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Effects of content and particle size of TiH2 powders on the energy output rules of RDX composite explosives

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Defence Technology（防务技术） 2024年第2期32卷 297-308页

作者： Hao Wang Yangfan cheng Shoujun Zhu Zihan li Zhaowu shen School of Chemical Engineering Anhui University of Science and TechnologyHuainan 232001China Anhui Engineering Laboratory of Explosive Materials and Technology Anhui University of Science and TechnologyHuainan 232001China School of Engineering Science University of Science and Technology of ChinaHefei 230027China

In order to improve the detonation characteristics of RDX,a RDX-based composite explosive with TiH_(2)powders was prepared.The effects of content and particle size of TiH_(2)powders on thermal safety,shock wave parameters and thermal damage effects of RDX-based composite explosive were studied with the C80 microcalorimeter,air blast experiment system and colorimetric thermometry method.Experimental results showed that TiH_(2)powders could enhance the thermal stability of RDX-based composite explosive and increase its ultimate decomposition heat.The content and particle size of TiH_(2)powders also had significant effects on the thermal safety,detonation velocity,shock wave parameters,fireball temperature and duration of RDX-based composite explosives.Furthermore,the differences of TiH_(2)and Ti powders on the detonation energy output rules of RDX-based composite explosives were also compared,showing that TiH_(2)powders had better influences on improving the explosion power and thermal damage effect of RDX-based composite explosives than Ti powders,for the participation of free H_(2)released by TiH_(2)powders in the detonation process.TiH_(2)powders have important research values as a novel energetic additive in the field of military composite explosives.

关键词： RDX Hydrogen storage alloy Air blast After-burn reaction Colorimetric thermometry

Deflagration characteristics of freely propagating flames in magnesium hydride dust clouds

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Defence Technology（防务技术） 2024年第1期31卷 471-483页

作者： Qiwei Zhang Yangfan cheng Beibei Zhang Danyi li Zhaowu shen School of Chemical Engineering Anhui University of Science and TechnologyHuainan 232001AnhuiPR China School of Civil Engineering and Architecture Anhui University of Science and TechnologyHuainan 232001AnhuiPR China Anhui Engineering Laboratory of Explosive Materials and Technology Anhui University of Science and TechnologyHuainan 232001AnhuiPR China School of Engineering Science University of Science and Technology of ChinaHefei 230027AnhuiPR China

The flame propagation processes of MgH_(2)dust clouds with four different particle sizes were recorded by a high-speed camera.The dynamic flame temperature distributions of MgH_(2)dust clouds were reconstructed by the two-color pyrometer technique,and the chemical composition of solid combustion residues were analyzed.The experimental results showed that the average flame propagation velocities of 23μm,40μm,60μm and 103μm MgH_(2)dust clouds in the stable propagation stage were 3.7 m/s,2.8 m/s,2.1 m/s and 0.9 m/s,respectively.The dust clouds with smaller particle sizes had faster flame propagation velocity and stronger oscillation intensity,and their flame temperature distributions were more even and the temperature gradients were smaller.The flame structures of MgH_(2)dust clouds were significantly affected by the particle sinking velocity,and the combustion processes were accompanied by micro-explosion of particles.The falling velocities of 23μm and 40μm MgH_(2)particles were 2.24 cm/s and 6.71 cm/s,respectively.While the falling velocities of 60μm and 103μm MgH_(2)particles were as high as 15.07 cm/s and 44.42 cm/s,respectively,leading to a more rapid downward development and irregular shape of the flame.Furthermore,the dehydrogenation reaction had a significant effect on the combustion performance of MgH_(2)dust.The combustion of H_(2)enhanced the ignition and combustion characteristics of MgH_(2)dust,resulting in a much higher explosion power than the pure Mg dust.The micro-structure characteristics and combustion residues composition analysis of MgH_(2)dust indicated that the combustion control mechanism of MgH_(2)dust flame was mainly the heterogeneous reaction,which was affected by the dehydrogenation reaction.

关键词： Magnesium hydride dust Flame combustion mechanism Particle size Dust explosion Two-color pyrometer

A robust genomic-based prognostic model for the assessment ofcancer stemness and survival for patients with hepatocellularcarcinoma

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Hepatobiliary & Pancreatic Diseases International 2024年第1期23卷 97-102页

作者： cheng-li Du shen-Yu Wei Yun-Hao Chen Kang-Jie Chen Division of Thoracic Surgery First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China Zhejiang University School of Medicine Hangzhou 310003China Division of Hepatobiliary Pancreatic Surgery First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China

To the Editor:Hepatocellular carcinoma(HCC)is an aggressive malignancy with poor long-term prognosis[1].liver cancer stem cell(CSC)can drive the metastasis,drug resistance,and recurrence of HCC[2].The regulatory mechanisms about liver cancer stemness have been investigated,which encouraged the identification and characterization of novel prognostic and therapeutic strategies for HCC[3].

关键词： cancer prognosis liver

Magnetic behaviors and magnetocaloric effects in rare earth high-entropy amorphous/nanocrystalline alloys

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Journal of Rare Earths 2024年第1期42卷 129-136,I0005页

作者： lin Xue liliang Shao Baosen Zhang Zongzhen li Jiangbo cheng Baolong shen College of Mechanics and Materials Hohai UniversityNanjing211106China School of Materials Science and Engineering Jiangsu Key Laboratory of Advanced Metallic MaterialsSoutheast UniversityNanjing211189China School of Materials Science and Engineering Nanjing Institute of TechnologyNanjing211167China Jiangsu JITRI Advanced Energy Materials Research Institute Co. Ltd.Changzhou213000China

Rare earth high-entropy alloys(RE-HEAs)exhibit great potential to be applied as refrigerants due to their good comprehensive magnetocaloric properties.In this work,octary GdTbDyHoErTmCoAl and GdTbDyHoErTmCoNi RE-HEAs with amorphous/nanocrystalline structure exhibiting comparable magnetocaloric effect were synthesized.Both RE-HEAs show a second-order magnetic phase transition in the temperature range of hydrogen liquefaction.Due to the complex magnetic interactions,a spin glasslike behavior at low temperatures is observed in the RE-HEAs.A superior magnetocaloric effect is obtained in the nanocrystalline GdTbDyHoErTmCoNi high-entropy alloy that is multiphase attributed to a stronger magnetic exchange interaction when compared with the other that exhibits single amorphous structure.Despite heterogeneous microstructure,homogeneous chemical distributions are observed in the partially crystallized high-entropy alloy.In addition,the magnetocaloric effect and magnetic transition behavior of rare earth medium-and high-entropy alloys,including the RE-HEAs in this study,are summarized and discussed.The results in this work provide a helpful guide for the design of RE-HEAs for hydrogen liquefaction applications with excellent magnetocaloric effects.

关键词： Rare earths High-entropy alloy Metallic glass Magnetocaloric effect

High-brightness green InP-based QLEDs enabled by in-situ passivating core surface with zinc myristate

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Materials Futures

Materials Futures 2024年第2期3卷 141-148页

作者： Yuanbin cheng Qian li Mengyuan Chen Fei Chen Zhenghui Wu Huaibin shen Key Laboratory for Special Functional Materials of Ministry of Education National&Local Joint Engineering Research Center for High-efficiency Display and Lighting TechnologyHenan UniversityKaifeng 475004People’s Republic of China

The performance of red InP and blue ZnTeSe-based quantum dots(QDs)and corresponding QD light emitting diodes(QLEDs)has already been improved significantly,whose external quantum efficiencies(EQEs)and luminances have exceeded 20%and 80000 cd m-2,respectively.However,the inferior performance of the green InP-based device hinders the commercialization of full-color Cd-free QLED technology.The ease of oxidation of the highly reactive InP cores leads to high non-radiative recombination and poor photoluminescence quantum yield(PL QY)of the InP-based core/shell QDs,limiting the performance of the relevant QLEDs.Here,we proposed a fluoride-free synthesis strategy to in-situ passivate the InP cores,in which zinc myristate reacted with phosphine dangling bonds to form Zn–P protective layer and protect InP cores from the water and oxygen in the environment.The resultant InP/ZnSe/ZnS core/shell QDs demonstrated a high PL QY of 91%.The corresponding green-emitting electroluminescence devices exhibited a maximum EQE of 12.74%,along with a luminance of over 175000 cd m^(-2)and a long T50@100 cd m^(-2)lifetime of over 20000 h.

关键词： quantum-dot light emitting diodes InP-based quantum dot in-situ passivation of core surface zinc myristate

CAV driving safety monitoring and warning via V2X-based edge computing system

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Frontiers of Engineering Management 2024年第1期11卷 107-127页

作者： cheng CHANG Jiawei ZHANG Kunpeng ZHANG Yichen ZHENG Mengkai SHI Jianming HU shen li li li Department of Automation Tsinghua UniversityBeijing 100084China College of Electrical Engineering Henan University of TechnologyZhengzhou 450001China Nebula link Technology Co. Ltd.Beijing 100080China Department of Civil Engineering Tsinghua UniversityBeijing 100084China

Driving safety and accident prevention are attracting increasing global interest.Current safety monitoring systems often face challenges such as limited spatiotemporal coverage and accuracy,leading to delays in alerting drivers about potential hazards.This study explores the use of edge computing for monitoring vehicle motion and issuing accident warnings,such as lane departures and vehicle collisions.Unlike traditional systems that depend on data from single vehicles,the cooperative vehicle-infrastructure system collects data directly from connected and automated vehicles(CAVs)via vehicle-to-everything communication.This approach facilitates a comprehensive assessment of each vehicle’s risk.We propose algorithms and specific data structures for evaluating accident risks associated with different CAVs.Furthermore,we examine the prerequisites for data accuracy and transmission delay to enhance the safety of CAV driving.The efficacy of this framework is validated through both simulated and real-world road tests,proving its utility in diverse driving conditions.

关键词： driving safety accident prevention connected and automated vehicles edge computing

Theoretical Analysis of Cooperative Driving at Idealized Unsignalized Intersections

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Tsinghua Science and Technology 2024年第1期29卷 257-270页

作者： shen li Jiawei Zhang Zhenwu Chen li li Department of Civil Engineering Tsinghua UniversityBeijing 100084China Department of Automation Tsinghua UniversityBeijing 100084China shenzhen Urban Transport Planning Center Co. Ltd.Shenzhen 518000China

Cooperative driving is widely viewed as a promising method to better utilize limited road resources and alleviate traffic congestion.In recent years,several cooperative driving approaches for idealized traffic scenarios(i.e.,uniform vehicle arrivals,lengths,and speeds)have been proposed.However,theoretical analyses and comparisons of these approaches are lacking.In this study,we propose a unified group-by-group zipper-style movement model to describe different approaches synthetically and evaluate their performance.We derive the maximum throughput for cooperative driving plans of idealized unsignalized intersections and discuss how to minimize the delay of vehicles.The obtained conclusions shed light on future cooperative driving studies.

关键词： cooperative driving connected and automated vehicles unsignalized intersection

Hydrodynamic Characteristics of Undular Tidal Bores in the Qiantang River Based on Field Observations

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China Ocean Engineering 2024年第3期38卷 505-518页

作者： ZHANG Shu-yu PAN Cun-hong ZHANG shen-yang li Ruo-hua cheng Wenlong XIE Dong-feng Zhejiang Tongji Vocational College of Science and Technology Hangzhou 311231China Zhejiang Institute of Hydraulics and Estuary Hangzhou 310020China

Understanding the undular tidal bores in the Qiantang River is essential for effective river management and maintenance.While breaking tidal bores have been studied extensively, reports on undular tidal bores in the Qiantang Riverremain limited. Furthermore, observed data on undular tidal bores fulfilling the requirements of short measurementtime intervals, and spring, medium, and neap tide coverage, and providing detailed data for the global vertical stratificationof flow velocity are quite limited. Based on field observations at Qige in the Qiantang estuary, we analyzedthe characteristics of undular tidal bores. The results showed that the flooding amplitude (a) of the first wave isalways larger than its ebbing amplitude (b). Moreover, the vertical distribution of the maximum flood velocity exhibitesthree shapes, influenced by the tidal range, while that of the maximum ebb velocity exhibites a single shape. Duringthe initial phase of the flood tide in the spring and medium tides, the upper water body experiences multiple oscillatingchanges along the flow direction, corresponding to the alternating process of the crest and trough of the tide levelupon the arrival of the tidal bore. The tidal range is a crucial parameter in tidal bore hydrodynamics. By establishingthe relationship between hydrodynamic parameters and tidal range, other hydrodynamic parameters, such as the tidalbore height, maximum flood depth–averaged velocity, maximum flood stratified velocity at the measurement points,and duration of the flood tide current, can be effectively predicted, thereby providing an important reference for rivermanagement and maintenance.

关键词： tidal bores Qiantang Estuary tidal bore height tidal bore velocity propagation speed

Auto-parametric resonance of a continuous-beam-bridge model under two-point periodic excitation:an experimental investigation and stability analysis

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 445-454页

作者： li Yuchun shen Chao liu Wei li Dong Department of Hydraulic Engineering College of Civil EngineeringTongji UniversityShanghai 200092China

The auto-parametric resonance of a continuous-beam bridge model subjected to a two-point periodic excitation is experimentally and numerically investigated in this study.An auto-parametric resonance experiment of the test model is conducted to observe and measure the auto-parametric resonance of a continuous beam under a two-point excitation on columns.The parametric vibration equation is established for the test model using the finite-element method.The auto-parametric resonance stability of the structure is analyzed by using Newmark's method and the energy-growth exponent method.The effects of the phase difference of the two-point excitation on the stability boundaries of auto-parametric resonance are studied for the test model.Compared with the experiment,the numerical instability predictions of auto-parametric resonance are consistent with the test phenomena,and the numerical stability boundaries of auto-parametric resonance agree with the experimental ones.For a continuous beam bridge,when the ratio of multipoint excitation frequency(applied to the columns)to natural frequency of the continuous girder is approximately equal to 2,the continuous beam may undergo a strong auto-parametric resonance.Combined with the present experiment and analysis,a hypothesis of Volgograd Bridge's serpentine vibration is discussed.

关键词： auto-parametric resonance continuous beam bridge model two-point excitation experimental investigation stability analysis vibration of Volgograd Bridge