Universal Optimization Efficiency for Nonlinear Irreversible Heat Engines

2017 ◽  
Vol 42 (3) ◽  
Author(s):  
Yanchao Zhang ◽  
Juncheng Guo ◽  
Guoxing Lin ◽  
Jincan Chen
Keyword(s):  
Objective Function ◽  
Strong Coupling ◽  
Power Efficiency ◽  
Symmetry Condition ◽  
Maximum Efficiency ◽  
Cycle Model ◽  
Trade Off ◽  
Heat Engines ◽  
Optimization Efficiency ◽  
Universal Expression

AbstractWe introduce a multi-parameter combined objective function of heat engines under the strong coupling and symmetry condition and derive the universal expression of the optimization efficiency. The results obtained show that the optimization efficiency derived from the multi-parameter combined objective function include a variety of optimization efficiencies, such as the efficiency at the maximum power, efficiency at the maximum efficiency-power state, efficiency at the maximum ecological or unified trade-off function, and Carnot efficiency. It is further explained that these results are also suitable for the endoreversible cycle model of the Carnot heat engines operating between two heat reservoirs.

scholarly journals Optimization and Efficiency Studies of Heat Engines: A Review

2020 ◽  
Vol 07 (03) ◽  
pp. 37-58
Author(s):  
Preety Aneja ◽  
Keyword(s):  
Objective Function ◽  
Power Efficiency ◽  
Heat Engine ◽  
Maximum Power ◽  
Maximum Efficiency ◽  
Heat Engines ◽  
Low Dissipation ◽  
Optimization Efficiency ◽  
Efficient Power ◽  
Operating Regimes

This review aims to study the various theoretical and numerical investigations in the optimization of heat engines. The main focus is to discuss the procedures to derive the efficiency of heat engines under different operating regimes (or optimization criteria) for different models of heat engines such as endreversible models, stochastic models, low-dissipation models, quantum models etc. Both maximum power and maximum efficiency operational regimes are desirable but not economical, so to meet the thermo-ecological considerations, some other compromise-based criteria have been proposed such as Ω criterion (ecological criterion) and efficient power criterion. Thus, heat engines can be optimized to work at an efficiency which may not be the maximum (Carnot) efficiency. The optimization efficiency obtained under each criterion shows a striking universal behaviour in the near-equilibrium regime. We also discussed a multi-parameter combined objective function of heat engines. The optimization efficiency derived from the multi-parameter combined objective function includes a variety of optimization efficiencies, such as the efficiency at the maximum power, efficiency at the maximum efficiency-power state, efficiency at the maximum criterion, and Carnot efficiency. Thus, a comparison of optimization of heat engines under different criteria enables to choose the suitable one for the best performance of heat engine under different conditions.

scholarly journals Holographic heat engines coupled with logarithmic U(1) gauge theory

2021 ◽  
Author(s):  
Soodeh Zarepour
Keyword(s):  
Black Holes ◽  
Gauge Theory ◽  
Strong Coupling ◽  
Heat Engine ◽  
Positive Zero ◽  
Maximum Efficiency ◽  
Nonlinearity Parameter ◽  
Heat Engines ◽  
Ads Black Holes ◽  
Negative Constant

In this paper, we study a new class of holographic heat engines via charged AdS black hole solutions of Einstein gravity coupled with logarithmic nonlinear [Formula: see text] gauge theory. So, logarithmic [Formula: see text] AdS black holes with a horizon of positive, zero and negative constant curvatures are considered as a working substance of a holographic heat engine and the corrections to the usual Maxwell field are controlled by nonlinearity parameter [Formula: see text]. The efficiency of an ideal cycle ([Formula: see text]), consisting of a sequence of isobaric [Formula: see text] isochoric [Formula: see text] isobaric [Formula: see text] isochoric processes, is computed using the exact efficiency formula. It is shown that [Formula: see text], with [Formula: see text] the Carnot efficiency (the maximum efficiency available between two fixed temperatures), decreases as we move from the strong coupling regime ([Formula: see text]) to the weak coupling domain ([Formula: see text]). We also obtain analytic relations for the efficiency in the weak and strong coupling regimes in both low and high temperature limits. The efficiency for planar and hyperbolic logarithmic [Formula: see text] AdS black holes is computed and it is observed that efficiency versus [Formula: see text] behaves in the same qualitative manner as the spherical black holes.

Developing Schedule With Linear Programming (Case Study: STTF II Project Komplek Sukamukti Banjaran)

2020 ◽  
Vol 4 (02) ◽  
pp. 34-45
Author(s):  
Naufal Dzikri Afifi ◽  
Ika Arum Puspita ◽  
Mohammad Deni Akbar
Keyword(s):  
Linear Programming ◽  
Objective Function ◽  
Project Scheduling ◽  
Time Limit ◽  
Minimum Time ◽  
Service Cost ◽  
Trade Off ◽  
Overtime Work ◽  
The Cost

Shift to The Front II Komplek Sukamukti Banjaran Project is one of the projects implemented by one of the companies engaged in telecommunications. In its implementation, each project including Shift to The Front II Komplek Sukamukti Banjaran has a time limit specified in the contract. Project scheduling is an important role in predicting both the cost and time in a project. Every project should be able to complete the project before or just in the time specified in the contract. Delay in a project can be anticipated by accelerating the duration of completion by using the crashing method with the application of linear programming. Linear programming will help iteration in the calculation of crashing because if linear programming not used, iteration will be repeated. The objective function in this scheduling is to minimize the cost. This study aims to find a trade-off between the costs and the minimum time expected to complete this project. The acceleration of the duration of this study was carried out using the addition of 4 hours of overtime work, 3 hours of overtime work, 2 hours of overtime work, and 1 hour of overtime work. The normal time for this project is 35 days with a service fee of Rp. 52,335,690. From the results of the crashing analysis, the alternative chosen is to add 1 hour of overtime to 34 days with a total service cost of Rp. 52,375,492. This acceleration will affect the entire project because there are 33 different locations worked on Shift to The Front II and if all these locations can be accelerated then the duration of completion of the entire project will be effective

Efficiency and Industrial Democracy: The Yugoslav System

1975 ◽  
Vol 17 (4) ◽  
pp. 345-355 ◽  
Author(s):  
L. Haddad
Keyword(s):  
Economic Efficiency ◽  
Self Management ◽  
Maximum Efficiency ◽  
Industrial Democracy ◽  
Trade Off ◽  
Distinguishing Features

This paper discusses very briefly the distinguishing features of the Yugoslav system of self-management and comments on its current problems, including the alleged conflict between economic efficiency and industrial democracy. In particular, it rejects the view that the conflict is a "trade-off" problem. This view is both misleading and unrealistic. Effciency and democracy are not always incompatible, and even if they were, are not to be traded off against each other. In any case, the Yugoslavs themselves regard self-management as the supreme goal to be achieved with, but not to be sacrificed for, maximum efficiency.

scholarly journals The maximum efficiency of nano heat engines depends on more than temperature

Quantum ◽  
2019 ◽  
Vol 3 ◽  
pp. 177 ◽  
Author(s):  
Mischa P. Woods ◽  
Nelly Huei Ying Ng ◽  
Stephanie Wehner
Keyword(s):  
Second Law Of Thermodynamics ◽  
Maximum Efficiency ◽  
Second Law ◽  
Single Shot ◽  
Free Energies ◽  
Heat Engines ◽  
A Value ◽  
Quantum Protocols ◽  
Additional Constraints ◽  
Quantum Heat Engines

Sadi Carnot's theorem regarding the maximum efficiency of heat engines is considered to be of fundamental importance in thermodynamics. This theorem famously states that the maximum efficiency depends only on the temperature of the heat baths used by the engine, but not on the specific structure of baths. Here, we show that when the heat baths are finite in size, and when the engine operates in the quantum nanoregime, a revision to this statement is required. We show that one may still achieve the Carnot efficiency, when certain conditions on the bath structure are satisfied; however if that is not the case, then the maximum achievable efficiency can reduce to a value which is strictly less than Carnot. We derive the maximum efficiency for the case when one of the baths is composed of qubits. Furthermore, we show that the maximum efficiency is determined by either the standard second law of thermodynamics, analogously to the macroscopic case, or by the non increase of the max relative entropy, which is a quantity previously associated with the single shot regime in many quantum protocols. This relative entropic quantity emerges as a consequence of additional constraints, called generalized free energies, that govern thermodynamical transitions in the nanoregime. Our findings imply that in order to maximize efficiency, further considerations in choosing bath Hamiltonians should be made, when explicitly constructing quantum heat engines in the future. This understanding of thermodynamics has implications for nanoscale engineering aiming to construct small thermal machines.

TODA

2018 ◽  
Vol 10 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Cida Sanches ◽  
Samuel Ferreira Jr ◽  
Givaldo Santos ◽  
Marisa Regina Paixão ◽  
Manuel Meireles
Keyword(s):  
Decision Analysis ◽  
Objective Function ◽  
Analysis Method ◽  
Case Study Method ◽  
Application Process ◽  
Ahp Method ◽  
Trade Off ◽  
Software Application

This paper describes the use and application of the TODA (Trade-off Decision Analysis) method through a case study. The method uses the concept of trade-off applied to a prioritization matrix and, to define the weights, it takes the concept of causality into account. Studies have shown that the TODA achieves the same results as the competing AHP method. However, it is easier to operate. The methodology used is a case study concerning the choice of the type of car for a fleet of vehicles to be driven by salespeople. Together with the software application process, the methods that aided the weighting of the criteria are described and how the values of the alternatives are converted into coefficients of the objective function. The results clearly show that the method is easily applied, but the limitations of the case study method preclude forming generalizations.

scholarly journals How much do means-tested benefits reduce the demand for annuities?

2016 ◽  
Vol 16 (4) ◽  
pp. 419-449 ◽  
Author(s):  
MONIKA BÜTLER ◽  
KIM PEIJNENBURG ◽  
STEFAN STAUBLI
Keyword(s):  
Longevity Risk ◽  
Occupational Pension ◽  
Life Cycle Model ◽  
Cycle Model ◽  
Retirement Benefits ◽  
Trade Off ◽  
Administrative Dataset ◽  
Risk Insurance ◽  
The Impact ◽  
Pension Wealth

AbstractMeans-tested retirement benefits create incentives to cash out pension wealth. Individuals trade off the advantages from annuitization, receiving longevity risk insurance, to the disadvantages, giving up ‘free’ wealth in the form of means-tested supplemental income. We quantify the impact of means-tested benefits with a calibrated life-cycle model, demonstrating that they substantially reduce the desire to annuitize especially for low and intermediate levels of pension wealth. Using an administrative dataset on pension choices, we show that the model's predicted fraction of retirees choosing the annuity is able to match the annuitization pattern of occupational pension wealth observed in Switzerland. On the base of our model, we also assess alternative policies such as mandatory annutization and tougher asset tests.

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