期刊文献+
共找到897篇文章
< 1 2 45 >
每页显示 20 50 100
Experimental Investigation on the Mechanical Properties of Silicone Elastomers Filled with Fumed Silica for Seismic Isolation Bearings
1
作者 Arthur Ramandalina Ji Dang 《Journal of Building Material Science》 2025年第1期44-61,共18页
Laminated elastomeric bearings used in seismic isolation rely on the mechanical properties of their constituent elastomers to ensure effective performance.However,despite their resistance to temperature fluctuations a... Laminated elastomeric bearings used in seismic isolation rely on the mechanical properties of their constituent elastomers to ensure effective performance.However,despite their resistance to temperature fluctuations and environmental aggressors,silicone elastomers exhibit relatively low stiffness,limiting their direct applicability in seismic isolation.This study investigates the effect of fumed silica as a reinforcing filler to enhance the mechanical properties of laminated silicone elastomeric bearings.Elastomeric samples were fabricated with varying fumed silica proportions and subjected to Shore A hardness,uniaxial tensile,and lap shear tests to assess the influence of filler content.Additionally,quasi-static tests were conducted on reduced-scale bearing prototypes under combined vertical compression and cyclic horizontal shear to evaluate their seismic isolation performance.The results demonstrate that fumed silica reinforcement significantly increases stiffness,as evidenced by higher Shore A hardness values.However,a trade-off was observed in tensile properties,with reductions in tensile strength and elongation at break.Despite this,the equivalent elastic modulus did not show substantial variation up to large deformations,indicating that stiffness is preserved under most working conditions.Lap shear tests showed that fumed silica improves shear resistance,while quasi-static tests revealed inelastic behavior with small increases in equivalent shear coefficients but no substantial loss in damping ratios.These findings suggest that fumed silica reinforcement enhances silicone elastomers’stiffness and shear resistance while maintaining moderate damping properties,making it a promising approach for improving the mechanical performance of elastomeric bearings in seismic isolation applications. 展开更多
关键词 Silicone Elastomer Fumed Silica Elastomeric Bearing Seismic Isolation Experimental Study
在线阅读 下载PDF
Pd-catalyzed enantioselective and regioselective asymmetric hydrophosphorylation and hydrophosphinylation of enynes
2
作者 Yanxin Jiang Kwai Wun Cheng +1 位作者 Zhiping Yang Jun(Joelle)Wang 《Chinese Chemical Letters》 2025年第5期231-236,共6页
The chemo-,regio-,and enantio-controlled synthesis of P-chiral phosphines in a general and efficient manner remains a significant synthetic challenge.In this study,a Pd-catalyzed hydrofunctionalization is developed fo... The chemo-,regio-,and enantio-controlled synthesis of P-chiral phosphines in a general and efficient manner remains a significant synthetic challenge.In this study,a Pd-catalyzed hydrofunctionalization is developed for the highly selective synthesis of P-stereogenic alkenylphosphinates and alkenylphosphine oxides via conjugate addition of enynes.Notably,this methodology is suitable for both phosphine oxide and phosphinate nucleophiles,providing a versatile approach for the construction of diverse P-chiral organophosphosphorus compound. 展开更多
关键词 Phosphine ENYNE Pd catalyst P-chirality Asymmetric catalysis
原文传递
Nonlinear Reconstruction of 21cm Global Signal from 21cm Power Spectrum with Artificial Neural Networks
3
作者 Hayato Shimabukuro 《Research in Astronomy and Astrophysics》 2025年第8期180-192,共13页
In this paper, we propose a novel method using artificial neural networks(ANNs) to reconstruct the global 21 cm signal from measurements of the 21 cm power spectrum. The 21 cm global signal provides crucial informatio... In this paper, we propose a novel method using artificial neural networks(ANNs) to reconstruct the global 21 cm signal from measurements of the 21 cm power spectrum. The 21 cm global signal provides crucial information on cosmic evolution from the Dark Ages through cosmic dawn and the Epoch of Reionization. Single-dish telescopes directly measure the global signal, whereas interferometric experiments primarily measure spatial fluctuations,represented by the 21 cm power spectrum. While no direct mathematical relationship exists between these two observables-since they probe fundamentally independent Fourier modes-they are indirectly linked through their common dependence on underlying astrophysical and cosmological parameters. The ANN effectively learns this implicit, model-dependent relationship, enabling it to predict the global signal from the power spectrum. We demonstrate that the ANN accurately recovers the global 21 cm signal across a broad redshift range(z = 7.5–35)even under realistic observational noise scenarios corresponding to SKA-1 observations. The reconstruction accuracy depends significantly on the spatial scales(wavenumber k) included, with larger-scale modes yielding better results due to their stronger sensitivity to global astrophysical processes. Although the ANN method does not provide a model-independent verification of anomalous observations(e.g., the Experiment to Detect the Global Epoch of Reionization Signature absorption trough), it offers a computationally efficient and robust tool to infer the global signal within the context of standard astrophysical and cosmological models. 展开更多
关键词 (cosmology:)dark ages REIONIZATION frst stars cosmology:theory (cosmology:)diffuse radiation
在线阅读 下载PDF
A comparative study of prey-handling behavior of the Chiwen keelback snake(Rhabdophis chiwen)feeding on earthworms and firefly larvae
4
作者 Masaya Fukuda Qin Chen +1 位作者 Chengquan Cao Akira Mori 《Current Zoology》 2025年第5期573-580,共8页
Dietary specialists consume specific prey items,and they are often morphologically and behaviorally specialized to feed efficiently on those prey animals.Among specialist snakes,consumption of terrestrial arthropods i... Dietary specialists consume specific prey items,and they are often morphologically and behaviorally specialized to feed efficiently on those prey animals.Among specialist snakes,consumption of terrestrial arthropods is relatively rare.Because most terrestrial arthropods possess hardened sclerites and appendages,it is possible that snakes that feed on arthropods would show specialized prey-handling behavior.In this study,we describe prey-handling behavior of a snake feeding on terrestrial arthropods,which hitherto has not been well documented.We focused on Rhabdophis chiwen,which mainly feeds on earthworms,but also consumes lampyrine firefly larvae,sequestering cardiotonic steroids from them in its defensive organs,called nucho-dorsal glands.When feeding on earthworms,snakes showed size-dependent selection of swallowing direction,but this tendency was not observed when feeding on firefly larvae.Manipulation of firefly larvae did not seem to be efficient,probably because they possess sclerites and appendages such as legs that impede smooth handling.Although fireflies are an essential food for R.chiwen as a toxin source,our results showed that the snake is not adept at handling firefly larvae compared to earthworms,implying that dietary specialization does not necessarily accompany behavioral specialization.We discuss possible reasons for this inconsistency. 展开更多
关键词 BEHAVIOR EARTHWORM FIREFLY prey-handling Rhabdophis
原文传递
Effects of targeted deletion of a 284 bp avian-specific highly conserved element within the Sim1 gene on flight feather development in chickens
5
作者 Keiji Kinoshita Kumiko Tanabe +6 位作者 Muhammad Ameen Jamal Momoko Kyu-Shin Kai-Xiang Xu Yan-Hua Su Xiong Zhang Takayuki Suzuki Hong-Jiang Wei 《Zoological Research》 2025年第3期608-617,共10页
Flight feathers represent a hallmark innovation of avian evolution.Recent comparative genomic analyses identified a 284 bp avian-specific highly conserved element(ASHCE)located within the eighth intron of the SIM bHLH... Flight feathers represent a hallmark innovation of avian evolution.Recent comparative genomic analyses identified a 284 bp avian-specific highly conserved element(ASHCE)located within the eighth intron of the SIM bHLH transcription factor 1(Sim1)gene,postulated to act as a cis-regulatory element governing flight feather morphogenesis.To investigate its functional significance,genome-edited(GE)primordial germ cell(PGC)lines carrying targeted ASHCE deletions were generated using CRISPR/Cas9-mediated editing,with germline chimeric males subsequently mated with wild-type(WT)hens to obtain GE progeny.The resulting GE chickens harbored 257-260 bp deletions,excising approximately half of the Sim1-ASHCE sequence.Reverse transcription-quantitative real-time polymerase chain reaction(RT-qPCR)analysis showed an average 0.32-fold reduction in Sim1 expression in the forelimbs of GE embryos at day 8(E8)compared to WT counterparts.Despite this,GE chickens developed structurally normal flight and tail feathers.In situ hybridization localized Sim1 expression to the posterior mesenchyme surrounding flight feather buds in E8 WT embryos,but not within the buds themselves.These results suggest that partial deletion of Sim1-ASHCE,despite diminishing Sim1 expression,does not disrupt flight feather formation.The excised region appears to possess enhancer activity toward Sim1 but is dispensable for flight feather development.Complete ablation of the ASHCE will be necessary to fully resolve the regulatory role of Sim1 in avian feather morphogenesis. 展开更多
关键词 Sim1 gene Avian-specific enhancer Flight feather development Primordial germ cell Genome editing
在线阅读 下载PDF
Mouse model of anti-RANKL discontinuation reveals reduced bone mass and quality through disruption of bone remodeling
6
作者 Koji Ishikawa Soji Tani +8 位作者 Nobuhiro Sakai Yoshifumi Kudo Hideyo Horiuchi Hiromi Kimura-Suda Masamichi Takami Mayumi Tsuji Katsunori Inagaki Yuji Kiuchi Takako Negishi-Koga 《Bone Research》 2025年第4期1001-1014,共14页
The discontinuation of denosumab[antibody targeting receptor activator of nuclear factor kappa B ligand(RANKL)]therapy may increase the risk of multiple vertebral fractures;however,the underlying pathophysiology is la... The discontinuation of denosumab[antibody targeting receptor activator of nuclear factor kappa B ligand(RANKL)]therapy may increase the risk of multiple vertebral fractures;however,the underlying pathophysiology is largely unknown.In patients who underwent discontinuation after multiple injections of denosumab,the levels of tartrate-resistant acid phosphatase 5b increased compared to pretreatment levels,indicating a phenomenon known as“overshoot.”The rate of decrease in bone mineral density during the withdrawal period was higher than the rate of decrease associated with aging,suggesting that the physiological bone metabolism had broken down.Overshoot and significant bone loss were also observed in mice receiving continuous administration of anti-RANKL antibody after treatment was interrupted,resembling the original pathology.In mice long out of overshoot,bone resorption recovered,but osteoblast numbers and bone formation remained markedly reduced.The bone marrow exhibited a significant reduction in stem cell(SC)antigen 1-and platelet-derived growth factor receptor alpha-expressing osteoblast progenitors(PαS cells)and alkaline phosphatase-positive early osteoblasts.Just before the overshoot phase,the osteoclast precursor cell population expands and RANKL-bearing extracellular vesicles(EVs)became abundant in the serum,leading to robust osteoclastogenesis after cessation of anti-RANKL treatment.Thus,accelerated bone resorption due to the accumulation of RANKLbearing EVs and long-term suppression of bone formation uncoupled from bone resorption leads to the severe bone loss characteristic of denosumab discontinuation. 展开更多
关键词 vertebral fractureshoweverthe decrease bone mineral density bone mass tartrate resistant acid phosphatase b mouse model anti RANKL discontinuation bone remodeling bone quality
暂未订购
Analysis software for upper atmospheric data developed by the IUGONET project and its application to polar science 被引量:2
7
作者 Yoshimasa Tanaka Atsuki Shinbori +9 位作者 Tomoaki Hori Yukinobu Koyama Shuji Abe No-rio Umemura Yuka Sato Manabu Yagi Satoru UeNo Akiyo Yatagai Yasunobu Ogawa Yoshizumi Miyoshi 《Advances in Polar Science》 2013年第4期231-240,共10页
To comprehensively understand the Arctic and Antarctic upper atmosphere, it is often crucial to analyze various data that are obtained from many regions. Infrastructure that promotes such interdisciplinary studies on ... To comprehensively understand the Arctic and Antarctic upper atmosphere, it is often crucial to analyze various data that are obtained from many regions. Infrastructure that promotes such interdisciplinary studies on the upper atmosphere has been developed by a Japanese inter-university project called the Inter-university Upper atmosphere Global Observation Network (1UGONET). The objective of this paper is to describe the infrastructure and tools developed by IUGONET. We focus on the data analysis software. It is written in Interactive Data Language (IDL) and is a plug-in for the THEMIS Data Analysis Software suite (TDAS), which is a set of IDL libraries used to visualize and analyze satellite- and ground-based data. We present plots of upper atmospheric data provided by IUGONET as examples of applications, and verify the usefulness of the software in the study of polar science. We discuss IUGONET's new and unique developments, i.e., an executable file of TDAS that can run on the IDL Virtual Machine, IDL routines to retrieve metadata from the IUGONET database, and an archive of 3-D simulation data that uses the Common Data Format so that it can easily be used with TDAS. 展开更多
关键词 data analysis software metadata database upper atmosphere ground-based observation polar science interdisciplinary study IUGONET
在线阅读 下载PDF
Fabrication of amorphous FeCoNiCuMnP x high-entropy phosphide/carbon composites with a heterostructured fusiform morphology for efficient oxygen evolution reaction 被引量:3
8
作者 Yifan Zhou Longqing Gao +5 位作者 Haoyuan Chen Hao Wang Juan Zhang Xiumin Li Fangfang Duo Guoqing Guan 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2024年第1期62-70,共9页
Amorphous high-entropy materials with abundant defects,coordinatively unsaturated sites,and loosely bonded atoms could exhibit excellent electrocatalytic performance.However,how to fabricate such ma-terials with nanos... Amorphous high-entropy materials with abundant defects,coordinatively unsaturated sites,and loosely bonded atoms could exhibit excellent electrocatalytic performance.However,how to fabricate such ma-terials with nanostructure as well as amorphous structure is still full of challenges.In this work,high-entropy metal organic framework(HE-MOF)is employed as the self-sacrificial template to fabricate FeCoNiCuMnP x high-entropy phosphide/carbon(HEP/C)composites.The obtained composite shows a het-erostructured fusiform morphology,in which the HEP is encapsulated by a carbon layer,revealing high electron conductivity as well as rich catalytic active sites for oxygen evolution reaction(OER).Beside,it is found that there is a short-range ordered crystal structure in the amorphous phase,which is bene-ficial for revealing high OER catalytic activity as well as good stability.As a result,the optimum HEP/C composite shows an overpotential 239 mV@10 mA cm^(−2)with a small Tafel slope of 72.5 mV dec^(−1) for catalyzing OER in alkaline solution. 展开更多
关键词 Water electrolysis Oxygen evolution reaction High-entropy MOFs High-entropy phosphides Amorphous structure
原文传递
Evolution and Prospects of Foundation Models: From Large Language Models to Large Multimodal Models 被引量:3
9
作者 Zheyi Chen Liuchang Xu +5 位作者 Hongting Zheng Luyao Chen Amr Tolba Liang Zhao Keping Yu Hailin Feng 《Computers, Materials & Continua》 SCIE EI 2024年第8期1753-1808,共56页
Since the 1950s,when the Turing Test was introduced,there has been notable progress in machine language intelligence.Language modeling,crucial for AI development,has evolved from statistical to neural models over the ... Since the 1950s,when the Turing Test was introduced,there has been notable progress in machine language intelligence.Language modeling,crucial for AI development,has evolved from statistical to neural models over the last two decades.Recently,transformer-based Pre-trained Language Models(PLM)have excelled in Natural Language Processing(NLP)tasks by leveraging large-scale training corpora.Increasing the scale of these models enhances performance significantly,introducing abilities like context learning that smaller models lack.The advancement in Large Language Models,exemplified by the development of ChatGPT,has made significant impacts both academically and industrially,capturing widespread societal interest.This survey provides an overview of the development and prospects from Large Language Models(LLM)to Large Multimodal Models(LMM).It first discusses the contributions and technological advancements of LLMs in the field of natural language processing,especially in text generation and language understanding.Then,it turns to the discussion of LMMs,which integrates various data modalities such as text,images,and sound,demonstrating advanced capabilities in understanding and generating cross-modal content,paving new pathways for the adaptability and flexibility of AI systems.Finally,the survey highlights the prospects of LMMs in terms of technological development and application potential,while also pointing out challenges in data integration,cross-modal understanding accuracy,providing a comprehensive perspective on the latest developments in this field. 展开更多
关键词 Artificial intelligence large language models large multimodal models foundation models
在线阅读 下载PDF
Quantitative analysis of microstructure evolution,stress partitioning and thermodynamics in the dynamic transformation of Fe-14Ni alloy 被引量:3
10
作者 Lian Li Goro Miyamoto +5 位作者 Yongjie Zhang Miaoquan Li Satoshi Morooka Katsunari Oikawa Yo Tomota Tadashi Furuhara 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2024年第17期221-234,共14页
Dynamic transformation(DT)of austenite(γ)to ferrite(α)in the hot deformation of various carbon steels was widely investigated.However,the nature of DT remains unclear due to the lack of quantitative analysis of stre... Dynamic transformation(DT)of austenite(γ)to ferrite(α)in the hot deformation of various carbon steels was widely investigated.However,the nature of DT remains unclear due to the lack of quantitative analysis of stress partitioning between two phases and the uncertainty of local distribution of substitu-tional elements at the interface in multi-component carbon steels used in the previous studies.Therefore,in the present study,a binary Fe-Ni alloy withα+γduplex microstructure in equilibrium was prepared and isothermally compressed inα+γtwo-phase region to achieve a quantitative analysis of microstruc-ture evolution,stress partitioning,and thermodynamics during DT.γtoαDT during isothermal compres-sion andαtoγreverse transformation on isothermal annealing under unloaded condition after deforma-tion were accompanied by Ni partitioning.The lattice strains during thermomechanical processing were obtained via in-situ neutron diffraction measurement,based on which the stress partitioning behavior betweenγandαwas discussed by using the generalized Hooke’s law.A thermodynamic framework for the isothermal deformation in solids was established based on the basic laws of thermodynamics,and it was shown that the total Helmholtz free energy change in the deformable material during the isothermal process should be smaller than the work done to the deformable material.Under the present thermody-namic framework,the microstructure evolution in the isothermal compression of Fe-14Ni alloy was well explained by considering the changes in chemical free energy,plastic and elastic energies,and the work done to the material.In addition,the stabilization of the softαphase in Fe-14Ni alloy by deformation was rationalized since theγtoαtransformation decreased the total Helmholtz free energy by decreasing the elastic and dislocation energies. 展开更多
关键词 Iron Nickel Dynamic transformation Isothermal deformation Stress partitioning Neutron diffraction THERMODYNAMICS
原文传递
Geomorphological evidence inconvenient for the antecedent rivers of the Arun and Tista across the Himalayan range 被引量:1
11
作者 NAKATA Takashi KUMAHARA Yasuhiro +1 位作者 NAIK Sambit Prasanajit SAKAI Harutaka 《Journal of Mountain Science》 SCIE CSCD 2024年第9期3001-3017,共17页
The Arun and Tista Rivers,which flow across the Himalayas,are commonly known as antecedent valleys that overcame the rapid uplift of the Higher Himalayan ranges.To clarify whether the idea of antecedent rivers is acce... The Arun and Tista Rivers,which flow across the Himalayas,are commonly known as antecedent valleys that overcame the rapid uplift of the Higher Himalayan ranges.To clarify whether the idea of antecedent rivers is acceptable,we investigated the geomorphology of the Himalayas between eastern Nepal and Bhutan Himalayas.The southern part of Tibetan Plateau,extending across the Himalayas as tectonically un-deformed glaciated terrain named as'Tibetan Corridor,'does not suggest the regional uplift of the Higher Himalayas.The 8,000-m class mountains of Everest,Makalu,and Kanchenjunga are isolated residual peaks on the glaciated terrain composed of mountain peaks of 4,000–6,000 m high.The Tibetan glaciers commonly beheaded by Himalayan glaciers along the great watershed of the Himalayas suggest the expansion of Himalayan river drainage by glaciation.For the narrow upstream regions of the Arun and Tista Rivers with less precipitation behind the range,it is hard to collect enough water for the power of down-cutting their channels against the uplifting Himalayas.The fission track ages of the Higher Himalayan Crystalline Nappe suggest that the Himalayas attained their present altitude by 11–10 Ma,and the Arun and Tista Rivers formed deep gorges across the Himalayas by headward erosion. 展开更多
关键词 HIMALAYA Antecedent river Geomorphology AW3D30 DSM Glacier piracy
原文传递
Effects of multimodal microstructure on fracture toughness and its anisotropy of LPSO-type extruded Mg-1Zn-2Y alloys 被引量:1
12
作者 Soya Nishimoto Taiga Yasuda +1 位作者 Koji Hagihara Michiaki Yamasaki 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第7期2952-2966,共15页
The fracture toughness of extruded Mg-1Zn-2Y(at.%)alloys,featuring a multimodal microstructure containing fine dynamically recrystallized(DRXed)grains with random crystallographic orientation and coarse-worked grains ... The fracture toughness of extruded Mg-1Zn-2Y(at.%)alloys,featuring a multimodal microstructure containing fine dynamically recrystallized(DRXed)grains with random crystallographic orientation and coarse-worked grains with a strong fiber texture,was investigated.The DRXed grains comprised randomly oriented equiaxedα-Mg grains.In contrast,the worked grains includedα-Mg and long-period stacking ordered(LPSO)phases that extended in the extrusion direction(ED).Both types displayed a strong texture,aligning the(10.10)direction parallel to the ED.The volume fractions of the DRXed and worked grains were controlled by adjusting the extrusion temperature.In the longitudinal-transverse(L-T)orientation,where the loading direction was aligned parallel to the ED,there was a tendency for the conditional fracture toughness,KQ,tended to increase as the volume fraction of the worked grains increased.However,the KQ values in the T-L orientation,where the loading direction was perpendicular to the ED,decreased with an increase in the volume fraction of the worked grains.This suggests strong anisotropy in the fracture toughness of the specimen with a high volume fraction of the worked grains,relative to the test direction.The worked grains,which included the LPSO phase and were elongated perpendicular to the initial crack plane,suppressed the straight crack extension,causing crack deflection,and generating secondary cracks.Thus,these worked grains significantly contributed to the fracture toughness of the extruded Mg-1Zn-2Y alloys in the L-T orientation. 展开更多
关键词 Magnesium alloy Magnesium-zinc-yttrium Long-period stacking ordered phase Multimodal microstructure Fracture toughness
在线阅读 下载PDF
Flow Patterns and Heat Transfer Characteristics of a Polymer Pulsating Heat Pipe Filled with Hydrofluoroether 被引量:1
13
作者 Nobuhito Nagasato Zhengyuan Pei Yasushi Koito 《Frontiers in Heat and Mass Transfer》 EI 2024年第1期49-63,共15页
Visualization experiments were conducted to clarify the operational characteristics of a polymer pulsating heat pipe(PHP).Hydrofluoroether(HFE)-7100 was used as a working fluid,and its filling ratio was 50%of the enti... Visualization experiments were conducted to clarify the operational characteristics of a polymer pulsating heat pipe(PHP).Hydrofluoroether(HFE)-7100 was used as a working fluid,and its filling ratio was 50%of the entire PHP channel.A semi-transparent PHP was fabricated using a transparent polycarbonate sheet and a plastic 3D printer,and the movements of liquid slugs and vapor plugs of the working fluid were captured with a high-speed camera.The video images were then analyzed to obtain the flow patterns in the PHP.The heat transfer characteristics of the PHPwere discussed based on the flowpatterns and temperature distributions obtainedwith thermocouples.Before starting heating,because of high wettability,large liquid slugs positioned at the evaporator section of the PHP.After starting heating,since the occurrence of boiling divided the large liquid slugs,oscillatory flowof smaller liquid slugs and vapor plugs was found in the PHP.Clear circulation flow of liquid slugs and vapor plugs was observed when the power input to the PHP was larger than 12.0 W.The flow patterns and temperature distributions confirmed that the circulation flow enhanced the heat transfer from the evaporator section to the condenser section of the PHP.In the circulation flow mode,large growth and contraction of vapor plugs were found one after another in all even-numbered PHP channels.However,the analysis of flow patterns clarified that the phase-change heat transfer rate by large growth and contraction of vapor plugs was 19%of the total heat transfer rate of the PHP.Although the generation of large vapor plugs was found in the PHP,most of the heat was transferred by the sensible heat of the working fluid. 展开更多
关键词 Polymer heat pipe VISUALIZATION oscillatory flow circulation flow thermal management 3D printer
在线阅读 下载PDF
High performance micromachining of sapphire by laser induced plasma assisted ablation(LIPAA)using GHz burst mode femtosecond pulses 被引量:1
14
作者 Kotaro Obata Shota Kawabata +2 位作者 Yasutaka Hanada Godai Miyaji Koji Sugioka 《Opto-Electronic Science》 2024年第6期20-29,共10页
GHz burst-mode femtosecond(fs)laser,which emits a series of pulse trains with extremely short intervals of several hundred picoseconds,provides distinct characteristics in materials processing as compared with the con... GHz burst-mode femtosecond(fs)laser,which emits a series of pulse trains with extremely short intervals of several hundred picoseconds,provides distinct characteristics in materials processing as compared with the conventional irradiation scheme of fs laser(single-pulse mode).In this paper,we take advantage of the moderate pulse interval of 205 ps(4.88 GHz)in the burst pulse for high-quality and high-efficiency micromachining of single crystalline sapphire by laser induced plasma assisted ablation(LIPAA).Specifically,the preceding pulses in the burst generate plasma by ablation of copper placed behind the sapphire substrate,which interacts with the subsequent pulses to induce ablation at the rear surface of sapphire substrates.As a result,not only the ablation quality but also the ablation efficiency and the fabrication resolution are greatly improved compared to the other schemes including single-pulse mode fs laser direct ablation,single-pulse mode fs-LIPAA,and nanosecond-LIPAA. 展开更多
关键词 femtosecond laser GHz burst mode ablation LIPAA laser induced plasma assisted ablation SAPPHIRE
在线阅读 下载PDF
Effects of heterogeneous microstructure evolution on the tensile and fracture toughness properties of extruded AZ31B alloys 被引量:1
15
作者 ShengXiong Tang Soya Nishimoto +1 位作者 Koji Hagihara Michiaki Yamasaki 《Journal of Magnesium and Alloys》 CSCD 2024年第10期4126-4139,共14页
This study aims to investigate the extrusion temperature effects on the development of heterogeneous microstructures and mechanical properties,focusing on their impact on the fracture toughness of AZ31B alloys.Magnesi... This study aims to investigate the extrusion temperature effects on the development of heterogeneous microstructures and mechanical properties,focusing on their impact on the fracture toughness of AZ31B alloys.Magnesium AZ31B(Mg-3wt%Al-1wt%Zn)alloys with high strength and reasonable fracture toughness,featuring heterogeneous microstructures,were fabricated via warm/hot extrusion at temperatures ranging from 523 to 723 K.The AZ31B alloy extruded at 523 K was bimodally grained into coarse worked grains with high Kernel average misorientation(KAM)values and fine dynamically recrystallized(DRXed)grains(<10μm)with intermediate KAM values.The 523 K-extruded alloy exhibited a high tensile yield strength of∼280 MPa and fracture toughness KJIC of∼26 MPa·m^(1/2).Conversely,the 723 K-extruded AZ31B alloy was trimodally grained into a small amount of worked grains,fine DRXed grains,and coarse DRXed grains(>10μm)with low KAM values.The 723 K-extruded alloy exhibited low tensile yield strength but a high KJIC value of∼36 MPa·m^(1/2)owing to the high energy dissipation for crack extension in the coarse DRXed grains. 展开更多
关键词 Magnesium alloy AZ31B Tensile property Fracture toughness Bimodal/trimodal microstructure
在线阅读 下载PDF
Liquefaction and post-liquefaction behaviors of sands affected by immersion-induced degradation of crushed mudstone
16
作者 Tadao Enomoto 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第5期1799-1812,共14页
A series of undrained triaxial tests was conducted to investigate the effect of crushed mudstone with the immersion-induced degradation on the liquefaction and post-liquefaction properties,and the undrained shearing b... A series of undrained triaxial tests was conducted to investigate the effect of crushed mudstone with the immersion-induced degradation on the liquefaction and post-liquefaction properties,and the undrained shearing behavior without precedent cyclic-loading histories of sands containing crushed mudstone.The tested materials with a main particle diameter of 2-0.85 mm were prepared by mixing sands and crushed mudstone to reach the prescribed mudstone content defined by dry mass ranging from 0% to 50%.The mixtures were subjected to immersion under a certain stress level and were subsequently tested.In addition,one-dimensional compression tests were also supplementally performed to visually observe the immersion-induced degradation of crushed mudstone.The test results mainly showed that: (1) the liquefaction resistance,the post-liquefaction undrained strength,and the undrained strength without a precedent cyclic-loading history decreased significantly with increasing mudstone content,M c ,up to 20%;(2) even a small amount of crushed mudstone affected these strengths;(3) the above-mentioned large reductions in the strengths were attributed to the immersion-induced degradation of crushed mudstone;(4) at M_(c) >20%,the liquefaction resistance increased while the significant increase in the undrained static strengths with and without precedent cyclic-loading histories was not observed;and (5) the increase in the liquefaction resistance at M_(c) >20% may have been attributed to both the gradual increase in the plasticity and the formation of the soil aggregates among deteriorated crushed mudstone,while the increase in the specimen density did not play an important role in such behavior. 展开更多
关键词 LIQUEFACTION Post-liquefaction behavior Triaxial test Sands containing crushed mudstone
在线阅读 下载PDF
Oxidation behavior and improvement in nonflammability of LPSO-type Mg–Zn–Y–Sr alloy
17
作者 Shin-ichi Inoue Kazumasa Iwanaga Yoshihito Kawamura 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第2期742-749,共8页
Mg_(97)Zn_(1)Y_(2)alloys with high ignition temperatures were developed by adding Sr.The addition of Sr resulted in the formation of a uniform and thin Y_(2)O_(3)film.Mg–Zn–Y alloys containing at least 0.25 at.%Sr e... Mg_(97)Zn_(1)Y_(2)alloys with high ignition temperatures were developed by adding Sr.The addition of Sr resulted in the formation of a uniform and thin Y_(2)O_(3)film.Mg–Zn–Y alloys containing at least 0.25 at.%Sr exhibited ignition temperatures of 1270–1320 K.As a result of EDS measurement,Sr was found to be concentrated in the Y_(2)O_(3)film.In addition,a mixed film of MgO and Sr O formed on the outer layer in the 1.5 at.%Sr-containing Mg_(97)Zn_(1)Y_(2)alloy.These findings suggest that the uniform and thin Y_(2)O_(3)film that maintains high soundness at high temperatures was formed owing to valence control and the formation of a protective outer oxide film. 展开更多
关键词 Magnesium alloy YTTRIUM STRONTIUM High-temperature oxidation Nonflammability
在线阅读 下载PDF
Improving Prediction Efficiency of Machine Learning Models for Cardiovascular Disease in IoST-Based Systems through Hyperparameter Optimization
18
作者 Tajim Md.Niamat Ullah Akhund Waleed M.Al-Nuwaiser 《Computers, Materials & Continua》 SCIE EI 2024年第9期3485-3506,共22页
This study explores the impact of hyperparameter optimization on machine learning models for predicting cardiovascular disease using data from an IoST(Internet of Sensing Things)device.Ten distinct machine learning ap... This study explores the impact of hyperparameter optimization on machine learning models for predicting cardiovascular disease using data from an IoST(Internet of Sensing Things)device.Ten distinct machine learning approaches were implemented and systematically evaluated before and after hyperparameter tuning.Significant improvements were observed across various models,with SVM and Neural Networks consistently showing enhanced performance metrics such as F1-Score,recall,and precision.The study underscores the critical role of tailored hyperparameter tuning in optimizing these models,revealing diverse outcomes among algorithms.Decision Trees and Random Forests exhibited stable performance throughout the evaluation.While enhancing accuracy,hyperparameter optimization also led to increased execution time.Visual representations and comprehensive results support the findings,confirming the hypothesis that optimizing parameters can effectively enhance predictive capabilities in cardiovascular disease.This research contributes to advancing the understanding and application of machine learning in healthcare,particularly in improving predictive accuracy for cardiovascular disease management and intervention strategies. 展开更多
关键词 Internet of sensing things(IoST) machine learning hyperparameter optimization cardiovascular disease prediction execution time analysis performance analysis wilcoxon signed-rank test
在线阅读 下载PDF
上一页 1 2 45 下一页 到第
使用帮助 返回顶部