检索结果-南通市图书馆

Chinese Journal of Mechanical Engineering 2024年第1期37卷 203-214页

作者： Xiaokang Huang Xiaoyong Tian Qi Zhong Shunwen He Cunbao Huo Yi Cao Zhiqiang Tong Dichen Li state Key Laboratory of Manufacturing Systems Engineering Xi’an Jiaotong UniversityXian 710049China

Improvement of fabrication efficiency and part performance was the main challenge for the large-scale powder bed fusion(PBF)*** this study,a dynamic monitoring and feedback system of powder bed temperature field using an infrared thermal imager has been established and integrated into a four-laser PBF equipment with a working area of 2000 mm×2000 *** heat-affected zone(HAZ)temperature field has been controlled by adjusting the scanning speed ***,the relationship among spot size,HAZ temperature,and part performance has been *** fluctuation of the HAZ temperature in four-laser scanning areas was decreased from 30.85℃to 17.41℃.Thus,the consistency of the sintering performance of the produced large component has been *** on the controllable temperature field,a dynamically adjusting strategy for laser spot size was proposed,by which the fabrication efficiency was improved up to 65.38%.The current research results were of great significance to the further industrial applications of large-scale PBF equipment.

关键词： Powder bed fusion Efficiency Large-scale Spot size Heat-affected zone(HAZ)

New steelmaking process based on clean deoxidation technology

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1249-1262页

作者： Zhongliang Wang Yanping Bao state Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

After the converter steelmaking process,a considerable number of ferroalloys are needed to remove dissolved oxygen from the molten steel,but it also forms a lot of oxide inclusions that cannot be completely *** the same time,it increases the carbon emis-sions in the steel production *** years of research,our team have developed a series of clean deoxidation technologies,includ-ing carbon deoxidation,hydrogen deoxidation,and waste plastic deoxidation of molten steel to address the aforementioned *** this study,thermodynamic calculations and laboratory experiments were employed to verify that carbon and hydrogen can reduce the total oxygen content in the molten steel melt to below 5×10^(-6) and 10×10^(-6),*** analysis of the deoxidation mechanisms and ef-fects of polyethylene and polypropylene was also *** addition,the applications of carbon deoxidation technology in different steels with the hot-state experiment and industrial production were discussed *** carbon deoxidation experimental results of different steels were as follows:(1)the oxygen content of bearing steel was effectively controlled at 6.3×10^(-6) and the inclusion number density was lowered by 74.73%compared to aluminum deoxidized bearing steel;(2)the oxygen content in gear steel was reduced to 7.7×10^(-6) and a 54.49%reduction of inclusion number density was achieved with almost no inclusions larger than 5μm from the average level of industry gear steels;(3)a total oxygen content of M2 high-speed steel was as low as 3.7×10^(-6).In industrial production practice,car-bon deoxidation technique was applied in the final deoxidation stage for non-aluminum deoxidized bearing steel,and it yielded excellent results that the oxygen content was reduced to below 8×10^(-6) and the oxide inclusions in the steel mainly consist of silicates,along with small amounts of spinel and calcium aluminate.

关键词： clean deoxidation carbon deoxidation hydrogen deoxidation waste plastics deoxidation

Process in laser drilling of deep microholes without taper on metal materials

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第1期67卷 37-59页

作者： FAN RunZe MEI XueSong CUI JianLei state Key Laboratory for Manufacturing Systems Engineering Xi’an Jiaotong UniversityXi’an 710054China

Deep microhole machining is currently a prominent research area within the aerospace field,encompassing blade film cooling and fuel injection control ***,taper defects in metal materials may lead to performance degradation or even structural damage over a component’s *** and helical drilling,facilitated by ultrashort pulse lasers,have proven more suitable for achieving high-precision,deep holes in metal ***,excessive repetition rates can also result in severe thermal *** methods are commonly employed for controlling taper,including parameter optimization,assistance,and secondary *** laser beam drilling is widely utilized and has been integrated into relevant machining systems for commercial *** deep microholes include film cooling holes and injection *** drilling is a potential machining method for new materials in the aerospace *** laser drilling processing has been studied,numerous related scientific challenges and technical difficulties must be addressed before practical implementation.

关键词： aerospace laser drilling deep microhole taper control

Systematical High-Pressure Study of Praseodymium Nitrides in N-Rich Region

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2024年第6期41卷 67-87页

作者：刘冉刘爽张盈王鹏姚震 state Key Laboratory of Superhard Materials College of PhysicsJilin UniversityChangchun 130012China

We investigate high-pressure phase diagrams of Pr–N compounds by proposing five stable structures(PnmaPr N,Ⅰ4/mmm-PrN_(2),C2/m-PrN_(3),P■-PrN_(4),and R3-PrN_(8))and two metastable structures(P■-PrN_(6)and P■-PrN_(10)).The P■-PrN_(6)with the N14-ring layer and R3-PrN_(8)with the N18-ring layer can be quenched to ambient *** the P■-PrN_(10),the N_(22)-ring layer structure transfers into infinite chains with the pressure quenched to ambient ***,a novel polynitrogen h R8-N designed by the excision of Pr atoms from R3-PrN_(8)is obtained and can be quenched to ambient *** N-rich structures of P■-PrN_(6),R3-PrN_(8),c-PrN_(10)and the solid pure nitrogen structure exhibit outstanding properties of energy density and explosive performance.

关键词： ambient structure layer

Quasi-three-dimensional hydrodynamics of the corona region of laser irradiation of a slab

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第8期33卷 351-360页

作者：董晓梅关本金李英骏 state Key Laboratory for Tunnel Engineering China University of Mining and TechnologyBeijing 100083China

This paper introduces and establishes a quasi-three-dimensional physical model of the interaction between a laser and a slab *** contrast to previous one-dimensional analytical models,this paper innovatively fits the real laser conditions based on an isothermal,homogeneous expansion similarity solution of the ideal hydrodynamic *** this simple model,the evolution law and analytical formulae for key parameters(e.g.,temperature,density and scale length)in the corona region under certain conditions are *** analytical solutions agree well with the relevant results of computational hydrodynamics *** constant laser irradiation,the analytical solutions provide a meaningful power-law scaling *** model provides a set of mathematical and physical tools that give theoretical support for adjusting parameters in experiments.

关键词： plasma self-similarity method fluid dynamics calculations

Mitigate noisy data for smart IoT via GAN based machine unlearning

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第3期67卷 62-78页

作者： Zhuo MA Yilong YANG Yang LIU Xinjing LIU Jianfeng MA School of Cyber Engineering Xidian University state Key Laboratory of Integrated Services Networks (ISN)

With the development of IoT applications, machine learning dramatically improves the utility of variable IoT systems such as autonomous driving. Although the pretrain-finetune framework can cope well with data heterogeneity in complex IoT scenarios, the data collected by sensors often contain unexpected noisy data, e.g., out-of-distribution(OOD) data, which leads to the reduced performance of fine-tuned models. To resolve the problem, this paper proposes Mu GAN, a method that can mitigate the side-effect of OOD data via the generative adversarial network(GAN)-based machine unlearning. Mu GAN follows a straightforward but effective idea to mitigate the performance loss caused by OOD data, i.e., “flashbacking” the model to the condition where OOD data are excluded from model training. To achieve the goal, we design an adversarial game, where a discriminator is trained to identify whether a sample belongs to the training set by observing the confidence score. Meanwhile, a generator(i.e., the target model) is updated to fool the discriminator into believing that the OOD data are not included in the training set but others do. The experimental results show that benefiting from the high unlearning rate(more than 90%) and retention rate(99%), Mu GAN succeeds in lowering the model performance degradation caused by OOD data from 5.88% to 0.8%.

关键词： machine unlearning generative adversarial network out of distribution data Internet of Thing neural network

同方期刊数据库

Effect of Al_(2)O_(3)/SiO_(2) mass ratio and CaO content on viscosity and structure of slag for pyrometallurgical processing of spent automotive catalysts

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2024年第3期31卷 608-621页

作者： Zhe Wang Qi-long Wei Cheng-bin Shi Zhan-cheng Guo state Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

The effect of Al_(2)O_(3)/SiO_(2) mass ratio and CaO content on the viscosity and structure of the CaO-Al_(2)O_(3)-SiO_(2)-6MgO-1.5ZrO_(2)-1.5CeO_(2) slag was *** results show that with the increase in Al_(2)O_(3)/SiO_(2) mass ratio,the viscous flow units within the slag gradually change from Si-O-Si to Al-O-Al and ***,the substitution of Al_(2)O_(3) for SiO_(2) leads to the transformation of Si-O bonds towards weaker Al-O bonds,which weaken the bond strength of the aluminosilicate networks,thus leading to a decrease in the viscosity of *** increase in CaO content effectively promotes the depolymerization of the aluminosilicate networks,resulting in a significant decrease in the viscosity of the *** slag with Al_(2)O_(3)/SiO_(2) of 0.7-1.5 and CaO of 30 wt.%shows promise as the reference slag system for the Fe-collection smelting of spent automotive catalysts due to its good comprehensive performance.

关键词： Aluminosilicate slag Al_(2)O_(3)/SiO_(2)mass ratio CaO content Viscosity Slag structure

Simulation of roof snow loads based on a multi-layer snowmelt model:Impact of building heat transfer

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Building Simulation 2024年第6期17卷 907-932页

作者： Xuanyi Zhou Heng Chen Yue Wu Tiange Zhang state Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghai200092China

To investigate the impact of building heat transfer on roof snow loads,roof snow loads and snow load thermal coefficients from 61 Chinese sites over a period of 50 years are simulated based on basic meteorological data such as temperature,humidity,wind speed,and precipitation,and a multi-layer snowmelt model considering the building heat ***,the accuracy of the multi-layer snowmelt model is validated using the data of observed ground snow load and roof snow melting *** relationship between meteorological conditions,snow cover characteristics,and thermal coefficients of snow loads in three representative sites is then ***,the characteristics of thermal coefficients in each zone are analyzed by combining them with the statistical results of meteorological data from 1960 to 2010,and the equations of thermal coefficients in different zones on indoor temperatures and roof heat transfer coefficients are fitted ***,the equations in this paper are compared with the thermal coefficients in the main snow load *** results indicate that the snowmelt model using basic meteorological data can effectively provide samples of roof snow *** the cold zone where the snow cover lasts for a long time and does not melt easily,the thermal coefficients of the snow loads on the heating buildings are lower than those in the warm zone due to the long-term influence of the heat from inside the *** coefficients are negatively correlated with indoor temperatures and roof heat transfer *** the indoor temperature is too low or the roof insulation is good,the roof snow load may exceed the ground snow *** thermal coefficients for heated buildings in the main snow load codes are more conservative than those calculated in this paper,and the thermal coefficients for buildings with lower indoor temperatures tend to be smaller.

关键词： snowmelt model roof snow load building heat transfer thermal coefficient load code

Building a domain-specific compiler for emerging processors with a reusable approach

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第1期67卷 20-38页

作者： Mingzhen LI Yi LIU Bangduo CHEN Hailong YANG Zhongzhi LUAN Depei QIAN state Key Laboratory of Software Development Environment School of Computer Science and Engineering Beihang University

High-performance computing and deep learning domains have been motivating the design of domain-specific *** these processors can provide promising computation capability,they are notorious for exotic programming *** improve programming productivity and fully exploit the performance potential of these processors,domain-specific compilers(DSCs) have been ***,building DSCs for emerging processors requires tremendous engineering efforts because the commonly used compilation stack is difficult to be *** to the advent of multilevel intermediate representation(MLIR),DSC developers can leverage reusable infrastructure to extend their customized functionalities without rebuilding the entire compilation *** this paper,we further demonstrate the effectiveness of MLIR by extending its reusable infrastructure to embrace a heterogeneous many-core processor(Sunway processor).In particular,we design a new Sunway dialect and corresponding backend for the Sunway processor,fully exploiting its architectural advantage and hiding its programming *** show the ease of building a DSC,we leverage the Sunway dialect and existing MLIR dialects to build a stencil compiler for the Sunway *** experimental results show that our stencil compiler,built with a reusable approach,can even perform better than state-of-the-art stencil compilers.

关键词： domain-specific compiler emerging processor reusable dialect performance optimization MLIR

Advancing mid-infrared microdisk laser emission with Tm:YAG

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 91-96页

作者： Zhaocong Wang Huiqi Li Lei Wang Yang Tan Feng Chen School of Physics State Key Laboratory of Crystal MaterialsShandong UniversityJinan 250100China

Mid-infrared microcavity lasers have important applications in biosensing,mid-infrared spectroscopy,and environmental ***,the low output power of existing mid-infrared microcavity lasers hinders their practical *** drawback is attributed to the insufficient laser gain medium,which limits the development of mid-infrared whispering-gallerymode(WGM)*** address this issue,we have employed ion implantation-enhanced etching to fabricate Tm:YAG thin films as effective gain media for mid-infrared WGM *** Tm:YAG thin film,with a thickness of 2μm,exhibits excellent fluorescence ***,the Tm:YAG thin film is processed using focused ion beam to form microdisks with a diameter of 30μ*** 785 nm laser pumping,the maximum output power of the Tm:YAG microdisk at 2023.1 nm is229μW,with a slope efficiency of 2.9%.This work demonstrates the outstanding potential of Tm:YAG as a mid-infrared laser gain medium,providing a new option for the development of mid-infrared lasers.

关键词： microdisk microlaser ultrathin film