Criteria For Evaluation Of Efficiency Research Articles

Criteria for evaluation of quality and efficiency of education in the conditions of distance learning

Criteria for evaluation of quality and efficiency of education in the conditions of distance learning

Form-finding and shape optimization of bio-inspired branching structures based on graphic statics

Structure’s internal force transfer efficiency is the bases of pursuing the creative structural form. This paper reveals the mechanical mechanisms of the bio-inspired branching structures and further presents a numerical form-finding and shape optimization method for bio-inspired branching structures based on graphic statics with the constraints of strength, stiffness of boundary conditions are considered. Efficient structural form is obtained by connecting the internal force equilibrium and the structural performance in designing process. The reciprocal diagrams in graphic statics are used to solve the form-finding problem to generate compression or tension-only tree-like structure. Establishing the formula of the evaluation criteria of internal force transfer efficiency to characterize the structural performances, the criteria is compared with the continuum topology optimization method, the shape of tree-like structure is optimized by maximizing the structural efficiency under static loads. As a result, suitable external constraints can make a structure efficient and improve the structural redundancy, material properties determine the structural form, which in turn affects the structural behavior. Consequently, the interrelation mechanisms between material-property, structural-form, and structure-performance of the highly efficient bio-inspired branching structures are found. The internal force transfer efficiency and the strength and stiffness of boundary condition are the main factors to determine the optimal solution in the topological design exploration of load-bearing structure, these factors could be controlled to obtain the effective and elegant structural form for practical fabrication. The proposed numerical method could provide intuitive understanding and real-time feedback for the optimal solution, avoid the single solution obtained by the conventional optimization techniques and limited control to modify the output topology. Besides, more structural performance (e.g. buckling, vibration) can be considered in the structural designing process.

Experimental Research of Technology for Strengthening Reinforced Concrete Columns with Carbon Fibers

Reinforcement of columns (piers) is usually accomplished by increasing cross-section through building-up, injecting reinforcing solutions and external reinforcement. The most and progressive method for strengthening is currently external reinforcement, its essence is to glue high-strength sheets, plates or strips (lamellas) onto structure surface with the help of special adhesives. Scientists pay special attention to theoretical and experimental studies of design solutions for external reinforcement of vertical load-bearing structures. Unfortunately, the results of such studies, for example, influence of technology for execution of works on strengthening efficiency are virtually absent. Therefore, the objective of this paper is to carry out experiments with the purpose to study influence of technological factors on efficiency in strengthening of reinforced concrete structures, which absorb compressive forces. The experimental studies have been made in six series that changed the technology of executed works while using various technological factors. Among the main factors are the following: presence/absence of acute angles; preparation of a base (surface coating); method for gluing reinforcing materials to a structure. A criterion for evaluation of technology efficiency has been breaking strength for axial compression of reinforced samples. Analysis on the results of experimental studies has shown that the highest load-bearing capacity is achieved while using samples of columns with rounded edges, provided that an adhesive is applied to sample base and carbon fiber (40.6 tons). The compressive strength of such samples is by 82.2 % higher than the strength of control samples. The strength of reinforced specimens with non-rounded edges has appeared to be the lowest one, namely 34.0 tons. Strengthening of the samples with fiber impregnated with an adhesive has increased the indicator by 74.3 % compared to the control samples. The compressive strength of samples reinforced with carbon fiber adhered to the adhesive which is preliminary spread on the basis is equal to 38.6 tons, which is by 73.4 % higher than the strength of the control samples.

A study on flow and heat transfer characteristics of a constructal bifurcation filler in the circular tube

Porous media are applied extensively in energy systems. However, the large flow resistance caused by porous media restricts the energy utilization and conversion efficiency. To reduce flow resistance, a constructal bifurcation filler was proposed as an alternative to the porous media filler based on constructal concept and fluid disturbance intensification idea. The two fillers were fitted in the circular tubes to investigate and compare their thermo-hydraulic characteristics. The fluid flow and heat transfer mechanisms of the two types of tubes were analyzed. The fluid disturbance intensification is the dominant mechanism of the heat transfer enhancement in the tube with the constructal bifurcation filler. Moreover, the flow resistance of the tube with the constructal bifurcation filler is decreased significantly, by 78.51–93.33%, compared to the tube with the porous media filler. Meanwhile, in contrast to the traditional fluid disturbance intensification elements, an excellent temperature uniformity similar to that of porous media is obtained for the constructal bifurcation filler. Furthermore, the efficiency evaluation criteria value is 3.66–8.77. Thus, the constructal bifurcation filler was demonstrated to exhibit superior comprehensive performance and is an effective solution for diminishing the flow resistance and improving the energy utilization efficiency. Finally, the effects of structure parameters, such as the wire mesh pitch s and inclined angle α, on the thermo-hydraulic performance of the tube with the constructal bifurcation filler were investigated.

Conjugate heat transfer enhancement in the mini-channel heat sink by realizing the optimized flow pattern

Mini-channel heat sinks are popular in cooling high heat flux devices due to the high convective heat transfer performance associated with moderate pressure drop penalty. It is of great significance to further improve the thermal hydraulic performance in the mini-channel heat sink so as to adapt it to higher heat flux conditions. In this paper, a new method of realizing the optimized flow field to enhance the thermal hydraulic performance was carried out successfully in the mini-channel heat sink. The chosen mini-channel heat sink was 30 mm × 30 mm in substrate size with Reynolds number ranging from 100 to 1100. Through conjugate heat transfer optimization based on exergy destruction minimization principle, the optimized flow pattern was characterized by three pairs of longitudinal swirls flow. Subsequently, the inclined parallelepiped ribs were proposed to realize the optimized flow pattern in the mini-channel heat sink. The heat transfer enhancement mechanism was investigated by analyzing velocity distributions, temperature distributions, and heat convection intensity. Besides, the total thermal resistance was decreased and the exergy destruction minimization principle was verified. As a result, the variation ranges of Nu/Nu0, f/f0, efficiency evaluation criterion (EEC), and overall performance criterion (R3) were 1.35–5.92, 1.27–8.75, 0.68–1.12, and 1.31–4.22, respectively. The maximum average heat flux could achieve 3.2 × 106 W/m2 within a temperature difference of 60 K between substrate and fluid. The configured parameters pitch ratio (PR) and width ratio (WR) were recommended as 1 and 0.2, respectively. This work is conducive to the structural design of mini-channel heat sinks.

Criteria for evaluation of efficiency of using machines in agricultural complex

Criteria for evaluation of efficiency of using machines in agricultural complex

Analysing thermal-hydraulic performance and energy efficiency of shell-and-tube heat exchangers with longitudinal flow based on experiment and numerical simulation

In this study, diverse baffled longitudinal flow shell-and-tube heat exchangers (STHX) are contrasted with segmental baffle shell-and-tube heat exchanger (SG-STHX). Experimental data are obtained with municipal water served as the working fluid, and the shell-side volume flow rate ranges from 1.79 m3/h to 7.42 m3/h. The components of the shell-side pressure drop are discussed stand on different flow patterns. The maximum proportion of pressure drop in tube bundle section of rod baffle shell-and-tube heat exchanger (RB-STHX) is 12%, while it has nearly taken up 70% shell-side pressure drop for both SG-STHX and large-and-small hole baffle shell-and-tube heat exchanger (LSHB-STHX). The energy efficiency of three tested STHXs is deliberated from three perspectives, including entropy generation, exergy destruction, and efficiency evaluation criterion. The longitudinal flow pattern performed superior energy efficiency, particularly for RB-STHX with the least irreversible energy loss and the most available work. Grounded on the energy-saving potential of RB-STHX, further numerical simulations on the shell-side thermo-hydraulic performance of RB-STHX are conducted. The nexus between geometrical parameters of RB-STHX and its thermal-hydraulic performance are studied. The thermal-hydraulic performance and energy efficiency discussed in this study support further design and application of longitudinal flow STHX to retain inherent superiorities with advanced performance.

Trade-off between wire matrix and twisted tape: SOLTRACE® based indoor study of parabolic trough collector

Heat transfer augmentation using turbulators in PTC is well known. However, based on the methodology its thermo-hydraulic rating can vary. In the present experimental study, variations of wire matrix and twisted tape have been used to analyse the thermo-hydraulic behavior of the PTC by referring two approaches viz. thermo-hydraulic efficiency and performance evaluation criterion. An innovative method comprising, analytical model-SOLTRACE®- differential resistance heating is incorporated to simulate the highly non-uniform solar irradiance over the receiver in an indoor test rig. Under the same operating condition, thermo-hydraulic efficiency of medium dense wire matrix is maximum whereas twisted tape of twist ratio 3.37 yields better result as per performance evaluation criterion. However, thermo-hydraulic efficiency based analysis is recommended due to the role of realistic pumping power. Further, variation in energy parameters viz. thermal efficiency, pumping power, Nusselt number and their effect on receiver length have been analyzed. The trade-off between two inserts is also discussed with respect to operating condition.

Evaluation criterion of different flow field patterns in a proton exchange membrane fuel cell

Flow field plays an important role in the design and application of proton exchange membrane fuel cell (PEMFC). The superiority of flow field is commonly evaluated by comparing the performance improvement of PEMFC. However, it’s necessary to decrease the flow resistance to reduce the parasitic power and to obtain more uniform water and gas distributions during operation. As a consequence, the combined effect of performance and resistance should be considered during the optimal design of flow channel in PEMFC. A new criterion of efficiency evaluation criterion (EEC) using Sherwood number and Euler number has been proposed to evaluate the relationship between the mass transfer and the pressure drop in this study. The performances of PEMFCs with parallel, single-serpentine, and pressured parallel flow fields are investigated in detail. The results show that PEMFC with single-serpentine flow field has a better performance under normal atmospheric pressure, while the pressure drop in cathode is much larger than that in the parallel flow field. The pressured parallel flow field presents better performance and uniform gas distribution and it is thus proposed as the flow channel in the application of PEMFC.

Constructal design progress for eight types of heat sinks

This review paper summarizes constructal design progress performed by the authors for eight types of heat sinks with ten performance indexes being taken as the optimization objectives, respectively, by combining the methods of theoretical analysis and numerical calculation. The eight types of heat sinks are uniform height rectangular fin heat sink, non-uniform height rectangular fin heat sink, inline cylindrical pin-fin heat sink (ICPHS), plate single-row pin fin heat sink (PSRPHS), plate inline pin fin heat sink (PIPHS), plate staggered pin fin heat sink (PSPHS), single-layered microchannel heat sink (SLMCHS) with rectangular cross sections and double-layered microchannel heat sink (DLMCHS) with rectangular cross sections, respectively. And the ten performance indexes are heat transfer rate maximization, maximum thermal resistance minimization, minimization of equivalent thermal resistance which is defined based on the entransy dissipation rate (equivalent thermal resistance for short), field synergy number maximization, entropy generation rate minimization, operation cost minimization, thermo-economic function value minimization, pressure drop minimization, enhanced heat transfer factor maximization and efficiency evaluation criterion number maximization, respectively. The optimal constructs of the eight types of heat sinks with different constraints and based on the different optimization objectives are compared with each other. The results indicated that the optimal constructs mostly are different based on different optimization objectives under the same boundary condition. The optimization objective should be suitable chosen based on the focus when the constructal design for one heat sink is performed. The results obtained herein have some important theoretical significances and application values, and can provide scientific bases and theoretical guidelines for the thermal design of real heat sinks and their applications.

Experimental investigation of the receiver of a solar thermal dish collector with a dual layer, staggered tube arrangement, and multiscale diameter

A new experimental model is proposed and tested to enhance the ability of receivers of solar thermal dish collectors in absorbing solar energy. An innovative model consisting of a dual layer, staggered arrangement, and multiscale diameter tubes is established. The enhancement augments the capability of the solar receiver of the collector to transform solar energy to thermal energy within the heat transfer fluid. The new design depends on the exploitation of the dead regions of the solar receiver, that is, surfaces with weak solar energy absorption which include the space between the pipes and the terminal sides of the pipes. The surface areas of the circular pipes in these regions are almost parallel to the solar energy radiation, which leads to a reduction in the ability of the tube to absorb solar energy. The design was validated through five receiver ([Formula: see text]) models for solar thermal dish collectors, in addition to the model base (which has single layer). Each model consists of a two-layer staggered arrangement and tubes with four different staggered diameter ratios [Formula: see text] between the two layers. Each of them has an octagonal shape and consists of three serial paths of copper tubes; each path consists of a bank of parallel tubes. The results show a noteworthy increase in the ability of the receiver to absorb solar energy and greater with model ([Formula: see text]) which [Formula: see text]equal (0.269) than for a plain tube collector. The enhancement leads to an increase in the thermal efficiency [Formula: see text]and exergetic performance [Formula: see text], that equal (78.8%) and (19.8%) respectively at (0.07 kg/s). Furthermore, the pressure difference, and efficiency evaluation criterion was estimated to evaluate dish collector receivers.

Automatization and information technologies development for monitoring and evaluation of penitentiary healthcare facilities efficiency

The article presents an algorithm for developing a software package for evaluation of penitentiary healthcare facilities efficiency. The algorithm is based on the data of penitentiary healthcare facilities of the Volga Federal District. To create a computer program algorithm there were chosen indicators and criteria for evaluation of penitentiary health facilities efficiency. Mathematical processing of indicators based on the Analytic Hierarchy Process allows to present the formula for calculating the total integral indicator, which is calculated automatically. The results of calculation are presented in the window interface of the computer program in the form of color charts. In this way it forms a rating of healthcare facilities, where green indicates high level of efficiency, yellow indicates its medium level, red indicates its low level.

Criteria for evaluation of efficiency of actions, directed to decrease in burden of tuberculosis at present stage in Russia

Parameters in which it is necessary to estimate efficiency of the held anti-epidemic events in the territory directed to decrease in a burden of TB at the present stage.

Land Resources of Alagirskii District As a Factor of Sustainable Development of the Agro-industrial Complex

The most important condition for the rational organization of the territory is the formation of a morphological appearance, which is distinguished by high productivity, ecological diversity, aesthetic appeal, and will satisfy sanitary and hygienic requirements. The use of land resources in the Alagirskii District of the Republic of North Ossetia-Alania and the development of measures for rational organization of the territory, with the creation of an effective system of land use, evaluation criteria of environmental reliability, social acceptability, economic efficiency and compliance with the legal regime of land use, are a necessary condition for the rational use of land. In this work, materials of land inventory for 2016–2018, data of the committee of land and property relations of the district, statistical data on the effectiveness of agricultural land were used. The developed data allows to establish the optimal ratio of natural ecosystems and agro-ecosystems for this natural-agricultural zone, to establish optimal areas of arable and forage lands that need improvement based on the landscape features of the territory for stability and development of agricultural production.

Data envelopment analysis models for the assessment of efficiency of sustainable forest management in Poland

Abstract The aim of the presented research was to analyse the efficiency of forest management as an approach to promote sustainable multifunctional forestry. A total of 17 Regional Directorates of State Forests (RDSFs) in Poland were studied with the use of data envelopment analysis (DEA). This method has been proposed and tested using criteria and indicators (C&Is) as inputs and outputs of the created models. The research process was divided into two stages: first, we analysed the efficiency of simple DEA models and models with additional variables, which allowed us to determine the major models providing the best combination of efficiency evaluation criteria. Second, we used these models to assess the efficiency of sustainable management of forests by RDSFs. According to our results, RDSFs were found to be highly efficient in converting resources into production and nonmarket results. Nevertheless, the implementation of sustainable development principles requires further actions, in order to fulfil all ecological, economic, and social functions in a more effective way. They are connected with the necessity to increase the areas of both protective forests and promotional forest complexes. Thus, the results of this study might be a valuable source of information for the planning process of forestry services at the strategic and operational levels.

Problems and prospects for evaluating the effectiveness of scientific activity in the chemical-technological field

In modern conditions, the nature of scientific activity in the chemical and technological field is changed radically. Therefore, it is particularly relevant to implement an effective scientific and technical policy in this area in order to reduce the level of risk of the negative impact of hazardous chemical factors on the population and the environment. For a deeper understanding of the problems associated with the evolution of research and development in the chemical-technological field, the development of the issues of determining the effectiveness of scientific activity was applied in relation to the assessment of basic and applied research. The features of the development of science in the chemical-technological field in modern conditions are highlighted. A review of methods for determining the effectiveness of research and development is presented, and methodological problems are discussed. The specificity of determining the effectiveness of fundamental and applied scientific research in the chemical and technological field is highlighted. The problems of operational and long-term planning of research and development are investigated. The features of the expansion of research in the field of chemical technology are revealed. The problems of increasing the resource-intensiveness of research and development, staffing and optimization of training mechanisms for graduates of rare specialties in the chemical-technological field are investigated. Scientific and methodological approaches are proposed for determining the effectiveness of scientific activity in the chemical and technological field. Efficiency evaluation criteria are developed, which take into account the internal effects and externalities of scientific activities in the chemical and technological field. Efficiency is proposed to be evaluated according to three groups of criteria, internal efficiency, external efficiency and structural efficiency. Since the main part of the information can only be obtained through examination, the problems of obtaining and processing expert information are highlighted and ways of solving them are outlined.

A Review of the Enhancement of Bio-Hydrogen Generation by Chemicals Addition

Bio-hydrogen production (BHP) produced from renewable bio-resources is an attractive route for green energy production, due to its compelling advantages of relative high efficiency, cost-effectiveness, and lower ecological impact. This study reviewed different BHP pathways, and the most important enzymes involved in these pathways, to identify technological gaps and effective approaches for process intensification in industrial applications. Among the various approaches reviewed in this study, a particular focus was set on the latest methods of chemicals/metal addition for improving hydrogen generation during dark fermentation (DF) processes; the up-to-date findings of different chemicals/metal addition methods have been quantitatively evaluated and thoroughly compared in this paper. A new efficiency evaluation criterion is also proposed, allowing different BHP processes to be compared with greater simplicity and validity.

An Innovative Receiver Design for a Parabolic Trough Solar Collector Using Overlapped and Reverse Flow: An Experimental Study

A new technique was proposed and implemented through an experimental model to improve the absorber tube of a parabolic trough collector, which was connected to a twisted tube and resulted in a heat transfer enhancement. The enhancement increased the capacity of the tube to absorb solar energy by improving the convective transfer between the inner surface of the absorber tubes and the heat transfer fluid. The new design was dependent on overlapped and reverse flow, which was validated through five receiver tube $$(R_\mathrm{t})$$ models, each one consisting of two types of overlapped flows. The first was a flow through inner twisted tubes (single (STT), dual (DTT), and triple (TTT) twisted tubes), with different hydraulic diameters. The second was a reverse flow through an outer round tube, with both concentric tubes joined at one side by a bayonet end cap. For each $$R_\mathrm{t}$$, the inlet flow from the central or peripheral tubes was assessed. The results showed a remarkable increase in heat transfer enhancement for most STT models and a greater heat transfer in TTT that was overlapped than for a plain tube collector. The enhancement was accompanied by an increase in the pressure difference that was higher for TTT than STT. For each model, the efficiency of the collector and pressure losses was estimated, and the Nusselt number (Nu) and an efficiency evaluation criterion were calculated.

Methods, procedures and tools for diversification of enterprises and organizations of the Russian defense industry

Purpose: the work covers the issues of organizational, methodological and instrumental support of the processes of diversification of organizations and enterprises of the Russian defense industry complex. Based on an analysis of the reasons for the low efficiency of federal targeted programs for the conversion of enterprises and the organization of the military-industrial complex in 1993-1997, proposals for its improvement were formulated.Methods: the methodological basis of the approach considered in the article is to assess the effectiveness of diversification, including both parameters of the use of production capacity and the main results of the production activities of economic entities.Results: the article proposed and justified: 1) the principles of diversification of enterprises and defense industry organizations; 2) tools for assessing the economic consequences, based on justifying calculations of the use of production capacity, determining the need for resources, the volume of capital investments and production areas; 3) action plan (“roadmap”) for the development and production of high-tech civilian products.Conclusions and Relevance: Diversification of enterprises and organizations of the defense-industrial complex of the Russian Federation in most cases (except for dual-use products) requires an investment of a considerable amount of funds. In order to ensure the minimization of the resources required for its fulfillment (amount of capital investments, production space and labor force), the use of the production potential load factor is proposed as a criterion for evaluation of conversion efficiency of military production.

Stormwater Utility Fees and Credits: A Funding Strategy for Sustainability

Lack of stable and dedicated funding has been a primary challenge for municipalities in the United States to implement effective stormwater management programs. Stormwater utility fees (SUFs), as user fees, are an alternative dedicated revenue source to fund stormwater management. When complemented with stormwater utility credits or discounts, SUFs provide greater flexibility to adopting best management practices and reducing stormwater runoff at a lower overall cost to the community. While SUFs have been increasingly used, there is little systematic research on this topic. This paper reviews literature on how SUFs work, discusses the mechanisms for setting the fees, and provides examples of different rate structures from across the U.S. Then, we use the findings of the literature to evaluate SUFs as a funding strategy for stormwater management based on four revenue evaluation criteria of efficiency, equity, revenue adequacy, and feasibility. Overall, the literature indicates that stormwater utility fees are a more efficient and environmentally sustainable source of revenue that allows for long-range planning of capital improvements and operations, but their high political visibility and legal obstacles can affect their effective implementation. However, more empirical research is needed to assess these propositions. There is a lack of literature on effective SUF designs, equitable fee types, the extent to which SUFs lead to change in public behavior and their impact on business and stormwater management investments in a municipality.