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This paper is concerned with optimal directions in the directional distance function in data envelopment analysis. It is shown that the vector pointing in the direction that minimizes the Euclidean distance between the input–output vector ( X o , Y o ) and the efficient frontier, the input isoquant reflecting output Y o , or the output isoquant reflecting input X o is optimal, because the corresponding vector of virtual multipliers defines the relative prices that maximize profit, cost, or revenue efficiency. The associated efficiency indicator is a value measure of technical efficiency in difference form with the Euclidean distance between ( X o , Y o ) and the efficient frontier, the Y o input isoquant, or the X o output isoquant as an equivalent directional distance quantity indicator. A linear combinatorial optimization program for computing the relevant value indicators of technical efficiency in multiplier space or the equivalent quantity indicators in terms of the relevant Euclidean distances is developed. A nonlinear and nonconvex optimization model for an estimation of the relevant value indicator of efficiency in multiplier space is also developed. Preliminary computational results are reported.

A new pumpless liquid cooling system for a single-stage two-cylinder reciprocating compressor has been developed from the analysis of work processes and cooling systems of reciprocating compressors, where one piston compresses and moves gas and coolant in the cooling system. The intensification of the coolant movement increases in the machine, which can reduce the temperature of the cylinder–piston group and increase the indicator efficiency and the compressor feed rate. A mathematical model of working processes in a reciprocating compressor and its cooling system has been developed on the basic fundamental laws of conservation of energy, mass and motion. A prototype was developed and tested to obtain new knowledge about the processes in the machine and confirm the assumptions made while developing the mathematical model. After a series of experiments, the influence of cooling on the working processes in a reciprocating compressor, the technical work carried out in each working process, the energy and consumption characteristics of a reciprocating compressor with a developed cooling system were established. There was a validation performed of the developed mathematical model of work processes in the machine and the assumptions made. According to the developed mathematical model of work processes, a numerical experiment was carried out, which established: the coolant flow rate decreases with an increase in discharge pressure and increases with an increase in the crankshaft speed when the discharge pressure changes from 0.4 MPa to 0.8 MPa, a decrease in the indicator isothermal efficiency due to the leakage and non-isothermal nature of the compression process, as well as a decrease in the return work in the process of reverse expansion, leading to a decrease in the indicator isothermal efficiency of more than 15%; due to the equalization of pressures in the gas cavities with an increase in discharge pressure, the coolant consumption is reduced by (15 ± 17)%; with an increase in the angular speed of the crankshaft from 800 rpm to 1500 rpm, the coolant flow rate increases by more than 2.5 times, this increase in coolant flow rate is due to an increase in hydraulic resistance due to an increase in gas velocity; in the range from 1000 to 1200 rpm, a maximum of the indicator isothermal efficiency and compressor feed rate is observed; maximum indicator isothermal efficiency and the supply ratio is observed at a coolant flow rate in the range from 800 mL/min to 900 mL/min.

Blended teaching combines the advantages of online teaching and offline teaching, which breaks the limitation of time and space to a certain extent and is of great significance to helping learners improve their learning efficiency and teachers’ teaching level and quality. This paper firstly designs a blended teaching model for the background of Internet+ education and improves the functional design of each part of the model. Secondly, the extreme gradient prediction model of students’ academic level is proposed for the blended model, and a strong learner is formed by integrating multiple weak learners to correct the misclassification. Finally, the blended model of instruction is evaluated and analyzed. The model achieves an accurate prediction accuracy of 65% for MEDIUM students and 75% for PERFECT students, with an average prediction accuracy of 58.4%, which is more than 50%, and can predict students’ academic level situations more accurately. The functional indicators all scored 74.4, the efficiency indicators all scored 71.35, and the usability of the platform exceeded 70. The Internet+education platform’s professional-type English, the online and offline hybrid teaching model, can effectively improve learners’ learning efficiency, as well as improve teachers’ teaching standards and quality.

The article talks about the newly-conceived HGN model based on ratio indicators. The main characteristic of the model is a synthetic indicator based on “refining” chosen financial efficiency indicators by separating out impacts measured by using chosen efficiency decreasing indicators. We identify and present a way to determine the minimum limits of the synthetic indicator characterizing the performance of a non-financial enterprise. We apply both the classical and tolerance approach to sensitivity analysis in a linear optimization model. We demonstrate the performance measurement possibilities provided by the gradual improvement of the HGN model by designing two versions of the model.

Background The association of advanced digital image correlation (DIC) and numerical simulation has been widely used for inverse parameter identification. Objective It is attractive to develop an accurate DIC method sharing the common features with numerical simulation, which can lead to better synergy between experiments and simulations. Methods A new meshfree digital image correlation (MF-DIC) using element free Galerkin method (EFGM) is proposed for deformation measurement. The EFGM is a classical meshfree method in numerical studies, and it is directly used to construct the shape function in MF-DIC from a set of scattered nodes for image matching. The MF-DIC is principally different from the classical local DIC and global DIC since it does not rely on the concept of a subset or an element. Results In MF-DIC, the C 1 -continuous displacement for every point is constructed based on a group of scattered nodes in a small support domain surrounding it. The continuous strain map can then be directly derived from the displacement, instead of using an additional smoothing technique as required in classical local DIC or post-processing used in global DIC. A performance assessment based on the Metrological Efficiency Indicator (MEI), as defined in DIC Challenge 2.0, shows that the proposed MF-DIC yields an excellent balance between spatial resolution and measurement resolution for both displacement and strain measurements. Conclusions Given that the proposed MF-DIC shares common features with the classical meshfree method in computational mechanics, it paves the way for an enhanced synergy between experiments and simulations required for robust inverse parameter identification methods.

When assessing energy efficiency, most studies have frequently ignored environmental aspects even though the concept has been widely used in the past. This study evaluates the energy efficiency and environmental performance of South Asia by using DEA (data envelopment analysis) like mathematical composite indicator. We construct a comprehensive set of indicators, including an energy self-sufficiency ratio, energy production over consumption ratio, energy imports, diversification index of energy imports, energy reserve ratio, GDP productivity, energy intensity, per capita energy consumption index, carbon emission index, carbon emission index per unit of energy consumption and share of renewable energy in order to develop an energy efficiency and environmental performance index. Unlike other studies, this study first examines each indicator and then estimates a combined score for each country. The results reveal that Bhutan as a more secure country and Pakistan showed a decreasing trend, while Sri Lanka and India performed satisfactorily. Remarkably, Bangladesh, Nepal and Afghanistan showed a decreasing trend. This study proposes a policy that increases the cross-border trade of renewable energy for long term energy efficiency and environmental performance.

Green innovation has now become an important component of high-quality development, but China’s provinces still face imbalances in green innovation development. Clarifying the current state of development and the causes of the imbalance in each province is urgently necessary. But only a single or overall indicator cannot well reflect the structural differences within each province. We used the multi-way efficiency analysis (MEA) method to analyze the overall and structural efficiency of green innovation in each province of China, thus overcoming the shortcomings of comprehensive indicators. In addition, based on the decomposition of regional differences, policy factors resulting in heterogeneity among provinces are analyzed using Geodetector. The research results reveal the diversity of green innovation systems, the severe symmetry in resource utilization, and the internal and external sources of regional differences. We categorize the provinces into four development models by combining the internal structural characteristics of green innovation efficiency, as a way to propose suitable green innovation policies for each province, to take into account, the different development environments of the provinces assessed. Our research has significant implications for effectively improving green innovation efficiency and guides the formulation of more precise policies.

The assessment of solid waste management systems is vital for continued improvement in the efficiency of waste management systems (WMSs). Many studies have aimed to develop metrics that examine policy and system effectiveness, but there appears to be a lack of simple and comparable metrics to evaluate the WMS efficiency. This study introduces a set of novel waste diversion indicators, including a jurisdictionally comparable index known as diversion size indicator (DSI), and employs them to analyze WMSs in Canada. DSI increased in only a single province Nova Scotia during the 14-year study period. The DSI variability was largest for all Prairie Provinces, indicating that large efficiency changes in these province’s WMSs over the study period. Combining all proposed metrics into a single rank showed that Saskatchewan outperformed all other Canadian jurisdictions, balancing diversion rate goals well with cost efficiency. Findings indicate that Alberta and Ontario rank very low in diversion efficiency and tonnage hauled efficiency. Also, Nova Scotia, the DSI leader, ranks lowest in terms of costs per tonne handled. Data availability remains a large barrier to a complete evaluation of WMSs. Nonetheless, the proposed original metrics create a framework for creating comparable and easy to use metrics for waste management efficiency.

Açaí seed ash (ASA) is a waste product from processing the açaí fruit and burning the seeds for cogeneration purposes. The present study evaluated the use of ASA from the Brazilian Amazon as partial Portland cement replacement in self-leveling mortars (SLM) for social-interest buildings. The fresh and hardened state properties of mortars were accessed with 5% and 10% ASA content, and a life cycle assessment was performed to evaluate the greenhouse gas (GHG) emissions. The maximum transport distance to enable ASA as a building material was determined by a sensitivity analysis, and specific carbon-efficiency indicators for SLM were proposed and validated. The results showed that using up to 10% ASA as cement replacement was technically and environmentally feasible since the mechanical performance was maintained and GHG emissions decreased up to 8%. The sensitivity analysis revealed that transport efficiency is crucial for ASA applications far from its production area; therefore, it should be evaluated as a regional building material. The work brings an important contribution to regional sustainable development by assessing the characteristics of a residual material and proposing the reuse of waste, reducing GHG emissions from the cement industry, and stimulating the circular bioeconomy in the Brazilian Amazon region.

Three waste management system (WMS) efficiency indicators are adopted to systematically assess WMS efficiency in Canada from 1998 to 2016. The study objectives are to examine the temporal changes in waste diversion activities and rank the performance of the jurisdictions using a qualitative analytical framework. Increasing Waste Management Output Index (WMOI) trends were identified in all jurisdictions, and more government subsidiaries and incentive packages are recommended. With the exception of Nova Scotia, statistically significant decreasing diversion gross domestic product (DGDP) ratio trends are observed. It appears that the increases in GDP from Sector 562 were not contributing to waste diversion. On average, Canada spent about $225/tonne of waste handled during the study period. Current spending per tonne handled (CuPT) trends are decreasing, with S ranging from + 5.15 to + 7.67. It appears that WMSs in Saskatchewan and Alberta are more efficient. The results suggest that the use of diversion rate alone to evaluate WMS may be misleading. The findings help the waste community to better understand the trade-offs between various waste management alternatives. The proposed qualitative framework utilizing comparative rankings is applicable elsewhere and can be a useful decision support tool for policy-makers.