origin in shock-wave phenomena in the upper atmosphere of this classical Cepheid. A simple piston-driven spherical hydrodynamic model of the atmosphere is developed to explain the bumps, and the calculations are compared with observations. The model is found to be consistent with the shapes of the light curves as well as with measurements of the H-alpha radial velocities.
New Developments in Eclipsing Binary Light Curve Modeling
NASA Astrophysics Data System (ADS)
Milone, E. F.; Stagg, C. R.
1994-03-01
The light curve modeling of binary stars has continued to evolve since its founding by Henry Norris Russell (see Russell and Merrill 1952 and citations therein) nearly a century ago, accelerated in the 1950s by Kopal's introduction of Roche geometry into models and by the development of synthetic light curve computer code in the 1970's. Improved physics and the use of more kinds of observational input are providing another round of important advances that promise to enlarge our knowledge of both binary stars and ensembles containing them. Here we discuss the newer horizons of light curve modeling and the steps being taken toward them.
Curves showing column strength of steel and duralumin tubing
NASA Technical Reports Server (NTRS)
Ross, Orrin E
1929-01-01
Given here are a set of column strength curves that are intended to simplify the method of determining the size of struts in an airplane structure when the load in the member is known. The curves will also simplify the checking of the strength of a strut if the size and length are known. With these curves, no computations are necessary, as in the case of the old-fashioned method of strut design. The process is so simple that draftsmen or others who are not entirely familiar with mechanics can check the strength of a strut without much danger of error.
Compton, P.A.; Pecsi, M.
1984-01-01
The contents include: Geographical studies of the environment in Hungary; Environmental management in the Lake Balaton region; Environmental problems of the old and new coalfiels in the United Kingdom: managing the coal revival; urban climate and urban planning in Budapest; alternative energies and their environmental impact with special reference to the Severn Barrage. Management of the environment is the theme of this 1982 book on an exchange of views between Hungary and the United Kingdom. It provides the research work done by geographers in these two very contrasting countries.
Quantum Field Theory in Curved Spacetime
NASA Astrophysics Data System (ADS)
Reynolds, Sally C.; Gallagher, Andrew
2012-03-01
; 19. Assimilation and modern human origins in the African peripheries Fred H. Smith, Vance T. Hutchinson and Ivor Janković; 20. Patterns of Middle Pleistocene hominin evolution in Africa and the emergence of modern humans Emma Mbua and Günter Bräuer; 21. Integration of the genetic, anatomical, and archaeological data for the African origin of modern humans: problems and prospects Osbjorn M. Pearson; Part IV. In Search of Context: Hominin Environments, Behaviour and Lithic Cultures: 22. Animal palaeocommunity variability and habitat preference of robust australopiths in South Africa Darryl J. de Ruiter, Matt Sponheimer and Julia Lee-Thorp; 23. Impacts of environmental change and community ecology on the composition and diversity of the southern African monkey fauna from the Plio-Pleistocene to the present Sarah Elton; 24. African genesis revisited: reflections on Raymond Dart and the 'Predatory Transition from Ape(-Man) to Man' Travis R. Pickering; 25. Shared intention in early artefacts: an exploration of deep structure and implications for communication and language John A. J. Gowlett; 26. Sibudu Cave: recent archaeological work on the Middle Stone Age Lyn Wadley; 27. The oldest burials and their significance Avraham Ronen; Index.
Stewart, Leander; Evans, Neil; Bexon, Kimberley J; van der Meer, Dieudonne J; Williams, Graham A
2015-05-01
Although short tandem repeat profiling is extremely powerful in identifying individuals from crime scene stains, it is unable to differentiate between monozygotic (MZ) twins. Efforts to address this include mutation analysis through whole genome sequencing and through DNA methylation studies. Methylation of DNA is affected by environmental factors; thus, as MZ twins age, their DNA methylation patterns change. This can be characterized by bisulfite treatment followed by pyrosequencing. However, this can be time-consuming and expensive; thus, it is unlikely to be widely used by investigators. If the sequences are different, then in theory the melting temperature should be different. Thus, the aim of this study was to assess whether high-resolution melt curve analysis can be used to differentiate between MZ twins. Five sets of MZ twins provided buccal swabs that underwent extraction, quantification, bisulfite treatment, polymerase chain reaction amplification and high-resolution melting curve analysis targeting two markers, Alu-E2F3 and Alu-SP. Significant differences were observed between all MZ twins targeting Alu-E2F3 and in four of five MZ twins targeting Alu-SP (P<0.05). Thus, it has been demonstrated that bisulfite treatment followed by high-resolution melting curve analysis could be used to differentiate between MZ twins. PMID:25677265
A post-glacial relative sea-level curve from Fiordland, New Zealand
NASA Astrophysics Data System (ADS)
Dlabola, E. K.; Wilson, G. S.; Gorman, A. R.; Riesselman, C. R.; Moy, C. M.
2015-08-01
The modern fjords of southwest New Zealand were previously stranded lakes isolated from the Tasman Sea by bedrock and moraine sills following the retreat of glaciers at the Last Glacial Maximum. The isolated lake basins were subsequently inundated with sea water when sea-level rise overtopped the sills. A record of the lacustrine-to-marine environmental transition is preserved in the fjord basin sediments and is identified in two New Zealand fjords with high-resolution seismic data and paleoenvironmental analysis of sediment cores. Seismic data are used to constrain the maximum sill depth and microfossil assemblages are used to track the lacustrine-to-marine transition. Chronology is based on fourteen radiocarbon ages. A relative sea-level curve for Fiordland, New Zealand is constructed based on sill depths and age constraints on the marine incursion. The sea-level curve allows insights into estimated uplift rates for Fiordland during the Holocene. From a lowstand of at least 107 mbsl 14,750 yr ago, these data reveal a stepwise transgression. Meltwater Pulse 1b is identified between 12,400 and 11,400 yr ago, with a second acceleration in sea-level rise observed 9700 yr ago. This record contributes a new sea-level curve for a mid-latitude (45°S) Southern Hemisphere location as well as new evidence for Meltwater Pulse 1b.
NASA Astrophysics Data System (ADS)
Knuth, Eldon L.; Miller, David R.; Even, Uzi
2014-12-01
Data extracted from time-of-flight (TOF) measurements made on steady-state He free jets at Göttingen already in 1986 and for pulsed Ne free jets investigated recently at Tel Aviv have been added to an earlier plot of terminal condensed-phase mass fraction x2∞ as a function of the dimensionless scaling parameter Γ. Γ characterizes the source (fluid species, temperature, pressure and throat diameter); values of x2∞ are extracted from TOF measurements using conservation of energy in the free-jet expansion. For nozzles consisting of an orifice in a thin plate; the extracted data yield 22 data points which are correlated satisfactorily by a single curve. The Ne free jets were expanded from a conical nozzle with a 20° half angle; the three extracted data points stand together but apart from the aforementioned curve, indicating that the presence of the conical wall influences significantly the expansion and hence the condensation. The 22 data points for the expansions via an orifice consist of 15 measurements with expansions from the gas-phase side of the binodal curve which crossed the binodal curve downstream from the sonic point and 7 measurements with expansions of the gas-phase product of the flashing which occurred after an expansion from the liquid-phase side of the binodal curve crossed the binodal curve upstream from the sonic point. The association of these 22 points with a single curve supports the alternating-phase model for flows with flashing upstream from the sonic point proposed earlier. In order to assess the role of the spinodal curve in such expansions, the spinodal curves for He and Ne were computed using general multi-parameter Helmholtz-free-energy equation-of-state formulations. Then, for the several sets of source-chamber conditions used in the free-jet measurements, thermodynamic states at key locations in the free-jet expansions (binodal curve, sonic point and spinodal curve) were evaluated, with the expansion presumed to be metastable
Knuth, Eldon L.; Miller, David R.; Even, Uzi
2014-12-09
Data extracted from time-of-flight (TOF) measurements made on steady-state He free jets at Göttingen already in 1986 and for pulsed Ne free jets investigated recently at Tel Aviv have been added to an earlier plot of terminal condensed-phase mass fraction x{sub 2∞} as a function of the dimensionless scaling parameter Γ. Γ characterizes the source (fluid species, temperature, pressure and throat diameter); values of x{sub 2∞} are extracted from TOF measurements using conservation of energy in the free-jet expansion. For nozzles consisting of an orifice in a thin plate; the extracted data yield 22 data points which are correlated satisfactorily by a single curve. The Ne free jets were expanded from a conical nozzle with a 20° half angle; the three extracted data points stand together but apart from the aforementioned curve, indicating that the presence of the conical wall influences significantly the expansion and hence the condensation. The 22 data points for the expansions via an orifice consist of 15 measurements with expansions from the gas-phase side of the binodal curve which crossed the binodal curve downstream from the sonic point and 7 measurements with expansions of the gas-phase product of the flashing which occurred after an expansion from the liquid-phase side of the binodal curve crossed the binodal curve upstream from the sonic point. The association of these 22 points with a single curve supports the alternating-phase model for flows with flashing upstream from the sonic point proposed earlier. In order to assess the role of the spinodal curve in such expansions, the spinodal curves for He and Ne were computed using general multi-parameter Helmholtz-free-energy equation-of-state formulations. Then, for the several sets of source-chamber conditions used in the free-jet measurements, thermodynamic states at key locations in the free-jet expansions (binodal curve, sonic point and spinodal curve) were evaluated, with the expansion presumed to be
Cristy, G.A.; Jernigan, H.C.
1981-02-01
The record of the proceedings of the workshop on environmental decontamination contains twenty-seven presentations. Emphasis is placed upon soil and surface decontamination, the decommissioning of nuclear facilities, and assessments of instrumentation and equipment used in decontamination. (DLS)
Environmental aquatic photobiology is most commonly known for its links to global climate change. Ozone depletion is, however, not the only factor that alters the effects of ultraviolet radiation on biological systems. Alterations in water clarity, by acidification, reduced disso...
The thermal, chemical, and biological quality of water in rivers, lakes, reservoirs, and near coastal areas is inseparable from a consideration of hydraulic engineering principles: therefore, the term environmental hydraulics. In this chapter we discuss the basic principles of w...
NASA Technical Reports Server (NTRS)
1975-01-01
The potential use of space systems to help determine the current state of air, water, and land environments was examined; the effects of man's activities on these parameters were also examined. Data are limited to pollutants introduced into the major environmental media, environmental changes manifested by such pollutants, and the effectiveness of abatement and control methods. Data also cover land quality as related to land use and public health.
Environmental stress cracking of polymers
NASA Technical Reports Server (NTRS)
Mahan, K. I.
1980-01-01
A two point bending method for use in studying the environmental stress cracking and crazing phenomena is described and demonstrated for a variety of polymer/solvent systems. Critical strain values obtained from these curves are reported for various polymer/solvent systems including a considerable number of systems for which critical strain values have not been previously reported. Polymers studied using this technique include polycarbonate (PC), ABS, high impact styrene (HIS), polyphenylene oxide (PPO), and polymethyl methacrylate (PMMA). Critical strain values obtained using this method compared favorably with available existing data. The major advantage of the technique is the ability to obtain time vs. strain curves over a short period of time. The data obtained suggests that over a short period of time the transition in most of the polymer solvent systems is more gradual than previously believed.
Closed time like curves enable perfect state distinguishability
Harrington, James William; Wilde, Mark M; Brun, Todd A
2008-01-01
The causal self-consistency condition for closed timelike curves can give rise to nonlinear interactions on chronology-respecting qubits. We demonstrate that particular unitary interactions between closed timelike curve qubits and chronology-respecting qubits allow perfect distinguishability of nonorthogonal states, and provide a constructive proof for an arbitrary number of nonorthogonal states. This has a number of highly significant consequences. For example, an adversary with access to closed timelike curves can break the B92, BB84, and SARG04 quantum key distribution protocols, or any prepare-and-measure quantum key distribution scheme. Our result also implies that a party with access to closed timelike curves can violate the Holevo bound by accessing more than log(N) bits of information from an N-dimensional quantum state. In principle, he can transmit an arbitrarily large amount of classical information with a quantum system of fixed size. We discuss the implications of this for quantum cloning.
The excitation of normal modes by a curved line source
NASA Astrophysics Data System (ADS)
Mochizuki, E.
1987-12-01
The polynomial moments, up to total degree two, of the stress glut are calculated for a curved line source. The significance of the moments, whose total degree is one, is emphasized and the implication for inversion is discussed.
Sensitivity curves for searches for gravitational-wave backgrounds
NASA Astrophysics Data System (ADS)
Thrane, Eric; Romano, Joseph D.
2013-12-01
We propose a graphical representation of detector sensitivity curves for stochastic gravitational-wave backgrounds that takes into account the increase in sensitivity that comes from integrating over frequency in addition to integrating over time. This method is valid for backgrounds that have a power-law spectrum in the analysis band. We call these graphs “power-law integrated curves.” For simplicity, we consider cross-correlation searches for unpolarized and isotropic stochastic backgrounds using two or more detectors. We apply our method to construct power-law integrated sensitivity curves for second-generation ground-based detectors such as Advanced LIGO, space-based detectors such as LISA and the Big Bang Observer, and timing residuals from a pulsar timing array. The code used to produce these plots is available at https://dcc.ligo.org/LIGO-P1300115/public for researchers interested in constructing similar sensitivity curves.
Curved-channel microchannel array plates. [photoelectric detectors
NASA Technical Reports Server (NTRS)
Timothy, J. G.
1981-01-01
The microchannel array plate (MCP) is a photoelectric detector with an imaging capability comparable to that of a photographic plate. Recently MCPs in which the channels are curved to inhibit ion feedback have become available. These devices represent a major advance in MCP technology, since a single curved-channel MCP can be operated stably at high gain in the pulse-counting mode without any of the problems of stability of response or short lifetime reported for 'chevron' MCP detectors. Attention is given to the mode of operation of channel electron multipliers (CEM) and MCP, curved-channel MCP, test procedures, and performance characteristics. The accumulated test data show that the fundamental operating characteristics of the curved-channel MCP are directly related to those for the CEM.
43. FIRST FLOOR, REAR HALL: REAR HALLWAY BEHIND CURVED STAIRS ...
43. FIRST FLOOR, REAR HALL: REAR HALLWAY BEHIND CURVED STAIRS LOOKING NORTH TO 19TH CENTURY ADDITION. Arch defines north wall of original house. - George A. Trenholm Mansion, 172 Rutledge Avenue, Charleston, Charleston County, SC
View of the highway, at the Frozen Lake switchback curve, ...
View of the highway, at the Frozen Lake switchback curve, looking northwest. The proposed realignment would be just to the southeast (right) of the existing alignment - Beartooth Highway, Red Lodge, Montana to Cooke City, Montana, Cody, Park County, WY