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Overview of radar detection methods for low altitude targets in marine environments

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Journal of Systems Engineering and Electronics 2024年第1期35卷 1-13页

作者： YANG yong YANG Boyu School of Electronic Science National University of Defense TechnologyChangsha 410073China

In this paper,a comprehensive overview of radar detection methods for low-altitude targets in maritime environments is presented,focusing on the challenges posed by sea clutter and multipath *** performance of the radar detection methods under sea clutter,multipath,and combined conditions is categorized and summarized,and future research directions are outlined to enhance radar detection performance for low-altitude targets in maritime environments.

关键词： radar sea clutter multipath scattering detection low altitude target

Asymmetric reversible structural switching of a diene coordination polymer promoted by UV-visible light

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Science China Chemistry 2024年第2期67卷 536-541页

作者： yong Wang Qiaoqiao Zhang yong-yong Cao Qi Liu Brendan F.Abrahams Jian-Ping Lang College of Chemistry Chemical Engineering and MaterialsSoochow UniversitySuzhou215123China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai200032China College of Biological Chemical Science and EngineeringJiaxing UniversityJiaxing314001China School of Chemistry University of MelbourneVictoria3010Australia

In natural and artificial systems,reversible reactions are commonly asymmetric with respect to the time scale and nature of the stimuli which drive the forward and backward *** applications for which switching behavior is required,it is desirable that the reversible reaction goes as close to symmetric as possible;however,such systems are ***,we report an example of ultraviolet(UV)-visible light-regulated asymmetric reversible structural switching involving a diene-based coordination polymer,CP1 and its monocyclobutane product,*** is possible to cycle at least ten times through a forward [2+2] photocycloaddition reaction and the reverse,photocleavage reaction.A single cycle can be completed within a few *** transformation is accompanied by fast and distinct fluorescence changes,arising from optimisation of the reaction *** functional theory calculations allow rationalisation of the asymmetric reversible transformation between CP1 and CP1a rather than between CP1 and its dicyclobutane product *** work provides a clear illustration of reversible structural switching which approaches symmetric behaviour with respect to reaction rate and *** insights gained from this work also assist in the design of fast,reversible switching materials.

关键词： asymmetrical reversible structural switching coordination polymer photocycloaddition UV-visible light-controlled fluorescence switching

Girvanella fossils from the Phanerozoic:Distribution, evolution and controlling factors

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Journal of Palaeogeography 2024年第4期13卷 924-938页

作者： Hua-Shan Zhang Ming-Yue dai yong-An Qi Lan-Lan Han Zhong-Lei Yin Song-Hua Chen Liang-Biao Lin Institute of Sedimentary Geology Chengdu University of Technology School of Resources and Environment Henan Polytechnic University

Girvanella is one of the common genera of cyanobacteria that plays a monumental role in the evolution of life on Earth and the formation of *** on a detailed search in the literature of Girvanella fossils,we have compiled a global database of Girvanella fossils and revealed the evolution of Girvanella fossils throughout the *** species,Girvanella kasakiensis,Girvanella problematica,Girvanella wetheredii,and Girvanella staminea,are recognized and *** data show that Girvanella fossils have well-defined temporal distribution during the Paleozoic Era,have a significant temporal gap in the Mesozoic Era,and have only been recorded sporadically in the Cenozoic *** were relatively abundant during the Cambrian Epoch 2-Early Ordovician,Late Ordovician,Late Devonian-Mississippian,and tended to lesser degrees during the Silurian-Early Devonian,Lopingian Epoch-Middle Jurassic,and Cretaceous-Present ***,the evolution of the abundance and diversity of Girvanella fossils was fundamentally consistent and showed episodical declining during the *** further explore these relationships,we thoroughly compared them with environmental factors such as seawater carbonate saturation state,Ca2+concentration,pH values,and atmospheric partial pressure of carbon dioxide （p CO2）.This study indicates that seawater carbonate saturation state and Ca2+concentration are major controls on secular patterns of the abundance and diversity of Girvanella fossils,together with the secondary factors of pH values and p *** the long history of Girvanella fossils,their abundance and diversity offer the potential to assist the interpretation of the long-term evolution of marine and atmosphere components during the Phanerozoic.

关键词： Girvanella Temporal distribution Abundance Diversity Control factors

Spontaneous ignition of corrugated cardboard under dynamic high radiant flux

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Defence Technology（防务技术） 2024年第10期40卷 65-77页

作者： Liu Liu Yan Gu Hong Yang Xing Wang Yang Zhou Xiaogan dai yong Han Shanggang Wen Ming Li Congmei Lin Changgen Feng Fei Tang Yushi Wen Institute of Chemical Materials China Academy of Engineering PhysicsMianyang 621999China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei 230026China Institute of Applied Physics and Computational Mathematics China Academy of Engineering PhysicsBeijing 100088China

Understanding the response of solid combustibles under high radiant fluxes is critical in predicting the thermal damage from extreme *** the more moderate radiant fluxes in conventional hydrocarbon fires,extreme events such as strong explosion,concentrated sunlight and directed energy can generate dynamic radiant fluxes at the MW/m^(2) level,creating a unique threat to *** study investigates the pyrolysis and spontaneous ignition behaviors of corrugated cardboard by using both experimental and numerical methods,under 10-cm dynamic high radiant fluxes ranging from 0.2 to 1.25 MW/m^(2) for 10 *** spontaneous ignition process at dynamic high radiant fluxes was recorded and *** ignition modes were found at the critical radiant flux of 0.4 MW/m^(2),namely hot-gas spontaneous ignition and hot-residue piloted *** latter is not the focus of this paper due to its extremely small probability of *** research reveals that the increase in flux intensity induces shorter delay times for both pyrolysis and ignition,lower ignition energy density,along with a corresponding rise in the critical mass flux and surface temperature at ignition *** simulation results are generally aligned with the experimental findings,despite some divergences may be attributed to model simplifications and parameter *** work contributes to a deeper insight into material behavior under extreme radiation,with valuable implications for fire safety and hazard assessment.

关键词： Extreme radiation Fire safety Corrugated cardboard Pyrolysis Ignition temperature

习近平法治思想对推进中国式法治现代化的理论创新

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学习与探索 2024年第6期 1-9页

作者：周佑勇全国人大社会建设委员会

中国式法治现代化是中国式现代化在法治领域的集中体现,其实质就是建构中国的现代法治,实现法治中国的现代化转型。习近平法治思想作为新时代全面依法治国的根本遵循和行动指南,始终紧贴法治中国建设的伟大实践,深刻揭示了推进中国式法... 详细信息

中国式法治现代化是中国式现代化在法治领域的集中体现,其实质就是建构中国的现代法治,实现法治中国的现代化转型。习近平法治思想作为新时代全面依法治国的根本遵循和行动指南,始终紧贴法治中国建设的伟大实践,深刻揭示了推进中国式法治现代化的内在逻辑,明确提出了推进中国式法治现代化的发展道路,科学指明了推进中国式法治现代化的立场观点方法,深入推动了中国式法治现代化对中华优秀传统法律文化的传承创新,实现了对推进中国式法治现代化的重大理论创新。

关键词：习近平法治思想中国式法治现代化中国式现代化法治中国建设

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Polyethylene to gasoline via a self-supplied hydrogen strategy

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Science China Chemistry 2024年第10期67卷 3187-3188页

作者： yong Tang State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

Polyethylenes(PEs)are one of the most widely used plastics in almost every aspect of modern life and are produced on a huge scale(a market volume of 110.13 million metric tons worldwide in 2022)[1].A large portion of the PEs are used once and discarded as waste,which caused severe problems such as plastic pollution as well as a waste of the fossoil resource.

关键词： pollution plastics strategy

Research on the influences of motion characteristics of jetting projectile charge under water

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Defence Technology（防务技术） 2024年第3期33卷 411-425页

作者： Xing Chen yong-gang Lu Institute of Systems Engineering China Academy of Engineering PhysicsMianyang 621900SichuanChina

Shaped charge warhead is important for enhancing the damage performance of underwater *** paper used finite element analysis software and based on JPC water penetration experiments to examine the influence of liner parameters(wall thickness,material),charge aspect ratio,and stand-off distance on the movement characteristics of JPC in *** findings reveal that the head diameter of the JPC increases and experiences significant erosion after entering the water,the effective length of the JPC in water undergoes two distinct phases:a growth phase and a decrease phase,with the velocity of the JPC decaying *** the liner thickness,stand-off distance and the charge aspect ratio can improve the erosion resistance and the velocity retention capacity of the *** optimal ranges for liner thickness and stand-off distance are 0.0363D_(k) to 0.0545D_(k)(D_(k) is the charge diameter),the stand-off distance should be within 1.0D_(k).After the charge aspect ratio higher than 1.25,the charge structure exerts minimal influence the movement characteristics of the JPC in *** density plays a crucial role in the velocity decay pattern of the JPC during *** with higher densities exhibit superior velocity retention capabilities in water,with the velocity decay pattern converging if the densities are ***,copper,tantalum and tungsten liners are deemed appropriate for underwater shaped charge ***,the results will provide an important reference for the design of underwater shaped charge warhead.

关键词： JPC Movement characteristics Underwater penetration Numerical simulation

Optimizing multi-parameter distributed fiber sensors:a hybrid Rayleigh-Brillouin-Raman System approach

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Light(Science & Applications) 2024年第3期13卷 393-395页

作者： Kwang yong Song Dept.of Physics Chung-Ang University84 Heukseok-roDongjak-guSeoul 06974Korea

An optimized single-end hybrid Rayleigh,Brillouin,and Raman distributed fiber sensing system has been developed for simultaneous measurement of multiple *** system integrates 3-bit pulse coding for the Raman signal and the Brillouin amplification of the Rayleigh-backscattered signal,discriminating strain,temperature,and vibration using a single sensing fiber.

关键词： fiber Rayleigh signal

Long-term operation optimization of circulating cooling water systems under fouling conditions

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Chinese Journal of Chemical Engineering 2024年第1期65卷 255-267页

作者： Jiarui Liang yong Tian Shutong Yang yong Wang Ruiqi Yin Yufei Wang School of Chemical Engineering and Environment China University of PetroleumBeijing102249China CHN Energy Xinjiang Chemical Co. LTDUrumqi830092China College of Mechanical and Transportation Engineering China University of PetroleumBeijing 102249China

Fouling caused by excess metal ions in hard water can negatively impact the performance of the circulating cooling water system(CCWS)by depositing ions on the heat exchanger's ***,the operation optimization of CCWS often prioritizes short-term flow velocity optimization for minimizing power consumption,without considering ***,low flow velocity promotes ***,it's crucial to balance fouling and energy/water conservation for optimal CCWS long-term *** study proposes a mixed-integer nonlinear programming(MINLP)model to achieve this *** model considers fouling in the pipeline,dynamic concentration cycle,and variable frequency drive to optimize the synergy between heat transfer,pressure drop,and *** optimizing the concentration cycle of the CCWS,water conservation and fouling control can be *** model can obtain the optimal operating parameters for different operation intervals,including the number of pumps,frequency,and valve local resistance *** experiments on cycle and environmental temperature reveal that as the cycle increases,the marginal benefits of energy/water conservation *** periods with minimal impact on fouling rate,energy/water conservation can be achieved by increasing the cycle while maintaining a low fouling ***,the proposed model has significant energy/water saving effects and can comprehensively optimize the CCWS through its incorporation of fouling and cycle optimization.

关键词： Computer simulation Circulating water system Fouling Concentration cycle Optimization Variable frequency drive