Efficiency Criteria Research Articles

Development of a creative digital curriculum for the elderly: A participatory approach to enhance potential for alternative career opportunities in the digital era

This research aimed to develop a curriculum for empowering the elderly to create alternative careers in the digital society era through digital platforms and to study the effects of the curriculum and online educational channels on enhancing the elderly’s capabilities. Participatory Action Research (PAR) methods combined with qualitative and quantitative approaches were employed in this study. The study involved 555 participants including personnel and elderly individuals in Lampang Province that were selected by using multi-stage sampling. Descriptive statistics were used to analyze the data and compare the group mean by t-test. The research findings revealed that the “Creative Digital Retirees” curriculum for empowering the elderly to use digital technology, digital media literacy and utilizing digital media to create alternative careers met the effective criteria, the 80/80 efficiency criteria with E1 = 80.00 and E2 = 87.16. The effective curriculum consists of five learning units including Unit 1: Using technology media for the elderly, Unit 2: Understanding and digital literacy for the elderly, Unit 3: Creating social media for the elderly, Unit 4: Accessing, efficient use of technology and technology management for the elderly, and Unit 5: Electronic law. The elderly’s capabilities significantly improved at a significance level of 0.05. For curriculum users’ satisfaction, the result showed the highest level of satisfaction with an average score of 4.59. It is concluded that the curriculum is effective and can genuinely enhance the elderly’s learning achievements.

Detection of Bombyx mori as a Protein Source in Feedingstuffs by Real-Time PCR with a Single-Copy Gene Target

The silkworm, Bombyx mori, is reared on a large scale, mainly for silk production. The waste from this silk production, like pupae, is underused. As an edible insect, B. mori is a good source of protein in human food and animal feed. In recent years, European legislation on the use of insects has evolved and a multitude of European companies have initiated the rearing of insects specifically for food and feed applications. Regarding animal feed, Commission Regulations (EU) 2021/1372 and 2021/1925 authorize eight insect species, including silkworm, as processed animal proteins for use in fish, pig, and poultry feed. The incorporation of edible insects into the human diet falls within Regulation (EU) No. 2015/2283 concerning novel foods. Implementation of authentication methods is imperative to ensure the conformity of the products. In the present study, we propose a specific real-time PCR method for the detection of silkworm (B. mori). The developed PCR test amplifies a 98 bp fragment of the cadherin gene. This gene is present in a single-copy per haploid genome, as demonstrated by experimental evidence. The qualitative method was successfully evaluated on the performance criteria of specificity, sensitivity, efficiency, robustness, and transferability. The applicability of the test was assessed on samples of B. mori from industry. Light microscopy and DNA metabarcoding approaches were used as a complement to genomic analysis as a means of providing authentication of the samples.

Parametric Optimization Approach to Evaluate Dynamic Shading Within Double-Skin Insulated Glazed Units for Multi-Criteria Daylighting Performance in Tropics

This research aims to support the choice of an appropriate dynamic louver shading system (DL-SS) within double-skin facade insulated glazed units (DSF-IGUs) as a high-performance integrated window system (DSF-IGUs/DL-SS) that meets both thermal and energy performance via daylight availability under a tropical climate. The research framework has developed a multi-objective optimization method to achieve research objectives via optimizing two different scenarios of the proposed system. The first scenario was optimized for daylighting availability, meanwhile, the second scenario was optimized for energy and thermal performance. For each scenario, the best solutions are selected from respective Pareto fronts according to energy efficiency criteria, thermal comfort via enhancing daylighting availability. Based on the best options resulting from both optimizations, the final step involved comparing the results of all performance indicators in the best cases to select the best solution. Overall, based on the optimizing objectives, the ranking of the best cases varied based on giving priority to the improvement objective in the optimization process. For each scenario, the best solutions are selected from the respective Pareto fronts. Overall, ranking of the best cases varied based on giving priority to the improvement objectives. Optimizing DL-SS within DSF-IGUs while giving priority to improving energy and thermal comfort while maintaining daylighting at acceptable levels is more reasonable. Thus, the DSF-IGUs/DL-SS best-case resulting from the second optimization scenario was overcome all best cases and ranked first in energy and thermal comfort. Compared to the base case, the differences of total Predicted mean vote and percentage of dissatisfied for better thermal comfort achieved were -0.35% and -1.48% with an average decreased by 22.99% and 28.72%, respectively. The differences of total energy and cooling load for better energy performance reduced by -96.84 kwh/m2. and -86.88 kwh with an average decreased by 25.33% and 26.20%, respectively. Meanwhile, the total satisfied of spatial Daylight Autonomy for better daylighting distribution and better daylighting availability of useful daylighting illuminance improvement were improved by -5.54% and +24.76% with an average percentage variation increased by 6.25% and 36.87%, respectively.

Multirobot Assembly Sequence Planning of a Large Space Telescope

As space structures trend toward larger scales and modularization, their on-orbit assembly presents a significant challenge. Assembly sequence planning is crucial in minimizing vibration and enhancing the efficiency of on-orbit construction. This paper explores the multirobot assembly sequence planning algorithm for a large space telescope. A dynamic model is firstly developed to analyze the vibration of segmented mirror pieces and the main satellite during assembly, taking into account the flexibility of connections at interfaces. The dynamic model is able to provide criteria for time efficiency and satellite attitude disturbances. Considering constraints during the assembly process, a modified multiobjective ant colony optimization algorithm capable of planning multirobot assembly sequences is implemented. The simulation results demonstrate that the proposed method not only facilitates parallel planning of multirobot assembly sequences but also leads to a reduction in assembly time and attitude disturbances of the main satellite. The results of assembly sequence planning provide dependable guidance for the subsequent planning levels, such as task planning and trajectory planning, of the on-orbit assembly task for large space telescopes.

ANALISIS POLA DISTRIBUSI CURAH HUJAN LEBAT DOMINAN DI DAERAH ALIRAN SUNGAI (DAS) CITANDUY HULU

Rainfall plays an important role in hydrological and environmental planning. Meteorological conditions affect rainfall through its intensity, amount, and duration. However, heavy rainfall can cause significant damage and loss. Research was conducted in the Upper Citanduy watershed, West Java, using rainfall data from 8 stations over a range of 5–14 years. The study took a heavy rainfall event threshold of ≥ 50 mm in 24 hours. The research aims to analyze the dominant heavy rainfall patterns in the Upper Citandyu watershed. Empirical analysis used the Mononobe Method and Alternating Block Method (ABM), while rainfall distribution was analyzed with Inverse Distance Weighted (IDW) using Geographic Information Systems. The dominant heavy rainfall duration in the Upper Citanduy watershed occurred over 4–6 hours. Rainfall distribution analysis showed a pattern that was not influenced by the elevation of the rainfall station. The analysis results show that the Mononobe Method is closer to the dominant observed heavy rainfall distribution for 4 hours, while ABM is closer to the durations of 5 and 6 hours. The suitability of the distribution pattern was measured using Correlation (r), Root Mean Squared Error (RMSE), and Nash-Sutcliffe Efficiency (NSE) criteria, with Mononobe providing better results than ABM method. This research contributes to the understanding of rainfall patterns that can form the basis for analyzing designed rainfall intensity as a step in flood disaster mitigation in the Upper Citanduy watershed.Keywords: heavy rainfall, rainfall distribution pattern, rainfall intensity, upper Citanduy watershed, geographic information system

Fair and Efficient Ridesharing: A Dynamic Programming-based Relocation Approach

Recommending routes by their probability of having a rider has long been the goal of conventional route recommendation systems. While this maximizes the platform-specific criteria of efficiency, it results in sub-optimal outcomes with the disparity among the income of drivers who work for similar time frames. Pioneer studies on fairness in ridesharing platforms have focused on algorithms that match drivers and riders. However, these studies do not consider the time schedules of different riders sharing a ride in the ridesharing mode. To overcome this shortcoming, we present the first route recommendation system for ridesharing networks that explicitly considers fairness as an evaluation criterion. In particular, we design a routing mechanism that reduces the inequality among drivers and provides them with routes that have a similar probability of finding riders over a period of time. However, while optimizing fairness the efficiency of the platform should not be affected as both of these goals are important for the long-term sustainability of the system. In order to jointly optimize fairness and efficiency we consider repositioning drivers with low income to the areas that have a higher probability of finding riders in future. While applying driver repositioning, we design a future-aware policy and allocate the areas to the drivers considering the destination of requests in the corresponding area. Extensive simulations on real-world datasets of Washington DC and New York demonstrate superior performance by our proposed system in comparison to the existing baselines.

Development of the model and improvement of the method of automated control of steam turbine parameters to minimize the power imbalance in the energy system to increase its efficiency

The object of research is the process of regulating power imbalances due to automated control of steam turbine parameters. The work solves the problem of minimizing power imbalances in the electric power system by developing a model of automated control of steam turbine parameters. This will ensure high-quality regulation of frequency and power, increase the efficiency and stability of the electric power system, and provide a new management method for reliable power supply to consumers. The paper analyzes existing models and methods of power imbalance regulation, develops a dynamic model of automated control of K-300-240 steam turbines, which includes a mechanical-hydraulic system, a steam boiler and a steam superheater. As a result of the study, an improved power regulation method was proposed, which ensures efficient operation of the electric power system. The evaluation of the effectiveness of the regulation of imbalances was carried out on the basis of the proposed criterion of the efficiency of electricity supply and consumption, which is based on the convolution of partial criteria into the general criterion of the efficiency of electricity supply. The following criteria were proposed as partial criteria for electricity supply and consumption: volume criterion, quality criterion, and electricity supply efficiency criterion. The research results indicate the need for a reserve on each steam turbine in the amount of 10 % of its nominal power, which is explained by the assessment of the efficiency of electricity supply among the considered modes of operation of the systems. The presence of a power reserve on each steam turbine in the amount of 10 % of their nominal power ensures the most efficient power supply within the considered modes of operation of the power system, taking into account disturbances and as an imbalance of power generation and power consumption. The obtained research results can be applied in the strategy of primary regulation of power imbalances in the electric power system, thanks to the creation of a power reserve in the amount of 10 % of the nominal power on each steam turbine, and the organization of automated control of steam turbine parameters.

Efficiency criteria and dual techniques for some nonconvex multiple cost minimization models

In this study, we investigate a class of multi-objective variational control problems governed by nonconvex simple integral functionals. Concretely, we establish and prove (necessary and sufficient) efficiency criteria and dual techniques for some nonconvex multiple cost minimization models. To this aim, we extend and use the concept of (Ψ,ω)-invexity to the case of multi-objective variational control problems. Thereafter, by assuming (Ψ,ω)-invexity, (strictly) (Ψ,ω)-pseudoinvexity and/or (Ψ,ω)-quasiinvexity of the involved functionals, we state the sufficient efficiency criteria and associate a dual problem for the considered model.

New algorithm of three-phase equilibrium calculations for CO2-hydrocarbon-water systems

In this century, global warming caused by the accumulation of atmospheric carbon dioxide has become an essential concern. The industry has two main decarbonization options: CO2 capture for permanent storage in geological formations and CO2 utilization for enhancing oil recovery (EOR). Both methods require accurate reservoir simulation to correctly describe the fluids flowing process and design an optimal injection plan. However, existing reservoir simulation practices often neglect the interaction and dissolution of CO2 and hydrocarbon components in water, leading to inaccurate predictions. Neglecting CO2 dissolution in water undermines storage estimation for capture and results in unreliable EOR descriptions. Therefore, to address this, our study focuses on developing a reliable and accurate phase equilibrium calculation package for hydrocarbon-CO2-water three-phase systems, which meets the demanding efficiency and robustness criteria of reservoir simulation. In this paper, we first introduce the methodology of the three-phase equilibrium calculation algorithm, then illustrate the numerical techniques employed to improve computational efficiency and finally demonstrate superior robustness of this algorithm through comprehensive case studies. Our research contributes three key improvements. First, we have increased the reliability of phase behavior descriptions by considering the dissolution of CO2 and hydrocarbon components in water. Second, we have enhanced the robustness of the three-phase equilibrium calculations algorithm, enabling accurate determination of three-phase statuses and fluid behaviors where standard commercial software may fail. Third, our algorithm exhibits notable efficiency improvements, ensuring its suitability for three-phase compositional simulations. The findings of this research provide valuable insights into the accurate modeling of hydrocarbon-CO2-water three-phase systems and offer practical solutions for designing effective CO2 reduction strategies.

Simultaneous optimization of electric production, azo dye, and yeast wastewater treatment in microbial fuel cell: Selection of the most suitable optimal conditions by PROMETHEE

Microbial fuel cell is a clean technology in which waste treatment and energy production continue simultaneously. Process performance depends on the independent variables and their interaction with each other specific to the waste to be treated. In this study, Microbial Fuel Cell (MFC), in which yeast production process wastewater is oxidized in the anolyte, and azo dye is reduced in the catholyte under abiotic conditions, was optimized using the Response Surface Methodology for maximum waste treatment and energy production. The independent variables were wastewater type, electrode array, and amount of sulfate-reducing inhibitor, while the dependent variables were azo dye removal, maximum power density, chemical oxygen demand (COD) removal, and coulomb efficiency. The effect of variables on all responses was determined using Analysis of Variance (ANOVA) and 3-dimensional (3D) graphs. The suitability of the models was tested by verification experiments under the determined optimum conditions (OPT 1, 2 and 3). Optimum experiments were ranked with the PROMETHEE approach according to azo dye removal (mg/L), maximum power density (mW/m2), COD removal (g/L), coulombic efficiency (%), and electrode cost (€/m2) criteria. The preference order of the optimum experiments was determined as OPT 1>OPT 2>OPT 3. With OPT 1, azo dye removal of 16.8 mg/L, maximum power density of 95.34 mW/m2, COD removal of 5.8 g/L and coulombic efficiency of 0.23 % were achieved. With a 1000 Ω external resistor, the maximum power density and coulombic efficiency increased to 147 mW/m2 and 1.5 %, respectively. In addition, the determined optimum experiments were examined using polarization curve and Electrochemical Impedance Spectroscopy.

Exploring the efficiency of employing Fe3O4-MWCNT Nanofluids in a heat sink equipped with circular micro pin-fins

This work investigates the effects of adding different turbulence-inducing elements and varying the concentration of Fe3O4-MWCNT hybrid nanofluid to evaluate the efficiency of a micro pin-fin heat sink. To achieve this objective, a multiphase Lagrangian-Eulerian method that includes gravity, thermophoresis, drag force, Saffman lift, virtual mass, and pressure gradient-induced force to model will employ hybrid nanofluids. The evaluation of heat sink efficiency includes the analysis of quantitative variables like surface Nusselt number, average Nusselt number, and the logarithmic mean temperature difference. Furthermore, a qualitative representation of flow and thermal distributions is illustrated by visualizing flow streamlines, vortex contours, and thermal contours. This topic is addressed in the current work by using the finite volume approach with Ansys Fluent 18.1. Using the multiphase Lagrangian-Eulerian approach, the hydrothermal performance of the Fe3O4-MWCNT hybrid nanofluid in a pin-fin heat sink is investigated. This article's novelty lies in its utilization of four distinct turbulator models, each with unique geometries and widths. These models are positioned within a heat sink with micro fins and are tested in the presence of Fe3O4-MWCNT nanofluids. According to the findings, using the hybrid nanofluid at a concentration of 5 % rather than 1 % causes an average Nusselt number rise of 7.3 %, 9.4 %, and 12.5 % in various heat sink segments. This study's most significant thermal enhancement is associated with case D, which demonstrated a 7 % improvement over the baseline scenario by employing Fe3O4-MWCNT at a concentration of 5 % and a Reynolds number of 2400. It has been demonstrated that hybrid nanofluids have thermal efficiency between 600 and 2400 Reynolds numbers. The thermal efficiency criteria represent the base model, denoted by η = 1. A higher thermal efficiency denotes a more cost-effective design that offers superior heat transmission at a reduced pressure drop. It has been discovered that raising the concentration of hybrid nanofluids improves the micro pin fin heat sink's thermal performance by increasing the heat transfer coefficient.

Выбор аналитической модели и количественных показателей для геоинформационного анализа устойчивого развития территориальных образований

Currently, there are no generally accepted algorithms for assessing, analyzing and forecasting the sustainable development of administrative-territorial units. The authors introduce the definition of this term, which implies the successful functioning of a human community over time carrying out economic activities without threats to its environment. Also, an analytical model for representation of its regional integrated indicator in the form of a vector with differential components, which characterize economic growth, environmental and social metrics, in a three-dimensional affine space, is proposed. Furthermore, we present a multiplicative criterion for assessing partial criteria of sustainable development efficiency and the basic expression for its parameters computation based on the set of economic, environmental and social ones, including such as the availability and quality of natural resources, regional labour resources, eco-factors, etc. The proposed vector model is based on the geoinformation approach and can be deployed within the framework of GIS of sustainable development for geo-analysis, modeling and mapping of natural resource potential and ecological state of intensively advancing territories, considering the dynamics of this process. Important properties of the geoinformation approach to assessing territorial entities’ forward growth, spatial and semantic scalability, are noted. In addition, the functional requirements and preliminary architecture of the core, modules, clients and layers of the related thematic geographic information system for the management, planning and forecasting the said indicator within the framework of digital economy are described

Construction of Fatigue Criteria Through Positive‐Unlabeled Learning

AbstractThe reliability of vehicles is a significant issue for automotive manufacturers, with mechanical fatigue representing a pivotal aspect of the design process. To accelerate the development of novel mechanical components, automotive manufacturers are increasingly employing numerical simulations with the objective of markedly reducing the number of prototype validation tests. This requires the utilization of efficient fatigue criteria capable of accurately identifying critical zones in numerical models. However, the current fatigue criteria frequently fail to demonstrate a satisfactory correlation with the results obtained from fatigue test rigs. In response, this paper proposes a probabilistic Dang Van criterion that accounts for variability in fatigue results within a multiaxial context. Additionally, a fatigue database comprising numerical results and test reports on automotive chassis components is introduced. A novel approach utilizing positive‐unlabeled learning is developed to enhance the predictive accuracy of the fatigue criterion. Its effectiveness is demonstrated through application to the fatigue database.

Comparing the success and failure of the Murray–Darling Basin Plan's water recovery programs

AbstractThe Murray–Darling Basin (MDB) Plan is held up by some as an exemplar for world‐leading water policy, whilst others have called it a failure. Total proposed recovery was to return 3200 GL of consumptive (e.g. namely irrigation) water use to non‐consumptive (e.g. environmental) use in the MDB, making it one of the largest planned reallocations of water resources in the world. As of June 2023, over AUD$13 billion was committed financially from the Australian government to Basin water reform, with AUD$7.7 billion spent to date on water recovery programs. The implementation of the Plan has been mired in controversy, and it missed its first water recovery targets that had been set for 2024, requiring substantial legislation amendments. This study provides a qualitative policy overview comparison of the success and failure of the two main water recovery programs implemented—buyback of water entitlements from willing sellers and subsidising irrigation infrastructure (on and off‐farm) projects. It concludes that contrary to the popular view held by many, the buyback water recovery program has been a success—achieving the majority of the water recovered to date, at the least cost, with the least negative externalities—in comparison to infrastructure programs.Points for practitioners Assessing success and failure of MDB water recovery programs requires establishing effectiveness, efficiency and equity criteria. Greater work on the benefits of water reallocation downstream and cultural water is needed. A comparison of MDB buyback water recovery programs with irrigation infrastructure programs found higher net benefits for buyback programs. Use first‐best policy to address each water policy objective, not one policy aimed at addressing multi‐objectives. Overall, the Plan.s overall success is still to be determined, given the difficulty in judging environmental outcome success that is intrinsically linked with other external factors.

An examination of direct and indirect taxation in OECD countries and the case of Greece

This paper attempts to analyze and interpret the principles of direct and indirect taxation. Initially, a theoretical approach to the general concepts and principles governing tax law is presented. It is followed by a presentation of the Greek tax and financial system. The key points demonstrating the harmonization of tax legislation, in accordance with the OECD (Organization for Economic Cooperation and Development) guidelines so far are highlighted. Any future reform of the Greek national tax system should incorporate the fundamental principles of national tax policy. Additionally, it must be in line with OECD principles and guidelines. The further implementation of the Organization's recommendations will shift the balance between direct and indirect taxation, leading to strengthening the first and reducing the second. Over the last decades, the ratio of direct to indirect taxes has been on the increase, particularly in developed countries. The main reason is that direct taxation is socially just and effective. Direct taxation is attributed by the liable person, while indirect taxation is transferred according to the ability of each person to react to the relevant market. The OECD supports, for member countries, the strengthening of direct taxation, which takes into account income and other social criteria and satisfies both the criterion of efficiency and the criterion of fair distribution of economic burdens. On the contrary, indirect taxation is reduced to inversely progressive taxation in terms of the income of consumers and is not consistent with the OECD principles of socially just and effective taxation in economically developed countries. The taxation of the citizens in general follows the principle of the citizens contributing to the public burdens according to their powers, for there is nothing more unjust than to treat unequal men as equals. From this proportional treatment of the taxing units, the constitutional principle of equality is also satisfied by reflection.

Evaluation of space efficiency criteria in high-rise buildings based on functions: a case study of Türkiye

ABSTRACT High-rise buildings have become a significant solution to address the challenges posed by the rapid growth of urban populations and space limitations in cities. Efficient planning and design of these buildings, aiming to achieve more productivity, can be realized through ensuring space efficiency. This research compares architectural and structural design criteria affecting space efficiency in high-rises based on their functions, aiming to assess the degree of correlation among these criteria, space efficiency, and their interrelations. Currently, no studies examine the differences or similarities in space efficiency of high-rise buildings based on their functions. Additionally, selecting buildings from the same region as samples is a unique aspect of this study. Employing a case study method, the analysis encompasses 42 high-rises in Türkiye, ranging from 100 m to 300 m, and utilizes correlation analysis methods to examine the data. The comprehensive review of space efficiency in high-rises, based on their functions, yielded the following results: (i) Space efficiency ranged from 82.7% to 65.2% in high-rise case studies with different functions, with an average of 73.2%. (ii) A significant majority (83%) of the buildings followed orthogonal designs. (iii) Central core floor planning emerged as the preferred approach. (iv) Increasing elevator density reduced space efficiency. (v) Office buildings favored reinforced concrete frame systems, while residential buildings commonly used reinforced concrete shear wall systems. (vi) As building height increased, elevator and core areas expanded. These findings provide guidance for future high-rise building design and planning.

ANALYSIS OF THE ENERGY EFFICIENCY OF TECHNICAL SOLUTIONS OF THE HEAT-DRIVEN SHIP EJECTOR REFRIGERATION MACHINE FOR OBTAINING SUB-ZERO TEMPERATURES

Marine refrigeration machines are responsible for large amounts of electricity consumption, as well as direct emissions of high global warming potential (GWP) refrigerants, so they need to be gradually upgraded. The possibility of using a ship ejector refrigeration machine with two-stage compression, consuming waste heat, as well as a cascade compression-ejector refrigeration machine to obtain the temperatures of minus 28–27 °C was analyzed. It was shown that the traditional indicator of the efficiency of heat-driven refrigeration machines COPtherm ot be recommended for the selection of energy-efficient modes of operation of ejector refrigeration machines that consume waste heat. As a criterion for the energy efficiency of ejector refrigeration machines that consume waste heat, it is proposed to analyze COPmechTot, which takes into account the electric power of pumps, fans, as well as units that provide “feeding” the refrigeration machine with waste heat. A two-stage ejector refrigeration machine that consumes waste heat with a temperature of 95–45 °C and is intended for the operation of a ship ice generator (boiling temperature — 28 °C) loses to a traditional vapor compression refrigeration machine in terms of energy consumption: COPmechTot = 1.266 vs. COPmechTot = 1.52. A cascade vapor compression ejector refrigeration machine that consumes waste heat with a temperature of 85–95 °C and is designed to provide refrigeration (boiling temperature — 27 °C) of ship provision chambers is more attractive than a traditional vapor compression one: COPmechTot = 2.37 vs. COPmechTot = 1.82. An alternative technical solution for the production of sub-zero temperatures on ships, which the authors plan to consider in further research, is a refrigeration machine with two-stage compression. It uses a compressor in the first stage and an ejector in the second stage. Bibl. 26, Fig. 7, Tab. 1.

Evaluation of heat transfer enhancement effect at the hot/cold end of a Stirling engine using performance improvement factor

The driving force of a Stirling engine comes from the heating expansion and cooling compression of working medium. The enhancement of heat transfer capacity of the hot/cold end is the key to improve the Stirling engine performance, while how to objectively evaluate the heat transfer enhancement effect is a precondition. Herein, a polytropic model of a Stirling engine thermal cycle process was firstly established. A method for evaluating the heat transfer enhancement performance under oscillating flow was proposed based on the efficiency and power improvement of a Stirling engine. This method was further used to evaluate the heat transfer enhancement effect of a novel four-leaf helical heating tube under oscillating flow, the efficiency and power improvement factor of which was reached 13.5 % and 6.1 %, respectively. The results show that the efficiency and power improvement evaluation criterion was more comprehensive and intuitive in evaluating the heat transfer enhancement performance under oscillating flow compared with the conventional evaluation indictor like performance evaluation criterion and equivalent tube length and tube number criterion.

Developing some models to predict the uniaxial compressive strength of various sedimentary rocks (Case studies: Large dam site and mine in Southeast China)

Direct determination of uniaxial compressive strength (UCS) is time-consuming, expensive, and challenging. Therefore, this study aims to indirectly predict UCS using statistical and machine learning methods. First, laboratory measurements were conducted to determine carbonate percentage, water absorption percentage, moisture content, porosity percentage, P-wave velocity, and UCS of sandstone, dolomite, dolomitic limestone, marl limestone, and limestone samples. Subsequently, various models were established to predict UCS using multivariate linear regression (MVLR), random forest regression (RFR), Gaussian process regression (GPR) based on squared exponential kernel function, and adaptive neuro-fuzzy inference system (ANFIS). The influence of Jurassic limestone texture on physical and mechanical properties in stable and unstable slopes in the Three Gorges Dam site and reservoir (TGDSR) showed that the percentage of mudstone texture in unstable slopes is higher than in stable slopes. The UCS, density, compressional wave velocity, and percentage of carbonate in unstable slopes is less than stable slopes. The results indicated that the average measured UCS is 60.60 MPa. Moreover, the average predicted UCS based on the three intelligent methods was 60.55 MPa. The percentage difference between the measured and predicted UCS was −0.09 %, demonstrating that the average error of the three employed methods is less than one percent, highlighting the high accuracy of these methods in estimating rock UCS. Notably, based on error level, Taylor diagram, Wilmot agreement index (WAI), A10 and A20 indices, Nash-Sutcliffe efficiency (NSE), and PM (performance metric) criteria the RFR exhibited superior precision (R2=99 %, and RMSE= 0.06 MPa) compared to the other used methods. The Kruskal-Wallis test (KWT) results showed that there is no significant difference between the measured and predicted values.

An Investigation on unstable flow during hot deformation of Inconel X750 superalloy using 3D processing map and shear band formation criterion

In this study, deformation efficiency and instability criteria were employed to delineate the unstable flow regions for Inconel X750 superalloy through high temperature deformation. High temperature stress–strain data attained from isothermal hot compression experiments in the temperature range of 950-1150 °C and strain rates between 0.0001 and 1s⁻¹ to identify safe and un-safe deformation domains in terms of an integrated 3D processing maps. These domains were validated through detailed microstructure observation and material tendency to shear band formation in terms of the competition between work hardening and strain rate sensitivity i.e. flow localization parameter. The superimposed effect of microstructure features like dynamic precipitation, dynamic recovery (DRV), and dynamic recrystallization (DRX) with destructive shear banding were responsible for controlling the material behaviour. Based on the TEM images, it was observed that material revealed stable flow at lower strain rates while adiabatic shear band and flow localization occurred at higher strain rates due to activation of slip systems and cell formation.