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Advances in selective laser sintering of polymers

International Journal of Extreme Manufacturing 2022年第4期4卷 20-56页

作者： Wei Han Lingbao Kong Min Xu Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing Department of Optical Science and EngineeringFudan UniversityShanghai 200433People’s Republic of China

Polymers are widely used materials in aerospace,automotive,construction,medical devices and *** are being promoted rapidly due to their ease of manufacturing and improved material *** on polymer processing technology should be paid more attention to due to the increasing demand for polymer *** laser sintering(SLS)uses a laser to sinter powdered materials(typical polyamide),and it is one of the critical additive manufacturing(AM)techniques of *** irradiates the laser beam on the defined areas by a computer-aided design three-dimensional(3D)model to bind the material together to create a designed 3D solid *** has many advantages,such as no support structures and excellent mechanical properties resembling injection moulded parts compared with other AM ***,the ability of SLS to process polymers is still affected by some defects,such as the porous structure and limited available types of SLS ***,this article reviews the current state-of-the-art SLS of polymers,including the fundamental principles in this technique,the SLS developments of typical polymers,and the essential process parameters in ***,the applications of SLS are focused,and the conclusions and perspectives are discussed.

关键词： selective laser sintering additive manufacturing laser powder bed fusion 3D printing polymer

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Optimal Real-Weighted Beamforming with Application to Linear and Spherical Arrays

arXiv

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arXiv 2024年

作者： Tourbabin, v. Agmon, M. Rafaely, B. Tabrikian, J. Department of Electrical and Computer Engineering Ben-Gurion University of the Negev Be’er-Sheva84105 Israel

One of the uses of sensor arrays is for spatial filtering or beamforming. current digital signal processing methods facilitate complex-weighted beamforming, providing flexibility in array design. Previous studies proposed the use of real-valued beamforming weights, which although reduce flexibility in design, may provide a range of benefits, e.g. simplified beamformer implementation or efficient beamforming algorithms. This paper presents a new method for the design of arrays with real-valued weights, that achieve maximum directivity, providing closed-form solution to array weights. The method is studied for linear and spherical arrays, where it is shown that rigid spherical arrays are particularly suitable for real-weight designs as they do not suffer from grating lobes, a dominant feature in linear arrays with real weights. A simulation study is presented for linear and spherical arrays, along with an experimental investigation, validating the theoretical developments. © 2024, CC BY.

关键词： Beamforming

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Analytic formulation of a spherochromatic collimator lens 11

Analytic formulation of a spherochromatic collimator lens

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Conference on current developments in Lens design and optical engineering XXI

作者： Gonzalez-Acuna, Rafael G. Gutierrez-vega, Julio C. Tecnol Monterrey Photon & Math Opt Grp Monterrey Mexico

We introduce a closed-form formula to design a spherochromatic collimator singlet lens. The light for three different wavelengths is collimated at the output of the lens. We test the singlet lens using ray-tracing met... 详细信息

ISBN: (数字)9781510637719

ISBN: (纸本)9781510637719

关键词： optical design aspheric collimator

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A BIM-Based Approach of Electrical Network Analysis and Applications Using GIS Tools 1

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2nd International Conference on Sustainable Construction Technologies and Advancements in Civil engineering, ScTACE 2021

作者： Tejaswini, v. Kesava Rao, P. Dhanamjaya Rao, E.N. Nagaraja, R. Sinha, S.K. Rajan, K.S. Hyderabad India National Institute of Rural Development and Panchayat Raj Hyderabad India Department of Geology Andhra University Andhra Pradesh Visakhapatnam India Hyderabad India Survey of India Uppal Hyderabad India Hyderabad Gachibowli India

ISBN: (数字)9789811901898

ISBN: (纸本)9789811901881

Building Information Modeling is a sophisticated technology possessing intellectual tools that help planners and architects to design sustainable buildings and carryout performance analysis based on various aspects. Apart from the existing building elements, a network connecting each building component is of vital importance in order to generate organized plans. Building Information Modeling when embedded with Geographic Information System delivers versatile applications in the world of both Geo Spatial field of studies as well as Architecture, engineering and Construction Industry. The current research is one such attempt to understand the power of Geographic Information System tools in building models especially in solving complicated network connections. designing the electrical network and planning the circuitry information in such a way so as to avoid faulty or poor connections in between the inter circuit elements is successfully achieved with the help of this integration. Initially, building model is generated to the high level of detail and electrical fixtures are organized with in a power distribution system using Revit Architecture. The virtual network wiring made in Building model is physically connected using three dimensional Polyline features in Geographic Information System platform and the created Network of electrical elements is utilized for Geometric Network Analysis. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Architectural design

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Ultrathin Ti_(3)C_(2) nanowires derived from multi-layered bulks for high-performance hydrogen evolution reaction

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Chinese Chemical Letters 2022年第1期33卷 557-561页

作者： Weiwei Zhao Beibei Jin Longlu Wang Chengbo Ding Mengyue Jiang Tiantian Chen Shuaihang Bi Shujuan Liu Qiang Zhao Key Laboratory for Organic Electronics and Information Displays&Jiangsu Key Laboratory for Biosensors Institute of Advanced Materials(IAM)Nanjing University of Posts&Telecommunications(NUPT)Nanjing 210023China College of Electronic and Optical Engineering&College of Microelectronics Institute of Flexible Electronics(Future Technology)Nanjing University of Posts&Telecommunications(NUPT)Nanjing 210023 China

One-dimensional ultrathin nanowires(NWs)offer a great deal of promising properties for electrochemical energy storage and conversion due to their nanoscale confinement effect and high surface-to-volume *** is highly desirable to precisely design and synthesize ultrathin Ti_(3)C_(2)NWs in the aspect of size,crystalline structure and ***,we report a simple alkalization strategy to design the ultrathin Ti_(3)C_(2)NWs for hydrogen evolution reaction(HER)by modulating the surface-active *** design principle can well improve the amount of the defect sites and ion accessibility to increase the interactions between Ti_(3)C_(2)NWs and H^(*).The optimized Ti_(3)C_(2)NWs achieve an overpotential of 476 mv at the current density of 10 mA/cm^(2)and a Tafel slope of 129 mv/dec for HER catalysis,which are superior to that of Ti_(3)C_(2)nanosheets and m-Ti_(3)C_(2).It paves an avenue for the rational transformation of MXene bulks to one-dimensional NWs catalysts for HER.

关键词： MXene Ti_(3)C_(2)nanowires Ultrathin films Chemical transformation Hydrogen evolution reaction

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A 94 GHz Bandwidth Transimpedance Amplifier in 55nm SiGe BiCMOS for High Speed optical Receivers

A 94 GHz Bandwidth Transimpedance Amplifier in 55nm SiGe BiC...

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Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems

作者： Lachlan Cuskelly Christopher Falt Peter Schvan Electrical and Computer Engineering University of California Los Angeles Los Angeles California ASIC Design Ciena Corporation Ottawa Canada

A transimpedance amplifier with a bandwidth of 94 GHz is presented and on chip measurements are discussed. The measured gain of the amplifier at low frequencies is 55 $\mathrm{dB}\Omega$, peaking to 61 $\mathrm{dB}\Omega$ at 78 GHz. The circuit was designed in a cutting edge 55nm SiGe BiCMOS technology, occupies a pad limited area of 0.02 mm 2 , and consumes 14 m A of current from a 3.3v supply. The circuit achieves an average input referred current noise of 11 pA/$\sqrt{Hz}$, making it suitable for future high speed optical receivers.

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Strain engineering for Pseudo-Magnetic Fields in Graphene 5

Strain Engineering for Pseudo-Magnetic Fields in Graphene

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Conference on 2D Photonic Materials and Devices v Part of SPIE Photonics West OPTO Conference

作者： Luo, Manlin Sun, Hao Qi, Zhipeng Lu, Kunze Chen, Melvina Kang, Dong-Ho Kim, Youngmin Burt, Daniel Yu, Xuechao Wang, Chongwu Kim, Young Duck Duck, Young Wang, Qi-Jie Nam, Donguk Nanyang Technol Univ Sch Elect & Elect Engn 50 Nanyang Ave Singapore 639798 Singapore Nanyang Technol Univ Sch Phys & Math Sci 21 Nanyang Link Singapore 637371 Singapore Nanjing Univ Informat Sci & Technol Sch Phys & Optoelect Engn Nanjing 210044 Peoples R China Gwangju Inst Sci & Technol Sch Elect Engn & Comp Sci Gwangju 61005 South Korea Kyung Hee Univ Dept Phys Seoul 02477 South Korea

ISBN: (纸本)9781510648784;9781510648777

The potential for establishing energy gaps by pseudo-magnetic fields in strain-engineered graphene has sparked much interest recently. However, the limited sizes of induced pseudo-magnetic fields and the complicated platforms for straining graphene have thus far prevented researchers from harnessing the unique pseudo-magnetic fields in optoelectronic devices. In this work, we present an experimental demonstration of triaxially strained suspended graphene structures capable of obtaining quasi-uniform pseudo-magnetic fields over a large scale. The novel metal electrode design functions as both stressors and current injectors. We also propose a hybrid laser structure employing a 2D photonic crystal and triaxially strained graphene as an optical cavity and gain medium, respectively.

关键词： Strain engineering graphene pseudo-magnetic fields laser structure optoelectronic devices

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Optimization modeling of a Cs-sputter ion source for AMS of 10Be

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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 2024年 549卷

作者： Zhao, Xiaolei Beijing Normal Univ Interdisciplinary Res Ctr Earth Sci Frontier BNU AMS Lab Beijing 100875 Peoples R China Beijing Normal Univ State Key Lab Earth Surface Proc & Resource Ecol Beijing 100875 Peoples R China

When measuring Be-10 at the sub-10(-13 10)Be/Be-9 ratio with accelerator mass spectrometry (AMS), it is highly desirable to produce maximum (BeO-)-Be-9 currents >20 mu A and extract those without losses due to the geometry of the ion source. Unfortunately, this is often not the case, and experiences in measuring the same samples using different ion sources have been quite variable. Using the SO110-B and -C ion sources manufactured by High voltage engineering (HvE), the maximum (BeO-)-Be-9 beam current extracted is typically 2-4 mu A and 8-12 mu A, respectively, whereas 20-25 mu A has been experienced elsewhere. The significantly smaller maximum beam currents suggest that the optical design of the SO110-B/C sources still requires optimization. Using the modeling program PBGUNS v5.2, this work reports a detailed examination of the SO110-B/C extraction performance in response to the sample surface cratering. It is found that the electric field on the sample surface is too strong so that part of the negative ion beam is being blocked by the ionizer as soon as a crater starts to develop in the sample. Fortunately, remarkably simple remedy solutions are found. With only minor adjustment to the shapes and positions of the relevant electrodes, the renewed maximum (BeO-)-Be-9 beam current is predicted to reach 25-30 mu A and to remain fully extracted throughout the course of sample surface cratering.

关键词： 860 type Cs-sputter ion sources Ion optical modeling (9)BeO(-)beam current

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design of drive circuit for turbine electromechanical hydraulic servo valve control 3

Design of drive circuit for turbine electromechanical hydrau...

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3rd International Conference on Electronics, Electrical and Information engineering, ICEEIE 2023

作者： Zhu, Haotian Ni, Xiaoming Du, Baiwan Yu, Zhaoxian College of Science Beijing Information Science and Technology University Beijing China Beijing SP Zhishen Control Technology Co. Ltd. Beijing China

ISBN: (纸本)9781510671423

For steam power control of steam turbine, electro-hydraulic servo valve is a necessary component. However, the electro-hydraulic servo valve of steam turbine has a high requirement for the driving ability of the drive circuit, and the ordinary drive circuit cannot meet its requirements. Therefore, this paper designs a driving circuit with greater driving capacity for electro-hydraulic servo valve. The problem of insufficient carrying capacity of OP07 is solved by combining OP07 operational amplifier and push-pull circuit to improve its driving capacity. Taking 0-2.5v input voltage as an example, the optimized driving circuit is designed and simulated. The simulation results show that in the voltage mode, the drive circuit can drive the load with smaller resistance value and output larger current than the common electro-hydraulic servo valve drive circuit, which further improves the drive ability of the electro-hydraulic servo valve drive circuit. © 2023 SPIE.

关键词： Timing circuits

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Rationally heteroarylated pyridines as hole transport materials for OLEDs

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Physical Chemistry Chemical Physics 2023年第29期25卷 19648-19659页

作者： Kumar, Krishan Karmakar, Anirban Chen, Feng-Rong Jou, Jwo-Huei Ghosh, Subrata Banik, Subrata Kumar, Sunil School of Chemical Sciences IIT Mandi Himachal Pradesh 175005 India Centro de Química Estrutural Instituto Superior Técnico Avenida Rovisco Pais Lisboa1049-001 Portugal Department of Materials Science and Engineering National Tsing Hua University 101 Sec. 2 Guang-Fu Road Hsinchu30013 Taiwan Department of Chemistry School of Chemical and Biotechnology SASTRA Deemed University Tamil Nadu Thanjavur613401 India

The advancement in developing highly efficient hole transport materials for OLED devices has been a challenge over the past several years. For an efficient OLED device, there should be an efficient promotion of charge carriers from each electrode and effective confinement of triplet excitons in the emissive layer of the phosphorescent OLED (PhOLED). Thus, the development of stable and high triplet energy hole transport materials is in urgent demand for high-performing PhOLED devices. The present work demonstrates the development of two hetero-arylated pyridines as high triplet energy (2.74-2.92 ev) multifunctional hole transport materials to reduce the exciton quenching and to enhance the extent of charge carrier recombination in the emissive layer. In this regard, we report the design, synthesis, and theoretical modeling with electro-optical properties of two molecules, namely PrPzPy and MePzCzPy, with suitable HOMO/LUMO energy levels and high triplet energy, by incorporating phenothiazine as well as other donating units into a pyridine scaffold, and finally developing a hybrid phenothiazine-carbazole-pyridine based molecular architecture. The natural transition orbital (NTO) calculations were done to analyze the excited state sensation in these molecules. The long-range charge transfer characteristics between the higher singlet and triplet states were also analyzed. The reorganization energy of each molecule was calculated to examine their hole transportability. The theoretical calculations for PrPzPy and MePzCzPy revealed that these two molecular systems could be promising materials for the hole transport layer of OLED devices. As a proof of concept, a solution-processed hole-only device (HOD) of PrPzPy was fabricated. The increase in current density with an increase in operating voltage in the range of ∼3-10 v supported that the suitable HOMO energy of PrPzPy can facilitate the hole transportation from the hole injection layer (HIL) to the emissive layer (EML).

关键词： Pyridine

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