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In Situ Mineralization of Biomass-Derived Hydrogels Boosts Capacitive Electrochemical Energy Storage in Free-Standing 3D Carbon Aerogels

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Energy & Environmental Materials 2024年第2期7卷 359-371页

作者： Anjali Achazhiyath Edathil Babak Rezaei Kristoffer Almdal Stephan Sylνest Keller National Centre for Nano Fabrication and Characterization DTU NanolabTechnical University of Denmark2800LyngbyDenmark dtu Chemistry Technical University of Denmark2800LyngbyDenmark

Here,a novel fabrication method for making free-standing 3D hierarchical porous carbon aerogels from molecularly engineered biomass-derived hydrogels is *** situ formed flower-like CaCO_(3)molecularly embedded within the hydrogel network regulated the pore structure during in situ mineralization assisted one-step activation graphitization(iMAG),while the intrinsic structural integrity of the carbon aerogels was *** homogenously distributed minerals simultaneously acted as a hard template,activating agent,and graphitization *** decomposition of the homogenously distributed CaCO_(3)during iMAG followed by the etching of residual CaO through a mild acid washing endowed a robust carbon aerogel with high porosity and excellent electrochemical *** 0.5 mA cm^(-2),the gravimetric capacitance increased from 0.01 F g^(-1)without mineralization to 322 F g^(-1)with iMAG,which exceeds values reported for any other free-standing or powder-based biomass-derived carbon *** outstanding cycling stability of~104%after 1000 cycles in 1 M HClO4 was *** assembled symmetric supercapacitor device delivered a high specific capacitance of 376 F g^(-1)and a high energy density of 26 W h kg^(-1)at a power density of 4000 W kg^(-1),with excellent cycling performance(98.5%retention after 2000 cycles).In combination with the proposed 3D printed mold-assisted solution casting(3DMASC),iMAG allows for the generation of free-standing carbon aerogel architectures with arbitrary ***,the novel method introduces flexibility in constructing free-standing carbon aerogels from any ionically cross-linkable biopolymer while maintaining the ability to tailor the design,dimensions,and pore size distribution for specific energy storage applications.

关键词： biomass carbon aerogel sustainable energy materials free-standing supercapacitors

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Numerical design of an efficient Ho^(3+)-doped InF3 fiber laser at~3.2μm

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Journal of Electronic Science and Technology 2024年第3期22卷 35-46页

作者： Shi-Yuan Zhou Hong-Yu Luo Ya-Zhou Wang Yong Liu State Key Laboratory of Electronic Thin Films and Integrated Devices School of Optoelectronic Science and EngineeringUniversity of Electronic Science and Technology of ChinaChengdu611731China dtu Electro Technical University of DenmarkKongens Lyngby2800Denmark

In this work,we theoretically unlock the potential of Ho^(3+)-doped InF3 fiber for efficient~3.2μm laser generation(from the 5F4,5S2→5F5 transition),by employing a novel dual-wavelength pumping scheme at 1150 nm and 980 nm,for the first *** clad-coupled 1150 nm pumping of 5 W,~3.2μm power of 3.6 W has been predicted with the optical-to-optical efficiency of 14.4%.Further efficient power scaling,however,is blocked by the output saturation with 980 nm *** alleviate this behavior,the cascaded 5I5→5I6 transition,targeting~3.9μm,has been activated simultaneously,therefore accelerating the population circulation between the laser upper level 5F4,5S2 and long-lived 5I6 level under 980 nm *** a result,enhanced~3.2μm power of 4.68 W has been obtained with optical-to-optical efficiency of 15.6%.Meanwhile the~3.9μm laser,yielding power of 2.76 W with optical-to-optical efficiency of 9.2%,is theoretically achievable as well with a moderate heat load,of which the performance is even better than the prior experimentally and theoretically reported Ho^(3+)-doped InF3 fiber lasers emitting at~3.9μm *** work demonstrates a versatile platform for laser generation at~3.2μm and~3.9μm,thus providing the new opportunities for many potential applications,e.g.,polymer processing,infrared countermeasures,and free-space communications.

关键词： Cascaded Fiber laser Holmium Mid-infrared

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Optimal Planning of Hybrid AC/DC Low-voltage Distribution Networks Considering DC Conversion of Three-phase Four-wire Low-voltage AC Systems

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 141-153页

作者： Bo Zhang Lu Zhang Wei Tang Gen Li Chen Wang the College of Information and Electrical Engineering China Agricultural UniversityBeijing 100083China the Electric Energy Group Department of Engineering TechnologyTechnical University of Denmark(DTU)2750 BallerupDenmark the Power Distribution Technology Center State Grid Beijing Electric Power Research InstituteBeijing 100075China

The increasing integration of distributed household photovoltaics(PVs)and electric vehicles(EVs)may further ag gravate voltage violations and unbalance of low-voltage distribu tion networks(LVDNs).DC distribution networks can increase the accommodation of PVs and EVs and mitigate mutilple pow er quality problems by the flexible power regulation capability of voltage source *** paper proposes schemes to es tablish hybrid AC/DC LVDNs considering the conversion of the existing three-phase four-wire low-voltage AC systems to DC op *** characteristics and DC conversion constraints of typical LVDNs are *** addition,converter configura tions for typical LVDNs are proposed based on the three-phase four-wire characteristics and quantitative analysis of various DC ***,an optimal planning method of hybrid AC/DC LVDNs is proposed,which is modeled as a bi-level programming model considering the annual investments and three-phase *** are conducted to verify the effectiveness of the proposed optimal planning *** ulation results show that the proposed optimal planning method can increase the integration of PVs while simultaneously reduc ing issues related to voltage violation and unbalance.

关键词： Optimal planning low-voltage distribution net work three-phase unbalance DC conversion

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Processing techniques of selected oilseed by-products of potential use in animal feed: Effects on proximate nutrient composition, amino acid profile and antinutrients

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Animal Nutrition 2018年第4期4卷 442-451页

作者： Collins P.Duodu Daniel Adjei-Boateng Regina E.Edziyie Nelson W.Agbo Godfred Owusu-Boateng Bodil K.Larsen Peter V.Skov Department of Fisheries and Watershed Management Faculty of Renewable Natural Resources Kwame Nkrumah University of Science and TechnologyPMB University Post Office Section for aquaculture DTU Aqua Technical University of Denmark

The effects of processing by autoclaving(AC), soaking(SK), short-term fermentation(S-TF, 4 d) and longterm fermentation(L-TF, 14 d) on the nutritional composition, amino acid profile and some antinutrients were determined for cottonseed meal(CSM), groundnut meal(GNM) and groundnut husk(GH) in this study. After processing, crude protein content improved by 11% after L-TF, and crude lipid content 25%after SK for CSM; crude protein content improved by 27% after S-TF and L-TF, and crude lipid content 13%after SK for GNM. Soaking and fermentation were shown to significantly increase essential amino acid contents by 44%(SK, methionine) in CSM and 46% in GNM(L-TF, histidine). Phosphorus content was reduced by 59% in CSM and 57% in GNM by L-TF. All processing techniques, with the exception of AC,reduced phytic acid and gossypol contents in CSM and GNM. It was concluded that SK and fermentation were simple, cost-effective, and efficient ways to improve the nutritional value of the selected oilseed byproducts.

关键词： Amino acid Autoclaving Fermentation Proximate composition Soaking

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High-speed ultra-wideband wireless signals over fiber systems:photonic generation and DSP detection

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The Journal of China Universities of Posts and Telecommunications 2009年第4期16卷 7-11页

作者： Timothy Braidwood Gibbon Idelfonso Tafur Monroy dtu Fotonik-Department of Photonics Engineering Technical University of Denmark

We firstly review the efforts in the literature on ultra-wideband （UWB）-over-fiber systems. Secondly, we present experimental results on photonic generation of high-speed UWB signals by both direct modulation and external optical injecting an uncooled semiconductor laser. Furthermore, we introduce the use of digital signal processing （DSP） technology to receive the generated UWB signal at 781.25 Mbit/s. Error-free transmission is achieved.

关键词： UWB-over-fiber photonic generation DSP

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Observation of Blobs and Holes in the Boundary Plasma of EAST Tokamak

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Plasma Science and Technology 2011年第4期13卷 410-414页

作者：颜宁徐国盛张炜常加峰王亮刘少承刘鹏汪惠乾蒋敏熊豪丁斯晔万宝年高翔 V.NAULIN A.H.NIELSEN J.JuulRASMUSSEN Institute of Plasma Physics Chinese Academy of Sciences Association Euratom-Risφ dtu

Intermittent convective transport at the edge and in the scrape-off layer （SOL） of EAST was investigated by using fast reciprocating Langmuir probe. Holes, as part of plasma structures, were detected for the first time inside the shear layer. The amplitude probability distribution function of the turbulence is strongly skewed, with positive skewed events （＂blobs＂） prevailing in the SOL region and negative skewed events （＂holes＂） dominant inside the shear layer. The statistical properties coincide with previous observations from JET. The generation mechanism of blobs and holes is also discussed. In addition burst structure and dynamics character of them are also presented.

关键词： intermittent transport blobs holes generation mechanism dynamics character

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Range Extension and Channel Capacity Increase in Impulse-Radio Ultra-Wideband Communications

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Tsinghua Science and Technology 2010年第2期15卷 169-173页

作者： Roberto Rodes Antonio Caballero Jesper Bevensee Jensen Timothy Braidwood Gibbon Neil Guerrero Gonzalez Idelfonso Tafur Monroy dtu Fotonik Department of Photonics Engineering Technical University of Denmark

We theoretically analyze the channel capacity of a 5th-order Gaussian pulse-based ultra-wideband （UWB） system and experimentally demonstrate 2 Gbit/s UWB-over-fiber transmission systems incorporating wireless transmission. Both electrical and photonic UWB pulse generation methods are employed and its performance is compared. By utilizing optimum UWB pulse design and employing a digital signal processing （DSP） receiver, a bit-error-rate above the forward error correction （FEC） limit for 8 meters of wireless＇emis- sion is obtained in our photonic generation UWB system. A noticeable increase in the channel capacity is achieved compared to previously reported results.

关键词： impulse radio ultra-wideband UWB-over-fiber channel capacity personal area networks

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Frequency Stability of Power System with Large Share of Wind Power Under Storm Conditions

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Journal of Modern Power Systems and Clean Energy 2020年第2期8卷 219-228页

作者： Kaushik Das Feng Guo Edgar Nuno Nicolaos A.Cutululis the Department of Wind Energy Technical University of Denmark(DTU)RiseDenmark Suzlon Energy Limited RostockGermany

The operation of transmission systems with large share of wind power is specially challenging under storm *** the stormy wind speed conditions,wind turbine protection system is designed to shut down the turbine to avoid excessive mechanical *** sudden loss of wind power from large offshore plants is difficult to forecast accurately,which results in a large amount of power *** severity of such a wind power imbalance towards frequency stability needs to be studied for the future power *** addition,the overhead transmission lines can also be affected during storms,thereby increasing their probability of failure in the operation of power system under the islanded *** paper investigates how the stormy weather can threaten the frequency stability of future Danish power system with large share of wind power and how to avoid the frequency instability through proper control and defence strategies such as high-voltage direct current(HVDC)control and load *** studies are performed for ramp rates of HVDC control,load shedding strategies,inertia of the system with different volumes of disturbances to understand their impact on frequency stability.

关键词： Emergency control frequency stability storm security wind power

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Product Fingerprints for the Evaluation of Tool/Polymer Replication Quality in Injection Molding at the Micro/Nano Scale

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Nanomanufacturing and Metrology 2021年第4期4卷 278-288页

作者： Dario Loaldi Francesco Regi Dongya Li Nikolaos Giannekas Matteo Calaon Yang Zhang Guido Tosello Department of Mechanical Engineering Technical University of Denmark(DTU)2800 Kongens LyngbyDenmark

Replication processes for the manufacturing of micro/nano-structured components are characterized by a certain degree of precision and *** transcription loss,or replication fidelity,defines the geometrical and dimensional correspondence of micro/nano-structure from metal tool inserts into plastic patterned *** employment of a vast spectrum of micro/nano-structured geometries calls for methodologies that can be used for the estimation of replication *** study presents a number of product fingerprints,which propose multiple ways to characterize micro/nano structures in replication *** fidelity yielded values above 80%and up to 96%depending on the considered product fingerprints and their ***,a correlation of the product fingerprint with the process parameters was found to optimize the replication *** uncertainty accompanies the analysis of the product fingerprints,enabling a standardized,robust,and quantitative methodology for process learning,modeling,and optimization.

关键词： Micro/nano replication Product fingerprinting Metrology Micro injection molding

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Test and performance optimization of nozzle inclination angle and swirl combustor in a low-tar biomass gasifier:a biomass power generation system perspective

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Carbon Resources Conversion 2022年第2期5卷 139-149页

作者： Md Mashiur Rahman Agricultural Engineering Division Regional Agricultural Research StationBangladesh Agricultural Research InstituteJamalpur2000Bangladesh dtu Chemical Engineering Technical University of Denmark(DTU)Frederiksborgvej 399DK 4000 RoskildeDenmark

A nozzle inclination angle and swirl combustor inside the low-tar biomass(LTB)gasifier reactor were tested and optimized to evaluate these effects on tar reduction to design tar-free producer *** tar reduction process is mainly based on the concept of a swirling flow created by the nozzle inclination angle,with the inclination angle of 55◦to the radial line,allowing good mixing between pyrolysis gases and gasifying agents.A separate swirl combustor has created large internal annular and reverses flow zones with the help of swirl flow,resulting in homogenized temperature inside the combustor and providing longer residence time;both have a positive effect on the combustion of mixed gasifying air-pyrolysis gases by the thermal cracking in the partial oxidation *** ratio(RR)and combustion degree of volatiles are the two optimization parameters for evaluating the performance of NIA and swirl *** result observed that outstanding tar reduction occurred in this novel *** 86.5 and 12.8%of tar compounds are broken down in the partial oxidation zone and pyrolysis zone using the novel swirl combustor and NIA,respectively;gas outlet has observed producer gas having tar concentration of less than 1%.The optimization results reveal that a lower recycling ratio(recycle gas/gasifying air)and a higher combustion degree of volatiles perform better in biomass ***,this system generated producer gas with the tar concentration at an extremely low level of 7.4 mg/Nm^(3)for a biomass moisture content of 9%and appeared the lower heating value of 4.6–5.1 MJ/Nm^(3).This lower tar concentration might be directly coupled with an internal combustion engine or a gas turbine for power generation.

关键词： Biomass gasification Downdraft moving bed gasifier Nozzle inclination angle Swirl combustor Swirl flow Tar Reduction

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