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A simple relationship is proposed to construct constant-damage energy factor (γDI) spectra of single-degree-of-freedom (SDOF) oscillators with different levels of damage, expressed by the Park-Ang damage index. γDI is computed for SDOF oscillators with four hysteretic models when subjected to 80 pulse-like ground motions. The statistical dependence of γDI on initial period, damage index, postyield stiffness ratio, and ultimate ductility factor is investigated. In comparison with the non-pulse-type ground motions, the near-fault pulse-type ground motions can significantly increase the γDI of structures, and the magnitude of the increase can reach about 200%. Conservative estimates of mean γDI of SDOF oscillators are proposed taking into account the combined effect of period, damage level, and ultimate ductility factor. [ABSTRACT FROM AUTHOR]

The important indications for assessing CCHP (combined cooling, heating and power) systems are their supply-demand matching characteristics between the user demand side and the energy supply side. These characteristics are primarily influenced by different building types and operating strategies. In view of the energy redundancy of the following electric load (FEL) and following thermal load (FTL) operation strategies and the energy deficiency of the following hybrid electric-heating load (FHL) operation strategy, this paper proposes an improved following balanced heat-electrical load (IFBL) operation strategy based on the following balanced heat-electrical load (FBL) operation strategy. Based on the energy utilization rate as the objective function, this paper optimizes the installed capacity of CCHP systems in different buildings and proposes an energy factor for evaluating the supply-demand matching characteristics of the system. The results show that the energy utilization rate and energy factor of the system under IFBL are optimal relative to the other operation strategies. Secondly, the hotel building has the highest energy utilization rate and the lowest energy factor; on the contrary, the office building has the lowest energy utilization rate and the highest energy factor. Finally, the analysis of supply-demand matching for different building types under multiple operating strategies shows that the hospital and hotel systems exhibit optimal supply-demand matching performance under the IFBL strategy, with values of 0.945 and 0.938, respectively; on the contrary, the office system has an optimal supply-demand matching of 0.935 under the FEL strategy. Under the FTL strategy, the systems of all three buildings exhibit poor matching performance. [ABSTRACT FROM AUTHOR]

The rational allocation of industrial factors in resource-based cities is a necessary condition for promoting high-quality economic development. To systematically measure the mismatch of industrial factors, this study integrates the production function model and accounting framework of Aoki (2012). The capital, labor, and energy factors are integrated into the overall measurement framework, and the factor mismatch calculation model is innovatively constructed at the city level. To effectively reflect the factor mismatch of different cities, the relative distortion coefficient of factor price is introduced to establish the relationship between the distortion of factor-use cost and effectiveness of resource allocation. The degree and direction of factor mismatch are effectively measured. This study takes China's resource-based cities as the research object. To avoid the impact of the COVID-19 pandemic, data on 114 resource-based cities in China from 2003 to 2018 are selected, and 164 non-resource-based cities are used as the control group to evaluate the factors affecting the transformation of such cities. Regarding the diversity of resource-based cities in China, this study compares the characteristics of factor misallocation in these cities for different growth stages, geographical regions, and dominant resources. Finally, this study finds that on average, the cities' degree of energy misallocation is the most serious, and the degree of labor misallocation ranks second. The degree of capital misallocation ranks the lowest, but the misallocation of various factors is very different in different situations. Therefore, different types of cities should make detailed policy adjustments in various transformation directions according to the calculation results.

The influences of applied pressure on the structure, mechanics, dislocation, and electronics properties of an FeTi hydrogen storage alloy are theoretically investigated via first-principles calculations. The lattice parameter ratio, elastic constant, Young's modulus, bulk modulus, shear modulus, ductile/brittle, Poisson's ratio, anisotropy, Cauchy pressure, yield strength, Vickers hardness and energy factor are discussed versus applied pressure. The results show that the FeTi alloy exhibits good mechanical stability under applied pressure between 0 and 50 GPa, and the mechanical properties are significantly improved under applied pressure, like the resistances to elastic, bulk, and shear deformations, the material ductility and metallicity, as well as Vickers hardness and yield strength. Moreover, the electronic structures reveal that the FeTi alloy has metallic properties and the structural stability of the FeTi hydrogen storage alloy is enhanced at high pressure. This work provides significant value for high-pressure applications of FeTi alloys in hydrogen storage and supply fields. [ABSTRACT FROM AUTHOR]

Effects of Al and La elements on mechanical properties of CoNiFe0.6Cr0.6 high-entropy alloys (HEAs) with face-centered cubic (FCC) structure were investigated by first-principles calculations. The variation curves of relevant physical parameters, including lattice constants, formation enthalpy, elastic constants, elastic modulus, Poisson's ratio, Pugh's ratio, Cauchy pressure, anisotropy factors, Vickers hardness, yield strength, and energy factor, as a function of Al and La concentration were discussed in detail. Results show that the resistances to bulk, elastic, and shear deformation decrease with the increase of Al and La concentration. The addition of Al and La can improve the plasticity and ductility of HEAs. Meanwhile, with the increase of Al and La concentration, the metallic characteristic of atomic bonding strengthens and the anisotropy of materials increases. Moreover, the energy factor indicates that the addition of Al and La could promote dislocation nucleation. This study provides a guideline for further research on non-equiatomic CrFeCoNi series HEAs with designed mechanical properties.

Important for promoting the integrated protection and systematic management of mountains, rivers, forests, farmlands, lakes, grasslands, and sandy areas, ecological networks form the backbone of the regional ecological security pattern. An improved morphological spatial pattern analysis coupled with a minimum cumulative resistance model (MSPA–MCR) based on multi-source data was used to study, on a provincial scale, the ecological security pattern of Ningxia, an ecologically fragile region in the upper reaches of the Yellow River in China. The results show the following: (1) A reasonable classification of ecological sources and ecological corridors is key to constructing hierarchical ecological networks. Classifying ecological sources by replacing patch areas with energy factors and identifying the importance of ecological corridors by modifying the gravity model with the energy factors proposed in this paper could improve the rationality of the hierarchical structure division of ecological networks. (2) Grassland as the substrate vegetation type is an important ecological source type in arid and semi-arid ecologically fragile areas, and forests and lake wetlands are the main ecological source types in mountainous areas and oasis areas, respectively. The study area was located in the arid–semi-arid transitional area, with a variety of ecological types, such as mountain, oasis, and desert. Therefore, the complex ecological source types of forest–grassland–wetland appear in some areas. (3) There are 45 ecological patch groups that can be classified as ecological sources in Ningxia, including 10 primary source groups. The number of primary source groups is small, and their spatial distribution is unbalanced. There are two categories of ecological corridors, the river corridor and the mountain corridor, and the network connectivity is poor. (4) The ecological network structure of Ningxia is presented as an ecological security structure consisting of one belt, three screens, three corridors, and five clusters, forming a hierarchical nested ecological network security structure system. [ABSTRACT FROM AUTHOR]

This paper describes a dynamic and quantitative method of diagnosing and estimating rail corrugation in railway tracks using acceleration data obtained from high-speed comprehensive inspection train. Although the amplitude of rail corrugation is small, it will arouse violent vibration between the wheel and rail under high-speed conditions, and accelerate the structural damage of track-vehicle system components. Combined with high-frequency Axle Box Acceleration (ABA), a time-frequency analysis-based Rail Corrugation Index and Energy Factor method are proposed to diagnose the rail corrugation of high-speed railway. The corrugation amplitude is estimated by the quadratic integral of filtered ABA. The new evaluation method uses the windowed energy index signal of the ABA to replace the original signal, and demodulates the high-frequency discrete response signal into a stable low-frequency energy signal without losing the vibration characteristics. Inverse SSTFT is applied to estimate the amplitude of rail corrugation. High-speed railway application results show that the proposed index can effectively diagnose the rail corrugation dynamically and quantitatively and estimate the degree of it. [ABSTRACT FROM AUTHOR]

This paper focused on the performance monitoring and modeling of a 6.0 kW, 2000 L hybrid direct expansion solar assisted heat pump (DX-SAHP) water heater used for the production of hot water in a university students' accommodation with 123 females. The data of total electrical energy consumed, volume of hot water consumed, ambient temperature, relative humidity, and solar irradiance were obtained from the data acquisition systems and analyzed in conjunction with the energy factor (EF) of the system. A multiple linear regression model was developed to predict the EF. The EF of the hybrid DX-SAHP water heater was determined from the summation of the coefficient of performance (COP) of the heat pump unit and the solar fraction (SF) of the solar collectors. The operations of the hybrid energy system were analyzed based on three phases (first phase from 00:00–08:00, second phase from 08:30–18:30, and third phase from 19:00–23:30) over 24 h for the entire monitoring period. The average EF of the hybrid energy system per day during the second phase of operation was 4.38, while the SF and COP were 0.697 and 3.683, respectively. The developed multiple linear regression model for the hybrid DX-SAHP water heater accurately predicted the determined EF. [ABSTRACT FROM AUTHOR]

Weak magnetic detection technology is an effective method to identify stress-induced damage to ferromagnetic materials, and it especially possesses great application potential in long-distance oil and gas pipeline weld crack detection. In the process of pipeline operation, due to internal pressure and external loads, local stress concentration may be generated, and partial stress concentration may lead to local cracks and expansion of the pipe. In order to improve the accuracy of magnetic signal analysis for ferromagnetic materials under internal pressure, the causes of magnetic signal generation at pipeline welds were analyzed from a microscopic perspective. The distributions of magnetic signals at pipeline welds, weld cracks, and base metal cracks under different internal pressures were numerically analyzed. The variation trends of magnetic signal characteristics, such as peak values of axial and radial components, gradient K, maximum gradient Kmax, and gradient energy factor S(K), were analyzed. In addition, experiments were carried out to verify the numerical data. It was revealed that with the elevation of internal pressure, the peak values of the axial and radial components, gradient K, maximum gradient Kmax, and gradient energy factor S(K) linearly increased. However, the magnitude and average change of S(K) were larger, which can more directly indicate variations of magnetic signals. The radial growth rate νy of S(K) was 3.24% higher than the axial growth rate νx, demonstrating that the radial component of the magnetic signal was more sensitive to variations of stress. This study provided a theoretical and experimental basis for detection of stress-induced damage to long-distance oil and gas pipelines. [ABSTRACT FROM AUTHOR]

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The influences of applied pressure on the structure, mechanics, dislocation, and electronics properties of an FeTi hydrogen storage alloy are theoretically investigated via first-principles calculations. The lattice parameter ratio, elastic constant, Young’s modulus, bulk modulus, shear modulus, ductile/brittle, Poisson’s ratio, anisotropy, Cauchy pressure, yield strength, Vickers hardness and energy factor are discussed versus applied pressure. The results show that the FeTi alloy exhibits good mechanical stability under applied pressure between 0 and 50 GPa, and the mechanical properties are significantly improved under applied pressure, like the resistances to elastic, bulk, and shear deformations, the material ductility and metallicity, as well as Vickers hardness and yield strength. Moreover, the electronic structures reveal that the FeTi alloy has metallic properties and the structural stability of the FeTi hydrogen storage alloy is enhanced at high pressure. This work provides significant value for high-pressure applications of FeTi alloys in hydrogen storage and supply fields.

Important for promoting the integrated protection and systematic management of mountains, rivers, forests, farmlands, lakes, grasslands, and sandy areas, ecological networks form the backbone of the regional ecological security pattern. An improved morphological spatial pattern analysis coupled with a minimum cumulative resistance model (MSPA–MCR) based on multi-source data was used to study, on a provincial scale, the ecological security pattern of Ningxia, an ecologically fragile region in the upper reaches of the Yellow River in China. The results show the following: (1) A reasonable classification of ecological sources and ecological corridors is key to constructing hierarchical ecological networks. Classifying ecological sources by replacing patch areas with energy factors and identifying the importance of ecological corridors by modifying the gravity model with the energy factors proposed in this paper could improve the rationality of the hierarchical structure division of ecological networks. (2) Grassland as the substrate vegetation type is an important ecological source type in arid and semi-arid ecologically fragile areas, and forests and lake wetlands are the main ecological source types in mountainous areas and oasis areas, respectively. The study area was located in the arid–semi-arid transitional area, with a variety of ecological types, such as mountain, oasis, and desert. Therefore, the complex ecological source types of forest–grassland–wetland appear in some areas. (3) There are 45 ecological patch groups that can be classified as ecological sources in Ningxia, including 10 primary source groups. The number of primary source groups is small, and their spatial distribution is unbalanced. There are two categories of ecological corridors, the river corridor and the mountain corridor, and the network connectivity is poor. (4) The ecological network structure of Ningxia is presented as an ecological security structure consisting of one belt, three screens, three corridors, and five clusters, forming a hierarchical nested ecological network security structure system.

This paper considers the 3D printing process as a discontinuous control system and gives a simple and coherent bond stress-slip model for a new and intelligent building 3-D printed concrete. The previous models focused on either the maximal stress or the maximal slip, however, the novel model uses an energy approach by the dimension analysis, so that the main factors affecting the bond stress-slip relationship can be clearly revealed, mainly including the concrete's properties (its porous structure and its strength), the steel bar's properties (its printing direction, its strength, its surface roughness and its geometrical property) and the printing process. It is confirmed that the proposed model, similar to the constitutive relationship in elasticity, plays a key role in concrete mechanics, and it can conveniently explain the observed phenomena from the experiment. [ABSTRACT FROM AUTHOR]

The manufacturing process of cement emits one metric ton of carbon dioxide greenhouse gas. Considering the situation reducing the gas emission without affecting cement production, industrial wastes like metakaolin (MK) can be partially replaced with cement due to high pozzolanic reactivity to arrive the high-strength concrete. This present examination attentions on the obtaining optimum percentage of metakaolin to be substituted for cement proportion and aims to determine the concrete sample’s mechanical characteristics, equivalent CO _2 emissions, and energy factor for environmental advantages through comparison with metakaolin varied from 0% to 20% at 5% incremental rate was determined and compared with the conventional control mix. Concrete samples are tested at the periodical interval of 7, 14, and 28 days in addition results, 5% of metakaolin is the optimum percentage to be replaced for cement in concrete. The negative sign implies that replacing binder with MK gradually decreases energy requirements (−2.16% to −7.74%) as well as carbon dioxide emissions (−4.17% to −15.41%). The use of mineral admixture like high reactive metakaolin additional cementitious elements has a considerable effect and may have an impact on the creation of environmentally friendly, sustainable concrete. In conclusion, effective utilization of high reactive metakaolin in high-strength concrete leads to substantial cost, and reducing global gas emissions eventually reduces energy consumption and a notable decrease in environmental pollution.

This paper focused on the performance monitoring and modeling of a 6.0 kW, 2000 L hybrid direct expansion solar assisted heat pump (DX-SAHP) water heater used for the production of hot water in a university students’ accommodation with 123 females. The data of total electrical energy consumed, volume of hot water consumed, ambient temperature, relative humidity, and solar irradiance were obtained from the data acquisition systems and analyzed in conjunction with the energy factor (EF) of the system. A multiple linear regression model was developed to predict the EF. The EF of the hybrid DX-SAHP water heater was determined from the summation of the coefficient of performance (COP) of the heat pump unit and the solar fraction (SF) of the solar collectors. The operations of the hybrid energy system were analyzed based on three phases (first phase from 00:00–08:00, second phase from 08:30–18:30, and third phase from 19:00–23:30) over 24 h for the entire monitoring period. The average EF of the hybrid energy system per day during the second phase of operation was 4.38, while the SF and COP were 0.697 and 3.683, respectively. The developed multiple linear regression model for the hybrid DX-SAHP water heater accurately predicted the determined EF.

Weak magnetic detection technology is an effective method to identify stress-induced damage to ferromagnetic materials, and it especially possesses great application potential in long-distance oil and gas pipeline weld crack detection. In the process of pipeline operation, due to internal pressure and external loads, local stress concentration may be generated, and partial stress concentration may lead to local cracks and expansion of the pipe. In order to improve the accuracy of magnetic signal analysis for ferromagnetic materials under internal pressure, the causes of magnetic signal generation at pipeline welds were analyzed from a microscopic perspective. The distributions of magnetic signals at pipeline welds, weld cracks, and base metal cracks under different internal pressures were numerically analyzed. The variation trends of magnetic signal characteristics, such as peak values of axial and radial components, gradient K, maximum gradient Kmax, and gradient energy factor S(K), were analyzed. In addition, experiments were carried out to verify the numerical data. It was revealed that with the elevation of internal pressure, the peak values of the axial and radial components, gradient K, maximum gradient Kmax, and gradient energy factor S(K) linearly increased. However, the magnitude and average change of S(K) were larger, which can more directly indicate variations of magnetic signals. The radial growth rate νy of S(K) was 3.24% higher than the axial growth rate νx, demonstrating that the radial component of the magnetic signal was more sensitive to variations of stress. This study provided a theoretical and experimental basis for detection of stress-induced damage to long-distance oil and gas pipelines.

The rational allocation of industrial factors in resource-based cities is a necessary condition for promoting high-quality economic development. To systematically measure the mismatch of industrial factors, this study integrates the production function model and accounting framework of Aoki (2012). The capital, labor, and energy factors are integrated into the overall measurement framework, and the factor mismatch calculation model is innovatively constructed at the city level. To effectively reflect the factor mismatch of different cities, the relative distortion coefficient of factor price is introduced to establish the relationship between the distortion of factor-use cost and effectiveness of resource allocation. The degree and direction of factor mismatch are effectively measured. This study takes China's resource-based cities as the research object. To avoid the impact of the COVID-19 pandemic, data on 114 resource-based cities in China from 2003 to 2018 are selected, and 164 non-resource-based cities are used as the control group to evaluate the factors affecting the transformation of such cities. Regarding the diversity of resource-based cities in China, this study compares the characteristics of factor misallocation in these cities for different growth stages, geographical regions, and dominant resources. Finally, this study finds that on average, the cities' degree of energy misallocation is the most serious, and the degree of labor misallocation ranks second. The degree of capital misallocation ranks the lowest, but the misallocation of various factors is very different in different situations. Therefore, different types of cities should make detailed policy adjustments in various transformation directions according to the calculation results., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Runqun Yu reports financial support was provided by Liaoning Social Science Planning Fund Office., (© 2024 The Authors.)

• A new joint vibro-acoustic method for periodic track short-wave defect identification method is put forward. • Based on ACMD and Gini Index, Energy Factor of Vibration Mode (E VM), Energy Factor of Acoustic Mode (E AM) and Energy Factor of Vibro-acoustic Mode (E VAM) are proposed for describing the energy concentration. • The proposed joint vibro-acoustic analysis method can enhance the common components and retain the unique components of acoustic signal and vibration signal. • By analyzing measured data, the proposed method shows effectiveness in identifying short-wave defect and its time–frequency characteristics. The present track short-wave irregularity inspection and evaluation method, based on the vibration signals collected by accelerators mounted on the axle box of high-speed comprehensive inspection train, is relatively a proven technology. However, with data analysis and check on-site, it finds out that the periodic defects exist in the sections where the dynamic responses are weak. When vibration signals are used for short-wave analysis, it may have the problems of inaccurate frequency identification, lack of energy concentration, etc., which is easy to cause missing or misjudgment of defects. As a result, the stability and robustness of present method need to be enhanced and refined. This article analyzes measured acoustic signals for a supplement to vibration signals. Based on vibration signals of axle box and acoustic signals collected by microphones mounted on the bogie frame of high-speed comprehensive inspection train, a new joint vibro-acoustic method for periodic track short-wave defect identification is proposed. The vibration and acoustic signals are processed and evaluated by Adaptive Chirp Mode Decomposition (ACMD), Gini Index (GI) and modal recombination. Energy Factor of Vibration Mode (E VM), Energy Factor of Acoustic Mode (E AM) and Energy Factor of Vibro-acoustic Mode (E VAM) are introduced for evaluating the periodic component in signals. By analyzing three groups of signals, it proves that, combining vibration and acoustic signals, the energy concentration of periodic components can be enhanced without losing the information of other signal components, and the periodic track short-wave defects can be effectively identified. [ABSTRACT FROM AUTHOR]

Design base shear and lateral force distribution are two important aspects of the seismic design process. Different design methods have been proposed to obtain the design base shear of different types of structures. However, the study related to the lateral force distribution is limited, especially for self-centering (SC) structures. The primary objective of this research is to develop a performance-based seismic design (PBSD) procedure for steel braced frames considering the modified lateral force distribution. Six-story steel braced steel frames are designed to explore the influence of the energy dissipation factor on the lateral force distribution of the frames. Results of nonlinear time-history analyses indicated that the lateral force acting on the roof increases with the decrease in energy dissipation factor. Following the parametric analyses of single-degree-of-freedom (SDOF) systems, the energy factor design spectra are established and the corresponding PBSD procedure for the steel braced frames is proposed. Finally, the four six-story braced steel frames are redesigned using the PBSD procedure with the modified lateral force distribution to illustrate the efficiency of the proposed design method. Analyses results indicate that the steel braced frames designed by the proposed design can satisfy the expected inter-story drift limit with a reasonably uniform distribution of peak inter-story drifts. Furthermore, the 'partial' SC system appears to be a desirable option that effectively controls the residual displacement and peak acceleration responses at the same time, and could achieve a manageable cost control compared to the full SC systems. [Display omitted] • The optimal lateral force distribution of SC and 'partial' SC steel braced frames is investigated. • The energy factor design spectra are established, especially for the 'partial' SC system. • The PBSD procedure considering the modified lateral force distribution for the steel braced frames is proposed. • The 'partial' SC system (e.g., β = 0.75) appears to be a desirable option for the design of steel braced frames. [ABSTRACT FROM AUTHOR]