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Deflagration and detonation induced by shock wave focusing at different Mach numbers

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Chinese Journal of Aeronautics 2024年第2期37卷 249-258页

作者： Zezhong YANG jun CHENG bo ZHANG School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai 200240China

Shock wave focusing is an effective way to create a hot spot or a high-pressure and hightemperature region at a certain place,showing its unique usage in detonation initiation,which is beneficial for the development of detonation-based engines.The flame propagation behavior after the autoignition induced by shock wave focusing is crucial to the formation and self-sustaining of the detonation wave.In this study,wedge reflectors with two different angles(60°and 90°)and a planar reflector are employed,and the Mach number of incident shock waves ranging from 2.0 to 2.8 is utilized to trigger different flame propagation modes.Dynamic pressure transducers and the high-speed schlieren imaging system are both employed to investigate the shock-shock collision and ignition procedure.The results reveal a total of four flame propagation modes:deflagration,DDT(Deflagration-to-Detonation Transition),unsteady detonation,and direct detonation.The detonation wave formed in the DDT and unsteady detonation mode is only approximately 75%-85%of the Chapman-Jouguet(C-J)speed;meanwhile,the directly induced detonation wave speed is close to the C-J speed.Transverse waves,which are strong evidence for the existence of detonation waves,are discovered in experiments.The usage of wedge reflectors significantly reduces the initial pressure difference ratio needed for direct detonation ignition.We also provide a practical method for differentiating between detonation and deflagration modes,which involves contrasting the speed of the reflected shock wave with the speed of the theoretically nonreactive reflected shock wave.These findings should serve as a reference for the detonation initiation technique in advanced detonation propulsion engines.

关键词： Deflagration Detonation Hydrogen Ignition Shock wave focusing

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Bio-inspired surface manipulation of halloysite nanotubes for highperformance flame retardant polylactic acid nanocomposites

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Nano Research 2024年第3期17卷 1595-1606页

作者： Yaru Sun Bin Yu Yan Liu junbo Yan Zixi xu bo Cheng Fenglei Huang jun Wang 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 Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China National Engineering Research Center of Flame Retardant Materials Beijing Institute of TechnologyBeijing 100081China

High-performance flame-retardant polylactic acid(PLA)bio-composites based on biobased fillers to meet usage requirements represents a promising direction for creating a sustainable world.Although flame retardant PLA composites have been reported extensively,it still remains a huge challenge to develop mechanically robust.The flame retardant PLA composites due to plastication effect of organic flame retardants and poor compatibility of organic fillers with the matrix lead to the severe deterioration in mechanical properties.In this work,a bio-inspired surface manipulation strategy for halloysite nanotubes(HNTs)was proposed via a facile and green self-assembly process.The structure and morphology of bio-inspired HNTs(b-HNTs)proved that biomass nanofillers(PA-NA-Fe)grew well both within the lumen and on the surface of HNTs.The growth of biomass on the inner and outer surfaces of HNTs was inspired from wooden towards enhancing the interface compatibility and imparting multi-properties to PLA biopolymer.Excellent mechanical properties(tensile,thermomechanical and anti-impact mechanical),great fire safety(heat release and smoke emission),thermostability and improved electromagnetic interference shielding effectiveness of this well-designed PLA nanocomposite were realized.The mechanisms of the enhanced performances of the PLA bio-composites by loading b-HNTs were proposed.This work presents a facile and environmentally-friendly bio-inspired modification strategy for HNTs to fabricate high-performance,multi-functional polymer composites,which is also suitable for surface modification of many other nanomaterials,including nanofibers,nanotubes,nanowires,and nanosheets.

关键词： mechanical properties thermostability fire safety electromagnetic interference shielding biomass

Toward tunable shape memory effect of NiTi alloy by grain size engineering:A phase field study

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Journal of Materials Science & Technology 2024年第1期168卷 276-289页

作者： bo xu Chong Wang Qingyuan Wang Failure Mechanics and Engineering Disaster Prevention Key Laboratory of Sichuan ProvinceSichuan UniversityChengdu 610065China Department of Mechanical Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Key Laboratory of Deep Underground Science and Engineering (Sichuan University)Ministry of EducationChengdu 610065China

The inelastic deformations of shape memory alloys(SMAs)always show poor controllability due to the avalanche-like martensite transformation,and the effective control for the deformation of precision de-vices has been not yet mature.In this work,the phase field method was used to investigate the shape memory effects(SMEs)of NiTi SMAs undergoing grain size(GS)engineering,to obtain tunable one-way and stress-assisted two-way SMEs(OWSME and SATWSME).The OWSME and SATWSME of the systems with various gradient-nanograin structures and bimodal grain structure,as well as that with geometric gradients were simulated.The simulated results indicate that due to the GS dependences of martensite transformation and reorientation,the occurrence and expansion of martensite reorientation,martensite transformation and its reverse can be efficaciously controlled via the GS engineering.When combining the GS engineering and geometric gradient design,since the effects of GS and stress gradient can be su-perimposed or competing,and the responses of martensite reorientation,martensite transformation and its reverse to this are different,the OWSME and SATWSME of the geometrically graded systems with various nanograin structures can exhibit different improvements in controllability.In short,the reorienta-tion hardening modulus during OWSME is increased and the transformation temperature window during SATWSME is widened by GS engineering,indicating the improved controllability of SMEs.The optimal GS engineering schemes revealed in this work provide the basic reference and guidance for designing tun-able SMEs and producing NiTi-based driving devices catering to desired functional performance in various engineering fields.

关键词： Phase field NiTi Shape memory effect Grain size engineering Geometric gradient

Young patient with a giant gastric bronchogenic cyst:A case report and review of literature

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World Journal of Clinical Cases 2024年第13期12卷 2254-2262页

作者： xu-Ren Lu xu-Guang Jiao Qi-Hang Sun bo-Wen Li Qing-Shun Zhu Guang-xu Zhu Jian-jun Qu School of Clinical Medicine Shandong Second Medical UniversityWeifang 261000Shandong ProvinceChina Department of Gastrointestinal Surgery Medical Center The First Affiliated HospitalShandong Second Medical UniversityWeifang 261000Shandong ProvinceChina

BACKGROUND Gastric bronchogenic cysts(BCs)are extremely rare cystic masses caused by abnormal development of the respiratory system during the embryonic period.Gastric bronchial cysts are rare lesions that were first reported in 1956;as of 2023,only 33 cases are available in the PubMed online database.BCs usually have no clinical symptoms in the early stage,and imaging findings also lack specificity.Therefore,they are difficult to diagnose before histopathological examination.CASE SUMMARY A 34-year-old woman with respiratory distress presented at our hospital.Endoscopic ultrasound revealed an anechoic mass between the spleen,left kidney and gastric fundus,with hyperechogenic and soft elastography textures and with a size of approximately 6.5 cm×4.0 cm.Furthermore,a computed tomography scan demonstrated high density between the posterior stomach and the spleen and the left kidney,with uniform internal density and a small amount of calcification.The maximum cross section was approximately 10.1 cm×6.1 cm,and the possibility of a cyst was high.Because the imaging findings did not suggest a malignancy and because the patient required complete resection,she underwent laparotomy surgery.Intraoperatively,this cystic lesion was found to be located in the posterior wall of the large curvature of the fundus and was approximately 8 cm×6 cm in size.Finally,the pathologists verified that the cyst in the fundus was a gastric BC.The patient recovered well,her symptoms of chest tightness disappeared,and the abdominal drain was removed on postoperative day 6,after which she was discharged on day 7 for 6 months of follow-up.She had no tumor recurrence or postoperative complications during the follow-up.CONCLUSION This is a valuable report as it describes an extremely rare case of gastric BC.Moreover,this was a very young patient with a large BC in the stomach.

关键词： Bronchogenic cyst Stomach Endoscopic ultrasound-guided fine needle aspiration Endosonography Case report

A Knowledge-enhanced Two-stage Generative Framework for Medical Dialogue Information Extraction

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Machine Intelligence Research 2024年第1期21卷 153-168页

作者： Zefa Hu Ziyi Ni Jing Shi Shuang xu bo xu School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100049China Institute of Automation Chinese Academy of SciencesBeijing 100190China

This paper focuses on term-status pair extraction from medical dialogues(MD-TSPE),which is essential in diagnosis dia-logue systems and the automatic scribe of electronic medical records(EMRs).In the past few years,works on MD-TSPE have attracted increasing research attention,especially after the remarkable progress made by generative methods.However,these generative methods output a whole sequence consisting of term-status pairs in one stage and ignore integrating prior knowledge,which demands a deeper un-derstanding to model the relationship between terms and infer the status of each term.This paper presents a knowledge-enhanced two-stage generative framework(KTGF)to address the above challenges.Using task-specific prompts,we employ a single model to com-plete the MD-TSPE through two phases in a unified generative form:We generate all terms the first and then generate the status of each generated term.In this way,the relationship between terms can be learned more effectively from the sequence containing only terms in the first phase,and our designed knowledge-enhanced prompt in the second phase can leverage the category and status candidates of the generated term for status generation.Furthermore,our proposed special status"not mentioned"makes more terms available and en-riches the training data in the second phase,which is critical in the low-resource setting.The experiments on the Chunyu and CMDD datasets show that the proposed method achieves superior results compared to the state-of-the-art models in the full training and low-re-sourcesettings.

关键词： Medical dialogue understanding information extraction text generation knowledge-enhanced prompt low-resource setting dataaugmentation

Effect of Texture on the Grain-Size-Dependent Functional Properties of NiTi Shape Memory Alloys and Texture Gradient Design:A Phase Field Study

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Acta Mechanica Solida Sinica 2024年第1期37卷 10-32页

作者： bo xu Beihai Huang Chong Wang Qingyuan Wang Failure Mechanics and Engineering Disaster Prevention Key Laboratory of Sichuan ProvinceSichuan UniversityChengdu 610065China Department of Mechanical Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Key Laboratory of Deep Underground Science and Engineering Ministry of EducationSichuan UniversityChengdu 610065China

Texture is inevitably introduced during the manufacturing of most NiTi shape memory alloys(SMAs),and the textured nanocrystalline NiTi has been extensively employed in engineering.However,the effect of texture,and the joint effect of grain size(GS)and texture on the functional properties of NiTi SMAs and the corresponding microscopic mechanisms have not been clearly understood yet.In this work,based on the phase field method,the effect of texture on the GS-dependent functional properties of NiTi SMAs,including super-elasticity(SE),one-way shape memory effect(OWSME),and stress-assisted two-way shape memory effect(SATWSME),is investigated,and the corresponding microscopic mechanisms are revealed.Moreover,the samples with discrete geometrical gradients and/or texture gradients are designed to achieve graded functional properties.The simulation results indicate that the dependence of functional properties on texture is due to the effect of crystallographic orientation on martensite transformation and reorientation,which can lead to different inelastic strains.In the designed samples with texture gradients,the stress–strain responses of sheets with various textures are different,allowing for the coordination of overall deformation of the sample by combining such sheets,with varying inelastic deformation degrees.Thus,the overall response of the sample differs from that without texture gradient,leading to the achievement of graded functional properties.The simulation results and new findings in this work contribute to a deeper understanding of the effects of texture,GS,and their interaction on the functional properties of SMAs,and provide valuable reference for the design and development of SMA-based devices with desired functional properties.

关键词： Phase field NiTi shape memory alloy Texture Grain size Functional property Texture gradient

Effects ofβ-1,3-glucan and ascorbic acid on the nutritional-immune response and antioxidant signaling pathways of live tiger grouper during simulated transport

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Aquaculture and Fisheries 2024年第2期9卷 265-272页

作者： bo Wu Zhenkun xu Jie Cao Qi Wang jun Mei Jing Xie College of Food Science and Technology Shanghai Ocean UniversityShanghai201306China National Experimental Teaching Demonstration Center for Food Science and Engineering Shanghai Ocean UniversityShanghai201306China Shanghai Engineering Research Center of Aquatic Product Processing and Preservation Shanghai201306China Shanghai Professional Technology Service Platform on Cold Chain Equipment Performance and Energy Saving Evaluation Shanghai201306China

Transport in water is the most common method for transporting live fish in China,however,transport is a strong stressor.Transport stress could lead to a reduced immune and antioxidant system function of tiger grouper,resulting in sickness and death.Besides,tiger grouper were continuously stressed during transport,which resulted in quality deterioration.It is necessary that find a way to relieve the stress of transportation of tiger grouper.Ascorbic acid is not only a good anti-stress agent,but it is also an effective immunostimulant.β-1,3-glucan is a feed additive that can enhance the immune response of fish.Therefore,this study evaluated the effects ofβ-1,3-glucan and ascorbic acid on the nutritional-immune response and antioxidant signaling pathways of live tiger grouper during simulated transport.Results indicated that addingβ-1,3-glucan and ascorbic acid in transport-water muted the increase of alanine aminotransferase(ALT)and aspartate aminotransferase(AST)activity.In addition,β-1,3-glucan and ascorbic acid activated Nrf2 and mediated TOR expression and then up-regulate related mRNA expression of antioxidant and immune enzymes.We concluded that the application ofβ-1,3-glucan and ascorbic acid inhibit the increase of metabolism enzymes and inflammatory factors and activate immune and antioxidant signaling pathways to relieve oxidant stress,immune response,and apoptosis.Reducing the loss of amino acids provided nutrients to relieve oxidative stress and immune response,which demonstrated immune-nutritional response in live tiger grouper during simulated transport.These results may provide a new solution for alleviating the decline of immune and antioxidant function of tiger grouper caused by transportation stress.

关键词： Tiger grouper β-1,3-Glucan Ascorbic acid Immune response Antioxidant signaling pathway

Identification and effective regulation of scarb1 gene involved in pigmentation change in autotetraploid Carassius auratus

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Zoological Research 2024年第2期45卷 381-397页

作者： Xi-Dan xu Yue Zhou Chong-Qing Wang xu Huang Kun Zhang Xiao-Wei xu Li-Wen He Xin-Yue Zhang Xin-Zhu Fu Ming Ma Qin-bo Qin Shao-jun Liu State Key Laboratory of Developmental Biology of Freshwater Fish Engineering Research Center of Polyploid Fish Reproduction and Breeding of the State Education MinistryCollege of Life SciencesHunan Normal UniversityChangshaHunan 410081China Nansha-South China Agricultural University Fishery Research Institute GuangzhouGuangdong 511458China Hunan Yuelu Mountain Science and Technology Co.Ltd.for Aquatic Breeding ChangshaHunan 410081China College of Chemistry and Chemical Engineering Hunan Normal UniversityChangshaHunan 410081China

The autotetraploid Carassius auratus(4nRR,4n=200,RRRR)is derived from whole-genome duplication of Carassius auratus red var.(RCC,2n=100,RR).In the current study,we demonstrated that chromatophores and pigment changes directly caused the coloration and variation of 4nRR skin(red in RCC,brownish-yellow in4nRR).To further explore the molecular mechanisms underlying coloration formation and variation in 4nRR,we performed transcriptome profiling and molecular functional verification in RCC and 4nRR.Results revealed that scarb1,associated with carotenoid metabolism,underwent significant down-regulation in 4nRR.Efficient editing of this candidate pigment gene provided clear evidence of its significant role in RCC coloration.Subsequently,we identified four divergent scarb1 homeologs in 4nRR:two original scarb1 homeologs from RCC and two duplicated ones.Notably,three of these homeologs possessed two highly conserved alleles,exhibiting biased and allelespecific expression in the skin.Remarkably,after precise editing of both the original and duplicated scarb1homeologs and/or alleles,4nRR individuals,whether singly or multiply mutated,displayed a transition from brownishyellow skin to a cyan-gray phenotype.Concurrently,the proportional areas of the cyan-gray regions displayed a gene-dose correlation.These findings illustrate the subfunctionalization of duplicated scarb1,with all scarb1genes synergistically and equally contributing to the pigmentation of 4nRR.This is the first report concerning the functional differentiation of duplicated homeologs in an autopolyploidfish,substantiallyenrichingour understanding of coloration formation and change within this group of organisms.

关键词： Autopolyploidization Coloration change scarb1 Functional differentiation Genetic changes

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A Rendezvous Mission to the Second Earth Trojan Asteroid 2020 XL_5 with Low-Thrust Multi-Gravity Assist Techniques

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Research in Astronomy and Astrophysics 2024年第1期24卷 245-264页

作者： Shi-Hai Yang bo xu Xin Li School of Aeronautics and Astronautics Sun Yat-sen UniversityShenzhen 518107China

As the second of Earth's Trojan asteroids, 2020 XL_(5) is worthy of rendezvous and even sample return missions in many aspects. In this paper, a rendezvous mission to Earth's second Trojan asteroid 2020 XL_(5) is proposed.However, due to its high inclination and large eccentricity, direct impulsive transfer requires large amounts of fuel consumption. To address this challenge, we explore the benefits of electric propulsion and multi-gravity assist techniques for interplanetary missions. These two techniques are integrated in this mission design. The design of a low-thrust gravity-assist(LTGA) trajectory in multi-body dynamics is thoroughly investigated,which is a complex process. A comprehensive framework including three steps is presented here for optimization of LTGA trajectories in multi-body dynamics. The rendezvous mission to 2020 XL_(5) is designed with this three-step approach. The most effective transfer sequence among the outcomes involves Earth–Venus–Earth–Venus-2020 XL_(5). Numerical results indicate that the combination of electric propulsion and multi-gravity assists can greatly reduce the fuel consumption, with fuel consumption of 9.03%, making it a highly favorable choice for this rendezvous mission.

关键词： minor planets asteroids:general celestial mechanics Planetary Systems

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