Low-carbon generation expansion planning considering uncertainty of renewable energy at multi-time scales

With the development of carbon electricity,achieving a low-carbon economy has become a prevailing and inevitable trend.Improving low-carbon expansion generation planning is critical for carbon emission mitigation and a lowcarbon economy.In this paper,a two-layer low-carbon expansion generation planning approach considering the uncertainty of renewable energy at multiple time scales is proposed.First,renewable energy sequences considering the uncertainty in multiple time scales are generated based on the Copula function and the probability distribution of renewable energy.Second,a two-layer generation planning model considering carbon trading and carbon capture technology is established.Specifically,the upper layer model optimizes the investment decision considering the uncertainty at a monthly scale,and the lower layer one optimizes the scheduling considering the peak shaving at an hourly scale and the flexibility at a 15-minute scale.Finally,the results of different influence factors on low-carbon generation expansion planning are compared in a provincial power grid,which demonstrate the effectiveness of the proposed model.

Optimization operation model of electricity market considering renewable energy accommodation and flexibility requirement

The renewable portfolio standard has been promoted in parallel with the reform of the electricity market,and the flexibility requirement of the power system has rapidly increased.To promote renewable energy consumption and improve power system flexibility,a bi-level optimal operation model of the electricity market is proposed.A probabilistic model of the flexibility requirement is established,considering the correlation between wind power,photovoltaic power,and load.A bi-level optimization model is established for the multi-markets;the upper and lower models represent the intra-provincial market and inter-provincial market models,respectively.To efficiently solve the model,it is transformed into a mixed-integer linear programming model using the Karush–Kuhn–Tucker condition and Lagrangian duality theory.The economy and flexibility of the model are verified using a provincial power grid as an example.

Real-time scheduling strategy for microgrids considering operation interval division of DGs and batteries

Real-time scheduling as an on-line optimization process must output dispatch results in real time. However, the calculation time required and the economy have a trade-off relationship. In response to a real-time scheduling problem, this paper proposes a real-time scheduling strategy considering the operation interval division of distributed generators(DGs) and batteries in the microgrid. Rolling scheduling models, including day-ahead scheduling and hours-ahead scheduling, are established, where the latter considers the future state-of-charge deviations. For the real-time scheduling, the output powers of the DGs are divided into two intervals based on the ability to track the day-ahead and hours-ahead schedules. The day-ahead and hours-ahead scheduling ensure the economy, whereas the real-time scheduling overcomes the timeconsumption problem. Finally, a grid-connected microgrid example is studied, and the simulation results demonstrate the effectiveness of the proposed strategy in terms of economic and real-time requirements.

Experimental and Numerical Analysis of High-Strength Concrete Beams Including Steel Fibers and Large-Particle Recycled Coarse Aggregates

In order to study the performances of high-strength concrete beams including steel fibers and large-particle recycled aggregates,four different beams have been designed,tested experimentally and simulated numerically.As varying parameters,the replacement rates of recycled coarse aggregates and CFRP(carbon fiber reinforced polymer)sheets have been considered.The failure mode of these beams,related load deflection curves,stirrup strain and shear capacity have been determined through monotonic loading tests.The simulations have been conducted using the ABAQUS finite element software.The results show that the shear failure mode of recycled concrete beams is similar to that of ordinary concrete beams.The shear carrying capacity of high-strength concrete beams including steel fibers and large-particle recycled coarse aggregates grows with an increase in the replacement rate of recycled coarse aggregates.Reinforcement with CFRP sheets can significantly improve the beam’s shear carrying capacity and overall resistance to deformation.

Extreme temperature increases the severity of intracerebral hemorrhage: An analysis based on the cold region of China

Objective:The purpose of this study was to find a suitable model to evaluate the relationship between temperature and intracerebral hemorrhage(ICH)and explore the effects of cold spells and heat waves on the clinicopathological parameters of ICH patients.Methods:We conducted a retrospective study based on the ICH admission in the First Affiliated Hospital of Harbin Medical University from 2015 to 2020(N=11124).The relationship between different seasons and the number of patients with ICH was explored.Poisson Akaike information criterion(AIC)was used to select the optimal model for temperature and ICH.Binary logistic regression analysis was used to investigate the association between extreme temperatures and clinicopathological features.Results:Hospital admissions for patients with ICH showed monthly changes.The optimal cold spell was defined as the daily average temperature<3rd percentile,lasting for five days,while the optimal heat wave was defined as the daily average temperature>97th percentile,lasting for three days.Based on the generalized extreme weather model,cold climate significantly increased the risk of hematoma volume expansion(OR 1.003;95%CI:1.000-1.005,P=0.047).In the optimal model,the occurrence of cold spells and heat waves increased the risk of midline shift in both conditions(OR 1.067;95%CI:1.021-1.115,P=0.004;OR 1.077;95%CI:1.030-1.127,P=0.001).Conclusion:Our study shows that seasonal cold spells and heat waves are essential factors affecting ICH severity,and targeted preventive measures should be taken to minimize the pathological impacts.

Experimental Study on the Axial Compression Behavior of Short Columns of Steel-Fiber-Reinforced Recycled Aggregate Concrete

In order to study the axial compression performances of short columns made of recycled aggregate concrete,four samples were designed with different recycled aggregate replacement rates and carbon fibre reinforced plastics(CFRP)sheets.Then,monotonic loading was implemented to assess the variation trends of their axial compression properties.The ABAQUS finite element software was also used to determined the compression performances.Good agreement between experimental and numerical results has been found for the different parameters being considered.As shown by the results,recycled coarse aggregates result in improved ductility and better deformation performance of the specimens.The failure of specimens caused by pre damage can be compensated by using CFRP sheets,by which both the resistance to deformation and the axial carrying capacity of columns can be increased.

Understanding the role of miRNAs in the pathogenesis of brain arteriovenous malformations

Brain arteriovenous malformations(AVMs)are abnormal vessels that are prone to rupture,ausing life threatening intracerebral hemorrhage(ICH).Understanding the moleaular basis of pathogenesis,timely diagnosis,and treatment of brain AVMs are some of the urgent problems in neur osur gery.MiaoRNAs(miRNAs)are small endogenous RNAs that regulate gene-epression psttranscriptionally.MiRNAs are involved in almost all biological procsss,induding cell proliferation,apoptosis,and cell differentiation.Recent studies have shown that miRNAs an be involved in brain AVMs formation and rupture.There are also extracellular forms of miRNAs.Circulating miRNAs have been detected in the blood circulation and other body fluids.Owing to their stability and resistance to endogenous RNase activity,circulating miRNAs have been proposed as diagnostic and prognostic biomarkers for various diseases,such as tumors,cardiovascular and autoimmune diseases.In this review,we summarized the role of some miRNAs in brain AVMs pathogenesis and discussed their potential cdinical appliation as non-invasive biomarkers.

Distribution and characteristic of PAHs in snow of Fildes Peninsula

Polycyclic aromatic hydrocarbons (PAHs) investigation in different matrices has been reported largely,whereas reports on snow samples were limited.Snow,as the main matrix in the polar region,has an important study meaning.PAHs in snow samples were analyzed to investigate the distribution and contamination status of them in the Antarctic,as well as to provide some references for global migration of PAHs.Snow samples collected in Fildes Peninsula were enriched and separated by solid-phase membrane disks and eluted by methylene dichloride,then quantified by gas chromatography/mass spectrometry.All types of PAHs were detected except for Benzo(a)pyrene.Principal component analysis method was applied to characterize them.Three factors (Naphthalene,Fluorene and Phenanthrene) accounted for 60.57%,21.61% and 9.80%,respectively.The results showed that the major PAHs sources maybe the atmospheric transportation,and the combustion of fuel in Fildes Peninsula.The comparison of concentration and types of PAHs between accumulated snow and fresh snow showed that the main compound concentrations in accumulated snow samples were higher than those in fresh ones.The risk assessment indicated that the amount of PAHs in the snow samples would not lead to ecological risk.

Recent progress in ZnO-based heterojunction ultraviolet light-emitting devices

Wide bandgap(3.37 eV)and high excitonbinding energy of ZnO(60 meV)make it a promising candidate for ultraviolet light-emitting diodes(LEDs)and low-threshold lasing diodes(LDs).However,the difficulty in producing stable and reproducible high-quality p-type ZnO has hindered the development of ZnO p–n homojunction LEDs.An alternative strategy for achieving ZnO electroluminescence is to fabricate heterojunction devices by employing other available p-type materials(such as p-GaN)or building new device structures.In this article,we will briefly review the recent progress in ZnO LEDs/LDs based on p–n heterostructures and metal–insulatorsemiconductor heterostructures.Some methods to improve device efficiency are also introduced in detail,including the introduction of Ag localized surface plasmons and single-crystalline nanowires into ZnO LEDs/LDs.

Random lasing of CsPbBr3 perovskite thin films pumped by modulated electron beam

Aiming at the application requirements of information optics,this Letter proposed a perovskite quantum dot random lasing pumping method suitable for high-speed modulation.At the same time,the luminescence characteristics of perovskite quantum dot films under electron beam pumping conditions are analyzed,and the random lasing mechanism of electron beam pumping CsPbBr3 quantum dot films is revealed.Finally,it is confirmed that perovskite quantum dots are easy to realize random lasing under electron beam pumping conditions.