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Wind power forecasting involves data preprocessing and modeling. In pursuit of better forecasting performance, most previous studies focused on creating various wind power forecasting models, but few studies have been published with an emphasis on new types of data preprocessing methods. Effective data preprocessing techniques and the fusion with the physical nature of the wind have been called upon as potential future research directions in recent reviews in this area. Data enrichment as a method of data preprocessing has been widely applied to forecasting problems in the consumer data universe but has not seen application in the wind power forecasting area. This study proposes data enrichment as a new addition to the existing library of data preprocessing methods to improve wind power forecasting performance. A methodological framework of data enrichment is developed with four executable steps: add error features of weather prediction sources, add features of weather prediction at neighboring nodes, add time series features of weather prediction sources, and add complementary weather prediction sources. The proposed data enrichment method takes full advantage of multiple commercially available weather prediction sources and the physical continuity nature of wind. It can cooperate with any existing forecasting models that have weather prediction data as inputs. The controlled experiments on three actual individual wind farms have verified the effectiveness of the proposed data enrichment method: The normalized root mean square error (NRMSE) of the day-ahead wind power forecast of XGBoost and LSTM with data enrichment is 11% to 27% lower than that of XGBoost and LSTM without data enrichment. In the future, variations on the data enrichment methods can be further explored as a promising direction of enhancing short-term wind power forecasting performance.

Objective To explore the molecular mechanism of neuropathologic damage induced by radiofrequency ablation at different temperatures. Methods This is basic research, and 36 SD rats were used to construct the neuropathological injury model. The rats were subjected to radiofrequency stimulation at different temperatures and were divided into 6 groups according to the temperature injury: 42°, 47°, 52°, 57°, 62°, and 67°C groups. Conduction time, conduction distance, and nerve conduction velocity were recorded after temperature injury. HE-staining was used to observe the histopathological morphology of the sciatic nerve. The expression of SCN9A, SCN3B, and NFASC protein in sciatic nerve tissue were detected by western blot. Results With the increase in temperature, nerve conduction velocity gradually decreased, and neurons were damaged when the temperature was 67°C. HE-staining showed that the degrees of degeneration of neurons in rats at 47°, 52°, 57°, 62°, and 67°C were gradually increased. The expression of SCN9A, SCN3B protein in 57°, 62°, 67°C groups were much higher than that of NC, 42°, 47°, 52°C groups. However, the expression of NFASC protein in 57°, 62°, 67°C groups was much lower than that of the NC, 42°, 47°, 52°C groups. Conclusion There was a positive correlation between temperature caused by the radiofrequency stimulation to neuropathological damage. The mechanism is closely related to the expression of SCN9A, SCN3B, and NFASC protein in nerve tissue caused by heat transfer injury.

The global trends of coal phase-out in response to climate change are meeting obstacles in China, where a stable operation of power-coal supply chains remains essential. How to guarantee the resilience of these supply chains during the low-carbon transition becomes a critical issue. This study aims to recommend corresponding strategies by modelling and analysis. A system dynamics model was developed to analyze scenarios of China’s power-coal supply from 2021 to 2060. The results indicated that, firstly, the capacity redundancy of coal mines will increase from 1.13 to 1.32 before 2045, with the rising power-coal demand and its volatility, followed by a sharp decrease after that, in which demand falls in all scenarios. Secondly, increasing coal stock in each link can effectively reduce capacity redundancy of coal mines and imports during the period of rising demand, resulting in 250 million tons of coal mine capacity reduction, but will lead to an opposite result when demand falls. Finally, under high demand fluctuations, coal transport capacity will become a key constraint. It is recommended that China must improve the capacity redundancy of coal mines, coal stock, and coal transport in the near-term, as well as enhance long-term planning to carefully coordinate these factors during the whole process of low-carbon transition.

China has a vast territory, so the energy resource endowments of different regions in the country are significantly varied. Promoting regional energy revolution based on local conditions is an effective way to break the bottlenecks that restrict China’s energy development. This study analyzes the current situation of energy development from the aspects of energy production, consumption, and distribution, and investigates the differences regarding energy consumption intensity and the driving force for energy consumption growth in the core regions (i.e., the Beijing–Tianjin–Hebei region, Yangtze River Delta, Pearl River Delta, old industrial bases, the Central China, energy-rich areas, and Southwest China). The medium- and long-term energy development trends and strategic focuses of these regions by 2035 are analyzed. Specifically, the Beijing–Tianjin–Hebei region should focus on the coordinated development of energy, economy, and environment; an energy system with regional linkage should be formed and optimized in the Yangtze River Delta; the Pearl River Delta can strive to build itself as a clean energy production, storage, and transportation base; economic transformation should be promoted in the old industrial bases through value increment and diversification of energy resources; Central China should establish itself as an integrated energy hub; the energy-rich areas should build itself as a green and sustainable energy security base; and clean energy consumption should be encouraged in Southwest China. To coordinate energy development in various regions, China should fully consider the significant differences in local conditions, promote social development and ecologicalprotection with the regional energy revolution, and encourage regional cooperation in energy.

A high-quality methane emission estimation in China’s oil and gas sector is the basis of an effective mitigation strategy. Currently, the published emission data and studies of China’s oil and gas sector only provide estimations of total emissions, which is not enough for good analysis of the trend and impact factors for the instruction of emission mitigation activities. The main problem is that published data for oil and gas infrastructure in China is incomplete, which makes it difficult to apply the conventional greenhouse gas inventory compiling method and the uncertainty estimation strategy. Therefore, this paper aims to develop a method to estimate infrastructure data using all available data, including partial data for the infrastructure, national production and consumption of oil and gas, and production and production capacity data of oil and gas enterprises, and then uses a Monte Carlo-based method to generate a source-based inventory and uncertainty analysis of methane emission for China’s oil and gas industry from 1995 to 2018. We found that methane emission increased from 208.3 kt in 1995 to 1428.8 kt in 2018. Methane emission in 2018 has an uncertainty of about ±3%. Compared to former studies, our research found that the production stage of natural gas is the main contributor, which is further driven by the growth of natural gas production. The mitigation potential introduced by technology development on methane emission remains large.

The emission estimation of the oil and gas sector, which involves field test measurements, data analysis, and uncertainty estimation, precedes effective emission mitigation actions. A systematic comparison and summary of these technologies and methods are necessary to instruct the technology selection and for uncertainty improvement, which is not found in existing literature. In this paper, we present a review of existing measuring technologies, matching data analysis methods, and newly developed probabilistic tools for uncertainty estimation and try to depict the process for emission estimation. Through a review, we find that objectives have a determinative effect on the selection of measurement technologies, matching data analysis methods, and uncertainty estimation methods. And from a systematic perspective, optical instruments may have greatly improved measurement accuracy and range, yet data analysis methods might be the main contributor of estimation uncertainty. We suggest that future studies on oil and gas methane emissions should focus on the analysis methods to narrow the uncertainty bond, and more research on uncertainty generation might also be required.

The input–output table and input–output method have been widely used to understand complex economic structures and are often used in cross-disciplinary research between economics and other disciplines, such as analysis of embodied energy, carbon footprints, the water–food nexus, etc. However, when researchers present these results to audiences, especially policymakers, they often lack an effective visualization tool to present (1) the full picture of the input–output table, (2) the complicated upstream–downstream nexus, and (3) the input–output relationships between the economic sectors. Therefore, a better visualization method is developed to solve this problem. We propose mapping an input–output table into a Sankey diagram, a so-called monetary allocation Sankey diagram. We first designed the mapping structure of a monetary allocation Sankey diagram according to the general structure of an economic monetary input–output table to establish the correspondence nexus between the table and diagram. We used China as a case study to demonstrate the usage of the monetary allocation Sankey diagram. The purpose of the monetary allocation Sankey diagram is to help people understand the input–output table in a short time and quickly grasp the big picture of the economic system. To verify whether this goal is achieved, we presented and applied these Sankey diagrams on different occasions and obtained evaluations from scholars from different academic backgrounds. The evaluation shows that the monetary allocation Sankey diagram is not only a visualization result of the input–output table but also a miniature model of the economic system, which allows people to “truly observe” the complex input–output relationship and upstream–downstream nexus in the economic system. Researchers can quickly grasp the main features of the economic system by observing the miniature model, or they can use this miniature model as an auxiliary tool to introduce the economic system and its inherent complex relationships to the audience.

In China today, as well as other areas of the world, new technologies that apply multi-energy cooperative utilization and seek commercialization face the challenge of economic uncertainty. In this context, business models have a significant influence on the techno-economic performance of the technology projects. By using the solar-heat pump water heater as a case study example, the aim of this study is to develop a techno-economic model to evaluate and compare the techno-economic performance of multi-energy cooperative utilization under different business models to be able to recommend steps for improved commercialization going forward. The results indicate that in the model called “no third party intervention,” where the transaction is solely between a single enterprise operator and the user, the investment value of this technology is weak from the user's point of view. Therefore, government incentive is needed at a high ratio of subsidy to entice the user to purchase it (or this technology). When energy service companies become involved in the transaction, third party firms that purchase the products and basically lease them to customers not only avoid any high initial investment cost but also improve the economics of the project by receiving additional value-added services. In this circumstance, only a reasonable government subsidy is needed and then, the project has an investment value and benefits for all stakeholders which are involved.

Over the past twenty years, thin film lubrication (TFL) theory has been used to characterize the molecular behaviors in lubrication films thinner than 100 nm, effectively bridging the gap between elastohydrodynamic lubrication and boundary lubrication. Unfortunately, to date, the TFL molecular model proposed in 1996 has not been directly proven by experimental detection. Herein, a method based on surface-enhanced Raman spectroscopy was developed to show both the packing and orienting of liquid molecules in the TFL regime. By trapping liquid crystal molecules between a structured silver surface and a glass surface, molecular ordering states dominated by shear effect and surface effect were successfully distinguished. A nanosandwich structure consisting of an adsorbed layer, an ordered-molecule layer, and a fluid layer was demonstrated. Molecule imaging in TFL was achieved. Our results illustrate the molecular behaviors and lubrication mechanism in nanoconfined films and facilitate the lubrication design of nanoelectromechanical and microelectromechanical systems.

The mechanical performances of traditional notched HDPE pipe (NHP) with various groove depths and shapes, including U-type, V-type and L-type (linear type), are critical for the safety assessment. However, some important mechanical performances, such as the limit load, creep, low cycle fatigue or high cycle fatigue may be not convenient to test by the NHP specimen. A novel notched HDPE ring (NHR) specimen was designed to test the mechanical performances of NHP, and the tested results were compared with those data obtained by NHP specimens, finite element simulation and theoretical prediction. Results show that the simulated and predicted ultimate loads of NHR specimens with various groove shapes and depths are in good agreement with experimental data. Additionally, the strength reduction factors of NHP and NHR specimens are very close to each other when the depth ratio is less than 0.4 for various grooves. It is of interest that the static creep lives of NHR specimens with U-type and V-type notches are relatively shorter than that of the specimens with the L-type groove. Therefore, the NHP specimen can be replaced by the proposed NHR specimen to test mechanical properties for convenience.

Analysis of the change of overall energy efficiency performance of an energy system is a fundamental work for the energy-saving policymaking. However, previous studies seldom focus on energy stages from useful energy to final service, while most attention are paid on stages from energy source to useful energy. In this paper, we develop a high-resolution the Societal Exergy Analysis and Logarithmic Mean Divisia Index (SEA-LMDI) method to analysis changes and driving factors of the aggregate exergy efficiency, in which the boundary of the SEA is extended to passive systems and final services, and a LMDI decomposition method is developed to quantify contributions of efficiency factors and structure factors of all six stages on the aggregate exergy efficiency. A case study of China during 2005–2015 reveals that: (a) the aggregate exergy efficiency from energy source to final service is only from 3.7% to 4.8% during 2005–2015, showing a huge theoretical potential of efficiency improvement. (b) Large passive losses are identified in passive systems and nearly 2/3 of useful energy can be theoretically saved by improving passive systems. (c) Deep analysis of industrial coal-fired boilers indicates that the internal structural adjustments are also important for the aggregate improvement.

Worsening climate change has brought grave challenges to global energy development. All countries need to make urgent joint actions to speed up low-carbon transition of the energy sector. China, as the largest energy-related greenhouse gas emitter, plays a crucial part in global low-carbon energy transition. Clear strategic guidance is one of the indispensable factors for the country’s successful transition. With the integration of energy system in mind, this chapter builds on the basic concepts of energy transition strategy and framework of system analysis to elaborate on China’s energy transition strategy amid global climate change. The chapter contains three sections: energy challenges in China, the history, recent trends and future path of China’s energy system, and policy recommendations for energy governance and energy markets. Overall, the challenge of China’s energy transition in the context of global climate change lies not only in the call to expedite carbon emission reductions in the energy system, but also in the need to address other energy issues such as energy equity, energy security, and environmental protection. To solve all these issues, it must consider the unique evolution and changing pattern of China’s energy system itself, follow the mechanism, and meticulously craft the strategy of energy transition (energy revolution) that suits the national situation. Under the policy objectives of the energy revolution, such as capping total energy consumption, peaking carbon emission, and increasing the share of non-fossil energy, China must accommodate energy system integration relative to coordination between energy and economy, between energy and infrastructure and between energy and regional development. To this end, this chapter envisions the “3+1” energy system integration, and proposes to build a regional smart energy system that features the blend of “smart energy farms—smart energy towns—smart energy industrial parks—smart energy transportation networks”. However, this poses new challenges to the existing energy governance system and energy market management. Therefore, it’s essential for China to empower energy planners, spur bottom-up energy innovation, remove the barriers to cooperation between the energy industry and enterprises, and redouble efforts to strengthen the energy management information system and dedicated think tanks in the energy sector.

Controlling energy consumption to reduce greenhouse gas emissions has become a global consensus in response to the challenge of climate change. Most studies have focused on energy consumption control in a single region, however, high-resolution analysis of energy consumption and personalized energy policy-making, for multiple regions with differentiated development, have become a complicated challenge. Using the logarithmic mean Divisia index I (LMDI) decomposition method based on energy allocation analysis (EAA), this paper aims to establish a standard paradigm for a high-resolution analysis of multi-regional energy consumption and provide suggestions for energy policy-making, taking 29 provinces of China as the sample. The process involved three steps: (1) determination of regional priorities of energy consumption control by EAA, (2) revealing regional disparity among the driving forces of energy consumption growth by LMDI, and (3) deriving policy implications by comparing the obtained results with existing policies. The results indicated that 29 provinces can be divided into four groups, with different priorities of energy consumption control according to the patterns of coal flows. Most provinces have increasing levels of energy consumption, driven by increasing per capita GDP and improving living standards, while its growth is restrained by decreasing end-use energy intensity, improving energy supply efficiency, and optimization of industrial structures. However, some provinces are not following these trends to the same degree. This indicates that policy-makers must pay more attention to the different driving mechanisms of energy consumption growth among provinces.

The channels may be formed in the unconsolidated sands reservoir due to formation failure during high-pressure water injection or frac-packing. Based on the continuum mechanics, a mathematical model has been established to simulate the formation process of big channels in unconsolidated sands reservoir during fluid injection. The model considers the effect of reservoir heterogeneity, solid particles erosion, and deposition. The dynamic formation process of channels around the borehole and its influencing factors are analyzed by this model. The results indicate that the seepage erosion plays a very significant role in the formation of the channels during fluid injection for the unconsolidated sands with extremely low strength. The formation of the channels is closely related to the duration of fluid injection, injection pressure, reservoir heterogeneity, formation plugging, and critical fluid velocity. The long channels are more likely to form as injection time increases. Higher injection pressure will lead to higher flow rate, thus eroding the solid particles and forming big channels. The increase of the rock strength will enhance the value of critical fluid velocity, which makes it difficult for the occurrence of erosional channelization. The near-wellbore damage of the formation will decrease the flow rate, and the preferential flow channels are less likely to be induced under the same injection pressure when compared with undamaged formation. In addition, we also found that the reservoir heterogeneity is essential to the formation of preferential flow channels. The channels are especially prone to be formed in the regions with high porosity and permeability at the initial time. The study can provide a theoretical reference for the optimal design of high-pressure water injection or frac-packing operation in the unconsolidated sands reservoir.

To systematically analyze energy-related carbon emissions from the perspective of comprehensive energy flow and allocate emissions responsibility, we introduce energy allocation analysis to carbon flow process based on Sankey diagrams. Then, to quantitatively compare different diagrams and evaluate the structural changes of carbon flow, we define changes from three dimensions including total amount change, relative growth rate and occupation ratio change (TRO), propose TRO index. The method is applied to China’s case study from 2005 to 2015. We map China’s energy-related carbon flow Sankey diagrams with high technical resolution from energy sources, intermediate conversion, end-use devices, passive systems to final services, and conduct TRO index decomposition by stages. The results indicate that in energy sources, the emission share of coal has declined due to energy transition although coal is still the largest contributor to China’s energy-related carbon emissions. In passive systems, the factory passive systems are the largest contributors, among them, emission reduction should focus on the steel, non-ferrous and chemical industries; the building passive systems should pay attention to household appliances; the vehicle passive systems should focus on cars. In final services, the demand for structural materials is the strongest driving force for carbon emissions growth.

The measurement and allocation of carbon emission responsibilities is a fundamental issue in China’s low-carbon development. However, existing studies of embodied carbon do not sufficiently consider the sectoral energy structure. In this work, we developed a high-resolution calculation method for embodied carbon that embeds the sectoral energy structure into traditional input–output methods, thus expanding the driving factors of SDA decomposition. Based on this method, we calculated the quantity, final consumption structure, and energy structure of embodied carbon in China’s 28 sectors from 2002 to 2018, drew a carbon emissions allocation Sankey diagram of China in 2018, and calculated the SDA decomposition results for 2002–2010 and 2010–2018. The results indicate that fixed capital formation was still the top contributor of embodied carbon, and it caused more coal consumption. “Construction for fixed capital formation” and “other services for domestic consumption” were the two most important drivers of carbon emissions. The final consumption quantity and energy intensity were the main factors that promoted and inhibited the growth of embodied carbon, respectively, while the effects of the input–output structure, sectoral energy structure, and carbon emission coefficient on reducing carbon emissions were obvious after 2010. This also revealed that policymakers should formulate differentiated emission reduction strategies according to the carbon emission characteristics of key sectors.

Summary A growing number of governments are pledging to achieve net-zero greenhouse gas emissions by mid-century. Despite such ambitions, realized emissions reductions continue to fall alarmingly short of modeled energy transition pathways for achieving net-zero. This gap is largely a result of the difficulty of realistically modeling all the techno-economic and sociopolitical capabilities that are required to deliver actual emissions reductions. This limitation of models suggests the need for an energy-systems analytical framework that goes well beyond energy-system modeling in order to close the gap between ambition and reality. Toward that end, we propose the Emissions-Sustainability-Governance-Operation (ESGO) framework for structured assessment and transparent communication of national capabilities and realization. We illustrate the critical role of energy modeling in ESGO using recent net-zero modeling studies for the world's two largest emitters, China and the United States. This illustration leads to recommendations for improvements to energy-system modeling to enable more productive ESGO implementation., Graphical abstract, Energy resources; Energy policy; Energy systems

Uniaxial stress-controlled ratcheting experiments of PTFE (polytetrafluoroethylene) under cyclic compressive loads with multiple load steps were performed. The influence of stress rate, temperature, stress amplitude, loading sequence and peak holding on the compressive ratcheting behavior have been discussed systematically. Results indicate that ratcheting deformation increases significantly when enhancing temperature and stress amplitude and reducing stress rate. Only a slight, accumulated deformation occurs during the first 20 or so cycles at room temperature (RT), but it always turns to shakedown. Moreover, ratcheting strain is clearly influenced by the loading sequence. When greater compressive deformation was obtained during the prior load step due to a greater stress level (such as higher temperature or a lesser stress rate), increased compressive strain hardening and deformation resistance could be produced, which in turn restricts or even reduces ratcheting deformation in the pursuing load step. It is of great interest that no initial cyclic stress strain curve was observed under cyclic compression at peak holding time. This indicates that creep recovery due to anelastic relaxation decreases the ratcheting rate of PTFE material under compressive creep-fatigue conditions. This research provides an important testing approach and data for PTFE material subjected to repeated compressive loads influenced by temperature modulation.

Compressive ratcheting response and creep of non-asbestos fibre composite are tested based on a designed compression–compression clamp for plate-shape specimens. The influences of temperature, stress amplitude and stress rate are discussed in detail. A two-stage constitutive model is developed to describe the compression-resilience relationship of non-asbestos fibre composite. Results present that a crescent-shaped stress–strain relationship of non-asbestos fibre composite is observed under repeated compression, and the proposed two-stage constitutive model can predict the compression-resilience curve for the first cycle very well under various temperatures and stress rates. Additionally, the ratcheting strain of non-asbestos fibre composite obviously enhances with increasing the temperature. However, it has a little change when the stress rate and stress amplitude are varied based on the experimental data. The ratcheting strain rate per cycle reduces promptly during about the first 75 cycles, and it is always less than 1 × 10−4 per cycle during the subsequent cycles and tends to shakedown. Moreover, the ratcheting strain with small stress amplitude is very close to the creep deformation at the same testing time and peak stress under different temperatures. This indicates that the ratcheting strain of non-asbestos fibre composite under fatigue loads with small stress amplitude can be evaluated equivalently by the corresponding creep deformation with high precision.

Possession of motor vehicles in China has been rising fast, along with continuous economic growth, social development and improvements in living standards, causing severe energy and environmental stress. To relieve the stress, China is promoting electric vehicles as good alternatives to conventional vehicles. By 2020, the accumulated production and sales of electric vehicles are expected to reach five million. Large-scale connection of electric vehicles to the power grid would inevitably bring challenges to the power sector. In this paper, an electric vehicle and multi-region load-dispatch grid-structure-based (EVMLG) mathematical model is presented, aiming to investigate the interaction between electric vehicles and the power sector. Impacts of charging behaviors are carefully considered. Through case studies, we conclude that (1) the development of electric vehicles will influence regional generation portfolio and operation pattern of the power sector, and increase the utilization of renewables, (2) guided charging can adapt to the power sector, and lead to better economic and environmental benefits, (3) electric vehicles are suitable to be deployed in resource-rich regions, and (4) the development potential of electric vehicles in China is huge from the viewpoint of power supply capacity.

The modified Ohno and Abdel-Karim nonlinear kinematic hardening model considering cyclic hardening and creep effect are developed to investigate the deformation and residual stress of multilayered systems subjected to cyclic thermal and mechanical loads. Results reveal that, if the creep behavior is considered, significant stress relaxation takes place during about the first several cycles, and the accumulated strain of multilayered systems under deformation-controlled loads finally remains constant, which leads to shakedown. Remarkable changes of the residual stress, location of neutral axis and curvature of Si-Cu beams are observed during about the first 100 cycles. Therefore, the proposed model can be used for the engineering design of multilayered systems under complex loads.

Accumulated deformations of polytetrafluoroethylene (PTFE) gaskets under cyclic stress-controlled compressive loads considering temperatures and stress rates are tested. Results present that the accumulated compressive deformation of PTFE gaskets becomes load rate independent when the stress rate is less than 0.1 MPa/s under various temperatures. The compressive deformation accumulates during the initial 50 or more cycles, but it always turns to shakedown subsequently under the experimental conditions. Moreover, the accumulated strain is sensitive to temperature due to material softening and time-dependent creep, especially when the temperature is over 100 °C. This research provides important data for the safety assessment of sealing joints with PTFE gaskets.

The low-carbon development of China’s iron and steel industry (ISI) is important but challenging work for the attainment of China’s carbon neutrality by 2060. However, most previous studies related to the low-carbon development of China’s ISI are fragmented from different views such as production-side mitigation, demand-side mitigation, or mitigation technologies. Additionally, there is still a lack of a comprehensive overview of the long-term pathway to the low-carbon development of China’s ISI. To respond to this gap and to contribute to better guide policymaking in China, this paper conducted a timely and comprehensive review following the technology roadmap framework covering the status quo, future vision, and key actions of the low-carbon development of the world and China’s ISI. First, this paper provides an overview of the technology roadmap of low-carbon development around the main steel production countries in the world. Second, the potential for key decarbonization actions available for China’s ISI are evaluated in detail. Third, policy and research recommendations are put forward for the future low-carbon development of China’s ISI. Through this comprehensive review, four key actions can be applied to the low-carbon development of China’s ISI: improving energy efficiency, shifting to Scrap/EAF route, promoting material efficiency strategy, and deploying radical innovation technologies.

This paper quantifies the exergy losses of coal-based series polygeneration systems and evaluates the potential efficiency improvements that can be realized by applying advanced technologies for gasification, methanol synthesis, and combined cycle power generation. Exergy analysis identified exergy losses and their associated causes from chemical and physical processes. A new indicator was defined to evaluate the potential gain from minimizing exergy losses caused by physical processes—the degree of perfection of the system’s thermodynamic performance. The influences of a variety of advanced technical solutions on exergy improvement were analyzed and compared. It was found that the overall exergy loss of a series polygeneration system can be reduced significantly, from 57.4% to 48.9%, by applying all the advanced technologies selected. For gasification, four advanced technologies were evaluated, and the largest reduction in exergy loss (about 2.5 percentage points) was contributed by hot gas cleaning, followed by ion transport membrane technology (1.5 percentage points), slurry pre-heating (0.91 percentage points), and syngas heat recovery (0.6 percentage points). For methanol synthesis, partial shift technology reduced the overall exergy loss by about 1.4 percentage points. For power generation, using a G-class gas turbine decreased the overall exergy loss by about 1.6 percentage points.

Low cycle fatigue and ratcheting deformation of 25Cr2MoVA steel under cyclic tension were tested at 550°C. The effects of stress rates for 0·1, 0·5, 2·5, 5, 10, and 40 MPa s−1 on ratcheting effect ...

This manuscript analyzes the influencing factors of energy consumption growth in Guangdong Province using the logarithmic mean Divisia index I (LMDI) decomposition method developed based on the physical processes of energy utilization from the primary energy supply to end-use sectors. By introducing the input-output method for mapping the energy allocation diagrams of Guangdong Province, we derive the primary energy quantity conversion factors, which establish the connection between end-use energy consumption and primary energy consumption. These factors are used to develop an LMDI decomposition method suitable for analyzing the energy consumption growth of this region. The method is subsequently applied to analyze the factors influencing energy consumption growth in Guangdong Province from 2004 to 2014. The results indicate that the growth of GDP per capita and population are the dominant factors driving energy consumption growth, while the improvement of electricity supply efficiency is the main factor inhibiting energy consumption growth.

Uniaxial stress-controlled ratcheting behaviors of expanded PTFE (ePTFE) under cyclic compressive loads were tested. The effects of temperature, stress rate and mean stress on the ratcheting behaviors of ePTFE considering multiple load paths were discussed in detail. Results present that the steady ratcheting strain is rate-independent when the stress rate is less than about 0.1 MPa/s, while it approximately linearly decreases with increasing the stress rate for greater stress rate. Additionally, the steady ratcheting is temperature-independent when the temperature is greater than about 150 °C, but it nearly linearly increases with enhancing the temperature for lower temperature. Especially, the stress rate almost has little effect on the ratcheting strain of ePTFE at 200 °C. Moreover, the accumulated ratcheting strain enhances rapidly in about the first 80 cycles, and subsequently tends to shakedown in the subsequent cycles for each load path. Furthermore, if a higher stress is used in the prior cycling, the greater ratcheting strain may be produced, and a negative ratcheting strain rate can be obtained in the subsequent cycling with lower mean stress due to the greater strain hardening and deformation resistance produced by the previous higher stress.

The utilization scale of biomass solid densified fuel (BSDF) in China is still far from reaching the 2020 target of the national plan. Promoting the utilization of pellet fuel from corn straw (CSPF) is an effective way to increase the utilization of BSDF considering its resource potential and convenience for distributed use. To enhance scientific support for the corresponding policy research, this manuscript presents a life cycle assessment (LCA) and economic evaluation of CSPF through a case study in Jilin Province. The results indicate that the utilization of CSPF in this case study can eliminate 90.46% of the life cycle GHG emissions by replacing coal burning. A CSPF project designed with a production capacity of 50,000 tons/year based on corn straw resources of five neighboring villages can be economically viable, but a smaller project with a capacity of 10,000 tons/year based on corn straw resources of a single village will have a poor economic outcome. Further encouraging the use of CSPF among industrial and commercial users and applying carbon trading mechanism for CSPF projects can effectively improve the economy of smaller projects to further promote the deployment of CSPF technologies.

Compressive creep-fatigue experiments on PTFE gaskets with small stress amplitude were tested. The effects of peak holding times and temperatures on creep-ratcheting behaviors were further discussed. Results showed that at room temperature, the accumulated creep-ratcheting strain corresponding to 400 cycles for peak holding 1min is nearly 1.06 times that for peak holding time 0.5min and 1.3 times that without peak holding. While, at 100 °C, 150 °C and 200 °C, they are almost 1.1 times and 1.6 times, 1.1 times and 1.7 times, 1.05 times and 1.9 times, respectively. This means although the accumulated creep-ratcheting strains for peak holding 0.5min and 1min are very close to each other, but short peak holding time still has obvious effect on the accumulated deformation comparing that without peak holding. Moreover, the creep-ratcheting deformation with short peak holding time and small stress amplitude for PTFE gaskets can be simply estimated by the corresponding compressive static creep strain at the same peak stress in practical engineering with relatively good accuracy.

Low cycle fatigue and ratcheting deformation of 35CrMo steel under uniaxial stress-controlled loading were investigated at 500 °C. The effects of stress rates for 0.125 MPa/s, 0.5 MPa/s, 2.5 MPa/s, 10 MPa/s, 25 MPa/s and 40 MPa/s, and peak stresses σmax for 200 MPa, 300 MPa, 400 MPa and 500 MPa, were discussed in detail. Results indicated that the ratcheting strain curve versus cyclic number is similar to traditional static creep curve with three stages and the ratcheting stress rate is lower than the static creep rate with the same peak stress. Shakedown behavior occurs when σ is greater than or equal to 2.5 MPa/s for σmax = 200 MPa, but ratcheting happens for the other loads tested according to the method proposed by the Committee on Three Dimensional Finite Element Stress Evaluation (C-TDF). Moreover, the viscous stress component σv increases significantly with the decrease of stress rate, which represents the ratcheting deformation of 35CrMo steel is obviously time-dependent under high temperature. Furthermore, stress rate has little effect on fatigue life when the stress rate is less than 2.5 MPa/s, while the fatigue life increases exponentially with the increase of stress rate when the stress rate is greater than 2.5 MPa/s at σmax = 500 MPa. It is of interest that the maximum fracture strains for various stress rates remain approximately constant, and the tested average value is 11.6%.

Power demand in China has increased rapidly in the past decade, and it is projected to grow even further. To gain insights into how this demand growth could optimally be met, addressing regional differences such as resource distribution and power demand, is crucial. For long-term planning purposes, using a multi-regional mathematical model that divides China's power sector into regions overcomes the limitations of viewing as a single network. Reflecting how inter-regional power transmission could best be utilized is critical in understanding how flows between regions could be optimised. In this paper, a multi-regional model that reflects actual grid infrastructure with an objective function to maximize accumulated total profits gained by the power generation sector from 2013 to 2050 is proposed. A case study is provided to illustrate how inter-regional power transmission could influence the regional deployment of technologies under different policy scenarios. The results show that energy subsidies and national targets will remain important to the deployment of renewable energy in both the short and long term. In addition, potential downside implications of lower demand growth on the long-term prospects of long-distance inter-regional power transmission and options, such as more flexible electricity pricing mechanisms, to limit the effects are discussed.

Sealing performance and heat loss are important factors for pipe flange joints (PFJs) subjected to medium or high temperatures. Heat loss is of great interest in practical engineering for uninsulated PFJs. Since an insulation layer may degrade the sealing performance of PFJs, heat loss of PFJs was tested and simulated considering various ambient temperatures of −10 °C, 0 °C, 10 °C, 20 °C, 30 °C, and 40 °C, with wind speeds of 0 m/s and 3 m/s and flange joint target temperatures of 200 °C, 300 °C, and 400 °C. It is worth noting that the experiments were performed during summer for high ambient temperatures and during winter for low ambient temperatures. As expected, the steady temperature slightly increases with the increase of external ambient temperature. For the same flange joint temperature, a 3 m/s wind speed decreases significantly the steady temperature, especially when the higher target temperature is applied. If the external wind speed is 3 m/s and the flange joint target temperatures are 200 °C, 300 °C, and 400 °C, respectively, the heat loss increases by approximately 38.4%, 30.7% and 23.6% when the ambient temperature changes from 30 °C to 10 °C. Moreover, the simulated temperatures agree well with the tested temperatures in most cases, and the average error is approximately 8%. The energy saving efficiency under the windless condition is approximately on average 26% higher than that with a wind speed of 3 m/s.

In response to climate change and to achieve global sustainable development, countries should accelerate the transition of their energy systems. In order to clearly understand the underlying mechanism of the transition, it is necessary to investigate the structural changes along energy flow processes and find the driving factors. This paper proposes a quantitative method based on energy allocation Sankey diagrams and index including total amount change, relative growth rate and occupation ratio change (TRO) to evaluate the structural changes of energy flow process and presents a case study of China from 2005 to 2015. Firstly, China’s energy flow process in 2015 was mapped from energy sources, intermediate conversion, end-use devices, passive systems to final services in the form of a Sankey diagram. Secondly, based on TRO index, this diagram was compared with a previous one of 2005 to reveal and evaluate structural changes in the past decade. Finally, the driving factors of these changes were discussed from different perspectives. The main changes from energy sources level are the reduction of coal and the increase of natural gas, from final services level are the reduction of thermal comfort demand and the increase of structural materials (especially that from chemical industry). The key factors driving these changes are the infrastructure construction of natural gas, rapid urbanization, improvement of energy efficiency of buildings and the people’s pursuit of high-quality life.

The analytical pretightening force range of flange joints in a pipeline was deduced based on the allowable gasket stress and flange rotation angle considering the nonlinear compression resi...

In the numerical simulation of welding residual stress (WRS), the thermal fields distribution of the weld beads during welding process is the basic data to calculate the residual stress due to thermal expansion and extraction. Different welding heat input control method had been proposed and used in the WRS finite element method (FEM) analysis, such as input based on theory, input controlled by temperature monitoring point and so on. Some disadvantages like less calculating efficiency, unexpected temperature variation have been found in these methods. Based on the study of the FEM result of temperature distribution through the weld butter field by using constant unit heat input, the heat transfer activities of each weld bead were researched. And a novel heat input fitted equation was proposed to describe the suitable heat input data for each weld bead of the welding process. More reliable and uniform melting temperature of weld beads with different location could be achieved. And the welding residual stresses from different welding thermal field of theory method, temperature monitoring point method, and novel heat input equation method are compared with the measured WRS results. The results show that the WRS achieved from the novel heat input equations is close to the measured result and has more computational efficiency. The uncertain WRS data used for probability safety assessment were also proposed based on the FEM results with the novel heat input equation method.

Increased glycolysis in tumor cells is associated with increased risk of tumor progression and mortality. Therefore, disruption of glycolysis, one of the main sources of cellular energy supply, can serve as a target for suppressing tumor growth and progression. Of note, hexokinase-2 (HK2) plays vital roles in glucose metabolism. Moreover, the expression of HK2 alters the metabolic phenotype and supports the continuous growth of tumor cells, making it an attractive target for cancer therapy. Quercetin (QUE), a bioactive flavonoid, has a profound anti-tumor effect on hepatocellular carcinoma (HCC), but the precise underlying mechanism of this effect is unclear. In the present study, we reported that QUE inhibited the proliferation of HCC cells that relied on aerobic glycolysis. We further found that QUE could decrease the protein levels of HK2 and suppress the AKT/mTOR pathway in HCC cells. In addition, QUE significantly restrained the growth of HCC xenografts and decreased HK-2 expression in vivo. Taken together, we have revealed that QUE suppresses the progression of HCC by inhibiting HK2-dependentglycolysis, which may have a promising potential to be an effective treatments for HCC, especially for those patients with high HK2 expression.

The mechanical properties of medical grade ultrahigh molecular weight polyethylene (UHMWPE) are critical for the safety and integrity of UHMWPE implantation. Accordingly, the mechanical features of UHMWPE are tested under repeated stress-controlled and strain-controlled compression at room temperature. Some important effect factors, such as stress rate, mean stress, stress amplitude, strain rate, mean strain, strain range and multiple load steps are further considered in detail. Results indicate that the lower stress rate causes the greater accumulated plastic strain and the accumulated plastic strain rate becomes increasingly lower with increasing number of cycles. The strain range and accumulated plastic strain rate decrease rapidly in the first stage, and then become almost steady during the second stage. Especially, the accumulated plastic strain rate per cycle for each case is less than 0.01 %/cycle after the initial 100 cycles. This means that the plastic strain accumulates very slowly and the shakedown behavior always occurs. Moreover, obvious cyclic softening and stress relaxation behaviors can be observed under cyclic strain-controlled compression during the first 50 cycles. This indicates that the accumulated plastic stain in the initial 100 cycles and the cyclic stress relaxation during the first 50 cycles should be assessed for the functionality of UHMWPE implantation.