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High-thermal free vibration analysis of functionally graded microplates using a new finite element formulation based on TSDT and MSCT

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Defence Technology(防务技术) 2025年第2期44卷 131-149页

作者： Huu Trong Dang Nhan Thinh Hoang Quoc Hoa Pham Trung Thanh tran Huy Gia Luong Faculty of Mechanical Engineering Technology Vinh Long University of Technology EducationVinh Long 91000Viet Nam Institute for Creative Design and Business Nguyen Tat Thanh UniversityHo Chi Minh City 70000Viet Nam Faculty of Engineering and Technology Nguyen Tat Thanh UniversityHo Chi Minh City 70000Viet Nam Faculty of Mechanical Engineering Le Quy Don Technical UniversityHanoi 10000Viet Nam TechnoStar Vietnam TechnoStar Co.LtdHo Chi Minh City 70000Viet Nam

Recent advancements in additive manufacturing(AM)have revolutionized the design and production of complex engineering *** these advancements,their mathematical modeling and computational analysis remain significant *** research aims to develop an effective computational method for analyzing the free vibration of functionally graded(FG)microplates under high temperatures while resting on a Pasternak foundation(PF).This formulation leverages a new thirdorder shear deformation theory(new TSDT)for improved accuracy without requiring shear correction ***,the modified couple stress theory(MCST)is incorporated to account for sizedependent effects in *** PF is characterized by two parameters including spring stiffness(k_(w))and shear layer stiffness(k_(s)).To validate the proposed method,the results obtained are compared with those of the existing ***,numerical examples explore the influence of various factors on the high-temperature free vibration of FG *** factors include the length scale parameter(l),geometric dimensions,material properties,and the presence of the elastic *** findings significantly enhance our comprehension of the free vibration of FG microplates in high thermal *** addition,the findings significantly enhance our comprehension of the free vibration of FG microplates in high thermal *** addition,the results of this research will have great potential in military and defense applications such as components of submarines,fighter aircraft,and missiles.

关键词： Microplates Functionally graded material Finite element method Modified couple stress theory New TSDT High-thermal free vibration Pasternak foundation

Sub-stand diameter distribution types vary along an old-growth Douglas-fir chronosequence into the horizontal diversification development stage

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Journal of Forestry Research 2023年第2期34卷 415-424页

作者： JeriLynn E.Peck eric k.Zenner Department of Ecosystem Science and Management The Pennsylvania State UniversityUniversity ParkPA 16802USA

Managing mature Douglas-fir[Pseudotsuga menziesii(Mirb.)Franco]stands to emulate the structural complexity of natural old-growth forest requires identifying structural targets at the sub-stand level at which neighborhood dynamics and patchy disturbance shape *** therefore sought to describe the archetypal shapes of predominant sub-stand diameter distribution types(DDTs)observed in natural tree neighborhoods in stands comprising a chronosequence(ca.120-450+yrs)encompassing mature,vertical diversification,and horizontal diversification development *** ten 1.0 ha stands are located in the southcentral Oregon Cascades,*** on the known spatial position of each tree,natural tree neighborhoods were identified using the floating neighborhood approach based on spatial tessellation connecting neighboring trees at the first-(mean 61 m2)through fifth-(mean 2058 m2)order *** analysis was then used to objectively identify the most predominant DDTs among the relative tree size distributions observed in the trans-scale neighborhoods within each *** measures regression was used to classify each DDT to one of six observed archetypal shapes:negative exponential,unimodal,rotated sigmoid,bimodal,concave,or *** three of the 81 observed DDTs deviated by50%(maximum 83%).Within each stand,five to ten predominant DDTs were observed,which deviated from the stand average by 30-48%and were characterized by two to five different archetypal ***,in some stands the majority of tree neighborhoods were best characterized by a different shape from that assigned at the stand *** from the stand average increased from the youngest stand in the mature development stage through the middle stands in the vertical diversification stage to the oldest stands in the horizontal diversification *** complexity of DDT shapes tended to increas

关键词： Diameter distribution type Floating neighborhood Restoration silviculture Small-scale Structural complexity

Comparative impact behaviours of ultra high performance concrete columns reinforced with polypropylene vs steel fibres

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Defence Technology（防务技术） 2024年第10期40卷 138-153页

作者： Thong M.Pham Harrison Hyde Maw k.kaung Yan Zhuge Duong T.tran Des Vlietstra Tung M.tran UniSA STEMUniversity of South AustraliaMawson LakesSA 5095Australia BG&E Pty Ltd Wellington StreetPerthWA6000Australia Austral Construction Pty Ltd St Georges TerracePerthWA6000Australia Centre for Infrastructural Monitoring and Protection(CIMP) Curtin UniversityKent StBentleyWA 6102Australia Barchip Australia Pty Ltd U 26 Qualtroughq StreetWoolloongabbaQueensland4102Australia Sustainable Developments in Civil Engineering Research Group Faculty of Civil EngineeringTon Duc Thang UniversityHo Chi Minh City72915Viet Nam

Polypropylene(PP) fibres have primarily used to control shrinkage cracks or mitigate explosive spalling in concrete structures exposed to fire or subjected to impact/blast loads, with limited investigations on capacity improvement. This study unveils the possibility of using PP micro-fibres to improve the impact behaviour of fibre-reinforced ultra-high-performance concrete(FRUHPC) columns. Results show that the addition of fibres significantly improves the impact behaviour of FRUHPC columns by shifting the failure mechanism from brittle shear to favourable flexural failure. The addition of steel or PP fibres affected the impact responses differently. Steel fibres considerably increased the peak impact force(up to 18%) while PP micro-fibres slightly increased the peak(3%-4%). FRUHPC significantly reduced the maximum midheight displacement by up to 30%(under 20°impact) and substantially improved the displacement recovery by up to 100%(under 20° impact). FRUHPC with steel fibres significantly improved the energy absorption while those with PP micro-fibres reduced the energy absorption, which is different from the effect of PP-macro fibre reported in the literature. The optimal fibre content for micro-PP fibres is 1% due to its minimal fibre usage and low peak and residual displacement. This study highlights the potential of FRUHPC as a promising material for impact-resistant structures by creating a more favourable flexural failure mechanism, enhancing ductility and toughness under impact loading, and advancing the understanding of the role of fibres in structural performance.

关键词： Ultra high-performance concrete Steel fibre Polypropylene micro-fibre Fibre volume fraction Impact loading Pendulum tests Columns

Simulation of the overtaking maneuver between two ships using the non-linear maneuvering model

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Journal of Hydrodynamics 2018年第5期30卷 791-802页

作者： Peng Du A. Ouahsine k. T. tran p. Sergent Laboratoire Roberval UMR-CNRS 7337 Sorbonne Universites Universite de Technology de Compiegne Centre de Recherches Royallieu CS 60319 60203 Compiegne cedex France Cerema-134 Rue de Beauvais CS 60039 60200 Compiegne cedex France

The overtaking maneuver of two Esso Bernicia 1.9×10^5 DWT tankers was investigated using the system-based maneuvering method. The Brix model was incorporated to account for the overtaking interactions. Forces/moment acting on the ship hulls and maneuvering motions were analyzed for both ships during the overtaking. The influences of the speed ratio and the passing distance were specially studied. Two fitting formulas for the minimum distance during the overtaking were finally established as functions of the two factors respectively. They can be used to predict the minimum distance during an overtaking maneuver under similar conditions to avoid marine accidents.

关键词： Ship-to-ship interaction maneuvering overtaking draught yaw

Toward managing mixed-species stands： from parametrization to prescription

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Forest Ecosystems 2017年第4期4卷 286-302页

作者： Hans Pretzsch eric k. Zenner Chair for Forest Growth and Yield Science Center of Life and Food Sciences Weihenstephan Technical University of Munich Hans-Carl-von Carlowitz-Platz 2 85354 Freising Germany

A better understanding and a more quantitative design of mixed-species stands will contribute to more integrative and goal-oriented research in mixed-species forests. Much recent work has indicated that the structure and growth of mixed species forests may fundamentally differ from monocultures. Here we suggest how to progress from the present accumulation of phenomenological findings to a design of mixed-species stands and advanced silvicultural prescriptions by means of modelling. First, the knowledge of mixing effects on the structure and growth at the stand, species, and individual tree level is reviewed, with a focus on those findings that are most essential for suitable modelling and silvicultural designs and the regulation of mixed stands as opposed to monocultures. Then, the key role of growth models, stand simulators, and scenario assessments for designing mixed species stands is discussed The next section illustrates that existing forest stand growth models require some fundamental modifications to become suitable for both monocultures and mixed-species stands. We then explore how silvicultural prescriptions derived from scenario runs would need to be both quantified and simplified for transfer to forest management and demonstrated in training plots. Finally, we address the main remaining knowledge gaps that could be remedied through empirical research.

关键词： Multiplicative mixing effects Overyielding Overdensity Modelling mixing effects Scenario analysis,Silvicultural prescriptions Practical guidelines

Remote sensing and geographic information systems techniques in studies on treeline ecotone dynamics

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Journal of Forestry Research 2019年第5期30卷 1543-1553页

作者： Parveen k.Chhetri eric Thai Department of Earth Science and Geography California State University Dominguez Hills

We performed a meta-analysis on over 100 studies applying remote sensing(RS)and geographic information systems(GIS)to understand treeline dynamics.A literature search was performed in multiple online databases,including Web of knowledge(Thomson Reuters),Scopus(Elsevier),BASE(Bielefeld Academic Search Engine),CAB Direct,and Google Scholar using treeline-related *** found that RS and GIS use has steadily increased in treeline studies since *** RS and satellite imaging techniques varied from low-resolution MODIS,moderate-resolution Landsat,to high-resolution WorldView and aerial *** papers published in the 1990s used low to moderate resolution sensors such as Landsat Multispectral Scanner and Thematic Mapper,or SPOT PAN(Panchromatic)and MX(Multispectral)RS ***,we observed a rise in high-resolution satellite sensors such as ALOS,GeoEye,IkONOS,and WorldView for mapping current and potential ***,we noticed a shift in emphasis of treeline studies over time:earlier reports focused on mapping treeline positions,whereas RS and GIS are now used to determine the factors that control treeline variation.

关键词： Digital elevation model Geographic information systems Remote sensing Treeline

αβ T cell receptors as predictors of health and disease

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Cellular & Molecular Immunology 2015年第4期12卷 391-399页

作者： Meriem Attaf eric Huseby Andrew k Sewell Cardiff University School of Medicine Cardiff UK and ZDepartment of Pathology University of Massachusetts Medical School Worcester MA USA Correspondence: Professor AK Sewell Division of Infection and Immunity Cardiff University School of Medicine Henry Wellcome Building University Hospital Wales Cardiff CF14 4XN UK.

The diversity of antigen receptors and the specificity it underlies are the hallmarks of the cellular arm of the adaptive immune system. T and B lymphocytes are indeed truly unique in their ability to generate receptors capable of recognizing virtually any pathogen. It has been known for several decades that T lymphocytes recognize short peptides derived from degraded proteins presented by major histocompatibility complex （MHC） molecules at the cell surface. Interaction between peptide-MHC （pMHC） and the T cell receptor （TCR） is central to both thymic selection and peripheral antigen recognition. It is widely assumed that TCR diversity is required, or at least highly desirable, to provide sufficient immune coverage. However, a number of immune responses are associated with the selection of predictable, narrow, or skewed repertoires and public TCR chains. Here, we summarize the current knowledge on the formation of the TCR repertoire and its maintenance in health and disease. We also outline the various molecular mechanisms that govern the composition of the pre-selection, naive and antigen-specific TCR repertoires. Finally, we suggest that with the development of high-throughput sequencing, common TCR ＇signatures＇ raised against specific antigens could provide important diagnostic biomarkers and surrogate predictors of disease onset, progression and outcome.

关键词： T cell receptor (TCR) TCR repertoire TCR diversity TCR clonotype TCR bias Deep sequencing

Epigenetics and transgenerational inheritance in domesticated farm animals

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Journal of Animal Science and Biotechnology 2015年第2期6卷 123-129页

作者： Amanda Feeney eric Nilsson Michael k Skinner Center for Reproductive Biology School of Biological Sciences Washington State University

Epigenetics provides a molecular mechanism of inheritance that is not solely dependent on DNA sequence and that can account for non-Mendelian inheritance patterns. Epigenetic changes underlie many normal developmental processes, and can lead to disease development as well. While epigenetic effects have been studied in well-characterized rodent models, less research has been done using agriculturally important domestic animal species. This review will present the results of current epigenetic research using farm animal models （cattle, pigs, sheep and chickens）. Much of the work has focused on the epigenetic effects that environmental exposures to toxicants, nutrients and infectious agents has on either the exposed animals themselves or on their direct offspring. Only one porcine study examined epigenetic transgenerational effects; namely the effect diet micronutrients fed to male pigs has on liver DNA methylation and muscle mass in grand-offspring （F2 generation）. Healthy viable offspring are very important in the farm and husbandry industry and epigenetic differences can be associated with production traits. Therefore further epigenetic research into domestic animal health and how exposure to toxicants or nutritional changes affects future generations is imperative.

关键词： Environment EDiclenetics Pig. Review transgenerational

Gas permeability,diffusivity,and solubility in polymers:Simulation-experiment data fusion and multi-task machine learning

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npj Computational Materials 2024年第1期10卷 1327-1337页

作者： Brandon k.Phan kuan-Hsuan Shen Rishi Gurnani Huan tran Ryan Lively Rampi Ramprasad School of Materials Science and Engineering Georgia Institute of TechnologyAtlantaGAUSA School of Chemical and Biomolecular Engineering Georgia Institute of TechnologyAtlantaGAUSA

Machine learning(ML)models for predicting gas permeability through polymers have traditionally relied on experimental *** these models exhibit robustness within familiar chemical domains,reliability wanes when applied to new *** address this challenge,we present a multi-tiered multi-task learning framework empowered with advanced machine-crafted polymer fingerprinting algorithms and data fusion techniques.

关键词： solubility polymers learning