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Understanding the Rayleigh instability in humping phenomenon during laser powder bed fusion process

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International Journal of Extreme Manufacturing 2022年第1期4卷 85-92页

作者： Wenxuan Zhang Wenyuan Hou Luc Deike Craig Arnold Department of Chemical and Biological Engineering Princeton UniversityPrincetonNJ 08544United States of America princeton Institute for the Science and Technology of Materials Princeton UniversityPrincetonNJ 08544United States of America Department of Mechanical and Aerospace Engineering Princeton UniversityPrincetonNJ 08544United States of America High Meadows Environmental Institute Princeton UniversityPrincetonNJ 08544United States of America

The periodic undulation of a molten track’s height profile in laser-based powder bed fusion of metals(PBF-LB/M)is a commonly observed phenomena that can cause defects and building failure during the manufacturing *** a quantitative analysis of such instabilities has not been fully established and so here we used Rayleigh–Plateau theory to determine the stability of a single molten track in PBF-LB/M and tested it with various processing conditions by changing laser power and beam *** analysis discovered that normalized enthalpy,which relates to energy input density,determines whether a molten track is initially unstable and if so,the growth rate for the ***,whether the growth rate ultimately yields significant undulation depends on the melt duration,estimated by dwell time in our experiment.

关键词： additive manufacturing powder bed fusion dual lasers undulation humping

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Single-lens dynamic z-scanning for simultaneous in situ position detection and laser processing focus control

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Light(Science & Applications) 2023年第12期12卷 2655-2667页

作者： Xiaohan Du Camilo Florian Craig B.Arnold Department of Mechanical and Aerospace Engineering Princeton UniversityPrincetonNJ 08544USA Department of Systems Engineering City University of Hong KongHong KongChina Institut für Werkstofftechnik Universität Kassel34125 KasselGermany princeton Materials Institute Princeton UniversityPrincetonNJ 08544USA

Existing auto-focusing methods in laser processing typically include two independent modules,one for surface detection and another for z-axis *** latter is mostly implemented by mechanical z stage motion,which is up to three orders of magnitude slower than the lateral processing *** alleviate this processing bottleneck,we developed a single-lens approach,using only one high-speed z-scanning optical element,to accomplish both in situ surface detection and focus control quasi-simultaneously in a dual-beam *** probing beam scans the surface along the z-axis continuously,and its reflection is detected by a set of confocal *** on the temporal response of the detected signal,we have developed and experimentally demonstrated a dynamic surface detection method at 140-350 kHz,with a controlled detection range,high repeatability,and minimum linearity error of 1.10%.Sequentially,by synchronizing at a corresponding oscillation phase of the z-scanning lens,the fabrication beam is directed to the probed z position for precise focus ***,our approach provides instantaneous surface tracking by collecting position information and executing focal control both at 140-350 kHz,which significantly accelerates the axial alignment process and offers great potential for enhancing the speed of advanced manufacturing processes in three-dimensional space.

关键词： dynamic beam simultaneous

Cold snap for cancer:cold-induced brown fat thermogenesis starves tumor growth

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Signal Transduction and Targeted Therapy 2023年第2期8卷 329-330页

作者： Ziqing Chen Yibin Kang Department of Molecular Biology Princeton UniversityPrincetonNJ08544USA Ludwig Institute for Cancer Research princeton Branch PrincetonNJ08544USA

In a recent study published in Nature,Seki et *** that cold-induced brown fat activation impedes glycolysis and reduces tumor growth in multiple cancers,1 deepening our understanding of the complex role of fat metabol... 详细信息

关键词： metabolism deepening

What would a US green hydrogen energy economy look like?

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Clean Energy 2023年第5期7卷 1148-1172页

作者： Thomas Tonon Independent researcher Ph.D.Aerospace and Mechanical SciencesPrinceton University1971.11 Bolfmar AvenuePrinceton JunctionNJ 08550USA

Detailed description is given for a hypothetical US hydrogen economy with solar and wind energy supplying virtually all current energy needs and with electrolytic hydrogen the energy carrier and storage *** fuels provide nonfuel products(plastics,chemicals,cement and asphalt).Only current technologies are considered and hydrogen storage accommodates generation intermit-tency and variability,using pit storage of high-pressure vessels in open air,yielding daily storage round-trip energy installation costs of 722 and 538$/kWh for electric and thermal,respectively;and for power,2351 and 2240$/kW for electric and thermal,*** long-duration storage,the costs are 94.1 and 23.8$/kWh and 937 and 845$/kW,*** energy generation 20%over baseline accommodates low-season generation,obviates much required storage and ensures that reserves are topped off;96%of US 2022 total energy consumption is provided *** the default scenario(demand energy portions:half photovoltaic,quarter on-shore wind and quarter offshore wind),the surface area for the farms(including offshore surface)requires~4.6%of the US 48-state land *** 350 pit storage sites provide both daily and long-duration storage,with the latter accounting for complete loss of generation for 4 days over a quarter of the *** pipelines and a renewed electric grid transmit and distribute *** installation cost of the public infrastructure is~$27.8 trillion for the default *** scenarios show significant in-frastructure and cost savings when batteries are used for transportation and/or utility storage,provided current insufficiencies can be ***,cost levels in money,surface and infrastructure are within existing levels already achieved in historical events and modern living.

关键词： hydrogen economy renewable energy hydrogen storage hydrogen pipelines sustainable net zero

An Overview of Antiviral Peptides and Rational Biodesign Considerations

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BioDesign Research 2022年第1期2022卷 276-294页

作者： Ying-Chiang J.Lee Jaden D.Shirkey Jongbeom Park Karishma Bisht Alexis J.Cowan Department of Molecular Biology Princeton UniversityPrincetonNew Jersey 08544USA

Viral diseases have contributed significantly to worldwide morbidity and mortality throughout *** the existence of therapeutic treatments for many viral infections,antiviral resistance and the threat posed by novel viruses highlight the need for an increased number of effective *** addition to small molecule drugs and biologics,antimicrobial peptides(AMPs)represent an emerging class of potential antiviral *** AMPs have traditionally been regarded in the context of their antibacterial activities,many AMPs are now known to be *** antiviral peptides(AVPs)have been shown to target and perturb viral membrane envelopes and inhibit various stages of the viral life cycle,from preattachment inhibition through viral release from infected host *** design of AMPs has also proven effective in identifying highly active and specific peptides and can aid in the discovery of lead peptides with high therapeutic *** this review,we highlight AVPs with strong antiviral activity largely curated from a publicly available AMP *** then compile the sequences present in our AVP database to generate structural predictions of generic AVP ***,we cover the rational design approaches available for AVPs taking into account approaches currently used for the rational design of AMPs.

关键词： Rational drugs rational

Fragile topological band in the checkerboard antiferromagnetic monolayer FeSe

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npj Computational Materials 2022年第1期8卷 218-222页

作者： Aiyun Luo Zhida Song Gang Xu Wuhan National High Magnetic Field Center&School of Physics Huazhong University of Science and TechnologyWuhan430074China Department of Physics Princeton UniversityPrincetonNJ08544USA

By means of the first-principles calculations and magnetic topological quantum chemistry,we demonstrate that the low-energy physics in the checkerboard antiferromagnetic(AFM)monolayer FeSe,very close to an AFM topological insulator that hosts robust edge states,can be well captured by a double-degenerate nearly flat band with fragile topology just below the Fermi *** Wilson loop calculations identify that such fragile topology is protected by the S_(4z) symmetry,which gives rise to a 2D second-order topological insulator that supports the bound state with fractional charge e/2 at the sample *** work provides a platform to study the intriguing properties of magnetic fragile topological electronic *** observations of the edge states and bound states in checkerboard AFM monolayer FeSe can also be well understood in our work.

关键词： topological monolayer topology

Air interface design for edge intelligence

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The Journal of China universities of Posts and Telecommunications 2022年第1期29卷 13-26,124页

作者： Zhang Zezhong Chen Mingzhe Xu Jie Cui Shuguang Future Network of Intelligence Institute(FNii) The Chinese University of Hong Kong(Shenzhen)Shenzhen 518172China Department of Electrical Engineering Princeton UniversityPrincetonNJ 08544USA

Recent breakthroughs in artificial intelligence(AI) give rise to a plethora of intelligent applications and services based on machine learning algorithms such as deep neural networks(DNNs). With the proliferation of Internet of things(IoT) and mobile edge computing, these applications are being pushed to the network edge, thus enabling a new paradigm termed as edge intelligence. This provokes the demand for decentralized implementation of learning algorithms over edge networks to distill the intelligence from distributed data, and also calls for new communication-efficient designs in air interfaces to improve the privacy by avoiding raw data exchange. This paper provides a comprehensive overview on edge intelligence, by particularly focusing on two paradigms named edge learning and edge inference, as well as the corresponding communication-efficient solutions for their implementations in wireless systems. Several insightful theoretical results and design guidelines are also provided.

关键词： artificial intelligence air interface edge intelligence edge inference federated learning

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Integrated Intelligent Electromagnetic Radiator Design for Future THz Communication:A Review

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Chinese Journal of Electronics 2022年第3期31卷 499-515页

作者： LU Xuyang Venkatesh Suresh Saeidi Hooman Sengupta Kaushik UM-SJTU Joint Institute Shanghai Jiao Tong University Electrical and Computer Engineering Princeton University

Advances in 6 G communication changes how machines and humans interact. The blossom of new applications demands significantly higher data bandwidth while preserving the mobility and sustainability of electronic wireless communication systems. It also demands an integrable system that allows convenient interactions between communication units and signal processing units.A review of CMOS-based THz communication system solutions is presented, with a focus on novel systematic EM-circuit co-design philosophy. This review starts with a review of THz power generation, followed by the discussion of THz localization and THz beamforming for efficient high-throughput communication.

关键词： Terahertz Integrated circuits CMOS 6G MIMO

Imaging through scattering media via spatial-temporal encoded pattern illumination

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Photonics Research 2022年第7期10卷 1689-1694页

作者： XINGCHEN ZHAO XIAOYU NIE ZHENHUAN YI TAO PENG MARLAN O.SCULLY Institute for Quantum Science and Engineering Texas A&M UniversityCollege StationTexas 77843USA School of Physics Xi’an Jiaotong UniversityXi’an 710049China Baylor university WacoTexas 76706USA princeton university PrincetonNew Jersey 08544USA

Optical imaging through scattering media has long been a *** approaches have been developed for focusing light or imaging objects through scattering media,but usually,they are either invasive,limited to stationary or slow-moving media,or require high-resolution cameras and complex algorithms to retrieve the *** utilizing spatial-temporal encoded patterns(STEPs),we introduce a technique for the computation of imaging that overcomes these *** a single-pixel photodetector,we demonstrate non-invasive imaging through scattering *** technique is insensitive to the motion of the ***,we demonstrate that our image reconstruction algorithm is much more efficient than correlation-based algorithms for single-pixel imaging,which may allow fast imaging for applications with limited computing resources.

关键词： media scattering illumination

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