Search

The energy dissipation in the lifecycle of gearboxes is often dominated by the use phase. Energy efficiency targets can accelerate technological development. For tribological contacts, the definition of superlubricity with coefficients of friction of less than 0.01 has stimulated research to reduce friction. Similarly, this potential study on the energy efficiency of gearboxes aims to push research to reduce their energy dissipation during the use phase. Different cylindrical gear geometries, gear oils, and lubrication methods are evaluated using an energy efficiency index and mean energy efficiency. Superefficiency is allocated to the technological setup of a water-containing polyglycol, an extreme low-loss gear, and minimum quantity lubrication. Its corresponding values for the energy efficiency index and mean energy efficiency depend on the particular gearbox and the underlying operating cycle. In the future, the method used in this study can be used to introduce energy classes for gearboxes and to assign energy labels. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The study assesses the spatial efficiency of Romania's counties and development regions from the perspective of sustainable development. Data Envelopment Analysis (DEA) was used to calculate spatial efficiency, and A-P model (Andersen and Petersen) was used to rank efficient units (those with a score of 1.000) to assess superefficiency. The results of the study are graphically translated into four maps. The average efficiency of Romania's counties is 0.945 and the average efficiency of development regions is 0.986. Almost all development regions are efficient, with the only inefficient region being the Sud-Est region (0.887). The development regions with the highest superefficiency scores are located in the western part of Romania. The highest score of superefficiency is registered by the București-Ilfov region (30.997), the capital of the country and its surroundings, the economic engine of Romania. [ABSTRACT FROM AUTHOR]

Abstract This study used the superefficiency direction distance function and total factor energy efficiency to evaluate the changes in energy efficiency and total factor energy efficiency of 11 member countries of the Comprehensive and Progressive Agreement for Trans‐Pacific Partnership (CPTPP) from 2013 to 2017. Based on the results, we consider the policy implications for CPTPP members, and suggest approaches to improve the direction and range of the difference variable for aalyzing energy efficiency performance. In the selection of variables, input variables include labor force, energy consumption, and capital formation; undesirable output variables include the domestic production gross, life expectancy, and PM2.5. The results show that Canada, Japan, and Mexico have the best performance in terms of energy superefficiency and total factor energy efficiency; in contrast, Chile, Malaysia, Peru, and Vietnam would benefit from improved energy efficiency. Energy efficiency can be improved by reducing labor and final energy consumption, increasing gross domestic product, and reducing PM2.5. However, simultaneously improving all three factors is challenging. Countries should first focus on appropriately adjusting energy policies, actively developing new energy use, improving production technology, avoiding waste, reducing PM2.5, and accelerating urban development to achieve optimal energy efficiency.

In the evaluation scenario with undesirable outputs, the SBM-Undesirable model is usually used together with the SuperSBM-Undesirable model to fully differentiate efficient and inefficient decision-making units (DMUs). The existing SuperSBM-Undesirable model has two main forms, but both have problems in implementation. One form may be infeasible under the variable returns to scale (VRS); Another form has an inappropriate definition for undesirable output efficiency. These two problems are seriously ignored in the existing applications. In this paper, we first propose an improved SuperSBM-Undesirable model with strongly efficient projections, which is feasible under the constant returns to scale (CRS) or VRS technology. Then, by integrating the SBM-Undesirable and the improved SuperSBM-Undesirable models, we focus on proposing a concise, precise and practical one-stage model considering undesirable outputs to differentiate all DMUs and determine their strongly efficient projections simultaneously. The proposed one-stage model only contains essential decision variables and constraints, thereby effectively conserving computational time for large-scale practical applications. Further, by introducing the weighting preference of inputs and outputs, we construct the one-stage model with weighting preference to differentiate the importance of different indicators. Finally, through several data experiments, the superiority of our models in computational results and computational scale are verified. [ABSTRACT FROM AUTHOR]

This study used the superefficiency direction distance function and total factor energy efficiency to evaluate the changes in energy efficiency and total factor energy efficiency of 11 member countries of the Comprehensive and Progressive Agreement for Trans‐Pacific Partnership (CPTPP) from 2013 to 2017. Based on the results, we consider the policy implications for CPTPP members, and suggest approaches to improve the direction and range of the difference variable for aalyzing energy efficiency performance. In the selection of variables, input variables include labor force, energy consumption, and capital formation; undesirable output variables include the domestic production gross, life expectancy, and PM2.5. The results show that Canada, Japan, and Mexico have the best performance in terms of energy superefficiency and total factor energy efficiency; in contrast, Chile, Malaysia, Peru, and Vietnam would benefit from improved energy efficiency. Energy efficiency can be improved by reducing labor and final energy consumption, increasing gross domestic product, and reducing PM2.5. However, simultaneously improving all three factors is challenging. Countries should first focus on appropriately adjusting energy policies, actively developing new energy use, improving production technology, avoiding waste, reducing PM2.5, and accelerating urban development to achieve optimal energy efficiency. [ABSTRACT FROM AUTHOR]

The oracle property of model selection procedures has attracted a large volume of favorable publications in the literature, but also faced criticisms of being ineffective and misleading in applications. Such criticisms, however, have appeared to be largely ignored by the majority of the popular statistical literature, despite their serious impact. In this paper, we present a new type of Hodges' estimators that can easily produce model selection procedures with the oracle and some other desired properties, but can be readily seen to perform poorly in parts of the parameter spaces that are fixed and independent of sample sizes. Consequently, the merits of the oracle property for model selection as extensively advocated in the literature are questionable and possibly overstated. In particular, because the mathematics employed in this paper are at an elementary level, this finding leads to new discoveries on the merits of the oracle property and exposes some overlooked crucial facts on model selection procedures. [ABSTRACT FROM AUTHOR]

Recent approaches in causal inference have proposed estimating average causal effects that are local to some subpopulation, often for reasons of efficiency. These inferential targets are sometimes data-adaptive, in that they are dependent on the empirical distribution of the data. In this short note, we show that if researchers are willing to adapt the inferential target on the basis of efficiency, then extraordinary gains in precision can potentially be obtained. Specifically, when causal effects are heterogeneous, any asymptotically normal and root-n$n$ consistent estimator of the population average causal effect is superefficient for a data-adaptive local average causal effect.

In the present paper we derive lower asymptotic information bounds of Cramér-Rao type for estimators of nonparametric statistical functionals. The results are based on dense differentiability and dense regularity concepts which lead to weak assumptions. As explicit examples L-estimators are treated. In addition a new rapid method for the treatment of survival functionals under randomly right censored data is presented. For instance, for the famous Kaplan-Meier and Nelson-Aalen estimators, our information bound is just the lower bound obtained earlier in the literature. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to evaluate the efficiency of glass firms in India. Design/methodology/approach – Data envelopment analysis (DEA) has been employed to study the technical, scale and superefficiency measures of glass firms in India. Findings – Major findings of DEA analysis show that 65 percent firms are found to be technically efficient. Returns to scale analysis indicate that five firms are operating at decreasing returns to scale and two firms are exhibiting increasing returns to scale. Further, results show that small- and medium-scale firms are more efficient than large-scale firms. Old firms are more efficient compared to the young firms and foreign-owned firms are technically more efficient compared to the domestic firms. Practical implications – The results of this study would help the managers to assess their relative efficiency and take corrective measures to efficiently use their resources. Originality/value – This seems to be the first study to apply DEA to analyze the efficiency of glass firms in India. No previous study on glass industry seems to have decomposed the measure of overall technical efficiency into its components, namely, pure technical efficiency and scale efficiency and no study seems to have examined whether ownership, age and size of a firm are significant for its efficiency. In addition, no earlier study seems to have ranked the glass firms based on their efficiency values. Further, target values of inputs and outputs are demonstrated in this study. Stability of efficiency scores is also checked. [ABSTRACT FROM AUTHOR]

The second-level digital divide, which focuses on skills and usage, calls for a rethink of conventional indices developed for measuring access to technology. We propose a superefficiency data envelopment analysis (DEA) framework to investigate Internet users’ online activity at an individual level by considering their access to information and communication technology (ICT), Internet literacy, and level of usage, and we offer a standard basis for measuring and comparing ICT users. We apply an ordinary least squares regression to explore the factors that influence users’ online activities. Our results show that Internet users who are female, older, less educated, not in white-collar positions, earning a higher monthly income, and living in nonurban areas are more active online when all online activities are considered at the same time. However, the factors that influence individual online activities are different. [ABSTRACT FROM PUBLISHER]

In some estimation problems, especially in applications dealing with information theory, signal processing and biology, theory provides with additional information allowing us to restrict the parameter space to finite number of points. In this case, we speak of discrete parameter models Even though the problem is quite old and has interesting connections with testing and model selection, asymptotic theory for these models has hardly ever been studied. Therefore, we discuss consistency, asymptotic distribution theory, information inequalities and their relations with efficiency superefficiency for a general class of m-estimators. [ABSTRACT FROM AUTHOR]

Using a new method based on generalized sections of feasible sets, we obtain optimality conditions for vector optimization of objective multifunctions with multivalued constraints. [ABSTRACT FROM AUTHOR]

This paper extends Imbens and Manski's (2004) analysis of confidence intervals for interval identified parameters. The extension is motivated by the discovery that for their final result, Imbens and Manski implicitly assumed locally superefficient estimation of a nuisance parameter. I reanalyze the problem both with assumptions that merely weaken this superefficiency condition and with assumptions that remove it altogether. Imbens and Manski's confidence region is valid under weaker assumptions than theirs, yet superefficiency is required. I also provide a confidence interval that is valid under superefficiency, but can be adapted to the general case. A methodological contribution is to observe that the difficulty of inference comes from a preestimation problem regarding a nuisance parameter, clarifying the connection to other work on partial identification. [ABSTRACT FROM AUTHOR]

In 1952 Lucien Le Cam announced his celebrated result that, for regular univariate statistical models, sets of points of superefficiency have Lebesgue measure zero. After reviewing the turbulent history of early studies of superefficiency, I suggest using the notion of computability as a tool for exploring the phenomenon of superefficiency. It turns out that only computable parameter points can be points of superefficiency for computable estimators. This algorithmic version of Le Cam's result implies, in particular, that sets of points of superefficiency not only have Lebesgue measure zero but are even countable. [ABSTRACT FROM AUTHOR]

Abstract: The connections between information pooling and adaptability as well as superefficiency are considered. Separable rules, which figure prominently in wavelet and other orthogonal series methods, are shown to lack adaptability; they are necessarily not rate-adaptive. A sharp lower bound on the cost of adaptation for separable rules is obtained. We show that adaptability is achieved through information pooling. A tight lower bound on the amount of information pooling required for achieving rate-optimal adaptation is given. Furthermore, in a sharp contrast to the separable rules, it is shown that adaptive non-separable estimators can be superefficient at every point in the parameter spaces. The results demonstrate that information pooling is the key to increasing estimation precision as well as achieving adaptability and even superefficiency. [Copyright &y& Elsevier]

In the framework of locally convex topological vector spaces, we establish a scalarization theorem, a Lagrange multiplier theorem and duality theorems for superefficiency in vector optimization involving nearly subconvexlike set-valued maps. [ABSTRACT FROM AUTHOR]

At a superficial level, the idea of maximum likelihood must be prehistoric: early hunters and gatherers may not have used the words "method of maximum likelihood" to describe their choice of where and how to hunt and gather, but it is hard to believe they would have been surprised if their method had been described in those terms. It seems a simple, even unassailable idea: Who would rise to argue in favor of a method of minimum likelihood, or even mediocre likelihood? And yet the mathematical history of the topic shows this "simple idea" is really anything but simple. Joseph Louis Lagrange, Daniel Bernoulli, Leonard Euler, Pierre Simon Laplace and Carl Friedrich Gauss are only some of those who explored the topic, not always in ways we would sanction today. In this article, that history is reviewed from back well before Fisher to the time of Lucien Le Cam's dissertation. In the process Fisher's unpublished 1930 characterization of conditions for the consistency and efficiency of maximum likelihood estimates is presented, and the mathematical basis of his three proofs discussed. In particular, Fisher's derivation of the information inequality is seen to be derived from his work on the analysis of variance, and his later approach via estimating functions was derived from Euler's Relation for homogeneous functions. The reaction to Fisher's work is reviewed, and some lessons drawn. [ABSTRACT FROM AUTHOR]

In the framework of normed spaces, Borwein and Zhuang introduced superefficiency and gave its concise dual form when the underlying decision problem is convex. In this paper, we consider four different generalizations of the Borwein and Zhuang superefficiency in locally convex spaces and give their concise dual forms for convex vector optimization. When the ordering cone has a base, we clarify the relationship between Henig efficiency and the various kinds of superefficiency. Finally, we show that whether the four kinds of superefficiency are equivalent to each other depends on the normability of the underlying locally convex spaces. [ABSTRACT FROM AUTHOR]

It is widely recognized that general practitioners (GPs) play a key role in determining the use of resources for ambulatory care. In addition to the GPs' working hours, these resources consist of the work of specialists and that of hospital physicians treating the GPs' referrals and the cost of medication and other measures induced by the GP. Different systems of remuneration differ in their power to lead to efficient service provision. This contribution provides empirical evidence on the efficiency of service provision by Austrian GPs. The analysis is based on data for some 600 GPs. The data comprise sufficient information to assess the GPs' efficiency with regard to the way they manage their cases. Data Envelopment Analysis, a nonparametric technique, is used to estimate the production frontier. The results suggest that almost one-half of the GPs in the sample have a relative efficiency of 0.8 or less. A Malmquist decomposition of the productivity change reveals a decline in productivity. This is due to a pronounced negative shift of the frontier whereas individual efficiency rises against the weaker benchmark of the new frontier. [ABSTRACT FROM AUTHOR]

We reduce the definitions of proper efficiency due to Hartley, Henig, Borwein, and Zhuang to a unified form based on the notion of a dilating cone, i.e., an open cone containing the ordering cone. This new form enables us to obtain a comprehensive comparison among these and other kinds of proper efficiency. The most advanced results are obtained for a special class of proper efficiencies corresponding to one-parameter families of uniform dilations. This class is sufficiently wide and includes, for example, the Hartley and Henig proper efficiencies as well as superefficiency. [ABSTRACT FROM AUTHOR]