static efficiency
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Author(s):  
jifei zhao ◽  
youyang Xu

Abstract Quantum effect plays important roles in quantum thermodynamics, and recently the application of indefinite causal order to quantum thermodynamics has attracted much attentions. Based on two trapped ions, we propose a scheme to add an indefinite causal order to the isochoric cooling stroke of Otto engine through reservoir engineering. Then, we observe that the quasi-static efficiency of this heat engine is far beyond the efficiency of a normal Otto heat engine and may reach 1. When the power is its maximum, the efficiency is also much higher than that of a normal Otto heat engine. This enhancement may origin from the non-equilibrium of reservoir and the measurement on control qubit.


Author(s):  
Jie Wang ◽  
Niels P. Kruyt

Abstract Axial fans with low hub-to-tip diameter ratio are used in many branches of industry. Optimization of their aerodynamic performance is important, for which using sweep, dihedral and skew of the blades' stacking line form an important method. Investigations on axial fans with medium to high hub-to-tip diameter ratio have shown that forward sweep of blades can give improved aerodynamic performance, especially the total-to-total efficiency. However, only few studies for fans with small hub-to-tip diameter ratio have been reported. For such fans, extensive regions of backflow are present behind the fan near the hub. Based on a validated Computational Fluid Dynamics simulation method, effects of sweep, dihedral and skew in axial and circumferential directions (in forward and backward direction) on the aerodynamic performance of small hub-to-tip ratio fans are investigated, with a linear stacking line. Current results show that forward sweep and circumferential skew are beneficial for higher total-to-total efficiency and that higher total-to-static efficiency can be obtained by forward dihedral and axial skew. The backward shape variety generally gives negative aerodynamic effects. Forward sweep and circumferential skew shorten the radial migration path, but more flow separation is present near the hub. With forward dihedral and axial skew the backflow region is reduced in size and axial extent, but a more significant hub corner stall region is found. The pressure reduction due to sweep and dihedral is more limited than what could be expected from wing aerodynamics.


2021 ◽  
Author(s):  
jialu you ◽  
hang xiao

Abstract Human capital improves the efficiency of GTFP has been established in research fields, but the heterogeneous effects of human capital on GTFP and its sustainable mechanisms are unclear. This study aims to examine the effects of human capital accumulation, education fiscal, and innovation on GTFP efficiency under diversity between spatial and temporal. Employing panel data from 30 provinces from 2001 to 2018 in China, We analyzed the dynamic and static efficiency of GTFP at different regions by three-stage DEA. We explored the heterogeneous effects of human capital on GTFP through Tobit regression. Results show that the average value of GTFP efficiency is inverted U-shape and having a significant geography difference. Then, human capital accumulation and education fiscal have positive effects on the GTFP efficiency; however, innovation negatively affects GTFP efficiency. At the same time, marketization growth decreases human capital and education positive influence on the GTFP efficiency. However, this effect was not seen on the innovation—the implication of these results concerning the human capital heterogeneous effects of GTFP efficiency in a different geography. Establishing a fair and transparent system is an available choice to reduce the endowments gap and effectively promote GTFP efficiency in developing countries.


2021 ◽  
Author(s):  
Douglas A Irwin ◽  
Maksym G Chepeliev

Abstract This paper provides a quantitative general equilibrium evaluation of the repeal of Britain's Corn Laws in 1846. Using a detailed input-output matrix of the British economy in 1841, we find the abolition of Britain's tariff on imported grain left overall welfare roughly unchanged as the static efficiency gains are offset by terms-of-trade losses. Labourers and capital owners gained a slight amount at the expense of landowners. Combining these changes in factor payments with the different consumption patterns across income groups, we find that the top 10% of income earners lost while the bottom 90% of income earners gained.


2021 ◽  
pp. 283-310
Author(s):  
Victor Espinosa ◽  
William Wang ◽  
Haijiu Zhu Zhu

Israel Kirzner lays the foundations of entrepreneurship as the driving force of the market process by referring to alertness, uncertainty, and plan coordination. His approach, following the footsteps of Mises and Hayek, legitimizes entrepreneurial creativity and profit-making as the heart of the dynamic market process. He argues that an accurate insight into the economic system requires exploring how entrepreneurial dynamics work in society. This statement contrasts with the theories and models that govern modern development economics, such as randomized controlled trials (RCTs), in which the zero-intelligence agents replace the flesh-and-blood entrepreneur. Randomized controlled trials are considered the gold standard in modern development economics to assess treatment intervention efficacy in underdeveloped countries (Rodrik 2009). As a causal inference method, RCTs seek to determine whether a program had the outcome for which it was designed. Experts often utilize purely quantitative and experimental strategies for their guiding insights through trial and error of different interventions. In the ethics domain, experts seek to maximize the cost-benefit of specific interventions subject to a given set of data to rectify the inequalities generated by the market economy in underdeveloped economies. The economist becomes a kind of plumber who designs the creation and distribution of the “social pie,” assigning the respective slices to the specific individuals who participate in the experiments. Consequently, RCTs have justified active government intervention in the market process on behalf of policy advisers.However, Kirzner’s theory of entrepreneurship indicates that modern development economics’s core problem is epistemological and related to using the criterion of static efficiency in applied economics. Although RCTs are considered one of the most rigorous methods to inquire into the effectiveness of development policies, their design lacks interpretative capacity on the essence of economic phenomena. Experts on RCTs do not recognize that economic development is the byproduct of achieving social cooperation and coordination driven by purposeful human action under the division of labor. If the essence of economic phenomena is disregarded, it is impossible to address poverty causes adequately. Accordingly, RCTs are limited to testing cosmetic problems of economic underdevelopment.This article does not seek to offer specific proposals to remedy RCTs’ shortcomings, but it provides a theoretical foundation to guide further theoretical and empirical work. It argues that development economists have overlooked Kirzner’s theory of efficiency, which cannot be omitted without impairing the premise that development theory involves studying the dynamic process of plan coordination. Its relevance lies in the fact that Kirzner’s research can reshape modern development economics, which implies a theoretical advancement in several areas:• Kirzner’s analysis of static efficiency reveals the epistemological and ethical problems of modern development economics.• The framework of Kirzner’s dynamic efficiency clarifies the role of entrepreneurship in understanding how the market works.• Dynamic efficiency recognizes the creative and coordinating potential of entrepreneurship and capital accumulation in economic development.• Kirzner’s economic development theory responds to ethical dilemmas about (in)equality and pure profit within a market economy.• Contemporary research on dynamic efficiency explores new branches, such as the role of psychology, culture, and morality in economic development.Most research on efficiency and underdevelopment is still packaged in mathematical models that reduce the market’s complexity to comparative statics. Fortunately, a growing number of theories have begun to challenge this state of affairs by examining the following: First, psychology’s impact on productivity or the unproductiveness of entrepreneurial profit opportunities. Second, the role of culture in the dynamic process of institutional change and the adaptation of the entrepreneurial performance that ensures or deter economic development. Third, the relationship between personal morality and dynamic efficiency concerns private property and contractual ties. Hence, there are several strands of new literature on dynamic efficiency and development economics. This article focuses on one aspect that concerns both economists and governments in terms of modern thinking and practice: the role of efficiency (static and dynamic) in economic development.


Author(s):  
Carlo Cravero ◽  
Gabriele Milanese

Abstract The design of an industrial axial flow fan can take great advantage from the knowledge of performance limits and favourable design choices determined from its specific fluid-dynamic characteristics. As for other turbomachinery types, this fact is generally experienced through the entire design flow-path, from the preliminary design phase to the final optimization. Correlations, data and charts available from literature as well as proprietary database, exploited with many techniques (including machine learning) are resources in widespread use for this purpose. Despite the fluid dynamics of axial flow fans can be considered a well-known topic, nevertheless some specific points (e.g. the maximum achievable total-to-static efficiency) can be the subject of discussions, misunderstanding or bad design choices. The present work addresses this problem in two parts. In the first part a simple 1D model is built, for fans with and without stator, from classical theory of axial fans for pressure rise coefficient, head coefficient, flow angles and diffusion efficiency. The most relevant quantities (e.g. total-to-total efficiency, total-to-static efficiency), obtained with the 1D model, are plotted on hill charts as a function of the non-dimensional pressure rise and flow coefficient. This tool provides information that can be used for preliminary design evaluations, to understand and exploit the impact of the main design choices on the basic flow characteristics and the related performance. In the second part of the work a numerical investigation is presented on the main 3D flow characteristics that are observed to limit, both in CFD simulations and experimental tests, the performance of industrial axial fans at high-pressure rise and low-to-medium flow coefficients. Simulations results highlighted that local critical swirl ratios exist for the hub and the tip regions which, when exceeded, lead with different flow topology changes to a strong performance degradation.


Author(s):  
Z. Meiring ◽  
S. J. van der Spuy ◽  
C. J. Meyer

Abstract Axial flow fans used in air-cooled condensers are typically analysed with smooth rounded hubs as they offer superior performance when compared to other hub configurations. However, such a hub configuration is impractical and may increase the manufacturing and installation costs of air-cooled condensers. As such, it is desirable to use a simpler, yet effective, hub configuration in order to reduce the installation cost. This paper assesses the impact that a simpler hub configuration may have on the performance of an axial flow fan. This is done through a comparison of three hub configurations: a cylindrical hub with a flat nose, a cylindrical hub with a hemispherical nose, and a disk hub, installed on the B2a-fan. Computational fluid dynamics modelling, utilising OpenFOAM, is used to simulate each hub configuration. It is found that the impact on performance due to hub configuration is dependent on the volumetric flow rate through the fan. A thin disk hub exhibits superior performance at low flow rates, resulting in a 8.4% improvement in total-to-static pressure rise and a 5.7% point improvement in total-to-static efficiency. As volumetric flow rate increases, the effectiveness of the disk hub configuration reduces while the hemispherical and flat nosed cylindrical hub configurations result in similar performance metrics at the design point flow rate. At above design point flow rate, the flat nosed cylindrical hub configuration shows an improvement in performance over the hemispherical nose cylindrical hub configuration, with a 9.5% increase in total-to-static pressure rise and a 5.1% point improvement in total-to-static efficiency.


2020 ◽  
Vol 12 (11) ◽  
pp. 4361
Author(s):  
Yingyu Lu ◽  
Bo Cao ◽  
Yidi Hua ◽  
Lei Ding

Reasonably assessing the efficiency of green regional development is a key to improving environmental management and implementing sustainable development strategies. From the perspectives of environmental pollutant emissions, energy consumption, and production factor cost, the non-radial data envelopment analysis model based on the Malmquist index was applied to measure the green development efficiency and regional differences of 11 cities in Zhejiang from 2007 to 2016 from both static and dynamic aspects. This paper further analyzes the inherent influencing factors through the panel data model. The result shows: (1) The average static efficiency of green development in Zhejiang Province is 0.844. There is still 15.6% of improvement space from the frontier of production. Pollution emission management has the greatest improvement potential. Pure technical efficiency is the main factor restricting the static efficiency. (2) The dynamic efficiency of Zhejiang’s green development achieves an average annual rate of 0.26%, with a cumulative growth of 2.33%. The improvement of green development efficiency mainly depends on scale efficiency change. (3) The inherent factors affecting the efficiency of green development in the 11 cities mainly include three factors: the industrial structure, environmental regulation, and the urbanization level. The industrial structure has a positive effect, while environmental regulation and the urbanization level have negative effects. (4) The 11 cities are relatively evenly distributed in the four “static–dynamic efficiency” classification quadrants, and there is no "Matthew effect" of high–high, low–low polarization.


2020 ◽  
Vol 10 (10) ◽  
pp. 3460
Author(s):  
Kyung Jung Lee ◽  
Il Wung Park ◽  
Ki Suk Bang ◽  
Yeong Min Kim ◽  
Young Chull Ahn

We successfully designed an optimized plenum fan with a three-dimensional, smooth, curved blade. The optimized model revealed that the static pressure in the channel had been increased uniformly and stably, and the flow separation at the leading edge was significantly reduced. According to simulations, the three-dimensional blade stabilized the fluid flow, and the flow friction was reduced by suppressing the flow separation as much as possible so that both the static pressure and the static efficiency were clearly improved in comparison with those of the original model. As a result, the static efficiency was improved by 6.3% compared with that of the original model.


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