Relevant bibliographies by topics / Time-varying Efficiency

Academic literature on the topic 'Time-varying Efficiency'

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Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "Time-varying Efficiency"

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Marjai, Péter, and Attila Kiss. "Efficiency centrality in time-varying graphs." Acta Universitatis Sapientiae, Informatica 12, no. 1 (July 1, 2020): 5–21. http://dx.doi.org/10.2478/ausi-2020-0001.

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AbstractOne of the most studied aspect of complex graphs is identifying the most influential nodes. There are some local metrics like degree centrality, which is cost-effiective and easy to calculate, although using global metrics like betweenness centrality or closeness centrality can identify influential nodes more accurately, however calculating these values can be costly and each measure has it’s own limitations and disadvantages. There is an ever-growing interest in calculating such metrics in time-varying graphs (TVGs), since modern complex networks can be best modelled with such graphs. In this paper we are investigating the effectiveness of a new centrality measure called efficiency centrality in TVGs. To evaluate the performance of the algorithm Independent Cascade Model is used to simulate infection spreading in four real networks. To simulate the changes in the network we are deleting and adding nodes based on their degree centrality. We are investigating the Time-Constrained Coverage and the magnitude of propagation resulted by the use of the algorithm.
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Attanasio, Orazio P. "Risk, Time-Varying Second Moments and Market Efficiency." Review of Economic Studies 58, no. 3 (May 1991): 479. http://dx.doi.org/10.2307/2298007.

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Ge, Tingting. "Time-varying transmission efficiency of China’s monetary policy." China Economic Journal 12, no. 1 (December 17, 2018): 32–51. http://dx.doi.org/10.1080/17538963.2018.1556421.

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Charfeddine, Lanouar, and Karim Ben Khediri. "Time varying market efficiency of the GCC stock markets." Physica A: Statistical Mechanics and its Applications 444 (February 2016): 487–504. http://dx.doi.org/10.1016/j.physa.2015.09.063.

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Fazlollahi, Negar, Nesrin Ozatac, and Korhan K. Gokmenoglu. "Evolving time-varying market efficiency of energy stock market." Environmental Science and Pollution Research 27, no. 36 (August 15, 2020): 45539–54. http://dx.doi.org/10.1007/s11356-020-09887-7.

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Parshakov, Petr. "Observing unobservable: estimating the time-varying efficiency of intellectual capital." Measuring Business Excellence 21, no. 4 (November 20, 2017): 377–87. http://dx.doi.org/10.1108/mbe-05-2017-0024.

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Purpose Company intellectual capital (IC) is nowadays considered as a key resource that can transform a company’s value. For this reason, the efficiency of IC is crucial for all stakeholders. Evaluating efficiency is difficult, because IC is partly unobservable and its efficiency varies across time. The aim of this study is to suggest a methodology for estimating the dynamic efficiency of a company’s intellectual resources. Design/methodology/approach The panel data model suggested by Kneip et al. (2012) is used to estimate dynamic efficiency. The main feature of this model is that the unobservable component has a multi-dimensional factor structure. Taking advantage of the ability of this model to control for unobserved complex heterogeneity, the authors use the results in further stochastic frontier analysis. A data set containing information about Russian companies for the period from 2001 to 2010 is used. Findings In this paper, the dynamic efficiency of Russian companies is estimated. It is shown that, using the traditional efficiency estimate, companies can be overestimated. Research limitations/implications The main limitation of the suggested methodology is that it is necessary to have a long panel data structure. Practical implications Taking advantage of time-varying efficiency, one can estimate the efficiency growth rate as a measure of performance, standard deviation as a measure of risk and autocorrelation as a measure of stability. Originality/value This is the first study to present clear evidence of the time-varying nature of IC efficiency. On the methodological side, the paper presents a fairly simple method capable of estimating various indicators of a company’s efficiency.
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Henningsson, Per, and Richard J. Bomphrey. "Time-varying span efficiency through the wingbeat of desert locusts." Journal of The Royal Society Interface 9, no. 71 (November 23, 2011): 1177–86. http://dx.doi.org/10.1098/rsif.2011.0749.

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The flight performance of animals depends greatly on the efficacy with which they generate aerodynamic forces. Accordingly, maximum range, load-lifting capacity and peak accelerations during manoeuvres are all constrained by the efficiency of momentum transfer to the wake. Here, we use high-speed particle image velocimetry (1 kHz) to record flow velocities in the near wake of desert locusts ( Schistocerca gregaria , Forskål). We use the measured flow fields to calculate time-varying span efficiency throughout the wing stroke cycle. The locusts are found to operate at a maximum span efficiency of 79 per cent, typically at a plateau of about 60 per cent for the majority of the downstroke, but at lower values during the upstroke. Moreover, the calculated span efficiencies are highest when the largest lift forces are being generated (90% of the total lift is generated during the plateau of span efficiency) suggesting that the combination of wing kinematics and morphology in locust flight perform most efficiently when doing the most work.
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Desli, Evangelia, Subhash C. Ray, and Subal C. Kumbhakar. "A dynamic stochastic frontier production model with time-varying efficiency." Applied Economics Letters 10, no. 10 (August 2003): 623–26. http://dx.doi.org/10.1080/1350485032000133291.

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Shi, Peng, and Wei Zhang. "Time-varying X-efficiency: evidence from US property casualty insurers." Applied Economics Letters 18, no. 3 (February 2011): 217–21. http://dx.doi.org/10.1080/13504850903559559.

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Ding, Mengying, and Yali Dong. "Robust Finite-time Boundedness of Discrete-time Neural Networks with Time-varying Delays." WSEAS TRANSACTIONS ON INFORMATION SCIENCE AND APPLICATIONS 17 (February 23, 2021): 146–55. http://dx.doi.org/10.37394/23209.2020.17.18.

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This paper is concerned with the problem of robust finite-time boundedness for the discrete-time neural networks with time-varying delays. By constructing an appropriate Lyapunov-Krasovskii functional, we propose the sufficient conditions which ensure the robust finite-time boundedness of the discrete-time neural networks with time-varying delay in terms of linear matrix inequalities. Then the sufficient conditions of robust finite-time stability for the discrete-time neural networks with time-varying delays are given. Finally, a numerical example is presented to illustrate the efficiency of proposed methods.
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Dissertations / Theses on the topic "Time-varying Efficiency"

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Festger, Adam Douglas. "Analysis of hydraulic capture zones and efficiency under time-varying flow and pumping conditions." Thesis, The University of Arizona, 2000. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_2000_30_sip1_w.pdf&type=application/pdf.

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Liu, Yuna. "Essays on Stock Market Integration - On Stock Market Efficiency, Price Jumps and Stock Market Correlations." Doctoral thesis, Umeå universitet, Nationalekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-119873.

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This thesis consists of four self-contained papers related to the change of market structure and the quality of equity market. In Paper [I] we found, by using of a Flexible Dynamic Component Correlations (FDCC) model, that the creation of a common cross-border stock trading platform has increased the long-run trends in conditional correlations between foreign and domestic stock market returns. In Paper [II] we study whether the creation of a uniform Nordic and Baltic stock trading platform has affected weak-form information efficiency. The results indicate that the stock market consolidations have had a positive effect on the information efficiency and turnover for an average firm. The merger effects are, however, asymmetrically distributed in the sense that relatively large (small) firms located on relatively large (small) markets experience an improved (reduced) information efficiency and turnover. Although the results indicate that changes in the level of investor attention (measured by turnover) may explain part of the changes in information efficiency, they also lend support to the hypothesis that merger effects may partially be driven by changes in the composition of informed versus uninformed investors following a stock. Paper [III] analyzes whether the measured level of trust in different countries can explain bilateral stock market correlations. One finding is that generalized trust among nations is a robust predictor for stock market correlations. Another is that the trust effect is larger for countries which are close to each other. This indicates that distance mitigates the trust effect. Finally, we confirm the effect of trust upon stock market correlations, by using particular trust data (bilateral trust between country A and country B) as an alternative measurement of trust. In Paper [IV] we present the impact of the stock market mergers that took place in the Nordic countries during 2000 – 2007 on the probabilities for stock price jumps, i.e. for relatively extreme price movements. The main finding is that stock market mergers, on average, reduce the likelihood of observing stock price jumps. The effects are asymmetric in the sense that the probability of sudden price jumps is reduced for large and medium size firms whereas the effect is ambiguous for small size firms. The results also indicate that the market risk has been reduced after the stock market consolidations took place.
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Burchett, Woodrow. "Improving the Computational Efficiency in Bayesian Fitting of Cormack-Jolly-Seber Models with Individual, Continuous, Time-Varying Covariates." UKnowledge, 2017. http://uknowledge.uky.edu/statistics_etds/27.

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The extension of the CJS model to include individual, continuous, time-varying covariates relies on the estimation of covariate values on occasions on which individuals were not captured. Fitting this model in a Bayesian framework typically involves the implementation of a Markov chain Monte Carlo (MCMC) algorithm, such as a Gibbs sampler, to sample from the posterior distribution. For large data sets with many missing covariate values that must be estimated, this creates a computational issue, as each iteration of the MCMC algorithm requires sampling from the full conditional distributions of each missing covariate value. This dissertation examines two solutions to address this problem. First, I explore variational Bayesian algorithms, which derive inference from an approximation to the posterior distribution that can be fit quickly in many complex problems. Second, I consider an alternative approximation to the posterior distribution derived by truncating the individual capture histories in order to reduce the number of missing covariates that must be updated during the MCMC sampling algorithm. In both cases, the increased computational efficiency comes at the cost of producing approximate inferences. The variational Bayesian algorithms generally do not estimate the posterior variance very accurately and do not directly address the issues with estimating many missing covariate values. Meanwhile, the truncated CJS model provides a more significant improvement in computational efficiency while inflating the posterior variance as a result of discarding some of the data. Both approaches are evaluated via simulation studies and a large mark-recapture data set consisting of cliff swallow weights and capture histories.
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Perelman, Erez. "Characterizing time varying program behavior for efficient simulation." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3259366.

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Thesis (Ph. D.)--University of California, San Diego, 2007.
Title from first page of PDF file (viewed June 22, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 167-173).
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Johansson, Jimmy. "Efficient Information Visualization of Multivariate and Time-Varying Data." Doctoral thesis, Linköping : Department of Science and Technology, Linköping University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11643.

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Vengattaramane, Kameswaran. "Efficient Reconstruction of Two-Periodic Nonuniformly Sampled Signals Applicable to Time-Interleaved ADCs." Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6253.

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Nonuniform sampling occurs in many practical applications either intentionally or unintentionally. This thesis deals with the reconstruction of two-periodic nonuniform signals which is of great importance in two-channel time-interleaved analog-to-digital converters. In a two-channel time-interleaved ADC, aperture delay mismatch between the channels gives rise to a two-periodic nonuniform sampling pattern, resulting in distortion and severely affecting the linearity of the converter. The problem is solved by digitally recovering a uniformly sampled sequence from a two-periodic nonuniformly sampled set. For this purpose, a time-varying FIR filter is employed. If the sampling pattern is known and fixed, this filter can be designed in an optimal way using least-squares or minimax design. When the sampling pattern changes now and then as during the normal operation of time-interleaved ADC, these filters have to be redesigned. This has implications on the implementation cost as general on-line design is cumbersome. To overcome this problem, a novel time-varying FIR filter with polynomial impulse response is developed and characterized in this thesis. The main advantage with these filters is that on-line design is no longer needed. It now suffices to perform only one design before implementation and in the implementation it is enough to adjust only one variable parameter when the sampling pattern changes. Thus the high implementation cost is decreased substantially.

Filter design and the associated performance metrics have been validated using MATLAB. The design space has been explored to limits imposed by machine precision on matrix inversions. Studies related to finite wordlength effects in practical filter realisations have also been carried out. These formulations can also be extended to the general M - periodic nonuniform sampling case.

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Tuffner, Francis K. "Computationally efficient weighted updating of statistical parameter estimates for time varying signals with application to power system identification." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1674094221&sid=4&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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Alrabadi, Dima W. H. "Systematic Liquidity Risk and Stock Price Reaction to Large One-Day Price Changes: Evidence from London Stock Exchange." Thesis, University of Bradford, 2009. http://hdl.handle.net/10454/4323.

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This thesis investigates systematic liquidity risk and short-term stock price reaction to large one-day price changes. We study 642 constituents of the FTSALL share index over the period from 1st July 1992 to 29th June 2007. We show that the US evidence of a priced systematic liquidity risk of Pastor and Stambaugh (2003) and Liu (2006) is not country-specific. Particularly, systematic liquidity risk is priced in the London Stock Exchange when Amihud's (2002) illiquidity ratio is used as a liquidity proxy. Given the importance of systematic liquidity risk in the asset pricing literature, we are interested in testing whether the different levels of systematic liquidity risk across stocks can explain the anomaly following large one-day price changes. Specifically, we expect that the stocks with high sensitivity to the fluctuations in aggregate market liquidity to be more affected by price shocks. We find that most liquid stocks react efficiently to price shocks, while the reactions of the least liquid stocks support the uncertain information hypothesis. However, we show that time-varying risk is more important than systematic liquidity risk in explaining the price reaction of stocks in different liquidity portfolios. Indeed, the time varying risk explains nearly all of the documented overreaction and underreaction following large one-day price changes. Our evidence suggests that the observed anomalies following large one-day price shocks are caused by the pricing errors arising from the use of static asset pricing models. In particular, the conditional asset pricing model of Harris et al. (2007), which allow both risk and return to vary systematically over time, explain most of the observed anomalies. This evidence supports the Brown et al. (1988) findings that both risk and return increase in a systematic fashion following price shocks.
Yarmouk University, Jordan.
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Alrabadi, Dima Waleed Hanna. "Systematic liquidity risk and stock price reaction to large one-day price changes : evidence from London Stock Exchange." Thesis, University of Bradford, 2009. http://hdl.handle.net/10454/4323.

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This thesis investigates systematic liquidity risk and short-term stock price reaction to large one-day price changes. We study 642 constituents of the FTSALL share index over the period from 1st July 1992 to 29th June 2007. We show that the US evidence of a priced systematic liquidity risk of Pastor and Stambaugh (2003) and Liu (2006) is not country-specific. Particularly, systematic liquidity risk is priced in the London Stock Exchange when Amihud's (2002) illiquidity ratio is used as a liquidity proxy. Given the importance of systematic liquidity risk in the asset pricing literature, we are interested in testing whether the different levels of systematic liquidity risk across stocks can explain the anomaly following large one-day price changes. Specifically, we expect that the stocks with high sensitivity to the fluctuations in aggregate market liquidity to be more affected by price shocks. We find that most liquid stocks react efficiently to price shocks, while the reactions of the least liquid stocks support the uncertain information hypothesis. However, we show that time-varying risk is more important than systematic liquidity risk in explaining the price reaction of stocks in different liquidity portfolios. Indeed, the time varying risk explains nearly all of the documented overreaction and underreaction following large one-day price changes. Our evidence suggests that the observed anomalies following large one-day price shocks are caused by the pricing errors arising from the use of static asset pricing models. In particular, the conditional asset pricing model of Harris et al. (2007), which allow both risk and return to vary systematically over time, explain most of the observed anomalies. This evidence supports the Brown et al. (1988) findings that both risk and return increase in a systematic fashion following price shocks.
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Sando, Simon Andrew. "Estimation of a class of nonlinear time series models." Thesis, Queensland University of Technology, 2004. https://eprints.qut.edu.au/15985/1/Simon_Sando_Thesis.pdf.

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The estimation and analysis of signals that have polynomial phase and constant or time-varying amplitudes with the addititve noise is considered in this dissertation.Much work has been undertaken on this problem over the last decade or so, and there are a number of estimation schemes available. The fundamental problem when trying to estimate the parameters of these type of signals is the nonlinear characterstics of the signal, which lead to computationally difficulties when applying standard techniques such as maximum likelihood and least squares. When considering only the phase data, we also encounter the well known problem of the unobservability of the true noise phase curve. The methods that are currently most popular involve differencing in phase followed by regression, or nonlinear transformations. Although these methods perform quite well at high signal to noise ratios, their performance worsens at low signal to noise, and there may be significant bias. One of the biggest problems to efficient estimation of these models is that the majority of methods rely on sequential estimation of the phase coefficients, in that the highest-order parameter is estimated first, its contribution removed via demodulation, and the same procedure applied to estimation of the next parameter and so on. This is clearly an issue in that errors in estimation of high order parameters affect the ability to estimate the lower order parameters correctly. As a result, stastical analysis of the parameters is also difficult. In thie dissertation, we aim to circumvent the issues of bias and sequential estiamtion by considering the issue of full parameter iterative refinement techniques. ie. given a possibly biased initial estimate of the phase coefficients, we aim to create computationally efficient iterative refinement techniques to produce stastically efficient estimators at low signal to noise ratios. Updating will be done in a multivariable manner to remove inaccuracies and biases due to sequential procedures. Stastical analysis and extensive simulations attest to the performance of the schemes that are presented, which include likelihood, least squares and bayesian estimation schemes. Other results of importance to the full estimatin problem, namely when there is error in the time variable, the amplitude is not constant, and when the model order is not known, are also condsidered.
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Books on the topic "Time-varying Efficiency"

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Shaik, Saleem. Accounting for (in)efficiency in the estimation of time-varying returns to scale. Fargo, N.D: Dept. of Agribusiness and Applied Economics, 2008.

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Shattock, Andrew J., Cliff C. Kerr, Robyn M. Stuart, Emiko Masaki, Nicole Fraser, Clemens Benedikt, Marelize Gorgens, David P. Wilson, and Richard T. Gray. In the Interests of Time: Improving HIV Allocative Efficiency Modelling via Optimal Time-Varying Allocations. Wiley, 2016. http://dx.doi.org/10.1596/31379.

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Efficient encoding and rendering of time-varying volume data. Hampton, VA: Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, 1998.

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Kwan-Liu, Ma, and Institute for Computer Applications in Science and Engineering., eds. Efficient encoding and rendering of time-varying volume data. Hampton, VA: Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, 1998.

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Book chapters on the topic "Time-varying Efficiency"

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Zheng, Yadi, Anan Zhang, Chengqian Zhang, and Luyang Gou. "Energy Efficiency Model of the PIES Taking into Account the Time-Varying Characteristics of Equipment Operating Conditions." In Lecture Notes in Electrical Engineering, 563–70. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-3927-3_56.

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Mustafa, Ali, Salman Ahmed, Najam ul Islam, and Ahsan Tufail. "An Efficient Agent Scheming in Distributed Time Varying Networks." In Proceedings of SAI Intelligent Systems Conference (IntelliSys) 2016, 308–20. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-56991-8_23.

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Jithendranathan, Thadavillil. "An Empirical Study of Time-Varying Return Correlations and the Efficient Set of Portfolios." In Advances in Risk Management, 265–77. London: Palgrave Macmillan UK, 2007. http://dx.doi.org/10.1057/9780230625846_14.

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Borms, Samuel, Kris Boudt, Frederiek Van Holle, and Joeri Willems. "Semi-supervised Text Mining for Monitoring the News About the ESG Performance of Companies." In Data Science for Economics and Finance, 217–39. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-66891-4_10.

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AbstractWe present a general monitoring methodology to summarize news about predefined entities and topics into tractable time-varying indices. The approach embeds text mining techniques to transform news data into numerical data, which entails the querying and selection of relevant news articles and the construction of frequency- and sentiment-based indicators. Word embeddings are used to achieve maximally informative news selection and scoring. We apply the methodology from the viewpoint of a sustainable asset manager wanting to actively follow news covering environmental, social, and governance (ESG) aspects. In an empirical analysis, using a Dutch-written news corpus, we create news-based ESG signals for a large list of companies and compare these to scores from an external data provider. We find preliminary evidence of abnormal news dynamics leading up to downward score adjustments and of efficient portfolio screening.
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Hüwel, Jan David, Florian Haselbeck, Dominik G. Grimm, and Christian Beecks. "Dynamically Self-adjusting Gaussian Processes for Data Stream Modelling." In Lecture Notes in Computer Science, 96–114. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-15791-2_10.

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AbstractOne of the major challenges in time series analysis are changing data distributions, especially when processing data streams. To ensure an up-to-date model delivering useful predictions at all times, model reconfigurations are required to adapt to such evolving streams. For Gaussian processes, this might require the adaptation of the internal kernel expression. In this paper, we present dynamically self-adjusting Gaussian processes by introducing Event-Triggered Kernel Adjustments in Gaussian process modelling (ETKA), a novel data stream modelling algorithm that can handle evolving and changing data distributions. To this end, we enhance the recently introduced Adjusting Kernel Search with a novel online change point detection method. Our experiments on simulated data with varying change point patterns suggest a broad applicability of ETKA. On real-world data, ETKA outperforms comparison partners that differ regarding the model adjustment and its refitting trigger in nine respective ten out of 14 cases. These results confirm ETKA’s ability to enable a more accurate and, in some settings, also more efficient data stream processing via Gaussian processes.
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Rawat, Shweta, and Sanjay Kumar. "The Feasibility Study of Green Microalgae Assisted Coal Mine Effluent Desalination." In Proceedings of the Conference BioSangam 2022: Emerging Trends in Biotechnology (BIOSANGAM 2022), 255–67. Dordrecht: Atlantis Press International BV, 2022. http://dx.doi.org/10.2991/978-94-6463-020-6_25.

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AbstractCarbon-neutral sustainable approaches are highly demanding in the coal energy sector. Coal mine effluent disposal is a severe challenge with crucial concern issues of salinity hazard and heavy metal contamination due to long-duration water and coal interaction. The medium to the high salinity of coal mine effluent leads towards irrigation unsuitability due to the negative impact upon infiltration and permeability of nutrients from the soil to plant. Focusing on the international irrigation water quality standards given by the Food and Agriculture Organization (FAO) of the United Nations, most coal mine effluents are considered negatively impacting crops, soil fertility, groundwater, and aquatic life. Therefore, the current study investigates the direct cultivation suitability of Chlorella pyrenoidosa to simultaneously treat coal mine effluent for salinity removal and biomass production. Initially, C. pyrenoidosa culture adaptation in varying concentrations of coal mine effluents (25%–100%) in coal mine effluent, which are collected from two different points of coal mine named as coal mine effluent 1 (CME1) and coal mine effluent 2 (CME2). Evaluating C. pyrenoidosa growth kinetics, it was observed that the doubling time extended from 2.25 days (100% BG-11 as a medium; control) to 4.33 days (100% CME as a medium). Interestingly, the highest value for biomass production was 1.78 ± 0.12 g/ L with 25% CME 1 supplemented with essential growth nutrients; this value lies near 100% BG11 supplemented growth, 1.81 ± 0.05 g/L. In the current study, taking salinity removal as a prime concern, 100% utilization of CME-2 in place of BG-11 medium was very significant for salinity reduction from 4.80 ± 0.50 mS/cm (initial) to 0.98 ± 0.02 mS/cm (final) during 14 days batch growth. In continuation of that, the significant finding was salinity reduction of both samples (50% and 75% sample) to the level of 0.7 mS/ cm, which lies under the FAO guidelines for irrigation. Present findings also revealed an alternative to conventional processes, i.e., thermal and membrane desalination. Microalgae-assisted desalination is a novel, energy-efficient, eco-sustainable, cost-effective, and long-term operational approach. It has good potential to treat medium to sub-optimal salinity of coal mine effluent coupled with high-value biomass production.
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Kamışlı, Melik, Serap Kamışlı, and Fatih Temizel. "Globalization and Time-Varying Market Efficiency." In Advances in Business Strategy and Competitive Advantage, 480–99. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7180-3.ch027.

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The main purpose of this study is to determine time-varying weak form efficiency of 18 Borsa İstanbul sub-sector indices. In line with this purpose weak form efficiency is tested with innovative technique alongside traditional methods. The study indicated that bank, real estate invest trusts, holding & investments, telecommunication, wood, paper & printing, insurance, tourism and transportation indices are not linear. The weak form efficiency of aforementioned indices is analyzed with a rolling KSS unit root test developed by Yılancı. It is concluded depending on the applied tests that weak form efficiency of all of the nonlinear sub-sector indices has a time-varying structure. Results also showed that global scale events affect weak form efficiency of the indices in different durations. Findings gained from the study can be used by investors in strategic portfolio management decisions and by policy makers as well.
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Kamikura, Kazuto, Hirohisa Jozawa, Hiroshi Watanabe, Hiroshi Kotera, and Kazunori Shimamura. "A High Efficiency Coding Method." In Time-Varying Image Processing and Moving Object Recognition, 4, 127–32. Elsevier, 1997. http://dx.doi.org/10.1016/b978-044482307-6/50018-7.

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Pires, Carlos, Enrico Polese, and Mario Guglielmo. "Tradeoffs on Motion Compensation/DCT Hybrid Coding: an efficiency analysis." In Time-Varying Image Processing and Moving Object Recognition, 163–66. Elsevier, 1994. http://dx.doi.org/10.1016/b978-0-444-81467-8.50024-7.

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"Time-Varying Risk Premia and the Efficiency of the New Zealand Foreign Exchange Market." In Foreign Exchange Issues, Capital Markets and International Banking in the 1990s (RLE Banking & Finance), 81–92. Routledge, 2012. http://dx.doi.org/10.4324/9780203108819-12.

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Conference papers on the topic "Time-varying Efficiency"

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Rickard, Scott, Konstantinos Drakakis, and Nikolaos Tsakalozos. "On the efficiency of time-varying channel models." In 2006 40th Annual Conference on Information Sciences and Systems. IEEE, 2006. http://dx.doi.org/10.1109/ciss.2006.286677.

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Yunping Sun and Zhen Li. "Adaptive repetitive control for nonlinear systems with time-varying parameters uncertainty." In Symposium on ICT and Energy Efficiency and Workshop on Information Theory and Security (CIICT 2012). Institution of Engineering and Technology, 2012. http://dx.doi.org/10.1049/cp.2012.1897.

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Chioncel, Cristian Paul, Cristian Murarescu, Elisabeta Spunei, and Marius Dudu. "Energy efficiency at wind power systems operating at time varying wind speed." In 2019 International Conference of Computer Science and Renewable Energies (ICCSRE). IEEE, 2019. http://dx.doi.org/10.1109/iccsre.2019.8807676.

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Paixao, Douglas Kataki, and Andrea Chiuchiarelli. "Adaptive control for efficiency improvement in time-varying Visible Light Communication systems." In 2021 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC). IEEE, 2021. http://dx.doi.org/10.1109/imoc53012.2021.9624898.

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Wang, Rui, Olivier Renaudin, Ricardo M. Bernas, and Andreas F. Molisch. "Efficiency Improvement for Path Detection and Tracking Algorithm in a Time-Varying Channel." In 2015 IEEE 82nd Vehicular Technology Conference (VTC Fall). IEEE, 2015. http://dx.doi.org/10.1109/vtcfall.2015.7390911.

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Lin, Xiao-Hui, Yu-Kwong Kwok, and Hui Wang. "On Improving the Energy Efficiency of Wireless Sensor Networks under Time-Varying Environment." In 32nd IEEE Conference on Local Computer Networks (LCN 2007). IEEE, 2007. http://dx.doi.org/10.1109/lcn.2007.87.

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Hanachi, Houman, Jie Liu, Avisekh Banerjee, and Ying Chen. "Prediction of Compressor Fouling Rate Under Time Varying Operating Conditions." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-56242.

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Performance of the compressors deteriorates due to detrimental effects of fouling on the aerodynamic flow characteristic. The compressors need periodic clean up services to re-gain the designed performance. Apart from the operating time, the ambient and the operating conditions affect the fouling phenomenon making accurate scheduling for predictive maintenance very difficult. In this work, the symptoms of compressor fouling are captured through the evolution of the compressor map in terms of loss of isentropic efficiency and mass flow decrease. Compressor mass flow and the rate of humidity condensation at the inlet of the compressor are identified as the effective factors on the fouling rate. Humidity condensation has a competing effect on fouling rate; increment of the condensed humidity up to a certain level accelerates the fouling rate, while additional mist has an inverse effect. The complex effect of the condensed humidity along with the air mass flow is extracted through training an adaptive neuro-fuzzy inference system. The resulting model reveals how the efficiency and the mass flow of the compressor map vary as a result of fouling development, given the mass flow and the humidity condensation history. The methodology is verified using data from a similar compressor commissioned at a different period.
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Yuan, Chenggang, Andrew Plummer, and Min Pan. "Efficient Control of a Switched Inertance Hydraulic Converter With a Time-Varying Load." In ASME/BATH 2021 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/fpmc2021-68832.

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Abstract Switched inertance hydraulic converters (SIHC) are new digital hydraulic devices which provide an alternative to conventional proportional or servo valve-controlled systems in hydraulic fluid power. SIHCs can adjust and control flow and pressure by means of using digital control signals that do not rely on throttling the flow and dissipation of power, and provide hydraulic systems with high-energy efficiency, good controllability, and insensitivity to contamination. A flow booster is one configuration of SIHCs which can deliver more flow than the supply flow. In this article, the loading effects of SIHCs are investigated by applying a time-varying load on the flow booster. A control system consisting of a PI controller and a switching frequency optimizer was designed to operate a flow booster at its optimal switching frequencies and switching ratios to maximize system efficiency when the load varies. Simulated results showed that the flow booster with the proposed controller has very good dynamic response and can be operated at an average efficiency of 70% with a time-varying load. Compared with only using a PI controller, the proposed controller can improve the overall efficiency by up to 20%. As time-varying loading conditions are commonly found in hydraulic applications, this work constitutes an important contribution to the design and development of high-efficiency SIHCs.
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Söffker, Dirk, and Peter C. Müller. "Control of Dynamic Systems With Nonlinearities and Time Varying Parameters." In ASME 1993 Design Technical Conferences. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/detc1993-0114.

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Abstract The well-known theory of disturbance rejection control and the experience of using a generalized technique with universal fault model for building observers and regulators for the estimation and compensation of disturbances and unmodeled or uncertain effects as well, could be used for controlling dynamic systems with time varying parameters and nonlinearities. Based on a linear time-invariant model the effects of non-linearities and unmodeled dynamics are estimated by an extended observer scheme. Using this information these dynamic effects will be compensated by the developed compensation scheme. Here also different compensation techniques of disturbance rejection control are discussed, compared, and modified. The simulation example of an inverted flexible pendulum shows the efficiency of the method controlling an unstable mechanical system without exact knowledge of structure and parameters of nonlinearity and time-variance.
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Svec, Petr, Atul Thakur, Brual C. Shah, and Satyandra K. Gupta. "USV Trajectory Planning for Time Varying Motion Goals in an Environment With Obstacles." In ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-71239.

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Safe and efficient following of a time varying motion goal by an autonomous unmanned surface vehicle (USV) in a sea environment with obstacles is a challenge. The vehicle’s tracking capability is inherently influenced by its dynamics, the motion characteristics of the motion goal, as well as by the configuration of obstacles in the marine environment. We have developed an approach that utilizes a lattice-based trajectory planning to generate a dynamically feasible, resolution optimal, collision-free trajectory to allow the vehicle to reliably reach the motion goal. We utilized a trajectory following controller to achieve high tracking efficiency while still preserving motion safety. The entire approach is based on the developed USV system architecture that encapsulates the necessary trajectory planning components. We demonstrated the effectiveness of the developed planner in a simulated environment with static obstacles. In addition, we have developed a physical evaluation setup.
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Reports on the topic "Time-varying Efficiency"

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Mims, Natalie A., Tom Eckman, and Charles Goldman. Time-varying value of electric energy efficiency. Office of Scientific and Technical Information (OSTI), June 2017. http://dx.doi.org/10.2172/1398500.

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Mims, Natalie, Tom Eckman, and Lisa C. Schwartz. Time-Varying Value of Energy Efficiency in Michigan. Office of Scientific and Technical Information (OSTI), April 2018. http://dx.doi.org/10.2172/1432251.

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Kularatne, Dhanushka N., Subhrajit Bhattacharya, and M. Ani Hsieh. Computing Energy Optimal Paths in Time-Varying Flows. Drexel University, 2016. http://dx.doi.org/10.17918/d8b66v.

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Autonomous marine vehicles (AMVs) are typically deployed for long periods of time in the ocean to monitor different physical, chemical, and biological processes. Given their limited energy budgets, it makes sense to consider motion plans that leverage the dynamics of the surrounding flow field so as to minimize energy usage for these vehicles. In this paper, we present two graph search based methods to compute energy optimal paths for AMVs in two-dimensional (2-D) time-varying flows. The novelty of the proposed algorithms lies in a unique discrete graph representation of the 3-D configuration space spanned by the spatio-temporal coordinates. This enables a more efficient traversal through the search space, as opposed to a full search of the spatio-temporal configuration space. Furthermore, the proposed strategy results in solutions that are closer to the global optimal when compared to greedy searches through the spatial coordinates alone. We demonstrate the proposed algorithms by computing optimal energy paths around the Channel Islands in the Santa Barbara bay using time-varying flow field forecasts generated by the Regional Ocean Model System. We verify the accuracy of the computed paths by comparing them with paths computed via an optimal control formulation.
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Miles, Gaines E., Yael Edan, F. Tom Turpin, Avshalom Grinstein, Thomas N. Jordan, Amots Hetzroni, Stephen C. Weller, Marvin M. Schreiber, and Okan K. Ersoy. Expert Sensor for Site Specification Application of Agricultural Chemicals. United States Department of Agriculture, August 1995. http://dx.doi.org/10.32747/1995.7570567.bard.

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In this work multispectral reflectance images are used in conjunction with a neural network classifier for the purpose of detecting and classifying weeds under real field conditions. Multispectral reflectance images which contained different combinations of weeds and crops were taken under actual field conditions. This multispectral reflectance information was used to develop algorithms that could segment the plants from the background as well as classify them into weeds or crops. In order to segment the plants from the background the multispectrial reflectance of plants and background were studied and a relationship was derived. It was found that using a ratio of two wavelenght reflectance images (750nm and 670nm) it was possible to segment the plants from the background. Once ths was accomplished it was then possible to classify the segmented images into weed or crop by use of the neural network. The neural network developed for this work is a modification of the standard learning vector quantization algorithm. This neural network was modified by replacing the time-varying adaptation gain with a constant adaptation gain and a binary reinforcement function. This improved accuracy and training time as well as introducing several new properties such as hill climbing and momentum addition. The network was trained and tested with different wavelength combinations in order to find the best results. Finally, the results of the classifier were evaluated using a pixel based method and a block based method. In the pixel based method every single pixel is evaluated to test whether it was classified correctly or not and the best weed classification results were 81% and its associated crop classification accuracy is 57%. In the block based classification method, the image was divided into blocks and each block was evaluated to determine whether they contained weeds or not. Different block sizes and thesholds were tested. The best results for this method were 97% for a block size of 8 inches and a pixel threshold of 60. A simulation model was developed to 1) quantify the effectiveness of a site-specific sprayer, 2) evaluate influence of diffeent design parameters on efficiency of the site-specific sprayer. In each iteration of this model, infected areas (weed patches) in the field were randomly generated and the amount of required herbicides for spraying these areas were calculated. The effectiveness of the sprayer was estimated for different stain sizes, nozzle types (conic and flat), nozzle sizes and stain detection levels of the identification system. Simulation results indicated that the flat nozzle is much more effective as compared to the conic nozzle and its relative efficiency is greater for small nozzle sizes. By using a site-specific sprayer, the average ratio between the spraying areas and the stain areas is about 1.1 to 1.8 which can save up to 92% of herbicides, especially when the proportion of the stain areas is small.
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Baral, Aniruddha, Jeffery Roesler, and Junryu Fu. Early-age Properties of High-volume Fly Ash Concrete Mixes for Pavement: Volume 2. Illinois Center for Transportation, September 2021. http://dx.doi.org/10.36501/0197-9191/21-031.

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High-volume fly ash concrete (HVFAC) is more cost-efficient, sustainable, and durable than conventional concrete. This report presents a state-of-the-art review of HVFAC properties and different fly ash characterization methods. The main challenges identified for HVFAC for pavements are its early-age properties such as air entrainment, setting time, and strength gain, which are the focus of this research. Five fly ash sources in Illinois have been repeatedly characterized through x-ray diffraction, x-ray fluorescence, and laser diffraction over time. The fly ash oxide compositions from the same source but different quarterly samples were overall consistent with most variations observed in SO3 and MgO content. The minerals present in various fly ash sources were similar over multiple quarters, with the mineral content varying. The types of carbon present in the fly ash were also characterized through x-ray photoelectron spectroscopy, loss on ignition, and foam index tests. A new computer vision–based digital foam index test was developed to automatically capture and quantify a video of the foam layer for better operator and laboratory reliability. The heat of hydration and setting times of HVFAC mixes for different cement and fly ash sources as well as chemical admixtures were investigated using an isothermal calorimeter. Class C HVFAC mixes had a higher sulfate imbalance than Class F mixes. The addition of chemical admixtures (both PCE- and lignosulfonate-based) delayed the hydration, with the delay higher for the PCE-based admixture. Both micro- and nano-limestone replacement were successful in accelerating the setting times, with nano-limestone being more effective than micro-limestone. A field test section constructed of HVFAC showed the feasibility and importance of using the noncontact ultrasound device to measure the final setting time as well as determine the saw-cutting time. Moreover, field implementation of the maturity method based on wireless thermal sensors demonstrated its viability for early opening strength, and only a few sensors with pavement depth are needed to estimate the field maturity.
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Global Education Monitoring Report - Non-state actors in education: Who chooses? Who loses? UNESCO, December 2021. http://dx.doi.org/10.54676/ytjt5864.

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Non-state actors’ role extends beyond provision of schooling to interventions at various education levels and influence spheres. Alongside its review of progress towards SDG 4, including emerging evidence on the COVID-19 pandemic’s impact, the 2021/2 Global Education Monitoring Report urges governments to see all institutions, students and teachers as part of a single system. Standards, information, incentives and accountability should help governments protect, respect and fulfil the right to education of all, without turning their eyes away from privilege or exploitation. Publicly funded education does not have to be publicly provided but disparity in education processes, student outcomes and teacher working conditions must be addressed. Efficiency and innovation, rather than being commercial secrets, should be diffused and practised by all. To that end, transparency and integrity in the public education policy process need to be maintained to block vested interests. The report’s rallying call – Who chooses? Who loses? – invites policymakers to question relationships with non-state actors in terms of fundamental choices: between equity and freedom of choice; between encouraging initiative and setting standards; between groups of varying means and needs; between immediate commitments under SDG 4 and those to be progressively realized (e.g. post-secondary education); and between education and other social sectors. Supporting the fifth Global Education Monitoring Report are two online tools: PEER, a policy dialogue resource describing non-state activity and regulations in the world’s education systems; and VIEW, a new website consolidating sources and providing new completion rate estimates over time.
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