With the serious impact of fossil fuels on the environment and the rapid development of the global economy, the development of clean and usable energy storage devices has become one of the most ...important themes of sustainable development in the world today. Supercapacitors are a new type of green energy storage device, with high power density, long cycle life, wide temperature range, and both economic and environmental advantages. In many industries, they have enormous application prospects. Electrode materials are an important factor affecting the performance of supercapacitors. MnO2‐based materials are widely investigated for supercapacitors because of their high theoretical capacitance, good chemical stability, low cost, and environmental friendliness. To achieve high specific capacitance and high rate capability, the current best solution is to use MnO2 and carbon composite materials. Herein, MnO2–carbon composite as supercapacitor electrode materials is reviewed including the synthesis method and research status in recent years. Finally, the challenges and future development directions of an MnO2–carbon based supercapacitor are summarized.
In this paper, the mechanism of MnO2‐based supercapacitors is summarized, and the synthesis method and research status of MnO2‐carbon based supercapacitor electrode materials in recent years are reviewed. Finally, the challenges and future development directions of MnO2‐carbon based supercapacitors are discussed.
In this paper, we first preprocessed the user’s shopping behavior data, set the prediction goal, constructed the features of the user’s online purchasing behavior prediction model, and classified and ...selected the constructed features based on the SVM-RFE algorithm. Then, on the basis of the fuzzy neural network algorithm of fuzzy theory, the network purchasing behavior prediction model was constructed by combining the assessment indexes of the prediction model results as well as the 5-fold cross-validation method. Finally, the evaluation results of the prediction model are examined and compared with common prediction algorithms to confirm the performance of the algorithm in this paper. The results show that the average relative error of model training can reach 0.013, and the absolute error with the actual value ranges between 0.01, 0.06. On the same test set, the F1 value of the prediction model in this paper is between 0.88, 0.91, and the F1 value of the algorithm on each test set has a small difference of only 0.03, and the F1 value of the other prediction models has a maximum difference of 0.09. The prediction model constructed in this paper has a good prediction effect and robustness.
Through reviewing the literature about green technology innovation and its impact factors, the evaluation indicator system is constructed which includes positive factors and barrier factors. The ...evaluation model is developed by the entropy weighted TOPSIS method, the entropy method is applied in the weighting process of evaluation indicator system, The final points of the evaluation objects are gotten by the TOPSIS method. 6 industries are selected to be the research objects on which the empirical analysis is made. Finally, the dynamic management strategies are implemented to promote the ecological-economic efficiency of green technology innovation according to the evaluation results.
Display omitted
•The evaluation indicator system is constructed which includes positive factors and barrier factors.•The evaluation model is developed by the entropy weighted TOPSIS method.•Six industries are selected to be the research objects on which the empirical analysis is made.•The dynamic management strategies are implemented to promote ecological-economic efficiency.
In order to evaluate the impact of green technology innovation on ecological-economic efficiency of strategic emerging industries, the evaluation model is developed by the entropy weighted TOPSIS method. Through analyzing the impact factors of green technology innovation, the evaluation indicators system is constructed including positive factors and obstacles factors. The evaluation process is proposed, and six kinds of industry are selected to be the research objects on which the empirical analysis is made, the results show that the highest is the home audio-visual equipment manufacturers S6(E) whose weight is 0.7940 and the lowest is the electronic computer manufacturers S2(E) whose weight is 0.1938, finally, the countermeasures are proposed. The findings can avoid the subjectivity of human factors on the empowerment and solve the limitations of sample size and data distribution, and can help researchers precisely find the deficiency based on evaluation results.
Green innovation is of great significance to promote high-quality growth of the national economy and reduce the load on the ecological environment. This study constructs a two-stage SBM-DEA model ...including energy and undesirable output to measure green innovation efficiency. Tobit model is used to analyze the impact of input variables and influencing factors. The main results are as follows: achievement transformation, technology development and green innovation efficiency in each region all show a trend of fluctuating growth, and green innovation efficiency in the eastern region has always been in a leading position. The total current volumes of R&D personnel and government support strength have a positive relationship and the intensity of R&D funding and environmental protection investment has a negative relationship with the technology development. The number of patent applications and the openness degree to the outside world are positively related to the achievement transformation, and the investment of new products and energy is negatively related to the achievement transformation. Through the comparative analysis of the innovation efficiency differences among different regions, the paper analyzes the main influencing factors, and puts forward countermeasures and suggestions to provide certain theoretical reference for the sustainable and healthy development of China's various regions.
•Constructing a two-stage SBM-DEA model including energy and undesirable output.•Many ample rooms still existed for improving the efficiency in the divided two stages.•A matrix diagram was gotten, and four types were classified based on the differences of regional innovation efficiency.•The overall evolution trends in all regions exhibited the volatile growth tendencies.•Putting forward corresponding policy implications.
•The sectional coefficient ζ was introduced to describe the tunnel cross section.•The dimensionless backlayering length and critical velocity were proposed.•Two hundred fifty simulations based on ...nine typical tunnels were carried by FDS.•Forty-five small-scale model experiments were carried out in a 1/10 scale model tunnel.•The slopes of the tunnels in simulations and tests were from −3% to 3%.
The critical velocity and the backlayering length of smoke in tunnel fires are the two most important parameters in longitudinal ventilation design. This paper deduced the dimensionless expression of backlayering length and critical velocity of smoke in tunnel fires using the dimensional analysis method. The sectional coefficient ζ (ζ = A/H2) was introduced to describe the geometrical characteristic of the tunnel section, and the characteristic hydraulic diameter of the tunnel H¯ replaced the tunnel height H. Then, CFD simulations were conducted in nine tunnels with different cross sectional shapes using the proprietary software Fire Dynamic Simulator (FDS), version 5.5. With the FDS simulations, prediction models for backlayering length and critical velocity modified by the sectional coefficient ζ and the tunnel slope were proposed. Meanwhile, complementary experiments were carried out in a 1/10 scale tunnel in order to provide a verification. The experimental results show a good agreement with the numerical simulations. Moreover, the prediction models for critical velocity on different slopes were compared with the prediction models proposed by others.
A series of easily prepared Lewis basic ionic liquids were developed for cyclic carbonate synthesis from epoxide and carbon dioxide at low pressure without utilization of any organic solvents or ...additives. Notably, quantitative yields together with excellent selectivity were attained when 1,8‐diazabicyclo5.4.0undec‐7‐enium chloride (HDBUCl) was used as a catalyst. Furthermore, the catalyst could be recycled over five times without appreciable loss of catalytic activity. The effects of the catalyst structure and various reaction parameters on the catalytic performance were investigated in detail. This protocol was found to be applicable to a variety of epoxides producing the corresponding cyclic carbonates in high yields and selectivity. Therefore, this solvent‐free process thus represents an environmentally friendly example for the catalytic conversion of carbon dioxide into value‐added chemicals by employing Lewis basic ionic liquids as catalyst. A possible catalytic cycle for the hydrogen bond‐assisted ring‐opening of epoxide and activation of carbon dioxide induced by the nucleophilic tertiary nitrogen of the ionic liquid was also proposed.
After collection of geographical remote sensing imaging data, GIS essential data, economic statistical data and hydro meteorological data in Anhui Province and then standardization of them, the paper ...involves evaluation research on the ecological environmental quality of Anhui Province using the ecological footprint analysis approach, and also involves measuring of the ecological footprint, ecological environmental carrying capacity, and ecological deficit and surplus, and analyzing and evaluating the measurement results based on the data regarding ecological environment, society, economy, and population in Anhui Province.
•Computational formula for ecological environmental quality.•Collection of evaluation data, and standardized them.•Calculation of ecological footprint in Anhui Province.•Computation of ecological environmental carrying capacity in Anhui Province.•Computation of ecological deficit and surplus in Anhui Province.
Under the dual pressures of the socio-economic development and the increase in population density, the ecological environmental quality issues in Anhui Province have become increasingly prominent, which seriously handicap the sustainable development of regional economy, and it is more important to evaluate ecological environmental quality. By using the data of ecological environment, society, economy and population in Anhui Province, this paper measures ecological footprint, ecological environmental carrying capacity and ecological deficit and surplus in Anhui Province based on ecological footprint. The results show that ecological environmental quality in Anhui Province is not in the best state of the coordinated development, and the relationship between the supply and the demand of per ecological footprint almost is not in balance.
Debris flows are abrupt geological hazards frequently resulting in destructive disasters in mountain areas. Thus, analysis of the acceptable risk of debris-flow disasters should be attentively ...considered, whereas the crucial problem of the acceptable disaster risk is how to know what the risk levels of debris-flow disasters are acceptable for the public. Thence, the questionnaire investigation of the acceptable risk preferences for different populations in various regions can be such a solution. The acceptable disaster risks are not only taking into account people's acceptance, but also related to government's disaster-reduction strategy and also referred to expert’s professional evaluation. Therefore, the establishment of guidelines and criterions for the acceptable risks of debris-flow disasters need all participations from multiple populations and different regions. In this survey, three-category populations including ordinary people, experts/scholars and administrators across China joined the questionnaire investigation. Five indicators (disaster-affected toll, death toll, death rate, personal direct economic loss, and total direct economic loss) were used to describe the acceptable risks of debris-flow disasters. Incorporated with frequency analysis, this work has explained the demographic characteristics for the acceptable risk preferences. The results indicate that ordinary people have relatively low acceptable risks, experts/scholars have slightly high acceptable risks and administrators have acceptable risks between both of them. Educational level, occupation, and income were the dominatingly demographic factors for the interpretations of the acceptable risk preferences.
PDF
