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Spatial correlations in time and frequency domains between chlorophyll-a concentration and environmental factors in the Bohai Sea

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Journal of Oceanology and Limnology 2024年第4期42卷 1143-1156页

作者： Wan XU Di MU Zhenteng YANG Dekui YUAN Department of Mechanics Tianjin UniversityTianjin 300350China Engineering Research Center of Seawater Utilization of Ministry of Education School of Chemical Engineering and TechnologyHebei University of TechnologyTianjin 300130China State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China

Based on the reconstructed MODIS data and ECMWF reanalysis data from 2003 to 2021,spatial correlations between chlorophyll a(Chl a)and sea surface temperature(SST),photosynthetically available radiation(PAR),aerosol optical thickness(AOT),and wind speed(WS)in the Bohai Sea were analyzed from the perspective of time domain and frequency *** indicate that the frequency domain analysis was more conducive to revealing the correlations between Chl a and environmental *** spatial pattern of time-domain correlations was similar to the isobaths of the Bohai Sea,which was positive in shallow waters and negative in deep waters for SST,PAR,and AOT,and was reversed for ***-domain correlations were obtained by performing Fourier Transform and were higher than correlations in time *** spatial distributions indicated that the effects of SST and PAR on Chl a were greater than AOT and WS in the Bohai ***,cross-spectrum analysis was applied to explore the response relationships.A depth-dependent pattern was shown in correlations and time lags,indicating that the influential mechanism of environmental factors on Chl-a concentration is related to seawater depth.

关键词： chlorophyll a(Chl a) frequency domain spatial correlation Bohai Sea

Electrocatalytic coupling of anodic nitrogen oxidation and cathodic nitrate reduction for ammonia synthesis from air and water

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Nano Research 2024年第9期17卷 7824-7829页

作者： Aijing Ma Jianzhou Gui Yanmei Huang Yifu Yu State Key Laboratory of Separation Membranes and Membrane Processes Tianjin Key Laboratory of Green Chemical Technology and Process EngineeringSchool of Chemical Engineering and TechnologyTiangong UniversityTianjin 300387China Institute of Molecular Plus School of Chemical EngineeringTianjin UniversityTianjin 300072China

Ammonia plays a vital role in present agriculture and industry,and is also regarded as a next-generation clean energy *** development of electrocatalysis raises an opportunity to make ammonia synthesis compatible with intermittent and variable renewable energy sources such as solar and wind ***,the direct ammonia electrosynthesis from N_(2)reduction is still challenging due to the much easier hydrogen evolution competition *** this perspective,we propose a novel strategy for ammonia electrosynthesis from air and water based on the coupling of anodic nitrogen oxidation and cathodic nitrate *** methods for breaking the bottlenecks of anodic nitrogen oxidation and cathodic nitrate reduction are discussed *** that,key issues that need to be considered in the coupled system are proposed for the application of this strategy.

关键词： electrocatalysis nitrogen oxidation nitrate reduction nitrogen fixation ammonia synthesis

Study on the mechanism and law of temperature,humidity and moisture content on the mechanical properties of molded fiber products

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Journal of Bioresources and Bioproducts 2024年第3期9卷 351-368页

作者： Zhiqiang Fu Tong Zhao Hu Wang Jingyi Wei Haozhe Liu Liying Duan Yan Wang Ruixiang Yan School of Light Industry Science and Engineering Tianjin University of Science and TechnologyTianjin 300457China Department of Transportation and Vehicle Engineering Tangshan UniversityTangshan 063000HebeiChina College of Mechanical Engineering Tianjin University of Science and TechnologyTianjin 300457China

The change of temperature, humidity and moisture content (MC) will lead to the change of mechanical properties of molded fiber products (MFP). However, it is difficult to decouple the effects of temperature, humidity and MC on the mechanical properties of MFP, and predict the mechanical properties of MFP during the use. In this study, the laws and mechanism of mechanical properties of MFP with ambient temperature, humidity and MC were studied. The results showed that the direct effect of temperature (20−70 °C) on mechanical properties of MFP was insignificant, and the mechanical properties of MFP were mainly changed by MC. The MC was related to ambient temperature and humidity, and the relationship between the three could be described by the modified Guggenheim-Anderson-de Boer (GAB) model (20−70 °C and 30 %–90 % relative humidity). With the increase of MC, the elastic modulus and fracture strain was increased and decreased linearly, the yield strength and failure strength were presented GaussAmp laws, and the failure strain was presented asymptotic regressed distribution law. Two fracture modes of MFP, brittle fracture and ductile fracture, were revealed by the scanning electron microscopy of the mesoscopic fiber structure of sugarcane bagasse molded fiber products. The mathematical models and the changes of fiber structure were verified by wheat straw molded fiber products and waste paper molded fiber products. This study was contributed to understand the effects and mechanism of the change of temperature, humidity and MC on the mechanical properties of MFP.

关键词： Temperature Relative humidity Moisture content Molded fiber products Mechanical properties

A column-shared histogramming TDC with pixel-to-pixel coincidence detection and compact analog counters for Flash LiDAR sensor

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Science China(Information Sciences) 2024年第8期67卷 345-346页

作者： Haoran WU Kaiming NIE Jiangtao XU Qinglong LIN Yingying JIAO School of Microelectronics Tianjin University tianjin Key Laboratory of Imaging and Sensing Microelectronic technology

In recent years, Flash LiDAR sensors based on direct timeof-flight(DToF) have been playing an increasingly important role in various 3D imaging fields. In order to perform a histogram on the chip to reduce the data rate, it is inevitable to use a large-size histogramming time-to-digital converter(hTDC) in a Flash LiDAR sensor. However, a large-size hTDC limits the spatial resolution of the sensor.

关键词： Pixels

Sabatier principle guiding the design of cathode catalysts for Li-CO2 batteries

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Journal of Energy Chemistry 2024年第10期97卷 585-592页

作者： Haonan Xie Yimin Zhang Biao Chen Chunnian He Chunsheng Shi Enzuo Liu Naiqin Zhao School of Materials Science and Engineering Tianjin Key Laboratory of Composite and Functional Materials Key Laboratory of Advanced Ceramics and Machining Technology (Ministry of Education) Tianjin University National Industry-Education Platform of Energy Storage Tianjin University Joint School of National university of Singapore and tianjin university International Campus of Tianjin University

The Sabatier principle has been widely used for designing electrocatalysts for energy conversion applications,but it is rarely mentioned in the research of cathode catalyst of *** our work,the "volcanic" relationship between the catalytic activity and the adsorption energy of the catalyst to the intermediates is first demonstrated based on the first-principles calculation,which meets the Sabatier principle and can be used to design the cathode *** increases in the number of nitrogenvacancy in WN shift the d-band center and increase the interaction with the *** catalytic activity increases first and then decreases with the increase of adsorption energy,which was proved in the *** optimal catalyst for moderate adsorption of intermediate makes the thin LiaCO3distribute *** exhibits a median voltage difference of 0.68 V and an energy efficiency of 84.33% at20 μA cm-2with a limited capacity of 200 μA h cm-2.

关键词： Bidirectional catalyst Li-CO2 batteries Nitrogen-vacancy Sabatier principle Transition metal nitrides

Improved YOLOv5 foreign object detection for transmission lines

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Optoelectronics Letters 2024年第8期20卷 490-496页

作者： ZHOU Liming LI Shixin ZHU Zhiren CHEN Fankai LIU Chen DONG Xiuhuan Electrical Engineering Department Tianjin University of Technology and EducationTianjin 300222China

The traditional transmission line detection has the problems of low *** improve the performance,this paper proposes an improved you only look once version 5(YOLOv5)transmission line foreign object detection ***,efficient channel attention(ECA)module is introduced in the backbone network for focusing the target features and improving the feature extraction capability of the ***,bilinear interpolation upsampling is introduced in the neck network to improve the model detection ***,by integrating the efficient intersection over union(EIoU)loss function and Soft non-maximum suppression(Soft NMS)algorithm,the convergence speed of the model is accelerated while the detection effect of the model is *** to the original algorithm,the improved algorithm reduces the number of parameters by 16.4%,increases the mean average precision(mAP)@0.5 by 3.9%,mAP@0.5:0.95 by 6.3%,and increases the detection speed to 55.3 frames per second(FPS).The improved algorithm is able to improve the performance of the foreign object detection in transmission lines effectively.

关键词： network algorithm union

Collectively induced transparency and absorption in waveguide quantum electrodynamics with Bragg atom arrays

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Communications in Theoretical Physics 2024年第8期76卷 19-28页

作者： Haolei Cheng Wei Nie Center for Joint Quantum Studies and Department of Physics School of ScienceTianjin UniversityTianjin 300350China tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing technology Tianjin UniversityTianjin 300350China

Collective quantum states, such as subradiant and superradiant states, are useful for controlling optical responses in many-body quantum systems. In this work, we study novel collective quantum phenomena in waveguide-coupled Bragg atom arrays with inhomogeneous *** atoms without free-space dissipation, collectively induced transparency is produced by destructive quantum interference between subradiant and superradiant states. In a large Bragg atom array, multi-frequency photon transparency can be obtained by considering atoms with different frequencies. Interestingly, we find collectively induced absorption(CIA) by studying the influence of free-space dissipation on photon transport. Tunable atomic frequencies nontrivially modify decay rates of subradiant states. When the decay rate of a subradiant state equals to the free-space dissipation, photon absorption can reach a limit at a certain frequency. In other words, photon absorption is enhanced with low free-space dissipation, distinct from previous photon detection schemes. We also show multi-frequency CIA by properly adjusting atomic frequencies. Our work presents a way to manipulate collective quantum states and exotic optical properties in waveguide quantum electrodynamics(QED) systems.

关键词： waveguide quantum electrodynamics collective quantum states photon absorption Bragg atom array

∼2.5 nm pores in carbon-based cathode promise better zinc-iodine batteries

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Chinese Chemical Letters 2024年第5期35卷 471-476页

作者： Yajun Hou Chuanzheng Zhu Qiang Wang Xiaomeng Zhao Kun Luo Zongshuai Gong Zhihao Yuan School of Materials Science and Engineering Tianjin Key Laboratory of Photoelectric Materials&DevicesTianjin University of TechnologyTianjin 300384China

The relationship mechanism between the material pore structures and cathodic iodine chemistry plays a vital role in efficient Zn-I_(2) batteries,but is unclear,retarding further *** work innovatively indicates a great contribution of∼2.5nm pore structure of nanocarbons to efficient iodine adsorption,rapid I^(−)↔I_(2) conversion,and polyiodide inhibition,via scrupulously designing catalysts with controllable pore sizes *** I_(2)-loading within the designed nitrogen-doped nanocarbons can reach up to as high as 60.8 wt%.The batteries based on the cathode deliver impressive performances with a large capacity of 178.8 mAh/g and long-term cycling stability more than 4000 h at 5.0 ***,these is no polyiodide such as I_(3)−and I_(5)−detected during the charge-discharge processes from comprehensive electrochemical cyclic voltammetry,X-ray photoelectron spectroscopy,and Raman *** work provides a novel knowledge-guided concept for rational pore design,promising better Zn-I_(2) batteries,which is also hoped to benefit other advanced energy technologies,such as Li-S,Li-ion,and Al-I_(2) batteries.

关键词： Zinc-iodine batteries Structure-performance relationship Iodine conversion chemistry Cathode materials Porous carbon

Pushing the frontiers: Chip-based detection based on micro-and nano-structures

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Chinese Chemical Letters 2024年第4期35卷 86-98页

作者： Meihui Liu Xinyuan Zhou Xiao Li Zhenjie Xue Tie Wang tianjin Key Laboratory of Life and Health Detection Life and Health Intelligent Research InstituteTianjin University of TechnologyTianjin 300384China

Changes in trace substances in human metabolites, which are related to disease processes and health status, can serve as chemical markers for disease diagnosis and symptom monitoring. Real-time online detection is an inevitable trend for the future of health monitoring, and the construction of chips for detection faces major challenges. The response of sensors often fails to meet the requirements for chipbased detection of trace substances due to the low efficiency of interfacial heterogeneous reactions, necessitating a rational design approach for micro-and nano-structures to improve sensor performance with respect to sensitivity and detection limits. This review focuses on the influence of micro-and nanostructures that used in chip on sensing. Firstly, this review categorizes sensors into chemiresistors, electrochemical sensors, fluorescence sensors, and surface enhanced Raman scattering(SERS) sensors based on their sensing principle, which have significant applications in disease diagnosis. Subsequently, commencing from the application requirements in the field of sensing, this review focuses on the different structures of nanoparticle(NP) assemblies, including wire, layered, core-shell, hollow, concave and deformable structures. These structures change in the size, shape, and morphology of conventional structures to achieve characteristics such as ordered alignment, high specific surface area, space limitation,vertical diffusion, and swaying behavior with fluid, thereby addressing issues such as poor signal transmission efficiency, inadequate adsorption and capture capacity, and slow mass transfer speed during sensing. Finally, the design direction of micro-and nano-structures, and possible obstacles and solutions to promote chip-based detection have been discussed. It is hope that this article will inspire the exploration of interface micro-and nano-structures modulated sensing methods.

关键词： Chip-based detection Micro-and nano-structures Real-time online detection Sensing Health monitoring