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Abstract The indirect‐to‐direct band‐gap transition in transition metal dichalcogenides (TMDCs) from bulk to monolayer, accompanying with other unique properties of two‐dimensional materials, has endowed them great potential in optoelectronic devices. The easy transferability and feasible epitaxial growth pave a promising way to further tune the optical properties by constructing van der Waals heterostructures. Here, we performed a systematic high‐throughput first‐principles study of electronic structure and optical properties of the layer‐by‐layer stacking TMDCs heterostructing superlattices, with the configuration space of [(MX2)n(M′X′2)10−n] (M/M′ = Cr, Mo, W; X/X′ = S, Se, Te; n = 0‐10). Our calculations involving long‐range dispersive interaction show that the indirect‐to‐direct band‐gap transition or even semiconductor‐to‐metal transition can be realized by changing component compositions of superlattices. Further analysis indicates that the indirect‐to‐direct band‐gap transition can be ascribed to the in‐plane strain induced by lattice mismatch. The semiconductor‐to‐metal transition may be attributed to the band offset among different components that is modified by the in‐plane strain. The superlattices with direct band‐gap show quite weak band‐gap optical transition because of the spacial separation of the electronic states involved. In general, the layers stacking‐order of superlattices results in a small up to 0.2 eV band gap fluctuation because of the built‐in potential. Our results provide useful guidance for engineering band structure and optical properties in TMDCs heterostructing superlattices.

With the gradual shift from dual control of energy consumption to dual control of carbon emissions, energy quota trading (EQT) and carbon emissions trading (CET) policies will be implemented in parallel in China. EQT policy will significantly affect the market performance and policy effects of CET, which consequently affects the dual control of carbon emissions. Therefore, constructing a system dynamics model coupling the national CET, EQT, and electricity markets, this paper researches the impact of EQT policy and its parameter design on the market performance and policy effects of CET through scenario analysis. The results show that: (1) Implementing EQT policy will reduce CET price and trading volume, negatively affecting CET market performance. This indicates that there is a certain substitution between EQT and CET. (2) EQT policy can enhance the emission reduction and decarbonization effects of CET policy. By curbing thermal power investment and generation and promoting green power, the EQT policy reduces carbon emissions by about 4.87% and optimizes the power supply structure. (3) To scientifically design the EQT policy parameters, lower energy saving targets and energy quota benchmark prices can alleviate the negative impact on CET market performance, but are not conducive to improving CET policy effects. [ABSTRACT FROM AUTHOR]

In this paper, a new robust adaptive control method has been proposed for nonlinear systems with uncertainties. This method combines the advantages of self-tuning control and sliding mode control. A simple parameterization model is first derived based on a linear dynamic model and unmodeled dynamics. Based on a modified sliding surface, the design procedure is based on the indirect adaptive control concept. This controller consists of four parts: 1) the system parameters estimation; 2) the unmodeled dynamics estimation; 3) the weighting polynomials updating; and 4) the control law calculation. The key merits of this controller are as follows: 1) the controller is applicable to non-minimum phase and open-loop unstable systems; 2) the estimation of the unmodeled dynamics is introduced as a feedback compensation control to improve the response; and 3) the strict stability condition is eliminated and a desirable performance is ensured during a wide operation region. Moreover, the control problem of a shape memory alloy actuator system is considered. In the literature, the mechanism model-based controllers have been extensively reported to address this issue. As an alternative, we describe this plant as a gray-box model. The adaptation algorithm and the control law have been implemented through the Beckhoff controller. The experimental results have demonstrated that the proposed controller has wider applicability than some existing methods.

Currently, the reform of electricity cross-subsidies on the sales side is a crucial task in the market-oriented process. The resulting electricity prices, which reflect the true value, can not only enhance resource allocation efficiency but also contribute to increased carbon emissions. Consequently, it is imperative to actively pursue carbon trading policies to address this issue. In this study, we examined the reformed electricity prices for industrial and residential users by applying the Ramsey pricing model. Moreover, a recursive dynamic computable general equilibrium model is employed to analyze the carbon emissions and economic performance of the cross-subsidy reform under different settings of the quota decline scheme, quota allocation mode, and penalty mechanism within the carbon emissions trading scheme. The results demonstrate the following findings: (1) The calculated Ramsey prices for industrial and residential users are 0.541 and 0.792 yuan/kWh, respectively. (2) Implementation of the electricity cross-subsidy reform can lead to a significant increment in CO2 emission. However, it effectively improves national economic and social development and promotes the growth of gross domestic product, industrial output, and changes in residential consumption expenditure structure. (3) Carbon trading proves to be an effective means to achieve carbon emission reduction at a lower economic cost after the reform. Notably, the degree of impact is more sensitive to the carbon decline factor. [ABSTRACT FROM AUTHOR]

Objective To explore the techniques and curative effect of microsurgical procedures assisted by minimal exposure tubular retractor system (METRx) in the treatment of lumbar disc herniation (LDH). Methods A total of 51 LDH patients, including 24 patients with L4-5 herniation and 27 patients with L5-S1 herniation, underwent discectomy assisted by METRx system. The operation time, intraoperative blood loss, postoperative complications and hospital stay were recorded. Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) were used to evaluate the degree of low back pain before operation, one week, 3 months after operation, and in the last follow-up. Lumbar MRI was used to evaluate the decompression of spinal canal. Results The success rate of operations in 51 cases was 98.04% (50/51). The average operation time was 125 min, the average intraoperative blood loss was 50 ml, the mean hospital stay was 5 d, all patients were followed up for 6-48 months (average 24 months). Compared with preoperation, both VAS and ODI scores decreased significantly one week after operation (P = 0.036, 0.029), 3 months after operation (P = 0.018, 0.023) and in the last follow-up (P = 0.007, 0.013). The improvement rate of ODI was 35.37% in the last follow-up. No infection, postoperative cerebrospinal fluid (CSF) fistula, neurological defects or incision infection was found. One patient presented acute abdominalgia on the 2nd day after operation, and was diagnosed as annexitis. One patient showed nerve root irritation symptoms after operation caused by thick nerve root during the surgery. They were cured after symptomatic treatment. Conclusions Microsurgical procedures for treating LDH assisted by METRx system can effectively relieve nerve root compression, protect the dural sac and nerve roots, and reduce surgical complications. DOI: 10.3969/j.issn.1672-6731.2016.04.008

A renewable portfolio standard is implemented to promote the development of renewable energy at a minimum cost through tradable green certificate market mechanism. Formulating a scientific and feasible renewable energy quota allocation scheme helps RPS function smoothly and optimize resource allocation. This paper proposed a bi-level programming model combined with entropy weight method to allocate renewable portfolio standard quotas with provincial heterogeneity and stakeholders' behavior, and an optimized quota allocation scheme among China's 30 provinces in 2020 was obtained. By comparing with the government's issued scheme, the following were the results under the optimized scheme: (1) Quotas in most provinces have increased, and the responsibility for renewable electricity generation is shared with the provinces with developed economy and well-constructed transmission facilities, where electricity producers can meet the quotas by purchasing tradable green certificate. (2) Quota allocation has positive effects on energy, economy, and environment. Specifically, the non-hydro renewable electricity generation increased by 43.8%, the non-hydro renewable electricity producers' profit increased by 18.4%, and the environmental pollution cost reduced by 27.9%. (3) Quota allocation equity measured by the environmental Gini coefficient increased by 14.3%. Based on these findings, some policy implications related to quota allocation and renewable portfolio standard's institutional arrangement have been put forward. [ABSTRACT FROM AUTHOR]