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current developments in Lens design and optical engineering XXI 2020

ISBN: (纸本)9781510637702

The proceedings contain 14 papers. The topics discussed include: ultrashort throw lenses with catadioptric relay suitable for flat and curved screens;light field displays for near eye vR and AR;wide angle lens with improved relative illumination characteristics;optimization of a mobile phone camera for as-built performance;inverse designed flat optics with multilevel diffractive lenses;optical design of triple-mode seeker;comparison of passive athermalization results of LWIR optical designs utilizing different infrared optical materials;and design of an anastigmatic three-mirror telescope using freeform surfaces.

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design and Analysis of optical Wireless Communication Systems 4

Design and Analysis of Optical Wireless Communication System...

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4th International Conference on Smart Electronics and Communication, ICOSEC 2023

作者： Kannan, K. Jagadesan, A. Karthika, G. Pokhariya, Hemant Singh Kaliappan, S. Kanimozhi, K.v. R.M.K. College of Engineering and Technology Department of Electronics and Communication Engineering Tamil Nadu Chennai601206 India R.M.K Engineering College Department of Physics Tamil Nadu Kavaraipettai601206 India R.M.D. Engineering College Department of Electronics and Communication Engineering Tamil Nadu Kavaraipettai601206 India Graphic Era Deemed to Be University Department of Computer Science and Engineering Uttarakhand Dehradun248002 India Lovely Professional University Division of Research and Development Punjab Phagwara144411 India Saveetha School of Engineering Saveetha Institute of Medical and Technical Sciences Department of Computer Science and Engineering Tamil Nadu Chennai602105 India

ISBN: (纸本)9798350300888

The design and implementation of Underwater Wireless optical Communication (UWOC) provide important scientific problems. UWOC has the ability to transmit data at a high pace across long distances. This essay makes an effort to concentrate on the complexity of real-world applications and unresolved problems in UWOC systems. The key developments and advancements in the subject, modelling methods, and connection design difficulties are outlined. The goal of this study is to provide recommendations for a practical and trustworthy UWOC design with enhanced performance. Finally, a summary of the key aspects is provided to aid in future UWOC study. © 2023 IEEE.

关键词： Light emitting diodes

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vLC positioning in low data rate for v2v communication 2024

VLC positioning in low data rate for V2V communication

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12th Euro-American Conference on Telematics and Information Systems, EATIS 2024

作者： Giraldo, Luis Miguel Soler, Joaquin Perez Botella-Mascarell, Carmen Juan, vicent Girbes varea, Sandra Roger Torres, Julio Martos Olcina, Raimundo Garcia Electronical Engineering Department Universitat de València Burjassot Valencia46100 Spain Computer Science Department Informatics Department Universitat de València Burjassot Valencia46100 Spain

ISBN: (纸本)9798400717338

The creation and implementation of a system that bridges visible light communication (vLC) with selected identifiers, envisioned as informational beacons, are outlined. This system is adept at controlling LED panels and orchestrating communication between LED lights and the receiving unit, laying the groundwork for vehicle-to-vehicle (v2v) communication systems tailored for precise positioning. The design and assessment of test-bed requirements cater to the anticipation of future v2v optical wireless communication scenarios. Through analysis, it is demonstrated that commercial outdoor lighting can be effectively utilized for v2v positioning, capable of operating under daylight with a data transmission rate of 100 Kbps. Crucially, the system's ability to accurately detect positioning beacons facilitates the localization of vehicles within designated areas of interest, paving the way for the advancement of v2v communication technologies. This comprehensive approach not only validates the feasibility of using vLC for vehicle positioning but also sets a precedent for future developments in v2v communication systems. © 2024 Owner/Author.

关键词： optical communication

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Wideband Dual-Polarized Metasurface Antenna with Polarization Reconfigurable Controlled by Diode and Resistor, Featuring Low RCS

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IEEE Antennas and Wireless Propagation Letters 2025年第5期24卷 1208-1212页

作者： Ding, Zhendong Li, Jiawang Cao, Jianyin Wang, Hao Chia, Michael Yan-Wah Nasimuddin, Nasimuddin Nanjing University of Science and Technology School of Electronic and Optical Engineering Nanjing210094 China Södergatan Eslöv24130 Sweden Institute for Infocomm Research A∗STAR Singapore138632 Singapore

A polarization reconfigurable metasurface wideband antenna with dual polarized and a low radar cross section (RCS) is presented. The antenna employs a diode positioned between two transmission lines to control the current direction and a resistor on a defected-ground branch to manage phase shifts, enabling seamless transitions between circular polarization (CP) and linear polarization (LP). The elliptical metasurface design contributes to a reduced RCS. The design results are verified through measurement, showing an impedance bandwidth (IBW) of 49.1%, an axial ratio bandwidth (ARBW) of 23.2% for the diode is OFF, an IBW of 36.4% for the diode is ON, the IBW of the connected resistor is 40.7%, and the peak gains for the three states are 6.4 dBi, 4.4 dBi, and 4.2 dBi, respectively. The metasurface achieves a low RCS bandwidth ranging from 2 GHz to 24 GHz, showing a 6 dBsm reduction in RCS from 4.9 GHz to 19.7 GHz, which corresponds to a 120.3% decrease compared to a PEC plate. © 2002-2011 IEEE.

关键词： Radar cross section

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Advances in Nanofiber Cathodes for Aluminum-Ion Batteries

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ADvANCED FIBER MATERIALS 2025年第2期7卷 414-442页

作者： Ramasubramanian, Brindha Tipparaju, Sai Krishna vincent, S. Koperski, Maciej Chellappan, vijila Ramakrishna, Seeram Natl Univ Singapore Coll Design & Engn Dept Mech Engn Singapore 117574 Singapore BITS Pilani Dubai Campus Dept Mech Engn Dubai 345055 U Arab Emirates Natl Univ Singapore Inst Funct Intelligent Mat Singapore 117544 Singapore Natl Univ Singapore Coll Design & Engn Dept Mat Sci & Engn Singapore 117575 Singapore

Rechargeable aluminum-ion batteries (AIBs) possess a higher theoretical volumetric capacity than lithium-ion batteries (LIBs) and offer a sustainable, low-cost alternative. However, the performance of AIBs fails to meet commercial standards due to the challenges experienced including volume changes caused by interfacial issues, side reactions of the electrolyte with electrode, and low cyclic stability. These issues are attributed to the inability of existing cathode materials to perform effectively. To address these challenges, 1-dimensional (1D) structures, especially nanofiber (NF) cathodes offer a promising solution due to their higher aspect ratios, specific surface area, flexibility, and quantum scale effects. To date, there has been no comparative analysis of the electrochemical and structural performances of NF based cathodes in AIBs. Thus, this review focuses on the recent developments in various transition metal oxides and chalcogenides of (Mo, v, Mn, Ni, Cu, W, Se, and Co) along with carbon-based NFs as cathodes for AIBs. Challenges were observed in adopting trivalent Al3+ cations as charge carriers and maintaining the structural integrity of the cathode. Several novel approaches have been developed to enhance electrical conductivity, including the incorporation of the metal oxides/chalcogenides with the carbon NF substrates, crystallizing the nanoparticles at high temperatures, and using self-assembly and templating techniques to create multi-dimensional NF films. Other battery components such as separators were replaced with carbonaceous structures in the MnSe based cathodes to increase ion mobility, and Mo current collectors to prevent dendrites. This review includes prospects aimed at improving performance and functionality, based on observations from the discussed work and innovations in AIBs such as compositing, surface functionalization, and defect engineering through ion doping.

关键词： Carbon-based nanofibers Cathodes volume expansion Doping Substrate reinforcement

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Algorithm for compensation of background light in a photo-receptive device for FSO 16

Algorithm for compensation of background light in a photo-re...

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16th International Conference on Correlation Optics, COR 2023

作者： Lipka, v.M. Dobrovolsky, Yu. G. Sorokanyi, Yu. Joint-stock Company Central Design Bureau Rytm Russia Chernivtsi National University Named after Yu. Fedkovich Russia

ISBN: (纸本)9781510671829

In the proposed study, a topical issue of modern electronics is considered - the creation of an algorithm for ensuring the stability of FSO technology against optical interference, and its solution is proposed using a photo-receiving device by optimizing the optical unit (photodiode - light filter) and creating an original design of a photo signal processing circuit that ensures the selection of a useful signal of a certain frequency modulation and compensation of background lighting. The created pair of optical filter - photodiode provides pulsed current monochromatic sensitivity of the photodiode at the level of 0.26 A/W at a wavelength of 980 nm and practically zero sensitivity at wavelengths shorter than 920 nm. The PRD design selects the useful signal in the frequency range of 3 kHz - 2 MHz and suppresses the frequencies of the background signal in the low frequency range from the constant component to 3 kHz. It compensates the background current up to 15 mA, which is equivalent to the power of light interference up to 15 mW. Further research should answer the questions regarding the reliability of the proposed PRD design and the optimization of its optical system. Practical application of PRD is carried out in construction, as well as in geodesy and control of atmospheric purity © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

关键词： Photodiodes

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Analyzing the key architectural and structural factors in the formation of tall timber projects in Europe

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COGENT engineering 2024年第1期11卷

作者： Ilgin, Huseyin Emre Aslantamer, Ozlem Nur Tampere Univ Fac Built Environm Sch Architecture Tampere Finland Bilkent Univ Fac Art Design & Architecture Dept Interior Architecture & Environm Design Ankara Turkiye

As tall wooden structures emerge as a burgeoning and promising sector, offering considerable ecological and financial benefits across their life cycles, their prevalence is on the rise, particularly in Europe. However, the current corpus of literature fails to offer a detailed assessment of the fundamental architectural and structural planning parameters for European tall timber towers (>= 9 stories). To span this gap and improve the comprehension of the developing European tendencies, this study meticulously examined information from 33 tall timber towers in Europe. The principal findings uncovered the following: (i) tall timber buildings predominantly favored residential applications as their primary function, (ii) the prevailing preference for the central core arrangement was evident, (iii) the most prevalent design preference for tall timber buildings was prismatic forms, (iv) widespread adoption of composite materials was evident, with combinations of timber and concrete being particularly prominent, and (v) the structural systems were primarily characterized by shear-frame configurations. By revealing these present-day attributes of tall wooden towers in Europe, this article is anticipated to offer valuable insights to architectural designers, assisting and directing them in the formulation and implementation of forthcoming developments in this domain.

关键词： Timber/wood tall timber projects Europe architectural design factors structural design factors Dr Montemurro Marco, Arts et M & eacute tiers Sciences et Technologies, France design Architecture Building and Construction

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Ortho- to para-Hydrogen Conversion Kinetics: New Experimental Data and an Industrial Perspective

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INDUSTRIAL & engineering CHEMISTRY RESEARCH 2024年第46期63卷 20065-20078页

作者： Wijnans, Sanne Zietara, Rafal Pearson, Emily Boele, Michiel Reynolds, Michael A. Energy Transit Campus Amsterdam ETCA Shell Global Solut Int BV NL-1031HW Amsterdam Netherlands Quantum Technol Corp Squamish BC V8B 0V2 Canada Shell Technol Ctr Houston STCH Shell Catalysts & Technol Houston TX 77082 USA

Hydrogen is a remarkable molecule with applications ranging from refining and petrochemicals to medicine, to space travel and the energy transition. It consists of two spin isomers, namely orthohydrogen (ortho-H-2) and parahydrogen (para-H-2), that are separated in energy by only 1.455 kJ/mol. Chemically, these isomers are indistinguishable, yet each isomer has its own unique physical properties including thermal conductivity, optical behavior, and specific heat capacity. These physical traits are important during hydrogen liquefaction because the para-H-2 form is more stable at cryogenic temperatures (i.e., T < 77 K). In the context of energy transition, the production and supply of liquid hydrogen requires the application of a catalyst in liquefaction plants to induce hydrogen isomer interconversion via the process known colloquially as "spin-flipping." The same catalyst can also improve brightness in neutron spallation sources, or enable the parahydrogen induced hyperpolarization (PHIP) technique used in magnetic imaging. Although the current preferred catalyst for these applications is a class of iron oxide materials, only a limited set of catalyst performance data is available. A confluence of this data was measured more than half a century ago, often using catalyst samples synthesized at lab-scale, and/or derived under reaction conditions irrelevant for practical application. Consequently, the few widely cited kinetic models for this system were developed by fitting data against an even smaller subset of this data limited by temperature or pressure conditions, all from the 1950s/1960s. It is reasonable to question if these models have predictive capabilities that are relevant for the current-day design using today's commercial catalyst. Our work compares three of these kinetic models against new Ionex Type O-P Catalyst conversion data, spanning >300 data points across a broad and industrially relevant temperature-pressure window, and four published experimenta

关键词： Specific heat of solids

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A low quiescent current high PSRR LDO circuit 3

A low quiescent current high PSRR LDO circuit

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3rd International Conference on Computer Technology, Information engineering, and Electron Materials, CTIEEM 2023

作者： Zhou, Haining Zhu, Bin Lin, Haijun Lei, Yajie School of Opto-Electronic and Communication Engineering Xiamen University of Technology Fujian Xiamen China

ISBN: (纸本)9781510672925

In order to meet the needs of Internet of Things devices and wearable electronic devices for lower standby power consumption and power supply noise, a Low Dropout Regulator (LDO) circuit with low quiescent current and high power supply rejection ratio is designed. The core circuit is bandgap and error amplifier. This design is based on the 0.18um BCD process. The Spectre simulation of Cadence has been used to test and simulate the circuit. The simulation result indicates that the bandgap voltage is 1.209v, the temperature coefficient is 19.76ppm/°C in the range of -25∼125°C, and the power supply rejection ratio is 69dB at low frequency. The circuit can deliver a quiescent current of around 776nA and exhibits good temperature characteristics and low quiescent current. © 2024 SPIE.

关键词： Energy gap

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Application-Based Optimization of Oxide-Confined vCSEL 14

Application-Based Optimization of Oxide-Confined VCSEL

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Semiconductor Lasers and Applications XIv 2024

作者： Nashed, A.I. Lestrade, Michel Li, Z.Q. Li, Z.M. Simon Crosslight Software Inc. 230-3410 Lougheed Hwy VancouverBCV5M 2A4 Canada

ISBN: (数字)9781510681958

ISBN: (纸本)9781510681941

In this work, we present the simulation and analysis of an oxide-confined vertical-cavity surface-emitting laser (vCSEL) using the Finite Difference Frequency Domain (FDFD) microcavity model, integrated within the Crosslight’s PICS3D simulation package. By utilizing a full vectorial microcavity approach, both fundamental and higher-order optical modes are accurately captured, offering detailed insights into the effects of key structural parameters of the optical cavity. This study focuses on the impact of the oxide layer’s position and thickness on mode behavior, lasing mode selection, and threshold current in large-aperture vCSELs. The optimized vCSEL design achieves a threshold current of 0.7 mA and a far-field divergence angle of approximately 8°. © 2024 SPIE.

关键词： Microcavities

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