Assessment of Axial Power Peaking Factors in GHARR-1 LEU Core: A Decadal Simulation Analysis

This study aims to thoroughly investigate the axial power peaking factors (PPF) within the low-enriched uranium (LEU) core of the Ghana Research Reactor-1 (GHARR-1). This study uses advanced simulation tools, like the MCNPX code for analysing neutron behavior and the PARET/ANL code for understanding power variations, to get a clearer picture of the reactor’s performance. The analysis covers the initial six years of GHARR-1’s operation and includes projections for its whole 60-year lifespan. We closely observed the patterns of both the highest and average PPFs at 21 axial nodes, with measurements taken every ten years. The findings of this study reveal important patterns in power distribution within the core, which are essential for improving the safety regulations and fuel management techniques of the reactor. We provide a meticulous approach, extensive data, and an analysis of the findings, highlighting the significance of continuous monitoring and analysis for proactive management of nuclear reactors. The findings of this study not only enhance our comprehension of nuclear reactor safety but also carry significant ramifications for sustainable energy progress in Ghana and the wider global context. Nuclear engineering is essential in tackling global concerns, such as the demand for clean and dependable energy sources. Research on optimising nuclear reactors, particularly in terms of safety and efficiency, is crucial for the ongoing advancement and acceptance of nuclear energy.

Research on the Spatiotemporal Evolution,and Optimized Paths of Carbon Pressure in Northwestern Sichuan under the Carbon Peaking and Carbon Neutrality Goals

Consolidating carbon sink capacity and reducing carbon pressure are important channels to achieve the carbon peaking and carbon neutrality goals actively yet prudently.In order to study the current situation of carbon pressure in the Northwestern Sichuan,we took the carbon pressure of the Aba Tibetan-Qiang autonomous prefecture(Aba prefecture)as an example and used the Intergovernmental Panel on Climate Change(IPCC)approach to measure the carbon emissions,carbon uptake,and the carbon balance index(CBI)of each county-level city in Aba prefecture from 2012 to 2020.The study found that:(a)There was a continuous trend of declining carbon emissions,increased carbon uptake,and decreased CBI in Aba prefecture during the sample period,but there is a large variability among county-level cities;(b)Aba prefecture differs in the spatiotemporal distribution of carbon emissions,carbon uptake,and CBI.Based on the research results,we propose several optimized paths for alleviating the current carbon pressure situation in the Northwestern Sichuan.

Chopping-peaking开关形成高功率超宽带双极脉冲的实验研究

设计研制了一种chopping peaking组合开关型高功率双极脉冲形成装置,通过调节两个开关的导通时刻来得到不同形状的双极脉冲。理想情况下,形成的双极脉冲电压峰 峰值等于入射脉冲峰值电压的2倍,实验中入射脉冲峰值电压为205kV的单极脉冲,获得了最大峰 峰电压为360kV的双极脉冲,是入射脉冲峰值电压的1.76倍。双极脉冲的持续时间可以改变,最大值为单极脉冲的脉宽。入射脉冲上升时间越小,得到的双极脉冲峰 峰电压就越大。

Environmental Issues and Management for Hydropower Peaking Operations

Many hydropower plants are operated as peak generators or frequency controllers, because they can change their output quickly to follow the fluctuating power demand. When meeting peak load requirements, a power station is turned on at a particular time during the day, generates power at a constant load for a certain number of hours, and is then turned off or set to a different load for another time period, resulting in a high variability inflow discharges. Where reservoir hydro schemes are operated primarily to provide peak load services, there are particular environmental risks that should be considered in any environmental impact assessment. At a minimum these should focus on water quality, fluvial geomorphology, riparian vegetation, macro-invertebrate and fish communities underpinned by a sound hydrological analysis. Frequent temperature changes may occur downstream of a peaking power station; increased seepage-induced erosion of riverbanks due to frequent water level drawdowns; and impacts to macro-invertebrate and fish communities due to rapid and frequent in channel habitat conditions. With a sound understanding of the potential environmental issues, there are strategies that can be employed at the siting and design stage to minimize or mitigate these risks, including but not limited to minimum environmental flows, ramping rules, utilization of a re-regulation storage and localized treatment works.

Impact of E×B flow shear stabilization on particle confinement and density peaking at JET

The impact of the E×B flow shear stabilization on particle transport and density peaking at JET is analyzed in the framework of integrated modelling with the CRONOS code.For that purpose,plasmas from a power scan which show a significant increasing of density peaking with the injected neutral beam injection power have been used as a modeling basis.By means of simulations with the quasilinear model GLF23 for the heat and particle transport,a strong link between the particle confinement and E×B flow shear stabilization is found.This is particularly important close to the pedestal region where the particle pinch direction becomes strongly inward for high E×B flow shear values.Such impact introduces some non-negligible deviation from the well-known collisonality dependence of the density peaking,whose general trend has been also obtained in the framework of this modelling by performing pedestal density scans.

Improved Density Peaking Algorithm for Community Detection Based on Graph Representation Learning

There is a large amount of information in the network data that we canexploit. It is difficult for classical community detection algorithms to handle network data with sparse topology. Representation learning of network data is usually paired with clustering algorithms to solve the community detection problem.Meanwhile, there is always an unpredictable distribution of class clusters outputby graph representation learning. Therefore, we propose an improved densitypeak clustering algorithm (ILDPC) for the community detection problem, whichimproves the local density mechanism in the original algorithm and can betteraccommodate class clusters of different shapes. And we study the communitydetection in network data. The algorithm is paired with the benchmark modelGraph sample and aggregate (GraphSAGE) to show the adaptability of ILDPCfor community detection. The plotted decision diagram shows that the ILDPCalgorithm is more discriminative in selecting density peak points compared tothe original algorithm. Finally, the performance of K-means and other clusteringalgorithms on this benchmark model is compared, and the algorithm is proved tobe more suitable for community detection in sparse networks with the benchmarkmodel on the evaluation criterion F1-score. The sensitivity of the parameters ofthe ILDPC algorithm to the low-dimensional vector set output by the benchmarkmodel GraphSAGE is also analyzed.

Risks,Challenges and Countermeasures for China’s Power Industry to Cope with Carbon Peaking

The situation of China’s power industry to achieve carbon peaking and risks and challenges for China’s power industry to cope with carbon peaking were analyzed, and then macro countermeasures for the power industry to cope with carbon peaking were proposed.

Numerical Calculation of the Peaking Factor of a Water-Cooled W/Cu Monoblock for a Divertor

In order to accurately predict the incident critical heat flux（ICHF,the heat flux at the heated surface when CHF occurs） of a water-cooled W/Cu monoblock for a divertor,the exact knowledge of its peaking factors（f_p） under one-sided heating conditions with different design parameters is a key issue.In this paper,the heat conduction in the solid domain of a water-cooled W/Cu monoblock is calculated numerically by assuming the local heat transfer coefficients（HTC）of the cooling wall to be functions of the local wall temperature,so as to obtain f_p.The reliability of the calculation method is validated by an experimental example result,with the maximum error of 2.1% only.The effects of geometric and flow parameters on the f_p of a water-cooled W/Cu monoblock are investigated.Within the scope of this study,it is shown that the f_p increases with increasing dimensionless W/Cu monoblock width and armour thickness（the shortest distance between the heated surface and Cu layer）,and the maximum increases are 43.8% and 22.4% respectively.The dimensionless W/Cu monoblock height and Cu thickness have little effect on f_p.The increase of Reynolds number and Jakob number causes the increase of f_p,and the maximum increases are 6.8% and 9.6% respectively.Based on the calculated results,an empirical correlation on peaking factor is obtained via regression.These results provide a valuable reference for the thermal-hydraulic design of water-cooled divertors.

Study on the Carbon Effect of Agricultural Land Remediation Based on the Carbon Peaking and Carbon Neutrality Goals

With the goal of achieving carbon peak and carbon neutrality,this paper studies the carbon effect of agricultural land remediation.In this paper,the carbon effect mechanism and calculation method of land consolidation,the proposed national carbon peaking and carbon neutrality goals,and the requirements put forward by agricultural land consolidation followed were analyzed.Then,the application research on the carbon effect accounting of agricultural land consolidation was conducted.Besides,the application process of carbon effect accounting of land consolidation with the goals of carbon peaking and carbon neutrality.Therefore,we hope this study will play an effective role to advance the carbon effect research in the regulation of agricultural land.

Policy and Management of Carbon Peaking and Carbon Neutrality:A Literature Review

The vision of reaching a carbon peak and achieving carbon neutrality is guiding the low-carbon transition of China’s socioeconomic system.Currently,a research gap remains in the existing literature in terms of studies that systematically identify opportunities to achieve carbon neutrality.To address this gap,this study comprehensively collates and investigates 1105 published research studies regarding carbon peaking and carbon neutrality.In doing so,the principles of development in this area are quantitively analyzed from a space–time perspective.At the same time,this study traces shifts and alterations in research hotspots.This systematic review summarizes the priorities and standpoints of key industries on carbon peaking and carbon neutrality.Furthermore,with an emphasis on five key management science topics,the scientific concerns and strategic demands for these two carbon emission-reduction goals are clarified.The paper ends with theoretical insights on and practical countermeasures for actions,priority tasks,and policy measures that will enable China to achieve a carbon-neutral future.This study provides a complete picture of the research status on carbon peaking and carbon neutrality,as well as the research directions worth investigating in this field,which are crucial to the formulation of carbon peak and carbon neutrality policies.

An analysis of China's CO_2 emission peaking target and pathways

China has set the goal for its CO2 emissions to peak around 2030, which is not only a strategic decision coordinating domestic sustainable development and global climate change mitigation but also an overarching target and a key point of action for China＇s resource conservation, environmental protection, shift in economic development patterns, and CO2 emission reduction to avoid climate change. The development stage where China maps out the CO2 emission peak target is earlier than that of the developed countries. It is a necessity that the non-fossil energy supplies be able to meet all the increased energy demand for achieving CO2 emission peaking. Given that China＇s potential GDP annual increasing rate will be more than 4%, and China＇s total energy demand will continue to increase by approximately 1.0%--1.5% annually around 2030, new and renewable energies will need to increase by 6%-8% annually to meet the desired CO2 emission peak. The share of new and renewable energies in China＇s total primary energy supply will be approximately 20% by 2030. At that time, the energy consumption elasticity will decrease to around 0.3, and the annual decrease in the rate of CO2 intensity will also be higher than 4% to ensure the sustained growth of GDE To achieve the CO2 emission peaking target and substantially promote the low-carbon deve!opment transformation, China needs to actively promote an energy production and consumption revolution, the innovation of advanced energy technologies, the reform of the energy regulatory system and pricing mechanism, and especially the construction of a national carbon emission cap and trade system.

The economic impact of emission peaking control policies and China's sustainable development

To achieve the goals of national sustainable development, the peaking control of CO2 emissions is pivotal, as well as other pollutants. In this paper, we build a Chinese inter-regional CGE model and simulate 13 policies and their combinations. By analyzing the energy consumptions, coal consumptions, relating emissions and their impacts on GDP, we found that with the structure adjustment policy, the proportion of coal in primary fossil fuels in 2030 will decrease from 53% to 48% and CO2 emissions will decrease by 11.3%-22.8% compared to the baseline scenario. With the energy intensity reduction policy, CO2 emissions will decrease by 33.3% in 2030 and 47.8% in 2050 than baseline scenario. Other pollutants will also be controlled as synergetic effects. In this study we also find that although the earlier the peaking time the better for emission amounts control, the economic costs can not be ignored. The GDP will decrease by 2.96%-8.23% under different scenarios. Therefore, integrated policy solutions are needed for realizing the peaks package and more targeted measures are required to achieve the peaks of other pollutants earlier.

Multi-model comparison of CO2 emissions peaking in China:Lessons from CEMF01 study

The paper summarizes results of the China Energy Modeling Forum's(CEMF)first study.Carbon emissions peaking scenarios,consistent with China's Paris commitment,have been simulated with seven national and industry-level energy models and compared.The CO2 emission trends in the considered scenarios peak from 2015 to 2030 at the level of 9e11 Gt.Sector-level analysis suggests that total emissions pathways before 2030 will be determined mainly by dynamics of emissions in the electric power industry and transportation sector.Both sectors will experience significant increase in demand,but have low-carbon alternative options for development.Based on a side-by-side comparison of modeling input and results,conclusions have been drawn regarding the sources of emissions projections differences,which include data,views on economic perspectives,or models'structure and theoretical framework.Some suggestions have been made regarding energy models'development priorities for further research.

Thoughts on strategies and paths to achieve carbon peaking and carbon neutrality in China

First,a brief introduction is made to the four basic judgments and understandings of the goals of"carbon peaking and carbon neutrality."Then,an in-depth elaboration is provided on the eight major strategies for achieving the goals of"carbon peaking and carbon neutrality,"including conservation and efficiency priority,energy security,non-fossil energy substitution,reelectrification,resource recycling,carbon sequestration,digitalization and cooperation between countries.Next,eight major implementation paths for achieving the goals of"carbon peaking and carbon neutrality"are discussed in detail,including industrial restructuring;building a clean,low-carbon,safe and_efficient energy system,and renewing the understanding of China's energy resource endowment;accelerating the construction of a new-type power system with a gradually growing proportion of new energy,and realizing the"possible triangle"of highquality energy system development;utilizing electrification and deep decarbonization technologies to promote the orderly peaking and gradual neutralization of carbon emissions in the industrial sector;promoting the lowcarbon transition of transportation vehicles to achieve carbon peaking and carbon neutrality in the transportation sector;focusing on breaking through key green building technologies to achieve zero carbon emissions from building electricity and heat;providing a strong technical support for carbon removal to achieve carbon neutrality;accelerating the construction of the integrated planning and assessment mechanism for pollution and carbon reduction,establishing a sound strategy,planning,policy and action system,and optimizing the carbon trading system.Afterwards,it is particularly pointed out that the realization of the goals of"carbon peaking and carbon neutrality"cannot be separated from the support of scitech innovation.Finally,it is stressed that carbon neutrality is not the end,but an important milestone.If viewed from the perspective of future energy,the significance and historical status of the goals of"carbon peaking and carbon neutrality"will be more understandable.

Basic Path and System Construction of Green and Low-Carbon Agricultural Development with Respect to the Strategic Target of Carbon Peaking and Carbon Neutrality

The Dual Carbon strategy,which is aimed at achieving carbon peaking and carbon neutrality,is one of China's major strategiesinthecomingperiod.Agriculture is both an important source of greenhouse gas and a huge carbon sink system.To promote the Dual Carbon strategy,it is crucial for China to lay emphasis on green and low-carbon agricultural development.To achieve carbon peaking,agricultural carbonreduction and sequestration are significant means and haveegreat potential.Thisspaper firstly reviews the current situation of green and lowcarbon agricultural developmen.t.At present,the total agricultural carbon emissions in China are approaching the peak smoothly,and the proportion of carbon emissionsSgenerated by the use of such modern agricultural inputssas fertilizer and on-farm energy increases.Meanwhile,the operation of agricultural ecosystems in China demonstrates the strong capacity to absorb carbon.Then,the paper analyzes the main problems existing in green and low-carbon agricultural development,including excessive agricultural inputs and excessive consumption of fossil energy,the low utilization rate of agricultural resources,insufficient technical reserves for green and low-carbon agricultural development,and a weak supporting system.In the next part,the paper elaborates on the basic path and measures to realize green and low-carbon agriculturalddevelopment,such as strengthening the conservation of agricultural resources and improving the efficiency of resource utilization;enhancing the comprehensive treatment of agricultural non-point source pollution,realizing the reduction and efficiency of fertilizer and pesticide,resource utilization of agricultural wastes,and effective control of white agricultural pollution;cultivating,expanding and strengthening green and low-carbon agricultural industries,and greening the whole industrial chain of agricultural products from production,processing tocirculation;increasing scientific and technological innovation and building a scientific and technological support systems for green and low-carbon agricultural development.Finally,an institutional system to promote green and low-carbon agricultural development is constructed from the aspects of fiscal and taxation system,financial system,land management system,value realization mechanism of ecological products,and constraint and incentive mechanism,etc.This study provides a scientific basis for the further formulation of green and lowcarbon agricultural development policies and measures and relevant research.

Analysis of factors influencing carbon emissions in the Yangtze River Delta region and projections of carbon peak scenarios

Based on the supply-side perspective,the improved STIRPAT model is applied to reveal the mechanisms of supply-side factors such as human,capital,technology,industrial synergy,institutions and economic growth on carbon emissions in the Yangtze River Delta(YRD)through path analysis,and to forecast carbon emissions in the YRD from the baseline scenario,factor regulation scenario and integrated scenario to reach the peak.The results show that:(1)Jiangsu's high carbon emission pattern is the main reason for the YRD hindering the synergistic regulation of carbon emissions.(2)Human factors,institutional factors and economic growth factors can all contribute to carbon emissions in the YRD region,while technological and industrial factors can generally suppress carbon emissions in the YRD region.(3)Under the capital regulation scenario,the YRD region has the highest level of carbon emission synergy,with Jiangsu reaching its peak five years earlier.Under the balanced regulation scenario,the YRD region as a whole,Jiangsu,Zhejiang and Anhui reach the peak as scheduled.

顺倾及反倾层状碎裂结构斜坡地震反应的大型振动台试验研究

西南艰险山区分布着大量的不同倾向的层状碎裂结构斜坡,地震作用下极易发生崩塌、滑坡等灾害,对在建的川藏铁路造成严重威胁。通过大型振动台模型试验,研究了强震条件下顺倾、反倾层状碎裂结构斜坡的动力响应、失稳破坏模式以及能量传递规律。试验结果表明:反倾斜坡的抗震性能显著优于顺倾斜坡;顺倾斜坡的破坏模式主要为拉裂-剪切-隆起-滑移型破坏,反倾斜坡的破坏模式主要为拉伸-弯曲-倾倒-崩塌型破坏;反倾斜坡的自振频率高于顺倾斜坡,顺倾斜坡的自振频率随震级的增加而逐渐降低,而反倾斜坡的自振频率在地震波幅值为0.4g~0.7g时出现反复震荡现象;顺倾斜坡存在明显的高程放大效应和趋表效应,反倾斜坡存在高程放大效应,其内部的加速度响应大于坡表。边际谱识别显示:顺倾斜坡的边际谱幅值(peak of marginal spectrum amplitude,简称PMSA)突变在坡腰上部最显著,说明该位置附近地震波的能量损失最大,反映出顺倾斜坡在坡腰上部附近形成了滑动破坏面;反倾斜坡的PMSA在坡肩处降低得最为显著,反映出坡肩部位损伤最为严重,易发生局部崩塌破坏。分析结果与试验现象能够较好地吻合,进一步揭示了不同结构类型层状碎裂结构斜坡在强震作用下的动力响应与失稳破坏模式,为川藏铁路的安全建设提供了依据。

Safety and effectiveness of neuromuscular electrical stimulation in cardiac surgery:A systematic review

BACKGROUND Lack of mobilization and prolonged stay in the intensive care unit(ICU)are major factors resulting in the development of ICU-acquired muscle weakness(ICUAW).ICUAW is a type of skeletal muscle dysfunction and a common complication of patients after cardiac surgery,and may be a risk factor for prolonged duration of mechanical ventilation,associated with a higher risk of readmission and higher mortality.Early mobilization in the ICU after cardiac surgery has been found to be low with a significant trend to increase over ICU stay and is also associated with a reduced duration of mechanical ventilation and ICU length of stay.Neuromuscular electrical stimulation(NMES)is an alternative modality of exercise in patients with muscle weakness.A major advantage of NMES is that it can be applied even in sedated patients in the ICU,a fact that might enhance early mobilization in these patients.AIM To evaluate safety,feasibility and effectiveness of NMES on functional capacity and muscle strength in patients before and after cardiac surgery.METHODS We performed a search on Pubmed,Physiotherapy Evidence Database(PEDro),Embase and CINAHL databases,selecting papers published between December 2012 and April 2023 and identified published randomized controlled trials(RCTs)that included implementation of NMES in patients before after cardiac surgery.RCTs were assessed for methodological rigor and risk of bias via the PEDro.The primary outcomes were safety and functional capacity and the secondary outcomes were muscle strength and function.RESULTS Ten studies were included in our systematic review,resulting in 703 participants.Almost half of them performed NMES and the other half were included in the control group,treated with usual care.Nine studies investigated patients after cardiac surgery and 1 study before cardiac surgery.Functional capacity was assessed in 8 studies via 6MWT or other indices,and improved only in 1 study before and in 1 after cardiac surgery.Nine studies explored the effects of NMES on muscle strength and function and,most of them,found increase of muscle strength and improvement in muscle function after NMES.NMES was safe in all studies without any significant complication.CONCLUSION NMES is safe,feasible and has beneficial effects on muscle strength and function in patients after cardiac surgery,but has no significant effect on functional capacity.

Strategy of constructing virtual peaking unit by public buildings’central air conditioning loads for day-ahead power dispatching

With the gradually widely usage of the air conditioning(AC) loads in developing countries, the urban power grid load has swiftly increased over the past decade.Especially in China, the AC load has accounted for over30% of the maximum load in many cities during summer.This paper proposes a scheme of constructing a virtual peaking unit(VPU) by public buildings’ cool storage central AC(CSCAC) systems and non-CSCAC(NCSCAC)systems for the day-ahead power network dispatching(DAPND). Considering the accumulation effect of different meteorological parameters, a short term load forecasting method of public building’s central AC(CAC) baseline load is firstly discussed. Then, a second-order equivalent thermal parameters model is established for the public building’s CAC load. Moreover, the novel load reduction control strategies for the public building’s CSCAC system and the public building’s NCSCAC system are respectively presented. Furthermore, based on the multiple-rank control strategy, the model of the DAPND with the participation of a VPU is set up. The VPU is composed of large-scale regulated public building’s CAC loads. To demonstrate the effectiveness of the proposed strategy, results of a sample study on a region in Nanjing which involves 22 public buildings’ CAC loads are described in this paper. Simulated results show that, by adopting the proposed DAPND scheme, the power network peak load in the region obviously decreases with a small enough deviation between the regulated load value and the dispatching instruction of the VPU. The total electricity-saving amount accounts for7.78% of total electricity consumption of the VPU before regulation.

Active inductor shunt peaking in high-speed VCSEL driver design

An all-transistor active-inductor shunt-peaking structure has been used in a prototype of 8 Gbps high- speed VCSEL driver which is designed for the optical link in ATLAS liquid Argon calorimeter upgrade. The VCSEL driver is fabricated in a commercial 0.25 p^m Silicon-on-Sapphire （SOS） CMOS process for radiation tolerant purpose. The all-transistor active-inductor shunt-peaking is used to overcome the bandwidth limitation from the CMOS pro- cess. The peaking structure has the same peaking effect as the passive one, but takes a small area, does not need linear resistors and can overcome the process variation by adjust the peaking strength via an external control. The design has been taped out, and the prototype has been proven by the preliminary electrical test results and bit error ratio test results. The driver achieves 8 Gbps data rate as simulated with the peaking. We present the all-transistor active-inductor shunt-peaking structure, simulation and test results in this paper.