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Boosting daytime radiative cooling performance with nanoporous polyethylene film

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Energy and Built Environment

Energy and Built Environment 2023年第2期4卷 131-139页

作者： Junwei Liu Huajie Tang Ji zhang debao zhang Shifei Jiao Zhihua Zhou Tianjin Key Laboratory of Indoor Air Environmental Quality Control School of Environmental Science and EngineeringTianjin UniversityTianjin 300350China China Academy of Building Research Beijing 100013China China IPPR International Engineering Co. LtdBeijing 100089China

Radiative cooling without energy consumption and environmental pollution holds great promise as the next-generation cooling technology.To date,daytime radiative cooling performance is still slightly low,especially in humid areas.In this work,we demonstrated that nanoporous polyethylene(Nano PE)film can improve solar reflectivity from 96%to 99%,thus boosting radiative cooling performance.Moreover,the experimental results in humid areas indicate that Nano PE films can improve radiative cooling performance by∼76%in a clear day and 120%in a day with few clouds.Additionally,compared with ordinary PE films,thin Nano PE films have significantly higher weather fastness and mechanical strength.More importantly,nano PE films can scatter part of visible light,thus suppressing the generation of light pollution in practical applications.Lastly,the modeling results reveal that with Nano PE films,more than 95%of China’s areas can achieve daytime cooling performance.Our work can boost the development of radiative cooling technology with a very low cost.

关键词： Daytime radiative cooling Nano PE films Solar reflectivity Radiative cooling performance

Evaluation of in situ spoilage ability of common facultative anaerobic bacteria and confirmation of volatile spoilage markers in vacuum-packaged lamb

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Food Science and Human Wellness 2024年

作者： Xiangyuan Wen Dequan zhang Su Wang Zhiyuan Xiao Xin Li debao Wang Wei Yang Chengjun Min Chengli Hou Institute of Food Science and Technology Chinese Academy of Agricultural Sciences Key Laboratory of Agro-Products Quality and Safety Control in Storage and Transport Process Ministry of Agriculture and Rural Affairs Institute of Agricultural Product Processing and Nutritional Health Chinese Academy of Agricultural Sciences (Cangzhou) Sunrise Material Co. Ltd Jiangyin Beijing Ershang Meat Food Group Co. Ltd

Microbial growth causes lamb spoilage. This study explored the spoilage ability of Latilactobacillus sakei (L. sakei)， Serratia proteamaculans (S. proteamaculans) and Hafnia proteus (H. proteus) in vacuum-packed raw lamb， including growth ability， degradation of protein and lipid， and change of volatile organic compounds (VOCs) profile， meanwhile screened the key VOCs produced by the targeted strains with meat background excluding， finally confirmed the volatile spoilage marker of vacuum-packaged lamb by comparing with our previous work. The results showed that L. sakei， S. proteamaculans and H. proteus had excellent growth ability. L. sakei inoculated group significantly reduced the pH value， showed higher TCA-soluble peptides content， and excellently degraded sarcoplasmic and myofibrillar proteins. About free amino acids， L. sakei significantly degraded serine， arginine and aspartic acid， while S. proteamaculans and H. proteus significantly degraded serine and lysine. In addition， L. sakei had a strongest effect on promoting free fatty acids production， followed by S. proteamaculans and finally H. proteus. Evaluating from various indicators， the co-culture of the three strains did not have any effect. The key volatiles produced by L. sakei were 1-hexanol， acetic acid and hexanoic aicd， S. proteamaculans were 1-hexanol and acetoin， and H. proteus was 1-hexanol， acetic acid and acetoin. In the end， 1-hexanol， hexanoic acid and acetoin were proven to be spoilage markers for vacuum-packaged and chilled lamb. This study can provide fundamental information for inhibiting and rapid identification of spoilage in vacuum-packaged lamb.

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Sr_(2)LuNbO_(6):Mn^(4+)深红荧光粉的光学性质:晶体场劈裂和多模振动耦合

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Science China Materials 2024年第3期67卷 939-945页

作者：周广涵张德保唐飞郑昌成宁吉强徐士杰 Department of Optical Science and Engineering School of Information Science and TechnologyFudan UniversityShanghai 200438China School of Physics and Electronic Engineering Jiangsu Normal UniversityXuzhou 221116China Division of Natural and Applied Sciences Duke Kunshan UniversityKunshan 215316China

本研究利用光致发光(PL)、光致发光激发(PLE)、时间分辨PL和拉曼光谱技术等,详细研究了通过熔盐固相法合成的Sr_(2)LuNbO_(6):Mn^(4+)深红荧光粉的光学性质.在室温下,样品的PL光谱呈现出阶梯状谱形.然而,在低温下,测量的PL光谱由两组多... 详细信息

本研究利用光致发光(PL)、光致发光激发(PLE)、时间分辨PL和拉曼光谱技术等,详细研究了通过熔盐固相法合成的Sr_(2)LuNbO_(6):Mn^(4+)深红荧光粉的光学性质.在室温下,样品的PL光谱呈现出阶梯状谱形.然而,在低温下,测量的PL光谱由两组多模振动电子发光谱线组成.基于变温PL光谱和拉曼光谱,我们识别出双零声子谱线以及两组恒定能量间隔为~2.8 meV的多模声子伴线.这项研究首次发现Mn^(4+)离子的^(2)E_(g)激发态能级在氧化物八面体晶格中具有~2.8 meV能量差的劈裂,并证实多种振动模式深度参与Mn^(4+)离子的振动电子发光.

关键词： oxide phosphor deep red luminescence Mn^(4+)ion excited-state splitting impurity-lattice coupling

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聚脲涂覆大型钢制储罐抗冲击性能数值仿真

哈尔滨工业大学学报 2024年第6期56卷 44-51页

作者：张博一蒋月新翟德保王伟结构工程灾变与控制教育部重点实验室(哈尔滨工业大学) 哈尔滨150090 苏州科技大学土木工程学院江苏苏州215009 渤海造船厂集团有限公司辽宁葫芦岛125000

为提高大型钢制储罐抗冲击性能,开展聚脲涂覆大型钢制储罐冲击响应的数值模拟和理论分析研究。基于前期工作已验证的数值模型,建立聚脲涂覆钢罐的有限元模型。数值模拟结果表明:将聚脲涂覆于罐体外表面能有效降低冲击载荷作用下局部塑... 详细信息

为提高大型钢制储罐抗冲击性能,开展聚脲涂覆大型钢制储罐冲击响应的数值模拟和理论分析研究。基于前期工作已验证的数值模型,建立聚脲涂覆钢罐的有限元模型。数值模拟结果表明:将聚脲涂覆于罐体外表面能有效降低冲击载荷作用下局部塑性变形,在冲击体撞击角度为45°时能避免罐体穿孔破坏;聚脲涂层的主要防护机制为降速和垫层作用;提高喷聚脲涂厚度能增加罐体最大吸能值和面密度吸能值;当涂层厚度为15 mm时罐体不产生穿透破坏,满足英国储罐设计规范要求。根据罐体冲击响应特征和聚脲涂层作用机制,建立预测罐体断裂临界冲击速度的理论公式,能较精确预测涂覆罐的最大吸能值,可为聚脲涂覆钢制储罐抗冲击防护设计提供科学参考依据。

关键词：钢制储罐冲击聚脲数值模拟预测公式

Decentralized output-feedback control of triangular large-scale nonlinear impulsive systems with time-varying delays: a gain scaling approach

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Science China(Information Sciences) 2023年第11期66卷 185-203页

作者： debao FAN Xianfu zhang Weihao PAN Hanfeng LI School of Control Science and Engineering Shandong University

In this study, we investigate the decentralized output-feedback control problem for a class of triangular large-scale nonlinear impulsive systems(TLSNISs) with time-varying delays. Unlike existing design approaches in impulsive systems, a gain scaling approach is proposed for the first time to counteract the structural uncertainties of interconnected nonlinearities. Specifically, by fully exploiting the static gain, novel delay-independent impulsive observers are delicately constructed to estimate the unavailable states. Furthermore, the undesirable effects of time-varying delays and impulsive disturbances are eliminated using the comparison principle and average impulsive interval technique. The designed gain-scaling-based decentralized output-feedback controllers have concise linear-like forms and are independent of time delays. Moreover,by strengthening the gain scaling mechanism, we further develop an improved control scheme that endows the controllers with the capability to tolerate unknown external disturbances, thus improving its robustness.It is shown that the system states converge exponentially to the origin in the disturbance-free case with the designed controllers(or to an adjustable neighborhood of the origin in the presence of disturbance). Finally,two examples, including an engineering system design example, are provided to demonstrate the effectiveness of the designed controllers for both lower TLSNISs and upper TLSNISs.

关键词： triangular large-scale systems nonlinear impulsive systems time-varying delay output feedback gain scaling approach

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密度分层介质中水下航行体绕流涡演化特性

实验流体力学 2024年第2期38卷 31-39页

作者：张彬周根水高德宝杜欣明樊晓冰刘建华中国船舶科学研究中心深海技术科学太湖实验室无锡214082 天津大学机械工程学院天津300072

在真实海洋环境中,海水存在密度分层。当水下航行体在密度分层界面附近航行时,其尾流会破坏初始密度分层界面,形成分层尾迹。分层尾迹是非声目标特征之一,分层尾迹探测已成为水下航行体探测的新兴技术。为建立分层环境水下航行体尾迹探... 详细信息

在真实海洋环境中,海水存在密度分层。当水下航行体在密度分层界面附近航行时,其尾流会破坏初始密度分层界面,形成分层尾迹。分层尾迹是非声目标特征之一,分层尾迹探测已成为水下航行体探测的新兴技术。为建立分层环境水下航行体尾迹探测的理论基础和方法,应先探明水下航行体绕流涡系在密度分层介质中的发展演化特性。本文以缩比SUBOFF模型为研究对象,开展了实验测试和大涡模拟,得到了水下航行体绕流涡系在密度分层介质中的精细流场,大涡模拟和实验测试结果与相关文献测试结果基本吻合。研究发现:由于模型尾部分离涡存在强非定常性,尾流中盐水与淡水的掺混表现出多尺度特征;较强的孤立涡结构在掺混分层流体的过程中,逐渐演化为规则结构并脱离分层主界面,分层界面在一定宽度范围内整体呈现出离散特征。研究表明,基于密度梯度的尾迹探测手段可以对水下航行体尾流场进行有效探测。

关键词：水下航行体密度分层尾流大涡模拟粒子图像测速涡 SUBOFF模型

Global practical tracking via disturbance rejection control for uncertain nonlinear systems with quantized input and output

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Science China(Information Sciences) 2022年第1期65卷 279-281页

作者： debao FAN Xianfu zhang Yanjie CHANG Xiaodong LU School of Control Science and Engineering Shandong University School of Mathematics and Statistics Shandong Normal University

Dear editor,With the rapid development of digital control systems and other fields, quantized control has attracted increasing attention [1]. Although considerable research has been conducted on the analysis of quantized control systems, most of the theoretical results are based on a single quantizer. In real life, when the distance between devices and controllers is relatively remote,

关键词： FEEDBACK CONTROL

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手机成瘾动力学模型的定性分析

通化师范学院学报 2024年第2期45卷 40-45页

作者：高德宝张桢邱嘉仁黑龙江八一农垦大学理学院黑龙江大庆163319

根据手机用户不同群体之间的人员转移关系,文章构建了一个手机成瘾动力学模型.首先,计算了模型的基本再生数和两个平衡点.其次,证明了在一定条件下,非负平衡点和唯一正平衡点是全局渐近稳定的.最后,用数值算例验证了相关结论的正确性.

关键词：手机成瘾动力学模型平衡点全局稳定性数值仿真

Influencing Factors and Clustering Characteristics of COVID-19:A Global Analysis

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Big Data Mining and Analytics 2022年第4期5卷 318-338页

作者： Tianlong Zheng Chunli zhang Yueting Shi debao Chen Sheng Liu School of Computer Science and Technology Huaibei Normal UniversityHuaibei 235000China School of Economics and Management Tiangong UniversityTianjin 300000China

The unprecedented coronavirus disease 2019(COVID-19)pandemic is still raging(in year 2021)in many countries worldwide.Various response strategies to study the characteristics and distributions of the virus in various regions of the world have been developed to assist in the prevention and control of this epidemic.Descriptive statistics and regression analysis on COVID-19 data from different countries were conducted in this study to compare and evaluate various regression models.Results showed that the extreme random forest regression(ERFR)model had the best performance,and factors such as population density,ozone,median age,life expectancy,and Human Development Index(HDI)were relatively influential on the spread and diffusion of COVID-19 in the ERFR model.In addition,the epidemic clustering characteristics were analyzed through the spectral clustering algorithm.The visualization results of spectral clustering showed that the geographical distribution of global COVID-19 pandemic spread formation was highly clustered,and its clustering characteristics and influencing factors also exhibited some consistency in distribution.This study aims to deepen the understanding of the international community regarding the global COVID-19 pandemic to develop measures for countries worldwide to mitigate potential large-scale outbreaks and improve the ability to respond to such public health emergencies.

关键词： data analysis extreme random forest regression spectral clustering HDI COVID-19