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Thermodynamic Analysis of Packed Bed Thermal Energy Storage System

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Journal of Thermal Science 2020年第2期29卷 445-456页

作者： GUO Huan XU Yujie GUO Cong CHEN Haisheng WANG Yifei YANG Zheng HUANG Ye DOU Binlin Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China School of the Built Environment University of UlsterCo.Antrim BT370QBUK School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China

A packed-bed thermal energy storage(PBTES) device, which is simultaneously restricted by thermal storage capacity and outlet temperatures of both cold and hot heat transfer fluids, is characterized by an unstable operation condition, and its calculation is complicated. To solve this problem, a steady thermodynamics model of PBTES with fixed temperatures on both ends was built. By using this model, the exergy destruction, thermocline thickness, thermal storage capacity, thermal storage time, and other key parameters can be calculated in a simple way. In addition, the model explained the internal reason for the change of thermocline thickness during thermal storage and release processes. Furthermore, the stable operation of the PBTES device was analyzed, and it was found that higher inlet temperature of hot air, and lower temperature difference between cold and hot air can produce less exergy destruction and achieve a larger cycle number of stable operation. The work can be employed as the basis of the design and engineering application of PBTES.

关键词： packed bed thermal energy storage thermocline steady thermodynamic analysis stable operation

Local and regional contributions to PM_(2.5) in the Beijing 2022 Winter Olympics infrastructure areas during haze episodes

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Frontiers of Environmental Science & Engineering 2021年第6期15卷 499-509页

作者： Yue Wang Mengshuang Shi Zhaofeng Lv Huan Liu Kebin He State Key Joint Laboratory of ESPC State Environmental Protection Key Laboratory of Sources and Control of Air Pollution ComplexInternational Joint Laboratory on Low Carbon Clean Energy InnovationSchool of the EnvironmentTsinghua UniversityBeijing 100084China

The 2022 Winter Olympics is scheduled to take place in Beijing and Zhangjiakou,which were defined as OIAs(Olympic infirastructure areas)in this *** study presents the characteristics and source apportionment of PM_(2.5) in the OIAs,*** entire region of China's Mainland,except for the OIAs,was divided into 9 source regions,including four regions in the BTH(Beijing-Tianjin-Hebei)region,the four provinces surrounding the BTH and the remaining *** CAMx/PSAT,the contributions of the nine regions to the PM_(2.5) concentration in the OIAs were simulated spatially and *** simulated source apportionment results showed that the contribution of regional transportation was 48.78%,and when PM_(2.5) concentration was larger than 75μg/m^(3) central Hebei was the largest contributor with a contribution of 19.18%,followed by Tianjin,northern Hebei,Shanxi,Inner Mongolia,Shandong,southern Hebei,Henan and ***,the contribution from neighboring regions of the OIAs was 47.12%,which was nearly twice that of long-range *** episodes were analyzed,and the results presented the importance of regional transportation during severe PM_(2.5) pollution *** was also found that they were associated with differences in pollution sources between Zhangjiakou and *** transportation was the main factor affecting PM_(2.5) pollution in Zhangjiakou due to its low local *** weather with a low planetary boundary layer height and a low wind velocity prevented the local emitted pollutants in Beijing from being transported outside,and as a result,local emissions constituted a larger contribution in Beijing.

关键词： 2022 Winter Olympics PM_(2.5) Source apportionment

Limited Contribution of Preferential Dissolution to Radiogenic Uranium Isotope Disequilibrium Observed in Weathered Moraines

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Journal of Earth Science 2022年第1期33卷 57-66页

作者： Laifeng Li Laura FRobinson Tianyu Chen Zhewen Xu Jun Chen Gaojun Li MOE Key Laboratory of Surficial Geochemistry Department of Earth and Planetary SciencesNanjing UniversityNanjing 210023China School of Geography and Ocean Science Nanjing UniversityNanjing 210023China School of Earth Sciences University of BristolBristol BS81RJUK Frontiers Science Center for Critical Earth Material Cycling Nanjing UniversityNanjing 210023China

Radiogenic uranium isotope disequilibrium(^(234)U/^(238)U) has been used to trace a variety of Earth surface processes,and is usually attributed to direct recoil of ^(234)Th and preferential dissolution of radioactively damaged lattices at the mineral ***,the relative contribution of these two mechanisms in the natural environment remains unresolved,making it hard to use the extent of disequilibrium to quantify processes such as *** study tests the contribution of preferential dissolution using well-characterized weathered moraines and river sediments from the southeastern Tibetan *** observations show that weathering of recent moraines where the contribution from direct recoil is negligible and is not associated with depletion of ^(234)U at the mineral *** suggests a limited role for preferential dissolution in this *** attribute this lack of preferential dissolution to a near-to-equilibrium dissolution at the weathering interfaces,with little development of etch pits associated with radioactively damaged energetic sites.

关键词： preferential dissolution uranium isotope disequilibrium Gongga Mountain comminution comminution age etch pits

A review and evaluation of nonroad diesel mobile machinery emission control in China

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Journal of Environmental Sciences 2023年第1期123卷 30-40页

作者： Pengju Bie Liang Ji Huanxing Cui Gang Li Shunli Liu Ying Yuan Kebin He Huan Liu State Key Joint Laboratory of ESPC State Environmental Protection Key Laboratory of Sources and Control of Air Pollution ComplexSchool of EnvironmentInternational Joint Laboratory on Low Carbon Clean Energy InnovationTsinghua UniversityBeijing 100084China State Environmental Protection Key Laboratory of Vehicle Emission Control and Simulation Chinese Research Academy of Environmental SciencesBeijing 100012China Jinan Automobile Testing Center Co Ltd.Jinan 250102China

China’s emission control for nonroad diesel mobile machinery(NDMM)must deal with a fast increase in stock as well as regulations that are two decades behind those for on-road *** study provides the first large-scale review and evaluation of China’s NDMM policies,along with emission measurements and an investigation on diesel fuel *** sulfur contents of the investigated diesel declined from 430 ppm(median value)in 2011 to6-8 ppm during the 2017-2018 *** emission control of NO_(x)and PM greatly improved with the shift from the China II to China IV standards,as demonstrated by engine tests and field NO_(x)***,the NO_(x)emission factors for non-type-approved engines were approximately twice the limits of the China II *** compliance based on bench tests was not sufficient to control actual emissions because the field-measured NO_(x)emission factors of all machinery ranged from 24%to 225%greater than the respective emission limits for the *** circumstances adversely affected the effectiveness of the regulations and policies for China’s emission control of ***,the policies on new and in-use NDMM,as well as diesel fuel quality,prevented NO_(x)and PM emissions amounting to 4.4 Tg and 297.8 Gg during the period 2008-2017,*** emission management strategy contributed to enhancing the international competitiveness of China’s NDMM industries by promoting advanced *** effective NDMM emission control in the future,portable testing and noncontact remote supervision should be strengthened;also,the issue of noncompliant diesel should be addressed through rigorous control measures and financial penalties.

关键词： Nonroad mobile machinery Emission reduction Emission control policy Emission factor Diesel fuel quality

A Revisit of Shape Editing Techniques:From the Geometric to the Neural Viewpoint

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Journal of Computer Science & Technology 2021年第3期36卷 520-554页

作者： Yu-Jie Yuan Yu-Kun Lai Tong Wu Lin Gao Ligang Liu Beijing Key Laboratory of Mobile Computing and Pervasive Device Institute of Computing Technology Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China School of Computer Science and Informatics Cardiff UniversityCardiff CF243AAU.K. School of Mathematical Sciences University of Science and Technology of ChinaHefei 230026China

3D shape editing is widely used in a range of applications such as movie production,computer games and computer aided *** is also a popular research topic in computer graphics and computer *** past decades,researchers have developed a series of editing methods to make the editing process faster,more robust,and more ***,the deformed shape is determined by the optimal transformation and weights for an energy *** increasing availability of 3D shapes on the Internet,data-driven methods were proposed to improve the editing *** recently as the deep neural networks became popular,many deep learning based editing methods have been developed in this field,which are naturally *** mainly survey recent research studies from the geometric viewpoint to those emerging neural deformation techniques and categorize them into organic shape editing methods and man-made model editing *** traditional methods and recent neural network based methods are reviewed.

关键词： mesh deformation man-made model editing deformation representation optimization deep learning

Interaction of polyhydroxy fullerenes with ferrihydrite：adsorption and aggregation

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Journal of Environmental Sciences 2018年第2期30卷 1-9页

作者： Jing Liu Runliang Zhu Tianyuan Xu Mingwang Laipan Yanping Zhu Qing Zhou Jianxi Zhu Hongping He Key Laboratory of Mineralogy and Metallogeny Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangdong Provincial Key Laboratory of Mineral Physics and Material Research & Development Guangzhou 510640 China University of Chinese Academy of Sciences Beijing 100049 China

The rapid development of nanoscience and nanotechnology, with thousands types of nanomaterials being produced, will lead to various environmental impacts. Thus,understanding the behaviors and fate of these nanomaterials is essential. This study focused on the interaction between polyhydroxy fullerenes（PHF） and ferrihydrite（Fh）, a widespread iron（oxyhydr）oxide nanomineral and geosorbent. Our results showed that PHF were effectively adsorbed by Fh. The adsorption isotherm fitted the D-R model well, with an adsorption capacity of 67.1 mg/g. The adsorption mean free energy of 10.72 k J/mol suggested that PHF were chemisorbed on Fh. An increase in the solution p H and a decrease of the Fh surface zeta potential were observed after the adsorption of PHF on Fh; moreover, increasing initial solution p H led to a reduction of adsorption. The Fourier transform infrared spectra detected a red shift of C–O stretching from 1075 to 1062 cm-1 and a decrease of Fe–O bending, implying the interaction between PHF oxygenic functional groups and Fh surface hydroxyls. On the other hand, PHF affected the aggregation and reactivity of Fh by changing its surface physicochemical properties. Aggregation of PHF and Fh with individual particle sizes increasing from 2 nm to larger than 5 nm was measured by atomic force microscopy. The uniform distribution of C and Fe suggested that the aggregates of Fh were possibly bridged by PHF. Our results indicated that the interaction between PHF and Fh could evidently influence the migration of PHF, as well as the aggregation and reactivity of Fh.

关键词： Nanoparticles Polyhydroxy fullerenes Ferrihydrite Adsorption Aggregation

Photocatalytic Aerobic Oxysulfonylation of Alkynes to Access β-Keto Sulfones Catalyzed by OVs-N-Nb_(2)O_(5)

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Chinese Journal of Chemistry 2022年第22期40卷 2618-2624页

作者： Tao Song Yinpan Zhang Chun Wang Yafei Li Yong Yang CAS Key Laboratory of Bio-based Materials Qingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesShandong Energy InstituteQingdaoNewEnergyShandongLaboratoryQingdaoShandong266101China Schoolof Chemistry and Materials Science Nanjing Normal UniversityNanjingJiangsu 210023China

Herein,we report a novel heterogeneous photocatalyst for radical-mediated oxidative oxysulfonylation of alkynes toβ-keto sulfones under environmentally benign *** oxygen vacancy-rich semiconductor Nb2O5(labeled as OVs-N-Nb_(2)O_(5))could efficiently catalyze a wide range of alkynes,especially for those bearing electron-deficient substituents or internal alkynes,to their correspondingβ-keto sulfones in good to high yields with good tolerance of diverse functional groups under visible-light *** late-stage modification of steroidal compounds and synthesis of bioactive molecules were also achieved via this procedure,highlighting its potential for practical ***,the photocatalyst OVs-N-Nb_(2)O_(5) showed outstanding catalytic stability for successive recycles without appreciable loss in activity and *** critical role of oxygen vacancies on improving reaction activity and selectivity was clearly disclosed via control experiments and theoretical calculation.

关键词： Oxygen vacancies Semiconducts Photocatalysis Oxysulfonylation of alkynes β-Keto sulfones

State-of-the-art progress in overall water splitting of carbon nitride based photocatalysts

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Frontiers in Energy 2021年第3期15卷 600-620页

作者： Bing LUO Yuxin ZHAO Dengwei JING School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 710049China International Research Center for Renewable Energy and State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

Converting solar energy into hydrogen(H_(2))by photocatalytic water splitting is a promising approach to simultaneously address the increasing energy demand and environmental *** decade has passed since the discovery of photo-induced water splitting phenomenon on TiO_(2)photoanode,while the solar to H_(2) efficiency is still around 1%,far below the least industrial ***,developing efficient photocatalyst with a high energy conversion efficiency is still one of the main tasks to be *** carbon nitride(g-C_(3)N_(4))is just such an emerging and potential ***,in this review,the state-of-the-art advances in g-C_(3)N_(4)based photocatalysts for overall water splitting were summarized in three sections according to the strategies used,and future challenges and new directions were discussed.

关键词： photocatalysis overall water splitting carbon nitride hydrogen

A Novel Separability Objective Function in CNN for Feature Extraction of SAR Images

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Chinese Journal of Electronics 2019年第2期28卷 423-429页

作者： GAO Fei WANG Meng WANG Jun YANG Erfu ZHOU Huiyu Department of Electronic and Information Engineering Beihang University Department of Design Manufacture and Engineering Management (DMEM) University of Strathclyde Department of Informatics University of Leicester

Convolutional neural network(CNN) has become a promising method for Synthetic aperture radar(SAR) target recognition. Existing CNN models aim at seeking the best separation between classes, but rarely care about the separability of them. We performs a separability measure by analyzing the property of linear separability, and proposes an objective function for CNN to extract linearly separable features. The experimental results indicate the output features are linearly separable,and the classification results are comparable with the other state of the art techniques.

关键词： Synthetic aperture radar(SAR) Convolution neural network(CNN) Classification Linear separability Objective function