The Energy Efficiency Rebound Effect in China from Three Industries Perspective

AbstractBased on the panel data of three industries in China, this paper calculates the energy rebound effect arising from energy efficiency improvement, by stripping the rebound of energy usage caused by industrial restructuring from model. Results indicate: the similarity between them demonstrating energy efficiency rebound effect as the main component of energy rebound effect; the delayed rebound peak of the secondary industry reflects its lagged respond to changes in energy efficiency; with regard to the peak value in 2009 when calculating the whole nation, author concerns it with the intensification in investment on basic industries and relaxation of restriction over high energy consumption enterprises; the relatively larger value of energy efficiency rebound in China can not be ignored by policy-maker

Revealing microbial processes and nutrient limitation in soil through ecoenzymatic stoichiometry and glomalin-related soil proteins in a retreating glacier forefield

The glacial retreat is observed and predicted to increase in intensity especially in high-elevation areas as a result of global warming, which leaves behind a primary succession along soil chronosequences. Although soil microbes have been recognized as main drivers of ecological and evolutionary processes, our understanding of their effects on nutrient biogeochemistry during primary succession remains limited. In this study, we investigated changes in the microbial community structure, ecoenzymatic stoichiometry, and glomalin-related soil protein (GRSP) accumulation in the Hailuogou Glacier Chronosequence, located on the eastern Tibetan Plateau. We wanted to reveal the effects of nutrient limitation on soil microbes and the relative contributions of edaphic and biotic factors. The results showed that with an increasing soil age, there was a steady increase in the microbial biomass and a shift from a bacterial to fungal dominated pattern. Soil enzyme stoichiometry and analyses on threshold elemental ratios revealed that microbial activities are limited by carbon and nitrogen during the early successional stage (3-52 years), while phosphorus was the main limiting factor during later stages (80-120 years). Moreover, the redundancy analysis and structural equation modeling suggested that during early stages edaphic factors had a greater impact on microbial processes, while the vegetation factors were most influential during the last two stages. Overall, these results highlighted the importance of integrating knowledge of the microbial community structure, soil enzyme activities and GRSP to gain a holistic view of soil-plant microbe interactions during ecosystem successions.Peer reviewe

Distinct co-occurrence patterns and driving forces of rare and abundant bacterial subcommunities following a glacial retreat in the eastern Tibetan Plateau

Unraveling the dynamics and driving forces of abundant and rare bacteria in response to glacial retreat is essential for a deep understanding of their ecological and evolutionary processes. Here, we used Illumina sequencing datasets to investigate ecological abundance, successional dynamics, and the co-occurrence patterns of abundant and rare bacteria associated with different stages of soil development in the Hailuogou Glacier Chronosequence. Abundant taxa exhibited ubiquitous distribution and tight clustering, while rare taxa showed uneven distribution and loose clustering along the successional stages. Both abundant and rare subcommunities were driven by different factors during assembly: the interactions of biotic and edaphic factors were the main driving forces, although less important for rare taxa than for the abundant ones. In particular, the redundancy analysis and structural equation modeling showed that soil organic C, pH, and plant richness primarily affected abundant subcommunities, while soil N and pH were most influential for rare subcommunities. More importantly, variation partitioning showed that edaphic factors exhibited a slightly greater influence on both abundant (7.8%) and rare (4.5%) subcommunities compared to biotic factors. Both abundant and rare bacteria exhibited a more compact network topology at the middle than at the other chronosequence stages. The overlapping nodes mainly belonged to Proteobacteria and Acidobacteria in abundant taxa and Planctomycetia, Sphingobacteriia, and Phycisphaerae in rare taxa. In addition, the network analysis showed that the abundant taxa exhibited closer relationships and more influence on other co-occurrences in the community when compared to rare taxa. These findings collectively reveal divergent co-occurrence patterns and driving forces for abundant and rare subcommunities along a glacier forefield chronosequence in the eastern Tibetan Plateau.Peer reviewe

An Online Unified Delay and Slew Rate Regulation for Current Sharing in Paralleled SiC Power Modules With Active Gate Drivers

To ensure balanced current sharing between paralleled power modules, active gate drivers (AGDs) can be used to adjust the currents dynamically. However, achieving effective, flexible and accurate dynamic current adjustment is a challenge for AGDs under the very fast switching speed of silicon carbide (SiC) devices, e.g., <100 ns. Therefore, an online unified turn-ON/OFF delay and current slew rate regulation scheme for AGDs for paralleling SiC metal-oxide-semiconductor field-effect-transistor (MOSFET) power modules is proposed in this article. The advantage of the proposed scheme is that it achieves independent closed-loop control for the delay regulation and the current slew rate regulation, i.e., the adjustment of the current slew rate will not affect the already-tuned delay compensation. Also, the proposed AGD based on gate resistance adjustment with just two push–pull driver channels and less switching actions can achieve the wider-range and multilevel current slew rate regulation. Experimental validation of the closed-loop current regulation for current sharing between SiC power modules with the presented AGD is provided

Decoupled and Analytical Model of the Quad-Active-Bridge DC/DC Wind Converter under Transmitting Instantaneous Pulsating Power

The quad-active-bridge (QAB) DC/DC converter has shown superior advantages in eliminating the low-frequency voltage ripple in the cascaded wind power converter. However, the power flowing into the QAB converter contain low-frequency pulsation, causing low-frequency envelope oscillation issues inside the QAB converter. This paper proposes a decoupled and analytical model for quantitively analysis of the corresponding operation characteristics. Specifically, a summation difference transformation is proposed to decouple the multivariable coupling model as a diagonal decoupled model. The QAB converter voltages with time-varying angles are decomposed as the supervision of multiple frequency components by the Bessel function. Various characteristics such as input current stress (peak and rms), low-frequency envelope oscillations have been thoroughly analyzed under instantaneous pulsating power transmission with the proposed model. These results can be further used for designing more high-performance control strategies to optimize operation. Simulation and experimental results are presented to validate the proposed analytical model

State-of-the-Art in Carbides/Carbon Composites for Electromagnetic Wave Absorption

Electromagnetic wave absorbing materials (EWAMs) have made great progress in the past decades, and are playing an increasingly important role in radiation prevention and antiradar detection due to their essential attenuation toward incident EM wave. With the flourish of nanotechnology, the design of high-performance EWAMs is not just dependent on the intrinsic characteristics of single-component medium, but pays more attention to the synergistic effects from different components to generate rich loss mechanisms. Among various candidates, carbides and carbon materials are usually labeled with the features of chemical stability, low density, tunable dielectric property, and diversified morphology/microstructure, and thus the combination of carbides and carbon materials will be a promising way to acquire new EWAMs with good practical application prospects. In this review, we introduce EM loss mechanisms related to dielectric composites, and then highlight the state-of-the-art progress in carbides/carbon composites as high-performance EWAMs, including silicon carbide/carbon, MXene/carbon, molybdenum carbide/carbon, as well as some uncommon carbides/carbon composites and multicomponent composites. The critical information regarding composition optimization, structural engineering, performance reinforcement, and structure-function relationship are discussed in detail. In addition, some challenges and perspectives for the development of carbides/carbon composites are also proposed after comparing the performance of some representative composites

Flexural behaviour of damaged concrete T-beams reinforced with ultra-high performance concrete filling

To improve the flexural performance of damaged reinforced concrete T-beams, a method of filling ultra-high performance concrete (UHPC) in the damaged area was adopted. Experimental studies were conducted on two UHPC-reinforced concrete T-beams with different lengths of damaged areas and one undamaged concrete T-beam as a reference. Crack distribution, failure modes, cracking loads, flexural capacities, and strain variation of the specimens were analyzed. Subsequently, a nonlinear finite element (FE) model of the UHPC-reinforced T-beam was developed using ABAQUS, and the FE model results were compared with the experimental results to validate the accuracy of the FE simulation method. The results indicated that the two UHPC-reinforced T-beams exhibited a similar flexural failure process to the undamaged T-beam. The longitudinal tensile strain distribution at the mid-span section showed that the composite section formed by the filling of UHPC in the damaged region still adhered the assumption of the planar section. Owing to the excellent bond performance between UHPC and the existing concrete, the main cracks of the UHPC-reinforced T-beams appeared in the chiseled area, and the crack widths of the UHPC-reinforced T-beams under the same load were smaller than those of the reference T-beam. Overall, the reinforcing method of filling UHPC in the damaged region can restore or even enhance the flexural performance of the damaged reinforced concrete T-beams