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Quantitative method for calculating spatial release region for laser-guided bomb

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Journal of Systems Engineering and Electronics 2024年第4期35卷 1053-1062页

作者： YANG Ping XIAO bing CHEN Xin hao Yuntao Air Force Early Warning Academy Wuhan 430019China Unit 93175 of the PLA Changchun 136000China

The laser-guided bomb(LGB)is an air-to-ground pre-cision-guided weapon that offers high hit rates,great power,and ease of *** are guided by semi-active laser ground-seek-ing technology,which means that atmospheric conditions can affect their *** spatial release region(SRR)of LGBs is difficult to calculate precisely,especially when there is a poor field of *** can result in a lower real hit *** increase the hit probability of LGBs in tough atmospheric situa-tions,a novel method for calculating the SRR has been *** method is based on the transmittance model of the 1.06μm laser in atmospheric species and the laser diffuse reflection model of the target surface to determine the capture target time of the laser ***,it calculates the boundary ballistic space starting position by ballistic model and gets the spatial scope of the spatial release *** method can determine the release region of LGBs based on flight test data such as instantaneous velocity,altitude,off-axis angle,and atmospheric *** more effectively employing aircraft release conditions,atmospheric visibility and other factors,the SRR calculation method can improve LGB hit probabi-lity by 9.2..

关键词： laser-guided bombs(LGBs) hit probability atmo-spheric transmittance spatial release region(SRR)boundary ballistic

Mechanism of local solidification time variations with melt rate during vacuum arc remelting process of 8Cr4Mo4V high-strength steel

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Journal of Iron and Steel Research International 2024年第2期31卷 377-388页

作者： Tao Pan Hong-chun Zhu Zhou-hua Jiang Hua-bing Li Rui Zhang hao Feng School of Metallurgy Northeastern UniversityShenyang110819LiaoningChina State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819LiaoningChina

A 2. axisymmetric numerical model was established to investigate the variations of molten pool with different melt rates during the vacuum arc remelting of 8Cr4Mo4V high-strength steel,and the ingot growth was simulated by dynamic mesh *** results show that as the ingot grows,the molten pool profile changes from shallow and flat to V-shaped,and both the molten pool depth and the mushy width ***,the variation of both the molten pool shape and the mushy width melt rate is clarified by the thermal equilibrium *** melt rate increases,both the molten pool depth and the mushy width *** is caused by the increment in sensible heat stored in the ingot due to the limitation of the cooling capacity of the *** nonlinear increment in sensible heat leads to a nonlinear increase in the mushy *** addition,as melt rate increases,the local solidification time(LST)of ingot decreases obviously at first and then *** melt rate is controlled in a suitable range,LST is the lowest and the secondary dendrite arm spacing of the ingot is the smallest,which can effectively improve the compactness degree of 8Cr4Mo4V high-strength steel.

关键词： 8Cr4Mo4V high-strength steel Vacuum arc remelting process Melt rate Molten pool Local solidification time

Acute upper gastrointestinal bleeding due to portal hypertension in a patient with primary myelofibrosis:A case report

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World Journal of Clinical Cases 2024年第15期12卷 2621-2626页

作者： Yu Chen bing-bing Kong He Yin {2. Liu Sheng Wu Ting Xu Department of Emergency Beijing Tsinghua Changgung HospitalSchool of Clinical MedicineTsinghua UniversityBeijing 102218China Department of Pathology Beijing Tsinghua Changgung HospitalSchool of Clinical MedicineTsinghua UniversityBeijing 102218China

BACKGROUND Acute upper gastrointestinal bleeding is a common medical emergency that has a 10%hospital mortality *** to the etiology,this disease can be divided into acute varicose veins and nonvaricose *** from esophageal varices is a life-threatening complication of portal *** hypertension is a clinical syndrome defined as a portal venous pressure that exceeds 10 *** is the most common cause of portal hypertension,and thrombosis of the portal system not associated with liver cirrhosis is the second most common cause of portal hypertension in the Western *** myeloproliferative disorders are the main cause of portal venous thrombosis,and somatic mutations in the Janus kinase 2.gene(JAK2.V617F)can be found in approximately 90% of polycythemia vera,50% of essential thrombocyrosis and 50% of primary *** SUMMARY We present a rare case of primary myelofibrosis with gastrointestinal bleeding as the primary manifestation that presented as portal-superior-splenic mesenteric vein *** blood tests revealed the presence of the JAK2.V617F *** marrow biopsy ultimately confirmed the diagnosis of myelofibrosis(MF-2.grade).CONCLUSION In patients with acute esophageal variceal bleeding due to portal hypertension and vein thrombosis without cirrhosis,the possibility of myeloproliferative neoplasms should be considered,and the JAK2.mutation test should be performed.

关键词： Acute esophageal variceal bleeding Portal hypertension Myelofibrosis JAK2.V617F mutation Case report

Electronic structure engineering of transition metal dichalcogenides for boosting hydrogen energy conversion electrocatalysts

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Chinese Physics B 2024年第9期33卷 13-28页

作者： bing hao Jingjing Guo Peizhi Liu Junjie Guo Key Laboratory of Interface Science and Engineering in Advanced Materials Ministry of EducationTaiyuan University of TechnologyTaiyuan 030024China

Electrocatalytic water splitting for hydrogen production is an appealing strategy to reduce carbon emissions and generate renewable *** promising process,however,is limited by its sluggish reaction kinetics and high-cost *** two-dimensional(2.)transition metal dichalcogenides(TMDCs)have presented great potential as electrocatalytic materials due to their tunable bandgaps,abundant defective active sites,and good chemical ***,phase engineering,defect engineering and interface engineering have been adopted to manipulate the electronic structure of TMDCs for boosting their exceptional catalytic ***,it is essential to clarify the local structure of catalytically active sites of TMDCs and their structural evolution in catalytic reactions using atomic resolution electron microscopy and the booming in situ technologies,which is beneficial for exploring the underlying reaction *** this review,the growth regulation,characterization,particularly atomic configurations of active sites in TMDCs are *** significant role of electron microscopy in the understanding of the growth mechanism,the controlled synthesis and functional optimization of 2. TMDCs are *** review will shed light on the design and synthesis of novel electrocatalysts with high performance,as well as prompt the application of advanced electron microscopy in the research of materials science.

关键词： TMDCs STEM hydrogen energy conversion active site identification

Brightness enhancement on random-distributed-feedback Raman fiber lasers pumped by multimode diodes

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High Power Laser Science and Engineering 2024年第3期12卷 69-76页

作者： Xiulu hao Chenchen Fan Yang Li Zhiyong Pan Jinyong Leng Tianfu Yao bing Lei Pu Zhou College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangshaChina Nanhu Laser Laboratory National University of Defense TechnologyChangshaChina

The power scaling on short wavelength(SW)fiber lasers operating around 1μm are in significant demand for applications in energy,environment and *** challenge for performance scalability of high-power SW lasers based on rare-earth-doped fiber primarily lies in the physical limitations,including reabsorption,amplified spontaneous emission and parasitic laser ***,we demonstrate an all-fiberized,purely passive SW(1018 nm)randomdistributed-feedback Raman fiber laser(RRFL)to validate the capability of achieving high-power output at SWs based on multimode laser diodes(LDs)direct *** pumped by multimode LDs,the high-brightness RRFL delivers over 656 W,with an electro-optical efficiency of 2.%relative to the *** slope efficiency is 94%.The beam quality M2.actor is 2.9(which is~2. times that of the pump)at the maximum output signal power,achieving the highest brightness enhancement of 14.9 in *** the best of our knowledge,this achievement also represents the highest power record of RRFLs utilizing multimode diodes for direct *** work may not only provide a new insight into the realization of high-power,high-brightness RRFLs but also is a promising contender in the power scaling of SWs below 1μm.

关键词： fiber laser purely passive gain random distributed feedback stimulated Raman scattering

A review of reservoir damage during hydraulic fracturing of deep and ultra-deep reservoirs

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Petroleum Science 2024年第1期21卷 384-409页

作者： Kun Zhang Xiong-Fei Liu Dao-bing Wang Bo Zheng Tun-hao Chen Qing Wang hao Bai Er-Dong Yao Fu-Jian Zhou National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum-BeijingBeijing102249China School of Mechanical Engineering Beijing Institute of Petrochemical TechnologyBeijing102617China Tuha Downhole Operation Company CNPC Xibu Drilling Engineering Company LimitedShanshan838200XinjiangChina

Deep and ultra-deep reservoirs have gradually become the primary focus of hydrocarbon exploration as a result of a series of significant discoveries in deep hydrocarbon exploration *** reservoirs present unique challenges due to their deep burial depth(4500-8882.m),low matrix permeability,complex crustal stress conditions,high temperature and pressure(HTHP,150-2.0℃,105-155 MPa),coupled with high salinity of formation ***,the costs associated with their exploitation and development are exceptionally *** deep and ultra-deep reservoirs,hydraulic fracturing is commonly used to achieve high and stable *** hydraulic fracturing,a substantial volume of fluid is injected into the ***,statistical analysis reveals that the flowback rate is typically less than 30%,leaving the majority of the fluid trapped within the ***,hydraulic fracturing in deep reservoirs not only enhances the reservoir permeability by creating artificial fractures but also damages reservoirs due to the fracturing fluids *** challenging“three-high”environment of a deep reservoir,characterized by high temperature,high pressure,and high salinity,exacerbates conventional forms of damage,including water sensitivity,retention of fracturing fluids,rock creep,and proppant *** addition,specific damage mechanisms come into play,such as fracturing fluid decomposition at elevated temperatures and proppant diagenetic reactions at HTHP ***,the foremost concern in deep oil and gas development lies in effectively assessing the damage inflicted on these reservoirs by hydraulic fracturing,comprehending the underlying mechanisms,and selecting appropriate ***'s noteworthy that the majority of existing studies on reservoir damage primarily focus on conventional reservoirs,with limited attention given to deep reservoirs and a lack of systematic *** light of this,our approach entails initially summarizin

关键词： Artificial fracture Deep and ultra-deep reservoir Fracture conductivity Fracturing fluid Hydraulic fracturing Reservoir damage

Gradient honeycomb metastructure with broadband microwave absorption and effective mechanical resistance

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Nano Materials Science 2024年第4期6卷 456-466页

作者： Dongmeng Li Xia Zheng hao Gu Xiaobo Xuan bing Liu Hongquan Feng Fuheng Zhang Shanghai Radio Equipment Research Institute

Multifunctional metastructure integrated broadband microwave absorption and effective mechanical resistance has attracted much attention. However, multifunctional performance is limited by the lack of theoretical approaches to integrated design. Herein, a multi-layer impedance gradient honeycomb(MIGH) was designed through theoretical analysis and simulation calculation, and fabricated using 3D printing technique. A theoretical calculation strategy for impedance gradient structure was established based on the electromagnetic parameter equivalent method and the multi-layer finite iterative method. The impedance of MIGH was analyzed by the theoretical calculation strategy to resolve the broadband absorption. Intrinsic loss mechanism of matrix materials and distributions of electric fields, magnetic fields and power loss were analyzed to investigate the absorption mechanism. Experimental results indicated that a 15 mm thick designed metastructure can achieve the absorption more than 88.9% in the frequency range of 2.18 GHz. Moreover, equivalent mechanical parameters of MIGH was calculated by integral method according to the Y-shaped model. Finite Element analysis of stress distributions were carried out to predict the deformation behavior. Mechanical tests demonstrate that MIGH achieved the compression modulus of 2..89 MPa and flexure modulus of 17.05 MPa. The integration of broadband electromagnetic absorption and effective mechanical resistance was achieved by the proposed design principle and fabrication methodology.

关键词： Multifunctional metastructure Broadband microwave absorption Impedance gradient calculation Mechanical characteristics Finite element analysis

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International Journal of Oral Science 2024年第3期16卷 398-412页

作者： Yunfan Zhang Jiale Yan Yuning Zhang hao Liu bing Han Weiran Li Department of Orthodontics Peking University School and Hospital of Stomatology&National Center for Stomatology&National Clinical Research Center for Oral Diseases&National Engineering Laboratory for Digital and Material Technology of Stomatology&Beijing Key Laboratory of Digital Stomatology&Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health&NMPA Key Laboratory for Dental MaterialsBeijingChina

Compared with teenage patients,adult patients generally show a slower rate of tooth movement and more pronounced alveolar bone loss during orthodontic treatment,indicating the maladaptation of alveolar bone homeostasis under orthodontic ***,this phenomenon is not well-elucidated to date,leading to increased treatment difficulties and unsatisfactory treatment outcomes in adult *** to provide a comprehensive knowledge and further inspire insightful understanding towards this issue,this review summarizes the current evidence and underlying *** age-related abatements in mechanosensing and mechanotransduction in adult cells and periodontal tissue may contribute to retarded and unbalanced bone metabolism,thus hindering alveolar bone reconstruction during orthodontic *** this end,periodontal surgery,physical and chemical cues are being developed to reactivate or rejuvenate the aging periodontium and restore the dynamic equilibrium of orthodontic-mediated alveolar bone *** anticipate that this review will present a general overview of the role that aging plays in orthodontic alveolar bone metabolism and shed new light on the prospective ways out of the impasse.

关键词： alveolar metabolism homeostasis

Amorphous electrocatalysts for urea oxidation reaction

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Progress in Natural Science:Materials International 2024年第2期34卷 362-375页

作者： Fenghui Guo Dongle Cheng Qian Chen hao Liu Zhiliang Wu Ning Han bing-Jie Ni Zhijie Chen School of Materials Science and Technology China University of Geosciences Shenzhen Academy of Metrology and Quality Inspection Centre for Technology in Water and Wastewater School of Civil and Environmental Engineering University of Technology Sydney College of Safety and Environmental Engineering Shandong University of Science and Technology Institute of Yellow River Delta Earth Surface Processes and Ecological Integrity Shandong University of Science and Technology Discipline of Chemical Engineering Western Australian School of Mines: Minerals Energy and Chemical Engineering Curtin University Department of Materials Engineering School of Civil and Environmental Engineering The University of New South Wales

Electrochemical urea oxidation reaction(UOR) is a promising alternative to oxygen evolution reaction(OER) for realizing energy-saving hydrogen production. Developing efficient electrocatalysts for UOR becomes a central challenge. Recently, amorphous materials have been extensively used as UOR catalysts because of their numerous defective sites and flexible electronic properties. In this review, recent advancements in the development of amorphous UOR electrocatalysts are analyzed. The UOR mechanism is discussed, and the design of amorphous catalysts is then analyzed. The main catalyst design strategies are illustrated, including nanostructure control,heteroatom doping, composition regulation, and heterostructure construction. Also, electrocatalysts' structureperformance correlation is interpreted. Perspectives in this field are proposed for guiding future studies on the development of high-performance amorphous catalysts towards energy sustainability.

关键词： Catalyst design Hydrogen energy Heterostructures Heteroatom doping Component regulation