Noise-induced bistable switching dynamics through a potential energy landscape

Interlinked positive feedback loops,an important building block of biochemical systems,can induce bistable switching,leading to long-lasting state changes by brief stimuli.In this work,prevalent mutual activation between two species as another positive feedback is added to a generic interlinked positive-feedback-loop model originating from many realistic biological circuits.A stochastic fluctuation of the positive feedback strength is introduced in a bistable interval of the feedback strength,and bistability appears for the moderate feedback strength at a certain noise level.Stability analysis based on the potential energy landscape is further utilized to explore the noise-induced switching behavior of two stable steady states.

Energy Efficiency and Emissions Reduction Potential of China's Industrial Sector

Based on the total-factor energy efficiency framework,this paper calculates China's industrial energy efficiency and CO2 emissions reduction potential from 2000 to 2009 by utilizing the directional distance function and data envelopment analysis.The empirical results show that:China's industrial overall energy efficiency is relatively lower while the emis-sions reduction potential is relatively greater,given the optimum production frontier.Significant indus-trial disparities of energy efficiency and emissions reduction potential exist.Energy efficiency and emis-sions reduction potential significantly show different tendencies of industrial dynamic variation.This paper suggests the Chinese government impose differential carbon taxes,flexibly utilize carbon market mecha-nism,strengthen energy-saving technological R&D,promote the utilization of renewable energy,and strengthen environmental supervision and regulation,so as to improve China's industrial energy efficiency and reduce CO2 emissions.

Hybrid device for acoustic noise reduction and energy harvesting based on a silicon micro-perforated panel structure

A kind of hybrid device for acoustic noise reduction and vibration energy harvesting based on the silicon micro- perforated panel （MPP） resonant structure is investigated in the article. The critical parts of the device include MPP and energy harvesting membranes. They are all fabricated by means of silicon micro-electro-mechanical systems （MEMS） tech- nology. The silicon MPP has dense and accurate micro-holes. This noise reduction structure has the advantages of wide band and higher absorption coefficients. The vibration energy harvesting part is formed by square piezoelectric membranes arranged in rows. ZnO material is used as it has a good compatibility with the fabrication process. The MPP, piezo- electric membranes, and metal bracket are assembled into a hybrid device with multifunctions. The device exhibits good performances of acoustic noise absorption and acoustic-electric conversion. Its maximum open circuit voltage achieves 69.41 mV.

Automotive Interior Noise Reduction in High Frequency Using Statistical Energy Analysis

Statistical energy analysis (SEA) is an effective method for predicting high frequency vibro-acoustic performance of automobiles. A full vehicle SEA model is presented for interior noise reduction. It is composed of a number of subsystems based on a 3D model with all parameters for each subsystem. The excitation inputs are measured through road tests in different conditions,including inputs from the engine vibration and the sound pressure of the engine bay. The accuracy in high frequency of SEA model is validated,by comparing the analysis results with the testing pressure level data at driver's right ear. Noise contribution and sensitivity of key subsystems are analyzed. Finally,the effectiveness of noise reduction is verified. Based on the SEA model,an approach combining test and simulation is proposed for the noise vibration and harshness (NVH) design in vehicle development. It contains building the SEA model,testing for subsystem parameter identification,validating the simulation model,identifying subsystem power inputs,analyzing the design sensitivity. An example is given to demonstrate the interior noise reduction in high frequency.

Cooperative activation of sodium channels for downgrading the energy efficiency in neuronal information processing

The Hodgkin–Huxley model assumes independent ion channel activation,although mutual interactions are common in biological systems.This raises the problem why neurons would favor independent over cooperative channel activation.In this study,we evaluate how cooperative activation of sodium channels affects the neuron’s information processing and energy consumption.Simulations of the stochastic Hodgkin–Huxley model with cooperative activation of sodium channels show that,while cooperative activation enhances neuronal information processing capacity,it greatly increases the neuron’s energy consumption.As a result,cooperative activation of sodium channel degrades the energy efficiency for neuronal information processing.This discovery improves our understanding of the design principles for neural systems,and may provide insights into future designs of the neuromorphic computing devices as well as systematic understanding of pathological mechanisms for neural diseases.

纯电驱挖掘机动臂与斗杆复合能量回收系统

为改善液压挖掘机能效,提出一种纯电驱挖掘机的动臂与斗杆复合能量回收系统。采用液压蓄能器作为储能单元,回收动臂下降和斗杆内收过程中的重力势能;能量再生过程中,蓄能器释放高压油驱动与电动机同轴连接的变排量液压马达,辅助主电机驱动主泵,减少电动机能耗。分析所提系统工作原理,建立系统数学模型和多学科联合仿真模型,对采用所提系统的动臂和斗杆运行特性、重力势能回收效果和节能效果进行分析。结果表明:与传统电液流量匹配系统相比,动臂重力势能回收利用效率为62.1%,主电机能耗减少36.3%;斗杆重力势能回收效率为48.5%,主电机能耗减少22.1%。

Noise reduction effect of airfoil and small-scale rotor using serration trailing edge in a wind tunnel test

This paper discussed a noise reduction effect of airfoil and small-scale model rotor by using attached serration trailing edge in the wind tunnel test condition. In order to analyze the changes in the performance due to the inclusion of a serrated trailing edge designed to reduce noise, a 10 k W wind turbine rotor was equipped with a thin serrated trailing edge. The restrictive condition for the serrated trailing edge equipped with the using of a 2D airfoil was examined through the using of a wind tunnel experiment after studying existing restrictive condition and analyzing prior research on serrated trailing edges. The aerodynamic performance and noise reduction effect of a small-scale model were investigated with the using of a serrated trailing edge. Moreover, the noise levels from the experiment were considered that the noise prediction method could be used for a full-scale rotor. It is confirmed that noise reduction effect is compared with wind tunnel test data at the 2D airfoil and model rotor condition.

新能源汽车碳减排潜力分析

在“碳达峰、碳中和”双碳目标驱动下,新能源汽车凭借其碳减排优势受到了广泛关注.旨在促进新能源汽车碳减排潜力评估的相关研究,从新能源汽车碳排放计量与分析、车网协同优化低碳运行、车辆碳排放总量态势预测等三个方面进行分析与综述,归纳了相关领域最新研究成果,总结各类建模方法优缺点,重点阐述了汽车节能减排核算体系与行业碳排放管理体系等相关成果,并提出新能源汽车碳减排潜力分析研究的发展趋势及未来研究方向.

船舶空调通风系统风管漏风量标准分析

鉴于目前船舶空调通风领域还没有一个统一的限制风管漏风量的标准,通过分析研究船舶行业常用的EUROVENT 2/2标准,并比较了GB 50243—2016、DW144和SMACNA等相关标准,对于在船舶设计、建造过程中对于空调通风系统的漏风量提出了适合我国船舶空调通风系统风管漏风量标准的建议,在设计施工过程中可采取相应手段优化和减少风管漏风量的问题,供船舶设计人员参考。

气垫船壁板隔声性能分析与测试研究

气垫船对于噪声传递路径控制中的隔声控制,除了常规的隔声性能应满足相应要求外,还应保证其抗爆抗冲击等性能。本文对气垫船舱壁的前端抗冲击壁板进行隔声性能进行计算分析与实验测试。基于统计能量分析方法,采用双声腔-单板模型模拟驻波管设备,计算并结合实验测试验证了单层均质钢板的隔声量。为进一步验证统计能量分析方法预测材料隔声量的正确性,利用驻波管进行构件隔声量的实验研究,实验测量与统计能量分析预测结果在630 Hz以下的中低频段吻合良好,高频段随着吻合效应的出现,误差增大。结果表明,采用的统计能量分析模拟计算方法有效,该类型隔声构件的平均隔声量为44 dB,可有效降低目标舱室的噪声。本文的研究结果对气垫船及相类似舰船的减振降噪提供了新的思路。

低碳综合能源系统研究框架与关键问题研究综述

低碳综合能源系统是融合多种低碳技术和措施、集成灵活性资源、促进清洁能源消纳、降低碳排放的多能源系统,是实现“双碳”目标的物理载体。首先,从能源转型的宏观战略、物理载体和低碳技术角度论证了低碳综合能源系统是能源转型的有效路径,归纳了低碳综合能源系统的定义与特征内涵;然后,构建了低碳综合能源系统的研究框架,从源-网-荷-储及碳捕集等环节挖掘了低碳综合能源系统的减排潜力;为了充分发挥低碳综合能源系统的低碳优势,从协同规划与优化调度、市场机制等角度提炼了低碳综合能源系统的几个关键问题;最后,聚焦提炼的协同优化关键问题,从研究现状、面临问题和研究展望等方面进行了阐述,以期为能源系统的低碳发展提供参考。

珠三角城市群屋顶分布式光伏发电的综合潜力研究

屋顶光伏发电仅利用屋顶空间和太阳辐射,不额外占用土地资源,因此成为推动绿色能源转型的重要选择。珠江三角洲(珠三角)城市群是我国城市化进程最快的地区之一。本研究基于区域地理和当前技术条件提出5°和20°两种安装角度、单晶硅和多晶硅两种光伏板材料,共计4种屋顶光伏安装方案,分析在珠三角城市群开展大面积屋顶光伏项目的技术、经济以及减排潜力。结果显示,珠三角地区的城市屋顶总面积为2493.255 km^(2),占珠三角土地面积的4.5%;珠三角地区的最大屋顶光伏发电潜力约为440.6×10^(8)~721.2×10^(8) kW h,且每年能够减少47.83%~78.14%的广东省电力部门温室气体排放;通过净现值指标对屋顶光伏发电的经济收益进行评估,5°单晶硅的安装方案所带来净现值最高,达到了2151亿元,同时其初始投资也是4种安装模式中最小的;4种安装方案均在第四年可实现成本回收,表明在珠三角地区推行大面积屋顶光伏具有显著的潜力,未来屋顶光伏发电项目具有较强的投资吸引力。

基于企业聚类的某省化纤行业节能减碳潜力分析

化纤行业在“双碳”战略目标下面临着巨大的节能减碳压力,需要分析行业的能耗现状与节能减碳潜力。以中国化纤行业第一大省的146家化纤企业为研究对象,利用企业能耗数据分析行业的能耗特征,基于聚类算法对企业进行分类并计算行业的节能减碳潜力。结果表明,该省2013—2021年化纤行业的能耗结构和碳排放结构均以电力贡献为主,节能潜力占行业能耗量的24.63%,减碳潜力占行业碳排放量的22.91%。大型企业和能耗强度偏高的小型企业节能减碳建议以减少原煤消耗为主,中小型企业节能减碳建议以减少电力消耗为主。

中国能源消费差异化碳减排潜能分析

科学降低碳排放、杜绝“运动式减碳”等,已成为共建低碳社会的关键所在。本研究从切实促进碳减排、助力早日实现碳中和的角度出发,通过收集整理各省在“十一五”到“十三五”期间的能源消费数据,结合全国不透水面遥感监测数据等,对近15年我国能源消费及其碳排放的时空演变特征等进行分析,并利用所提出的碳排放水平评估指数(carbon emission level estimation,CELE),开展省域能源消费的碳减排潜能分析。结果显示,青海、山西、云南、甘肃和宁夏一直处于CELE高值区,黑龙江、吉林、天津、安徽和江西省一直处于CELE低值区,山东、福建、广西、海南的CELE指数则呈逐年递增状态,而吉林、湖南、重庆、贵州的CELE指数呈逐年递减状态。综合各省能源消耗及其碳排放现状和时空演变规律,以及CELE指数的测度结果可知,目前急需减排的省份主要包括山西、山东和广东,其次是辽宁、湖北和新疆;贵州、内蒙古在“十二五”期间碳减排成效显著,目前处于中等压力区;青海、甘肃、宁夏和云南因为人口数和建设用地均较少等,导致其CELE指数以及人均碳排放和地均碳排放都明显高于其他省份,对于它们的能源消费碳减排问题也需予以密切关注。

一种节能降噪的液压阀性能检测试验台液压系统

为解决液压阀性能检测试验台液压系统因溢流和节流产生的发热严重、噪音大等问题,提出将伺服电机和定量泵的组合作为液压阀试验台的液压源,通过检测液压阀的输出流量来控制电机转速。通过控制每个时间点的液压泵输出流量略大于液压阀测试所需流量来保证溢流阀的溢流作用。仿真和试验结果表明,液压阀测试液压系统可在保证正常工作的基础上实现节能和降噪,效果分别为33.6%和12.0%。研究成果可为液压试验台设计提供一定参考。

声学黑洞铝型材板结构减振特性仿真研究

声学黑洞(Acoustic Black Hole,ABH)技术作为一种新型高效的能量聚焦以及振动控制技术,在减振降噪方面具有很好应用潜力。铝型材板结构作为一种夹层结构,具有高比刚度和高比强度等优异轻量化特性,广泛应用于列车外地板、船舶、航空航天等领域中。为了探究ABH和铝型材板结构相结合后是否还具有典型的ABH效应,运用有限元数值模拟方法研究嵌入式ABH铝型材板结构的振动能量聚焦特性。对于频点和频带聚焦特性分析结果表明,在铝型材板结构中嵌入ABH特征结构可以起到显著振动能量聚焦效果。此外,根据聚焦特性分析结果,在ABH铝型材板结构中的ABH特定区域内敷设阻尼材料,并通过仿真计算验证了其减振特性。结果表明,由ABH铝型材板结构附加阻尼材料所得的组合结构振动水平显著低于普通铝型材板结构,部分频率下振动衰减高达52.6 dB。这为轨道交通领域提供了一种很有应用潜力的结构减振降噪新思路。

北京市办公建筑空调系统现状调研及节能改造潜力分析

通过对北京市71个政府办公建筑空调系统调研,分析空调系统能耗状况、用能设备现状、存在的问题及改造需求,提出空调系统节能改造技术路线。在此基础上,分析空调系统节能改造节能量、碳减排量和总投资,为空调系统节能改造方案制订提供指引。

供热通风与空调工程关键安装技术分析

作为建筑工程的一部分,供热通风空调工程又称暖通空调工程,其安装和施工质量直接影响到人民群众的生产生活。供热通风空调的安装是一项非常重要的工作,不仅能够改善建筑物的内部环境,还能够保证建筑物的安全。因此,施工企业应该特别注意这一方面的质量,并且严格遵守相关的行业标准,以确保安装的完整性和可靠性。供热通风与空调工程的核心特点之一便是其复杂的技术要求,在实施过程中,必须解决各种关键的技术难题,以确保其质量。基于此,该文主要围绕供热通风与空调工程关键安装技术展开分析,并提出具体的技术措施,以供参考。

特高压交直流输电线路带电作业安全防护及碳减排效应分析

特高压(ultra high voltage,UHV)交流与直流线路同廊道运行时带电作业区域电压高、场强大,交直流混合电场比单一电场更为复杂。为确保作业人员安全,结合实际±1100 kV直流和1000 kV交流线路,建立了包含输电导线、杆塔及带电作业人员的三维计算模型,通过分析开展带电作业时人员的体表混合场强、电位转移电流及暂态能量,对作业人员安全防护进行研究。结果表明:随着作业人员不断接近直流线路,体表场强受交流线路影响越明显,最高可使作业人员体表场强增大约9%,达到1920 kV/m;交流线路的存在将导致电位转移电流增长约7%,但对暂态能量影响较小。通过对特高压线路不停电检修所减少的碳排放量进行进一步计算,验证了特高压带电作业对减少碳排放具有促进作用。

Offshore wind power in China:A potential solution to electricity transformation and carbon neutrality

China is likely to lead global offshore wind power development,in the hope of transforming the coal-based electricity system and reducing greenhouse gas emissions.However,the potential of power generation and emissions mitigation is largely unknown,and the contribution of offshore wind utilization to regional carbon neutrality needs to be further clarified.Here,we reveal that offshore wind energy resources are abundant in China,with an estimated power generation potential of about 17.5 PWh,more than doubling the current power consumption nationwide.Although current utilization of offshore wind energy in China accounts for 21%of global overall capacity,the total share is still limited,supplying just 0.4%of national electricity needs(2019).With the increasing use of offshore wind,by 2050,the planned installation along China coast would be nearly five times as much as current(2019)global capacity,or 25 times of current national offshore wind power generation.The total CO_(2)emissions reduction in 2050 due to the decrease in coal use is projected to be 294.3 Tg CO_(2)-eq yr^(-1),equivalent to 20%of current emissions from coal-fired power in the coastal region.The size of reduced emissions is higher than current CO_(2)emissions in about 90%of countries.Our results highlight the important role of offshore wind power in upgrading the energy system and achieving carbon neutrality.Future studies are encouraged to further explore technological,economic and institutional challenges facing offshore wind energy deployment and low-carbon energy system development.