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Dynamic response of ultralight all-metallic sandwich panel with 3D tube cellular core to shallow-buried explosives

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Science China(Technological Sciences) 2021年第7期64卷 1371-1388页

作者： ZHANG duJiang ZHAO Zhen Yu du shaofeng CHEN WeiJie YANG Fan NI ChangYe YANG ZhiKun LU TianJian State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China MIIT Key Laboratory of Multifunctional Lightweight Materials and Structures(MLMS) Nanjing University of Aeronautics and AstronauticsNanjing210016China State Key Laboratory of Smart Manufacturing for Special Vehicles and Transmission System Baotou014030China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong UniversityXi’an710049China

The underbody of a vehicle system, either military or civil, is typically made of a relatively thin metallic plate, thus vulnerable to mine blast attacks. To improve the blast resistance, a multitude of protective structures have been proposed as attachments to the thin plate. In the present study, a novel ultralight all-metallic sandwich panel with three-dimensional(3D) tube cellular cores mounted to the vehicle underbody was envisioned as such a protective system. A metallic substrate(mimicking vehicle bottom)was placed above the proposed sandwich panel to construct a sandwich-substrate combinative structure. A series of sandwich panels having 3D tube cellular cores were fabricated via argon protected welding and laser welding. Mechanical responses of the combinative structure subjected to the denotation of 6 kg TNT explosives shallow-buried in dry sand were experimentally measured. Full numerical simulations with the method of finite elements(FE) were subsequently carried out to explore the physical mechanisms underlying the observed dynamic performance and quantify the effects of key geometrical parameters and connection conditions of the protective system. The performance of the proposed sandwich panel under shallow-buried explosives was also compared with competing sandwich constructions having equal mass. Finally, a preliminary optimal design of the 3D tube cellular core was carried out.

关键词： shallow-buried explosive sand blast test 3D tube cellular core sandwich panel numerical simulation

Programmable and reconfigurable humidity-driven actuators made with MXene(Ti_(3)C_(2)T_(x))-cellulose nanofiber composites for biomimetic applications

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Nano Research 2024年第7期17卷 6619-6629页

作者： shaofeng Zeng Yuanji Ye Peidi Zhou Shimin Yi Qiaohang Guo Huamin Chen Guozhen Shen Mingcen Weng School of Mechanical and Automotive Engineering Fujian University of TechnologyFuzhou 350118China School of Materials Science and Engineering Fujian Provincial Key Laboratory of Advanced Materials Processing and ApplicationKey Laboratory of Polymer Materials and Products of Universities in FujianFujian University of TechnologyFuzhou 350118China Institute of Smart Marine and Engineering Fujian University of TechnologyFuzhou 350118China Fujian Key Laboratory of Functional Marine Sensing Materials College of Materials and Chemical EngineeringMinjiang UniversityFuzhou 350108China School of Integrated Circuits and Electronics Beijing Institute of TechnologyBeijing 100081China

Smart actuators have a wide range of applications in bionics and energy *** ability to reconfigure shape is essential for soft actuators to achieve various shapes and deformations,which is a crucial feature for next-generation ***,it is still an enormous challenge to establish a straightforward approach to creating programmable and reconfigurable ***-cellulose nanofiber composite film(MCCF)with a brick-and-mortar hierarchical structure was produced through a vacuum filtration *** demonstrates impressive mechanical properties such as a tensile stress of 68 MPa and a Young’s modulus of 4.65 ***,the MCCF highlights its potential for water-assisted shaping/welding due to the abundance of hydrogen bonds between MXene and cellulose *** also showcases capabilities as a humiditydriven actuator with a rapid response rate of 550°·s^(−1).Using the methods of water-assisted shaping/welding,several bionic actuators(such as flower,butterfly,and muscle)based on MCCF were designed,highlighting their versatility in applications of smart *** research showcases the impressive capabilities of MXene-based actuators and offers beneficial insights for the advancement of future intelligent materials.

关键词： MXene cellulose nanofibers programmable actuators humidity-driven

A Practical Regular LDPC Coded Scheme for Physical-Layer Information Security

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China Communications 2024年第5期21卷 190-201页

作者： du Junyi CETC Key Laboratory of Avionic Information System Southwest China Institute of Electronic TechnologyChengdu 610036China

In this paper,we aim to design a practical low complexity low-density parity-check(LDPC)coded scheme to build a secure open channel and protect information from *** this end,we first propose a punctured LDPC coded scheme,where the information bits in a codeword are punctured and only the parity check bits are transmitted to the *** further propose a notion of check node type distribution and derive multi-edge type extrinsic information transfer functions to estimate the security performance,instead of the well-known weak metric bit error *** optimize the check node type distribution in terms of the signal-to-noise ratio(SNR)gap and modify the progressive edge growth algorithm to design finite-length *** results show that our proposed scheme can achieve a lower computational complexity and a smaller security gap,compared to the existing scrambling and puncturing schemes.

关键词： extrinsic information transfer function physical layer scheme secure open channel security gap

Boundary slip and lubrication mechanisms of organic friction modifiers with effect of surface moisture

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Friction 2024年第7期12卷 1483-1498页

作者： Xiaobin YI Haiyu XU Ge JIN Yang LU Biqiang CHEN shaofeng XU Junqin SHI Xiaoli FAN State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China Xi’an Thermal Power Research Institute Co. Ltd.Xi’an 710054China NingboTech University Ningbo 315000China

Surface moisture or humidity impacting the lubrication property is a ubiquitous phenomenon in tribological systems,which is demonstrated by a combination of molecular dynamics(MD)simulation and experiment for the organic friction modifier(OFM)-containing *** stearic acid and poly-α-olefin 4cSt(PAO4)were chosen as the OFM and base oil molecules,*** physical adsorption indicates that on the moist surface water molecules are preferentially adsorbed on friction surface,and even make OFM adsorption film thoroughly leave surface and mix with base *** shear process,the adsorption of water film and desorption OFM film are further enhanced,particularly under higher shear *** simulated friction coefficient(that is proportional to shear rate)increases firstly and then decreases with thickening water film,in good agreement with experiments,while the slip length shows a contrary *** wear increases with humidity due to tribochemistry revealing the continuous formation and removal of Si–O–Si *** tribological discrepancy of OFM-containing lubricant in dry and humid conditions is attributed to the slip plane’s transformation from the interface between OFM adsorption film and lubricant bulk to the interface between adsorbed water *** work provides a new thought to understand the boundary lubrication and failure of lubricant in humid environments,likely water is not always harmful in oil lubrication systems.

关键词： organic friction modifier(OFM) boundary lubrication boundary slip surface moisture

Transformer and GAN-Based Super-Resolution Reconstruction Network for Medical Images

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Tsinghua Science and Technology 2024年第1期29卷 197-206页

作者： Weizhi du Shihao Tian Arts&Sciences College Washington University in St.LouisSt.LouisMO 63130USA Department of Electric and Computing Engineering Cornell UniversityIthacaNY 14850USA

Super-resolution reconstruction in medical imaging has become more demanding due to the necessity of obtaining high-quality images with minimal radiation dose,such as in low-field magnetic resonance imaging(MRI).However,image super-resolution reconstruction remains a difficult task because of the complexity and high textual requirements for diagnosis *** this paper,we offer a deep learning based strategy for reconstructing medical images from low resolutions utilizing Transformer and generative adversarial networks(T-GANs).The integrated system can extract more precise texture information and focus more on important locations through global image matching after successfully inserting Transformer into the generative adversarial network for picture ***,we weighted the combination of content loss,adversarial loss,and adversarial feature loss as the final multi-task loss function during the training of our proposed model *** comparison to established measures like peak signal-to-noise ratio(PSNR)and structural similarity index measure(SSIM),our suggested T-GAN achieves optimal performance and recovers more texture features in super-resolution reconstruction of MRI scanned images of the knees and belly.

关键词： super-resolution image reconstruction Transformer generative adversarial network(GAN)

High-pressure minerals and new lunar mineral changesite-(Y) in Chang’e-5 regolith

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Matter and Radiation at Extremes 2024年第2期9卷 90-97页

作者： Jing Yang Wei du Center for Lunar and Planetary Sciences Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of Sciences(CAS)Guiyang 550081China CAS Center for Excellence in Comparative Planetology Hefei 230026China

Forty-five years after the Apollo and Luna missions, China’s Chang’e-5 (CE-5) mission collected ∼1.73 kg of new lunar materials from one ofthe youngest basalt units on the Moon. The CE-5 lunar samples provide opportunities to address some key scientific questions related to theMoon, including the discovery of high-pressure silica polymorphs (seifertite and stishovite) and a new lunar mineral, changesite-(Y). Seifertitewas found to be coexist with stishovite in a silica fragment from CE-5 lunar regolith. This is the first confirmed seifertite in returned lunarsamples. Seifertite has two space group symmetries (Pnc2 and Pbcn) and formed from an α-cristobalite-like phase during “cold” compressionduring a shock event. The aftershock heating process changes some seifertite to stishovite. Thus, this silica fragment records different stagesof an impact process, and the peak shock pressure is estimated to be ∼11 to 40 GPa, which is much lower than the pressure condition forcoexistence of seifertite and stishovite on the phase diagram. Changesite-(Y), with ideal formula (Ca_(8)Y)◻Fe^(2+)(PO_(4))_(7) (where ◻ denotes avacancy) is the first new lunar mineral to be discovered in CE-5 regolith samples. This newly identified phosphate mineral is in the form ofcolumnar crystals and was found in CE-5 basalt fragments. It contains high concentrations of Y and rare earth elements (REE), reaching upto ∼14 wt. % (Y,REE)2O3. The occurrence of changesite-(Y) marks the late-stage fractional crystallization processes of CE-5 basalts combinedwith silicate liquid immiscibility. These new findings demonstrate the significance of studies on high-pressure minerals in lunar materials andthe special nature of lunar magmatic evolution.

关键词： evolution minerals basalt

Physics-informed deep Koopman operator for Lagrangian dynamic systems

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Science China(Information Sciences) 2024年第9期67卷 146-163页

作者： Xuefeng WANG Yang CAO shaofeng CHEN Yu KANG Department of Automation University of Science and Technology of China State Key Laboratory of Fire Science University of Science and Technology of China Institute of Advanced Technology University of Science and Technology of China

Accurate mechanical system models are crucial for safe and stable control. Unlike linear systems,Lagrangian systems are highly nonlinear and difficult to optimize because of their unknown system *** research thus used deep neural networks to generate linear models of original systems by mapping nonlinear dynamic systems into a linear space with a Koopman observable function encoder. The controller then relies on the Koopman linear model. However, without physical information constraints, ensuring control consistency between the original nonlinear system and the Koopman system is tough, as the learning process of the Koopman observation function is unsupervised. This paper thus proposes a two-stage learning algorithm that uses structural subnetworks to build a physics-informed network topology to simultaneously learn the Koopman observable functions and the system energy representation. In the Koopman matrix learning session, a quadratic-constrained optimization problem is solved to ensure that the Koopman representation satisfies the energy difference matching hard constraint. The proposed energy-preserving deep Lagrangian Koopman(EPDLK) framework effectively represents the dynamics of the Lagrangian system while ensuring control consistency. The effectiveness of EPDLK is compared with those of various Koopman observable function construction methods in multistep prediction and trajectory tracking tasks. EPDLK achieves better control consistency by guaranteeing energy difference matching, which facilitates the application of the control law generated on the Koopman system directly to the original nonlinear Lagrangian system.

关键词： Koopman operator Lagrangian physics-informed nonlinear model predictive control (MPC)

Sequential Propagation of Chaos for Mean-Field BSDE Systems

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Chinese Annals of Mathematics,Series B 2024年第1期45卷 11-40页

作者： Xiaochen LI Kai du Shanghai Center for Mathematical Sciences Fudan UniversityShanghai 200433China. Shanghai Artificial Intelligence Laboratory 701 Yunjin RoadShanghai 200433China

A new class of backward particle systems with sequential interaction is proposed to approximate the mean-field backward stochastic differential *** is proven that the weighted empirical measure of this particle system converges to the law of the McKean-Vlasov system as the number of particles *** on the Wasserstein met-ric,quantitative propagation of chaos results are obtained for both linear and quadratic growth ***,numerical experiments are conducted to validate our theoretical results.

关键词： Backward propagation of chaos Particle system Sequential interaction McKean-Vlasov BSDE Convergence rate

In situ injectable hydrogel encapsulating Mn/NO-based immune nano-activator for prevention of postoperative tumor recurrence

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Asian Journal of Pharmaceutical Sciences 2024年第2期19卷 102-119页

作者： Shengnan Huang Chenyang Zhou Chengzhi Song Xiali Zhu Mingsan Miao Chunming Li shaofeng duan Yurong Hu Academy of Chinese Medical Sciences Henan University of Chinese MedicineZhengzhou 450046China School of Pharmaceutical Sciences Henan Key Laboratory of Targeting Therapy and Diagnosis for Critical DiseasesZhengzhou UniversityZhengzhou 450001China Center for Quantitative Biology Peking UniversityBeijing 100871China School of Pharmaceutical Sciences Henan University of Chinese MedicineZhengzhou 450046China Department of Pharmacy Chongqing University Cancer HospitalChongqing 400030China School of Pharmaceutical Sciences Henan UniversityZhengzhou 450046China

Postoperative tumor recurrence remains a predominant cause of treatment failure. In this study, we developed an in situ injectable hydrogel, termed MPB-NO@DOX + ATRA gel, which was locally formed within the tumor resection cavity. The MPB-NO@DOX + ATRA gel was fabricated by mixing a thrombin solution, a fibrinogen solution containing all-trans retinoic acid (ATRA), and a Mn/NO-based immune nano-activator termed MPB-NO@DOX. ATRA promoted the differentiation of cancer stem cells, inhibited cancer cell migration, and affected the polarization of tumor-associated macrophages. The outer MnO2 shell disintegrated due to its reaction with glutathione and hydrogen peroxide in the cytoplasm to release Mn2+ and produce O2, resulting in the release of doxorubicin (DOX). The released DOX entered the nucleus and destroyed DNA, and the fragmented DNA cooperated with Mn2+ to activate the cGAS-STING pathway and stimulate an anti-tumor immune response. In addition, when MPB-NO@DOX was exposed to 808 nm laser irradiation, the Fe-NO bond was broken to release NO, which downregulated the expression of PD-L1 on the surface of tumor cells and reversed the immunosuppressive tumor microenvironment. In conclusion, the MPB-NO@DOX + ATRA gel exhibited excellent anti-tumor efficacy. The results of this study demonstrated the great potential of in situ injectable hydrogels in preventing postoperative tumor recurrence.

关键词： Post-sur gical tumor recurrence In situl hydrogel Immunotherapy Tumor micr oenvir onment Manganese(Ⅱ) Nitic oxide