Estimation of regional intensity-duration-frequency curves for extreme precipitation
DEFF Research Database (Denmark)
Madsen, Henrik; Mikkelsen, Peter Steen; Rosbjerg, Dan;
1998-01-01
Regional estimation of extreme precipitation from a high resolution rain gauge network in Denmark is considered. The applied extreme value model is based on the partial duration series (PDS) approach in which all events above a certain threshold level are modelled. For a preliminary assessment...
DEFF Research Database (Denmark)
Madsen, H.; Mikkelsen, Peter Steen; Rosbjerg, Dan
2002-01-01
A general framework for regional analysis and modeling of extreme rainfall characteristics is presented. The model is based on the partial duration series (PDS) method that includes in the analysis all events above a threshold level. In the PDS model the average annual number of exceedances, the ...
Liew, San Chuin; Raghavan, Srivatsan V.; Liong, Shie-Yui
2014-12-01
The impact of a changing climate is already being felt on several hydrological systems both on a regional and sub-regional scale of the globe. Southeast Asia is one of the regions strongly affected by climate change. With climate change, one of the anticipated impacts is an increase in the intensity and frequency of extreme rainfall which further increase the region's flood catastrophes, human casualties and economic loss. Optimal mitigation measures can be undertaken only when stormwater systems are designed using rainfall Intensity-Duration-Frequency (IDF) curves derived from a long and good quality rainfall data. Developing IDF curves for the future climate can be even more challenging especially for ungauged sites. The current practice to derive current climate's IDF curves for ungauged sites is, for example, to `borrow' or `interpolate' data from regions of climatologically similar characteristics. Recent measures to derive IDF curves for present climate was performed by extracting rainfall data from a high spatial resolution Regional Climate Model driven by ERA-40 reanalysis dataset. This approach has been demonstrated on an ungauged site (Java, Indonesia) and the results were quite promising. In this paper, the authors extend the application of the approach to other ungauged sites particularly in Peninsular Malaysia. The results of the study undoubtedly have significance contribution in terms of local and regional hydrology (Malaysia and Southeast Asian countries). The anticipated impacts of climate change especially increase in rainfall intensity and its frequency appreciates the derivation of future IDF curves in this study. It also provides policy makers better information on the adequacy of storm drainage design, for the current climate at the ungauged sites, and the adequacy of the existing storm drainage to cope with the impacts of climate change.
Ghosh, D. K.; Wang, D.; Obeysekera, J.; Hagen, S. C.
2013-12-01
The type, amount, intensity and frequency of rainfall are being directly influenced and altered due to potential climate changes. Consideration should be given to a revision of the rainfall intensity-duration-frequency (IDF) curve, developed based on the historical rainfall data, for storm water drainage design and flood control facilities. Proper adaptation by quantifying the potential effects of climate changes is one of the major ways to reduce vulnerability. As a result, updating IDF curves based on the future climate condition is very important for managing the hydraulic structures. In this study, the climate change impact to rainfall IDF curves over the Florida panhandle and peninsula are assessed using the COAPS Regional Downscaling data from the Florida Climate Institute. The COAPS Land-Atmosphere Regional Ensemble Climate Change Experiment for the Southeast United States at 10-km resolution consists of three regional climate models (RCM) by downscaling the general circulation models: the Community Climate System Model (CCSM), the Hadley Centre Coupled Model version 3 (HadCM3), and the Geophysical Fluid Dynamics Laboratory GCM (GFDL). The RCMs have been performed for the historical simulations (1969-1999) and the future projections (2038-2070) under the AR4 A2 emissions scenario. In this study, more than 30-years of hourly precipitation data are gathered from 57 weather stations in Florida. The performance of the RCMs is evaluated by comparing historical simulations with observations. The parameters of generalized extreme value (GEV) distributions including location, scale, and shape parameters are mapped for the period of 1969-1999 and 2038-2070. The spatial distribution map of rainfall intensity under various durations and return periods will be presented. The response on the Florida panhandle will be compared and contrasted with that of the larger peninsula. These maps will provide insight that can lead to a useful engineering tool for designing the
Cheng, Linyin; AghaKouchak, Amir
2014-11-18
Extreme climatic events are growing more severe and frequent, calling into question how prepared our infrastructure is to deal with these changes. Current infrastructure design is primarily based on precipitation Intensity-Duration-Frequency (IDF) curves with the so-called stationary assumption, meaning extremes will not vary significantly over time. However, climate change is expected to alter climatic extremes, a concept termed nonstationarity. Here we show that given nonstationarity, current IDF curves can substantially underestimate precipitation extremes and thus, they may not be suitable for infrastructure design in a changing climate. We show that a stationary climate assumption may lead to underestimation of extreme precipitation by as much as 60%, which increases the flood risk and failure risk in infrastructure systems. We then present a generalized framework for estimating nonstationary IDF curves and their uncertainties using Bayesian inference. The methodology can potentially be integrated in future design concepts.
A regional GEV scale-invariant framework for Intensity-Duration-Frequency analysis
Blanchet, J.; Ceresetti, D.; Molinié, G.; Creutin, J.-D.
2016-09-01
We propose in this paper a regional formulation of Intensity-Duration-Frequency curves of point-rainfall maxima in a scale-invariant Generalized Extreme Value (GEV) framework. The two assumptions we make is that extreme daily rainfall is GEV-distributed - which is justified by Extreme Value Theory (EVT) - and that extremes of aggregated daily rainfall follow simple-scaling relationships. Following these assumptions, we develop in a unified way a GEV simple-scaling model for extremes of aggregated daily rainfall over the range of durations where scaling applies. Then we propose a way of correcting this model for measurement frequency, giving a new GEV-scaling model for extremes of aggregated hourly rainfall. This model deviates from the simple-scaling assumption. This framework is applied to the Mediterranean region of Cévennes-Vivarais, France. A network of about 300 daily raingage stations covering the last 50 years and accumulated to span the range 1 day-1 week is used to fit the scale invariant GEV-model locally. By means of spatial interpolation of the model parameters, and correction for measurement frequency, we are able to build a regional model with good performances down to 1 h duration, even though only one hourly station is used to build the model. Finally we produce mean and return level maps within the region in the range 1 h-1 week and comment on the potential rain storms leading to these maps.
De Paola, Francesco; Giugni, Maurizio; Topa, Maria Elena; Coly, Adrien; Yeshitela, Kumelachew; Kombe, Wilbard; Tonye, Emmanuel; Touré, Hamidou
2013-04-01
The intensity-duration-frequency curves are used in hydrology to express in a synthetic way, the link between the maximum rainfall height h and a generic duration d of a rainfall event, fixed a given return period T. Generally, IDF curves can be characterized by a bi-parameter power law: h(d,T) = a(T)dn where a(T), and n are the parameters that have to be estimated through a probabilistic approach. An intensity-duration-frequency analysis starts by gathering time series record of different durations and extracting annual extremes for each duration. The annual extreme data are then fitted by a probability distribution. The present study, carried out within the FP7-ENV-2010 CLUVA project (CLimate change and Urban Vulnerability in Africa), regards the evaluation of the IDF curves for five case studies: Addis Ababa (Ethiopia), Dar Es Salaam (Tanzania), Douala (Cameroon), Ouagadouogou (Burkina Faso) and Saint Louis (Senegal). The probability distribution chosen to fit the annual extreme data is the classic Gumbel distribution. However, for the case studies, only the maximum annual daily rainfall heights are available. Therefore, to define the IDF curves and the extreme values in a smaller time window (10', 30', 1h, 3h, 6h, 12h), it is required to develop disaggregation techniques of the collected data, in order to generate a synthetic sequence of rainfall, with statistical properties equal to the recorded data. The daily rainfalls were disaggregated using two models: short-time intensity disaggregation model (10', 30', 1h); cascade-based disaggregation model (3h, 6h, 12h). On the basis of disaggegation models and Gumbel distribution , the parameters of the IDF curves for the five test cities were evaluated. In order to estimate the contingent influence of climate change on the IDF curves, the illustrated procedure has been applied to the climate (rainfall) simulations over the time period 2010-2050 provided by the CMCC (Centro Euro-Mediterraneo sui Cambiamenti Climatici
Intensity - Duration - Frequency Curves for U.S. Cities in a Warming Climate
Ragno, Elisa; AghaKouchak, Amir; Love, Charlotte; Vahedifard, Farshid; Cheng, Linyin; Lima, Carlos
2017-04-01
Current infrastructure design procedures rely on the use of Intensity - Duration - Frequency (IDF) curves retrieved under the assumption of temporal stationarity, meaning that occurrences of extreme events are expected to be time invariant. However, numerous studies have observed more severe extreme events over time. Hence, the stationarity assumption for extreme analysis may not be appropriate in a warming climate. This issue raises concerns regarding the safety and resilience of infrastructures and natural slopes. Here we employ daily precipitation data from historical and projected (RCP 8.5) CMIP5 runs to investigate IDF curves of 14 urban areas across the United States. We first statistically assess changes in precipitation extremes using an energy-based test for equal distributions. Then, through a Bayesian inference approach for stationary and non-stationary extreme value analysis, we provide updated IDF curves based on future climatic model projections. We show that, based on CMIP5 simulations, U.S cities may experience extreme precipitation events up to 20% more intense and twice as frequently, relative to historical records, despite the expectation of unchanged annual mean precipitation.
Kim, Byung Sik; Jeung, Se Jin; Lee, Dong Seop; Han, Woo Suk
2015-04-01
As the abnormal rainfall condition has been more and more frequently happen and serious by climate change and variabilities, the question whether the design of drainage system could be prepared with abnormal rainfall condition or not has been on the rise. Usually, the drainage system has been designed by rainfall I-D-F (Intensity-Duration-Frequency) curve with assumption that I-D-F curve is stationary. The design approach of the drainage system has limitation not to consider the extreme rainfall condition of which I-D-F curve is non-stationary by climate change and variabilities. Therefore, the assumption that the I-D-F curve is stationary to design drainage system maybe not available in the climate change period, because climate change has changed the characteristics of extremes rainfall event to be non-stationary. In this paper, design rainfall by rainfall duration and non-stationary I-D-F curve are derived by the conditional GEV distribution considering non-stationary of rainfall characteristics. Furthermore, the effect of designed peak flow with increase of rainfall intensity was analyzed by distributed rainfall-runoff model, S-RAT(Spatial Runoff Assessment Tool). Although there are some difference by rainfall duration, the traditional I-D-F curves underestimates the extreme rainfall events for high-frequency rainfall condition. As a result, this paper suggest that traditional I-D-F curves could not be suitable for the design of drainage system under climate change condition. Keywords : Drainage system, Climate Change, non-stationary, I-D-F curves This research was supported by a grant 'Development of multi-function debris flow control technique considering extreme rainfall event' [NEMA-Natural-2014-74] from the Natural Hazard Mitigation Research Group, National Emergency Management Agency of KOREA
De Paola, Francesco; Giugni, Maurizio; Topa, Maria Elena; Bucchignani, Edoardo
2014-01-01
Changes in the hydrologic cycle due to increase in greenhouse gases cause variations in intensity, duration, and frequency of precipitation events. Quantifying the potential effects of climate change and adapting to them is one way to reduce urban vulnerability. Since rainfall characteristics are often used to design water structures, reviewing and updating rainfall characteristics (i.e., Intensity-Duration-Frequency (IDF) curves) for future climate scenarios is necessary (Reg Environ Change 13(1 Supplement):25-33, 2013). The present study regards the evaluation of the IDF curves for three case studies: Addis Ababa (Ethiopia), Dar Es Salaam (Tanzania) and Douala (Cameroon). Starting from daily rainfall observed data, to define the IDF curves and the extreme values in a smaller time window (10', 30', 1 h, 3 h, 6 h, 12 h), disaggregation techniques of the collected data have been used, in order to generate a synthetic sequence of rainfall, with statistical properties similar to the recorded data. Then, the rainfall pattern of the three test cities was analyzed and IDF curves were evaluated. In order to estimate the contingent influence of climate change on the IDF curves, the described procedure was applied to the climate (rainfall) simulations over the time period 2010-2050, provided by CMCC (Centro Euro-Mediterraneo sui Cambiamenti Climatici). The evaluation of the IDF curves allowed to frame the rainfall evolution of the three case studies, considering initially only historical data, then taking into account the climate projections, in order to verify the changes in rainfall patterns. The same set of data and projections was also used for evaluating the Probable Maximum Precipitation (PMP).
Precipitation intensity-duration-frequency curves and their uncertainties for Ghaap plateau
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C.M. Tfwala
2017-01-01
Full Text Available Engineering infrastructures such as stormwater drains and bridges are commonly designed using the concept of Intensity-Duration-Frequency (IDF curves, which assume that the occurrence of precipitation patterns and distributions are spatially similar within the drainage area and remain unchanged throughout the lifespan of the infrastructures (stationary. Based on the premise that climate change will alter the spatial and temporal variability of precipitation patterns, inaccuracy in the estimation of IDF curves may occur. As such, prior to developing IDF curves, it is crucial to analyse trends of annual precipitation maxima. The objective of this study was to estimate the precipitation intensities and their uncertainties (lower and upper limits for durations of 0.125, 0.25, 0.5, 1, 2, 4, and 6 h and return periods of 2, 10, 25, 50 and 100 years in the Ghaap plateau, Northern Cape Province, South Africa using the Generalized Extreme Value (GEV distribution. The annual precipitation maxima were extracted from long-term (1918–2014 precipitation data for four meteorological stations (Postmasburg, Douglas, Kuruman and Groblershoop sourced from the South African Weather Services (SAWS. On average, the estimated extreme precipitation intensities for the plateau ranged from 4.2 mm/h for 6 h storm duration to 55.8 mm/h for 0.125 h at 2 years return period. At 100 year return period, the intensity ranged from 13.3 mm/h for 6 h duration to 175.5 mm/h for the duration of 0.125 h. The lower limit of uncertainty ranged from 11.7% at 2 years return period to 26% at 100 year return period, and from 12.8% to 58.4% for the upper limit for the respective return periods. This methodology can be integrated into policy formulation for the design of stormwater and flood management infrastructures in the Ghaap plateau, where mining is the main economic activity.
2016-03-01
second edition, texts in statistical science. United Kingdom: Chapman & Hall /CRC. Gelman, A., and D. B. Rubin. 1992. Inference from iterative...Soltyk, S., M. Leonard , A. Phatak, and E. Lehmann. 2014. Statistical modelling of rainfall intensity-frequency- duration curves using regional
Ghazavi, Reza; Moafi Rabori, Ali; Ahadnejad Reveshty, Mohsen
2016-01-01
Estimate design storm based on rainfall intensity–duration–frequency (IDF) curves is an important parameter for hydrologic planning of urban areas. The main aim of this study was to estimate rainfall intensities of Zanjan city watershed based on overall relationship of rainfall IDF curves and appropriate model of hourly rainfall estimation (Sherman method, Ghahreman and Abkhezr method). Hydrologic and hydraulic impacts of rainfall IDF curves change in flood properties was evaluated via Stormw...
Morin, Efrat; Marra, Francesco; Peleg, Nadav; Mei, Yiwen; Anagnostou, Emmanouil N.
2017-04-01
Rainfall frequency analysis is used to quantify the probability of occurrence of extreme rainfall and is traditionally based on rain gauge records. The limited spatial coverage of rain gauges is insufficient to sample the spatiotemporal variability of extreme rainfall and to provide the areal information required by management and design applications. Conversely, remote sensing instruments, even if quantitative uncertain, offer coverage and spatiotemporal detail that allow overcoming these issues. In recent years, remote sensing datasets began to be used for frequency analyses, taking advantage of increased record lengths and quantitative adjustments of the data. However, the studies so far made use of concepts and techniques developed for rain gauge (i.e. point or multiple-point) data and have been validated by comparison with gauge-derived analyses. These procedures add further sources of uncertainty and prevent from isolating between data and methodological uncertainties and from fully exploiting the available information. In this study, we step out of the gauge-centered concept presenting a direct comparison between at-site Intensity-Duration-Frequency (IDF) curves derived from different remote sensing datasets on corresponding spatial scales, temporal resolutions and records. We analyzed 16 years of homogeneously corrected and gauge-adjusted C-Band weather radar estimates, high-resolution CMORPH and gauge-adjusted high-resolution CMORPH over the Eastern Mediterranean. Results of this study include: (a) good spatial correlation between radar and satellite IDFs ( 0.7 for 2-5 years return period); (b) consistent correlation and dispersion in the raw and gauge adjusted CMORPH; (c) bias is almost uniform with return period for 12-24 h durations; (d) radar identifies thicker tail distributions than CMORPH and the tail of the distributions depends on the spatial and temporal scales. These results demonstrate the potential of remote sensing datasets for rainfall
Demissie, Y. K.; Mortuza, M. R.; Li, H. Y.
2015-12-01
The observed and anticipated increasing trends in extreme storm magnitude and frequency, as well as the associated flooding risk in the Pacific Northwest highlighted the need for revising and updating the local intensity-duration-frequency (IDF) curves, which are commonly used for designing critical water infrastructure. In Washington State, much of the drainage system installed in the last several decades uses IDF curves that are outdated by as much as half a century, making the system inadequate and vulnerable for flooding as seen more frequently in recent years. In this study, we have developed new and forward looking rainfall and runoff IDF curves for each county in Washington State using recently observed and projected precipitation data. Regional frequency analysis coupled with Bayesian uncertainty quantification and model averaging methods were used to developed and update the rainfall IDF curves, which were then used in watershed and snow models to develop the runoff IDF curves that explicitly account for effects of snow and drainage characteristic into the IDF curves and related designs. The resulted rainfall and runoff IDF curves provide more reliable, forward looking, and spatially resolved characteristics of storm events that can assist local decision makers and engineers to thoroughly review and/or update the current design standards for urban and rural storm water management infrastructure in order to reduce the potential ramifications of increasing severe storms and resulting floods on existing and planned storm drainage and flood management systems in the state.
Bairwa, Arvind Kumar; Khosa, Rakesh; Maheswaran, R.
2016-11-01
In this study, presence of multi-scale behaviour in rainfall IDF relationship has been established using Linear Probability Weighted Moments (LPWMs) for some selected stations in India. Simple, non-central moments (SMs) have seen widespread use in similar scaling studies but these latter statistical attributes are known to mask the 'true' scaling pattern and, consequently, leading to inappropriate inferences. There is a general agreement amongst researchers that conventional higher order moments do indeed amplify the extreme observations and drastically affect scaling exponents. Additional advantage of LPWMs over SMs is that they exist even when the standard moments do not exist. As an alternative, this study presents a comparison with results based on use of the robust LPWMs which have revealed, in sharp contrast with the conventional moments, a definitive multi-scaling behaviour in all four rainfall observation stations that were selected from different climatic zones. The multi-scale IDF curves derived using LPWMs show a good agreement with observations and it is accordingly concluded that LPWMs provide a more reliable tool for investigating scaling in sequences of observed rainfall corresponding to various durations.
Shahabul Alam, Md.; Nazemi, Alireza; Elshorbagy, Amin
2014-05-01
Intensity-Duration-Frequency (IDF) curves are among standard design criteria for various engineering applications, such as storm water management systems. Warming climate, however, changes the extreme rainfall quantiles represented by the IDF curves. This study attempts to construct the future IDF curves under possible climate change scenarios. For this purpose, a stochastic rainfall generator is used to spatially downscale the daily projections of Global Climate Models (GCMs) from coarse grid resolution to the point scale. The stochastically downscaled daily rainfall realizations can be further disaggregated to hourly and sub-hourly rainfall series using a deterministic disaggregation scheme developed based on the K-Nearest Neighbor (K-NN) method. We applied this framework for constructing the future IDF curves in the city of Saskatoon, Canada. As a model development step, the sensitivity of the K-NN disaggregation model to the number of nearest neighbors (i.e. window size) is evaluated during the baseline periods. The optimum window size is assigned based on the performance in reproducing the historical IDF curves. The optimum windows identified for 1-hour and 5-min temporal resolutions are then used to produce the future hourly and consequently, 5-min resolution rainfall based on the K-NN simulations. By using the simulated hourly and sub-hourly rainfall series and the Generalized Extreme Value (GEV) distribution future changes in IDF curves and associated uncertainties are quantified using a large ensemble of projections obtained for the CGCM3.1 and HadCM3 based on A1B, A2 and B1 emission scenarios in case of CMIP3 and RCP2.6, RCP4.5, and RCP8.5 in case of CMIP5 datasets. The constructed IDF curves for the city of Saskatoon are then compared with corresponding historical relationships at various durations and/or return periods and are discussed based on different models, emission scenarios and/or simulation release (i.e. CMIP3 vs. CMIP5).
Ghiaei, Farhad; Kankal, Murat; Anilan, Tugce; Yuksek, Omer
2016-10-01
The analysis of rainfall frequency is an important step in hydrology and water resources engineering. However, a lack of measuring stations, short duration of statistical periods, and unreliable outliers are among the most important problems when designing hydrology projects. In this study, regional rainfall analysis based on L-moments was used to overcome these problems in the Eastern Black Sea Basin (EBSB) of Turkey. The L-moments technique was applied at all stages of the regional analysis, including determining homogeneous regions, in addition to fitting and estimating parameters from appropriate distribution functions in each homogeneous region. We studied annual maximum rainfall height values of various durations (5 min to 24 h) from seven rain gauge stations located in the EBSB in Turkey, which have gauging periods of 39 to 70 years. Homogeneity of the region was evaluated by using L-moments. The goodness-of-fit criterion for each distribution was defined as the ZDIST statistics, depending on various distributions, including generalized logistic (GLO), generalized extreme value (GEV), generalized normal (GNO), Pearson type 3 (PE3), and generalized Pareto (GPA). GLO and GEV determined the best distributions for short (5 to 30 min) and long (1 to 24 h) period data, respectively. Based on the distribution functions, the governing equations were extracted for calculation of intensities of 2, 5, 25, 50, 100, 250, and 500 years return periods (T). Subsequently, the T values for different rainfall intensities were estimated using data quantifying maximum amount of rainfall at different times. Using these T values, duration, altitude, latitude, and longitude values were used as independent variables in a regression model of the data. The determination coefficient (R 2) value indicated that the model yields suitable results for the regional relationship of intensity-duration-frequency (IDF), which is necessary for the design of hydraulic structures in small and
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Rita de C. F. Damé
2008-06-01
Full Text Available Nos projetos agrícolas de obras hidráulicas, onde não se dispõe de dados observados de vazão, é necessário explorar ao máximo as informações relativas às curvas Intensidade-Duração-Freqüência (IDF. Diante disso, é preciso obter maneira de desenvolver metodologias de estimativas de curvas IDF, em locais que possuam pouco ou nenhum dado pluviográfico. O objetivo do trabalho foi comparar as metodologias de desagregação de precipitações diárias para verificar o ganho de informação em termos de curvas IDF, comparadas àquela obtida a partir de dados observados (histórica. Os métodos utilizados foram: (a Método das Relações (CETESB, 1979; (b BELTRAME et al. (1991; (c ROBAINA & PEITER (1992; (d Modelo Bartlett-Lewis do Pulso Retangular Modificado (DAMÉ, 2001. Utilizou-se de série de dados de precipitação diária de Pelotas - RS, referente ao período de 1982-1998. Para estimar as curvas IDF, a partir dos registros históricos, foram estabelecidas as durações de 15; 30; 60; 360; 720 e 1.440 minutos, e os períodos de retorno de 2; 5 e 10 anos. Os valores de intensidades máximas foram comparados entre si, pelo teste "t" de Student, para os coeficientes linear e angular, e pelo Erro Relativo Médio Quadrático. O método que melhor representou as intensidades máximas de precipitação, nos períodos de retorno de 2 e 10 anos, foi o Método das Relações (CETESB, 1979.Agricultural projects which deal with hydraulic projects and do not possess observed data on outflow need to explore at the most, information about the Intensity-Duration-Frequency (IDF curves. Thus, it is necessary to create ways to develop methodologies that estimate IDF curves for locations that have little or no pluviometric data. The aim of this work was to compare disaggregation methodologies for daily precipitation, to verify the increase in quality information considering the IDF curves, as compared to those originated from observed data
A point rainfall model and rainfall intensity-duration-frequency analysis
Energy Technology Data Exchange (ETDEWEB)
Yoo, Chul-Sang; Jung, Kwang-Sik [Korea University, Jochiwon(Korea); Kim, Nam-Won [Korea Institute of Construction Technology, Koyang(Korea)
2001-12-31
This study proposes a theoretical methodology for deriving a rainfall intensity-duration-frequency(I-D-F) curve using a simple rectangular pulses Poisson process model. As the I-D-F curve derived by considering the model structure is dependent on the rainfall model parameters estimated using the observed first and second order statistics, it becomes less sensitive to the unusual rainfall events than that derived using the annual maxima rainfall series. This study has been applied to the rainfall data at Seoul and Incheon stations to check its applicability by comparing the two I-D-F curves from the model and the data. The results obtained are as followed. (1) As the duration becomes longer, the overlap probability increases significantly. However, its contribution to the rainfall intensity decreases a little. (2) When considering the overlap of each rainfall event, especially for large duration and return period, we could see obvious increases of rainfall intensity. This result is normal as the rainfall intensity is calculated by considering both the overlap probability and return period. Also, the overlap effect for Seoul station is found much higher than that for Incheon station, which is mainly due to the different overlap probabilities calculated using different rainfall model parameter sets. (3) As the rectangular pulses Poisson processes model used in this study cannot consider the clustering characteristics of rainfall, the derived I-D-F curves show less rainfall intensities than those from the annual maxima series. However, overall pattern of both I-D-F curves are found very similar, and the difference is believed to be overcome by use of a rainfall model with the clustering consideration. (author). 14 refs., 6 tabs., 2 figs.
Agilan, V.; Umamahesh, N. V.
2017-03-01
Present infrastructure design is primarily based on rainfall Intensity-Duration-Frequency (IDF) curves with so-called stationary assumption. However, in recent years, the extreme precipitation events are increasing due to global climate change and creating non-stationarity in the series. Based on recent theoretical developments in the Extreme Value Theory (EVT), recent studies proposed a methodology for developing non-stationary rainfall IDF curve by incorporating trend in the parameters of the Generalized Extreme Value (GEV) distribution using Time covariate. But, the covariate Time may not be the best covariate and it is important to analyze all possible covariates and find the best covariate to model non-stationarity. In this study, five physical processes, namely, urbanization, local temperature changes, global warming, El Niño-Southern Oscillation (ENSO) cycle and Indian Ocean Dipole (IOD) are used as covariates. Based on these five covariates and their possible combinations, sixty-two non-stationary GEV models are constructed. In addition, two non-stationary GEV models based on Time covariate and one stationary GEV model are also constructed. The best model for each duration rainfall series is chosen based on the corrected Akaike Information Criterion (AICc). From the findings of this study, it is observed that the local processes (i.e., Urbanization, local temperature changes) are the best covariate for short duration rainfall and global processes (i.e., Global warming, ENSO cycle and IOD) are the best covariate for the long duration rainfall of the Hyderabad city, India. Furthermore, the covariate Time is never qualified as the best covariate. In addition, the identified best covariates are further used to develop non-stationary rainfall IDF curves of the Hyderabad city. The proposed methodology can be applied to other situations to develop the non-stationary IDF curves based on the best covariate.
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Ana Letícia Pilz de Castro
2011-08-01
Full Text Available Para a elaboração de projetos na área de drenagem urbana, o conhecimento adequado das precipitações máximas, que são normalmente determinadas a partir de relações Intensidade-Duração-Frequência, é muito importante. O presente trabalho apresenta um estudo para a obtenção da equação IDF para o município de Cuiabá, capital do Estado de Mato Grosso. Os dados utilizados no trabalho foram registrados por estação climatológica localizada em Várzea Grande (MT, com série histórica de 25 anos.AbstractIn order to develop projects in the urban drainage area, it is very important to be aware of adequate maximum rainfall, which is usually determined from relations among Intensity-Duration-Frequency. This paper presents a study to obtain the IDF equation for the Cuiaba city located in Mato Grosso State. The data used in the study were recorded by climatological station, located in Varzea Grande (MT with historical series during 25 years.
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M. Mohseni Saravi
2009-03-01
Full Text Available Precipitation deficit and its daily, seasonal and annual oscillations are inherent characteristics of Iran's climate. Droughts are generally characterized by a prolonged and abnormal moisture deficiency. In drought studies it is important to characterize the start and end of a drought as well as its intensity, duration, frequency and magnitude. The objective of this study was to analyze drought characteristics and to develop drought maps in the Karoon river basin, Iran. The Standardized Precipitation Index (SPI was used in drought analysis based on the data for meteorological stations located inside or adjacent to the study area and three time scales including the 3-, 6- and 12-month SPI were evaluated. After determining the dry and wet periods, historical characteristics of droughts were identified and spatial distribution maps of droughts were plotted using GIS. Based on frequency distributions, drought durations and magnitudes were computed corresponding to 5, 10, 20, 50 and 100-year return periods. The Time scale-Duration-Frequency (TDF and Time scale-Magnitude-Frequency (TMF relationships were also developed, which constitute an essential tool for water resource design purposes. Drought spatial distribution maps show that extreme conditions dominate the southeastern regions of the basin. The efficiency of the SPI is determined by monitoring the drought of 1999.
Chebbi, A.; Bargaoui, Z. K.; da Conceição Cunha, M.
2013-10-01
Based on rainfall intensity-duration-frequency (IDF) curves, fitted in several locations of a given area, a robust optimization approach is proposed to identify the best locations to install new rain gauges. The advantage of robust optimization is that the resulting design solutions yield networks which behave acceptably under hydrological variability. Robust optimization can overcome the problem of selecting representative rainfall events when building the optimization process. This paper reports an original approach based on Montana IDF model parameters. The latter are assumed to be geostatistical variables, and their spatial interdependence is taken into account through the adoption of cross-variograms in the kriging process. The problem of optimally locating a fixed number of new monitoring stations based on an existing rain gauge network is addressed. The objective function is based on the mean spatial kriging variance and rainfall variogram structure using a variance-reduction method. Hydrological variability was taken into account by considering and implementing several return periods to define the robust objective function. Variance minimization is performed using a simulated annealing algorithm. In addition, knowledge of the time horizon is needed for the computation of the robust objective function. A short- and a long-term horizon were studied, and optimal networks are identified for each. The method developed is applied to north Tunisia (area = 21 000 km2). Data inputs for the variogram analysis were IDF curves provided by the hydrological bureau and available for 14 tipping bucket type rain gauges. The recording period was from 1962 to 2001, depending on the station. The study concerns an imaginary network augmentation based on the network configuration in 1973, which is a very significant year in Tunisia because there was an exceptional regional flood event in March 1973. This network consisted of 13 stations and did not meet World Meteorological
Casas-Castillo, M. Carmen; Rodríguez-Solà, Raúl; Navarro, Xavier; Russo, Beniamino; Lastra, Antonio; González, Paula; Redaño, Angel
2016-11-01
The fractal behavior of extreme rainfall intensities registered between 1940 and 2012 by the Retiro Observatory of Madrid (Spain) has been examined, and a simple scaling regime ranging from 25 min to 3 days of duration has been identified. Thus, an intensity-duration-frequency (IDF) master equation of the location has been constructed in terms of the simple scaling formulation. The scaling behavior of probable maximum precipitation (PMP) for durations between 5 min and 24 h has also been verified. For the statistical estimation of the PMP, an envelope curve of the frequency factor (k m ) based on a total of 10,194 station-years of annual maximum rainfall from 258 stations in Spain has been developed. This curve could be useful to estimate suitable values of PMP at any point of the Iberian Peninsula from basic statistical parameters (mean and standard deviation) of its rainfall series.
Delgado, Oihane; Campo-Bescós, Miguel A.; López, J. Javier
2017-04-01
Frequently, when we are trying to solve certain hydrological engineering problems, it is often necessary to know rain intensity values related to a specific probability or return period, T. Based on analyses of extreme rainfall events at different time scale aggregation, we can deduce the relationships among Intensity-Duration-Frequency (IDF), that are widely used in hydraulic infrastructure design. However, the lack of long time series of rainfall intensities for smaller time periods, minutes or hours, leads to use mathematical expressions to characterize and extend these curves. One way to deduce them is through the development of synthetic rainfall time series generated from stochastic models, which is evaluated in this work. From recorded accumulated rainfall time series every 10 min in the pluviograph of Igueldo (San Sebastian, Spain) for the time period between 1927-2005, their homogeneity has been checked and possible statistically significant increasing or decreasing trends have also been shown. Subsequently, two models have been calibrated: Bartlett-Lewis and Markov chains models, which are based on the successions of storms, composed for a series of rainfall events, separated by a short interval of time each. Finally, synthetic ten-minute rainfall time series are generated, which allow to estimate detailed IDF curves and compare them with the estimated IDF based on the recorded data.
Directory of Open Access Journals (Sweden)
Arthur T. DeGaetano
2017-01-01
One-hundred-year recurrence interval precipitation amounts exhibit a median increase of between 5 and 10% across the state in the 2010–2039 period regardless of greenhouse gas concentration. By the 2040–2069 period, the median increase is on the order of 10–20% for the high concentration case (RCP 8.5, but remains below 10% if concentrations are lower (RCP 4.5. At the end of the century, all downscaling method climate model combinations indicate increases, with a median change of between 20 and 30% in the case of high concentrations.
Directory of Open Access Journals (Sweden)
Glenio G. Santos
2009-12-01
in the central and northern regions and lower intensities in the southeastern and southwestern regions of the State. These results demonstrated the importance of intensity-duration-frequency relationship and its use for studies and hydraulic projects based on data from each place.
National Research Council Canada - National Science Library
Rita de C. F. Damé; Claudia F. A. Teixeira; Viviane S. S. Terra
2008-01-01
... às curvas Intensidade-Duração-Freqüência (IDF). Diante disso, é preciso obter maneira de desenvolver metodologias de estimativas de curvas IDF, em locais que possuam pouco ou nenhum dado pluviográfico...
L curve for spherical triangle region quadtrees
Institute of Scientific and Technical Information of China (English)
YUAN; Wen; CHENG; Chengqi; MA; Ainai; GUAN; Xiaojing
2004-01-01
The sequence of facets and nodes has a direct influence on the efficiency of access to spherical triangle region quadtree. Based on the labeling schema by Lee,spatial curves both for facets and nodes are proposed and the main algorithms for coordinate translation, node L sequence generation and visiting nodes are presented. In particular, constant time algorithms for generating node L sequence are advanced by using bit manipulation operations, which can be easily implemented with hardware. In L curve the distance between three nodes of a facet is mostly limited in a range of small value, thus making fast access possible. Though codes of sibling facets are continuous,the difference between codes of some cousins may occasionally be very large and makes the distance of a few facets also very large, thus greatly increasing the mean node distance and the total traversing distance. Therefore an m cluster of nodes is proposed as a basic storage unit for n cluster, which should store every shared node in each, and the distance between three nodes of a facet is limited to a controllable scope.
Gottschlich, Carsten
2012-04-01
Gabor filters (GFs) play an important role in many application areas for the enhancement of various types of images and the extraction of Gabor features. For the purpose of enhancing curved structures in noisy images, we introduce curved GFs that locally adapt their shape to the direction of flow. These curved GFs enable the choice of filter parameters that increase the smoothing power without creating artifacts in the enhanced image. In this paper, curved GFs are applied to the curved ridge and valley structures of low-quality fingerprint images. First, we combine two orientation-field estimation methods in order to obtain a more robust estimation for very noisy images. Next, curved regions are constructed by following the respective local orientation. Subsequently, these curved regions are used for estimating the local ridge frequency. Finally, curved GFs are defined based on curved regions, and they apply the previously estimated orientations and ridge frequencies for the enhancement of low-quality fingerprint images. Experimental results on the FVC2004 databases show improvements of this approach in comparison with state-of-the-art enhancement methods.
Drawable Region of the Generalized Log Aesthetic Curves
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R. U. Gobithaasan
2013-01-01
Full Text Available The main characteristic of visually pleasing curves used for product design is a monotonic curvature profile. Recently, a planar curve called Generalized Log Aesthetic Curve (GLAC has been extended from the Log Aesthetic Curve (LAC, and it has an additional shape parameter, ν. This curve preserves the monotonicity of curvature and is said to produce visually pleasing curves. This paper delves on the drawable region of the GLAC segment which indicates the probable solutions of shape parameters from given interpolating points and the direction of travel at those points. The first section reviews the formulation of GLAC and its related bounds. The section describes the algorithm for identifying the drawable region. It is followed by the section describing how small changes of ν widen the drawable boundaries. The final section discusses the superiority of GLAC compared to LAC for use in industrial product design.
Gottschlich, Carsten
2012-04-01
Gabor filters play an important role in many application areas for the enhancement of various types of images and the extraction of Gabor features. For the purpose of enhancing curved structures in noisy images, we introduce curved Gabor filters which locally adapt their shape to the direction of flow. These curved Gabor filters enable the choice of filter parameters which increase the smoothing power without creating artifacts in the enhanced image. In this paper, curved Gabor filters are applied to the curved ridge and valley structure of low-quality fingerprint images. First, we combine two orientation field estimation methods in order to obtain a more robust estimation for very noisy images. Next, curved regions are constructed by following the respective local orientation and they are used for estimating the local ridge frequency. Lastly, curved Gabor filters are defined based on curved regions and they are applied for the enhancement of low-quality fingerprint images. Experimental results on the FVC2004 databases show improvements of this approach in comparison to state-of-the-art enhancement methods.
Simulating psychophysical tuning curves in listeners with dead regions
DEFF Research Database (Denmark)
Warnaar, Bastiaan; Jepsen, Morten Løve; Dreschler, Wouter A.
2013-01-01
Objective: This study investigates the relation between diagnosis of dead regions based on the off-frequency psychophysical tuning curve (PTC) tip and the frequency and level of the probe tone. Design: A previously developed functional model of auditory processing was used to simulate the complete...... the outcome of dead region diagnosis using PTCs. Supplementary to PTC dead region diagnostic information, model results may provide additional information regarding the edge frequency of a dead region and OHC function....
LEARNING CURVE IN ENDOSCOPIC TRANSNASAL SELLAR REGION SURGERY
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Ananth G
2016-07-01
Full Text Available BACKGROUND The endoscopic endonasal approach for the sellar region lesions is a novel technique and an effective surgical option. The evidence thus far has been conflicting with reports in favour and against a learning curve. We attempt to determine the learning curve associated with this approach. METHODS Retrospective and prospective data of the patients who were surgically treated for sellar region lesions between the year 2013 and 2016 was collected, 32 patients were operated by the endoscopic endonasal approach at Vydehi Institute of Medical Sciences and Research Centre, Bangalore. Age, sex, presenting symptoms, length of hospital stay, surgical approach, type of dissection, duration of surgery, sellar floor repair, intraoperative and postoperative complications were noted. All the procedures were performed by a single neurosurgeon. RESULTS A total of 32 patients were operated amongst which 21 patients were non-functioning pituitary adenomas, 2 were growth hormone secreting functional adenomas, 1 was an invasive pituitary adenoma, 4 were craniopharyngiomas, 2 were meningiomas, 1 was Rathke’s cleft cyst and 1 was a clival chordoma. Headache was the mode of presentation in 12 patients, 12 patients had visual deficits, 6 patients presented with hormonal disturbances amongst which 4 patients presented with features of panhypopituitarism and 2 with acromegaly. Amongst the 4 patients with panhypopituitarism, 2 also had DI, two patients presented with CSF rhinorrhoea. There was a 100% improvement in the patients who presented with visual symptoms. Gross total resection was achieved in all 4 cases of craniopharyngiomas and 13 cases of pituitary adenomas. Postoperative CSF leak was seen in 4 patients who underwent re-exploration and sellar floor repair, 9 patients had postoperative Diabetes Insipidus (DI which was transient, the incidence of DI reduced towards the end of the study. There was a 25% decrease in the operating time towards the end of
Bounding Regions to Plane Steepest Descent Curves of Quasiconvex Families
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Marco Longinetti
2016-01-01
Full Text Available Two-dimensional steepest descent curves (SDC for a quasiconvex family are considered; the problem of their extensions (with constraints outside of a convex body K is studied. It is shown that possible extensions are constrained to lie inside of suitable bounding regions depending on K. These regions are bounded by arcs of involutes of ∂K and satisfy many inclusions properties. The involutes of the boundary of an arbitrary plane convex body are defined and written by their support function. Extensions SDC of minimal length are constructed. Self-contracting sets (with opposite orientation are considered: necessary and/or sufficient conditions for them to be subsets of SDC are proved.
Energy Technology Data Exchange (ETDEWEB)
Saelthun, Nils Roar [ed.; Tveito, Ole Einar; Boensnes, Truls Erik; Roald, Lars A.
1997-07-30
This report establishes new regional growth curves for Norway for annual daily maximum floods based on the general extreme value distribution. The parameters of the regional distributions were estimated by the probability weighted moment method. The regions were established by the hierarchical cluster analysis. The homogeneity of each region was examined by use of Wilt shires R-test. New regional formulae were established linking the mean annual flood to basin characteristics. The results have been compared to the previous set of regional growth curves and regional formulae predicting the mean annual flood. The relation between peak flood and daily values has been examined. A formula for predicting peak flood quantiles for a given daily flood quantile has been developed. 22 refs., 24 figs., 8 tabs.
Regional flow duration curves: Geostatistical techniques versus multivariate regression
Pugliese, Alessio; Farmer, William H.; Castellarin, Attilio; Archfield, Stacey A.; Vogel, Richard M.
2016-10-01
A period-of-record flow duration curve (FDC) represents the relationship between the magnitude and frequency of daily streamflows. Prediction of FDCs is of great importance for locations characterized by sparse or missing streamflow observations. We present a detailed comparison of two methods which are capable of predicting an FDC at ungauged basins: (1) an adaptation of the geostatistical method, Top-kriging, employing a linear weighted average of dimensionless empirical FDCs, standardised with a reference streamflow value; and (2) regional multiple linear regression of streamflow quantiles, perhaps the most common method for the prediction of FDCs at ungauged sites. In particular, Top-kriging relies on a metric for expressing the similarity between catchments computed as the negative deviation of the FDC from a reference streamflow value, which we termed total negative deviation (TND). Comparisons of these two methods are made in 182 largely unregulated river catchments in the southeastern U.S. using a three-fold cross-validation algorithm. Our results reveal that the two methods perform similarly throughout flow-regimes, with average Nash-Sutcliffe Efficiencies 0.566 and 0.662, (0.883 and 0.829 on log-transformed quantiles) for the geostatistical and the linear regression models, respectively. The differences between the reproduction of FDC's occurred mostly for low flows with exceedance probability (i.e. duration) above 0.98.
Regional flow duration curves: Geostatistical techniques versus multivariate regression
Pugliese, Alessio; Farmer, William H.; Castellarin, Attilio; Archfield, Stacey A.; Vogel, Richard M.
2016-01-01
A period-of-record flow duration curve (FDC) represents the relationship between the magnitude and frequency of daily streamflows. Prediction of FDCs is of great importance for locations characterized by sparse or missing streamflow observations. We present a detailed comparison of two methods which are capable of predicting an FDC at ungauged basins: (1) an adaptation of the geostatistical method, Top-kriging, employing a linear weighted average of dimensionless empirical FDCs, standardised with a reference streamflow value; and (2) regional multiple linear regression of streamflow quantiles, perhaps the most common method for the prediction of FDCs at ungauged sites. In particular, Top-kriging relies on a metric for expressing the similarity between catchments computed as the negative deviation of the FDC from a reference streamflow value, which we termed total negative deviation (TND). Comparisons of these two methods are made in 182 largely unregulated river catchments in the southeastern U.S. using a three-fold cross-validation algorithm. Our results reveal that the two methods perform similarly throughout flow-regimes, with average Nash-Sutcliffe Efficiencies 0.566 and 0.662, (0.883 and 0.829 on log-transformed quantiles) for the geostatistical and the linear regression models, respectively. The differences between the reproduction of FDC's occurred mostly for low flows with exceedance probability (i.e. duration) above 0.98.
Energy Technology Data Exchange (ETDEWEB)
Ye, Sheng; Li, Hongyi; Huang, Maoyi; Ali, Melkamu; Leng, Guoyong; Leung, Lai-Yung R.; Wang, Shaowen; Sivapalan, Murugesu
2014-07-21
Subsurface stormflow is an important component of the rainfall–runoff response, especially in steep terrain. Its contribution to total runoff is, however, poorly represented in the current generation of land surface models. The lack of physical basis of these common parameterizations precludes a priori estimation of the stormflow (i.e. without calibration), which is a major drawback for prediction in ungauged basins, or for use in global land surface models. This paper is aimed at deriving regionalized parameterizations of the storage–discharge relationship relating to subsurface stormflow from a top–down empirical data analysis of streamflow recession curves extracted from 50 eastern United States catchments. Detailed regression analyses were performed between parameters of the empirical storage–discharge relationships and the controlling climate, soil and topographic characteristics. The regression analyses performed on empirical recession curves at catchment scale indicated that the coefficient of the power-law form storage–discharge relationship is closely related to the catchment hydrologic characteristics, which is consistent with the hydraulic theory derived mainly at the hillslope scale. As for the exponent, besides the role of field scale soil hydraulic properties as suggested by hydraulic theory, it is found to be more strongly affected by climate (aridity) at the catchment scale. At a fundamental level these results point to the need for more detailed exploration of the co-dependence of soil, vegetation and topography with climate.
Directory of Open Access Journals (Sweden)
Nori Paulo Griebeler
2007-09-01
Full Text Available
Este trabalho teve como objetivo a obtenção das relações intensidade-duração-frequência para algumas localidades do Estado de Goiás e Distrito Federal, empregando-se a metodologia da desagregação da chuva de um dia. Os resultados das intensidades de precipitação obtidos pelas equações geradas neste trabalho foram comparados com os obtidos pelas equações ajustadas com base em dados de pluviogramas. As relações geradas com o método de desagregação de chuvas de um dia apresentaram desvios relativos médios que variaram de -1,6% a 43,9%, para alguns municípios nessa região. Isso limita a sua utilização nas localidades para as quais não se ajustaram as equações de regressão.
PALAVRAS-CHAVE: Chuva intensa; drenagem; intensidade-duração-frequência.
This study had the objective of obtaining rain intensityduration- frequency information for some sites in the State of Goiás and Distrito Federal, using the one-day rain disaggregation method. The precipitation intensities obtained through the equations generated in this paper were compared to those obtained by adjusted equations based on pluviographic data. The intensityduration-frequency relationships generated through pluviometric data using the one-day rain disaggregation method presented relative mean deviations varying between -1.6% and 43.9%, for some municipalities in this region. This limits its use in sites where regression equations were not adjusted.
KEY-WORDS: Intense rainfall; drainage; intensity-durationfrequency.
Directory of Open Access Journals (Sweden)
Lichun Xiong
2017-05-01
Full Text Available The Beijing-Tianjin-Hebei Region Integration Plan is one of the most important national strategies in China promoting regional economic development. The environmental problems in this region, however, especially air pollution and contaminated groundwater, have enormous influence on the people’s health while also causing economic loss. Therefore, this study aims to analyze the pattern of its environmental and economic development. Panel data in the period 2004–2014 are used to establish an advanced model of the Environmental Kuznets Curve. The results indicate that the economic growth and environmental pollution of Beijing-Tianjin-Hebei region do not completely meet the Environment Kuznets Curve assumptions. The discharge volume of industrial wastewater and economic growth reflect a wave-type relation. The sulfur dioxide discharge volume and economic growth reflect a U-shaped relation; the generated volume of industrial solid wastes and economic growth reflect a reversed N-shaped relation, which is in accordance with the Environmental Kuznets Curve characteristics at the second inflection point. The variables added value of the secondary industry, population size and raw coal consumption volume have a significant positive influence on the discharge of various environmental pollutants in Beijing-Tianjin-Hebei region. The analysis provides policy recommendations for the government to develop regional economic and environmental protection policies.
Energy Technology Data Exchange (ETDEWEB)
Maione, U.; Romiti, R.; Tomirotti, M. [Milan Politecnico, Milan (Italy). Dipt. di Ingegneria Idraulica, Ambientale e del Rilevamento
2000-06-01
In the present paper a regional model for the estimation of storm depths for the Po river basin is proposed. The method is based on the introduction of a probabilistic model depending only on the standard deviation of the random variable; this model has been calibrated upon the largest values of the historical series of the annual maxima of rainfall depths in given duration available for the gauging stations belonging to the region under study. Adopting the usual monomial formula for the intensity-duration-frequency curves, the parameters of these curves have been expressed in terms of the standard deviation of the maximum annual 1-hour and 24-hour rainfall depths. The regional estimation of the intensity-duration-frequency curves has been accomplished by mapping the contour lines of the standard deviation of the maximum annual 1-hour and 1-day rainfall depths after calibration of a relation between the latter and the standard deviation of the maximum annual 24-hour rainfall depth. The performances of the method have been compared with those coming from other models recently proposed in literature. [Italian] Nella presente memoria viene proposto un metodo di stima regionale delle piogge intense per il bacino del Po. Esso si basa sull'introduzione di un modello probabilistico dipendente dal solo scarto quadratico medio della variabile; tale modello e' stato tarato sui valori massimi delle serie storiche delle altezze massime annuali di precipitazione in assegnata durata relative alle stazioni pluviografiche ricadenti nell'area di indagine. Adottando la consueta espressione monomia delle linee segnalatrici di possibilita' pluviometrica, i parametri di tali curve sono stati espressi in funzione dello scarto quadratico medio dell'altezza di precipitazione massima annuale di durata 1 e 24 ore. La stima regionale delle linee segnalatrici di possibilita' pluviometrica e' stata ottenuta mediante la costruzione di mappe delle isolinee
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Dar Abdul Qayoom
2016-01-01
Full Text Available Knowledge of rainfall extremes particularly their magnitude and frequency, as embodied in Intensity-Duration-Frequency (IDF relationships and IDF curves is fundamental to many engineering problems such as design of hydraulic structures, urban drainage system, water resources projects and many others. The objective of this study is to obtain IDF relationships and curves for the Kupwara region of Kashmir valley in Jammu and Kashmir, India. Three different frequency distributions namely the Gumbel distribution, the Pearson Type III distribution and the Log-Pearson Type III distribution were fitted to the rainfall data to obtain rainfall intensities for selected return periods (2, 5, 10, 25, 50 and 100 years and durations (0.16, 0.5, 1, 3, 6, 12 and 24 hours. Regional constants in IDF relations were found using the Sherman Morrison method and results were compared based on the Chi-square goodness-of-fit test. Results obtained using all distributions showed a similar trend. However, the Pearson Type III distribution emerges to be the best fit for the rainfall data of the region. Results revealed that higher rainfall intensities have shorter durations. Maximum rainfall intensity 81.13 mm/hr as per the best fit relation occurs with a return period of 100 years for 0.16 hours duration.
Obtaining DDF Curves of Extreme Rainfall Data Using Bivariate Copula and Frequency Analysis
DEFF Research Database (Denmark)
Sadri, Sara; Madsen, Henrik; Mikkelsen, Peter Steen
2009-01-01
The traditional rainfall intensity-duration-frequency (IDF) curve is a reliable approach for representing the variation of rainfall intensity with duration for a given return period. In reality rainfall variables intensity, depth and duration are dependent and therefore a bivariate analysis using...... copulas can give a more accurate IDF curve. We study IDF curves using a copula in a bivariate frequency analysis of extreme rainfall. To be able to choose the most suitable copula among candidate copulas (i.e., Gumbel, Clayton, and Frank) we demonstrated IDF curves based on variation of depth...... with duration for a given return period and name them DDF (depth-duration-frequency) curves. The copula approach does not assume the rainfall variables are independent or jointly normally distributed. Rainfall series are extracted in three ways: (1) by maximum mean intensity; (2) by depth and duration...
The environmental Kuznets curve hypothesis for water pollution: Do regions matter?
Energy Technology Data Exchange (ETDEWEB)
Lee, C.-C., E-mail: leecc@seed.net.t [Department of Finance, National Sun Yat-Sen University Kaohsiung, Taiwan (China); Chiu, Y.-B. [Department of Finance, National Sun Yat-Sen University Kaohsiung, Taiwan (China); Sun, C.-H. [Department of Economics, National Chung Cheng University, Taiwan (China)
2010-01-15
This study revisits the environmental Kuznets curve (EKC) hypothesis for water pollution by using a recent dynamic technique, which is the generalized method of moments (GMM) approach, for a board sample of 97 countries during the period 1980-2001. On a global scale, as we cannot obtain the EKC relationship between real income and biological oxygen demand (BOD) emissions, this paper further classifies these countries into four regional groups - Africa, Asia and Oceania, America, and Europe - to explore whether the different regions have different ECK relationships. The empirical results show evidence of the inverted U-shaped EKC relationships' existence in America and Europe, but not in Africa and Asia and Oceania. Thus, the regional difference of EKC for water pollution is supported. Furthermore, the estimated turning points are, approximately, US$13,956 and US$38,221 for America and Europe, respectively.
The environmental Kuznets curve hypothesis for water pollution. Do regions matter?
Energy Technology Data Exchange (ETDEWEB)
Lee, Chien-Chiang; Chiu, Yi-Bin [Department of Finance, National Sun Yat-Sen University Kaohsiung (China); Sun, Chia-Hung [Department of Economics, National Chung Cheng University (China)
2010-01-15
This study revisits the environmental Kuznets curve (EKC) hypothesis for water pollution by using a recent dynamic technique, which is the generalized method of moments (GMM) approach, for a board sample of 97 countries during the period 1980-2001. On a global scale, as we cannot obtain the EKC relationship between real income and biological oxygen demand (BOD) emissions, this paper further classifies these countries into four regional groups - Africa, Asia and Oceania, America, and Europe - to explore whether the different regions have different ECK relationships. The empirical results show evidence of the inverted U-shaped EKC relationships' existence in America and Europe, but not in Africa and Asia and Oceania. Thus, the regional difference of EKC for water pollution is supported. Furthermore, the estimated turning points are, approximately, US$13,956 and US$38,221 for America and Europe, respectively. (author)
Claus, Andrew P; Hides, Julie A; Moseley, G Lorimer; Hodges, Paul W
2009-03-15
Exploratory study of regional muscle activity in different postures. To detail the relationship between spinal curves and regional muscle activity. Sagittal balanced spinal posture (C7 above S1 in the sagittal plane) is a goal for spinal surgery and conservative ergonomics. Three combinations of thoracolumbar and lumbar spinal curves can be considered sagittal balanced postures: (i) flat-at both regions, (ii) long lordosis-lordotic at both regions, and (iii) short lordosis-thoracic kyphosis and lumbar lordosis. This study compares regional muscle activity between these 3 sagittal balanced postures in sitting, as well as a slump posture. Fine-wire electromyography (EMG) electrodes were inserted into the lumbar multifidus (deep and superficial), iliocostalis (lateral and medial), longissimus thoracis, and transversus abdominis in 14 healthy male volunteers. Fine-wire or surface EMG electrodes were also used to record activity of the obliquus internus, obliquus externus, and rectus abdominis muscles. Root mean square EMG amplitude in the flat, long lordosis, short lordosis, and slump sitting postures were normalized to maximal voluntary contraction, and also to the peak activity across the sitting postures. Muscle activity was compared between postures with a linear mixed model analysis. Of the extensor muscles, it was most notable that activity of the deep and superficial fibers of lumbar multifidus increased incrementally in the 3 sagittal balanced postures; flat, long lordosis, and short lordosis (P sagittal balanced postures, the flat posture showed the least muscle activity (similar to the slump posture at most muscles examined). Discrete combinations of muscle activity supported the 3 different sagittal balanced postures in sitting, providing new detail for surgeons, researchers, and therapists to distinguish between different sagittal balanced postures.
Biochar effects on wet and dry regions of the soil water retention curve of a sandy loam
DEFF Research Database (Denmark)
Arthur, Emmanuel; Moldrup, Per; Sun, Zhencai;
2014-01-01
Reported beneficial effects of biochar on soil physical properties and processes include decreased soil density, and increased soil water transport, water holding capacity and retention (mainly for the wet region). Research is limited on biochar effects on the full soil water retention curve (wet...... and dry regions) for a given soil and biochar amendment scenarios. This study evaluates how biochar applied to a sandy loam field at rates from 0 to 50 Mg ha−1 yr–1 in 2011, 2012, or both years (2011+2012) influences the full water retention curve. Inorganic fertilizer and pig slurry were added to all...... region-water retention curve increased with increasing biochar rates....
Preliminary Archaeointensity Reference Curve for the "Four Corners" Region of the American Southwest
Jones-Cervantes, S. A.; Tauxe, L.; Blinman, E.; Genevey, A.
2016-12-01
A preliminary high quality archeointensity reference curve was developed for the last 2000 years for the Four Corners region of the American Southwest. This region includes the states of New Mexico, Arizona, Colorado and Utah. The curve is derived from two data sources: new data collected during the course of this study and previously published data filtered for the highest quality. New paleointensity experiments were conducted using the IZZI protocol on three hundred and four specimens from fifty-seven baked pottery fragments collected from nine archaeological sites near Santa Fe, New Mexico. Anisotropy of remanence is a common problem in archaeological material so we conducted anisotropy experiments to correct for this behavior. In addition, we evaluated the effect of cooling rate in our specimens and adjusted intensity values accordingly. The corrected intensity estimates for successful samples were converted to Virtual Axial Dipole Moments (VADMs). Stylistic evidence, historical documentation, dendrochronology, and 14C analyses provide age constraints with up to decade resolution for the VADM results. Previously published archaeointensity values were retrieved from the GeoMAGIA database (Brown et al., 2015). The accuracy of the data and metadata retrieved from the database was verified and corrected, when necessary, from the original publications. These corrected data were filtered for the highest quality: a statistical "n" greater than or equal to three, a VADM standard deviation less than or equal to 5%, and an age sigma of less than or equal to 150 years. The resulting archaeointensity curve varies in magnitude from approximately 80 ZAm2 during the 7th century to a peak of roughly 145 ZAm2 during the 14th century. During this interval the field increased in magnitude at a rate of 9.3 ZAm2 per century. Since the 14th century the field has been decreasing in magnitude at generally the same rate.
Batir, Joseph F.; Blackwell, David D.; Richards, Maria C.
2016-06-01
The objective of this research is to contribute to the understanding of the thermal regime of Alaska and its relationship to geology, regional tectonics, and to suggest potential sites for future geothermal energy production. New heat flow data were collected and are combined with existing published and unpublished data, although large sections of Alaska still lack data. Fault traces were implemented into the heat flow contouring as an additional gridding constraint, to incorporate both heat flow measurements and geology. New heat flow data supported the use of geologic trends in the heat flow mapping procedure, and a heat flow map of Alaska was produced with this added constraint. The multi-input contouring strategy allows production of a map with a regional interpretation of heat flow, in addition to site-specific heat flow and thermal model interpretations in areas with sufficient data density. Utilizing the new heat flow map, temperature-at-depth curves were created for example areas. Temperature-at-depth curves are calculated to 10 km depth for the areas of Anchorage, Fairbanks, Juneau, the Alaska Peninsula, Bristol Bay, and the Copper River Basin. The temperatures-at-depth predicted near the population centers of Anchorage and Juneau are relatively low, limiting the geothermal resource potential. The Fairbanks area temperature estimates are near conventional power production temperatures (150 °C) between 3.5 and 4 km. All data areas, except at Juneau, have temperatures sufficient for low temperature geothermal applications (40 °C) by 2 km. A high heat flow region exists within the Aleutian Volcanic Arc, although new data show heat flow variations from 59 to 120 mW m-2, so individual geothermal resources within the arc will be irregularly located.
A numerical study of entrance region in a curved annulus with an inward and outward eccentricity
Directory of Open Access Journals (Sweden)
M.R.H. Nobari
2016-09-01
Full Text Available In this article, developing incompressible fluid flow in a curved annulus with inward and outward eccentricities is studied numerically. To do so, a second order finite difference method based on the projection algorithm is employed to solve the governing equations written in a general bipolar–toroidal coordinate system using a three-dimensional staggered uniform grid. The effects of the governing dimensionless parameters such as the Dean number, Reynolds number, curvature ratio, aspect ratio, and eccentricity on the flow field pattern and friction factor are studied in the entrance region. The numerical results obtained indicate that the outward eccentricity significantly deforms the secondary flows and axial velocity profiles. Furthermore, as the eccentricity increases, the friction factor decreases due to the reduction of secondary flow intensity.
Amino Terminal Region of Dengue Virus NS4A Cytosolic Domain Binds to Highly Curved Liposomes.
Hung, Yu-Fu; Schwarten, Melanie; Hoffmann, Silke; Willbold, Dieter; Sklan, Ella H; Koenig, BerndW
2015-07-21
Dengue virus (DENV) is an important human pathogen causing millions of disease cases and thousands of deaths worldwide. Non-structural protein 4A (NS4A) is a vital component of the viral replication complex (RC) and plays a major role in the formation of host cell membrane-derived structures that provide a scaffold for replication. The N-terminal cytoplasmic region of NS4A(1-48) is known to preferentially interact with highly curved membranes. Here, we provide experimental evidence for the stable binding of NS4A(1-48) to small liposomes using a liposome floatation assay and identify the lipid binding sequence by NMR spectroscopy. Mutations L6E;M10E were previously shown to inhibit DENV replication and to interfere with the binding of NS4A(1-48) to small liposomes. Our results provide new details on the interaction of the N-terminal region of NS4A with membranes and will prompt studies of the functional relevance of the curvature sensitive membrane anchor at the N-terminus of NS4A.
Spatially-smooth regionalization of flow duration curves in non-pristine basins
Ganora, Daniele; Laio, Francesco; Masoero, Alessandro; Claps, Pierluigi
2016-05-01
The flow duration curve (FDC) is a fundamental signature of the hydrological cycle to support water management strategies. Despite many studies on this topic, its estimation in ungauged basins is still a relevant issue as the FDC is controlled by different types of processes at different time-space scales, thus resulting quite sensitive to the specific case study. In this work, a regional spatially-smooth procedure to evaluate the annual FDC in ungauged basins is proposed, based on the estimation of the L-moments (mean, L-CV and L-skewness) through regression models valid for the whole case study area. In this approach, homogeneous regions are no longer required and the L-moments are allowed to continuously vary along the river network, thus providing a final FDC smoothly evolving for different locations on the river. Regressions are based on a set of topographic, climatic, land use and vegetation descriptors at the basin scale. Moreover, the model ensures that the mean annual runoff is preserved at the river confluences, i.e. the sum of annual flows of the upstream reaches is equal to the predicted annual downstream flow. The proposed model is adapted to incorporate different "sub-models" to account for local information within the regional framework, where man-induced alterations are known, as common in non-pristine catchments. In particular, we propose a module to consider the impact of existing/designed water withdrawals on the L-moments of the FDC. The procedure has been applied to a dataset of daily observation of about 120 gauged basins on the upper Po river basin in North-Western Italy.
Directory of Open Access Journals (Sweden)
João Carlos Medeiros
2014-06-01
Full Text Available Knowledge of the soil water retention curve (SWRC is essential for understanding and modeling hydraulic processes in the soil. However, direct determination of the SWRC is time consuming and costly. In addition, it requires a large number of samples, due to the high spatial and temporal variability of soil hydraulic properties. An alternative is the use of models, called pedotransfer functions (PTFs, which estimate the SWRC from easy-to-measure properties. The aim of this paper was to test the accuracy of 16 point or parametric PTFs reported in the literature on different soils from the south and southeast of the State of Pará, Brazil. The PTFs tested were proposed by Pidgeon (1972, Lal (1979, Aina & Periaswamy (1985, Arruda et al. (1987, Dijkerman (1988, Vereecken et al. (1989, Batjes (1996, van den Berg et al. (1997, Tomasella et al. (2000, Hodnett & Tomasella (2002, Oliveira et al. (2002, and Barros (2010. We used a database that includes soil texture (sand, silt, and clay, bulk density, soil organic carbon, soil pH, cation exchange capacity, and the SWRC. Most of the PTFs tested did not show good performance in estimating the SWRC. The parametric PTFs, however, performed better than the point PTFs in assessing the SWRC in the tested region. Among the parametric PTFs, those proposed by Tomasella et al. (2000 achieved the best accuracy in estimating the empirical parameters of the van Genuchten (1980 model, especially when tested in the top soil layer.
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A.D.V. Garnero
2013-08-01
Full Text Available This work aims to determine the most suitable nonlinear model to describe the growth of female collared peccaries (Pecari tajacu. The monthly records of the weight of 10 captive female collared peccaries over a period of two years in the Brazilian Amazon Region were used. The growth models used were the Von Bertalanffy, Brody, Gompertz and Logistic. The parameters were estimated by using the NLIN procedure from the SAS application. The criteria used to verify the adjustment of the models were: asymptotic standard deviation (ASD; coefficient of determination (R²; average absolute residual deviation (ARD and the asymptotic rate (AR. The Brody model and the Logistic model estimated the highest (19.44kg and the lowest (19.18kg asymptotic weight (A, indicating the lowest (0.0070kg/day and the highest (0.0121kg/day maturation rate (K. These results and the coefficients of phenotypic correlation that varied from -0.75 and -0.47 confirmed the antagonistic nature between these parameters. The Brody model estimated the lower value for ARD, a limiting factor for describing the lowest value for AR through this model. The Brody model showed the best adjustment for AR, although the other models also showed a suitable adjustment to the weight data of said species/gender. Based on the AR obtained in this work, the Brody model is recommended for adjusting the growth curve of the female collared peccaries. Depending on the estimated values, especially for K, this trait can be included in a selection index.
Modeling experience curves in MERGE (model for evaluating regional and global effects)
Energy Technology Data Exchange (ETDEWEB)
Kypreos, S. [Paul Scherrer Institute, Villigen (Switzerland). Energy Systems Analysis Group
2005-11-01
The Swiss National Centre of Competence in Research on Climate aims to explore the predictability, variability, and risk of climate change. The Paul Scherrer Institute, which is involved in this program, uses integrated assessment models to simulate policies for climate-change mitigation under uncertainty. We report here selected results of the model for evaluating the regional and global effects (MERGEs) of greenhouse-gas emissions with endogenous technological learning (ETL), known as MERGE-ETL. The novelty of the approach is the application of an heuristic algorithm to solve the non-linear and non-convex MERGE problem where 'learning-by-doing' is adopted for a set of energy technologies. The study presents numerical examples showing the implications of endogenous-learning for the timing of carbon-abatement that stabilizes carbon concentrations (e.g. at 550 ppmv), as well as the implications of this in terms of cost/benefit (C/B) analysis. The endogenous-learning formulation is contrasted with the version of the model without ETL. The improved methodology indicates a potential for significant reduction in carbon-abatement cost and economic losses. The method, which is basically in favor of late actions in abatement, implicitly assumes early R and D support and learning investments in carbon-free systems to help these new technologies follow their learning curves. The endogenous treatment of learning already shows significant reductions of carbon emissions in the baseline case and indicates that low-carbon concentrations and improved environmental performance can be obtained when policies are followed that compensate for externalities related to climate change. More precisely, MERGE-ETL gives C/B-optimal carbon-emission trajectories near the 590-ppmv-concentration level. Moreover, the imposition of constraints on the rate of temperature change (e.g. 0.21{sup o}C per decade) demands early actions in carbon mitigation. (author)
de Marco, E.; Tema, E.; Lanos, P.; Kondopoulou, D.
2009-12-01
A total of 64 Greek archaeomagnetic directional data have been used for the establishment of the variation of the Earth’s magnetic field in Greece over the past 4500 years. Most of the data come from archaeological material but some data from Santorini lava flows are also included. The data ages range from Minoan times (~2500 BC) up to the last century with a gap around 10th to 6th century BC. All data have been relocated to Athens (37.97° N, 23.72° E) using the virtual geomagnetic pole method. Data coming from direct measurements available in Greece for the last four centuries have been also added. The secular variation (SV) curves for declination and inclination have been obtained using hierarchical Bayesian modelling. For comparison, the dataset has been also analysed using the bi-variate moving average window technique with 150 years time window shifted by 75 years. The obtained smoothed curves accompanied by a 95 % confidence envelope are compared with archaeomagnetic data from Mediterranean area and with SV curves from nearby countries. The Greek curves have also been compared with the predictions of the SCHA.DIF.3K regional and the CALS7K and ARCH3K global geomagnetic field models. Despite the differences recognised between these models, the Greek archaeomagnetic SV curve is in reasonably good agreement with their basic trends. The proposed directional SV curve can contribute, together with the intensity SV curve previously published for Greece, to the reliable archaeomagnetic dating of Greek artefacts based on the full description of the Earth’s magnetic field (declination, inclination, intensity). It is clear that the continuous update of the dataset with new results from well-dated archaeological material will increase the precision of the SV curve, especially for the time periods poorly covered by data.
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M. Sivapalan
2012-11-01
Full Text Available The goal of this paper is to explore the process controls underpinning regional patterns of variations of streamflow regime behavior, i.e., the mean seasonal variation of streamflow within the year, across the continental United States. The ultimate motivation is to use the resulting process understanding to generate insights into the physical controls of another signature of streamflow variability, namely the flow duration curve (FDC. The construction of the FDC removes the time dependence of flows. Thus in order to better understand the physical controls in regions that exhibit strong seasonal dependence, the regime curve (RC, which is closely connected to the FDC, is studied in this paper and later linked back to the FDC. To achieve these aims a top-down modeling approach is adopted; we start with a simple two-stage bucket model, which is systematically enhanced through addition of new processes on the basis of model performance assessment in relation to observations, using rainfall-runoff data from 197 United States catchments belonging to the MOPEX dataset. Exploration of dominant processes and the determination of required model complexity are carried out through model-based sensitivity analyses, guided by a performance metric. Results indicated systematic regional trends in dominant processes: snowmelt was a key process control in cold mountainous catchments in the north and north-west, whereas snowmelt and vegetation cover dynamics were key controls in the north-east; seasonal vegetation cover dynamics (phenology and interception were important along the Appalachian mountain range in the east. A simple two-bucket model (with no other additions was found to be adequate in warm humid catchments along the west coast and in the south-east, with both regions exhibiting strong seasonality, whereas much more complex models are needed in the dry south and south-west. Agricultural catchments in the mid-west were found to be difficult to predict
Biochar effects on wet and dry regions of the soil water retention curve of a sandy loam
DEFF Research Database (Denmark)
Arthur, Emmanuel; Moldrup, Per; Sun, Zhencai
2014-01-01
Reported beneficial effects of biochar on soil physical properties and processes include decreased soil density, and increased soil water transport, water holding capacity and retention (mainly for the wet region). Research is limited on biochar effects on the full soil water retention curve (wet...... and dry regions) for a given soil and biochar amendment scenarios. This study evaluates how biochar applied to a sandy loam field at rates from 0 to 50 Mg ha−1 yr–1 in 2011, 2012, or both years (2011+2012) influences the full water retention curve. Inorganic fertilizer and pig slurry were added to all...... treatments. Six months after the last biochar application, intact and disturbed soil samples were collected for analyses. Soil water retention was measured from −1 kPa to −100 kPa using tension tables and ceramic plates and from −10 MPa to −480 MPa using a Vapor Sorption Analyzer. Soil specific area...
Coopersmith, E.; Yaeger, M. A.; Ye, S.; Cheng, L.; Sivapalan, M.
2012-11-01
Predictions of hydrological responses in ungauged catchments can benefit from a classification scheme that can organize and pool together catchments that exhibit a level of hydrologic similarity, especially similarity in some key variable or signature of interest. Since catchments are complex systems with a level of self-organization arising from co-evolution of climate and landscape properties, including vegetation, there is much to be gained from developing a classification system based on a comparative study of a population of catchments across climatic and landscape gradients. The focus of this paper is on climate seasonality and seasonal runoff regime, as characterized by the ensemble mean of within-year variation of climate and runoff. The work on regime behavior is part of an overall study of the physical controls on regional patterns of flow duration curves (FDCs), motivated by the fact that regime behavior leaves a major imprint upon the shape of FDCs, especially the slope of the FDCs. As an exercise in comparative hydrology, the paper seeks to assess the regime behavior of 428 catchments from the MOPEX database simultaneously, classifying and regionalizing them into homogeneous or hydrologically similar groups. A decision tree is developed on the basis of a metric chosen to characterize similarity of regime behavior, using a variant of the Iterative Dichotomiser 3 (ID3) algorithm to form a classification tree and associated catchment classes. In this way, several classes of catchments are distinguished, in which the connection between the five catchments' regime behavior and climate and catchment properties becomes clearer. Only four similarity indices are entered into the algorithm, all of which are obtained from smoothed daily regime curves of climatic variables and runoff. Results demonstrate that climate seasonality plays the most significant role in the classification of US catchments, with rainfall timing and climatic aridity index playing somewhat
Local Condensation Curve from Dropwise to Glacial Region on Large Vertical Surface
Haraguchi, Tadao; Shimada, Ryohachi; Takeyama, Toshiro
The existence of several regimes of condensation heat transfer is well known. Regimes are given academic names as dropwise, transition, film and glacial condensation along the condensation curve showing the relationship between heat flux and surface subcooling. In case of comparatively large vertical surface, the lower part on the gravitational direction is affected by condensate from the upper part, and will be covered by water stream like a rivulet. It has no longer an existence as dropwise condition, and it is absolutely impossible that heat transfer problems under constant temperature or constant heat flux take place. The reason is why as follows, heat transfer of film condensation is some orders of magnitude less than dropwise condensation, and various regimes exist together simultaneously. In the present paper we shall try to observe the coexisting appearance of regimes in steam condensation at atmospheric pressure and make researches in the local condensation curve from top to bottom on the same surface, that is divided into eight parts in the rear side. The main results are shown as follows (1) Enhancement of heat transfer by wiping of drops appears toward somewhat lower position from top. (2) Frazil ice is observed in the supercooled liquid film flowing down on glacial condensation. (3) The regime of glacial condensation describes a thermal hysteresis loop.
Ferro, A Arellano; Calderón, J H; Kains, N
2014-01-01
CCD time-series observations of the central region of the globular cluster NGC~3201 were obtained with the aim of performing the Fourier decomposition of the light curves of the RR~Lyrae stars present in that field. This procedure gave the mean values, for the metallicity, of [Fe/H]$_{ZW}=-1.483 \\pm 0.006$ (statistical) $\\pm 0.090$ (systematical), and for the distance, $5.000 \\pm 0.001$~kpc (statistical) $\\pm 0.220$ (systematical). The values found from two RRc stars are consistent with those derived previously. The differential reddening of the cluster was investigated and individual reddenings for the RR Lyrae stars were estimated from their $V-I$ curves. We found an average value of $E(B-V)= 0.23 \\pm 0.02$. An investigation of the light curves of stars in the {\\it blue stragglers} region led to the discovery of three new SX~Phe stars. The period-luminosity relation of the SX~Phe stars was used for an independent determination of the distance to the cluster and of the individual reddenings. We found a dista...
Analysis of MOST light curves of five young stars in Taurus-Auriga and Lupus~3 Star Forming Regions
Siwak, Michal; Matthews, Jaymie M; Kuschnig, Rainer; Guenther, David B; Moffat, Anthony F J; Sasselov, Dimitar; Weiss, Werner W
2011-01-01
Continuous photometric observations of five young stars obtained by the MOST satellite in 2009 and 2010 in the Taurus and Lupus star formation regions are presented. Using light curve modelling under the assumption of internal invariability of spots, we obtained small values of the solar-type differential-rotation parameter (k=0.0005-0.009) for three spotted weak-line T Tau stars, V410 Tau, V987 Tau and Lupus 3-14; for another spotted WTTS, Lupus 3-48, the data are consistent with a rigidly rotating surface (k=0). Three flares of similar rise (4 min 30 sec) and decay (1 h 45 min) times were detected in the light curve of Lupus 3-14. The brightness of the classical T Tau star RY Tau continuously decreased over 3 weeks of its observations with a variable modulation not showing any obvious periodic signal.
The learning curve for laparoscopic colectomy in colorectal cancer at a new regional hospital
Directory of Open Access Journals (Sweden)
Kuei-Yen Tsai
2016-01-01
Conclusion: Laparoscopic colectomy for colorectal cancer in a new regional hospital is feasible and safe. It does not need additional time for learning. Laparoscopic sigmoidectomy can be considered as the initial surgery for a trainee.
Cao, Xinhua; Xu, Xiaoyin; Voss, Stephan
2017-03-01
In this paper, we describe an enhanced DICOM Secondary Capture (SC) that integrates Image Quantification (IQ) results, Regions of Interest (ROIs), and Time Activity Curves (TACs) with screen shots by embedding extra medical imaging information into a standard DICOM header. A software toolkit of DICOM IQSC has been developed to implement the SC-centered information integration of quantitative analysis for routine practice of nuclear medicine. Primary experiments show that the DICOM IQSC method is simple and easy to implement seamlessly integrating post-processing workstations with PACS for archiving and retrieving IQ information. Additional DICOM IQSC applications in routine nuclear medicine and clinic research are also discussed.
Ye, S.; Li, H.; Ali, M.; Huang, M.; Leung, L.; Sivapalan, M.
2012-12-01
Subsurface runoff is an important component of water balance especially in steep forested areas. It has been shown that the subsurface runoff parameterization significantly affects the partitioning of water budget, and subsequently the simulations of energy budget, carbon cycle and atmospheric cycle in land surface models such as the Community Land Model (CLM). A robust parameterization of subsurface runoff within land surface models, however, remains a grand challenge. This work is a first major step towards developing empirical relationships between the parameters of a generalized power-law form of TOPMODEL and measurable data such as climate, soil, vegetation and topographic conditions. We analyzed the flow data from over 300 MOPEX catchments across the continental United States and extracted the values of the recession curve coefficient and exponent in the form of the slope-recession curve, i.e., - dQ/dt vs Q for each catchment. By improving the estimation of soil properties within MOPEX database such as the mean and variance of saturated hydraulic conductivity and porosity based on the SSURGO dataset for 30 selected catchments across the continent covering a range of climate conditions, we examined the regional patterns of recession curve coefficient and exponent. Our results suggest that the recession curve exponent is higher in the eastern humid Appalachian forested catchments but relatively smaller in the central flat catchments. We further explored the possible linkages between the exponent and coefficient and climate and landscape properties through data analyses and numerical experiments. Results of this study will serve as the basis for improving subsurface representations in CLM.
Empirical rainfall thresholds and copula based IDF curves for shallow landslides and flash floods
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
Geng, Jianzhao; Coombs, T. A.
2016-09-01
High-T c superconducting (HTS) flux pumps are capable of compensating the persistent current decay in HTS magnets without electrical contact. In this paper, following work on a low-T c superconducting self-switching flux pump, we propose a new HTS flux pump by directly driving a high-T c superconductor into the flux flow region in the E- J curve. The flux pump consists of a transformer which has a superconducting secondary winding shorted by an YBCO-coated conductor bridge. A high alternating current with a much higher positive peak value than the negative peak value is induced in the secondary winding. The current always drives the bridge superconductor into the flux flow region only at around its positive peak value, thus resulting in flux pumping. The proposed flux pump is much simpler than existing HTS flux pumps.
Ferreira, Abílio G T; Henrique, Douglas S; Vieira, Ricardo A M; Maeda, Emilyn M; Valotto, Altair A
2015-03-01
The objective of this study was to evaluate four mathematical models with regards to their fit to lactation curves of Holstein cows from herds raised in the southwestern region of the state of Parana, Brazil. Initially, 42,281 milk production records from 2005 to 2011 were obtained from "Associação Paranaense de Criadores de Bovinos da Raça Holandesa (APCBRH)". Data lacking dates of drying and total milk production at 305 days of lactation were excluded, resulting in a remaining 15,142 records corresponding to 2,441 Holstein cows. Data were sorted according to the parity order (ranging from one to six), and within each parity order the animals were divided into quartiles (Q25%, Q50%, Q75% and Q100%) corresponding to 305-day lactation yield. Within each parity order, for each quartile, four mathematical models were adjusted, two of which were predominantly empirical (Brody and Wood) whereas the other two presented more mechanistic characteristics (models Dijkstra and Pollott). The quality of fit was evaluated by the corrected Akaike information criterion. The Wood model showed the best fit in almost all evaluated situations and, therefore, may be considered as the most suitable model to describe, at least empirically, the lactation curves of Holstein cows raised in Southwestern Parana.
Directory of Open Access Journals (Sweden)
Abílio G.T. Ferreira
2015-03-01
Full Text Available The objective of this study was to evaluate four mathematical models with regards to their fit to lactation curves of Holstein cows from herds raised in the southwestern region of the state of Parana, Brazil. Initially, 42,281 milk production records from 2005 to 2011 were obtained from "Associação Paranaense de Criadores de Bovinos da Raça Holandesa (APCBRH". Data lacking dates of drying and total milk production at 305 days of lactation were excluded, resulting in a remaining 15,142 records corresponding to 2,441 Holstein cows. Data were sorted according to the parity order (ranging from one to six, and within each parity order the animals were divided into quartiles (Q25%, Q50%, Q75% and Q100% corresponding to 305-day lactation yield. Within each parity order, for each quartile, four mathematical models were adjusted, two of which were predominantly empirical (Brody and Wood whereas the other two presented more mechanistic characteristics (models Dijkstra and Pollott. The quality of fit was evaluated by the corrected Akaike information criterion. The Wood model showed the best fit in almost all evaluated situations and, therefore, may be considered as the most suitable model to describe, at least empirically, the lactation curves of Holstein cows raised in Southwestern Parana.
Flood risk assessment at the regional scale: Computational challenges and the monster of uncertainty
Efstratiadis, Andreas; Papalexiou, Simon-Michael; Markonis, Yiannis; Koukouvinos, Antonis; Vasiliades, Lampros; Papaioannou, George; Loukas, Athanasios
2016-04-01
We present a methodological framework for flood risk assessment at the regional scale, developed within the implementation of the EU Directive 2007/60 in Greece. This comprises three phases: (a) statistical analysis of extreme rainfall data, resulting to spatially-distributed parameters of intensity-duration-frequency (IDF) relationships and their confidence intervals, (b) hydrological simulations, using event-based semi-distributed rainfall-runoff approaches, and (c) hydraulic simulations, employing the propagation of flood hydrographs across the river network and the mapping of inundated areas. The flood risk assessment procedure is employed over the River Basin District of Thessaly, Greece, which requires schematization and modelling of hundreds of sub-catchments, each one examined for several risk scenarios. This is a challenging task, involving multiple computational issues to handle, such as the organization, control and processing of huge amount of hydrometeorological and geographical data, the configuration of model inputs and outputs, and the co-operation of several software tools. In this context, we have developed supporting applications allowing massive data processing and effective model coupling, thus drastically reducing the need for manual interventions and, consequently, the time of the study. Within flood risk computations we also account for three major sources of uncertainty, in an attempt to provide upper and lower confidence bounds of flood maps, i.e. (a) statistical uncertainty of IDF curves, (b) structural uncertainty of hydrological models, due to varying anteceded soil moisture conditions, and (c) parameter uncertainty of hydraulic models, with emphasis to roughness coefficients. Our investigations indicate that the combined effect of the above uncertainties (which are certainly not the unique ones) result to extremely large bounds of potential inundation, thus rising many questions about the interpretation and usefulness of current flood
Cheng, L.; Yaeger, M.; Viglione, A.; Coopersmith, E.; Ye, S.; Sivapalan, M.
2012-11-01
The flow duration curve (FDC) is a classical method used to graphically represent the relationship between the frequency and magnitude of streamflow. In this sense it represents a compact signature of temporal runoff variability that can also be used to diagnose catchment rainfall-runoff responses, including similarity and differences between catchments. This paper is aimed at extracting regional patterns of the FDCs from observed daily flow data and elucidating the physical controls underlying these patterns, as a way to aid towards their regionalization and predictions in ungauged basins. The FDCs of total runoff (TFDC) using multi-decadal streamflow records for 197 catchments across the continental United States are separated into the FDCs of two runoff components, i.e., fast flow (FFDC) and slow flow (SFDC). In order to compactly display these regional patterns, the 3-parameter mixed gamma distribution is employed to characterize the shapes of the normalized FDCs (i.e., TFDC, FFDC and SFDC) over the entire data record. This is repeated to also characterize the between-year variability of "annual" FDCs for 8 representative catchments chosen across a climate gradient. Results show that the mixed gamma distribution can adequately capture the shapes of the FDCs and their variation between catchments and also between years. Comparison between the between-catchment and between-year variability of the FDCs revealed significant space-time symmetry. Possible relationships between the parameters of the fitted mixed gamma distribution and catchment climatic and physiographic characteristics are explored in order to decipher and point to the underlying physical controls. The baseflow index (a surrogate for the collective impact of geology, soils, topography and vegetation, as well as climate) is found to be the dominant control on the shapes of the normalized TFDC and SFDC, whereas the product of maximum daily precipitation and the fraction of non-rainy days was found to
Bezak, Nejc; Šraj, Mojca; Mikoš, Matjaž
2016-10-01
Floods, landslides and debris flows are natural events that occur all over the world and are often induced by extreme rainfall conditions. Several extreme events occurred in Slovenia (Europe) in the last 25 years that caused 18 casualties and approximately 500 million Euros of economic loss. The intensity-duration-frequency (IDF) relationship was constructed using the Frank copula function for several rainfall stations using high-resolution rainfall data with an average subsample length of 34 years. The empirical rainfall threshold curves were also evaluated for selected extreme events. Post-event analyses showed that rainfall characteristics triggering flash floods and landslides are different. The sensitivity analysis results indicate that the inter-event time definition (IETD) and subsample definition methodology can have a significant influence on the position of rainfall events in the intensity-duration space, the constructed IDF curves and on the relationship between the empirical rainfall threshold curves and the IDF curves constructed using the copula approach. Furthermore, a combination of several empirical rainfall thresholds with an appropriate high-density rainfall measurement network can be used as part of the early warning system of the initiation of landslides and debris flows. However, different rainfall threshold curves should be used for lowland and mountainous areas in Slovenia.
Decat, E.; van Mechelen, E.; Saerens, B.; Vermeulen, S.J.T.; Boekhout, T.; de Blaiser, S.; Vaneechoutte, M.; Deschaght, P.
2013-01-01
Rapid identification of clinically important yeasts can facilitate the initiation of anti-fungal therapy, since susceptibility is largely species-dependent. We evaluated melting peak and melting curve analysis of the internally transcribed spacer region 2 fragment (ITS2-MCA) as an identification too
Decat, E.; van Mechelen, E.; Saerens, B.; Vermeulen, S.J.T.; Boekhout, T.; de Blaiser, S.; Vaneechoutte, M.; Deschaght, P.
2013-01-01
Rapid identification of clinically important yeasts can facilitate the initiation of anti-fungal therapy, since susceptibility is largely species-dependent. We evaluated melting peak and melting curve analysis of the internally transcribed spacer region 2 fragment (ITS2-MCA) as an identification
Franckowiak, A.; Stanek, K. Z.; Kochanek, C. S.; Thompson, T. A.; Holoien, T. W.-S.; Shappee, B. J.; Prieto, J. L.; Dong, Subo
2017-09-01
Archival ASAS-SN (Shappee et al. 2014) data show an increased optical activity of the blazar TXS 0506+056, which is located inside the error region of the high-energy neutrino candidate IceCube-170922A, and was found to be in a flaring state by Fermi-LAT (ATel #10791), and it was also observed by Swift Using ASAS-SN Sky Patrol public all-sky light curve interface (Kochanek et al. 2017), we retrieved 200-day light curve of TXS 0506+056, showing a rise of 0.5 mag in V-band over the last 50 days.
A marginal abatement cost curve (MACC) traces out the relationship between the quantity of pollution abated and the marginal cost of abating each additional unit. In the context of air quality management, MACCs typically are developed by sorting end-of-pipe controls by their resp...
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Saint Christopher P
2007-03-01
Full Text Available Abstract Background DNA melting curve analysis using double-stranded DNA-specific dyes such as SYTO9 produce complex and reproducible melting profiles, resulting in the detection of multiple melting peaks from a single amplicon and allowing the discrimination of different species. We compare the melting curves of several Naegleria and Cryptosporidium amplicons generated in vitro with in silico DNA melting simulations using the programs POLAND and MELTSIM., then test the utility of these programs for assay design using a genetic marker for toxin production in cyanobacteria. Results The SYTO9 melting curve profiles of three species of Naegleria and two species of Cryptosporidium were similar to POLAND and MELTSIM melting simulations, excepting some differences in the relative peak heights and the absolute melting temperatures of these peaks. MELTSIM and POLAND were used to screen sequences from a putative toxin gene in two different species of cyanobacteria and identify regions exhibiting diagnostic melting profiles. For one of these diagnostic regions the POLAND and MELTSIM melting simulations were observed to be different, with POLAND more accurately predicting the melting curve generated in vitro. Upon further investigation of this region with MELTSIM, inconsistencies between the melting simulation for forward and reverse complement sequences were observed. The assay was used to accurately type twenty seven cyanobacterial DNA extracts in vitro. Conclusion Whilst neither POLAND nor MELTSIM simulation programs were capable of exactly predicting DNA dissociation in the presence of an intercalating dye, the programs were successfully used as tools to identify regions where melting curve differences could be exploited for diagnostic melting curve assay design. Refinements in the simulation parameters would be required to account for the effect of the intercalating dye and salt concentrations used in real-time PCR. The agreement between the melting
Lactation curve of cross-bred buffalo under two production systems in the Amazonian region of Brazil
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A.C. Ribeiro Neto
2010-02-01
Full Text Available This study was conducted at the Agroforestry Research Center of EMBRAPA (CPAFRO, Rondônia, Brazil, to evaluate the lactation curve of crosss-bred buffalo [Murrah (M, Mediterranean (Me and Jafarabadi(J] under two production systems. Production system one (PS1 corresponded to the period of 1984 to 1998 where animals (4471 observation were milked once a day and received only pasture without supplementation. Production system two (PS2 corresponded to the period of 1999 to 2002 where animals (458 observations were milked twice daily with concentrate supplementation to pasture. Eight mathematical functions were used: Inverse Polynomial, Linear Hyperbolic, Incomplete Gamma, Logarithmic, Logarithmic Quadratic, Linear, Quadratic and Jenkins & Ferrel. Statistical analysis was conducted using PROC NLIN of SAS (2005. Results showed that for both production systems, Incomplete Gama was the best function to describe the lactation curve. Values of coefficient of determination, standard-deviation, coefficient of variation and standard-error were 95%, 0.068, 7.20, and 0.003, respectively. The corresponding values for PS2 were 96%, 0.200, 2.12, and 0.003. Values of the lactation curve parameters (a, b, and c for PS1 and PS2, respectively, were (a 7.0035923 and 10.9209, (b -0.1080043 and -0.1614882, (c 0.0434868 and 0.0679365.
Directory of Open Access Journals (Sweden)
Shima Fayaz
2012-01-01
Full Text Available Homologous recombination (HR is the major pathway for repairing double strand breaks (DSBs in eukaryotes and XRCC2 is an essential component of the HR repair machinery. To evaluate the potential role of mutations in gene repair by HR in individuals susceptible to differentiated thyroid carcinoma (DTC we used high resolution melting (HRM analysis, a recently introduced method for detecting mutations, to examine the entire XRCC2 coding region in an Iranian population. HRM analysis was used to screen for mutations in three XRCC2 coding regions in 50 patients and 50 controls. There was no variation in the HRM curves obtained from the analysis of exons 1 and 2 in the case and control groups. In exon 3, an Arg188His polymorphism (rs3218536 was detected as a new melting curve group (OR: 1.46; 95%CI: 0.432-4.969; p = 0.38 compared with the normal melting curve. We also found a new Ser150Arg polymorphism in exon 3 of the control group. These findings suggest that genetic variations in the XRCC2 coding region have no potential effects on susceptibility to DTC. However, further studies with larger populations are required to confirm this conclusion.
A Bayesian beta distribution model for estimating rainfall IDF curves in a changing climate
Lima, Carlos H. R.; Kwon, Hyun-Han; Kim, Jin-Young
2016-09-01
The estimation of intensity-duration-frequency (IDF) curves for rainfall data comprises a classical task in hydrology studies to support a variety of water resources projects, including urban drainage and the design of flood control structures. In a changing climate, however, traditional approaches based on historical records of rainfall and on the stationary assumption can be inadequate and lead to poor estimates of rainfall intensity quantiles. Climate change scenarios built on General Circulation Models offer a way to access and estimate future changes in spatial and temporal rainfall patterns at the daily scale at the utmost, which is not as fine temporal resolution as required (e.g. hours) to directly estimate IDF curves. In this paper we propose a novel methodology based on a four-parameter beta distribution to estimate IDF curves conditioned on the observed (or simulated) daily rainfall, which becomes the time-varying upper bound of the updated nonstationary beta distribution. The inference is conducted in a Bayesian framework that provides a better way to take into account the uncertainty in the model parameters when building the IDF curves. The proposed model is tested using rainfall data from four stations located in South Korea and projected climate change Representative Concentration Pathways (RCPs) scenarios 6 and 8.5 from the Met Office Hadley Centre HadGEM3-RA model. The results show that the developed model fits the historical data as good as the traditional Generalized Extreme Value (GEV) distribution but is able to produce future IDF curves that significantly differ from the historically based IDF curves. The proposed model predicts for the stations and RCPs scenarios analysed in this work an increase in the intensity of extreme rainfalls of short duration with long return periods.
Santos-Sanz, P.; Lellouch, E.; Groussin, O.; Lacerda, P.; Müller, T. G.; Ortiz, J. L.; Kiss, C.; Vilenius, E.; Stansberry, J.; Duffard, R.; Fornasier, S.; Jorda, L.; Thirouin, A.
2017-08-01
Context. Time series observations of the dwarf planet Haumea and the Plutinos 2003 VS2 and 2003 AZ84 with Herschel/PACS are presented in this work. Thermal emission of these trans-Neptunian objects (TNOs) were acquired as part of the "TNOs are Cool" Herschel Space Observatory key programme. Aims: We search for the thermal light curves at 100 and 160 μm of Haumea and 2003 AZ84, and at 70 and 160 μm for 2003 VS2 by means of photometric analysis of the PACS data. The goal of this work is to use these thermal light curves to obtain physical and thermophysical properties of these icy Solar System bodies. Methods: When a thermal light curve is detected, it is possible to derive or constrain the object thermal inertia, phase integral and/or surface roughness with thermophysical modeling. Results: Haumea's thermal light curve is clearly detected at 100 and 160 μm. The effect of the reported dark spot is apparent at 100 μm. Different thermophysical models were applied to these light curves, varying the thermophysical properties of the surface within and outside the spot. Although no model gives a perfect fit to the thermal observations, results imply an extremely low thermal inertia (0.73) for Haumea's surface. We note that the dark spot region appears to be only weakly different from the rest of the object, with modest changes in thermal inertia and/or phase integral. The thermal light curve of 2003 VS2 is not firmly detected at 70 μm and at 160 μm but a thermal inertia of (2 ± 0.5) MKS can be derived from these data. The thermal light curve of 2003 AZ84 is not firmly detected at 100 μm. We apply a thermophysical model to the mean thermal fluxes and to all the Herschel/PACS and Spitzer/MIPS thermal data of 2003 AZ84, obtaining a close to pole-on orientation as the most likely for this TNO. Conclusions: For the three TNOs, the thermal inertias derived from light curve analyses or from the thermophysical analysis of the mean thermal fluxes confirm the generally small
Manti, L.; Durante, M.; Grossi, G.; Pugliese, M.; Scampoli, P.; Gialanella, G.
2007-06-01
Radiotherapy with high-energy carbon ion beams can be more advantageous compared to photons because of better physical dose distribution and higher biological efficiency in tumour cell sterilization. Despite enhanced normal tissue sparing, damage incurred by normal cells at the beam entrance is unavoidable and may affect the progeny of surviving cells in the form of inheritable cytogenetic alterations. Furthermore, the quality of the beam along the Bragg curve is modified by nuclear fragmentation of projectile and target nuclei in the body. We present an experimental approach based on the use of a polymethylmethacrylate (PMMA) phantom that allows the simultaneous exposure to a particle beam of several biological samples positioned at various depths along the beam path. The device was used to measure the biological effectiveness of a 60 MeV/amu carbon-ion beam at inducing chromosomal aberrations in G0-human peripheral blood lymphocytes. Chromosome spreads were obtained from prematurely condensed cells and all structural aberration types were scored in Fluorescence in situ Hybridization (FISH)-painted chromosomes 1 and 2. Our results show a marked increase with depth in the aberration frequency prior to the Bragg peak, which is consistent with a linear energy transfer (LET)-dependent increase in biological effectiveness.
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Tomirotti, M. [Milan Univ., Milan (Italy). Dipt. di Ingegneria Idraulica, Ambientale e del Rilevamento
2001-10-01
In this paper a regional estimation model of the flood duration frequency reduction curves of the italian rivers is proposed; the model is based on the estimation of peak flood discharge and instantaneous-daily flood peak ratio of the river basin. While for the estimation of the first quantity a great amount of papers is available in literature less attention has been devoted to the second one. Thus, a regional estimation model of the instantaneous-daily flood peak ratio of the Italian river basins has been formulated, employing for the calibration a set of data referring to 212 gauging stations belonging to the entire territory of the italian Country and characterized by twenty years of observations; the domain of validity of the model covers the most part of the territory of the italian Country. On the basis of the results of the analysis, the methodology of design of flood control reservoirs presented in previous papers has been re-examined and becomes applicable to non-gauged sites. [Italian] Nella presente memoria viene proposto un modello di stima indiretta delle curve di riduzione dei colmi di piena dei corsi d'acqua italiani basato sulla stima regionale delle portate al colmo e del coefficiente di punta del bacino. Mentre per la stima della prima grandezza e' disponibile un'amplissima mole di lavori, minore attenzione e' stata rivolta nella letteratura tecnica alla seconda. E' stato percio' sviluppato un modello di stima regionale del coefficiente di punta dei corsi d'acqua italiani, utilizzando per la taratura i dati relativi a 212 stazioni idrometrografiche distribuite sull'intero territorio nazionale e caratterizzate dal almeno venti anni di osservazioni; il dominio di validita' del modello sviluppato ricopre la quasi totalita' del territorio nazionale. Sulla base dei risultati dell'analisi e' stata infine ripresa la metodologia semplificata per la determinazione dei volumi da assegnare alle
Lomer, M.; Galindez, C. A.; Quintela, M. A.; Quintela, A.; Mirapeix, J.; Lopez-Higuera, J. M.
2008-04-01
A refractometric sensor that uses the transition region of a U-bent Plastic Optical Fiber (POF) when it is polished laterally is presented. By polishing a lateral segment of the fiber, a part of the plastic optical fiber core is removed and an elliptical surface is formed on the bend. It is found that that the polishing with an angle equals to the critical angle of a straight optical fiber the sensitivity of this transducer structure is enhanced. Then, the incident light is totally reflected and the transition losses decrease locally. In addition, the sensitivity increases compared to the polishing in the region of bending losses. The proposed transducer is successfully checked with experimental measurements and different kinds of liquids. Potential applications are suggested.
Kouadio, Louis; Duveiller, Grégory; Djaby, Bakary; El Jarroudi, Moussa; Defourny, Pierre; Tychon, Bernard
2012-08-01
Earth observation data, owing to their synoptic, timely and repetitive coverage, have been recognized as a valuable tool for crop monitoring at different levels. At the field level, the close correlation between green leaf area (GLA) during maturation and grain yield in wheat revealed that the onset and rate of senescence appeared to be important factors for determining wheat grain yield. Our study sought to explore a simple approach for wheat yield forecasting at the regional level, based on metrics derived from the senescence phase of the green area index (GAI) retrieved from remote sensing data. This study took advantage of recent methodological improvements in which imagery with high revisit frequency but coarse spatial resolution can be exploited to derive crop-specific GAI time series by selecting pixels whose ground-projected instantaneous field of view is dominated by the target crop: winter wheat. A logistic function was used to characterize the GAI senescence phase and derive the metrics of this phase. Four regression-based models involving these metrics (i.e., the maximum GAI value, the senescence rate and the thermal time taken to reach 50% of the green surface in the senescent phase) were related to official wheat yield data. The performances of such models at this regional scale showed that final yield could be estimated with an RMSE of 0.57 ton ha-1, representing about 7% as relative RMSE. Such an approach may be considered as a first yield estimate that could be performed in order to provide better integrated yield assessments in operational systems.
Long-period oscillations of active region patterns: least-squares mapping on second-order curves
Dumbadze, G; Kukhianidze, V; Ramishvili, G; Zaqarashvili, T V; Khodachenko, M; Gurgenashvili, E; Poedts, S; De Causmaecker, P
2016-01-01
Active regions (ARs) are the main sources of variety in solar dynamic events. Automated detection and identification tools need to be developed for solar features for a deeper understanding of the solar cycle. Of particular interest here are the dynamical properties of the ARs, regardless of their internal structure and sunspot distribution. We studied the oscillatory dynamics of two ARs: NOAA 11327 and NOAA 11726 using two different methods of pattern recognition. We developed a novel method of automated AR border detection and compared it to an existing method for the proof-of-concept. The first method uses least-squares fitting on the smallest ellipse enclosing the AR, while the second method applies regression on the convex hull.} After processing the data, we found that the axes and the inclination angle of the ellipse and the convex hull oscillate in time. These oscillations are interpreted as the second harmonic of the standing long-period kink oscillations (with the node at the apex) of the magnetic f...
A Unified Theory of Rainfall Extremes, Rainfall Excesses, and IDF Curves
Veneziano, D.; Yoon, S.
2012-04-01
Extreme rainfall events are a key component of hydrologic risk management and design. Yet, a consistent mathematical theory of such extremes remains elusive. This study aims at laying new statistical foundations for such a theory. The quantities of interest are the distribution of the annual maximum, the distribution of the excess above a high threshold z, and the intensity-duration-frequency (IDF) curves. Traditionally, the modeling of annual maxima and excesses is based on extreme value (EV) and extreme excess (EE) theories. These theories establish that the maximum of n iid variables is attracted as n →∞ to a generalized extreme value (GEV) distribution with a certain index k and the distribution of the excess is attracted as z →∞ to a generalized Pareto distribution with the same index. The empirical value of k tends to decrease as the averaging duration d increases. To a first approximation, the IDF intensities scale with d and the return period T . Explanations for this approximate scaling behavior and theoretical predictions of the scaling exponents have emerged over the past few years. This theoretical work has been largely independent of that on the annual maxima and the excesses. Deviations from exact scaling include a tendency of the IDF curves to converge as d and T increase. To bring conceptual clarity and explain the above observations, we analyze the extremes of stationary multifractal measures, which provide good representations of rainfall within storms. These extremes follow from large deviation theory rather than EV/EE theory. A unified framework emerges that (a) encompasses annual maxima, excesses and IDF values without relying on EV or EE asymptotics, (b) predicts the index k and the IDF scaling exponents, (c) explains the dependence of k on d and the deviations from exact scaling of the IDF curves, and (d) explains why the empirical estimates of k tend to be positive (in the Frechet range) while, based on frequently assumed marginal
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M. Sivapalan
2012-06-01
Full Text Available The goal of this paper is to explore the process controls underpinning regional patterns of variations of runoff regime behavior, i.e., the mean seasonal variation of runoff within the year, across the continental United States. The ultimate motivation is to use the resulting process understanding to generate insights into the physical controls of Flow Duration Curves, in view of the close connection between these two alternative signatures of runoff variability. To achieve these aims a top-down modeling approach is adopted; we start with a simple two-stage bucket model, which is systematically enhanced through addition of new processes on the basis of model performance assessment in relation to observations, using rainfall-runoff data from 197 United States catchments belonging to the MOPEX dataset. Exploration of dominant processes and the determination of required model complexity are carried out through model-based sensitivity analyses, guided by a performance metric. Results indicated systematic regional trends in dominant processes: snowmelt was a key process control in cold mountainous catchments in the north and north-west, whereas snowmelt and vegetation cover dynamics were key controls in the north-east; seasonal vegetation cover dynamics (phenology and interception were important along the Appalachian mountain range in the east. A simple two-bucket model (with no other additions was found to be adequate in warm humid catchments along the west coast and in the south-east, with both regions exhibiting strong seasonality, whereas much more complex models are needed in the dry south and south-west. Agricultural catchments in the mid-west were found to be difficult to predict with the use of simple lumped models, due to the strong influence of human activities. Overall, these process controls arose from general east-west (seasonality and north-south (aridity, temperature trends in climate (with some exceptions, compounded by complex
Coopersmith, E.; Yaeger, M.; Ye, S.; Cheng, L.; Sivapalan, M.
2012-06-01
Predictions of hydrological responses in ungauged catchments can benefit from a classification scheme that can organize and pool together catchments that exhibit a level of hydrologic similarity, especially similarity in some key variable or signature of interest. Since catchments are complex systems with a level of self-organization arising from co-evolution of climate and landscape properties, including vegetation, there is much to be gained from developing a classification system based on a comparative study of a population of catchments across climatic and landscape gradients. The focus of this paper is on climate seasonality and seasonal runoff regime, as characterized by the ensemble mean of within-year variation of climate and runoff. The work on regime behavior is part of an overall study of the physical controls on regional patterns of Flow Duration Curves (FDCs), motivated by the fact that regime behavior leaves a major imprint upon the shape of FDCs, especially the slope of the FDCs. As an exercise in comparative hydrology, the paper seeks to assess the regime behavior of 428 catchments from the MOPEX database simultaneously, classifying and regionalizing them into homogeneous or hydrologically similar groups. A decision tree is developed on the basis of a metric chosen to characterize similarity of regime behavior, using a variant of the Iterative Dichotomiser (ID3) algorithm to form a classification tree and associated catchment classes. In this way, several classes of catchments are distinguished, in which the connection between the catchments' regime behavior and climate and catchment properties becomes self-evident. Only four similarity indices are entered into the algorithm, all of which are obtained from smoothed daily regime curves of climatic variables and runoff. Results demonstrate that climate seasonality plays the most significant role in the classification of US catchments, with rainfall timing and climatic aridity index playing somewhat
Kim, Nam Won; Shin, Mun-Ju; Lee, Jeong Eun
2016-04-01
The analysis of storm effects on floods is essential step for designing hydraulic structure and flood plain. There are previous studies for analyzing the relationship between the storm patterns and peak flow, flood volume and durations for various sizes of the catchments, but they are not enough to analyze the natural storm effects on flood responses quantitatively. This study suggests a novel method of quantitative analysis using unique factors extracted from the time series of storms and floods to investigate the relationship between natural storms and their corresponding flood responses. We used a distributed rainfall-runoff model of Grid based Rainfall-runoff Model (GRM) to generate the simulated flow and areal rainfall for 50 catchments in Republic of Korea size from 5.6 km2 to 1584.2 km2, which are including overlapped dependent catchments and non-overlapped independent catchments. The parameters of the GRM model were calibrated to get the good model performances of Nash-Sutcliffe efficiency. Then Flood-Intensity-Duration Curve (FIDC) and Rainfall-Intensity-Duration Curve (RIDC) were generated by Flood-Duration-Frequency and Intensity-Duration-Frequency methods respectively using the time series of hydrographs and hyetographs. Time of concentration developed for the Korea catchments was used as a consistent measure to extract the unique factors from the FIDC and RIDC over the different size of catchments. These unique factors for the storms and floods were analyzed against the different size of catchments to investigate the natural storm effects on floods. This method can be easily used to get the intuition of the natural storm effects with various patterns on flood responses. Acknowledgement This research was supported by a grant (11-TI-C06) from Advanced Water Management Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government.
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Mendonca, Julyanne C.G.; Mendes, Mariana E.; Hwang, Suy F.; Lima, Fabiana F. [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Santos, Neide, E-mail: july_cgm@yahoo.com.br [Universidade Federal de Pernambuco (CCB/UFPE), Recife, PE (Brazil). Departamento de Genetica
2014-07-01
The cytogenetic study has the chromosomal alterations as biomarkers in absorbed dose estimation by the body of individuals involved in exposure to ionizing radiation by interpreting a dose response calibration curve. Since the development of the technique to the analysis of data, you can see protocol characteristics, leading the International Atomic Energy Agency indicate that any laboratory with intention to carry out biological dosimetry establish their own calibration curves. The Biological Dosimetry Laboratory of the Centro Regional de Ciencias Nucleares (CRCN-NE/CNEN), Brazil, recently established the calibration curve related to gamma radiation ({sup 60}Co). Thus, this work aimed to start the validation of this calibration curve from samples of three different blood donors which were irradiated with an absorbed known single dose of 1 Gy. Samples were exposed to {sup 60}Co source (Glaucoma 220) located in the Department of Nuclear Energy (DEN/UFPE). After fixation with methanol and acetic acid and 5% Giemsa staining, the frequency of chromosomal alterations (dicentric chromosomes, acentric rings and fragments) were established from reading of 500 metaphases per sample and doses were estimated using Dose Estimate program. The results showed that, using the dose-response curve calibration for dicentrics, the dose absorbed estimated for the three individuals ranged from 0.891 - 1,089Gy, taking into account the range of confidence of 95%. By using the dose-response curve for dicentrics added to rings and for the same interval of confidence the doses ranged from 0,849 - 1,081Gy. Thus, the estimative encompassed known absorbed dose the three individuals in confidence interval of 95%. These preliminary results seems to demonstrate that dicentric dose-response curves and dicentrics plus rings established by CRCN-NE / CNEN are valid for dose estimation in exposed individuals. This validation will continue with samples from different individuals at different doses.
The extinction curves of star-forming regions from z=0.1 to 6.7 using GRB afterglow spectroscopy
Zafar, Tayyaba; Fynbo, Johan P U; Malesani, Daniele; Jakobsson, Pall; Postigo, Antonio de Ugarte
2011-01-01
GRB afterglows are well suited to extinction studies due to their brightness, simple power-law spectra and the occurrence of GRBs in distant star forming galaxies. In this paper we present results from the SED analysis of a sample of 41 GRB afterglows, from X-ray to NIR wavelengths. This is the largest sample of extinction curves outside the Local Group and, to date, the only extragalactic sample of absolute extinction curves based on spectroscopy. Visual extinction correlation with HI column density as well as total and gas-phase metal column density are examined. Approximately half the sample require a cooling break between the optical and X-ray regimes. The broken power-law SEDs show an average change in the spectral index of delta_beta=0.51 with a standard deviation of 0.02. This is consistent with the expectation from a simple synchrotron model. Of the sample, 63% are well described by the SMC-type extinction curve and have moderate or low extinction, with AV1.0. We find an anti-correlation between gas-t...
Curved Gabor Filters for Fingerprint Image Enhancement
Gottschlich, Carsten
2011-01-01
Gabor filters play an important role in many application areas for the enhancement of various types of images and the extraction of Gabor features. For the purpose of enhancing curved structures in noisy images, we introduce curved Gabor filters which locally adapt their shape to the direction of flow. These curved Gabor filters enable the choice of filter parameters which increase the smoothing power without creating artifacts in the enhanced image. In this paper, curved Gabor filters are applied to the curved ridge and valley structure of low-quality fingerprint images. First, we combine two orientation field estimation methods in order to obtain a more robust estimation for very noisy images. Next, curved regions are constructed by following the respective local orientation and they are used for estimating the local ridge frequency. Lastly, curved Gabor filters are defined based on curved regions and they are applied for the enhancement of low-quality fingerprint images. Experimental results on the FVC2004...
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Je Hyun Baekt
2000-01-01
Full Text Available A numerical study is conducted on the fully-developed laminar flow of an incompressible viscous fluid in a square duct rotating about a perpendicular axis to the axial direction of the duct. At the straight duct, the rotation produces vortices due to the Coriolis force. Generally two vortex cells are formed and the axial velocity distribution is distorted by the effect of this Coriolis force. When a convective force is weak, two counter-rotating vortices are shown with a quasi-parabolic axial velocity profile for weak rotation rates. As the rotation rate increases, the axial velocity on the vertical centreline of the duct begins to flatten and the location of vorticity center is moved near to wall by the effect of the Coriolis force. When the convective inertia force is strong, a double-vortex secondary flow appears in the transverse planes of the duct for weak rotation rates but as the speed of rotation increases the secondary flow is shown to split into an asymmetric configuration of four counter-rotating vortices. If the rotation rates are increased further, the secondary flow restabilizes to a slightly asymmetric double-vortex configuration. Also, a numerical study is conducted on the laminar flow of an incompressible viscous fluid in a 90°-bend square duct that rotates about axis parallel to the axial direction of the inlet. At a 90°-bend square duct, the feature of flow by the effect of a Coriolis force and a centrifugal force, namely a secondary flow by the centrifugal force in the curved region and the Coriolis force in the downstream region, is shown since the centrifugal force in curved region and the Coriolis force in downstream region are dominant respectively.
Multiphasic growth curve analysis.
Koops, W.J.
1986-01-01
Application of a multiphasic growth curve is demonstrated with 4 data sets, adopted from literature. The growth curve used is a summation of n logistic growth functions. Human height growth curves of this type are known as "double logistic" (n = 2) and "triple logistic" (n = 3) growth curves (Bock
Natsume, Takahiro; Ishida, Masaki; Kitagawa, Kakuya; Nagata, Motonori; Sakuma, Hajime; Ichihara, Takashi
2015-11-01
The purpose of this study was to develop a method to determine time discrepancies between input and myocardial time-signal intensity (TSI) curves for accurate estimation of myocardial perfusion with first-pass contrast-enhanced MRI. Estimation of myocardial perfusion with contrast-enhanced MRI using kinetic models requires faithful recording of contrast content in the blood and myocardium. Typically, the arterial input function (AIF) is obtained by setting a region of interest in the left ventricular cavity. However, there is a small delay between the AIF and the myocardial curves, and such time discrepancies can lead to errors in flow estimation using Patlak plot analysis. In this study, the time discrepancies between the arterial TSI curve and the myocardial tissue TSI curve were estimated based on the compartment model. In the early phase after the arrival of the contrast agent in the myocardium, the relationship between rate constant K1 and the concentrations of Gd-DTPA contrast agent in the myocardium and arterial blood (LV blood) can be described by the equation K1={dCmyo(tpeak)/dt}/Ca(tpeak), where Cmyo(t) and Ca(t) are the relative concentrations of Gd-DTPA contrast agent in the myocardium and in the LV blood, respectively, and tpeak is the time corresponding to the peak of Ca(t). In the ideal case, the time corresponding to the maximum upslope of Cmyo(t), tmax, is equal to tpeak. In practice, however, there is a small difference in the arrival times of the contrast agent into the LV and into the myocardium. This difference was estimated to correspond to the difference between tpeak and tmax. The magnitudes of such time discrepancies and the effectiveness of the correction for these time discrepancies were measured in 18 subjects who underwent myocardial perfusion MRI under rest and stress conditions. The effects of the time discrepancies could be corrected effectively in the myocardial perfusion estimates.
Paixao, Edson; Mirza, M. Monirul Qader; Shephard, Mark W.; Auld, Heather; Klaassen, Joan; Smith, Graham
2015-09-01
Reliable extreme rainfall information is required for many applications including infrastructure design, management of water resources, and planning for weather-related emergencies in urban and rural areas. In this study, in situ TBRG sub-daily rainfall rate observations have been supplemented with weather radar information to better capture the spatial and temporal variability of heavy rainfall events regionally. Comparison of extreme rainfall events show that the absolute differences between the rain gauge and radar generally increase with increasing rainfall. Better agreement between the two observations is found when comparing the collocated radar and TBRG annual maximum values. The median difference is <18% for the annual maximum rainfall values ⩽50 mm. The median of difference of IDF estimates obtained through the Gumbel distribution for 10-year return period values computed from TBRG and radar are also found to be 4%. The overall results of this analysis demonstrates the potential value of incorporating remotely sensed radar with traditional point source TBRG network observations to provide additional insight on extreme rainfall events regionally, especially in terms of identifying homogeneous regions of extreme rainfall. The radar observations are particularly useful in areas where there is insufficient TBRG station density to statistically capture the extreme rainfall events.
There are four natural curves in the spinal column. The cervical, thoracic, lumbar, and sacral curvature. The curves, along with the intervertebral disks, help to absorb and distribute stresses that occur from everyday activities such as walking or from ...
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Janusz Charatonik
1991-11-01
Full Text Available Results concerning contractibility of curves (equivalently: of dendroids are collected and discussed in the paper. Interrelations tetween various conditions which are either sufficient or necessary for a curve to be contractible are studied.
Parametrizing Algebraic Curves
Lemmermeyer, Franz
2011-01-01
We present the technique of parametrization of plane algebraic curves from a number theorist's point of view and present Kapferer's simple and beautiful (but little known) proof that nonsingular curves of degree > 2 cannot be parametrized by rational functions.
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Z. J. Zuo
2013-12-01
Full Text Available Magnetoelectric (ME coefficient dependence on the bias magnetic field at resonance frequencies for the bi-layered bonded Terfenol-D/Pb(Zr,TiO3 composite was investigated. The resonance frequency decreases first and then increases with the bias magnetic field (HDC, showing a “V” shape in the range of 0 ∼ 5 kOe. Below the resonance frequency, the pattern of ME coefficient dependence on the HDC shows a single peak, but splits into a double-peak pattern when the testing frequency increases into a certain region. With increasing the frequency, a divergent evolution of the HDC patterns was observed. Domain motion and ΔE effect combined with magnetostriction-piezoelectric coupling effect were employed to explain this experimental result.
Downscaling of Short-Term Precipitation from Regional Climate Models for Sustainable Urban Planning
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Holger Hoppe
2012-05-01
Full Text Available A framework for downscaling precipitation from RCM projections to the high resolutions in time and space required in the urban hydrological climate change impact assessment is outlined and demonstrated. The basic approach is that of Delta Change, developed for both continuous and event-based applications. In both cases, Delta Change Factors (DCFs are calculated which represent the expected future change of some key precipitation statistics. In the continuous case, short-term precipitation from climate projections are analysed in order to estimate DCFs associated with different percentiles in the frequency distribution of non-zero intensities. The DCFs may then be applied to an observed time series, producing a realisation of a future time series. The event-based case involves downscaling of Intensity-Duration-Frequency (IDF curves based on extreme value analysis of annual maxima using the Gumbel distribution. The resulting DCFs are expressed as a function of duration and frequency (i.e., return period and may be used to estimate future design storms. The applications are demonstrated in case studies focusing on the expected changes in short-term precipitation statistics until 2100 in the cities of Linz (Austria and Wuppertal (Germany. The downscaling framework is implemented in the climate service developed within the EU-project SUDPLAN.
Institute of Scientific and Technical Information of China (English)
王亮; 王敏杰; 魏兆成; 王升福
2012-01-01
针对球头铣刀三维曲面加工,提出一种刀具切触区域仿真的通用解析模型.采用微分方法,将曲面加工过程离散为一系列连续的微小斜平面稳态加工.以每一小斜面切削过程为研究对象,建立描述刀具进给方向变化的数学模型,针对不同的进给方向并基于空间坐标系旋转变换,提出一组确定刀具切触边界曲线及各边界交点的解析公式,以精确界定刀具切触区域的封闭几何.通过与Z-Map模型的切触区域仿真对比,验证了本文模型的有效性及其精确高效的特点.%This paper presents a generalized analytical model of cutter engagement region simulations for ball - end milling of 3D curved surface. With differential method, the curved surface machining is treated as a series of sequential small inclined surfaces steady state milling. According to the cutting process of each small inclined surface, the mathematical models which are used to describe the variation of cutter feed direction are established. Through space coordinate system rotation transformation, a set of analytic formula of cutter contact boundaries and the intersection points are proposed, in order to exactly determine the closed geometry of engagement regions for different feed directions. The effectiveness and characteristics of accuracy and high - efficiency of the model presented in this paper are verified by the comparison of engagement region simulations with Z - Map model.
DEFF Research Database (Denmark)
Bernstein, Daniel J.; Birkner, Peter; Lange, Tanja;
2013-01-01
This paper introduces EECM-MPFQ, a fast implementation of the elliptic-curve method of factoring integers. EECM-MPFQ uses fewer modular multiplications than the well-known GMP-ECM software, takes less time than GMP-ECM, and finds more primes than GMP-ECM. The main improvements above the modular......-arithmetic level are as follows: (1) use Edwards curves instead of Montgomery curves; (2) use extended Edwards coordinates; (3) use signed-sliding-window addition-subtraction chains; (4) batch primes to increase the window size; (5) choose curves with small parameters and base points; (6) choose curves with large...
Nakanishi, Hiroyuki; Kurayama, Tomoharu; Matsuo, Mitsuhiro; Imai, Hiroshi; Burns, Ross A; Ozawa, Takeaki; Honma, Mareki; Shibata, Katsunori; Kawaguchi, Noriyuki
2015-01-01
We conducted astrometric VLBI observations of water-vapor maser emission in the massive star forming region IRAS 21379+5106 to measure the annual parallax and proper motion, using VERA. The annual parallax was measured to be $0.262 \\pm 0.031$ mas corresponding to a trigonometric distance of $3.82^{+0.51}_{-0.41}$ kpc. The proper motion was $(\\mu_\\alpha\\cos{\\delta}, \\mu_\\delta)=(-2.74 \\pm 0.08, -2.87 \\pm 0.18)$ mas yr$^{-1}$. Using this result, the Galactic rotational velocity was estimated to be $V_\\theta=218\\pm 19$ km s$^{-1}$ at the Galactocentric distance $R=9.22\\pm0.43$ kpc, when we adopted the Galactic constants $R_0=8.05\\pm 0.45$ kpc and $V_0=238\\pm 14$ km s$^{-1}$. With newly determined distance, {the bolometric luminosity of the central young stellar object was re-evaluated to $(2.15\\pm 0.54)\\times 10^3 L_\\odot$, which corresponds to spectral type of} B2--B3. Maser features were found to be distributed along a straight line from south-west to north-east. In addition, a vector map of the internal motio...
N(o)ther-type theorem of piecewise algebraic curves
Institute of Scientific and Technical Information of China (English)
WANG Renhong; ZHU Chungang
2004-01-01
The piecewise algebraic curve is a generalization of the classical algebraic curve.This paper describes the improvement of the Nother-type theorem of piecewise algebraic curves on the star region.Moreover,the Nother-type theorem of piecewise algebraic curves on the cross-cut partition is discussed.
Herath, H. M. S. M.; Sarukkalige, P. R.; Nguyen, V. T. V.
2015-06-01
Downscaling of climate projections is the most adopted method to assess the impacts of climate change at regional and local scale. In the last decade, downscaling techniques which provide reasonable improvement to resolution of General Circulation Models' (GCMs) output are developed in notable manner. Most of these techniques are limited to spatial downscaling of GCMs' output and still there is a high demand to develop temporal downscaling approaches. As the main objective of this study, combined approach of spatial and temporal downscaling is developed to improve the resolution of rainfall predicted by GCMs. Canberra airport region is subjected to this study and the applicability of proposed downscaling approach is evaluated for Sydney, Melbourne, Brisbane, Adelaide, Perth and Darwin regions. Statistical Downscaling Model (SDSM) is used to spatial downscaling and numerical model based on scaling invariant concept is used to temporal downscaling of rainfalls. National Centre of Environmental Prediction (NCEP) data is used in SDSM model calibration and validation. Regression based bias correction function is used to improve the accuracy of downscaled annual maximum rainfalls using HadCM3-A2. By analysing the non-central moments of observed rainfalls, single time regime (from 30 min to 24 h) is identified which exist scaling behaviour and it is used to estimate the sub daily extreme rainfall depths from daily downscaled rainfalls. Finally, as the major output of this study, Intensity Duration Frequency (IDF) relations are developed for the future periods of 2020s, 2050s and 2080s in the context of climate change.
Coppens, Marc
2011-01-01
We consider coverings of real algebraic curves to real rational algebraic curves. We show the existence of such coverings having prescribed topological degree on the real locus. From those existence results we prove some results on Brill-Noether Theory for pencils on real curves. For coverings having topological degree 0 we introduce the covering number k and we prove the existence of coverings of degree 4 with prescribed covering number.
Directory of Open Access Journals (Sweden)
René Pellissier
2012-01-01
Full Text Available This paper explores the notion ofjump ing the curve,following from Handy 's S-curve onto a new curve with new rules policies and procedures. . It claims that the curve does not generally lie in wait but has to be invented by leadership. The focus of this paper is the identification (mathematically and inferentially ofthat point in time, known as the cusp in catastrophe theory, when it is time to change - pro-actively, pre-actively or reactively. These three scenarios are addressed separately and discussed in terms ofthe relevance ofeach.
Using Dragon Curves To Learn about Length and Area.
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)
Simulating Supernova Light Curves
Energy Technology Data Exchange (ETDEWEB)
Even, Wesley Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dolence, Joshua C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-05-05
This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth’s atmosphere.
Tempo curves considered harmful
Desain, P.; Honing, H.
1993-01-01
In the literature of musicology, computer music research and the psychology of music, timing or tempo measurements are mostly presented in the form of continuous curves. The notion of these tempo curves is dangerous, despite its widespread use, because it lulls its users into the false impression th
Pairings on hyperelliptic curves
Balakrishnan, Jennifer; Chisholm, Sarah; Eisentraeger, Kirsten; Stange, Katherine; Teske, Edlyn
2009-01-01
We assemble and reorganize the recent work in the area of hyperelliptic pairings: We survey the research on constructing hyperelliptic curves suitable for pairing-based cryptography. We also showcase the hyperelliptic pairings proposed to date, and develop a unifying framework. We discuss the techniques used to optimize the pairing computation on hyperelliptic curves, and present many directions for further research.
National Research Council Canada - National Science Library
Andreas Chai; Alessio Moneta
2010-01-01
..., Professor of Economics, University of Illinois, Chicago, at jpersky@uic.edu jpersky@uic.edu.. Introduction Introduction Engel curves describe how household expenditure on particular goods or Engel curves describe how household expenditure on particular goods or services depends on household income. The name comes from the German st...
Martínez, Sol Sáez; de la Rosa, Félix Martínez; Rojas, Sergio
2017-01-01
In Advanced Calculus, our students wonder if it is possible to graphically represent a tornado by means of a three-dimensional curve. In this paper, we show it is possible by providing the parametric equations of such tornado-shaped curves.
Chou, Kai-Seng
2001-01-01
Although research in curve shortening flow has been very active for nearly 20 years, the results of those efforts have remained scattered throughout the literature. For the first time, The Curve Shortening Problem collects and illuminates those results in a comprehensive, rigorous, and self-contained account of the fundamental results.The authors present a complete treatment of the Gage-Hamilton theorem, a clear, detailed exposition of Grayson''s convexity theorem, a systematic discussion of invariant solutions, applications to the existence of simple closed geodesics on a surface, and a new, almost convexity theorem for the generalized curve shortening problem.Many questions regarding curve shortening remain outstanding. With its careful exposition and complete guide to the literature, The Curve Shortening Problem provides not only an outstanding starting point for graduate students and new investigations, but a superb reference that presents intriguing new results for those already active in the field.
Directory of Open Access Journals (Sweden)
Paulo Prochno
2004-07-01
Full Text Available Learning curves have been studied for a long time. These studies provided strong support to the hypothesis that, as organizations produce more of a product, unit costs of production decrease at a decreasing rate (see Argote, 1999 for a comprehensive review of learning curve studies. But the organizational mechanisms that lead to these results are still underexplored. We know some drivers of learning curves (ADLER; CLARK, 1991; LAPRE et al., 2000, but we still lack a more detailed view of the organizational processes behind those curves. Through an ethnographic study, I bring a comprehensive account of the first year of operations of a new automotive plant, describing what was taking place on in the assembly area during the most relevant shifts of the learning curve. The emphasis is then on how learning occurs in that setting. My analysis suggests that the overall learning curve is in fact the result of an integration process that puts together several individual ongoing learning curves in different areas throughout the organization. In the end, I propose a model to understand the evolution of these learning processes and their supporting organizational mechanisms.
Halwatura, D.; Lechner, A. M.; Arnold, S.
2015-02-01
Eastern Australia has considerable mineral and energy resources, with areas of high biodiversity value co-occurring over a broad range of agro-climatic environments. Lack of water is the primary abiotic stressor for (agro)ecosystems in many parts of eastern Australia. In the context of mined land rehabilitation quantifying the severity-duration-frequency (SDF) of droughts is crucial for successful ecosystem rehabilitation to overcome challenges of early vegetation establishment and long-term ecosystem resilience. The objective of this study was to quantify the SDF of short-term and long-term drought events of 11 selected locations across a broad range of agro-climatic environments in eastern Australia by using three drought indices at different timescales: the Standardized Precipitation Index (SPI), the Reconnaissance Drought Index (RDI), and the Standardized Precipitation-Evapotranspiration Index (SPEI). Based on the indices we derived bivariate distribution functions of drought severity and duration, and estimated the recurrence intervals of drought events at different timescales. The correlation between the simple SPI and the more complex SPEI or RDI was stronger for the tropical and temperate locations than for the arid locations, indicating that SPEI or RDI can be replaced by SPI if evaporation plays a minor role for plant available water (tropics). Both short-term and long-term droughts were most severe and prolonged, and recurred most frequently in arid regions, but were relatively rare in tropical and temperate regions. Our approach is similar to intensity-duration-frequency (IDF) analyses of rainfall, which are crucial for the design of hydraulic infrastructure. In this regard, we propose to apply SDF analyses of droughts to design ecosystem components in post-mining landscapes. Together with design rainfalls, design droughts should be used to assess rehabilitation strategies and ecological management using drought recurrence intervals, thereby minimising
Optical conductivity of curved graphene.
Chaves, A J; Frederico, T; Oliveira, O; de Paula, W; Santos, M C
2014-05-07
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.
U.S. Environmental Protection Agency — an UV calibration curve for SRHA quantitation. This dataset is associated with the following publication: Chang, X., and D. Bouchard. Surfactant-Wrapped Multiwalled...
Directory of Open Access Journals (Sweden)
Sutawanir Darwis
2012-05-01
Full Text Available Empirical decline curve analysis of oil production data gives reasonable answer in hyperbolic type curves situations; however the methodology has limitations in fitting real historical production data in present of unusual observations due to the effect of the treatment to the well in order to increase production capacity. The development ofrobust least squares offers new possibilities in better fitting production data using declinecurve analysis by down weighting the unusual observations. This paper proposes a robustleast squares fitting lmRobMM approach to estimate the decline rate of daily production data and compares the results with reservoir simulation results. For case study, we usethe oil production data at TBA Field West Java. The results demonstrated that theapproach is suitable for decline curve fitting and offers a new insight in decline curve analysis in the present of unusual observations.
Large Curved Surface Measurement
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The measurement principle of large curved surface through theodolite industry survey system is introduced. Two methods are suggested with respect to the distribution range of curved surface error. The experiments show that the measurement precision can be up to 0.15mm with relative precision of 3×10-5. Finally, something needed paying attention to and the application aspects on theodolite industry survey system are given.
2015-01-01
In this paper we consider an elementary, and largely unexplored, combinatorial problem in low-dimensional topology. Consider a real 2-dimensional compact surface $S$, and fix a number of points $F$ on its boundary. We ask: how many configurations of disjoint arcs are there on $S$ whose boundary is $F$? We find that this enumerative problem, counting curves on surfaces, has a rich structure. For instance, we show that the curve counts obey an effective recursion, in the general framework of to...
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
This is the note for a series of lectures that the author gave at the Centre de Recerca Matemtica (CRM), Bellaterra, Barcelona, Spain on October 19–24, 2009. The aim is to give a comprehensive description of some recent work of the author and his students on generalisations of the Gross-Zagier formula, Euler systems on Shimura curves, and rational points on elliptic curves.
Highly curved microchannel plates
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.
Relation among C-curve characterization diagrams
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
As three control points are fixed and the fourth control point varies, the planar cubic C-curve may take on a loop, a cusp, or zero to two inflection points, depending on the position of the moving point. The plane can, therefore, be partitioned into regions labelled according to the characterization of the curve when the fourth point is in each region. This partitioned plane is called a "characterization diagram". By moving one of the control points but fixing the rest, one can induce different characterization diagrams. In this paper, we investigate the relation among all different characterization diagrams of cubic C-curves based on the singularity conditions proposed by Yang and Wang (2004). We conclude that, no matter what the C-curve type is or which control point varies, the characterization diagrams can be obtained by cutting a common 3D characterization space with a corresponding plane.
Approximation by planar elastic curves
DEFF Research Database (Denmark)
Brander, David; Gravesen, Jens; Nørbjerg, Toke Bjerge
2016-01-01
We give an algorithm for approximating a given plane curve segment by a planar elastic curve. The method depends on an analytic representation of the space of elastic curve segments, together with a geometric method for obtaining a good initial guess for the approximating curve. A gradient......-driven optimization is then used to find the approximating elastic curve....
Directory of Open Access Journals (Sweden)
Chunping Tan
2015-09-01
Full Text Available The Ningxia Hui Autonomous Region of China (Ningxia is an important food production area in northwest China severely affected by drought. The Standardized Precipitation Index (SPI and Standardized Precipitation Evapotranspiration Index (SPEI were calculated based on monthly meteorological data to explore climate change and variation in drought intensity, duration, frequency, and spatial extent in Ningxia during 1972–2011. Results show that the SPEI is more applicable than the SPI for exploring climate change and drought variation in Ningxia. The Ningxia climate experienced a significant drying tendency. Annual SPEI decreased about 0.37 decade−1 during 1972–2011. Drought was exacerbated by this drying tendency. Regional average duration, maximum duration, intensity, and frequency of drought identified by the SPEI increased by one month, three months, 0.15%, and 36.1%, respectively, during 1992–2011 compared to the period of 1972–1991. The spatial extent of drought identified by the SPEI increased about 14.4% decade−1 in the spring during 1972–2011. Spatially, drought frequency increased from north to south. Average intensity (maximum duration of drought calculated by the SPEI increased (decreased northward and southward from the central arid area.
Stankova-Frenkel, Z E
1997-01-01
We study the moduli of trigonal curves. We establish the exact upper bound of ${36(g+1)}/(5g+1)$ for the slope of trigonal fibrations. Here, the slope of any fibration $X\\to B$ of stable curves with smooth general member is the ratio Hodge class $\\lambda$ on the moduli space $\\bar{\\mathfrak{M}}_g$ to the base $B$. We associate to a trigonal family $X$ a canonical rank two vector bundle $V$, and show that for Bogomolov-semistable $V$ the slope satisfies the stronger inequality ${\\delta_B}/{\\lambda_B}\\leq 7+{6}/{g}$. We further describe the rational Picard group of the {trigonal} locus $\\bar{\\mathfrak T}_g$ in the moduli space $\\bar{\\mathfrak{M}}_g$ of genus $g$ curves. In the even genus case, we interpret the above Bogomolov semistability condition in terms of the so-called Maroni divisor in $\\bar{\\mathfrak T}_g$.
DEFF Research Database (Denmark)
Gómez Arranz, Paula; Vesth, Allan
This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here, the refere......This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here......, the reference wind speed used in the power curve is the equivalent wind speed obtained from lidar measurements at several heights between lower and upper blade tip, in combination with a hub height meteorological mast. The measurements have been performed using DTU’s measurement equipment, the analysis...
Leslie, Mark; Holloway, Charles A
2006-01-01
When a company launches a new product into a new market, the temptation is to immediately ramp up sales force capacity to gain customers as quickly as possible. But hiring a full sales force too early just causes the firm to burn through cash and fail to meet revenue expectations. Before it can sell an innovative product efficiently, the entire organization needs to learn how customers will acquire and use it, a process the authors call the sales learning curve. The concept of a learning curve is well understood in manufacturing. Employees transfer knowledge and experience back and forth between the production line and purchasing, manufacturing, engineering, planning, and operations. The sales learning curve unfolds similarly through the give-and-take between the company--marketing, sales, product support, and product development--and its customers. As customers adopt the product, the firm modifies both the offering and the processes associated with making and selling it. Progress along the manufacturing curve is measured by tracking cost per unit: The more a firm learns about the manufacturing process, the more efficient it becomes, and the lower the unit cost goes. Progress along the sales learning curve is measured in an analogous way: The more a company learns about the sales process, the more efficient it becomes at selling, and the higher the sales yield. As the sales yield increases, the sales learning process unfolds in three distinct phases--initiation, transition, and execution. Each phase requires a different size--and kind--of sales force and represents a different stage in a company's production, marketing, and sales strategies. Adjusting those strategies as the firm progresses along the sales learning curve allows managers to plan resource allocation more accurately, set appropriate expectations, avoid disastrous cash shortfalls, and reduce both the time and money required to turn a profit.
Algebraic curves and cryptography
Murty, V Kumar
2010-01-01
It is by now a well-known paradigm that public-key cryptosystems can be built using finite Abelian groups and that algebraic geometry provides a supply of such groups through Abelian varieties over finite fields. Of special interest are the Abelian varieties that are Jacobians of algebraic curves. All of the articles in this volume are centered on the theme of point counting and explicit arithmetic on the Jacobians of curves over finite fields. The topics covered include Schoof's \\ell-adic point counting algorithm, the p-adic algorithms of Kedlaya and Denef-Vercauteren, explicit arithmetic on
DEFF Research Database (Denmark)
Gómez Arranz, Paula; Villanueva, Héctor
This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here......, the reference wind speed used in the power curve is the equivalent wind speed obtained from lidar measurements at several heights between lower and upper blade tip, in combination with a hub height meteorological mast. The measurements have been performed using DTU’s measurement equipment, the analysis...
DEFF Research Database (Denmark)
Villanueva, Héctor; Vesth, Allan
are not performed according to IEC 61400-12-1 [1]. Therefore, the results presented in this report cannot be considered a power curve according to the reference standard, and are referred to as “power curve investigation” instead. The measurements have been performed by a customer and the data analysis has been......This report describes the analysis carried out with data from a given turbine in a wind farm and a chosen period. The purpose of the analysis is to correlate the power output of the wind turbine to the wind speed measured by a nacelle-mounted anemometer. The measurements and analysis...
Paths of algebraic hyperbolic curves
Institute of Scientific and Technical Information of China (English)
Ya-juan LI; Li-zheng LU; Guo-zhao WANG
2008-01-01
Cubic algebraic hyperbolic (AH) Bezier curves and AH spline curves are defined with a positive parameter α in the space spanned by {1, t, sinht, cosht}. Modifying the value of α yields a family of AH Bezier or spline curves with the family parameter α. For a fixed point on the original curve, it will move on a defined curve called "path of AH curve" (AH Bezier and AH spline curves) when α changes. We describe the geometric effects of the paths and give a method to specify a curve passing through a given point.
DEFF Research Database (Denmark)
Gómez Arranz, Paula; Wagner, Rozenn
This report describes the power curve measurements performed with a nacelle LIDAR on a given wind turbine in a wind farm and during a chosen measurement period. The measurements and analysis are carried out in accordance to the guidelines in the procedure “DTU Wind Energy-E-0019” [1]. The reporting...
Kool, J.
2013-01-01
This thesis has three main subjects. The first subject is Measure-theoretic rigidity of Mumford Curves. One can describe isomorphism of two compact hyperbolic Riemann surfaces of the same genus by a measure-theoretic property: a chosen isomorphism of their fundamental groups corresponds to a homeomo
DEFF Research Database (Denmark)
Vesth, Allan; Kock, Carsten Weber
The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present anal...
DEFF Research Database (Denmark)
Villanueva, Héctor; Gómez Arranz, Paula
The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...
DEFF Research Database (Denmark)
Gómez Arranz, Paula; Villanueva, Héctor
The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...
Ph.H.B.F. Franses (Philip Hans)
1994-01-01
textabstractIn this paper, a simple Gompertz curve-fitting procedure is proposed. Its advantages include the facts that the stability of the saturation level over the sample period can be checked, and that no knowledge of its value is necessary for forecasting. An application to forecasting the stoc
Gompertz curves with seasonality
Ph.H.B.F. Franses (Philip Hans)
1994-01-01
textabstractThis paper considers an extension of the usual Gompertz curve by allowing the parameters to vary over the seasons. This means that, for example, saturation levels can be different over the year. An estimation and testing method is proposed and illustrated with an example.
DEFF Research Database (Denmark)
Gómez Arranz, Paula; Vesth, Allan
The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...
DEFF Research Database (Denmark)
Vesth, Allan; Yordanova, Ginka
The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...
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…
Power Curve Measurements, REWS
DEFF Research Database (Denmark)
Villanueva, Héctor; Gómez Arranz, Paula
This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here, the refere...
DEFF Research Database (Denmark)
Federici, Paolo; Kock, Carsten Weber
This report describes the power curve measurements performed with a nacelle LIDAR on a given wind turbine in a wind farm and during a chosen measurement period. The measurements and analysis are carried out in accordance to the guidelines in the procedure “DTU Wind Energy-E-0019” [1]. The reporting...
Straightening Out Learning Curves
Corlett, E. N.; Morecombe, V. J.
1970-01-01
The basic mathematical theory behind learning curves is explained, together with implications for clerical and industrial training, evaluation of skill development, and prediction of future performance. Brief studies of textile worker and typist training are presented to illustrate such concepts as the reduction fraction (a consistent decrease in…
Groot, L.F.M.
The purpose of this paper is twofold. First, it exhibits that standard tools in the measurement of income inequality, such as the Lorenz curve and the Gini-index, can successfully be applied to the issues of inequality measurement of carbon emissions and the equity of abatement policies across
DEFF Research Database (Denmark)
Kock, Carsten Weber; Federici, Paolo
The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...... analyze of power performance of the turbine....
DEFF Research Database (Denmark)
Kock, Carsten Weber; Vesth, Allan
The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...... analyze of power performance of the turbine....
Energy Technology Data Exchange (ETDEWEB)
Groot, L. [Utrecht University, Utrecht School of Economics, Janskerkhof 12, 3512 BL Utrecht (Netherlands)
2008-11-15
The purpose of this paper is twofold. First, it exhibits that standard tools in the measurement of income inequality, such as the Lorenz curve and the Gini-index, can successfully be applied to the issues of inequality measurement of carbon emissions and the equity of abatement policies across countries. These tools allow policy-makers and the general public to grasp at a single glance the impact of conventional distribution rules such as equal caps or grandfathering, or more sophisticated ones, on the distribution of greenhouse gas emissions. Second, using the Samuelson rule for the optimal provision of a public good, the Pareto-optimal distribution of carbon emissions is compared with the distribution that follows if countries follow Nash-Cournot abatement strategies. It is shown that the Pareto-optimal distribution under the Samuelson rule can be approximated by the equal cap division, represented by the diagonal in the Lorenz curve diagram.
Directory of Open Access Journals (Sweden)
Iram Ansari
2012-01-01
Full Text Available Dilaceration is the result of a developmental anomaly in which there has been an abrupt change in the axial inclination between the crown and the root of a tooth. Dilaceration can be seen in both the permanent and deciduous dentitions, and is more commonly found in posterior teeth and in maxilla. Periapical radiographs are the most appropriate way to diagnose the presence of root dilacerations. The controlled regularly tapered preparation of the curved canals is the ultimate challenge in endodontics. Careful and meticulous technique will yield a safe and sufficient enlargement of the curved canals. This article gives a review of the literature and three interesting case reports of root dilacerations.
Vo, Martin
2017-08-01
Light Curves Classifier uses data mining and machine learning to obtain and classify desired objects. This task can be accomplished by attributes of light curves or any time series, including shapes, histograms, or variograms, or by other available information about the inspected objects, such as color indices, temperatures, and abundances. After specifying features which describe the objects to be searched, the software trains on a given training sample, and can then be used for unsupervised clustering for visualizing the natural separation of the sample. The package can be also used for automatic tuning parameters of used methods (for example, number of hidden neurons or binning ratio). Trained classifiers can be used for filtering outputs from astronomical databases or data stored locally. The Light Curve Classifier can also be used for simple downloading of light curves and all available information of queried stars. It natively can connect to OgleII, OgleIII, ASAS, CoRoT, Kepler, Catalina and MACHO, and new connectors or descriptors can be implemented. In addition to direct usage of the package and command line UI, the program can be used through a web interface. Users can create jobs for ”training” methods on given objects, querying databases and filtering outputs by trained filters. Preimplemented descriptors, classifier and connectors can be picked by simple clicks and their parameters can be tuned by giving ranges of these values. All combinations are then calculated and the best one is used for creating the filter. Natural separation of the data can be visualized by unsupervised clustering.
Pelce, Pierre
1989-01-01
In recent years, much progress has been made in the understanding of interface dynamics of various systems: hydrodynamics, crystal growth, chemical reactions, and combustion. Dynamics of Curved Fronts is an important contribution to this field and will be an indispensable reference work for researchers and graduate students in physics, applied mathematics, and chemical engineering. The book consist of a 100 page introduction by the editor and 33 seminal articles from various disciplines.
Estimating Corporate Yield Curves
Antionio Diaz; Frank Skinner
2001-01-01
This paper represents the first study of retail deposit spreads of UK financial institutions using stochastic interest rate modelling and the market comparable approach. By replicating quoted fixed deposit rates using the Black Derman and Toy (1990) stochastic interest rate model, we find that the spread between fixed and variable rates of interest can be modeled (and priced) using an interest rate swap analogy. We also find that we can estimate an individual bank deposit yield curve as a spr...
Steenwyk, Steven D; Molnar, Lawrence A
2013-01-01
We have identified some two-hundred new variable stars in a systematic study of a data archive obtained with the Calvin-Rehoboth observatory. Of these, we present five close binaries showing behaviors presumably due to star spots or other magnetic activity. For context, we first present two new RS CVn systems whose behavior can be readily attribute to star spots. Then we present three new close binary systems that are rather atypical, with light curves that are changing over time in ways not easily understood in terms of star spot activity generally associated with magnetically active binary systems called RS CVn systems. Two of these three are contact binaries that exhibit gradual changes in average brightness without noticeable changes in light curve shape. A third system has shown such large changes in light curve morphology that we speculate this may be a rare instance of a system that transitions back and forth between contact and noncontact configurations, perhaps driven by magnetic cycles in at least o...
Curved PVDF airborne transducer.
Wang, H; Toda, M
1999-01-01
In the application of airborne ultrasonic ranging measurement, a partially cylindrical (curved) PVDF transducer can effectively couple ultrasound into the air and generate strong sound pressure. Because of its geometrical features, the ultrasound beam angles of a curved PVDF transducer can be unsymmetrical (i.e., broad horizontally and narrow vertically). This feature is desired in some applications. In this work, a curved PVDF air transducer is investigated both theoretically and experimentally. Two resonances were observed in this transducer. They are length extensional mode and flexural bending mode. Surface vibration profiles of these two modes were measured by a laser vibrometer. It was found from the experiment that the surface vibration was not uniform along the curvature direction for both vibration modes. Theoretical calculations based on a model developed in this work confirmed the experimental results. Two displacement peaks were found in the piezoelectric active direction of PVDF film for the length extensional mode; three peaks were found for the flexural bending mode. The observed peak positions were in good agreement with the calculation results. Transient surface displacement measurements revealed that vibration peaks were in phase for the length extensional mode and out of phase for the flexural bending mode. Therefore, the length extensional mode can generate a stronger ultrasound wave than the flexural bending mode. The resonance frequencies and vibration amplitudes of the two modes strongly depend on the structure parameters as well as the material properties. For the transducer design, the theoretical model developed in this work can be used to optimize the ultrasound performance.
Magnetism in curved geometries
Streubel, Robert; Fischer, Peter; Kronast, Florian; Kravchuk, Volodymyr P.; Sheka, Denis D.; Gaididei, Yuri; Schmidt, Oliver G.; Makarov, Denys
2016-09-01
Extending planar two-dimensional structures into the three-dimensional space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics and magnetics. This approach provides means to modify conventional or to launch novel functionalities by tailoring the geometry of an object, e.g. its local curvature. In a generic electronic system, curvature results in the appearance of scalar and vector geometric potentials inducing anisotropic and chiral effects. In the specific case of magnetism, even in the simplest case of a curved anisotropic Heisenberg magnet, the curvilinear geometry manifests two exchange-driven interactions, namely effective anisotropy and antisymmetric exchange, i.e. Dzyaloshinskii-Moriya-like interaction. As a consequence, a family of novel curvature-driven effects emerges, which includes magnetochiral effects and topologically induced magnetization patterning, resulting in theoretically predicted unlimited domain wall velocities, chirality symmetry breaking and Cherenkov-like effects for magnons. The broad range of altered physical properties makes these curved architectures appealing in view of fundamental research on e.g. skyrmionic systems, magnonic crystals or exotic spin configurations. In addition to these rich physics, the application potential of three-dimensionally shaped objects is currently being explored as magnetic field sensorics for magnetofluidic applications, spin-wave filters, advanced magneto-encephalography devices for diagnosis of epilepsy or for energy-efficient racetrack memory devices. These recent developments ranging from theoretical predictions over fabrication of three-dimensionally curved magnetic thin films, hollow cylinders or wires, to their characterization using integral means as well as the development of advanced tomography approaches are in the focus of this review.
A Probabilistic Framework for Curve Evolution
DEFF Research Database (Denmark)
Dahl, Vedrana Andersen
2017-01-01
approach include ability to handle textured images, simple generalization to multiple regions, and efficiency in computation. We test our probabilistic framework in combination with parametric (snakes) and geometric (level-sets) curves. The experimental results on composed and natural images demonstrate...
Superfluids in Curved Spacetime
Villegas, Kristian Hauser A
2015-01-01
Superfluids under an intense gravitational field are typically found in neutron star and quark star cores. Most treatments of these superfluids, however, are done in a flat spacetime background. In this paper, the effect of spacetime curvature on superfluidity is investigated. An effective four-fermion interaction is derived by integrating out the mediating scalar field. The fermions interacting via the mediating gauge vector bosons is also discussed. Two possible cases are considered in the mean-field treatment: antifermion-fermion and fermion-fermion pairings. An effective action, quadratic in fermion field, and a self-consistent equation are derived for both cases. The effective Euclidean action and the matrix elements of the heat kernel operator, which are very useful in curved-spacetime QFT calculations, are derived for the fermion-fermion pairing. Finally, explicit numerical calculation of the gravitational correction to the pairing order parameter is performed for the scalar superfluid case. It is foun...
Yaman, K; Solis, F J; Witten, T A
1996-01-01
We apply results derived in other contexts for the spectrum of the Laplace operator in curved geometries to the study of an ideal polymer chain confined to a spherical annulus in arbitrary space dimension D and conclude that the free energy compared to its value for an uncurved box of the same thickness and volume, is lower when $D < 3$, stays the same when $D = 3$, and is higher when lowers the effective bending elasticity of the walls, and might induce spontaneous symmetry breaking, i.e. bending. (Actually, the above mentioned results show that {\\em {any}} shell in $D = 3$ induces this effect, except for a spherical shell). We compute the contribution of this effect to the bending rigidities in the Helfrich free energy expression.
Evolutes of Hyperbolic Plane Curves
Institute of Scientific and Technical Information of China (English)
Shyuichi IZUMIYA; Dong He PEI; Takashi SANO; Erika TORII
2004-01-01
We define the notion of evolutes of curves in a hyperbolic plane and establish the relationships between singularities of these subjects and geometric invariants of curves under the action of the Lorentz group. We also describe how we can draw the picture of an evolute of a hyperbolic plane curve in the Poincar(e) disk.
The Arithmetic of Elliptic Curves
Silverman, Joseph H
2009-01-01
Treats the arithmetic theory of elliptic curves in its modern formulation, through the use of basic algebraic number theory and algebraic geometry. This book discusses the necessary algebro-geometric results, and offers an exposition of the geometry of elliptic curves, and the formal group of an elliptic curve.
Johnson, L. E.; Kim, J.; Cifelli, R.; Chandra, C. V.
2016-12-01
Potential water retention, S, is one of parameters commonly used in hydrologic modeling for soil moisture accounting. Physically, S indicates total amount of water which can be stored in soil and is expressed in units of depth. S can be represented as a change of soil moisture content and in this context is commonly used to estimate direct runoff, especially in the Soil Conservation Service (SCS) curve number (CN) method. Generally, the lumped and the distributed hydrologic models can easily use the SCS-CN method to estimate direct runoff. Changes in potential water retention have been used in previous SCS-CN studies; however, these studies have focused on long-term hydrologic simulations where S is allowed to vary at the daily time scale. While useful for hydrologic events that span multiple days, the resolution is too coarse for short-term applications such as flash flood events where S may not recover its full potential. In this study, a new method for estimating a time-variable potential water retention at hourly time-scales is presented. The methodology is applied for the Napa River basin, California. The streamflow gage at St Helena, located in the upper reaches of the basin, is used as the control gage site to evaluate the model performance as it is has minimal influences by reservoirs and diversions. Rainfall events from 2011 to 2012 are used for estimating the event-based SCS CN to transfer to S. As a result, we have derived the potential water retention curve and it is classified into three sections depending on the relative change in S. The first is a negative slope section arising from the difference in the rate of moving water through the soil column, the second is a zero change section representing the initial recovery the potential water retention, and the third is a positive change section representing the full recovery of the potential water retention. Also, we found that the soil water moving has traffic jam within 24 hours after finished first
Study of Families of Curves in the Euclidian Plan
Directory of Open Access Journals (Sweden)
Belaib Lekhmissi
2007-01-01
Full Text Available Non-standard analysis techniques are more considered in approaching complex mathematical domains. By using some concepts of non-standard analysis methods such as regionalization method, we deal with a family of curves in an Euclidian plan. The solutions of the algebraic equations representing these curves in a plan have an hyperbolic forms.
CURVATURE-DEPENDENT PARAMETERIZATION OF CURVES AND SURFACES
KOSTERS, M
1991-01-01
An efficient way of drawing parametric curves and surfaces is to approximate the curve or surface by a sequence of straight-line segments or a mesh of polygons, respectively. In such an approximation, many small line segments or polygons are needed in regions of high curvature, and fewer and larger
Cubic B-spline curve approximation by curve unclamping
Chen, Xiao-Diao; Ma, Weiyin; Paul, Jean-Claude
2010-01-01
International audience; A new approach for cubic B-spline curve approximation is presented. The method produces an approximation cubic B-spline curve tangent to a given curve at a set of selected positions, called tangent points, in a piecewise manner starting from a seed segment. A heuristic method is provided to select the tangent points. The first segment of the approximation cubic B-spline curve can be obtained using an inner point interpolation method, least-squares method or geometric H...
Jeffery, Nathan; Gasser, Robin B; Steer, Penelope A; Noormohammadi, Amir H
2007-08-01
Mycoplasma synoviae is an economically important pathogen of poultry worldwide, causing respiratory infection and synovitis in chickens and turkeys. Identification of M. synoviae isolates is of critical importance, particularly in countries in which poultry flocks are vaccinated with the live attenuated M. synoviae strain MS-H. Using oligonucleotide primers complementary to the single-copy conserved 5' end of the variable lipoprotein and haemagglutinin gene (vlhA), amplicons of approximately 400 bp were generated from 35 different M. synoviae strains/isolates from chickens and subjected to mutation scanning analysis. Analysis of the amplicons by single-strand conformation polymorphism (SSCP) revealed 10 distinct profiles (A-J). Sequencing of the amplicons representing these profiles revealed that each profile related to a unique sequence, some differing from each other by only one base-pair substitution. Comparative high-resolution melting (HRM) curve analysis of the amplicons using SYTO 9 green fluorescent dye also displayed profiles which were concordant with the same 10 SSCP profiles (A-J) and their sequences. For both mutation detection methods, the Australian M. synoviae strains represented one of the A, B, C or D profiles, while the USA strains represented one of the E, F, G, H, I or J profiles. The results presented in this study show that the PCR-based SSCP or HRM curve analyses of vlhA provide high-resolution mutation detection tools for the detection and identification of M. synoviae strains. In particular, the HRM curve analysis is a rapid and effective technique which can be performed in a single test tube in less than 2 h.
Reflection of curved shock waves
Mölder, S.
2017-03-01
Shock curvatures are related to pressure gradients, streamline curvatures and vorticity in flows with planar and axial symmetry. Explicit expressions, in an influence coefficient format, are used to relate post-shock pressure gradient, streamline curvature and vorticity to pre-shock gradients and shock curvature in steady flow. Using higher order, von Neumann-type, compatibility conditions, curved shock theory is applied to calculate the flow near singly and doubly curved shocks on curved surfaces, in regular shock reflection and in Mach reflection. Theoretical curved shock shapes are in good agreement with computational fluid dynamics calculations and experiment.
Reflection of curved shock waves
Mölder, S.
2017-09-01
Shock curvatures are related to pressure gradients, streamline curvatures and vorticity in flows with planar and axial symmetry. Explicit expressions, in an influence coefficient format, are used to relate post-shock pressure gradient, streamline curvature and vorticity to pre-shock gradients and shock curvature in steady flow. Using higher order, von Neumann-type, compatibility conditions, curved shock theory is applied to calculate the flow near singly and doubly curved shocks on curved surfaces, in regular shock reflection and in Mach reflection. Theoretical curved shock shapes are in good agreement with computational fluid dynamics calculations and experiment.
Heegner modules and elliptic curves
Brown, Martin L
2004-01-01
Heegner points on both modular curves and elliptic curves over global fields of any characteristic form the topic of this research monograph. The Heegner module of an elliptic curve is an original concept introduced in this text. The computation of the cohomology of the Heegner module is the main technical result and is applied to prove the Tate conjecture for a class of elliptic surfaces over finite fields; this conjecture is equivalent to the Birch and Swinnerton-Dyer conjecture for the corresponding elliptic curves over global fields.
Closed planar curves without inflections
Ohno, Shuntaro; Umehara, Masaaki
2011-01-01
We define a computable topological invariant $\\mu(\\gamma)$ for generic closed planar regular curves $\\gamma$, which gives an effective lower bound for the number of inflection points on a given generic closed planar curve. Using it, we classify the topological types of locally convex curves (i.e. closed planar regular curves without inflections) whose numbers of crossings are less than or equal to five. Moreover, we discuss the relationship between the number of double tangents and the invariant $\\mu(\\gamma)$ on a given $\\gamma$.
Automating Recession Curve Displacement Recharge Estimation.
Smith, Brennan; Schwartz, Stuart
2017-01-01
Recharge estimation is an important and challenging element of groundwater management and resource sustainability. Many recharge estimation methods have been developed with varying data requirements, applicable to different spatial and temporal scales. The variability and inherent uncertainty in recharge estimation motivates the recommended use of multiple methods to estimate and bound regional recharge estimates. Despite the inherent limitations of using daily gauged streamflow, recession curve displacement methods provide a convenient first-order estimate as part of a multimethod hierarchical approach to estimate watershed-scale annual recharge. The implementation of recession curve displacement recharge estimation in the United States Geologic Survey (USGS) RORA program relies on the subjective, operator-specific selection of baseflow recession events to estimate a gauge-specific recession index. This paper presents a parametric algorithm that objectively automates this tedious, subjective process, parameterizing and automating the implementation of recession curve displacement. Results using the algorithm reproduce regional estimates of groundwater recharge from the USGS Appalachian Valley and Piedmont Regional Aquifer-System Analysis, with an average absolute error of less than 2%. The algorithm facilitates consistent, completely automated estimation of annual recharge that complements more rigorous data-intensive techniques for recharge estimation. © 2016, National Ground Water Association.
DEFF Research Database (Denmark)
Brücker, Herbert; Jahn, Elke J.
Based on a wage curve approach we examine the labor market effects of migration in Germany. The wage curve relies on the assumption that wages respond to a change in the unemployment rate, albeit imperfectly. This allows one to derive the wage and employment effects of migration simultaneously...
NURBS curve blending using extension
Institute of Scientific and Technical Information of China (English)
Yong-jin LIU; Rong-qi QIU; Xiao-hui LIANG
2009-01-01
Curve and surface blending is an important operation in CAD systems, in which a non-uniform rational B-spline (NURBS) has been used as the de facto standard. In local comer blending, two curves intersecting at that comer are first made disjoint, and then the third blending curve is added-in to smoothly join the two curves with G1-or G2-continuity. In this paper we present a study to solve the joint problem based on curve extension. The following nice properties of this extension algorithm are exploited in depth: (1) The parameterization of the original shapes does not change; (2) No additional fragments are created.Various examples are presented to demonstrate that our solution is simple and efficient.
Equations of hyperelliptic Shimura curves
Molina, Santiago
2010-01-01
We describe an algorithm that computes explicit models of hyperelliptic Shimura curves attached to an indefnite quaternion algebra over Q and Atkin-Lehner quotients of them. It exploits Cerednik-Drinfeld's non-archimedean uniformisation of Shimura curves, a formula of Gross and Zagier for the endomorphism ring of Heegner points over Artinian rings and the connection between Ribet's bimodules and the specialization of Heegner points. As an application, we provide a list of equations of Shimura curves and quotients of them obtained by our algorithm that had been conjectured by Kurihara.
Poiseuille flow in curved spaces
Debus, J -D; Succi, S; Herrmann, H J
2015-01-01
We investigate Poiseuille channel flow through intrinsically curved (campylotic) media, equipped with localized metric perturbations (campylons). To this end, we study the flux of a fluid driven through the curved channel in dependence of the spatial deformation, characterized by the campylon parameters (amplitude, range and density). We find that the flux depends only on a specific combination of campylon parameters, which we identify as the average campylon strength, 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.
Hoogwijk, M.M.; Faaij, A.P.C.|info:eu-repo/dai/nl/10685903X; de Vries, B.|info:eu-repo/dai/nl/068361599; Turkenburg, W.C.|info:eu-repo/dai/nl/073416355
2008-01-01
We explored the production cost of energy crops at abandoned agricultural land and at rest land at a regional and a global level to the year 2050 using four different land-use scenarios. The estimations were based on grid cell data on the productivity of short-rotation crops on the available land ov
More Unusual Light Curves from Kepler
Kohler, Susanna
2017-03-01
Twenty-three new objects have been added to the growing collection of stars observed to have unusual dips in their light curves. A recent study examines these stars and the potential causes of their strange behavior.An Influx of DataThe primary Kepler mission provided light curves for over 100,000 stars, and its continuation K2 is observing another 20,000 stars every three months. As we enter an era where these enormous photometric data sets become commonplace Gaia will obtain photometry for millions of stars, and LSST billions its crucial that we understand the different categories of variability observed in these stars.The authors find three different types of light curves among their 23 unusual stars. Scallop-shell curves (top) show many undulations; persistent flux-dip class curves (middle) have discrete triangularly shaped flux dips; transient, narrow dip class curves (bottom) have only one dip that is variable in depth. The authors speculate a common cause for the scallop-shell and persistent flux-dip stars, and a different cause for the transient flux-dip stars. [Stauffer et al. 2017]After filtering out the stars with planets, those in binary systems, those with circumstellar disks, and those with starspots, a number of oddities remain: a menagerie of stars with periodic variability that cant be accounted for in these categories. Some of these stars are now famous (for instance, Boyajians star); some are lesser known. But by continuing to build up this sample of stars with unusual light curves, we have a better chance of understanding the sources of variability.Building the MenagerieTo this end, a team of scientists led by John Stauffer (Spitzer Science Center at Caltech) has recently hunted for more additions to this sample in the K2 data set. In particular, they searched through the light curves from stars in the Oph and Upper Scorpius star-forming region a data set that makes up the largest collection of high-quality light curves for low-mass, pre
Description of dose response curve
Al-Samarai, Firas
2011-01-01
The book included several methods to estimate LD50, in addition to explain how to use several programs to estimate LD50. Moreover the book illustrate the description of the dose response curves. Firas Al-Samarai
Normal origamis of Mumford curves
Kremer, Karsten
2010-01-01
An origami (also known as square-tiled surface) is a Riemann surface covering a torus with at most one branch point. Lifting two generators of the fundamental group of the punctured torus decomposes the surface into finitely many unit squares. By varying the complex structure of the torus one obtains easily accessible examples of Teichm\\"uller curves in the moduli space of Riemann surfaces. The p-adic analogues of Riemann surfaces are Mumford curves. A p-adic origami is defined as a covering of Mumford curves with at most one branch point, where the bottom curve has genus one. A classification of all normal non-trivial p-adic origamis is presented and used to calculate some invariants. These can be used to describe p-adic origamis in terms of glueing squares.
String networks as tropical curves
Ray, Koushik
2008-01-01
A prescription for obtaining supergravity solutions for planar (p,q)-string networks is presented, based on earlier results. It shows that networks may be looked upon as tropical curves emerging as the spine of the amoeba of a holomorphic curve in M-theory. The Kaehler potential of supergravity is identified with the corresponding Ronkin function. Implications of this identification in counting dyons is discussed.
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 co...
Flow over riblet curved surfaces
Energy Technology Data Exchange (ETDEWEB)
Loureiro, J B R; Freire, A P Silva, E-mail: atila@mecanica.ufrj.br [Mechanical Engineering Program, Federal University of Rio de Janeiro (COPPE/UFRJ), C.P. 68503, 21.941-972, Rio de Janeiro, RJ (Brazil)
2011-12-22
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).
Linear Systems on Tropical Curves
Haase, Christian; Yu, Josephine
2009-01-01
A tropical curve \\Gamma is a metric graph with possibly unbounded edges, and tropical rational functions are continuous piecewise linear functions with integer slopes. We define the complete linear system |D| of a divisor D on a tropical curve \\Gamma analogously to the classical counterpart. We investigate the structure of |D| as a cell complex and show that linear systems are quotients of tropical modules, finitely generated by vertices of the cell complex. Using a finite set of generators, |D| defines a map from \\Gamma to a tropical projective space, and the image can be extended to a tropical curve of degree equal to \\deg(D). The tropical convex hull of the image realizes the linear system |D| as a polyhedral complex. We show that curves for which the canonical divisor is not very ample are hyperelliptic. We also show that the Picard group of a \\Q-tropical curve is a direct limit of critical groups of finite graphs converging to the curve.
DEFF Research Database (Denmark)
Albæk, Karsten; Madsen, Erik Strøjer; Asplund, R.
2000-01-01
in the Nordic labor markets once regional fixed effects are accounted for. Wage formation at the regional level is characterized by considerable persistence, but unemployment exerts no immediate influence on wages at the regional level. There is no evidence of a wage curve, nor of a Phillips curve...
Curve Digitizer – A software for multiple curves digitizing
Directory of Open Access Journals (Sweden)
Florentin ŞPERLEA
2010-06-01
Full Text Available The Curve Digitizer is software that extracts data from an image file representing a graphicand returns them as pairs of numbers which can then be used for further analysis and applications.Numbers can be read on a computer screen stored in files or copied on paper. The final result is adata set that can be used with other tools such as MSEXCEL. Curve Digitizer provides a useful toolfor any researcher or engineer interested in quantifying the data displayed graphically. The image filecan be obtained by scanning a document
Reconstructing light curves from HXMT imaging observations
Huo, Zhuo-Xi; Li, Yi-Ming; Zhou, Jian-Feng
2014-01-01
The Hard X-ray Modulation Telescope (HXMT) is a Chinese space telescope mission. It is scheduled for launch in 2015. The telescope will perform an all-sky survey in hard X-ray band (1 - 250 keV), a series of deep imaging observations of small sky regions as well as pointed observations. In this work we present a conceptual method to reconstruct light curves from HXMT imaging observation directly, in order to monitor time-varying objects such as GRB, AXP and SGR in hard X-ray band with HXMT imaging observations.
Dornbos, Peter; Crawford, Robert B; Kaminski, Norbert E; Hession, Sarah L; LaPres, John J
2016-10-01
The influence of interindividual variability is not typically assessed in traditional toxicological studies. Given that chemical exposures occur in heterogeneous populations, this knowledge gap has the potential to cause undue harm within the realms of public health and industrial and municipal finances. A recent report from the National Research Council (NRC) suggests that when accounting for interindividual variation in responses, traditionally assumed nonlinear dose-response relationships (DRRs) for noncancer-causing endpoints would better be explained with a linear relationship within the low-dose region. To address this knowledge gap and directly test the NRC's assumption, this study focused on assessing the DRR between 2,3,7,8-tetracholorodibenzo-p-dioxin (TCDD) exposure and immune suppression in a cohort of unique human donors. Human B cells were isolated from 51 individual donors and treated with logarithmically increasing concentrations of TCDD (0-30 nM TCDD). Two endpoints sensitive to TCDD were assessed: (1) number of IgM-secreting B cells and (2) quantity of IgM secreted. The results show that TCDD significantly suppressed both the number of IgM-secreting B cells and the quantity of IgM secreted (P < .05). Statistical model comparisons indicate that the low-dose region of the two DRRs is best explained with a nonlinear relationship. Rather than assuming low-dose linearity for all noncancer-causing DRRs, our study suggests the need to consider the specific mode of action of toxicants and pharmaceuticals during risk-management decision making. © The Author 2016. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.
Effective nucleon mass and the nuclear caloric curve
Shetty, D V; Galanopoulos, S; Yennello, S J
2009-01-01
Assuming a schematic form of the nucleon effective mass as a function of nuclear excitation energy and mass, we provide a simple explanation for understanding the experimentally observed mass dependence of the nuclear caloric curve. It is observed that the excitation energy at which the caloric curve enters into a plateau region, could be sensitive to the nuclear mass evolution of the effective nucleon mass.
Topological recursion and mirror curves
Bouchard, Vincent
2012-01-01
We study the constant contributions to the free energies obtained through the topological recursion applied to the complex curves mirror to toric Calabi-Yau threefolds. We show that the recursion reproduces precisely the corresponding Gromov-Witten invariants, which can be encoded in powers of the MacMahon function. As a result, we extend the scope of the "remodeling conjecture" to the full free energies, including the constant contributions. In the process we study how the pair of pants decomposition of the mirror curves plays an important role in the topological recursion. We also show that the free energies are not, strictly speaking, symplectic invariants, and that the recursive construction of the free energies does not commute with certain limits of mirror curves.
Laffer Curves and Home Production
Directory of Open Access Journals (Sweden)
Kotamäki Mauri
2017-06-01
Full Text Available In the earlier related literature, consumption tax rate Laffer curve is found to be strictly increasing (see Trabandt and Uhlig (2011. In this paper, a general equilibrium macro model is augmented by introducing a substitute for private consumption in the form of home production. The introduction of home production brings about an additional margin of adjustment – an increase in consumption tax rate not only decreases labor supply and reduces the consumption tax base but also allows a substitution of market goods with home-produced goods. The main objective of this paper is to show that, after the introduction of home production, the consumption tax Laffer curve exhibits an inverse U-shape. Also the income tax Laffer curves are significantly altered. The result shown in this paper casts doubt on some of the earlier results in the literature.
Rational points on elliptic curves
Silverman, Joseph H
2015-01-01
The theory of elliptic curves involves a pleasing blend of algebra, geometry, analysis, and number theory. This book stresses this interplay as it develops the basic theory, thereby providing an opportunity for advanced undergraduates to appreciate the unity of modern mathematics. At the same time, every effort has been made to use only methods and results commonly included in the undergraduate curriculum. This accessibility, the informal writing style, and a wealth of exercises make Rational Points on Elliptic Curves an ideal introduction for students at all levels who are interested in learning about Diophantine equations and arithmetic geometry. Most concretely, an elliptic curve is the set of zeroes of a cubic polynomial in two variables. If the polynomial has rational coefficients, then one can ask for a description of those zeroes whose coordinates are either integers or rational numbers. It is this number theoretic question that is the main subject of this book. Topics covered include the geometry and ...
Canonical curves with low apolarity
Ballico, Edoardo; Notari, Roberto
2010-01-01
Let $k$ be an algebraically closed field and let $C$ be a non--hyperelliptic smooth projective curve of genus $g$ defined over $k$. Since the canonical model of $C$ is arithmetically Gorenstein, Macaulay's theory of inverse systems allows to associate to $C$ a cubic form $f$ in the divided power $k$--algebra $R$ in $g-2$ variables. The apolarity of $C$ is the minimal number $t$ of linear form in $R$ needed to write $f$ as sum of their divided power cubes. It is easy to see that the apolarity of $C$ is at least $g-2$ and P. De Poi and F. Zucconi classified curves with apolarity $g-2$ when $k$ is the complex field. In this paper, we give a complete, characteristic free, classification of curves $C$ with apolarity $g-1$ (and $g-2$).
Szpak, Nikodem
2014-01-01
We present some new ideas on how to design analogue models of quantum fields living in curved spacetimes using ultra-cold atoms in optical lattices. We discuss various types of static and dynamical curved spacetimes achievable by simple manipulations of the optical setup. Examples presented here contain two-dimensional spaces of positive and negative curvature as well as homogeneous cosmological models and metric waves. Most of them are extendable to three spatial dimensions. We mention some interesting phenomena of quantum field theory in curved spacetimes which might be simulated in such optical lattices loaded with bosonic or fermionic ultra-cold atoms. We also argue that methods of differential geometry can be used, as an alternative mathematical approach, for dealing with realistic inhomogeneous optical lattices.
The New Keynesian Phillips Curve
DEFF Research Database (Denmark)
Ólafsson, Tjörvi
This paper provides a survey on the recent literature on the new Keynesian Phillips curve: the controversies surrounding its microfoundation and estimation, the approaches that have been tried to improve its empirical fit and the challenges it faces adapting to the open-economy framework. The new...... Keynesian Phillips curve has been severely criticized for poor empirical dynamics. Suggested improvements involve making some adjustments to the standard sticky price framework, e.g. introducing backwardness and real rigidities, or abandoning the sticky price model and relying on models of inattentiveness......, learning or state-dependant pricing. The introduction of openeconomy factors into the new Keynesian Phillips curve complicate matters further as it must capture the nexus between price setting, inflation and the exchange rate. This is nevertheless a crucial feature for any model to be used for inflation...
Algebraic curves of maximal cyclicity
Caubergh, Magdalena; Dumortier, Freddy
2006-01-01
The paper deals with analytic families of planar vector fields, studying methods to detect the cyclicity of a non-isolated closed orbit, i.e. the maximum number of limit cycles that can locally bifurcate from it. It is known that this multi-parameter problem can be reduced to a single-parameter one, in the sense that there exist analytic curves in parameter space along which the maximal cyclicity can be attained. In that case one speaks about a maximal cyclicity curve (mcc) in case only the number is considered and of a maximal multiplicity curve (mmc) in case the multiplicity is also taken into account. In view of obtaining efficient algorithms for detecting the cyclicity, we investigate whether such mcc or mmc can be algebraic or even linear depending on certain general properties of the families or of their associated Bautin ideal. In any case by well chosen examples we show that prudence is appropriate.
Shock detachment from curved wedges
Mölder, S.
2017-03-01
Curved shock theory is used to show that the flow behind attached shocks on doubly curved wedges can have either positive or negative post-shock pressure gradients depending on the freestream Mach number, the wedge angle and the two wedge curvatures. Given enough wedge length, the flow near the leading edge can choke to force the shock to detach from the wedge. This local choking can preempt both the maximum deflection and the sonic criteria for shock detachment. Analytical predictions for detachment by local choking are supported by CFD results.
Shock detachment from curved wedges
Mölder, S.
2017-09-01
Curved shock theory is used to show that the flow behind attached shocks on doubly curved wedges can have either positive or negative post-shock pressure gradients depending on the freestream Mach number, the wedge angle and the two wedge curvatures. Given enough wedge length, the flow near the leading edge can choke to force the shock to detach from the wedge. This local choking can preempt both the maximum deflection and the sonic criteria for shock detachment. Analytical predictions for detachment by local choking are supported by CFD results.
Caloric Curves and Nuclear Expansion
Natowitz, J B; Ma, Y; Murray, M; Qin, L; Shlomo, S; Wada, R; Wang, J
2002-01-01
Nuclear caloric curves have been analyzed using an expanding Fermi gas hypothesis to extract average nuclear densities. In this approach the observed flattening of the caloric curves reflects progressively increasing expansion with increasing excitation energy. This expansion results in a corresponding decrease in the density and Fermi energy of the excited system. For nuclei of medium to heavy mass apparent densities $~0.3\\rho_0$ are reached at the higher excitation energies. The average densities derived in this manner are in good agreement with those derived using other, more complicated, techniques.
Curved branes with regular support
Energy Technology Data Exchange (ETDEWEB)
Antoniadis, Ignatios [Sorbonne Universites, LPTHE, UMR CNRS 7589, Paris (France); University of Bern, Albert Einstein Center for Fundamental Physics, ITP, Bern (Switzerland); Cotsakis, Spiros; Klaoudatou, Ifigeneia [American University of the Middle East, Department of Mathematics, P. O. Box 220, Dasman (Kuwait)
2016-09-15
We study spacetime singularities in a general five-dimensional braneworld with curved branes satisfying four-dimensional maximal symmetry. The bulk is supported by an analog of perfect fluid with the time replaced by the extra coordinate. We show that contrary to the existence of finite-distance singularities from the brane location in any solution with flat (Minkowski) branes, in the case of curved branes there are singularity-free solutions for a range of equations of state compatible with the null energy condition. (orig.)
The Complexity of Proving the Discrete Jordan Curve Theorem
Nguyen, Phuong
2010-01-01
The Jordan Curve Theorem (JCT) states that a simple closed curve divides the plane into exactly two connected regions. We formalize and prove the theorem in the context of grid graphs, under different input settings, in theories of bounded arithmetic that correspond to small complexity classes. The theory $V^0(2)$ (corresponding to $AC^0(2)$) proves that any set of edges that form disjoint cycles divides the grid into at least two regions. The theory $V^0$ (corresponding to $AC^0$) proves that any sequence of edges that form a simple closed curve divides the grid into exactly two regions. As a consequence, the Hex tautologies and the st-connectivity tautologies have polynomial size $AC^0(2)$-Frege-proofs, which improves results of Buss which only apply to the stronger proof system $TC^0$-Frege.
Interpolation and Polynomial Curve Fitting
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…
Principal Curves on Riemannian Manifolds.
Hauberg, Soren
2016-09-01
Euclidean statistics are often generalized to Riemannian manifolds by replacing straight-line interpolations with geodesic ones. While these Riemannian models are familiar-looking, they are restricted by the inflexibility of geodesics, and they rely on constructions which are optimal only in Euclidean domains. We consider extensions of Principal Component Analysis (PCA) to Riemannian manifolds. Classic Riemannian approaches seek a geodesic curve passing through the mean that optimizes a criteria of interest. The requirements that the solution both is geodesic and must pass through the mean tend to imply that the methods only work well when the manifold is mostly flat within the support of the generating distribution. We argue that instead of generalizing linear Euclidean models, it is more fruitful to generalize non-linear Euclidean models. Specifically, we extend the classic Principal Curves from Hastie & Stuetzle to data residing on a complete Riemannian manifold. We show that for elliptical distributions in the tangent of spaces of constant curvature, the standard principal geodesic is a principal curve. The proposed model is simple to compute and avoids many of the pitfalls of traditional geodesic approaches. We empirically demonstrate the effectiveness of the Riemannian principal curves on several manifolds and datasets.
Variability among polysulphone calibration curves
Energy Technology Data Exchange (ETDEWEB)
Casale, G R [University of Rome ' La Sapienza' , Physics Department, P.le A. Moro 2, I-00185, Rome (Italy); Borra, M [ISPESL - Istituto Superiore per la Prevenzione E la Sicurezza del Lavoro, Occupational Hygiene Department, Via Fontana Candida 1, I-0040 Monteporzio Catone (RM) (Italy); Colosimo, A [University of Rome ' La Sapienza' , Department of Human Physiology and Pharmacology, P.le A. Moro 2, I-00185, Rome (Italy); Colucci, M [ISPESL - Istituto Superiore per la Prevenzione E la Sicurezza del Lavoro, Occupational Hygiene Department, Via Fontana Candida 1, I-0040 Monteporzio Catone (RM) (Italy); Militello, A [ISPESL - Istituto Superiore per la Prevenzione E la Sicurezza del Lavoro, Occupational Hygiene Department, Via Fontana Candida 1, I-0040 Monteporzio Catone (RM) (Italy); Siani, A M [University of Rome ' La Sapienza' , Physics Department, P.le A. Moro 2, I-00185, Rome (Italy); Sisto, R [ISPESL - Istituto Superiore per la Prevenzione E la Sicurezza del Lavoro, Occupational Hygiene Department, Via Fontana Candida 1, I-0040 Monteporzio Catone (RM) (Italy)
2006-09-07
Within an epidemiological study regarding the correlation between skin pathologies and personal ultraviolet (UV) exposure due to solar radiation, 14 field campaigns using polysulphone (PS) dosemeters were carried out at three different Italian sites (urban, semi-rural and rural) in every season of the year. A polysulphone calibration curve for each field experiment was obtained by measuring the ambient UV dose under almost clear sky conditions and the corresponding change in the PS film absorbance, prior and post exposure. Ambient UV doses were measured by well-calibrated broad-band radiometers and by electronic dosemeters. The dose-response relation was represented by the typical best fit to a third-degree polynomial and it was parameterized by a coefficient multiplying a cubic polynomial function. It was observed that the fit curves differed from each other in the coefficient only. It was assessed that the multiplying coefficient was affected by the solar UV spectrum at the Earth's surface whilst the polynomial factor depended on the photoinduced reaction of the polysulphone film. The mismatch between the polysulphone spectral curve and the CIE erythemal action spectrum was responsible for the variability among polysulphone calibration curves. The variability of the coefficient was related to the total ozone amount and the solar zenith angle. A mathematical explanation of such a parameterization was also discussed.
Space curves, anholonomy and nonlinearity
Indian Academy of Sciences (India)
Radha Balakrishnan
2005-04-01
Using classical differential geometry, we discuss the phenomenon of anholonomy that gets associated with a static and a moving curve. We obtain the expressions for the respective geometric phases in the two cases and interpret them. We show that there is a close connection between anholonomy and nonlinearity in a wide class of nonlinear systems.
The New Keynesian Phillips Curve
DEFF Research Database (Denmark)
Ólafsson, Tjörvi
, learning or state-dependant pricing. The introduction of openeconomy factors into the new Keynesian Phillips curve complicate matters further as it must capture the nexus between price setting, inflation and the exchange rate. This is nevertheless a crucial feature for any model to be used for inflation...... forecasting in a small open economy like Iceland....
Murre, J.M.J.
2014-01-01
In this article, learning curves for foreign vocabulary words are investigated, distinguishing between a subject-specific learning rate and a material-specific parameter that is related to the complexity of the items, such as the number of syllables. Two experiments are described, one with Turkish w
The soil reference shrinkage curve
Chertkov, V Y
2014-01-01
A recently proposed model showed how a clay shrinkage curve is transformed to the soil shrinkage curve at the soil clay content higher than a critical one. The objective of the present work was to generalize this model to the soil clay content lower a critical one. I investigated (i) the reference shrinkage curve, that is, one without cracks; (ii) the superficial layer of aggregates, with changed pore structure compared with the intraaggregate matrix; and (iii) soils with sufficiently low clay content where there are large pores inside the intraaggregate clay (so-called lacunar pores). The methodology is based on detail accounting for different contributions to the soil volume and water content during shrinkage. The key point is the calculation of the lacunar pore volume variance at shrinkage. The reference shrinkage curve is determined by eight physical soil parameters: (1) oven-dried specific volume; (2) maximum swelling water content; (3) mean solid density; (4) soil clay content; (5) oven-dried structural...
Evolution of dust extinction curves in galaxy simulation
Hou, Kuan-Chou; Hirashita, Hiroyuki; Nagamine, Kentaro; Aoyama, Shohei; Shimizu, Ikkoh
2017-07-01
To understand the evolution of extinction curve, we calculate the dust evolution in a galaxy using smoothed particle hydrodynamic simulations incorporating stellar dust production, dust destruction in supernova shocks, grain growth by accretion and coagulation, and grain disruption by shattering. The dust species are separated into carbonaceous dust and silicate. The evolution of grain size distribution is considered by dividing grain population into large and small grains, which allows us to estimate extinction curves. We examine the dependence of extinction curves on the position, gas density and metallicity in the galaxy, and find that extinction curves are flat at t ≲ 0.3 Gyr because stellar dust production dominates the total dust abundance. The 2175 Å bump and far-ultraviolet (FUV) rise become prominent after dust growth by accretion. At t ≳ 3 Gyr, shattering works efficiently in the outer disc and low-density regions, so extinction curves show a very strong 2175 Å bump and steep FUV rise. The extinction curves at t ≳ 3 Gyr are consistent with the Milky Way extinction curve, which implies that we successfully included the necessary dust processes in the model. The outer disc component caused by stellar feedback has an extinction curve with a weaker 2175 Å bump and flatter FUV slope. The strong contribution of carbonaceous dust tends to underproduce the FUV rise in the Small Magellanic Cloud extinction curve, which supports selective loss of small carbonaceous dust in the galaxy. The snapshot at young ages also explains the extinction curves in high-redshift quasars.
The Complexity of Proving the Discrete Jordan Curve Theorem
Nguyen, Phuong; Cook, Stephen
2010-01-01
The Jordan Curve Theorem (JCT) states that a simple closed curve divides the plane into exactly two connected regions. We formalize and prove the theorem in the context of grid graphs, under different input settings, in theories of bounded arithmetic that correspond to small complexity classes. The theory $V^0(2)$ (corresponding to $AC^0(2)$) proves that any set of edges that form disjoint cycles divides the grid into at least two regions. The theory $V^0$ (corresponding to $AC^0$) proves tha...
BLOOD FLOW AND MACROMOLECULAR TRANSPORT IN CURVED BLOOD VESSELS
Institute of Scientific and Technical Information of China (English)
WEI Lan; WEN Gong-bi; TAN Wen-chang
2006-01-01
A numerical analysis of the steady/pulsatile flow and macromolecular (such as LDL and Albumin) transport in curved blood vessels was carried out. The computational results predict that the vortex of the secondary flow is time-dependent in the aortic arch.The concentration of macromolecule concentrates at the region of sharp curve, and the wall concentration at the outer part is higher than that at the inner part. Atherosclerosis and thrombosis are prone to develop in such regions with sharp flow.
A catalog of special plane curves
Lawrence, J Dennis
2014-01-01
Among the largest, finest collections available-illustrated not only once for each curve, but also for various values of any parameters present. Covers general properties of curves and types of derived curves. Curves illustrated by a CalComp digital incremental plotter. 12 illustrations.
Principal Curves on Riemannian Manifolds
DEFF Research Database (Denmark)
Hauberg, Søren
2015-01-01
Euclidean statistics are often generalized to Riemannian manifolds by replacing straight-line interpolations with geodesic ones. While these Riemannian models are familiar-looking, they are restricted by the inflexibility of geodesics, and they rely on constructions which are optimal only...... in Euclidean domains. We consider extensions of Principal Component Analysis (PCA) to Riemannian manifolds. Classic Riemannian approaches seek a geodesic curve passing through the mean that optimize a criteria of interest. The requirements that the solution both is geodesic and must pass through the mean tend...... from Hastie & Stuetzle to data residing on a complete Riemannian manifold. We show that for elliptical distributions in the tangent of spaces of constant curvature, the standard principal geodesic is a principal curve. The proposed model is simple to compute and avoids many of the pitfalls...
Invariance for Single Curved Manifold
Castro, Pedro Machado Manhaes de
2012-08-01
Recently, it has been shown that, for Lambert illumination model, solely scenes composed by developable objects with a very particular albedo distribution produce an (2D) image with isolines that are (almost) invariant to light direction change. In this work, we provide and investigate a more general framework, and we show that, in general, the requirement for such in variances is quite strong, and is related to the differential geometry of the objects. More precisely, it is proved that single curved manifolds, i.e., manifolds such that at each point there is at most one principal curvature direction, produce invariant is surfaces for a certain relevant family of energy functions. In the three-dimensional case, the associated energy function corresponds to the classical Lambert illumination model with albedo. This result is also extended for finite-dimensional scenes composed by single curved objects. © 2012 IEEE.
Supersymmetric Spacetimes from Curved Superspace
Kuzenko, Sergei M
2015-01-01
We review the superspace technique to determine supersymmetric spacetimes in the framework of off-shell formulations for supergravity in diverse dimensions using the case of 3D N=2 supergravity theories as an illustrative example. This geometric formalism has several advantages over other approaches advocated in the last four years. Firstly, the infinitesimal isometry transformations of a given curved superspace form, by construction, a finite-dimensional Lie superalgebra, with its odd part corresponding to the rigid supersymmetry transformations. Secondly, the generalised Killing spinor equation, which must be obeyed by the supersymmetry parameters, is a consequence of the more fundamental superfield Killing equation. Thirdly, general rigid supersymmetric theories on a curved spacetime are readily constructed in superspace by making use of the known off-shell supergravity-matter couplings and restricting them to the background chosen. It is the superspace techniques which make it possible to generate arbitra...
Curved canals: Ancestral files revisited
Directory of Open Access Journals (Sweden)
Jain Nidhi
2008-01-01
Full Text Available The aim of this article is to provide an insight into different techniques of cleaning and shaping of curved root canals with hand instruments. Although a plethora of root canal instruments like ProFile, ProTaper, LightSpeed ® etc dominate the current scenario, the inexpensive conventional root canal hand files such as K-files and flexible files can be used to get optimum results when handled meticulously. Special emphasis has been put on the modifications in biomechanical canal preparation in a variety of curved canal cases. This article compiles a series of clinical cases of root canals with curvatures in the middle and apical third and with S-shaped curvatures that were successfully completed by employing only conventional root canal hand instruments.
A Study of Hyperelliptic Curves in Cryptography
Directory of Open Access Journals (Sweden)
Reza Alimoradi
2016-08-01
Full Text Available Elliptic curves are some specific type of curves known as hyper elliptic curves. Compared to the integer factorization problem(IFP based systems, using elliptic curve based cryptography will significantly decrease key size of the encryption. Therefore, application of this type of cryptography in systems that need high security and smaller key size has found great attention. Hyperelliptic curves help to make key length shorter. Many investigations are done with regard to improving computations, hardware and software implementation of these curves, their security and resistance against attacks. This paper studies and analyzes researches done about security and efficiency of hyperelliptic curves.
1992-12-16
12 = (K,, + )- (29) K 2 (see [3]). The parameter KM represents the amplitude of the periodic curva - ture function and sm denotes the value at which K...Additamentum De curvis elasticis. Methodus Inveniendi Lineas Curvas Maximi Minimive Proprietate Gaudentes, Ser. 1., Vol. 24, Lausanne 1744. 17 [10...Mathematical Theory of Elasticity. 4th. ed., Cambridge University Press, 1927. [12] G. Nielson. Bernstein/ Bezier Curves and Splines on Spheres based upon
Accelerating Around an Unbanked Curve
Mungan, Carl E.
2006-02-01
The December 2004 issue of TPT presented a problem concerning how a car should accelerate around an unbanked curve of constant radius r starting from rest if it is to avoid skidding. Interestingly enough, two solutions were proffered by readers.2 The purpose of this note is to compare and contrast the two approaches. Further experimental investigation of various turning strategies using a remote-controlled car and overhead video analysis could make for an interesting student project.
An Analysis of the Shapes of Interstellar Extinction Curves. V. The IR-Through-UV Curve Morphology
Fitzpatrick, E L
2007-01-01
We study the IR-through-UV interstellar extinction curves towards 328 Galactic B and late-O stars. We use a new technique which employs stellar atmosphere models in lieu of unreddened "standard" stars. This technique is capable of virtually eliminating spectral mismatch errors in the curves. It also allows a quantitative assessment of the errors and enables a rigorous testing of the significance of relationships between various curve parameters, regardless of whether their uncertainties are correlated. Analysis of the curves gives the following results: (1) In accord with our previous findings, the central position of the 2175 A extinction bump is mildly variable, its width is highly variable, and the two variations are unrelated. (2) Strong correlations are found among some extinction properties within the UV region, and within the IR region. (3) With the exception of a few curves with extreme (i.e., large) values of R(V), the UV and IR portions of Galactic extinction curves are not correlated with each othe...
Automatic detection of scoliotic curves in posteroanterior radiographs.
Duong, Luc; Cheriet, Farida; Labelle, Hubert
2010-05-01
Spinal deformities are diagnosed using posteroanterior (PA) radiographs. Automatic detection of the spine on conventional radiographs would be of interest to quantify curve severity, would help reduce observer variability and would allow large-scale retrospective studies on radiographic databases. The goal of this paper is to present a new method for automatic detection of spinal curves from a PA radiograph. A region of interest (ROI) is first extracted according to the 2-D shape variability of the spine obtained from a set of PA radiographs of scoliotic patients. This region includes 17 bounding boxes delimiting each vertebral level from T1 to L5. An adaptive filter combining shock with complex diffusion is used to individually restore the image of each vertebral level. Then, texture descriptors of small block elements are computed and submitted for training to support vector machines (SVM). Vertebral body's locations are thereby inferred for a particular vertebral level. The classifications of block elements for all 17 SVMs are identified in the image and a voting system is introduced to cumulate correctly predicted blocks. A spline curve is then fitted through the centers of the predicted vertebral regions and compared to a manual identification using a Student t-test. A clinical validation is performed using 100 radiographs of scoliotic patients (not used for training) and the detected spinal curve is found to be statistically similar (p < 0.05) in 93% of cases to the manually identified curve.
Macdonald formula for curves with planar singularities
Maulik, Davesh
2011-01-01
We generalize Macdonald's formula for the cohomology of Hilbert schemes of points on a curve from smooth curves to curves with planar singularities: we relate the cohomology of the Hilbert schemes to the cohomology of the compactified Jacobian of the curve. The new formula is a consequence of a stronger identity between certain perverse sheaves defined by a family of curves satisfying mild conditions, whose proof makes an essential use of Ng\\^o's support theorem for compactified Jacobians.
LINS Curve in Romanian Economy
Directory of Open Access Journals (Sweden)
Emilian Dobrescu
2016-02-01
Full Text Available The paper presents theoretical considerations and empirical evidence to test the validity of the Laffer in Narrower Sense (LINS curve as a parabola with a maximum. Attention is focused on the so-called legal-effective tax gap (letg. The econometric application is based on statistical data (1990-2013 for Romania as an emerging European economy. Three cointegrating regressions (fully modified least squares, canonical cointegrating regression and dynamic least squares and three algorithms, which are based on instrumental variables (two-stage least squares, generalized method of moments, and limited information maximum likelihood, are involved.
Principal -bundles on Nodal Curves
Indian Academy of Sciences (India)
Usha N Bhosle
2001-08-01
Let be a connected semisimple affine algebraic group defined over . We study the relation between stable, semistable -bundles on a nodal curve and representations of the fundamental group of . This study is done by extending the notion of (generalized) parabolic vector bundles to principal -bundles on the desingularization of and using the correspondence between them and principal -bundles on . We give an isomorphism of the stack of generalized parabolic bundles on with a quotient stack associated to loop groups. We show that if is simple and simply connected then the Picard group of the stack of principal -bundles on is isomorphic to ⊕ , being the number of components of .
Sound propagation over curved barriers
Pierce, Allan D.; Main, Geoffrey L.; Kearns, James A.; Hsieh, H.-A.
1986-01-01
Wide barriers with curved tops are studied with emphasis placed on circumstances whereby the local radius of curvature R of the barrier is continuous along the surface and is large compared to a wavelength. Results analogous to those given by Hayek et al. (1978) are reviewed and extended to cases where the radius of curvature and the surface impedance may vary with position. Circumstances not easily interpreted within the framework of the model proposed by Keller (1956) and Hayek et al. are also considered.
Reconfigurable Double-Curved Mould
DEFF Research Database (Denmark)
Raun, Christian; Kirkegaard, Poul Henning
2012-01-01
. This happens fast, automatic and without production of waste, and the manipulated surface is fair and robust, eliminating the need for additional, manual treatment. Limitations to the possibilities of the flexible form are limited curvature and limited level of detail, making it especially suited for larger......, double curved surfaces like facades or walls, where the curvature of each element is relatively small in comparison to the overall shape. In the proposed dynamic mould system, where only a set of points is defined, a stiff membrane interpolates the surface between points. To function as a surface...
Membranes Wrapped on Holomorphic Curves
Gauntlett, J P; Pakis, S; Waldram, D; Gauntlett, Jerome P.; Kim, Nakwoo; Pakis, Stathis; Waldram, Daniel
2002-01-01
We construct supergravity solutions dual to the twisted field theories arising when M-theory membranes wrap holomorphic curves in Calabi-Yau n-folds. The solutions are constructed in an Abelian truncation of maximal D=4 gauged supergravity and then uplifted to D=11. For four-folds and five-folds we find new smooth AdS/CFT examples and for all cases we analyse the nature of the singularities that arise. Our results provide an interpretation of certain charged topological AdS black holes. We also present the generalised calibration two-forms for the solutions.
Curved Radio Spectra of Weak Cluster Shocks
Kang, Hyesung
2015-01-01
We explore a diffusive shock acceleration (DSA) model for radio relics in which a spherical shock impinges on a magnetized cloud of fossil relativistic electrons in the cluster periphery. Such a scenario could explain uniformity of the surface brightness and spectral curvature in the integrated spectra of thin arc-like radio relics. 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. The surface brightness profile of radio-emitting postshock region and the volume-integrated radio spectrum are calculated as well. We find that the observed width of the Sausage relic can be explained reasonably well by shocks with speed $u_s \\sim 3,000 \\kms$ and sonic Mach number $M_s \\sim 3$. These shocks produce curved radio spectra that steepen gradually over $(0.1-10) \
Lyellian curves in paleontology: Possibilities and limitations
Stanley, Steven M.; Addicott, Warren O.; Chinzei, Kiyotaka
1980-09-01
Since the birth of modern geology, Cenozoic deposits have commonly been dated according to Lyellian percentages (proportions of living species within fossil faunas), but this approach has never been tested. To remedy this situation, we have calculated Lyellian percentages for gastropod and bivalve faunas of Japan and western North America. When plotted against geologic age (determined by independent methods), the percentages for each class form a narrow band that reveals similar patterns of extinction for the two regions and an absence of major pulses of extinction. The plots thus seem to represent useful “standard” curves but display enough spread of data to cast doubt on the value of Lyellian percentages to chronostratigraphy. Our plots do have many other useful applications: (1) They reveal differences in regional patterns of extinction; in particular, they document a Pleistocene mass extinction of Mollusca in the confined seas of the tropical Americas and an unusually low rate of extinction in the enormous tropical Indo-Pacific region. (2) They indicate that gastropods are characterized by higher rates of extinction than bivalves. (3) They provide a mechanism for evaluating differences in rates of extinction between discrete subgroups of taxa, such as tropical species and temperate species, or species with planktic larvae and species with nonplanktic larvae.
Differential geometry and topology of curves
Animov, Yu
2001-01-01
Differential geometry is an actively developing area of modern mathematics. This volume presents a classical approach to the general topics of the geometry of curves, including the theory of curves in n-dimensional Euclidean space. The author investigates problems for special classes of curves and gives the working method used to obtain the conditions for closed polygonal curves. The proof of the Bakel-Werner theorem in conditions of boundedness for curves with periodic curvature and torsion is also presented. This volume also highlights the contributions made by great geometers. past and present, to differential geometry and the topology of curves.
Smarandache Curves in Minkowski Space-time
Turgut, Melih; Yilmaz, Suha
2008-01-01
A regular curve in Minkowski space-time, whose position vector is composed by Frenet frame vectors on another regular curve, is called a Smarandache Curve. In this paper, we define a special case of such curves and call it Smarandache TB2 Curves in the space E41. Moreover, we compute formulas of its Frenet apparatus according to base curve via the method expressed in [3]. By this way, we obtain an another orthonormal frame of E41.
Flow characteristics of curved ducts
Directory of Open Access Journals (Sweden)
Rudolf P.
2007-10-01
Full Text Available Curved channels are very often present in real hydraulic systems, e.g. curved diffusers of hydraulic turbines, S-shaped bulb turbines, fittings, etc. Curvature brings change of velocity profile, generation of vortices and production of hydraulic losses. Flow simulation using CFD techniques were performed to understand these phenomena. Cases ranging from single elbow to coupled elbows in shapes of U, S and spatial right angle position with circular cross-section were modeled for Re = 60000. Spatial development of the flow was studied and consequently it was deduced that minor losses are connected with the transformation of pressure energy into kinetic energy and vice versa. This transformation is a dissipative process and is reflected in the amount of the energy irreversibly lost. Least loss coefficient is connected with flow in U-shape elbows, biggest one with flow in Sshape elbows. Finally, the extent of the flow domain influenced by presence of curvature was examined. This isimportant for proper placement of mano- and flowmeters during experimental tests. Simulations were verified with experimental results presented in literature.
Capacity theory on algebraic curves
Rumely, Robert S
1989-01-01
Capacity is a measure of size for sets, with diverse applications in potential theory, probability and number theory. This book lays foundations for a theory of capacity for adelic sets on algebraic curves. Its main result is an arithmetic one, a generalization of a theorem of Fekete and Szegö which gives a sharp existence/finiteness criterion for algebraic points whose conjugates lie near a specified set on a curve. The book brings out a deep connection between the classical Green's functions of analysis and Néron's local height pairings; it also points to an interpretation of capacity as a kind of intersection index in the framework of Arakelov Theory. It is a research monograph and will primarily be of interest to number theorists and algebraic geometers; because of applications of the theory, it may also be of interest to logicians. The theory presented generalizes one due to David Cantor for the projective line. As with most adelic theories, it has a local and a global part. Let /K be a smooth, complet...
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
2013-06-04
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.
CURVED OPEN CHANNEL FLOW ON VEGETATION ROUGHENED INNER BANK
Institute of Scientific and Technical Information of China (English)
HUAI Wen-xin; LI Cheng-guang; ZENG Yu-hong; QIAN Zhong-dong; YANG Zhong-hua
2012-01-01
A RNG k-ε numerical model together with a laboratory measurement with Micro ADV are adopted to investigate the flow through a 180° curved open channel (a 4 m straight inflow section,a 180° curved section,and a 4m straight outflow section)partially covered with rigid vegetations on its inner bank.Under the combined action of the vegetation and the bend flow,the flow structure is complex.The stream-wise velocities in the vegetation region are much smaller than those in the non-vegetation region due to the retardation caused by the vegetation.For the same reason,no clear circulation is found in the vegetated region,while in the non-vegetation region,a slight counter-rotating circulation is found near the outer bank at both 90° and downstream curved cross-sections.A comparison between the numerical prediction and the laboratory measurement shows that the RNG k- model can well predict the flow structure of the bend flow with vegetation.Furthermore,the shear stress is analyzed based on the numerical prediction.The much smaller value in the inner vegetated region indicates that the vegetation can effectively protect the fiver bank from scouting and erosion,in other words,the sediment is more likely to be deposited in the vegetation region.
Curve Length Estimation using Vertix Chain Code Curve Length Estimation
Directory of Open Access Journals (Sweden)
Habibollah Haron
2010-09-01
Full Text Available Most of the applications in image analysis are based on Freeman chain code. In this paper, for the first time, vertex chain code (VCC proposed by Bribiesca is applied to improve length estimation of the 2D digitized curve. The chain code has some preferences such as stable in shifting, turning, mirroring movement of image and has normalized starting point. Due to the variety of length estimator methods, we focused on the three specific techniques. First, the way Bribiesca proposed which is based on counting links between vertices; second, based on maximum length digital straight segments (DSSs and lastly local metrics. The results of these length estimators with the real perimeter are compared. Results thus obtained exhibits thatlength estimation using VCC is nearest to the actual length.
Flood damage curves for consistent global risk assessments
de Moel, Hans; Huizinga, Jan; Szewczyk, Wojtek
2016-04-01
Assessing potential damage of flood events is an important component in flood risk management. Determining direct flood damage is commonly done using depth-damage curves, which denote the flood damage that would occur at specific water depths per asset or land-use class. Many countries around the world have developed flood damage models using such curves which are based on analysis of past flood events and/or on expert judgement. However, such damage curves are not available for all regions, which hampers damage assessments in those regions. Moreover, due to different methodologies employed for various damage models in different countries, damage assessments cannot be directly compared with each other, obstructing also supra-national flood damage assessments. To address these problems, a globally consistent dataset of depth-damage curves has been developed. This dataset contains damage curves depicting percent of damage as a function of water depth as well as maximum damage values for a variety of assets and land use classes (i.e. residential, commercial, agriculture). Based on an extensive literature survey concave damage curves have been developed for each continent, while differentiation in flood damage between countries is established by determining maximum damage values at the country scale. These maximum damage values are based on construction cost surveys from multinational construction companies, which provide a coherent set of detailed building cost data across dozens of countries. A consistent set of maximum flood damage values for all countries was computed using statistical regressions with socio-economic World Development Indicators from the World Bank. Further, based on insights from the literature survey, guidance is also given on how the damage curves and maximum damage values can be adjusted for specific local circumstances, such as urban vs. rural locations, use of specific building material, etc. This dataset can be used for consistent supra
Transition curves for highway geometric design
Kobryń, Andrzej
2017-01-01
This book provides concise descriptions of the various solutions of transition curves, which can be used in geometric design of roads and highways. It presents mathematical methods and curvature functions for defining transition curves. .
2002-01-01
The Atlas of Stress-Strain Curves, Second Edition is substantially bigger in page dimensions, number of pages, and total number of curves than the previous edition. It contains over 1,400 curves, almost three times as many as in the 1987 edition. The curves are normalized in appearance to aid making comparisons among materials. All diagrams include metric (SI) units, and many also include U.S. customary units. All curves are captioned in a consistent format with valuable information including (as available) standard designation, the primary source of the curve, mechanical properties (including hardening exponent and strength coefficient), condition of sample, strain rate, test temperature, and alloy composition. Curve types include monotonic and cyclic stress-strain, isochronous stress-strain, and tangent modulus. Curves are logically arranged and indexed for fast retrieval of information. The book also includes an introduction that provides background information on methods of stress-strain determination, on...
Whitney's formulas for curves on surfaces
Burman, Yurii
2009-01-01
The classical Whitney formula relates the number of times an oriented plane curve cuts itself to its rotation number and the index of a base point. In this paper we generalize Whitney's formula to curves on an oriented punctured surface. To define analogs of the rotation number and the index of a base point of a curve, we fix an arbitrary vector field on the surface. Similar formulas are obtained for non-based curves.
Logging and Agricultural Residue Supply Curves for the Pacific Northwest
Energy Technology Data Exchange (ETDEWEB)
Kerstetter, James D.; Lyons, John Kim
2001-01-01
This report quantified the volume of logging residues at the county level for current timber harvests. The cost of recovering logging residues was determined for skidding, yearding, loading, chipping and transporting the residues. Supply curves were developed for ten candidate conversion sites in the Pacific Northwest Region. Agricultural field residues were also quantified at the county level using five-year average crop yields. Agronomic constraints were applied to arrive at the volumes available for energy use. Collection costs and transportation costs were determined and supply curves generated for thirteen candidate conversion sites.
CHAOTIC TRANSIENTS IN A CURVED FLUID CONVEYING TUBE
Institute of Scientific and Technical Information of China (English)
Ni Qiao; Wang Lin; Qian Qin
2005-01-01
The chaotic transients of a curved fluid conveying tube subjected to a nonlinear foundation are investigated. The assumption of the inextensibility of the tube is applied to derive the nonlinear differential equation of motion via the Newtonian approach, with the differential quadrature method used to discretize the curved tube model in the spatial domain. And the nonlinear dynamic motion equation is obtained. The numerical analysis shows that, the final steady states are sensitive to the initial system conditions in a large parameter region of the fluid speed. This phenomenon of chaotic transients is infrequent for fluid conveying tubes.
The antiproton depth–dose curve in water
Bassler, N; Jäkel, O; Knudsen, H V; Kovacevic, S
2008-01-01
We have measured the depth–dose curve of 126 MeV antiprotons in a water phantom using ionization chambers. Since the antiproton beam provided by CERN has a pulsed structure and possibly carries a high-LET component from the antiproton annihilation, it is necessary to correct the acquired charge for ion recombination effects. The results are compared with Monte Carlo calculations and were found to be in good agreement. Based on this agreement we calculate the antiproton depth–dose curve for antiprotons and compare it with that for protons and find a doubling of the physical dose in the peak region for antiprotons.
Ait-Haddou, Rachid
2013-02-01
We show that the generalized Bernstein bases in Müntz spaces defined by Hirschman and Widder (1949) and extended by Gelfond (1950) can be obtained as pointwise limits of the Chebyshev–Bernstein bases in Müntz spaces with respect to an interval [a,1][a,1] as the positive real number a converges to zero. Such a realization allows for concepts of curve design such as de Casteljau algorithm, blossom, dimension elevation to be transferred from the general theory of Chebyshev blossoms in Müntz spaces to these generalized Bernstein bases that we termed here as Gelfond–Bernstein bases. The advantage of working with Gelfond–Bernstein bases lies in the simplicity of the obtained concepts and algorithms as compared to their Chebyshev–Bernstein bases counterparts.
Bacterial streamers in curved microchannels
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.
Counting rational points on cubic curves
Institute of Scientific and Technical Information of China (English)
HEATH-BROWN; Roger; TESTA; Damiano
2010-01-01
We prove upper bounds for the number of rational points on non-singular cubic curves defined over the rationals.The bounds are uniform in the curve and involve the rank of the corresponding Jacobian.The method used in the proof is a combination of the "determinant method" with an m-descent on the curve.
Optimal investment in learning-curve technologies
Della Seta, M.; Gryglewicz, S.; Kort, P.M.
2012-01-01
We study optimal investment in technologies characterized by the learning curve. There are two investment patterns depending on the shape of the learning curve. If the learning process is slow, firms invest relatively late and on a larger scale. If the curve is steep, firms invest earlier and on a s
A STUDY ON JIG DISTRIBUTION CURVE TRANSFORMATION
Institute of Scientific and Technical Information of China (English)
路迈西; 常大山; 郭珍旭
1991-01-01
An investigation of the errors resulted from distribution curve transformations using six different methods was made on the basis of 61 sets of jig performance test data from the coal preparation plants in China. The results indicate that minimum error occurred when distribution curves were transformed by keeping imperfection I constant. Generalized distribution curves are developed for jigs and their applications are discussed.
The Bezout Number of Piecewise Algebraic Curves
Institute of Scientific and Technical Information of China (English)
Dian Xuan GONG; Ren Hong WANG
2012-01-01
Based on the discussion of the number of roots of univariate spline and the common zero points of two piecewise algebraic curves,a lower upbound of Bezout number of two piecewise algebraic curves on any given non-obtuse-angled triangulation is found.Bezout number of two piecewise algebraic curves on two different partitions is also discussed in this paper.
Automated Blazar Light Curves Using Machine Learning
Energy Technology Data Exchange (ETDEWEB)
Johnson, Spencer James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-07-27
This presentation describes a problem and methodology pertaining to automated blazar light curves. Namely, optical variability patterns for blazars require the construction of light curves and in order to generate the light curves, data must be filtered before processing to ensure quality.
AKLSQF - LEAST SQUARES CURVE FITTING
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.
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.
Method of construction spatial transition curve
Directory of Open Access Journals (Sweden)
S.V. Didanov
2013-04-01
Full Text Available Purpose. The movement of rail transport (speed rolling stock, traffic safety, etc. is largely dependent on the quality of the track. In this case, a special role is the transition curve, which ensures smooth insertion of the transition from linear to circular section of road. The article deals with modeling of spatial transition curve based on the parabolic distribution of the curvature and torsion. This is a continuation of research conducted by the authors regarding the spatial modeling of curved contours. Methodology. Construction of the spatial transition curve is numerical methods for solving nonlinear integral equations, where the initial data are taken coordinate the starting and ending points of the curve of the future, and the inclination of the tangent and the deviation of the curve from the tangent plane at these points. System solutions for the numerical method are the partial derivatives of the equations of the unknown parameters of the law of change of torsion and length of the transition curve. Findings. The parametric equations of the spatial transition curve are calculated by finding the unknown coefficients of the parabolic distribution of the curvature and torsion, as well as the spatial length of the transition curve. Originality. A method for constructing the spatial transition curve is devised, and based on this software geometric modeling spatial transition curves of railway track with specified deviations of the curve from the tangent plane. Practical value. The resulting curve can be applied in any sector of the economy, where it is necessary to ensure a smooth transition from linear to circular section of the curved space bypass. An example is the transition curve in the construction of the railway line, road, pipe, profile, flat section of the working blades of the turbine and compressor, the ship, plane, car, etc.
Cubic Curves, Finite Geometry and Cryptography
Bruen, A A; Wehlau, D L
2011-01-01
Some geometry on non-singular cubic curves, mainly over finite fields, is surveyed. Such a curve has 9,3,1 or 0 points of inflexion, and cubic curves are classified accordingly. The group structure and the possible numbers of rational points are also surveyed. A possible strengthening of the security of elliptic curve cryptography is proposed using a `shared secret' related to the group law. Cubic curves are also used in a new way to construct sets of points having various combinatorial and geometric properties that are of particular interest in finite Desarguesian planes.
On Self-growing Modeling for Curves
Institute of Scientific and Technical Information of China (English)
HUANG Dong-zhao; ZHU Zhi-hong; ZHOU Hui-cheng; SHI Han-min
2008-01-01
This paperpresents a novel curoe modeling method based on controlling rules of the shaping technique.The method describes the curve based on steplength and turning angle,and the characteristics of the curve near a point.Then it introduces the process to extract" growing-rules"for 2D and 3D curves described by familiar analytical expressions and curvature-torsion expressions.Examples of selfgrowing modeling for familiar analytical curves are presented.New curves are obtained by designing the grow-rules;corresponding examples are also presented.
Koch Curves: Rewriting System, Geometry and Application
Directory of Open Access Journals (Sweden)
Mamta Rani
2011-01-01
Full Text Available Problem statement: Recently, new Koch curves have been generated by dividing the initiator into three unequal parts. There is no formal rewriting system to generate such kind of curves. Approach: It is required to measure the new changed geometrical properties. Generalized rewriting systems for the new Koch curves have been developed. Results: New formulas have been given to measure their geometrical properties. Conclusion/Recommendations: The geometrical properties of new Koch curves make them more suitable as antennas in wireless communication than the conventional Koch curve.
Electromagnetic field limits set by the V-Curve.
Energy Technology Data Exchange (ETDEWEB)
Warne, Larry Kevin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jorgenson, Roy Eberhardt [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hudson, Howard Gerald [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2014-07-01
When emitters of electromagnetic energy are operated in the vicinity of sensitive components, the electric field at the component location must be kept below a certain level in order to prevent the component from being damaged, or in the case of electro-explosive devices, initiating. The V-Curve is a convenient way to set the electric field limit because it requires minimal information about the problem configuration. In this report we will discuss the basis for the V-Curve. We also consider deviations from the original V-Curve resulting from inductive versus capacitive antennas, increases in directivity gain for long antennas, decreases in input impedance when operating in a bounded region, and mismatches dictated by transmission line losses. In addition, we consider mitigating effects resulting from limited antenna sizes.
A New Curve Fitting Method for Forming Limit Experimental Data
Institute of Scientific and Technical Information of China (English)
Jieshi CHEN; Xianbin ZHOU
2005-01-01
The forming limit curve (FLC) can be obtained by. means of curve fitting the limit strain points of different strain paths. The theory of percent regression analysis is applied to the curve fitting of forming limit experimental data.Forecast intervals of FLC percentiles can be calculated. Thus reliability and confidence level can be considered. The theoretical method to get the limits of limit strain points distributing region is presented, and the FLC position can be adjusted according to practical requirement. Method for establishing FLC with high reliability using small samples is presented at the same time. This method can make full use of the current experimental data and the previous data.Compared with the traditional method that can only use current experimental data, fewer specimens are required in the present method to obtain the same precision and the result is more accurate with the same number of specimens.
Self-similar field dependent curves for a Heusler alloy
Energy Technology Data Exchange (ETDEWEB)
Ovichi, Maryam, E-mail: movichi@gwmail.gwu.edu [Department of Electrical and Computer Engineering, The George Washington University, Washington, DC (United States); ElBidweihy, Hatem; Ghahremani, Mohammadreza; Della Torre, Edward; Bennett, Lawrence H. [Department of Electrical and Computer Engineering, The George Washington University, Washington, DC (United States); Johnson, Francis; Zou, Min [GE Global Research, Niskayuna, NY 12309 (United States)
2014-02-15
Heusler alloys feature both regular and inverse magnetocaloric effects (MCE) near room temperature as they undergo two different transitions. A temperature scaling methodology to obtain self-similar field dependent curves for materials exhibiting one first-order transition has been previously presented. In this paper, this methodology is modified and extended to obtain self-similar curves for a Ni{sub 51}Mn{sub 32.8}In{sub 16.8} Heusler alloy undergoing two transitions near room temperature. Using this method, the collapsed curve reflects the cluster compositions in the mixed-state regions. The results of characterizing the dual transitions of Heusler alloys and establishing a new model will allow the data to be better analyzed and thus more easily predicted.
Curved Radio Spectra of Weak Cluster Shocks
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.
Directory of Open Access Journals (Sweden)
Roberto A. Cecílio
2003-12-01
Full Text Available As equações de chuvas intensas representam excelente alternativa para a determinação das precipitações críticas utilizadas em projetos de engenharia; contudo, a sua determinação é muito trabalhosa. No Brasil, entretanto, dispõe-se, em diversos Estados, de um expressivo número de equações, o que torna possível a obtenção, por interpolação, dos parâmetros da equação de chuvas intensas para locais em que estes não são conhecidos. Neste trabalho compararam-se, considerando-se as informações disponíveis em 171 localidades do Estado de Minas Gerais, 625 diferentes combinações entre os quatro parâmetros da equação de chuvas intensas ("K", "a", "b" e "c" interpolados com a utilização da metodologia do inverso da potência da distância, através de cinco diferentes potências. Percebeu-se, em todas as combinações, tendência de superestimativa da intensidade de precipitação. A interpolação de "K" e "c" com o inverso da quinta potência da distância, "a" com o inverso da distância e "b" com o inverso do cubo da distância, apresentou melhores resultados na estimativa da intensidade de precipitação.Intense precipitation equations represent an excellent alternative to determinate critical rainfalls used in engineering designs but its obtainment is time-consuming. However, in some Brazilian States a great number of these equations have been determined for several places, permitting to obtain the equation parameters, by interpolation, for the places where these still have not bean known. In this paper 625 different combinations were compared for the four intense precipitation parameters ("K", "a", "b" and "c" interpolated by the inverse distance to a power method (using five different powers. Data from 171 places located in Minas Gerais State were used. In all the combinations, a tendency of overestimation was noticed for the precipitation intensity. "K" and "c" parameters interpolated by the inverse distance to the fifth power, "a" interpolated by the inverse distance of the first power and "b" by the inverse distance to the third power showed better results in precipitation intensity prediction.
The South Carolina bridge-scour envelope curves
Benedict, Stephen T.; Feaster, Toby D.; Caldwell, Andral
2016-09-30
The U.S. Geological Survey, in cooperation with the South Carolina Department of Transportation, conducted a series of three field investigations to evaluate historical, riverine bridge scour in the Piedmont and Coastal Plain regions of South Carolina. These investigations included data collected at 231 riverine bridges, which lead to the development of bridge-scour envelope curves for clear-water and live-bed components of scour. The application and limitations of the South Carolina bridge-scour envelope curves were documented in four reports, each report addressing selected components of bridge scour. The current investigation (2016) synthesizes the findings of these previous reports into a guidance manual providing an integrated procedure for applying the envelope curves. Additionally, the investigation provides limited verification for selected bridge-scour envelope curves by comparing them to field data collected outside of South Carolina from previously published sources. Although the bridge-scour envelope curves have limitations, they are useful supplementary tools for assessing the potential for scour at riverine bridges in South Carolina.
Is the tautochrone curve unique?
Terra, Pedro; Farina, C
2016-01-01
The answer to this question is no. In fact, in addition to the solution first obtained by Christiaan Huygens in 1658, given by the cycloid, we show that there is an infinite number of tautochrone curves. With this goal, we start by briefly reviewing an the problem of finding out the possible potential energies that lead to periodic motions of a particle whose period is a given function of its mechanical energy. There are infinitely many solutions, called sheared potentials. As an interesting example, we show that a P\\"oschl-Teller and the one-dimensional Morse potentials are sheared relative to one another for negative energies, clarifying why they share the same periods of oscillations for their bounded solutions. We then consider periodic motions of a particle sliding without friction over a track around its minimum under the influence of an uniform gravitational field. After a brief historical survey of the tautochrone problem we show that, given the period of oscillations, there is an infinity of tracks w...
Is the tautochrone curve unique?
Terra, Pedro; de Melo e Souza, Reinaldo; Farina, C.
2016-12-01
We show that there are an infinite number of tautochrone curves in addition to the cycloid solution first obtained by Christiaan Huygens in 1658. We begin by reviewing the inverse problem of finding the possible potential energy functions that lead to periodic motions of a particle whose period is a given function of its mechanical energy. There are infinitely many such solutions, called "sheared" potentials. As an interesting example, we show that a Pöschl-Teller potential and the one-dimensional Morse potentials are sheared relative to one another for negative energies, clarifying why they share the same oscillation periods for their bounded solutions. We then consider periodic motions of a particle sliding without friction over a track around its minimum under the influence of a constant gravitational field. After a brief historical survey of the tautochrone problem we show that, given the oscillation period, there is an infinity of tracks that lead to the same period. As a bonus, we show that there are infinitely many tautochrones.
Algebraic points on meromorphic curves
Herblot, Mathilde
2012-01-01
The classic Schneider-Lang theorem in transcendence theory asserts that there are only finitely many points at which algebraically independent complex meromorphic functions of finite order of growth can simultaneously take values in a number field, when satisfying a polynomial differential equation with coefficients in this given number field. In this article, we are interested in generalizing this theorem in two directions. First, instead of considering meromorphic functions on C we consider holomorphic maps on an affine curve over the field C or C_p. This extends a statement of D. Bertrand, which applies to meromorphic functions on P^1(C) or P^1(C_p) minus a finite subset of points. Secondly, we deal with algebraic values taken by the functions, instead of rational values as in the classic setting, inspired by a work of D. Bertrand. We prove a geometric statement extending those two results, using the slopes method, written in the language of Arakelov geometry. In the complex case, we recover a special case...
Quantum fields in curved spacetime
Energy Technology Data Exchange (ETDEWEB)
Hollands, Stefan, E-mail: stefan.hollands@uni-leipzig.de [Universität Leipzig, Institut für Theoretische Physik, Brüderstrasse 16, D-04103 Leipzig (Germany); Wald, Robert M., E-mail: rmwa@uchicago.edu [Enrico Fermi Institute and Department of Physics, University of Chicago, Chicago, IL 60637 (United States)
2015-04-16
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.
Simulations of Closed Timelike Curves
Brun, Todd A.; Wilde, Mark M.
2017-03-01
Proposed models of closed timelike curves (CTCs) have been shown to enable powerful information-processing protocols. We examine the simulation of models of CTCs both by other models of CTCs and by physical systems without access to CTCs. We prove that the recently proposed transition probability CTCs (T-CTCs) are physically equivalent to postselection CTCs (P-CTCs), in the sense that one model can simulate the other with reasonable overhead. As a consequence, their information-processing capabilities are equivalent. We also describe a method for quantum computers to simulate Deutschian CTCs (but with a reasonable overhead only in some cases). In cases for which the overhead is reasonable, it might be possible to perform the simulation in a table-top experiment. This approach has the benefit of resolving some ambiguities associated with the equivalent circuit model of Ralph et al. Furthermore, we provide an explicit form for the state of the CTC system such that it is a maximum-entropy state, as prescribed by Deutsch.
Regionalism, Regionalization and Regional Development
Directory of Open Access Journals (Sweden)
Liviu C. Andrei
2016-03-01
Full Text Available Sustained development is a concept associating other concepts, in its turn, in the EU practice, e.g. regionalism, regionalizing and afferent policies, here including structural policies. This below text, dedicated to integration concepts, will limit on the other hand to regionalizing, otherwise an aspect typical to Europe and to the EU. On the other hand, two aspects come up to strengthen this field of ideas, i.e. the region (al-regionalism-(regional development triplet has either its own history or precise individual outline of terms.
A note on G2 log-aesthetic curves
Wo, Mei Seen; Gobithaasan R., U.; Miura, Kenjiro T.; Abbas, Muhammad
2015-12-01
Log-aesthetic curve (LAC) is a curve family composed of transcendental curves that includes logarithmic spiral, clothoid, circle involute and Nielsen's spiral. They have linear logarithmic curvature graphs (LCGs) and are highly aesthetic. In order to implement G2 LAC in industrial design successfully, one needs guidance on the existence and uniqueness whether a LAC segment satisfy given G2 Hermite data. This paper focuses shows the existence and uniqueness of solution for single segment G2 LAC. A LAC equation that incorporates both start and end curvatures, and end tangential angle is first derived. Then, the end points of the LAC segments are calculated using the derived LAC equation, which is also a representation of the solution region of LAC given a set of G2 Hermite data. The derived function is investigated for its existence and uniqueness. It is shown that the solution region is a curve that do not self-intersect anywhere, thus the solution of single segment G2 LAC is always unique.
Certified Approximation of Parametric Space Curves with Cubic B-spline Curves
Shen, Liyong; Gao, Xiao-Shan
2012-01-01
Approximating complex curves with simple parametric curves is widely used in CAGD, CG, and CNC. This paper presents an algorithm to compute a certified approximation to a given parametric space curve with cubic B-spline curves. By certified, we mean that the approximation can approximate the given curve to any given precision and preserve the geometric features of the given curve such as the topology, singular points, etc. The approximated curve is divided into segments called quasi-cubic B\\'{e}zier curve segments which have properties similar to a cubic rational B\\'{e}zier curve. And the approximate curve is naturally constructed as the associated cubic rational B\\'{e}zier curve of the control tetrahedron of a quasi-cubic curve. A novel optimization method is proposed to select proper weights in the cubic rational B\\'{e}zier curve to approximate the given curve. The error of the approximation is controlled by the size of its tetrahedron, which converges to zero by subdividing the curve segments. As an applic...
Uniform trigonometric polynomial B-spline curves
Institute of Scientific and Technical Information of China (English)
吕勇刚; 汪国昭; 杨勋年
2002-01-01
This paper presents a new kind of uniform spline curve, named trigonometric polynomialB-splines, over space Ω = span{sint, cost, tk-3,tk-4,…,t,1} of which k is an arbitrary integerlarger than or equal to 3. We show that trigonometric polynomial B-spline curves have many similarV properties to traditional B-splines. Based on the explicit representation of the curve we have also presented the subdivision formulae for this new kind of curve. Since the new spline can include both polynomial curves and trigonometric curves as special cases without rational form, it can be used as an efficient new model for geometric design in the fields of CAD/CAM.
Research on physical shape preserving curve reconstruction
Institute of Scientific and Technical Information of China (English)
TANG Kelun; ZHANG Xiangwei; CHENG Siyuan; XIONG Hanwei; ZHANG Hong
2007-01-01
Fusion of various data is an effective way to improve the precision and efficiency of acquiring information in reverse engineering.A method of physical shape preserving curve reconstruction is proposed to better realize the data fusion of coordinate measuring machine (CMM) and visual information.From the principle of materials mechanics,the strain energy of the curve corresponding to the distortion is advanced as the internal energy,and the elastic potential energy of the curve is established,using a few precise measured data points as the equilibrium position,to be the external energy.On the basis of the principle of variation calculus,the basic spline finite element method (B-spline FEM) is used to determine the equilibrium position of curve deformation.Numerical simulation indicates that there is an extremely good agreement between the new fitted curve and the actual curve.
Forces in the complex octonion curved space
Weng, Zi-Hua
2016-01-01
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 comp...
Conditionally bounding analytic ranks of elliptic curves
Bober, Jonathan W
2011-01-01
We describe a method for bounding the rank of an elliptic curve under the assumptions of the Birch and Swinnerton-Dyer conjecture and the generalized Riemann hypothesis. As an example, we compute, under these conjectures, exact upper bounds for curves which are known to have rank at least as large as 20, 21, 22, 23, and 24. For the known curve of rank at least 28, we get a bound of 30.
Riemann Boundary Value Problems for Koch Curve
Directory of Open Access Journals (Sweden)
Zhengshun Ruanand
2012-11-01
Full Text Available In this study, when L is substituted for Koch curve, Riemann boundary value problems was defined, but generally speaking, Cauchy-type integral is meaningless on Koch curve. When some analytic conditions are attached to functions G (z and g (z, through the limit function of a sequence of Cauchytype integrals, the homogeneous and non-homogeneous Riemann boundary problems on Koch curve are introduced, some similar results was attained like the classical boundary value problems for analytic functions.
Skill Acquisition Curves and Military Training
1986-01-01
group acquisition curves had one of two general shapes, either logarithmic (power function) or semi- logarithmic (exponential), including variants...is, so far as we aware, no inherent advantage to the use of equations in linear or logarithmic form other than that the display of fitted curves in...implications for the expected form of the acquisition curve . As Mazur and Hastie (1978) note, accumulation models yield the hyperbola (a power law
A Local Torelli's Theorem for SUSY curves
Codogni, Giulio
2014-01-01
SUSY curves, or super Riemann surfaces, are the generalization of Riemann surfaces in the context of super geometry. The main goal of this paper is to construct some explicit families of SUSY curves with odd moduli and compute their periods. By comparing our result with its classical analogue, we make an educated guess about the tangent space to the period domain and the differential of the Jacobian morphism for SUSY curves.
Algebraic arctic curves in the domain-wall six-vertex model
Colomo, F
2010-01-01
The arctic curve, i.e. the spatial curve separating ordered (or `frozen') and disordered (or `temperate) regions, of the six-vertex model with domain wall boundary conditions is discussed for the root-of-unity vertex weights. In these cases the curve is described by algebraic equations which can be worked out explicitly from the parametric solution for this curve. Some interesting examples are discussed in detail. The upper bound on the maximal degree of the equation in a generic root-of-unity case is obtained.
Algebraic curves and one-dimensional fields
Bogomolov, Fedor
2002-01-01
Algebraic curves have many special properties that make their study particularly rewarding. As a result, curves provide a natural introduction to algebraic geometry. In this book, the authors also bring out aspects of curves that are unique to them and emphasize connections with algebra. This text covers the essential topics in the geometry of algebraic curves, such as line and vector bundles, the Riemann-Roch Theorem, divisors, coherent sheaves, and zeroth and first cohomology groups. The authors make a point of using concrete examples and explicit methods to ensure that the style is clear an
Orthogonal Polynomials and $S$-curves
Rakhmanov, E A
2011-01-01
This paper is devoted to a study of $S$-curves, that is systems of curves in the complex plane whose equilibrium potential in a harmonic external field satisfies a special symmetry property ($S$-property). Such curves have many applications. In particular, they play a fundamental role in the theory of complex (non-hermitian) orthogonal polynomials. One of the main theorems on zero distribution of such polynomials asserts that the limit zero distribution is presented by an equilibrium measure of an $S$-curve associated with the problem if such a curve exists. These curves are also the starting point of the matrix Riemann-Hilbert approach to srtong asymptotics. Other approaches to the problem of strong asymptotics (differential equations, Riemann surfaces) are also related to $S$-curves or may be interpreted this way. Existence problem $S$-curve in a given class of curves in presence of a nontrivial external field presents certain challenge. We formulate and prove a version of existence theorem for the case whe...
Flat Galactic Rotation Curves from Geometry in Weyl Gravity
Deliduman, Cemsinan; Yapiskan, Baris
2015-01-01
We searched a resolution of the flat galactic rotation curve problem from geometry instead of assuming the existence of dark matter. We observed that the scale independence of the rotational velocity in the outer region of galaxies could point out to a possible existence of local scale symmetry and therefore the gravitational phenomena inside such regions should be described by the unique local scale symmetric theory, namely Weyl's theory of gravity. We solved field equations of Weyl gravity and determined the special geometry of the outer region of galaxies. In order to understand the scale dependent description of gravitational phenomena, we compared individual terms of so called Einstein-Weyl theory and conjectured that while the outer region of galaxies are described by the Weyl term, the inner region of galaxies are described by the Einstein-Hilbert term.
Institute of Scientific and Technical Information of China (English)
王世宏
2008-01-01
Objective To detect the curve of ventricular wall motion features of regional wall abnor-malities in patients with coronary artery disease during each diastolic period, and its possibility to evaluate re-gional left ventricular diastolic function. Methods Fifty-four patients with anterior myocardial infarction (MI group) and 78 normal subjects (NOR group) underwent Doppler tissue imaging, which were performed in 2-chamber-view by the tracing technology of ventrieular wall motion synchronously. Isovolumic relax-ation period, rapid flow period, slow filling phase, atrial systole period were measured. Results In NOR group, distant value of 76 patients (97.44%) showed a gradually decreasing positive value from the apex to middle and from middle to base of left ventricle. While in MI group, such rules disappeared, 52 patients (96.30%) were negative in infarction area. In isevolumic relaxation period in NOR group, 76 patients (97.44%) showed palliative downward wave, but in MI group, 27 patients (50.00%) showed palliative downward wave(P<0.05). In rapid flow period, both NOR and MI group showed downward and steep waves,but in MI group, the gradient rule disappeared and distance of ventricular wall motion was negative in infarc-tion area. In slow filling phase, compared with NOR group, which had horizontal wave, MI group had no obvi-ously horizontal waves. Conclusion Regional myocardial ischemia and infarction can cause significant ab-normalities of regional ventricular wall motion in active diastolic phase, and it can be evaluated quantitatively and synchronously with high sensitivity by the curve of ventricular wall motion which has the potential value in regional left ventricular diastolic function.%目的 探讨冠心病患者左心室舒张各期局部心肌运动幅度曲线特点及其评价左心室局域舒张功能的可能性.方法 对54例前壁心肌梗死患者(MI组)和78例健康对照者(NOR组)左心室心肌进行组织多普勒成像检查.记录心
Construction of Endpoint Constrained Cubic Rational Curve with Chord-Length Parameterization
Institute of Scientific and Technical Information of China (English)
LI Pei-pei; ZHANG Xin; ZHANG Ai-wu
2013-01-01
This paper discusses the problem that constructing a curve to satisfy the given endpoint constraints and chord-length parameters. Based on the research of Lu, the curve construction method for the entire tangent angles region 0 1(α,α)∈(-π,π) × (-π,π) is given. Firstly, to ensure the weights are always positive, the three characteristics of cubic rational Bezier curve is proved, then the segment construction idea for the other tangent angles are presented in view of the three characteristics. The curve constructed with the new method satisfies the endpoint constraint and chord-length parameters, it’s G1 continuous in every segment curve, and the shapes of the curve are well.
The Impact of the Combination of Circular Curve and Transition Curve on Highway Operation Security
Directory of Open Access Journals (Sweden)
Cao Youlu
2015-07-01
Full Text Available By investigating the accident in 2009 and 2011 of Taijiu Expressway, the study analyzed the relationship between the horizontal curve radiuses, the length of horizontal curve, the length of transition curve and the number of accidents, established the corresponding regression model. The trend of accidents was determined with different length of transition curve and different combination of circular curve according to this model. The results show that the circular curve radius and length of transition curve increase with the decreases of accidents number, the number of accidents decreases with the increase of the ratio of the length of the transition curve and the length of the round curve. When the ratio of the parameters of the transition curve and the radius of the circle is between 0.3-0.6, the accidents are more focused. The bigger change rate of curves is, there are more accidents of flat curve. To evaluate road traffic safety from the perspective of horizontal curve alignment design, these regularities have very important reference.
Learning curves in energy planning models
Energy Technology Data Exchange (ETDEWEB)
Barreto, L.; Kypreos, S. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)
1999-08-01
This study describes the endogenous representation of investment cost learning curves into the MARKAL energy planning model. A piece-wise representation of the learning curves is implemented using Mixed Integer Programming. The approach is briefly described and some results are presented. (author) 3 figs., 5 refs.
Curve Matching with Applications in Medical Imaging
DEFF Research Database (Denmark)
Bauer, Martin; Bruveris, Martins; Harms, Philipp
2015-01-01
In the recent years, Riemannian shape analysis of curves and surfaces has found several applications in medical image analysis. In this paper we present a numerical discretization of second order Sobolev metrics on the space of regular curves in Euclidean space. This class of metrics has several...
Rotation curve of the Milky Way
Directory of Open Access Journals (Sweden)
Lee Y.S.
2012-02-01
Full Text Available We use SEGUE and Hipparcos data to restrict the behaviour of the rotation curve of the Milky Way in the solar neighbourhood. Then we construct a density model of the Milky Way which best reproduces the available observations of the rotation curve and is consistent with the density constraints in the solar neighbourhood.
Spectral Curves of Operators with Elliptic Coefficients
Directory of Open Access Journals (Sweden)
J. Chris Eilbeck
2007-03-01
Full Text Available A computer-algebra aided method is carried out, for determining geometric objects associated to differential operators that satisfy the elliptic ansatz. This results in examples of Lamé curves with double reduction and in the explicit reduction of the theta function of a Halphen curve.
Tautological Integrals on Symmetric Products of Curves
Institute of Scientific and Technical Information of China (English)
Zhi Lan WANG
2016-01-01
We propose a conjecture on the generating series of Chern numbers of tautological bundles on symmetric products of curves and establish the rank 1 and rank −1 case of this conjecture. Thus we compute explicitly the generating series of integrals of Segre classes of tautological bundles of line bundles on curves, which has a similar structure as Lehn’s conjecture for surfaces.
Green's Conjecture for the generic canonical curve
Teixidor-I-Bigas, Montserrat
1998-01-01
Green's Conjecture states the following : syzygies of the canonical model of a curve are simple up to the p^th stage if and only if the Clifford index of C is greater than p. We prove that the generic curve of genus g satisfies Green's conjecture.
Blending Canal Surfaces Based on PH Curves
Institute of Scientific and Technical Information of China (English)
Chen-Dong Xu; Fa-Lai Chen
2005-01-01
In this paper, a new method for blending two canal surfaces is proposed. The blending surface is itself a generalized canal surface, the spine curve of which is a PH (Pythagorean-Hodograph) curve. The blending surface possesses an attractive property - its representation is rational. The method is extensible to blend general surfaces as long as the blending boundaries are well-defined.
The density curve of F distribution
Institute of Scientific and Technical Information of China (English)
LIU Xiaopeng; LIU Kunhui
2004-01-01
Employing the properties of special function,we discuss the positional relation between two density curves with different parameters for F distribution in this paper.Some varying regularities about the position of density curve of F distribution have been obtained.
Electrical-Discharge Machining Of Curved Passages
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.
Integrability and the motion of curves
Nakayama, Kazuaki; Segur, Harvey; Wadati, Miki
1992-11-01
Recently discovered connections between integrable evolution equations and the motion of curves are based on the following fact: The Serret-Frenet equations are equivalent to the Ablowitz-Kaup-Newell-Segur (AKNS) scattering problem at zero eigenvalue. This equivalence identifies those evolution equations, integrable or not, that can describe the motion of curves.
Constructing forward price curves in electricity markets
DEFF Research Database (Denmark)
Fleten, S.-E.; Lemming, Jørgen Kjærgaard
2003-01-01
We present and analyze a method for constructing approximated high-resolution forward price curves in electricity markets. Because a limited number of forward or futures contracts are traded in the market, only a limited picture of the theoretical continuous forward price curve is available...
47 CFR 80.767 - Propagation curve.
2010-10-01
... 47 Telecommunication 5 2010-10-01 2010-10-01 false Propagation curve. 80.767 Section 80.767... MARITIME SERVICES Standards for Computing Public Coast Station VHF Coverage § 80.767 Propagation curve. The propagation graph, § 80.767 Graph 1, must be used in computing the service area contour. The graph...
Measuring Model Rocket Engine Thrust Curves
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…
Modeling Start Curves of Bainite Formation
Van Bohemen, S.M.C.
2009-01-01
It is demonstrated that calculations with a physically based model give an accurate description of the start curve of bainite formation in a wide range of steels. The temperature dependence of the overall kinetics, which determines the characteristic C shape of the start curve, is controlled by both
Measuring Model Rocket Engine Thrust Curves
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…
Estimates for J-curves as submanifolds
Fish, Joel W
2009-01-01
Here we develop some basic analytic tools to study compactness properties of $J$-curves (i.e. pseudo-holomorphic curves) when regarded as submanifolds. Incorporating techniques from the theory of minimal surfaces, we derive an inhomogeneous mean curvature equation for such curves, we establish an extrinsic monotonicity principle for non-negative functions $f$ satisfying $\\Delta f\\geq -c^2 f$, we show that curves locally parameterized as a graph over a coordinate tangent plane have all derivatives a priori bounded in terms of curvature and ambient geometry, and we establish $\\epsilon$-regularity for the square length of their second fundamental forms. These results are all provided for $J$-curves either with or without Lagrangian boundary and hold in almost Hermitian manifolds of arbitrary even dimension (i.e. Riemannian manifolds for which the almost complex structure is an isometry).
STATIONARY CONNECTED CURVES IN HILBERT SPACES
Directory of Open Access Journals (Sweden)
Raed Hatamleh
2014-01-01
Full Text Available In this article the structure of non-stationary curves which are stationary connected in Hilbert space is studied using triangular models of non-self-adjoint operator. The concept of evolutionary representability plays here an important role. It is proved that if one of two curves in Hilbert space is evolutionary representable and the curves are stationary connected, then another curve is evolutionary representable too. These curves are studied firstly. The structure of a cross-correlation function in the case when operator, defining the evolutionary representation, has one-dimensional non-Hermitian subspace (the spectrum is discreet and situated in the upper complex half-plane or has infinite multiplicity at zero (Volterra operator is studied.
Generating artificial light curves: Revisited and updated
Emmanoulopoulos, D; Papadakis, I E
2013-01-01
The production of artificial light curves with known statistical and variability properties is of great importance in astrophysics. Consolidating the confidence levels during cross-correlation studies, understanding the artefacts induced by sampling irregularities, establishing detection limits for future observatories are just some of the applications of simulated data sets. Currently, the widely used methodology of amplitude and phase randomisation is able to produce artificial light curves which have a given underlying power spectral density (PSD) but which are strictly Gaussian distributed. This restriction is a significant limitation, since the majority of the light curves e.g. active galactic nuclei, X-ray binaries, gamma-ray bursts show strong deviations from Gaussianity exhibiting `burst-like' events in their light curves yielding long-tailed probability distribution functions (PDFs). In this study we propose a simple method which is able to precisely reproduce light curves which match both the PSD an...
Remote sensing used for power curves
Wagner, R.; Jørgensen, H. E.; Paulsen, U. S.; Larsen, T. J.; Antoniou, I.; Thesbjerg, L.
2008-05-01
: Power curve measurement for large wind turbines requires taking into account more parameters than only the wind speed at hub height. Based on results from aerodynamic simulations, an equivalent wind speed taking the wind shear into account was defined and found to reduce the power standard deviation in the power curve significantly. Two LiDARs and a SoDAR are used to measure the wind profile in front of a wind turbine. These profiles are used to calculate the equivalent wind speed. The comparison of the power curves obtained with the three instruments to the traditional power curve, obtained using a cup anemometer measurement, confirms the results obtained from the simulations. Using LiDAR profiles reduces the error in power curve measurement, when these are used as relative instrument together with a cup anemometer. Results from the SoDAR do not show such promising results, probably because of noisy measurements resulting in distorted profiles.
Curved and conformal high-pressure vessel
Energy Technology Data Exchange (ETDEWEB)
Croteau, Paul F.; Kuczek, Andrzej E.; Zhao, Wenping
2016-10-25
A high-pressure vessel is provided. The high-pressure vessel may comprise a first chamber defined at least partially by a first wall, and a second chamber defined at least partially by the first wall. The first chamber and the second chamber may form a curved contour of the high-pressure vessel. A modular tank assembly is also provided, and may comprise a first mid tube having a convex geometry. The first mid tube may be defined by a first inner wall, a curved wall extending from the first inner wall, and a second inner wall extending from the curved wall. The first inner wall may be disposed at an angle relative to the second inner wall. The first mid tube may further be defined by a short curved wall opposite the curved wall and extending from the second inner wall to the first inner wall.
AHT Bézier Curves and NUAHT B-Spline Curves
Institute of Scientific and Technical Information of China (English)
Gang Xu; Guo-Zhao Wang
2007-01-01
In this paper, we present two new unified mathematics models of conics and polynomial curves, called algebraic hyperbolic trigonometric ( AHT) Bézier curves and non-uniform algebraic hyperbolic trigonometric ( NUAHT) B-sptine curves of order n, which are generated over the space span{sin t, cos t, sinh t, cosh t, 1, t,..., tn-5}, n ≥ 5. The two kinds of curves share most of the properties as those of the Bézier curves and B-spline curves in polynomial space. In particular, they can represent exactly some remarkable transcendental curves such as the helix, the cycloid and the catenary. The subdivision formulae of these new kinds of curves are also given. The generations of the tensor product surfaces are straightforward. Using the new mathematics models, we present the control mesh representations of two classes of minimal surfaces.
Expression, crosslinking, and developing modulus master curves of recombinant resilin.
Khandaker, Md Shahriar K; Dudek, Daniel M; Beers, Eric P; Dillard, David A
2017-05-01
Resilin is a disordered elastomeric protein found in specialized regions of insect cuticles, where low stiffness and high resilience are required. Having a wide range of functions that vary among insect species, resilin operates across a wide frequency range, from 5Hz for locomotion to 13kHz for sound production. We synthesize and crosslink a recombinant resilin from clone-1 (exon-1+exon-2) of the gene, and determine the water content (approximately 80wt%) and dynamic mechanical properties, along with estimating surface energies relevant for adhesion. Dynamic moduli master curves have been developed, by applying the time-temperature superposition principle (TTSP) and time-temperature concentration superposition principle (TTCSP), and compared with reported master curves for natural resilin from locusts, dragonflies, and cockroaches. To our knowledge, this is the first time dynamic moduli master curves have been developed to explore the dynamic mechanical properties of recombinant resilin and compare with resilin behavior. The resulting master curves show that the synthetic resilin undergoes a pronounced transition with increasing ethanol concentrations, with the storage modulus increasing by approximately three orders of magnitude. Although possibly a glass transition, alternate explanations include the formation of intramolecular hydrogen bonds or that the chitin binding domain (ChBD) in exon-2 might change the secondary structure of the normally disordered exon-1 into more ordered conformations that limit deformation.
Saturation curves of parallel-plate ionization chambers
Energy Technology Data Exchange (ETDEWEB)
Fallone, B.G.; Podgorsak, E.B.
A new analytical expression is presented to describe the full saturation curve of parallel-plate ionization chambers. In contrast to the presently known expressions, which hold only for the near saturation region, this empirically determined expression is in excellent agreement with measurements in the whole collection efficiency range from 0 to 1 for x-ray sources with effective energies from 20 to 150 keV and cobalt-60 gamma rays. The dependence of the ion collection efficiency and the extrapolated electric field, which is a parameter in the new saturation curve expression, on electric field, dose, dose rate, beam quality, and chamber volume, is discussed. The effect of photoemission from the chamber polarizing electrode for low-energy x-ray beams on the saturation current is demonstrated. A universal ionization chamber constant is derived experimentally. It is shown that all parameters of the saturation curve equation and thus the saturation curve itself, can be calculated from one single measurement of ionization current at a given electric field and air gap thickness.
NEW ULTRAVIOLET EXTINCTION CURVES FOR INTERSTELLAR DUST IN M31
Energy Technology Data Exchange (ETDEWEB)
Clayton, Geoffrey C. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Gordon, Karl D.; Bohlin, R. C. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bianchi, Luciana C. [Department of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218 (United States); Massa, Derck L.; Wolff, Michael J. [Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 (United States); Fitzpatrick, Edward L., E-mail: gclayton@fenway.phys.lsu.edu, E-mail: bohlin@stsci.edu, E-mail: kgordon@stsci.edu, E-mail: bianchi@jhu.edu, E-mail: mjwolff@spacescience.org, E-mail: edward.fitzpatrick@villanova.edu [Department of Astronomy and Astrophysics, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085 (United States)
2015-12-10
New low-resolution UV spectra of a sample of reddened OB stars in M31 were obtained with the Hubble Space Telescope/STIS to study the wavelength dependence of interstellar extinction and the nature of the underlying dust grain populations. Extinction curves were constructed for four reddened sightlines in M31 paired with closely matching stellar atmosphere models. The new curves have a much higher signal-to-noise ratio than previous studies. Direct measurements of N(H i) were made using the Lyα absorption lines enabling gas-to-dust ratios to be calculated. The sightlines have a range in galactocentric distance of 5–14 kpc and represent dust from regions of different metallicities and gas-to-dust ratios. The metallicities sampled range from solar to 1.5 solar. The measured curves show similarity to those seen in the Milky Way and the Large Magellanic Cloud. The Maximum Entropy Method was used to investigate the dust composition and size distribution for the sightlines observed in this program, finding that the extinction curves can be produced with the available carbon and silicon abundances if the metallicity is super-solar.
Testing MONDian dark matter with galactic rotation curves
Energy Technology Data Exchange (ETDEWEB)
Edmonds, Doug [Department of Physics, Emory and Henry College, Emory, VA 24327 (United States); Farrah, Duncan; Minic, Djordje; Takeuchi, Tatsu [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Ho, Chiu Man [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Ng, Y. Jack, E-mail: dedmonds@ehc.edu, E-mail: farrah@vt.edu, E-mail: dminic@vt.edu, E-mail: takeuchi@vt.edu, E-mail: chiuman.ho@vanderbilt.edu, E-mail: yjng@physics.unc.edu [Institute of Field Physics, Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599 (United States)
2014-09-20
MONDian dark matter (MDM) is a new form of dark matter quantum that naturally accounts for Milgrom's scaling, usually associated with modified Newtonian dynamics (MOND), and theoretically behaves like cold dark matter (CDM) at cluster and cosmic scales. In this paper, we provide the first observational test of MDM by fitting rotation curves to a sample of 30 local spiral galaxies (z ≈ 0.003). For comparison, we also fit the galactic rotation curves using MOND and CDM. We find that all three models fit the data well. The rotation curves predicted by MDM and MOND are virtually indistinguishable over the range of observed radii (∼1 to 30 kpc). The best-fit MDM and CDM density profiles are compared. We also compare with MDM the dark matter density profiles arising from MOND if Milgrom's formula is interpreted as Newtonian gravity with an extra source term instead of as a modification of inertia. We find that discrepancies between MDM and MOND will occur near the center of a typical spiral galaxy. In these regions, instead of continuing to rise sharply, the MDM mass density turns over and drops as we approach the center of the galaxy. Our results show that MDM, which restricts the nature of the dark matter quantum by accounting for Milgrom's scaling, accurately reproduces observed rotation curves.
New Ultraviolet Extinction Curves for Interstellar Dust in M31
Clayton, Geoffrey C; Bianchi, Luciana C; Massa, Derck L; Fitzpatrick, Edward L; Bohlin, R C; Wolff, Michael J
2015-01-01
New low-resolution UV spectra of a sample of reddened OB stars in M31 were obtained with HST/STIS to study the wavelength dependence of interstellar extinction and the nature of the underlying dust grain populations. Extinction curves were constructed for four reddened sightlines in M31 paired with closely matching stellar atmosphere models. The new curves have a much higher S/N than previous studies. Direct measurements of N(H I) were made using the Ly$\\alpha$ absorption lines enabling gas-to-dust ratios to be calculated. The sightlines have a range in galactocentric distance of 5 to 14 kpc and represent dust from regions of different metallicities and gas-to-dust ratios. The metallicities sampled range from Solar to 1.5 Solar. The measured curves show similarity to those seen in the Milky Way and the Large Magellanic Cloud. The Maximum Entropy Method was used to investigate the dust composition and size distribution for the sightlines observed in this program finding that the extinction curves can be produc...
Unifying representation of Bézier curve and two kinds of generalized ball curves
Institute of Scientific and Technical Information of China (English)
ZHU Xiaolin; WANG Zhihua
2012-01-01
This paper presents a new basis, the WSB basis, which unifies the Bemstein basis, Wang-Ball basis and Said-Ball basis, and therefore the Bézier curve, Wang-Ball curve and Said-Ball curve are the special cases of the WSB curve based on the WSB basis In addition, the relative degree elevation formula, recursive algorithm and conversion formula between the WSB basis and the Bern- stein basis are given.
Institute of Scientific and Technical Information of China (English)
Xu Guangyue; Song Deyong
2011-01-01
Based on the Environmental Kuznets Curve theory, the authors choose provincial panel data of China in 1990-2007 and adopt panel trait root and co-integration testing method to study whether there is Environmental Kuznets Curve for China＇s carbon emissions. The research results show that： carbon emissions per capita of the eastern region and the central region of China fit into Environmental Kuznets Curve, but that of the western region does not. On this basis, the authors carry out scenario analysis on the occurrence time of the inflection point of carbon emissions per capita of different regions, and describe a specific time path.
Three-body choreographies in given curves
Energy Technology Data Exchange (ETDEWEB)
Ozaki, Hiroshi [General Education Program Center, Tokai University, 317 Nishino, Numazu, Shizuoka 410-0395 (Japan); Fukuda, Hiroshi; Fujiwara, Toshiaki [College of Liberal Arts and Sciences, Kitasato University, 1-15-1 Kitasato, Sagamihara, Kanagawa 228-8555 (Japan)], E-mail: ozaki@keyaki.cc.u-tokai.ac.jp, E-mail: fukuda@kitasato-u.ac.jp, E-mail: fujiwara@kitasato-u.ac.jp
2009-10-02
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.
Investigation of learning and experience curves
Energy Technology Data Exchange (ETDEWEB)
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.
Melting curves of metals by ab initio calculations
Minakov, Dmitry; Levashov, Pavel
2015-06-01
In this work we used several ab initio approaches to reproduce melting curves and discussed their abilities, advantages and drawbacks. We used quasiharmonic appoximation and Lindemann criterion to build melting curves in wide region of pressures. This approach allows to calculate the total free energy of electrons and phonons, so it is possible to obtain all thermodynamic properties in the crystalline state. We also used quantum molecular dynamics simulations to investigate melting at various pressures. We explored the size-effect of the heat until it melts (HUM) method in detail. Special attention was paid to resolve the boundaries of the melting region on density. All calculations were performed for aluminum, copper and gold. Results were in good agreement with available experimental data. Also we studied the influence of electronic temperature on melting curves. It turned out that the melting temperature increased with the rise of electron temperature at normal density and had non-monotonic behavior at higher densities. This work is supported by the Ministry of Education and Science of the Russian Federation (Project No. 3.522.2014/K).
Reactor Network Synthesis Based on Instantaneous Objective Function Characteristic Curves
Institute of Scientific and Technical Information of China (English)
张治山; 赵文; 王艳丽; 周传光; 袁希钢
2003-01-01
It is believed that whether the instantaneous objective function curves of plug-flow-reactor (PFR) and continuous-stirred-tank-reactor (CSTR) overlap or not, they have a consistent changing trend for complex reactions(steady state, isothermal and constant volume). As a result of the relation of the objective functions (selectivity or yield) to the instantaneous objective functions (instantaneous selectivity or instantaneous reaction rate), the optimal reactor network configuration can be determined according to the changing trend of the instantaneous objective function curves. Further, a recent partition strategy for the reactor network synthesis based on the instantaneous objective function characteristic curves is proposed by extending the attainable region partition strategy from the concentration space to the instantaneous objective function-unreacted fraction of key reactant space. In this paper,the instantaneous objective function is closed to be the instantaneous selectivity and several samples axe examined to illustrate the proposed method. The comparison with the previous work indicates it is a very convenient and practical systematic tool of the reactor network synthesis and seems also promising for overcoming the dimension limit of the attainable region partition strategy in the concentration space.
Order and Jamming on Curved Surfaces
Burke, Christopher J.
Geometric frustration occurs when a physical system's preferred ordering (e.g. spherical particles packing in a hexagonal lattice) is incompatible with the system's geometry. An example of this occurs in arrested relaxation in Pickering emulsions. Pickering emulsions are emulsions (e.g. mixtures of oil and water) with colloidal particles mixed in. The particles tend to lie at an oil-water interface, and can coat the surface of droplets within the emulsion (e.g. an oil droplet surrounded by water.) If a droplet is deformed from its spherical ground state, more particles adsorb at the surface, and the droplet is allowed to relax, then the particles on the surface can become close packed and prevent further relaxation, arresting the droplet in a non-spherical shape. The resulting structures tend to be relatively well ordered with regions of highly hexagonal packings; however, the curvature of the surface prevents perfect ordering and defects in the packing are required. These defects may influence the stability of these structures, making it important to understand how to predict and control them for applications in the food, cosmetic, oil, and medical industries. In this work, we use simulations to study the ordering and stability of sphere packings on arrested emulsions droplets. We first isolate the role of surface geometry by creating packings on a static ellipsoidal surface. Next we perform simulations which include dynamic effects that are present in the experimental Pickering emulsion system. Packings are created by evolving an ellipsoidal surface towards a spherical shape at fixed volume; the effects of relaxation rate, interparticle attraction, and gravity are determined. Finally, we study jamming on curved surfaces. Packings of hard particles are used to study marginally stable packings and the role curvature plays in constraining them. We also study packings of soft particles, compressed beyond marginal stability, and find that geometric frustration plays
Supersonic Flutter of Laminated Curved Panels
Directory of Open Access Journals (Sweden)
M. Ganapathi
1995-04-01
Full Text Available Supersonic flutter analysis of laminated composite curved panels is investigated using doubly-curved, quadrilateral, shear flexible, shell element based on field-consistency approach. The formulation includes transverse shear deformation, in-plane and rotary inertias. The aerodynamic force is evaluated using two-dimensional static aerodynamic approximation for high supersonic flow. Initially, the model developed here is verified for the flutter analysis of flat plates. Numerical results are presented for isotropic, orthotropic and laminated anisotropic curved panels. A detailed parametric study is carried out to observe the effects of aspect and thickness ratios, number of layers, lamination scheme, and boundary conditions on flutter boundary.
Mapping curved spacetimes into Dirac spinors
Sabín, Carlos
2016-01-01
We show how to transform a Dirac equation in curved spacetime into a Dirac equation in flat spacetime. In particular, we show that any solution of the free massless Dirac equation in a 1+1 dimensional flat spacetime can be transformed via a local phase transformation into a solution of the corresponding Dirac equation in a curved background, where the spacetime metric is encoded into the phase. In this way, the existing quantum simulators of the Dirac equation can naturally incorporate curved spacetimes. As a first example we use our technique to obtain solutions of the Dirac equation in a particular family of interesting spacetimes in 1+1 dimensions.
Magnetization curve modelling of soft magnetic alloys
Energy Technology Data Exchange (ETDEWEB)
Meszaros, I, E-mail: meszaros@eik.bme.hu [Department of Materials Science and Engineering, Budapest University of Technology and Economics, Bertalan L. street 7., Budapest, H-1111 (Hungary)
2011-01-01
In this paper we present an application of the so called hyperbolic model of magnetization. The model was modified and it was applied for nine different soft magnetic alloys. The tested samples were electro-technical steels (FeSi alloys) and a permalloy (FeNi alloy) with strongly different magnetic properties. Among them there are top, medium and definitely poor quality soft magnetic materials as well. Their minor hysteresis loops and normal magnetization curves were measured by alternating current measurement. The hyperbolic model of magnetization was applied for the experimental normal magnetization curves. It was proved that the applied model is excellent for describing mathematically the experimental magnetization curves.
CRC standard curves and surfaces with Mathematica
von Seggern, David H
2006-01-01
Since the publication of the first edition, Mathematica® has matured considerably and the computing power of desktop computers has increased greatly. This enables the presentation of more complex curves and surfaces as well as the efficient computation of formerly prohibitive graphical plots. Incorporating both of these aspects, CRC Standard Curves and Surfaces with Mathematica®, Second Edition is a virtual encyclopedia of curves and functions that depicts nearly all of the standard mathematical functions rendered using Mathematica. While the easy-to-use format remains unchanged from the previ
Curves and surfaces in the context of optometry. Part 1: Curves*
2005-01-01
This paper introduces the differential geom-etry of curves in Euclidean 3-space, the motiva-tion being the writer’s belief that, despite their fundamental importance, curves are inadequate-ly treated in optometric educational programs. Curvature and torsion are defined along a curve. Two numerical examples are presented. The fundamental theorem of curves is stated. The relationship of the geometry of varifocal lenses and curves known as involutes are discussed. A brief treatment of the t...
Orbital Signatures from Observed Light Curves of Blazars
Indian Academy of Sciences (India)
A. Mangalam; P. Mohan
2014-09-01
Variability in active galactic nuclei is observed in UV to X-ray emission based light curves. This could be attributed to orbital signatures of the plasma that constitutes the accretion flow on the putative disk or in the developing jet close to the inner region of the central black hole. We discuss some theoretical models based on this view. These models include general relativistic effects such as light bending, aberration effects, gravitational and Doppler redshifts. The novel aspects relate to the treatment of helical flow in cylindrical and conical geometries in the vicinity of a Schwarzschild black hole that leads to amplitude and frequency modulations of simulated light curves as well as the inclusion of beaming effects in these idealized geometries. We then present a suite of time series analysis techniques applicable to data with varied properties which can extract detailed information for their use in theoretical models.
Feature curve extraction from point clouds via developable strip intersection
Directory of Open Access Journals (Sweden)
Kai Wah Lee
2016-04-01
Full Text Available In this paper, we study the problem of computing smooth feature curves from CAD type point clouds models. The proposed method reconstructs feature curves from the intersections of developable strip pairs which approximate the regions along both sides of the features. The generation of developable surfaces is based on a linear approximation of the given point cloud through a variational shape approximation approach. A line segment sequencing algorithm is proposed for collecting feature line segments into different feature sequences as well as sequential groups of data points. A developable surface approximation procedure is employed to refine incident approximation planes of data points into developable strips. Some experimental results are included to demonstrate the performance of the proposed method.
Trapping and guiding surface plasmons in curved graphene landscapes
Smirnova, Daria; Wang, Zheng; Kivshar, Yuri S; Khanikaev, Alexander B
2015-01-01
We demonstrate that graphene placed on top of structured substrates offers a novel approach for trapping and guiding surface plasmons. A monolayer graphene with a spatially varying curvature exhibits an effective trapping potential for graphene plasmons near curved areas such as bumps, humps and wells. We derive the governing equation for describing such localized channel plasmons guided by curved graphene and validate our theory by the first-principle numerical simulations. The proposed confinement mechanism enables plasmon guiding by the regions of maximal curvature, and it offers a versatile platform for manipulating light in planar landscapes. In addition, isolated deformations of graphene such as bumps are shown to support localized surface modes and resonances suggesting a new way to engineer plasmonic metasurfaces.
Simulated Performance of Timescale Metrics for Aperiodic Light Curves
Findeisen, Krzysztof; Hillenbrand, Lynne
2014-01-01
Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time domain surveys, it is increasingly essential to develop methods to quantify and analyze aperiodic variability. We develop three timescale metrics that have been little used in astronomy -- {\\Delta}m-{\\Delta}t plots, peak-finding, and Gaussian process regression -- and present simulations comparing their effectiveness across a range of aperiodic light curve shapes, characteristic timescales, observing cadences, and signal to noise ratios. We find that Gaussian process regression is easily confused by noise and by irregular sampling, even when the model being fit reflects the process underlying the light curve, but that {\\Delta}m-{\\Delta}t plots and peak-finding can coarsely characterize timescales across a broad region of parameter space. We make public the software we used for our simulations, both in the spirit of open research and to allow others to carry out ana...
Quantum Curves and $D$-Modules
Dijkgraaf, Robbert; Sulkowski, Piotr
2009-01-01
In this article we continue our study of chiral fermions on a quantum curve. This system is embedded in string theory as an I-brane configuration, which consists of D4 and D6-branes intersecting along a holomorphic curve in a complex surface, together with a B-field. Mathematically, it is described by a holonomic D-module. Here we focus on spectral curves, which play a prominant role in the theory of (quantum) integrable hierarchies. We show how to associate a quantum state to the I-brane system, and subsequently how to compute quantum invariants. As a first example, this yields an insightful formulation of (double scaled as well as general Hermitian) matrix models. Secondly, our formalism elegantly reconstructs the complete dual Nekrasov-Okounkov partition function from a quantum Seiberg-Witten curve.
Quantum curves and Script D-modules
Dijkgraaf, Robbert; Hollands, Lotte; Sułkowski, Piotr
2009-11-01
In this article we continue our study of chiral fermions on a quantum curve. This system is embedded in string theory as an I-brane configuration, which consists of D4 and D6-branes intersecting along a holomorphic curve in a complex surface, together with a B-field. Mathematically, it is described by a holonomic Script D-module. Here we focus on spectral curves, which play a prominent role in the theory of (quantum) integrable hierarchies. We show how to associate a quantum state to the I-brane system, and subsequently how to compute quantum invariants. As a first example, this yields an insightful formulation of (double scaled as well as general Hermitian) matrix models. Secondly, we formulate c = 1 string theory in this language. Finally, our formalism elegantly reconstructs the complete dual Nekrasov-Okounkov partition function from a quantum Seiberg-Witten curve.
Holomorphic Cartan geometries and rational curves
Biswas, Indranil
2010-01-01
We prove that any compact K\\"ahler manifold bearing a holomorphic Cartan geometry contains a rational curve just when the Cartan geometry is inherited from a holomorphic Cartan geometry on a lower dimensional compact K\\"ahler manifold.
Transmission of wave energy in curved ducts
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.
Halpha rotation curves the soft core question
Marchesini, D; Chincarini, G L; Firmani, C; Conconi, P; Molinari, E; Zacchei, A
2002-01-01
We present good resolution Halpha rotation curves of 6 galaxies: late-type dwarf and low surface brightness galaxies (LSB) for which accurate HI rotation curves are available from the literature. Observations are carried out at Telescopio Nazionale Galileo (TNG). For LSB F583-1 an innovative dispersing element was used, the Volume Phase Holographic (VPH) with a dispersion of about 0.35 A pxl^{-1}. From our analysis we find good agreement between the Halpha data and the HI observations concluding that the HI data for these galaxies suffer very little from beam smearing. We show that the optical rotation curves of these dark matter dominated galaxies are best fitted by the Burkert profile. In the center of galaxies, where the N-body simulations predict cusp cores and fast rising rotation curves, our data seem to be in better agreement with the presence of soft cores.
Twisted Vector Bundles on Pointed Nodal Curves
Indian Academy of Sciences (India)
Ivan Kausz
2005-05-01
Motivated by the quest for a good compactification of the moduli space of -bundles on a nodal curve we establish a striking relationship between Abramovich’s and Vistoli’s twisted bundles and Gieseker vector bundles.
Automorphisms of double coverings of curves
Torres, F
1994-01-01
We study automorphisms of curves that commute with each other. We prove that the order and the number of fixed points of one of them satisfy certain relations involving those of the other. Then, we specialize our results to the case of double coverings of curves. For instance, if the genus of the curve is at least 4\\gamma+2 and \\gamma \\geqq 1 (\\gamma = the genus of the covered curve) we prove that the order of an automorphism is bounded above by 2\\gamma+1 (resp. 4\\gamma+2) provided it is prime (resp. it has at least five fixed points). We also improve Farkas' bound on the number of fixed points namely 4\\gamma+4 by showing that it involves the order of the automorphism except in the case of even order when such an improvement is obtained provided the automorphism and the \\gamma-involution has at least one common fixed point.
ARC Code TI: ROC Curve Code Augmentation
National Aeronautics and Space Administration — ROC (Receiver Operating Characteristic) curve Code Augmentation was written by Rodney Martin and John Stutz at NASA Ames Research Center and is a modification of ROC...
KAIT Fermi AGN Light-Curve Reservoir
National Aeronautics and Space Administration — This web page shows the light curves of a total of 163 AGNs that are monitored by KAIT with average cadence of 3 days. These are unfiltered observations; in...
Bounded Population Growth: A Curve Fitting Lesson.
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)
Rational Curves on Calabi-Yau Threefolds
Katz, S
1992-01-01
The point is to compare the mathematical meaning of the ``number of rational curves on a Calabi-Yau threefold'' to the meaning ascribed to the same notion by string theorists. By considering mirror symmetry applied to conformal field theories corresponding to strings propagating in quintic hypersurfaces in projective 4-space, Candelas, de la Ossa, Green and Parkes calculated the ``number of rational curves on the hypersurface'' by comparing three point functions. Actually, the number of curves may be infinite for special examples; what is really being calculated is a path integral. The point of this talk is to give mathematical techniques and examples for computing the finite number that ``should'' correspond to an infinite family of curves (which coincides with that given by the path integral in every known instance), and to suggest that these techniques should provide the answer to the not yet solved problem of how to calculate instanton corrections to the three point function in general.
Contracts, Phillips Curve and Monetary Policy
Directory of Open Access Journals (Sweden)
Félix Jiménez
2016-02-01
Full Text Available This paper shows how to obtain a short run aggregate supply curve when there are explicit orimplicit contracts. In the same way it is possible to obtain an expectation augmented Phillips curve. Then, a monetary policy is incorporated to the short run aggregate supply curve or to the Phillips curve in order to model the Central Bank reaction when the actual inflation deviates from the target inflation. Then a model with a Central Bank welfare lost function is developed in order to obtain an optimal monetary policy rule which modifies the synthetic version of the Taylor Rule. This model allows making short run comparative static analyses.
Quaternion orders, quadratic forms, and Shimura curves
Alsina, Montserrat
2004-01-01
Shimura curves are a far-reaching generalization of the classical modular curves. They lie at the crossroads of many areas, including complex analysis, hyperbolic geometry, algebraic geometry, algebra, and arithmetic. The text provides an introduction to the subject from a theoretic and algorithmic perspective. The main topics covered in it are Shimura curves defined over the rational number field, the construction of their fundamental domains, and the determination of their complex multiplication points. The study of complex multiplication points in Shimura curves leads to the study of families of binary quadratic forms with algebraic coefficients and to their classification by arithmetic Fuchsian groups. In this regard, the authors develop a theory full of new possibilities which parallels Gauss' theory on the classification of binary quadratic forms with integral coefficients by the action of the modular group. Each topic covered in the book begins with a theoretical discussion followed by carefully worked...
Galactic rotation curves and brane world models
Rahaman, F; De Benedictis, A; Usmani, A A; Ray, Saibal
2008-01-01
In the present investigation flat rotational curves of the galaxies are considered under the framework of brane-world models where the 4d effective Einstein equation has extra terms which arise from the embedding of the 3-brane in the $5d$ bulk. It has been shown here that these long range bulk gravitational degrees of freedom can act as a mechanism to yield the observed galactic rotation curves without the need for dark matter. The present model has the advantage that the observed rotation curves result solely from well-established non-local effects of gravitation, such as dark radiation and dark pressure under a direct use of the condition of flat rotation curves and does not invoke any exotic matter field.
Solid-state curved focal plane arrays
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.
Do labour supply and demand curves exist?
Fleetwood, S.
2014-01-01
The objective of this paper is to show that circumstantial and empirical evidence for the existence of labour supply and demand curves is at best inconclusive and at worst casts doubt on their existence. Because virtually all orthodox models of labour markets, simple and complex, are built upon the foundation stones of labour supply and demand curves, these models lack empirically supported foundations. Orthodox labour economists must, therefore, either provide stronger evidence or stop using...
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
We prove that (i) rank(K2(E)) 1 for all elliptic curves E defined over Q with a rational torsion point of exact order N 4; (ii) rank(K2(E)) 1 for all but at most one R-isomorphism class of elliptic curves E defined over Q with a rational torsion point of exact order 3. We give some sufficient conditions for rank(K2(EZ)) 1.
Chiral gap effect in curved space
Flachi, Antonino
2014-01-01
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.
Institute of Scientific and Technical Information of China (English)
JI QingZhong; QIN HouRong
2009-01-01
We prove that (i) rank(K2(E))≥1 for all elliptic curves E defined over Q with a rational torsion point of exact order N≥ 4;(ii) rank(K2(E))≥1 for all but at most one R-isomorphism class of elliptic curves E defined over Q with a rational torsion point of exact order 3.We give some sufficient conditions for rank(K2(Ez))≥1.
Smak, J
2016-01-01
Light curves of AM CVn are analyzed by decomposing them into their Fourier components. The amplitudes of the fundamental mode and overtones of the three components: the superhumps, the negative superhumps and the orbital variations, are found to be variable. This implies that variations in the shape of the observed light curve of AM CVn are not only due to the interference between those components, but also due to the variability of their parameters.
On local cohomology of a tetrahedral curve
Giang, Do Hoang
2009-01-01
It is shown that the diameter $\\diam (H^1_\\mfr(R/I))$ of the first local cohomology module of a tetrahedral curve $C= C(a_1,...,a_6)$ can be explicitly expressed in terms of the $a_i$ and is the smallest non-negative integer $k$ such that $\\mfr^k H^1_\\mfr(R/I)=0$. From that one can describe all arithmetically Cohen-Macaulay or Buchsbaum tetrahedral curves.
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.
Institute of Scientific and Technical Information of China (English)
汪志华; 戴林送; 陈素根; 苏本跃
2014-01-01
The cubic Timmer curve can interpolate the midpoint of the intermediate control edge of the control polygon, however, it can not tangent the control edge. And the cubic Timmer curve does not possess the convex hull property. In response to these flaws, this paper proposes one kind of curve(call it Timmer-like curve). The Timmer-like curve not only possesses some properties as the Timmer curve, but possesses the convex hull property, interpolates the midpoint of the second control edge of the control polygon, and the second control edge tangents the midpoint of the second control edge of the control polygon.%三次Timmer曲线能够插值的控制多边形中间控制边的中点，但它却不能保证与该控制边相切，且三次Tim-mer曲线不具有凸包性。针对于此，提出了一类曲线（称之拟Timmer曲线），拟Timmer曲线不仅具有与Timmer曲线所类似的性质，而且具有凸包性，且能够插值中间控制边的中点，并与之相切。
Ion guiding in curved glass capillaries
Energy Technology Data Exchange (ETDEWEB)
Kojima, Takao M. [Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Ikeda, Tokihiro [Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kanai, Yasuyuki; Yamazaki, Yasunori [Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)
2015-07-01
Straight and curved glass capillaries were tested for the guiding of 8 keV Ar{sup 8+} ion beams. The straight capillary was about 50 mm long and 0.87 mm/1.1 mm in inner/outer diameter. One of the two curved capillaries was similar, but was curved with a 270 mm radius. The other was 53 mm long, had diameters of 2.34 mm/2.99 mm, and was curved with a 150 mm radius. The corresponding bending angles of the two curved capillaries were 9.6° and 17.5°, respectively. Transmission through the straight capillary disappeared when the tilt angle was larger than 5°. The curved capillaries guided the ion beams into their corresponding bending angles, which were much larger than 5°, with transmission efficiencies of a few tens percent. This demonstrates the possibility of developing a new scheme of simple small beam deflectors and related beam optics.
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.
Geometric invariant theory for polarized curves
Bini, Gilberto; Melo, Margarida; Viviani, Filippo
2014-01-01
We investigate GIT quotients of polarized curves. More specifically, we study the GIT problem for the Hilbert and Chow schemes of curves of degree d and genus g in a projective space of dimension d-g, as d decreases with respect to g. We prove that the first three values of d at which the GIT quotients change are given by d=a(2g-2) where a=2, 3.5, 4. We show that, for a>4, L. Caporaso's results hold true for both Hilbert and Chow semistability. If 3.5curves. If 2curves. We also analyze in detail the critical values a=3.5 and a=4, where the Hilbert semistable locus is strictly smaller than the Chow semistable locus. As an application, we obtain three compactications of the universal Jacobian over the moduli space of stable curves, weakly-pseudo-stable curves and pseu...
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.
Null Similar Curves with Variable Transformations in Minkowski 3-space
Önder, Mehmet
2012-01-01
In this study, we define a family of null curves in Minkowski 3-space and called null similar curves. We obtain some properties of these special curves. We show that two null curves are null similar curves if and only if these curves form a null Bertrand pair. Moreover, we obtain that the family of null geodesics and null helices form the families of null similar curves with variable transformation.
Phonon transport across nano-scale curved thin films
Mansoor, Saad B.; Yilbas, Bekir S.
2016-12-01
Phonon transport across the curve thin silicon film due to temperature disturbance at film edges is examined. The equation for radiative transport is considered via incorporating Boltzmann transport equation for the energy transfer. The effect of the thin film curvature on phonon transport characteristics is assessed. In the analysis, the film arc length along the film centerline is considered to be constant and the film arc angle is varied to obtain various film curvatures. Equivalent equilibrium temperature is introduced to assess the phonon intensity distribution inside the curved thin film. It is found that equivalent equilibrium temperature decay along the arc length is sharper than that of in the radial direction, which is more pronounced in the region close to the film inner radius. Reducing film arc angle increases the film curvature; in which case, phonon intensity decay becomes sharp in the close region of the high temperature edge. Equivalent equilibrium temperature demonstrates non-symmetric distribution along the radial direction, which is more pronounced in the near region of the high temperature edge.
Phonon transport across nano-scale curved thin films
Energy Technology Data Exchange (ETDEWEB)
Mansoor, Saad B.; Yilbas, Bekir S., E-mail: bsyilbas@kfupm.edu.sa
2016-12-15
Phonon transport across the curve thin silicon film due to temperature disturbance at film edges is examined. The equation for radiative transport is considered via incorporating Boltzmann transport equation for the energy transfer. The effect of the thin film curvature on phonon transport characteristics is assessed. In the analysis, the film arc length along the film centerline is considered to be constant and the film arc angle is varied to obtain various film curvatures. Equivalent equilibrium temperature is introduced to assess the phonon intensity distribution inside the curved thin film. It is found that equivalent equilibrium temperature decay along the arc length is sharper than that of in the radial direction, which is more pronounced in the region close to the film inner radius. Reducing film arc angle increases the film curvature; in which case, phonon intensity decay becomes sharp in the close region of the high temperature edge. Equivalent equilibrium temperature demonstrates non-symmetric distribution along the radial direction, which is more pronounced in the near region of the high temperature edge.
Application of Master Curve Methodology for Structural Integrity Assessments of Nuclear Components
Energy Technology Data Exchange (ETDEWEB)
Sattari-Far, Iradj [Det Norske Veritas, Stockholm (Sweden); Wallin, Kim [VTT, Esbo (Finland)
2005-10-15
The objective was to perform an in-depth investigation of the Master Curve methodology and also based on this method develop a procedure for fracture assessments of nuclear components. The project has sufficiently illustrated the capabilities of the Master Curve methodology for fracture assessments of nuclear components. Within the scope of this work, the theoretical background of the methodology and its validation on small and large specimens has been studied and presented to a sufficiently large extent, as well as the correlations between the charpy-V data and the Master Curve T{sub 0} reference temperature in the evaluation of fracture toughness. The work gives a comprehensive report of the background theory and the different applications of the Master Curve methodology. The main results of the work have shown that the cleavage fracture toughness is characterized by a large amount of statistical scatter in the transition region, it is specimen size dependent and it should be treated statistically rather than deterministically. The Master Curve methodology is able to make use of statistical data in a consistent way. Furthermore, the Master Curve methodology provides a more precise prediction of the fracture toughness of embrittled materials in comparison with the ASME K{sub IC} reference curve, which often gives over-conservative results. The suggested procedure in this study, concerning the application of the Master Curve method in fracture assessments of ferritic steels in the transition region and the low shelf regions, is valid for the temperatures range T{sub 0}-50{<=}T{<=}T{sub 0}+50 deg C. If only approximate information is required, the Master Curve may well be extrapolated outside this temperature range. The suggested procedure has also been illustrated for some examples.
Exact Finite Element Formulation of Frenet Formula of Curve in Geospatial Database
Wang, J.; Xiao, J.
2014-04-01
Directly using the difference form of Frenet formula will cause the three basic vectors losing their orthogonal features rapidly. As the analytic form is exact for infinite short length region, for finite length segregation, the omitted items should be retrieved to get high precision. Based on the unit orthogonal transformation in geometrical field theory, the Frenet formula is reformed for finite length region. Then, for given triple at the initial end of curve, using the curve parameters of curvature and torsion, the exact finite element formulation of Frenet formula is obtained to get the triples at any length position until the end point of curve. This method can be used as a high-precision technology for the measure, store, and retrieve of complicated curve.
Directory of Open Access Journals (Sweden)
Luis Carlos Cunha Junior
2007-01-01
Full Text Available O objetivo deste trabalho foi caracterizar a curva de maturação de pêssegos 'Aurora-1' para a região de Jaboticabal-SP, através de avaliações físicas e químicas dos frutos. O experimento foi conduzido em pomar comercial, no município de Vista Alegre do Alto, onde foram marcados ramos de 15 plantas, com flores no estádio de "balão". Após 20 dias, iniciou-se a coleta dos frutos, com intervalos de 7 dias, até a sua maturação completa (111 dias. Através dos dados de altura e de diâmetro, verificou-se que os frutos da cultivar 'Aurora-1' seguiram o padrão de crescimento semelhante ao encontrado na literatura, que é de uma curva sigmoidal dupla, atingindo no final da maturação altura de 59,84±6,9 mm e diâmetro de 50,30±5,8 mm. Em relação ao peso dos frutos no período de 90 a 111 dias, houve incremento de 41,08 g para 58,82 g (43%. O teor de ácidos orgânicos e a firmeza diminuíram na mesma proporção em que ocorreu o aumento no conteúdo de sólidos solúveis e carboidratos solúveis durante o período de desenvolvimento. A coloração interna do fruto evoluiu, passando de amarelo-esverdeada para amarelo- intensa. A cor de fundo nas duas primeiras amostragens apresentaram valores semelhantes à cor interna, evoluindo a partir desse ponto de amarelo-esverdeada para alaranjada. Já a cor de recobrimento teve uma diferença mais pronunciada, passando de amarelo-esverdeada para vermelho-intensa, característica da cultivar. Esses resultados sinalizaram que, aos 90 e 97 dias, os frutos atingiram sua maturação fisiológica e que, aos 104 e 111 dias, encontravam-se sobremaduros.The aim of this work was to characterize the maturation stage of peaches 'Aurora-1' for the region of Jaboticabal, SP, Brazil. The experiment was conduced in a commercial orchard in Vista Alegre do Alto, where branches of 15 trees were marked with flowers in "balloon" stage. After 20 days, fruits were harvested, every 7 days (or once a week until the
ANTIPLANE CIRCULAR INCLUSION WITH A CURVED CRACK CROSSING THE BOUNDARY
Institute of Scientific and Technical Information of China (English)
Lu Jianfei; Wang Jianhua; Shen Weiping
2000-01-01
The weakly singular integral equation used to solve the problem of the curved crack crossing the boundary of the antiplane circular inclusion is presented. Using the principal part analysis method of the Cauchy type integral equation, the singular stress index at the intersection and the singular stress of angular regions near the intersection are obtained. By using the singular stress obtained, the stress intensity factor at the intersection is defined. After the numerical solution of the integral equation, the stress intensity factors at the end points of the crack and intersection are obtainable.
Refraction at a curved dielectric interface - Geometrical optics solution
Lee, S.-W.; Sheshadri, M. S.; Mittra, R.; Jamnejad, V.
1982-01-01
The transmission of a spherical or plane wave through an arbitrarily curved dielectric interface is solved by the geometrical optics theory. The transmitted field is proportional to the product of the conventional Fresnel's transmission coefficient and a divergence factor (DF), which describes the cross-sectional variation (convergence or divergence) of a ray pencil as the latter propagates in the transmitted region. The factor DF depends on the incident wavefront, the curvatures of the interface, and the relative indices of the two media. Explicit matrix formulas for calculating DF are given, and its physical significance is illustrated via examples.
Exchange Rate and Trade: J-curve in European Union
Directory of Open Access Journals (Sweden)
Dan Lupu
2014-06-01
Full Text Available The EU economy is experiencing a severe recession amid the global crisis, and although in other regions began to appear mild signs of recovery, in EU countries are recorded a continuously worsening. In many European states, the economic contraction is a consequence of the decrease in net exports component of GDP. The aim of the article is to analyze the situation in which the EU chooses to devalue its currency to increase exports. We found that, the depreciation of the Euro, has no influence on exports and that in EU, it is not expressed a J-curve effects.
Light waves guided by a single curved metallic surface.
Krammer, H
1978-01-15
Propagation of TE-waves along a single curved metallic surface with radius of curvature much larger than wavelength is investigated both theoretically and experimentally. Approximate analytic expressions for the field configuration yield that power concentrates in a small region near the metal. The attenuation constant per unit angle of bend (radian) is given by the real part of the inverse of the refractive index, independent of the radius of curvature and of the mode number. In agreement with theory experiments with 10-microm radiation showed that low loss guiding can be realized.
Calculation of Shock Hugoniot Curves of Precompressed Liquid Deuterium
Energy Technology Data Exchange (ETDEWEB)
Militzer, B
2002-11-18
Path integral Monte Carlo simulations have been used to study deuterium at high pressure and temperature. The equation of state has been derived in the temperature and density region of 10,000 {le} T {le} 1,000,000 and 0.6 {le} {rho} {le} 2.5 g cm{sup -3}. A series of shock Hugoniot curves is computed for different initial compressions in order to compare with current and future shock wave experiments using liquid deuterium samples precompressed in diamond anvil cells.
Higher dimensional curved domain walls on Kähler surfaces
Akbar, Fiki T.; Gunara, Bobby E.; Radjabaycolle, Flinn C.; Wijaya, Rio N.
2017-03-01
In this paper we study some aspects of curved BPS-like domain walls in higher dimensional gravity theory coupled to scalars where the scalars span a complex Kähler surface with scalar potential turned on. Assuming that a fake superpotential has a special form which depends on Kähler potential and a holomorphic function, we prove that BPS-like equations have a local unique solution. Then, we analyze the vacuum structure of the theory including their stability using dynamical system and their existence in ultraviolet-infrared regions using renormalization group flow.
Higher dimensional curved domain walls on Kähler surfaces
Energy Technology Data Exchange (ETDEWEB)
Akbar, Fiki T., E-mail: ftakbar@fi.itb.ac.id [Theoretical Physics Laboratory, Theoretical High Energy Physics and Instrumentation Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha no. 10 Bandung, 40132 (Indonesia); Gunara, Bobby E., E-mail: bobby@fi.itb.ac.id [Theoretical Physics Laboratory, Theoretical High Energy Physics and Instrumentation Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha no. 10 Bandung, 40132 (Indonesia); Radjabaycolle, Flinn C. [Theoretical Physics Laboratory, Theoretical High Energy Physics and Instrumentation Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha no. 10 Bandung, 40132 (Indonesia); Departement of Physics, Faculty of Mathematics and Natural Sciences, Cendrawasih University, Jl. Kampwolker Kampus Uncen Baru Waena-Jayapura 99351 (Indonesia); Wijaya, Rio N. [Theoretical Physics Laboratory, Theoretical High Energy Physics and Instrumentation Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha no. 10 Bandung, 40132 (Indonesia)
2017-03-15
In this paper we study some aspects of curved BPS-like domain walls in higher dimensional gravity theory coupled to scalars where the scalars span a complex Kähler surface with scalar potential turned on. Assuming that a fake superpotential has a special form which depends on Kähler potential and a holomorphic function, we prove that BPS-like equations have a local unique solution. Then, we analyze the vacuum structure of the theory including their stability using dynamical system and their existence in ultraviolet-infrared regions using renormalization group flow.
Three-Body Choreographies in Given Curves
Ozaki, Hiroshi; Fujiwara, Toshiaki
2009-01-01
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 determines the motion of the planet completely. Even in the three-body problem, in some cases, the shape of the orbit, conservation of the centre of mass and a constant of motion (the angular momentum or the total energy) determines 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 a 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 ...
EFFICIENT MAPPING METHODS FOR ELLIPTIC CURVE CRYPTOSYSTEMS
Directory of Open Access Journals (Sweden)
O.SRINIVASA RAO
2010-08-01
Full Text Available The generic name for collection of tools designed to protect data and thwart hackers is Computer Security. The major change that affected security was the introduction of distributed systems and the use of networks and communication facilities for carrying data between terminal user and computer and computer and computer. Network security measures are needed to protect data transmission. Suppose that we had a way of masking the contents of messages or other information traffic so that an attacker, even if he or she captured the message, would be unable to extract the information from the message. The common technique for doing masking is encryption. The encryption is done by using Symmetric key or public key Algorithms. The most commonly used public key algorithms are 1. Rivest Shamir Adelman(RSA and 2 Elliptic Curve cryptography In this paper two different mapping methods of the alphanumeric characters on to the x-y co ordinate of the Elliptic curve defined over a finite field Zp is proposed. The methods are 1 Static (One-to-One Mapping Method and 2 Dynamic (One-to-N Mapping Method. Dynamic mapping method will increase the strength of the Elliptic Cryptosystem. The Results have been attached. The hardness of the elliptic curve discrete logarithm problem (ECDLP is crucial for the security of elliptic curve cryptographic schemes. This report describes the state-of-the-art in mapping the alphanumerical characters on to the x-y coordinates of the elliptic curve points.
Critical Factors for Inducing Curved Somatosensory Saccades
Directory of Open Access Journals (Sweden)
Tamami Nakano
2011-10-01
Full Text Available We are able to make a saccade toward a tactile stimuli to one hand, but trajectories of many saccades curved markedly when the arms were crossed (Groh & Sparks, 2006. However, it remains unknown why some curved and others did not. We therefore examined critical factors for inducing the curved somatosensory saccades. Participants made a saccade as soon as possible from a central fixation point toward a tactile stimulus delivered to one of the two hands, and switched between arms-crossed and arms-uncrossed postures every 6 trials. Trajectories were generally straight when the arms were uncrossed, but all participants made curved saccades when the arms were crossed (12–64%. We found that the probability of curved saccades depended critically on the onset latency: the probability was less than 5% when the latency was larger than 250 ms, but the probability increased up to 70–80% when the onset latency was 160 ms. This relationship was shared across participants. The results suggest that a touch in the arms-crossed posture was always mapped to the wrong hand in the initial phase up to 160 ms, and then remapped to the correct hand during the next 100 ms by some fundamental neural mechanisms shared across participants.
Probing exoplanet clouds with optical phase curves
Munoz, A Garcia
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...
Cylindrical Helix Spline Approximation of Spatial Curves
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
In this paper, we present a new method for approximating spatial curves with a G1 cylindrical helix spline within a prescribed tolerance. We deduce the general formulation of a cylindrical helix,which has 11 freedoms. This means that it needs 11 restrictions to determine a cylindrical helix. Given a spatial parametric curve segment, including the start point and the end point of this segment, the tangent and the principal normal of the start point, we can always find a cylindrical segment to interpolate the given direction and position vectors. In order to approximate the known parametric curve within the prescribed tolerance, we adopt the trial method step by step. First, we must ensure the helix segment to interpolate the given two end points and match the principal normal and tangent of the start point, and then, we can keep the deviation between the cylindrical helix segment and the known curve segment within the prescribed tolerance everywhere. After the first segment had been formed, we can construct the next segment. Circularly, we can construct the G1 cylindrical helix spline to approximate the whole spatial parametric curve within the prescribed tolerance. Several examples are also given to show the efficiency of this method.
Fractal Correction of Well Logging Curves
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
It is always significant for assessing and evaluation of oil-bearing layers, especially for well logging data processing and interpretation of non-marine oil beds to get more accurate physical properties in thin and inter-thin layers. This paper presents a definition of measures and the measure presents power law relation with the corresponded scale described by fractal theory. Thus, logging curves can be reconstructed according to this power law relation. This method uses the local structure nearby concurrent points to com pensate the average effect of logging probes and measurement errors. As an example, deep and medium induced conductivity (IMPH and IDPH) curves in ODP Leg 127 Hole 797C are reconstructed or corrected. Corrected curves are with less adjacent effects through comparison of corrected curves with original one. And also, the power spectra of corrected well logging curve are abounding with more resolution components than the original one. Thus, fractal correction method makes the well logging more resoluble for thin beds.``
IDENTIFICATION OF NONLINEAR DYNAMIC SYSTEMS:TIME-FREQUENCY FILTERING AND SKELETON CURVES
Institute of Scientific and Technical Information of China (English)
王丽丽; 张景绘
2001-01-01
The nonlinear behavior varying with the instantaneous response was analyzed through the joint time-frequency analysis method for a class of S. D. O . F nonlinear system.A masking operator on definite regions is defined and two theorems are presented. Based on these, the nonlinear system is modeled with a special time-varying linear one, called the generalized skeleton linear system ( GSLS ). The frequency skeleton curve and the damping skeleton curve are defined to describe the main feature of the non-linearity as well. More over, an identification method is proposed through the skeleton curves and the time frequency filtering technique.
Comparison of ductile-to-brittle transition curve fitting approaches
Energy Technology Data Exchange (ETDEWEB)
Cao, L.W. [School of Materials Science and Engineering, Beihang University (BUAA), Beijing 100191 (China)] [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR (United Kingdom); Wu, S.J., E-mail: wusj@buaa.edu.cn [School of Materials Science and Engineering, Beihang University (BUAA), Beijing 100191 (China); Flewitt, P.E.J. [Interface Analysis Centre, University of Bristol, Bristol BS2 8BS (United Kingdom)] [School of Physics, HH Wills Laboratory, University of Bristol, BS8 1TL (United Kingdom)
2012-05-15
Ductile-to-brittle transition (DBT) curve fitting approaches are compared over the transition temperature range for reactor pressure vessel steels with different kinds of data, including Charpy-V notch impact energy data and fracture toughness data. Three DBT curve fitting methods have been frequently used in the past, including the Burr S-Weibull and tanh distributions. In general there is greater scatter associated with test data obtained within the transition region. Therefore these methods give results with different accuracies, especially when fitting to small quantities of data. The comparison shows that the Burr distribution and tanh distribution can almost equally fit well distributed and large data sets extending across the test temperature range to include the upper and lower shelves. The S-Weibull distribution fit is poor for the lower shelf of the DBT curve. Overall for both large and small quantities of measured data the Burr distribution provides the best description. - Highlights: Black-Right-Pointing-Pointer Burr distribution offers a better fit than that of a S-Weibull and tanh fit. Black-Right-Pointing-Pointer Burr and tanh methods show similar fitting ability for a large data set. Black-Right-Pointing-Pointer Burr method can fit sparse data well distributed across the test temperature. Black-Right-Pointing-Pointer S-Weibull method cannot fit the lower shelf well and show poor fitting quality.
The unexpected diversity of dwarf galaxy rotation curves
Oman, Kyle A; Fattahi, Azadeh; Frenk, Carlos S; Sawala, Till; White, Simon D M; Bower, Richard; Crain, Robert A; Furlong, Michelle; Schaller, Matthieu; Schaye, Joop; Theuns, Tom
2015-01-01
We examine the circular velocity profiles of galaxies in {\\Lambda}CDM cosmological hydrodynamical simulations from the EAGLE and LOCAL GROUPS projects and compare them with a compilation of observed rotation curves of galaxies spanning a wide range in mass. The shape of the circular velocity profiles of simulated galaxies varies systematically as a function of galaxy mass, but shows remarkably little variation at fixed maximum circular velocity. This is especially true for low-mass dark matter-dominated systems, reflecting the expected similarity of the underlying cold dark matter haloes. This is at odds with observed dwarf galaxies, which show a large diversity of rotation curve shapes, even at fixed maximum rotation speed. Some dwarfs have rotation curves that agree well with simulations, others do not. The latter are systems where the inferred mass enclosed in the inner regions is much lower than expected for cold dark matter haloes and include many galaxies where previous work claims the presence of a con...
Genomic growth curves of an outbred pig population
Directory of Open Access Journals (Sweden)
Fabyano Fonseca e Silva
2013-01-01
Full Text Available In the current post-genomic era, the genetic basis of pig growth can be understood by assessing SNP marker effects and genomic breeding values (GEBV based on estimates of these growth curve parameters as phenotypes. Although various statistical methods, such as random regression (RR-BLUP and Bayesian LASSO (BL, have been applied to genomic selection (GS, none of these has yet been used in a growth curve approach. In this work, we compared the accuracies of RR-BLUP and BL using empirical weight-age data from an outbred F2 (Brazilian Piau X commercial population. The phenotypes were determined by parameter estimates using a nonlinear logistic regression model and the halothane gene was considered as a marker for evaluating the assumptions of the GS methods in relation to the genetic variation explained by each locus. BL yielded more accurate values for all of the phenotypes evaluated and was used to estimate SNP effects and GEBV vectors. The latter allowed the construction of genomic growth curves, which showed substantial genetic discrimination among animals in the final growth phase. The SNP effect estimates allowed identification of the most relevant markers for each phenotype, the positions of which were coincident with reported QTL regions for growth traits.
Dean Instability in Double-Curved Channels
Debus, J -D; Herrmann, H J
2014-01-01
We study the Dean instability in curved channels using the lattice Boltzmann model for generalized metrics. For this purpose, we first improve and validate the method by measuring the critical Dean number at the transition from laminar to vortex flow for a streamwise curved rectangular channel, obtaining very good agreement with the literature values. Taking advantage of the easy implementation of arbitrary metrics within our model, we study the fluid flow through a double-curved channel, using ellipsoidal coordinates, and study the transition to vortex flow in dependence of the two perpendicular curvature radii of the channel. We observe not only transitions to 2-cell vortex flow, but also to 4-cell and even 6-cell vortex flow, and we find that the critical Dean number at the transition to 2-cell vortex flow exhibits a minimum when the two curvature radii are approximately equal.
Curved Nanotube Structures under Mechanical Loading
Directory of Open Access Journals (Sweden)
Hamidreza Yazdani Sarvestani
2015-01-01
Full Text Available Configuration of carbon nanotube (CNT has been the subject of research to perform theoretical development for analyzing nanocomposites. A new theoretical solution is developed to study curved nanotube structures subjected to mechanical loadings. A curved nanotube structure is considered. A nonlocal displacement-based solution is proposed by using a displacement approach of Toroidal Elasticity based on Eringen’s theory of nonlocal continuum mechanics. The governing equations of curved nanotube structures are developed in toroidal coordinate system. The method of successive approximation is used to discretize the displacement-based governing equations and find the general solution subjected to bending moment. The numerical results show that all displacement components increase with increasing the nonlocal parameter. The present theoretical study highlights the significance of the geometry and nonlocal parameter effects on mechanical behavior of nanotube structures.
Galois Lines for Normal Elliptic Space Curves
Institute of Scientific and Technical Information of China (English)
Ma. Cristina Lumakin Duyaguit; Hisao Yoshihara
2005-01-01
Let C be a curve, and l and lO be lines in the projective three space P3.Consider a projection πl: P3... → lO with center l, where l ∩ lO = 0. Restricting πl to C,we obtain a morphism πl |C: C → lO and an extension of fields (πl|C)*: k(lO) → k(C). If this extension is Galois, then l is said to be a Galois line. We study the defining equations,automorphisms and the Galois lines for quartic curves, and give some applications to the theory ofplane quartic curves.
Pandharipande, R
2011-01-01
In the past 20 years, compactifications of the families of curves in algebraic varieties X have been studied via stable maps, Hilbert schemes, stable pairs, unramified maps, and stable quotients. Each path leads to a different enumeration of curves. A common thread is the use of a 2-term deformation/obstruction theory to define a virtual fundamental class. The richest geometry occurs when X is a nonsingular projective variety of dimension 3. We survey here the 13/2 principal ways to count curves with special attention to the 3-fold case. The different theories are linked by a web of conjectural relationships which we highlight. Our goal is to provide a guide for graduate students looking for an elementary route into the subject.
Mathematical design of a highway exit curve
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.
Asymmetry Dependence of the Nuclear Caloric Curve
McIntosh, Alan B; Cammarata, Paul; Hagel, Kris; Heilborn, Lauren; Kohley, Zachary; Mabiala, Justin; May, Larry W; Marini, Paola; Raphelt, Andrew; Souliotis, George A; Wuenschel, Sara; Zarrella, Andrew; Yennello, Sherry J
2012-01-01
A basic feature of the nuclear equation of state is not yet understood: the dependence of the nuclear caloric curve on the neutron-proton asymmetry. Predictions of theoretical models differ on the magnitude and even the sign of this dependence. In this work, the nuclear caloric curve is examined for fully reconstructed quasi-projectiles around mass A=50. The caloric curve extracted with the momentum quadrupole fluctuation thermometer shows that the temperature varies linearly with quasi-projectile asymmetry (N-Z)/A. An increase in asymmetry of 0.15 units corresponds to a decrease in temperature on the order of 1 MeV. These results also highlight the importance of a full quasi-projectile reconstruction in the study of thermodynamic properties of hot nuclei.
Migration and the Wage-Settings Curve
DEFF Research Database (Denmark)
Brücker, Herbert; Jahn, Elke
Germany on basis of a wage-setting curve. The wage-setting curve relies on the assumption that wages respond to a hange in the unemployment rate, albeit imperfectly. This allows one to derive the wage and employment effects of migration simultaneously in a general equilibrium framework. Using...... administrative micro data we find that the elasticity of the wage-setting curve is particularly high for young workers and workers with an university degree, while it is low for older workers and workers with a vocational degree. The wage and employment effects of migration are moderate: a 1 percent increase...... in the German labor force through immigration increases the aggregate unemployment rate by less than 0.1 percentage points and reduces average wages by 0.1 percent in the short run. While native workers benefit from increased wages and lower unemployment, foreign workers are adversely affected....
Experimental Simulation of Closed Timelike Curves
Ringbauer, Martin; Myers, Casey R; White, Andrew G; Ralph, Timothy C
2015-01-01
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 non-linearities and the emergence of causal structures in quantum mechanics-essential for any formulation of a quantum theory of gravity. Here we experimentally simulate the non-linear 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 t...
Energy dissipation in flows through curved spaces
Debus, J.-D.; Mendoza, M.; Succi, S.; Herrmann, H. J.
2017-01-01
Fluid dynamics in intrinsically curved geometries is encountered in many physical systems in nature, ranging from microscopic bio-membranes all the way up to general relativity at cosmological scales. Despite the diversity of applications, all of these systems share a common feature: the free motion of particles is affected by inertial forces originating from the curvature of the embedding space. Here we reveal a fundamental process underlying fluid dynamics in curved spaces: the free motion of fluids, in the complete absence of solid walls or obstacles, exhibits loss of energy due exclusively to the intrinsic curvature of space. We find that local sources of curvature generate viscous stresses as a result of the inertial forces. The curvature- induced viscous forces are shown to cause hitherto unnoticed and yet appreciable energy dissipation, which might play a significant role for a variety of physical systems involving fluid dynamics in curved spaces. PMID:28195148
Surface growth kinematics via local curve evolution
Moulton, Derek E.
2012-11-18
A mathematical framework is developed to model the kinematics of surface growth for objects that can be generated by evolving a curve in space, such as seashells and horns. Growth is dictated by a growth velocity vector field defined at every point on a generating curve. A local orthonormal basis is attached to each point of the generating curve and the velocity field is given in terms of the local coordinate directions, leading to a fully local and elegant mathematical structure. Several examples of increasing complexity are provided, and we demonstrate how biologically relevant structures such as logarithmic shells and horns emerge as analytical solutions of the kinematics equations with a small number of parameters that can be linked to the underlying growth process. Direct access to cell tracks and local orientation enables for connections to be made to the underlying growth process. © 2012 Springer-Verlag Berlin Heidelberg.
Approaches for Constrained Parametric Curve Interpolation
Institute of Scientific and Technical Information of China (English)
ZHANG CaiMing(张彩明); YANG XingQiang(杨兴强); WANG JiaYe(汪嘉业)
2003-01-01
The construction of a GC 1 cubic interpolating curve that lies on the same side of agiven straight line as the data points is studied. The main task is to choose appropriate approachesto modify tangent vectors at the data points for the desired curve. Three types of approaches forchanging the magnitudes of the tangent vectors are presented. The first-type approach nodifiesthe tangent vectors by applying a constraint to the curve segment. The second one does the workby optimization techniques. The third one is a modification of the existing method. Three criteriaare presented to compare the three types of approaches with the existing method. The experimentsthat test the effectiveness of the approaches are included.
Minimal families of curves on surfaces
Lubbes, Niels
2014-11-01
A minimal family of curves on an embedded surface is defined as a 1-dimensional family of rational curves of minimal degree, which cover the surface. We classify such minimal families using constructive methods. This allows us to compute the minimal families of a given surface.The classification of minimal families of curves can be reduced to the classification of minimal families which cover weak Del Pezzo surfaces. We classify the minimal families of weak Del Pezzo surfaces and present a table with the number of minimal families of each weak Del Pezzo surface up to Weyl equivalence.As an application of this classification we generalize some results of Schicho. We classify algebraic surfaces that carry a family of conics. We determine the minimal lexicographic degree for the parametrization of a surface that carries at least 2 minimal families. © 2014 Elsevier B.V.
A Radiosity Solution for Curved Surface Environments
Institute of Scientific and Technical Information of China (English)
孙济洲; RichardL.Grimsdale
1997-01-01
Radiosity has been a popular method for photorealistic image generation.But the determination of form factors between curved patches is the most difficult and time consuming procedure,and also the errors caused by approximating source patch's radiosity with average values are obvious.In this paper,a radiosity algorithm for rendering curved surfaces represented by parameters is described.The contributed radiosity from differential areas on four vertices of the source patch to a receiving point is calculated firstly,then the contribution from the inner area of the source patch is evaluated by interpolating the values on four corners.Both the difficult problem of determining form-factors between curved surfaces and errors mentioned above have been avoided.Comparison of the experimental results using the new algorithm has been made with the ones obtained by traditional method.Some associated techniques such as the visibility test and the adaptive subdivision are also described.
Differential geometry of curves and surfaces
Banchoff, Thomas F
2010-01-01
Students and professors of an undergraduate course in differential geometry will appreciate the clear exposition and comprehensive exercises in this book that focuses on the geometric properties of curves and surfaces, one- and two-dimensional objects in Euclidean space. The problems generally relate to questions of local properties (the properties observed at a point on the curve or surface) or global properties (the properties of the object as a whole). Some of the more interesting theorems explore relationships between local and global properties. A special feature is the availability of accompanying online interactive java applets coordinated with each section. The applets allow students to investigate and manipulate curves and surfaces to develop intuition and to help analyze geometric phenomena.
Experimental simulation of closed timelike curves.
Ringbauer, Martin; Broome, Matthew A; Myers, Casey R; White, Andrew G; Ralph, Timothy C
2014-06-19
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.
Plasticity and rectangularity in survival curves
Weon, Byung Mook; Je, Jung Ho
2011-09-01
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.
The genus curve of the Abell clusters
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).
Relative Locality in Curved Space-time
Kowalski-Glikman, Jerzy
2013-01-01
In this paper we construct the action describing dynamics of the particle moving in curved spacetime, with a non-trivial momentum space geometry. Curved momentum space is the core feature of theories where relative locality effects are presents. So far aspects of nonlinearities in momentum space have been studied only for flat or constantly expanding (De Sitter) spacetimes, relying on the 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 kappa-Poincar\\'e 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.
Characteristic Drying Curve of Oil Palm Fibers
Directory of Open Access Journals (Sweden)
Ifa Puspasari
2014-03-01
Full Text Available The drying of crushed oil palm fronds was studied in a fluidized bed dryer assisted with mechanical agitation at different inlet air temperature, superficial air velocity, bed loading and agitation speed. The drying kinetics of the fibers under various drying conditions could be described by a single characteristic drying curve. A combined exponential and power law model is proposed to represent the characteristic drying curve which described both the increasing rate and the falling rate periods. The proposed model is also tested for drying kinetics of oil palm empty fruit bunch from previous researcher. It was found that the characteristic curve for both oil palm fronds and empty fruit bunch fibers has similar shape and that the proposed model is acceptable for describing the complete drying characteristics of the fibers.
POSSIBLE RECESSION CURVE APPLICATIONS FOR RETENTION EVALUATION
Directory of Open Access Journals (Sweden)
Daniel Liberacki
2015-11-01
Full Text Available The objective of the article was to present possible applications of recession flow curve in a small lowland watershed retention discharge size evaluation. The examined woodland micro catchment area of 0.52 sq km is located in Puszcza Zielonka in central Wielkopolska. The Hutka catchment is typically woody with high retention abilities. The catchment of the Hutka watercourse is forested in 89%, the other 11% is covered by swamps and wasteland. The predominant sites are fresh mixed coniferous forest (BMśw, fresh coniferous forest (Bśw and alder carr forest (Ol. Landscape in catchment is characterized by a large number of interior depressions, filled partly with rainwater or peatbogs, with poorly developed natural drainage. The watercourses do not exceed 1 km in length, the mean width is approx. 0.5 m, while mean depth ranges from 0.2 to 0.3 m. During hydrological research conducted in 1997/1998–1999/2000, 35 major (characteristic raised water stages were observed in Hutka after substantial precipitation. The recession curve dating from 18–24 September 2000 has the α and n rates nearest to average. Comparing the model curve and the curve created by observing watercourse flow, one can notice their resemblance and that they have similar ordinate values as well as shape. In the case of other recession curves, the maximum differences of ordinate values are also about 0.1–0.2 l/s/km2. The measuured α and n rates do not reveal any regularities. There are no significant statistical Horton model parameter (for recession flow curves dependencies between α and n and e.g. initial flows (Qo or the whole period of high water waves (Qp. Consequently, calculated relation between these parameters is only an approximation for the general evaluation of the retention discharge in the catchment area towards retention with flow function.
Directory of Open Access Journals (Sweden)
Marco Antonio Cossio-Bolaños
2012-09-01
Full Text Available OBJETIVO: Determinar a aplicabilidade do uso das curvas de crescimento da Organização Mundial da Saúde (OMS em escolares que vivem em regiões de altitude moderada. MÉTODOS: Estudo transversal cuja população foi constituída por uma amostra probabilística estratificada com 955 crianças e adolescentes de seis a 12 anos, sendo 473 meninos e 482 meninas que frequentavam escolas públicas da área urbana da Região de Arequipa (Peru. As variáveis avaliadas envolveram medidas de massa corpórea (kg e estatura (m e índice de massa corporal. Para as comparações, utilizou-se o escore Z e o teste t para medidas pareadas. RESULTADOS: Os meninos apresentaram valores similares de massa corpórea quando comparados com a referência. No entanto, as meninas mostraram valores superiores à referência nas idades de seis, sete e dez anos (pOBJETIVO: Determinar la aplicabilidad del uso de curvas de crecimiento de la Organización Mundial de la Salud en escolares que viven en regiones de altitud moderada. MÉTODOS: Estudio transversal, cuya población fue constituida por una muestra probabilística estratificada con 955 niños y adolescentes de seis a 12 años de edad, siendo 473 muchachos y 482 muchachas, que frecuentaban escuelas públicas de área urbana de la Región de Arequipa (Perú. Las variables evaluadas implicaron medidas de masa corporal (kg y estatura (m y el índice de masa corporal. Para las comparaciones, se utilizó el escore Z y la prueba t para medidas pareadas. RESULTADOS: Los muchachos presentaron valores similares de masa corporal cuando comparados con la referencia. Sin embargo, las muchachas mostraron valores superiores a la referencia en las edades de seis, siete y diez años (pOBJECTIVE: To determine the applicability of the World Health Organization growth curves in school children that live in areas of moderate altitude. METHODS: A cross-sectional study, using a stratified random sample of 955 children and adolescents aged 6
Covariance, Curved Space, Motion and Quantization
Directory of Open Access Journals (Sweden)
Apostol M.
2008-01-01
Full Text Available Weak external forces and non-inertial motion are equivalent with thefree motion in a curved space. The Hamilton-Jacobi equation is derivedfor such motion and the effects of the curvature upon the quantizationare analyzed, starting from a generalization of the Klein-Gordon equation in curved spaces. It is shown that the quantization is actually destroyed, in general, by a non-inertial motion in the presence of external forces, in the sense that such a motion may produce quantum transitions. Examples are given for a massive scalar field and for photons.
Principal normal indicatrices of closed space curves
DEFF Research Database (Denmark)
Røgen, Peter
1997-01-01
A theorem due to J. Weiner, which also is proven by B. Solomon, implies that a principal normal indicatrix of a closed space curve with non-vanishing curvature has integrated geodesic curvature zero and contains no sub arc with integrated geodesic curvature Pi. We prove that the inverse problem...... always has solutions if one allows zero and negative curvature of space curves and explain why this not is true if non-vanishing curvature is required. This answers affirmatively an open question asked by W. Fenchel in 1950 under the above assumptions but in general this question is found to be answered...
Phonon dispersion curves of CsCN
Indian Academy of Sciences (India)
N K Gaur; Preeti Singh; E G Rini; Jyotsna Galgale; R K Singh
2004-08-01
The motivation for the present work was gained from the recent publication on phonon dispersion curves (PDCs) of CsCN from the neutron scattering technique. We have applied the extended three-body force shell model (ETSM) by incorporating the effect of coupling between the translation modes and the orientation of cyanide molecules for the description of phonon dispersion curves of CsCN between the temperatures 195 and 295 K. Our results on PDCs in symmetric direction are in good agreement with the experimental data measured with inelastic neutron scattering technique.
The learning curves of competitive programming
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.
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. ini...
On curves on sandwiched surface singularities
Fernandez-Sanchez, Jesus
2007-01-01
Fixed a point O on a non-singular surface S and a complete mO-primary ideal I in its local ring, the curves on the surface X obtained by blowing-up I are studied in terms of the base points of I. Criteria for the principality of these curves are obtained. New formulas for their multiplicity, intersection numbers and order of singularity at the singularities of X are given. The semigroup of branches going through a sandwiched singularity is effectively determined, too.
Angles between Curves in Metric Measure Spaces
Directory of Open Access Journals (Sweden)
Han Bang-Xian
2017-08-01
Full Text Available The goal of the paper is to study the angle between two curves in the framework of metric (and metric measure spaces. More precisely, we give a new notion of angle between two curves in a metric space. Such a notion has a natural interplay with optimal transportation and is particularly well suited for metric measure spaces satisfying the curvature-dimension condition. Indeed one of the main results is the validity of the cosine formula on RCD*(K, N metric measure spaces. As a consequence, the new introduced notions are compatible with the corresponding classical ones for Riemannian manifolds, Ricci limit spaces and Alexandrov spaces.
Strange Curves, Counting Rabbits, & Other Mathematical Explorations
Ball, Keith
2011-01-01
How does mathematics enable us to send pictures from space back to Earth? Where does the bell-shaped curve come from? Why do you need only 23 people in a room for a 50/50 chance of two of them sharing the same birthday? In Strange Curves, Counting Rabbits, and Other Mathematical Explorations, Keith Ball highlights how ideas, mostly from pure math, can answer these questions and many more. Drawing on areas of mathematics from probability theory, number theory, and geometry, he explores a wide range of concepts, some more light-hearted, others central to the development of the field and used dai
Timelike curves can increase entanglement with LOCC
Moulick, Subhayan Roy; Panigrahi, Prasanta K.
2016-11-01
We study the nature of entanglement in presence of Deutschian closed timelike curves (D-CTCs) and open timelike curves (OTCs) and find that existence of such physical systems in nature would allow us to increase entanglement using local operations and classical communication (LOCC). This is otherwise in direct contradiction with the fundamental definition of entanglement. We study this problem from the perspective of Bell state discrimination, and show how D-CTCs and OTCs can unambiguously distinguish between four Bell states with LOCC, that is otherwise known to be impossible.
Direct stigmatic imaging with curved surfaces.
Courtial, Johannes; Oxburgh, Stephen; Tyc, Tomáš
2015-03-01
We study the possibilities of direct (using one intersection with each light ray) stigmatic imaging with a curved surface that can change ray directions in an arbitrary way. By purely geometric arguments we show that the only possible case of such imaging is the trivial one where the image of any point is identical to the point itself and the surface does not perform any change of the ray direction at all. We also discuss an example of a curved surface which performs indirect stigmatic imaging after twice intersecting each light ray.
Wind Turbine Power Curves Incorporating Turbulence Intensity
DEFF Research Database (Denmark)
Sørensen, Emil Hedevang Lohse
2014-01-01
The performance of a wind turbine in terms of power production (the power curve) is important to the wind energy industry. The current IEC-61400-12-1 standard for power curve evaluation recognizes only the mean wind speed at hub height and the air density as relevant to the power production....... However, numerous studies have shown that the power production depends on several variables, in particular turbulence intensity. This paper presents a model and a method that are computationally tractable and able to account for some of the influence of turbulence intensity on the power production...
On Clifford's theorem for singular curves
Franciosi, Marco
2011-01-01
Let C be a 2-connected Gorenstein curve either reduced or contained in a smooth algebraic surface and let S be a subcanonical cluster (i.e. a 0-dim scheme such that the space H^0(C, I_S K_C) contains a generically invertible section). Under some general assumptions on S or C we show that h^0(C, I_S K_C) <= p_a(C) - deg (S)/2 and if equality holds then either S is trivial, or C is honestly hyperelliptic or 3-disconnected. As a corollary we give a generalization of Clifford's theorem for reduced curves.
Topological Field Theory and Rational Curves
Aspinwall, Paul S; Aspinwall, Paul S.; Morrison, David R.
1993-01-01
We analyze the superstring propagating on a Calabi-Yau threefold. This theory naturally leads to the consideration of Witten's topological non-linear sigma-model and the structure of rational curves on the Calabi-Yau manifold. We study in detail the case of the world-sheet of the string being mapped to a multiple cover of an isolated rational curve and we show that a natural compactification of the moduli space of such a multiple cover leads to a formula in agreement with a conjecture by Candelas, de la Ossa, Green and Parkes.
Charged particles constrained to a curved surface
Müller, Thomas
2012-01-01
We study the motion of charged particles constrained to arbitrary two-dimensional curved surfaces but interacting in three-dimensional space via the Coulomb potential. To speed-up the interaction calculations, we use the parallel compute capability of the Compute Unified Device Architecture (CUDA) of todays graphics boards. The particles and the curved surfaces are shown using the Open Graphics Library (OpenGL). The paper is intended to give graduate students, who have basic experiences with electrostatics and differential geometry, a deeper understanding in charged particle interactions and a short introduction how to handle a many particle system using parallel computing on a single home computer
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.
Han, Jie; Casey, Tiernan A; Bisetti, Fabrizio; Im, Hong G; Chen, Jyh-Yuan
2016-01-01
The i-V curve describes the current drawn from a flame as a function of the voltage difference applied across the reaction zone. Since combustion diagnostics and flame control strategies based on electric fields depend on the amount of current drawn from flames, there is significant interest in modeling and understanding i-V curves. We implement and apply a detailed model for the simulation of the production and transport of ions and electrons in one dimensional premixed flames. An analytical reduced model is developed based on the detailed one, and analytical expressions are used to gain insight into the characteristics of the i-V curve for various flame configurations. In order for the reduced model to capture the spatial distribution of the electric field accurately, the concept of a dead zone region, where voltage is constant, is introduced, and a suitable closure for the spatial extent of the dead zone is proposed and validated. The results from the reduced modeling framework are found to be in good agre...
Wavelet subdivision methods gems for rendering curves and surfaces
Chui, Charles
2010-01-01
OVERVIEW Curve representation and drawing Free-form parametric curves From subdivision to basis functions Wavelet subdivision and editing Surface subdivision BASIS FUNCTIONS FOR CURVE REPRESENTATION Refinability and scaling functions Generation of smooth basis functions Cardinal B-splines Stable bases for integer-shift spaces Splines and polynomial reproduction CURVE SUBDIVISION SCHEMES Subdivision matrices and stencils B-spline subdivision schemes Closed curve rendering Open curve rendering BASIS FUNCTIONS GENERATED BY SUBDIVISION MATRICES Subdivision operators The up-sampling convolution ope
On Addition Formulae for Sigma Functions of Telescopic Curves
Directory of Open Access Journals (Sweden)
Takanori Ayano
2013-06-01
Full Text Available A telescopic curve is a certain algebraic curve defined by m−1 equations in the affine space of dimension m, which can be a hyperelliptic curve and an (n,s curve as a special case. We extend the addition formulae for sigma functions of (n,s curves to those of telescopic curves. The expression of the prime form in terms of the derivative of the sigma function is also given.
CONSTRUCTION OF G2 CONTINUOUS CURVES ON SURFACE WITH PLANAR CUBIC B(E)ZIER CURVES
Institute of Scientific and Technical Information of China (English)
Wang Xiaoping; Zhang Weizhong; Zhang Liyan; Zhou Rurong
2005-01-01
The problem of constructing curve on parametric surface (or surface that can be parameterized) such that it interpolates a sequence of points with prescribed tangent direction and curvature vector (or geodesic curvature) at every point and the issue of curve blending on this kind of surface are researched. The mapping and tangent mapping from the surface to its parametric plane are introduced and thus several conclusions with differential geometry are deduced. Based on those conclusions, the problem of interpolating (or blending) curve on a parametric surface is converted to a similar one on its parametric plane. The final solution curve of either interpolation or blending issue is explicit and can still be expressed by parametric form. And so, unlike existing methods, the presented method needs not to use any surface/surface intersection algorithms, usually a troublesome process, for displaying such interpolation curve. Experiment results show the presented methods are feasible and applicable to CAD/CAM and computer graphics.
On Correlated-noise Analyses Applied to Exoplanet Light Curves
Cubillos, Patricio; Harrington, Joseph; Loredo, Thomas J.; Lust, Nate B.; Blecic, Jasmina; Stemm, Madison
2017-01-01
Time-correlated noise is a significant source of uncertainty when modeling exoplanet light-curve data. A correct assessment of correlated noise is fundamental to determine the true statistical significance of our findings. Here, we review three of the most widely used correlated-noise estimators in the exoplanet field, the time-averaging, residual-permutation, and wavelet-likelihood methods. We argue that the residual-permutation method is unsound in estimating the uncertainty of parameter estimates. We thus recommend to refrain from this method altogether. We characterize the behavior of the time averaging’s rms-versus-bin-size curves at bin sizes similar to the total observation duration, which may lead to underestimated uncertainties. For the wavelet-likelihood method, we note errors in the published equations and provide a list of corrections. We further assess the performance of these techniques by injecting and retrieving eclipse signals into synthetic and real Spitzer light curves, analyzing the results in terms of the relative-accuracy and coverage-fraction statistics. Both the time-averaging and wavelet-likelihood methods significantly improve the estimate of the eclipse depth over a white-noise analysis (a Markov-chain Monte Carlo exploration assuming uncorrelated noise). However, the corrections are not perfect when retrieving the eclipse depth from Spitzer data sets, these methods covered the true (injected) depth within the 68% credible region in only ˜45%-65% of the trials. Lastly, we present our open-source model-fitting tool, Multi-Core Markov-Chain Monte Carlo (MC3). This package uses Bayesian statistics to estimate the best-fitting values and the credible regions for the parameters for a (user-provided) model. MC3 is a Python/C code, available at https://github.com/pcubillos/MCcubed.
Remote sensing used for power curves
DEFF Research Database (Denmark)
Wagner, Rozenn; Ejsing Jørgensen, Hans; Schmidt Paulsen, Uwe
2008-01-01
Power curve measurement for large wind turbines requires taking into account more parameters than only the wind speed at hub height. Based on results from aerodynamic simulations, an equivalent wind speed taking the wind shear into account was defined and found to reduce the power standard deviat...
Polynomial Interpolation in the Elliptic Curve Cryptosystem
Directory of Open Access Journals (Sweden)
Liew K. Jie
2011-01-01
Full Text Available Problem statement: In this research, we incorporate the polynomial interpolation method in the discrete logarithm problem based cryptosystem which is the elliptic curve cryptosystem. Approach: In this study, the polynomial interpolation method to be focused is the Lagrange polynomial interpolation which is the simplest polynomial interpolation method. This method will be incorporated in the encryption algorithm of the elliptic curve ElGamal cryptosystem. Results: The scheme modifies the elliptic curve ElGamal cryptosystem by adding few steps in the encryption algorithm. Two polynomials are constructed based on the encrypted points using Lagrange polynomial interpolation and encrypted for the second time using the proposed encryption method. We believe it is safe from the theoretical side as it still relies on the discrete logarithm problem of the elliptic curve. Conclusion/Recommendations: The modified scheme is expected to be more secure than the existing scheme as it offers double encryption techniques. On top of the existing encryption algorithm, we managed to encrypt one more time using the polynomial interpolation method. We also have provided detail examples based on the described algorithm.
Nonlinear Growth Curves in Developmental Research
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…
Marginal Utility and Convex Indifference Curves.
Jackson, A.A.
1981-01-01
Reviews discussion of the relationship between marginal utility and indifference curves which has been presented in recent issues of "Economics." Concludes that indifference analysis does not embody the assumptions of marginal utility theory and that there is no simple relationship between these concepts that does not entail unacceptable…
The fundamental group of an algebraic curve
Jong, Johan de; Oort, F.
2001-01-01
Seminar on Algebraic Geometry, MIT 2002 In this seminar we study geometric properties of algebraic curves, or of Riemann surfaces. with the help of an algebraic object attached: the fundamental group, either the algebraic fundamental group, as introduced by Grothendieck, or the topological fundamen
Theoretical Magnon Dispersion Curves for Gd
DEFF Research Database (Denmark)
Lindgård, Per-Anker; Harmon, B. N.; Freeman, A. J.
1975-01-01
The magnon dispersion curve of Gd metal has been determined from first principles by use of augmented-plane-wave energy bands and wave functions. The exchange matrix elements I(k⃗, k⃗′) between the 4f electrons and the conduction electrons from the first six energy bands were calculated under...
ATLAS detector records its first curved muon
2007-01-01
The barrel muon spectrometer of the ATLAS detector has acquired its first cosmic event in a magnetic field produced by the barrel toroid magnet. This was an important test of the chambers in their final configurations, and marked the first triggering and measurement of curved cosmic ray muons in ATLAS.
CURIE-TEMPERATURE "SLATER-PAULING CURVE"
Kakehashi, Y.; Hosohata, O.
1988-01-01
The systematic variation of the Curie-temperature "Slater-Pauling curve" has been explained for the first time on the basis of the finite-temperature theory of the local environment effect. The peculiarity of the Curie temperatures in Fe-V, Fe-Ni, and Ni-Mn alloys is elucidated by using the effective exchange couplings.
Packing Superballs from Codes and Algebraic Curves
Institute of Scientific and Technical Information of China (English)
Li LIU; Chao Ping XING
2008-01-01
In the present paper, we make use of codes with good parameters and algebraic curves over finite fields with many rational points to construct dense packings of superballs. It turns out that our packing density is quite reasonable. In particular, we improve some values for the best-known lower bounds on packing density.
Growth Curves for Girls with Turner Syndrome
Bertapelli, Fabio; Barros-Filho, Antonio de Azevedo; Antonio, Maria Ângela Reis de Góes Monteiro; Barbeta, Camila Justino de Oliveira; de Lemos-Marini, Sofia Helena Valente
2014-01-01
The objective of this study was to review the growth curves for Turner syndrome, evaluate the methodological and statistical quality, and suggest potential growth curves for clinical practice guidelines. The search was carried out in the databases Medline and Embase. Of 1006 references identified, 15 were included. Studies constructed curves for weight, height, weight/height, body mass index, head circumference, height velocity, leg length, and sitting height. The sample ranged between 47 and 1,565 (total = 6,273) girls aged 0 to 24 y, born between 1950 and 2006. The number of measures ranged from 580 to 9,011 (total = 28,915). Most studies showed strengths such as sample size, exclusion of the use of growth hormone and androgen, and analysis of confounding variables. However, the growth curves were restricted to height, lack of information about selection bias, limited distributional properties, and smoothing aspects. In conclusion, we observe the need to construct an international growth reference for girls with Turner syndrome, in order to provide support for clinical practice guidelines. PMID:24949463
Electron conductance in curved quantum structures
DEFF Research Database (Denmark)
Willatzen, Morten; Gravesen, Jens
2010-01-01
A differential-geometry analysis is employed to investigate the transmission of electrons through a curved quantum-wire structure. Although the problem is a three-dimensional spatial problem, the Schrodinger equation can be separated into three general coordinates. Hence, the proposed method...
Developing laminar flow in curved rectangular channels
De Vriend, H.J.
1978-01-01
As an intermediate step between earlier investigations on fully developed laminar flow in curved channels of shallow rectancular wet cross-section and the mathematical modeling of turbulent flow in river bends, a mathematical model of developing laminar flow in such channels is investigated. The mos
Picard groups of differential operators on curves
Wilson, George
2010-01-01
Let X be a complex affine curve (not isomorphic to the affine line), and let Pic(D) be the group of autoequivalences of the category of D(X)-modules. Cannings and Holland have shown that Pic(D) fits into an exact sequence in which the other groups can be considered known: we show that this sequence is split.
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.
Affine LIBOR Models with Multiple Curves
DEFF Research Database (Denmark)
Grbac, Zorana; Papapantoleon, Antonis; Schoenmakers, John
2015-01-01
We introduce a multiple curve framework that combines tractable dynamics and semianalytic pricing formulas with positive interest rates and basis spreads. Negative rates and positive spreads can also be accommodated in this framework. The dynamics of overnight indexed swap and LIBOR rates...... with dependent LIBOR rates is developed that allows for an efficient and accurate calibration to a system of caplet prices....
Is the Water Heating Curve as Described?
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…
Pseudorandom Bits From Points on Elliptic Curves
Farashahi, Reza R
2010-01-01
Let $\\E$ be an elliptic curve over a finite field $\\F_{q}$ of $q$ elements, with $\\gcd(q,6)=1$, given by an affine Weierstra\\ss\\ equation. We also use $x(P)$ to denote the $x$-component of a point $P = (x(P),y(P))\\in \\E$. We estimate character sums of the form
Principal normal indicatrices of closed space curves
DEFF Research Database (Denmark)
Røgen, Peter
1999-01-01
A theorem due to J. Weiner, which is also proven by B. Solomon, implies that a principal normal indicatrix of a closed space curve with nonvanishing curvature has integrated geodesic curvature zero and contains no subarc with integrated geodesic curvature pi. We prove that the inverse problem alw...
Least-squares fitting Gompertz curve
Jukic, Dragan; Kralik, Gordana; Scitovski, Rudolf
2004-08-01
In this paper we consider the least-squares (LS) fitting of the Gompertz curve to the given nonconstant data (pi,ti,yi), i=1,...,m, m≥3. We give necessary and sufficient conditions which guarantee the existence of the LS estimate, suggest a choice of a good initial approximation and give some numerical examples.
INITIAL SLOPE OF THE HYSTERESIS CURVE
Gerritsma, G.J.; Stam, M.T.H.C.W.; Lodder, J. C.; Popma, Th.J.A.
1988-01-01
An analytical expression for the initial slope T of the hysteresis curve is derived for a stripe domain structure in a thin magnetic film, giving that T-1 is proportional to t-1/2 (t = film thickness). This is confirmed by measurements on RF sputtered CoCr films with 20 nm ≤ t ≤ 950 nm.
Initial slope of the hysteresis curve
Gerritsma, G.J.; Stam, M.T.H.C.W.; Lodder, J.C.; Popma, Th.J.A.
1988-01-01
An analytical expression for the initial slope T of the hysteresis curve is derived for a stripe domain structure in a thin magnetic film, giving that T-1 is proportional to t-1/2 (t = film thickness). This is confirmed by measurements on RF sputtered CoCr films with 20 nm £ t £ 950 nm.
Growth Curves for Girls with Turner Syndrome
Directory of Open Access Journals (Sweden)
Fabio Bertapelli
2014-01-01
Full Text Available The objective of this study was to review the growth curves for Turner syndrome, evaluate the methodological and statistical quality, and suggest potential growth curves for clinical practice guidelines. The search was carried out in the databases Medline and Embase. Of 1006 references identified, 15 were included. Studies constructed curves for weight, height, weight/height, body mass index, head circumference, height velocity, leg length, and sitting height. The sample ranged between 47 and 1,565 (total = 6,273 girls aged 0 to 24 y, born between 1950 and 2006. The number of measures ranged from 580 to 9,011 (total = 28,915. Most studies showed strengths such as sample size, exclusion of the use of growth hormone and androgen, and analysis of confounding variables. However, the growth curves were restricted to height, lack of information about selection bias, limited distributional properties, and smoothing aspects. In conclusion, we observe the need to construct an international growth reference for girls with Turner syndrome, in order to provide support for clinical practice guidelines.
A curved flume bed-load experiment
Talmon, A.M.; Marsman, E.R.A.
1988-01-01
In this report the results of a bed-load experiment in a curved flume are presented. The experiments have been carried out in the Laboratory of Fluid Mechanics (L.F.M.) at the Delft University of Technology. The main object of the experiments is to develop and to test data-acquisition procedures for
Curving Yang-Mills-Higgs Gauge Theories
Kotov, Alexei
2015-01-01
Established fundamental physics can be described by fields, which are maps. The source of such a map is space-time, which can be curved due to gravity. The map itself needs to be curved in its gauge field part so as to describe interaction forces like those mediated by photons and gluons. In the present article, we permit non-zero curvature also on the internal space, the target of the field map. The action functional and the symmetries are constructed in such a way that they reduce to those of standard Yang-Mills-Higgs (YMH) gauge theories precisely when the curvature on the target of the fields is turned off. For curved targets one obtains a new theory, a curved YMH gauge theory. It realizes in a mathematically consistent manner an old wish in the community: replacing structures constants by functions depending on the scalars of the theory. In addition, we provide a simple 4d toy model, where the gauge symmetry is abelian, but turning off the gauge fields, no rigid symmetry remains---another possible manife...
The Rees Algebra for Certain Monomial Curves
Mukhopadhyay, Debasish
2010-01-01
In this article, we find the equations defining the Rees algebra for certain Monomial Curves explicitly and use them to prove that the blowup scheme is not smooth. This proves a conjecture of Francia in affirmative, which says that a dimension one prime in a regular local ring is a complete intersection if it has a smooth blowup.
BIPERIODIC FIBONACCI WORD AND ITS FRACTAL CURVE
Directory of Open Access Journals (Sweden)
José Luis Ramírez
2015-02-01
Full Text Available In this paper, we introduce a word-combinatorial interpretation of the biperiodic Fibonacci sequence. We study some properties of this new family of infinite words. Moreover, we associate to this family of words a family of curves with interesting patterns.
Tempo curves considered harmful (part 1)
Desain, P.; Honing, H.
1991-01-01
A column (the first of a series of three) constitutes an abridged and adapted version of Tempo curves considered harmful . Two friends, an amateur mathematician (M) and a would-be psychologist (P), invited a retired pianist to do some experiments with their new sequencer program. As musical material
Tempo curves considered harmful (part 2)
Desain, P.; Honing, H.
1991-01-01
A column (the second of a series of three) constitutes an abridged and adapted version of Tempo curves considered harmful . M (an amateur mathematician) and P (a would-be psychologist) incorporated some generative models for expressive timing in their sequencer program. This proved partially succesf
TELECOMMUNICATIONS INFRASTRUCTURE AND GDP /JIPP CURVE/
Directory of Open Access Journals (Sweden)
Mariana Kaneva
2016-07-01
Full Text Available The relationship between telecommunications infrastructure and economic activity is under discussion in many scientific papers. Most of the authors use for research and analysis the Jipp curve. A lot of doubts about the correctness of the Jipp curve appear in terms of applying econometric models. The aim of this study is a review of the Jipp curve, refining the possibility of its application in modern conditions. The methodology used in the study is based on dynamic econometric models, including tests for nonstationarity and tests for causality. The focus of this study is directed to methodological problems in measuring the local density types of telecommunication networks. This study offers a specific methodology for assessing the Jipp law, through VAR-approach and Granger causality tests. It is proved that mechanical substitution of momentary aggregated variables (such as the number of subscribers of a telecommunication network at the end of the year and periodically aggregated variables (such as GDP per capita in the Jipp�s curve is methodologically wrong. Researchers have to reconsider the relationship set in the Jipp�s curve by including additional variables that characterize the Telecommunications sector and the economic activity in a particular country within a specified time period. GDP per capita should not be regarded as a single factor for the local density of telecommunications infrastructure. New econometric models studying the relationship between the investments in telecommunications infrastructure and economic development may be not only linear regression models, but also other econometric models. New econometric models should be proposed after testing and validating with sound economic theory and econometric methodology.
Modeling and Fitting Exoplanet Transit Light Curves
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
Modeling the impact of spatial relationships on horizontal curve safety.
Findley, Daniel J; Hummer, Joseph E; Rasdorf, William; Zegeer, Charles V; Fowler, Tyler J
2012-03-01
The curved segments of roadways are more hazardous because of the additional centripetalforces exerted on a vehicle, driver expectations, and other factors. The safety of a curve is dependent on various factors, most notably by geometric factors, but the location of a curve in relation to other curves is also thought to influence the safety of those curves because of a driver's expectation to encounter additional curves. The link between an individual curve's geometric characteristics and its safety performance has been established, but spatial considerations are typically not included in a safety analysis. The spatial considerations included in this research consisted of four components: distance to adjacent curves, direction of turn of the adjacent curves, and radius and length of the adjacent curves. The primary objective of this paper is to quantify the spatial relationship between adjacent horizontal curves and horizontal curve safety using a crash modification factor. Doing so enables a safety professional to more accurately estimate safety to allocate funding to reduce or prevent future collisions and more efficiently design new roadway sections to minimize crash risk where there will be a series of curves along a route. The most important finding from this research is the statistical significance of spatial considerations for the prediction of horizontal curve safety. The distances to adjacent curves were found to be a reliable predictor of observed collisions. This research recommends a model which utilizes spatial considerations for horizontal curve safety prediction in addition to current Highway Safety Manual prediction capabilities using individual curve geometric features.
The arctic curve of the domain-wall six-vertex model in its anti-ferroelectric regime
Colomo, F; Zinn-Justin, P
2010-01-01
An explicit expression for the spatial curve separating the region of ferroelectric order (`frozen' zone) from the disordered one (`temperate' zone) in the six-vertex model with domain wall boundary conditions in its anti-ferroelectric regime is obtained.
A new methodology for free wake analysis using curved vortex elements
Bliss, Donald B.; Teske, Milton E.; Quackenbush, Todd R.
1987-01-01
A method using curved vortex elements was developed for helicopter rotor free wake calculations. The Basic Curve Vortex Element (BCVE) is derived from the approximate Biot-Savart integration for a parabolic arc filament. When used in conjunction with a scheme to fit the elements along a vortex filament contour, this method has a significant advantage in overall accuracy and efficiency when compared to the traditional straight-line element approach. A theoretical and numerical analysis shows that free wake flows involving close interactions between filaments should utilize curved vortex elements in order to guarantee a consistent level of accuracy. The curved element method was implemented into a forward flight free wake analysis, featuring an adaptive far wake model that utilizes free wake information to extend the vortex filaments beyond the free wake regions. The curved vortex element free wake, coupled with this far wake model, exhibited rapid convergence, even in regions where the free wake and far wake turns are interlaced. Sample calculations are presented for tip vortex motion at various advance ratios for single and multiple blade rotors. Cross-flow plots reveal that the overall downstream wake flow resembles a trailing vortex pair. A preliminary assessment shows that the rotor downwash field is insensitive to element size, even for relatively large curved elements.
The arctic curve of the domain-wall six-vertex model
Colomo, F
2009-01-01
The problem of the form of the `arctic' curve of the six-vertex model with domain wall boundary conditions in its disordered regime is addressed. It is well-known that in the scaling limit the model exhibits phase-separation, with regions of order and disorder sharply separated by a smooth curve, called the arctic curve. To find this curve, we study a multiple integral representation for the emptiness formation probability, a correlation function devised to detect spatial transition from order to disorder. We conjecture that the arctic curve, for arbitrary choice of the vertex weights, can be characterized by the condition of condensation of almost all roots of the corresponding saddle-point equations at the same, known, value. In explicit calculations we restrict to the disordered regime for which we have been able to compute the scaling limit of certain generating function entering the saddle-point equations. The arctic curve is obtained in parametric form and appears to be a non-algebraic curve in general;...
Shape modification of Bézier curves by constrained optimization
Institute of Scientific and Technical Information of China (English)
WU Qing-biao; XIA Fei-hai
2005-01-01
The Bézier curve is one of the most commonly used parametric curves in CAGD and Computer Graphics and has many portant problem, and is also an important research issue in CAD/CAM and NC technology fields. This work investigates the curves to satisfy the given constraints and modify the shape of the curves optimally. Practical examples are also given.
Chun, Sehun
2012-01-01
In cardiac electrophysiology, it is important to predict the necessary conditions for conduction failure, the failure of the cardiac excitation propagation even in the presence of normal excitable tissue, in high-dimensional anisotropic space because these conditions may provide feasible mechanisms for abnormal excitation propagations such as atrial re-entry and, subsequently, atrial fibrillation even without taking into account the time-dependent refractory region. Some conditions of conduction failure have been studied for anisotropy or simple curved surfaces, but the general conditions on anisotropic curved surfaces (anisotropic and curved surface) remain unknown. To predict and analyze conduction failure on anisotropic curved surfaces, a new analytic approach is proposed, called the relative acceleration approach borrowed from spacetime physics. Motivated by a discrete model of cardiac excitation propagation, this approach is based on the hypothesis that a large relative acceleration can translate to a dr...
Spatial and Temporal Variations of Light Curves in Gravitationally Lensed Sources
Minakov, A A
2004-01-01
Effects of macro-and microlensing on the spatial and temporal characteristics of images of remote sources, observed through the inner regions of lensing galaxies are discussed. A particular attention was given to the case, when microlenses, - stars, star-like or planetary bodies, - are situated near the critical curves of macrolenses, - galaxies, stellar clusters, etc. The investigation is of interest for the gravitational lens (GL) systems, where the lensed images are observed close to the critical curve of a macrolens. Annular, arched or confluent images should be regarded as an indication to such a proximity. Numerical simulation allowed to determine the structure of critical curves and caustics, formed by macro and microlenses, and to evaluate possible distortions, caused by microlenses for various locations with respect to the critical curve of a regular lens. The difference of our results from those obtained earlier with the standard (linearized) approach to describe the regular gravitational lens was s...
Simultaneous Modelling of the Complete SN1993J Expansion and Radio Light Curves
Martí-Vidal, I.; Marcaide, J. M.; Alberdi, A.
We report on our modelling of all the available VLBI data and radio light curves of supernova SN1993J. We have used the most complete expansion curve of a supernova ever, which spans more than a decade at several frequencies. For the data modelling, we have developed a new software capable of simulating the evolution of the radio emission of a supernova. We find that for explaining both the radio light curves and the expansion curve simultaneously, a radial structure of the magnetic field inside the radiating region and opacity effects from the ejected material have to be considered, together with a constant pre-supernova mass-loss rate (contrary to some results found by other authors).
Formation and evolution of blue compact dwarfs: The origin of their steep rotation curves
Watts, A
2016-01-01
The origin of the observed steep rotation curves of blue compact dwarf galaxies (BCDs) remains largely unexplained by theoretical models of BCD formation. We therefore investigate the rotation curves in BCDs formed from mergers between gas- rich dwarf irregular galaxies based on the results of numerical simulations for BCD formation. The principal results are as follows. The dark matter of merging dwarf irregulars undergoes a central concentration so that the central density can become up to 6 times higher than those of the initial dwarf irregulars. However, the more compact dark matter halo alone can not reproduce the gradient differences observed between dwarf irregulars and BCDs. We provide further support that the central concentration of gas due to rapid gas-transfer to the central regions of dwarf-dwarf mergers is responsible for the observed difference in rotation curve gradients. The BCDs with central gas concentration formed from merging can thus show steeply rising rotation curves in their central r...
Numerical Investigation of the Unsteady Flow in a Transonic Compressor with Curved Rotors
Institute of Scientific and Technical Information of China (English)
Mao Mingming; Song Yanping; Wang Zhongqi
2008-01-01
The unsteady 3D flow fields in a single-stage transonic compressor under designed conditions are simulated numerically to inves- tigate the effects of the curved rotors on the stage performance and the aerodynamic interaction between the blade rows. The results show that, compared to the compressor with un-curved rotors, the compressor under scrutiny acquires remarkable increases in efficiency with significantly reduced amplitudes of the time-dependent fluctuation. The amplitude of the pressure fluctuation around the stator leading edge decreases at both endwalls, but increases at the mid-span in the curved rotors. The pressure fluctuation near the stator lead- ing edge, therefore, becomes more uniform in the radial direction of this compressor. Except for the leading edge area, the pressure fluc- tuation amplitude declines remarkably in the tip region of stator surface downstream of the curved rotor, but hardly changes in the mid- dle and at the hub.
On quadratic residue codes and hyperelliptic curves
Directory of Open Access Journals (Sweden)
David Joyner
2008-01-01
Full Text Available For an odd prime p and each non-empty subset S⊂GF(p, consider the hyperelliptic curve X S defined by y 2 =f S (x, where f S (x = ∏ a∈S (x-a. Using a connection between binary quadratic residue codes and hyperelliptic curves over GF(p, this paper investigates how coding theory bounds give rise to bounds such as the following example: for all sufficiently large primes p there exists a subset S⊂GF(p for which the bound |X S (GF(p| > 1.39p holds. We also use the quasi-quadratic residue codes defined below to construct an example of a formally self-dual optimal code whose zeta function does not satisfy the ``Riemann hypothesis.''
THE FLOW IN ROTATING CURVED CIRCULAR PIPE
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
The combined effects of the system rotation (Coriolis force) and curvature (centrifugal force) on the flow in rotating curved circular pipe with small curvature are examined by perturbation method. A second-order perturbation solution is presented. The secondary flow structure and the primary axial velocity distributions are studied in detail. The loops of the secondary flow are more complex than those in a curved pipe without rotation or a rotating straight pipe. Its numbers depend on the body force ratio F which represents the ratio of the Coriolis to the centrifugal force. The maximum of the axial velocity is pushed to either outer bend or inner bend, which is also determined by F. The results are confirmed by the results of other authors who studied the same problem by different methods.
From Smooth Curves to Universal Metrics
Gurses, Metin; Tekin, Bayram
2016-01-01
A special class of metrics, called universal metrics, solve all gravity theories defined by covariant field equations purely based on the metric tensor. Since we currently lack the knowledge of what the full of quantum corrected field equations of gravity are at a given microscopic length scale, these metrics are particularly important in understanding quantum fields in curved backgrounds in a consistent way. But, finding explicit universal metrics has been a hard problem as there does not seem to be a procedure for it. In this work, we overcome this difficulty and give a construction of universal metrics of d dimensional spacetime from curves constrained to live in a d-1 dimensional Minkowski spacetime or a Euclidean space.
Minimax hypothesis testing for curve registration
Collier, Olivier
2011-01-01
This paper is concerned with the problem of goodness-of-fit for curve registration, and more precisely for the shifted curve model, whose application field reaches from computer vision and road traffic prediction to medicine. We give bounds for the asymptotic minimax separation rate, when the functions in the alternative lie in Sobolev balls and the separation from the null hypothesis is measured by the l2-norm. We use the generalized likelihood ratio to build a nonadaptive procedure depending on a tuning parameter, which we choose in an optimal way according to the smoothness of the ambient space. Then, a Bonferroni procedure is applied to give an adaptive test over a range of Sobolev balls. Both achieve the asymptotic minimax separation rates, up to possible logarithmic factors.
Point- and curve-based geometric conflation
López-Vázquez, C.
2013-01-01
Geometric conflation is the process undertaken to modify the coordinates of features in dataset A in order to match corresponding ones in dataset B. The overwhelming majority of the literature considers the use of points as features to define the transformation. In this article we present a procedure to consider one-dimensional curves also, which are commonly available as Global Navigation Satellite System (GNSS) tracks, routes, coastlines, and so on, in order to define the estimate of the displacements to be applied to each object in A. The procedure involves three steps, including the partial matching of corresponding curves, the computation of some analytical expression, and the addition of a correction term in order to satisfy basic cartographic rules. A numerical example is presented. © 2013 Copyright Taylor and Francis Group, LLC.
Physical and Stable Closed Timelike Curves
Ho, Chiu Man
2012-01-01
We construct a class of closed timelike curves (CTCs) using a compactified extra dimension $u$. A nonzero metric element $g_{tu}(u)$ enables particles to travel backwards in global time $t$. The compactified dimension guarantees that the geodesic curve closes in $u$. The effective 2D ($t$ and $u$) nature of the metric ensures that spacetime is flat, therein satisfying all the classical stability conditions as expressed by the energy conditions. Finally, stationarity of the metric guarantees that a particle's energy is conserved. The pathologies that plague many hypothesized metrics admitting CTCs, e.g. an infinite cylinder of matter, a negative energy-distribution, particle acceleration/blue-shifting along the CTC, do not occur within our metric class.
Local neighborliness of the symmetric moment curve
Lee, Seung Jin
2011-01-01
A centrally symmetric analogue of the cyclic polytope, the bicyclic polytope, was defined in [BN08]. The bicyclic polytope is defined by the convex hull of finitely many points on the symmetric moment curve where the set of points has a symmetry about the origin. In this paper, we study the Barvinok-Novik orbitope, the convex hull of the symmetric moment curve. It was proven in [BN08] that the orbitope is locally $k$-neighborly, that is, the convex hull of any set of $k$ distinct points on an arc of length not exceeding $\\phi_k$ in $\\mathbb{S}^1$ is a $(k-1)$-dimensional face of the orbitope for some positive constant $\\phi_k$. We prove that we can choose $\\phi_k $ bigger than $\\gamma k^{-3/2} $ for some positive constant $\\gamma$.
Light Curves of Rapidly Rotating Neutron Stars
Braje, T M; Rauch, K P; Braje, Timothy M.; Romani, Roger W.; Rauch, Kevin P.
2000-01-01
We consider the effect of rapid rotation on the light curves of neutron stars with hot polar caps. For $P \\approx 3$ms spin periods, the pulse fractions can be as much as an order of magnitude larger than with simple slowly-rotating (Schwarzschild) estimates. Doppler boosting, in particular, leads to characteristic distortion and ``soft lags'' in the pulse profiles, which are easily measurable in light curves with moderate energy resolution. With $\\sim 10^5$ photons it should also be possible to isolate the more subtle distortions of light travel time variations and frame dragging. Detailed analysis of high quality millisecond pulsar data from upcoming X-ray missions must include these effects.
Chiral fermions on 2D curved spacetimes
Loran, Farhang
2016-01-01
The theory of free Majorana-Weyl spinors is the prototype of conformal field theory in two dimensions in which the gravitational anomaly and the Weyl anomaly obstruct extending the flat spacetime results to curved backgrounds. In this paper, we investigate a quantization scheme in which the short distance singularity in the two-point function of chiral fermions on a two dimensional curved spacetime is given by the Green's function corresponding to the classical field equation. We compute the singular term in the Green's function explicitly and observe that the short distance limit is not well-defined in general. We identify constraints on the geometry which are necessary to resolve this problem. On such special backgrounds the theory has locally $c=\\frac{1}{2}$ conformal symmetry.
From smooth curves to universal metrics
Gürses, Metin; Şişman, Tahsin ćaǧrı; Tekin, Bayram
2016-08-01
A special class of metrics, called universal metrics, solves all gravity theories defined by covariant field equations purely based on the metric tensor. Since we currently lack the knowledge of what the full quantum-corrected field equations of gravity are at a given microscopic length scale, these metrics are particularly important in understanding quantum fields in curved backgrounds in a consistent way. However, finding explicit universal metrics has been a difficult problem as there does not seem to be a procedure for it. In this work, we overcome this difficulty and give a construction of universal metrics of d -dimensional spacetime from curves constrained to live in a (d -1 )-dimensional Minkowski spacetime or a Euclidean space.
Field Theory on Curved Noncommutative Spacetimes
Directory of Open Access Journals (Sweden)
Alexander Schenkel
2010-08-01
Full Text Available We study classical scalar field theories on noncommutative curved spacetimes. Following the approach of Wess et al. [Classical Quantum Gravity 22 (2005, 3511 and Classical Quantum Gravity 23 (2006, 1883], we describe noncommutative spacetimes by using (Abelian Drinfel'd twists and the associated *-products and *-differential geometry. In particular, we allow for position dependent noncommutativity and do not restrict ourselves to the Moyal-Weyl deformation. We construct action functionals for real scalar fields on noncommutative curved spacetimes, and derive the corresponding deformed wave equations. We provide explicit examples of deformed Klein-Gordon operators for noncommutative Minkowski, de Sitter, Schwarzschild and Randall-Sundrum spacetimes, which solve the noncommutative Einstein equations. We study the construction of deformed Green's functions and provide a diagrammatic approach for their perturbative calculation. The leading noncommutative corrections to the Green's functions for our examples are derived.
Recombination Effects on Supernovae Light-Curves
Goldfriend, Tomer; Sari, Re'em
2014-01-01
Supernovae of type IIP are marked by the long plateau seen in their optical light curves. The plateau is believed to be the result of a recombination wave that propagates through the outflowing massive hydrogen envelope. Here, we analytically investigate the transition from a fully ionized envelope to a partially recombined one and its effects on the SN light curve. The motivation is to establish the underlying processes which dominate the evolution at late times when recombination takes place in the envelope, yet early enough so that $^{56}$Ni decay is a negligible source of energy. We assume a simple, yet adequate, hydrodynamic profile of the envelope and study the mechanisms which dominate the energy emission and the observed temperature. We consider the diffusion of photons through the envelope while analyzing the ionization fraction and the coupling between radiation and gas. We find that once recombination starts, the observed temperature decreases slowly in time. However, in a typical red supergiant (R...
Geometry of curves and surfaces with Maple
Rovenski, Vladimir
2000-01-01
This concise text on geometry with computer modeling presents some elementary methods for analytical modeling and visualization of curves and surfaces. The author systematically examines such powerful tools as 2-D and 3-D animation of geometric images, transformations, shadows, and colors, and then further studies more complex problems in differential geometry. Well-illustrated with more than 350 figures---reproducible using Maple programs in the book---the work is devoted to three main areas: curves, surfaces, and polyhedra. Pedagogical benefits can be found in the large number of Maple programs, some of which are analogous to C++ programs, including those for splines and fractals. To avoid tedious typing, readers will be able to download many of the programs from the Birkhauser web site. Aimed at a broad audience of students, instructors of mathematics, computer scientists, and engineers who have knowledge of analytical geometry, i.e., method of coordinates, this text will be an excellent classroom resource...
INSTRUMENTATION OF CURVED CANALS: A REVIEW
Directory of Open Access Journals (Sweden)
Senthil Kumar
2013-02-01
Full Text Available INTRODUCTION: Nature seldom draws a straight line. Nowhere is thi s more apparent than in the anatomy of teeth roots and root canal systems o f human teeth. Even teeth with straight roots can harbor severely curved canals. Canal shapi ng is a critical aspect of endodontic treatment because it influences the outcome of the subsequent phases of canal irrigation and filling and the success of the treatment itself. In fact, curved canals are the most common endodontic complexity 1 . The need for some manner of root canal preparation pri or to root canal filling has long been recognized as an essential step in endodontic t reatment. Concepts concerning the role and purpose of this canal preparation, however, have differ ed remarkably at different times in the development of endodontics and in the hands of diffe rent practitioners 2
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.
Classification of Isomonodromy Problems on Elliptic Curves
Levin, A; Zotov, A
2013-01-01
We consider the isomonodromy problems for flat $G$-bundles over punctured elliptic curves $\\Sigma_\\tau$ with regular singularities of connections at marked points. The bundles are classified by their characteristic classes. These classes are elements of the second cohomology group $H^2(\\Sigma_\\tau,{\\mathcal Z}(G))$, where ${\\mathcal Z}(G)$ is the center of $G$. For any complex simple Lie group $G$ and arbitrary class we define the moduli space of flat bundles, and in this way construct the monodromy preserving equations in the Hamiltonian form and their Lax representations. In particular, they include the Painlev\\'e VI equation, its multicomponent generalizations and elliptic Schlesinger equations. The general construction is described for punctured curves of arbitrary genus. We extend the Beilinson-Drinfeld description of the moduli space of Higgs bundles to the case of flat connections. This local description allows us to establish the Symplectic Hecke Correspondence for a wide class of the monodromy preser...
Centrifugally driven relativistic dynamics on curved trajectories
Rogava, A; Osmanov, Z; Rogava, Andria; Dalakishvili, George; Osmanov, Zaza
2003-01-01
Motion of test particles along rotating curved trajectories is considered. The problem is studied both in the laboratory and the rotating frames of reference. It is assumed that the system rotates with the constant angular velocity $\\omega = const$. The solutions are found and analyzed for the case when the form of the trajectory is given by an Archimedes spiral. It is found that particles can reach infinity while they move along these trajectories and the physical interpretation of their behaviour is given. The analogy of this idealized study with the motion of particles along the curved rotating magnetic field lines in the pulsar magnetosphere is pointed out. We discuss further physical development (the conserved total energy case, when $\\omega \
Decay curves in coupled, reverberant spaces
DEFF Research Database (Denmark)
Balin, Jamilla; Nolan, Melanie; Fernandez Grande, Efren;
2016-01-01
; the standard only states that the absorption coefficient of a highly absorbing material will increase and approach a maximum value. This value is usually much higher than 1 when diffusers are added. It is also known that the reproducibility of absorption coefficient measurements in reverberation chambers...... is unsatisfying. This study investigates the effect of panel diffusers, in particular considering that their dispositioning in a room can create coupled spaces, decreasing the effective volume of the chamber, and leading to an overestimation of the absorption coefficient. The decay curves are measured in a small...... in the occupied (with high absorption on the floor) and unoccupied state (without any absorption) are compared. The decay curve in the occupied state without any panels or boundary diffusers has a breakpoint where the slope changes its value. This can also be observed in the unoccupied state with panels placed...
Type II supernovae Early Light Curves
Shussman, Tomer; Nakar, Ehud
2016-01-01
Observations of type II supernova early light, from breakout until recombination, can be used to constrain the explosion energy and progenitor properties. Currently available for this purpose are purely analytic models, which are accurate only to within an order of magnitude, and detailed numerical simulations, which are more accurate but are applied to any event separately. In this paper we derive an analytic model that is calibrated by numerical simulations. This model is much more accurate than previous analytic models, yet it is as simple to use. To derive the model we analyze simulated light curves from numerical explosion of $124$ red supergiant progenitors, calculated using the stellar evolution code MESA. We find that although the structure of the progenitors we consider varies, the resulting light curves can be described rather well based only on the explosion energy, ejecta mass and progenitor radius. Our calibrated analytic model, which is based on these three parameters, reproduces the bolometric ...
PyTransit: Transit light curve modeling
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.
Daylight calculations using constant luminance curves
Energy Technology Data Exchange (ETDEWEB)
Betman, E. [CRICYT, Mendoza (Argentina). Laboratorio de Ambiente Humano y Vivienda
2005-02-01
This paper presents a simple method to manually estimate daylight availability and to make daylight calculations using constant luminance curves calculated with local illuminance and irradiance data and the all-weather model for sky luminance distribution developed in the Atmospheric Science Research Center of the University of New York (ARSC) by Richard Perez et al. Work with constant luminance curves has the advantage that daylight calculations include the problem's directionality and preserve the information of the luminous climate of the place. This permits accurate knowledge of the resource and a strong basis to establish conclusions concerning topics related to the energy efficiency and comfort in buildings. The characteristics of the proposed method are compared with the method that uses the daylight factor. (author)
Degrees of Curves in Abelian Varieties
Debarre, O
1992-01-01
The degree of a curve $C$ in a polarized abelian variety $(X,\\lambda)$ is the integer $d=C\\cdot\\lambda$. When $C$ generates $X$, we find a lower bound on $d$ which depends on $n$ and the degree of the polarization $\\lambda$. The smallest possible degree is $d=n$ and is obtained only for a smooth curve in its Jacobian with its principal polarization (Ran, Collino). The cases $d=n+1$ and $d=n+2$ are studied. Moreover, when $X$ is simple, it is shown, using results of Smyth on the trace of totally positive algebraic integers, that if $d\\le 1.7719\\, n$, then $C$ is smooth and $X$ is isomorphic to its Jacobian. We also get an upper bound on the geometric genus of $C$ in terms of its degree.
Arrangement Computation for Planar Algebraic Curves
Berberich, Eric; Kobel, Alexander; Sagraloff, Michael
2011-01-01
We present a new certified and complete algorithm to compute arrangements of real planar algebraic curves. Our algorithm provides a geometric-topological analysis of the decomposition of the plane induced by a finite number of algebraic curves in terms of a cylindrical algebraic decomposition of the plane. Compared to previous approaches, we improve in two main aspects: Firstly, we significantly reduce the amount of exact operations, that is, our algorithms only uses resultant and gcd as purely symbolic operations. Secondly, we introduce a new hybrid method in the lifting step of our algorithm which combines the usage of a certified numerical complex root solver and information derived from the resultant computation. Additionally, we never consider any coordinate transformation and the output is also given with respect to the initial coordinate system. We implemented our algorithm as a prototypical package of the C++-library CGAL. Our implementation exploits graphics hardware to expedite the resultant and gcd...
Mannheim Curves in Nonflat 3-Dimensional Space Forms
Directory of Open Access Journals (Sweden)
Wenjing Zhao
2015-01-01
Full Text Available We consider the Mannheim curves in nonflat 3-dimensional space forms (Riemannian or Lorentzian and we give the concept of Mannheim curves. In addition, we investigate the properties of nonnull Mannheim curves and their partner curves. We come to the conclusion that a necessary and sufficient condition is that a linear relationship with constant coefficients will exist between the curvature and the torsion of the given original curves. In the case of null curve, we reveal that there are no null Mannheim curves in the 3-dimensional de Sitter space.
The Selmer Groups of Elliptic Curves
Institute of Scientific and Technical Information of China (English)
Fu Zheng WANG
2003-01-01
Let E/K be an elliptic curve with K-rational p-torsion points. The p-Selmer group of Eis described by the image of a map λK and hence an upper bound of its order is given in terms of theclass numbers of the S-ideal class group of K and the p-division field of E.
Operators and higher genus mirror curves
Codesido, Santiago; Gu, Jie; Mariño, Marcos
2017-02-01
We perform further tests of the correspondence between spectral theory and topological strings, focusing on mirror curves of genus greater than one with nontrivial mass parameters. In particular, we analyze the geometry relevant to the SU(3) relativistic Toda lattice, and the resolved C{^3}/Z_6 orbifold. Furthermore, we give evidence that the correspondence holds for arbitrary values of the mass parameters, where the quantization problem leads to resonant states. We also explore the relation between this correspondence and cluster integrable systems.
SS433 Trek 2: light curve analysis.
Fukue, J.; Obana, Y.; Okugami, M.
The authors have calculated theoretical light curves of SS433 during eclipse and precession, using a model in which SS433 consists of a geometrically thick torus around a compact star and a companion star filling the Roche lobe. The favorite combination is that the mass ratio is about 2 (a compact star is a black hole) and the surface temperature of the companion is around 17000K.
Operators and higher genus mirror curves
Codesido, Santiago; Marino, Marcos
2016-01-01
We perform further tests of the correspondence between spectral theory and topological strings, focusing on mirror curves of genus greater than one with nontrivial mass parameters. In particular, we analyze the geometry relevant to the SU(3) relativistic Toda lattice, and the resolved C^3/Z_6 orbifold. Furthermore, we give evidence that the correspondence holds for arbitrary values of the mass parameters, where the quantization problem leads to resonant states. We also explore the relation between this correspondence and cluster integrable systems.
Generalized duality in curved string backgrounds
Giveon, Amit; Roček, Martin
1992-08-01
The elements of O(d, d, Z) are shown to be discrete symmetries of the space of curved string backgrounds that are independent of d coordinates. The explicit action of the symmetries on the backgrounds is described. Particular attention is paid to the dilaton transformation. Such symmetries identify different cosmological solutions and other (possibly) singular backgrounds; for example, it is shown that a compact black string is dual to a charged black hole. The extension to the heterotic string is discussed.
Generalized Duality in Curved String-Backgrounds
Giveon, Amit; Giveon, Amit; Rocek, Martin
1992-01-01
The elements of $O(d,d,\\Z)$ are shown to be discrete symmetries of the space of curved string backgrounds that are independent of $d$ coordinates. The explicit action of the symmetries on the backgrounds is described. Particular attention is paid to the dilaton transformation. Such symmetries identify different cosmological solutions and other (possibly) singular backgrounds; for example, it is shown that a compact black string is dual to a charged black hole. The extension to the heterotic string is discussed.
Growth curve models and statistical diagnostics
Pan, Jian-Xin
2002-01-01
Growth-curve models are generalized multivariate analysis-of-variance models. These models are especially useful for investigating growth problems on short times in economics, biology, medical research, and epidemiology. This book systematically introduces the theory of the GCM with particular emphasis on their multivariate statistical diagnostics, which are based mainly on recent developments made by the authors and their collaborators. The authors provide complete proofs of theorems as well as practical data sets and MATLAB code.
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.
Stable curves and screens on fatgraphs
DEFF Research Database (Denmark)
Penner, Robert; McShane, Greg
The mapping class group invariant ideal cell decomposition of the Teichmueller space of a punctured surface times an open simplex has been used in a number of computations. This paper answers a question about the asymptotics of this decomposition, namely, in a given cell of the decomposition, whi...... curves can be short? Screens are a new combinatorial structure which provide an answer to this question. The heart of the calculation here involves Ptolemy transformations and the triangle inequalities on lambda lengths....
Infrared Light Curves of Type Ia Supernovae
Friedman, Andrew Samuel
2012-05-01
This thesis presents the CfAIR2 data set, which includes over 4000 near-Infrared (NIR) JHK8-band measurements of 104 Type Ia Supernovae (SN Ia) observed from 2005-2011 using PAIRITEL, the 1.3-m Peters Automated InfraRed Imaging TELescope at the Fred Lawrence Whipple Observatory (FLWO) on Mount Hopkins, Arizona. While the discovery of dark energy and most subsequent supernova cosmology has been performed using optical and Ultraviolet wavelength observations of SN Ia, a growing body of evidence suggests that NIR SN Ia observations will be crucial for future cosmological studies. Whereas SN Ia observed at optical wavelengths have been shown to be excellent standardizeable candles, using empirical correlations between luminosity, light curve shape, and color, the CfAIR2 data set strengthens the evidence that SN Ia at NIR wavelengths are essentially standard candles, even without correction for light-curve shape or for reddening. CfAIR2 was obtained as part of the CfA Supernova Program, an ongoing multi-wavelength follow-up effort at FLWO designed to observe high-quality, densely sampled light curves and spectra of hundreds of low-redshift SN Ia. CfAIR2 is the largest homogeneously observed and processed NIR data set of its kind to date, nearly tripling the number of individual JHK8-band observations and nearly doubling the set of SN Ia with published NIR light curves in the literature. Matched only by the recently published Carnegie Supernova Project sample, CfAIR2 complements the large and growing set of low-redshift optical and NIR SN Ia observations obtained by the CfA and other programs, making this data set a unique and particularly valuable local universe anchor for future supernova cosmology.
Refined curve counting on complex surfaces
Göttsche, Lothar; Shende, Vivek
2012-01-01
We define refined invariants which "count" nodal curves in sufficiently ample linear systems on surfaces, conjecture that their generating function is multiplicative, and conjecture explicit formulas in the case of K3 and abelian surfaces. We also give a refinement of the Caporaso-Harris recursion, and conjecture that it produces the same invariants in the sufficiently ample setting. The refined recursion specializes at y = -1 to the Itenberg-Kharlamov-Shustin recursion for Welschinger invari...
Atlas of Secular Light Curves of Comets
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 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).
Navigation in Curved Space-Time
Bahder, T B
2001-01-01
A covariant and invariant theory of navigation in curved space-time with respect to electromagnetic beacons is written in terms of J. L. Synge's two-point invariant world function. Explicit equations are given for navigation in space-time in the vicinity of the Earth in Schwarzschild coordinates and in rotating coordinates. The restricted problem of determining an observer's coordinate time when their spatial position is known is also considered.
Concentration curves, inequality and tax reform
Madden, David
1995-01-01
This paper applies the concept of welfare dominance using concentration curves to household data for Ireland. It identifies marginal tax reforms which would be welfare-enhancing for all social welfare functions satisfying weak restrictions. It also examines cases where stronger restrictions need to be imposed on the social welfare function to yield dominance. These stronger restrictions which we label limited third degree stochastic dominance extends the range of welfare-enhancing marginal ta...
Dynamic equations for curved submerged floating tunnel
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
In virtue of reference Cartesian coordinates, geometrical relations of spatial curved structure are presented in orthogonal curvilinear coordinates. Dynamic equations for helical girder are derived by Hamilton principle. These equations indicate that four generalized displacements are coupled with each other. When spatial structure degenerates into planar curvilinear structure, two generalized displacements in two perpendicular planes are coupled with each other. Dynamic equations for arbitrary curvilinear structure may be obtained by the method used in this paper.