检索结果-南通市图书馆

Chinese journal of Aeronautics 2017年第4期30卷 1427-1440页

作者： Young H.YOU Sung N.jUNG chang j.kim Department of Aerospace Information Engineering Konkuk University Seoul 05019 Republic of Korea

The best active twist schedules exploiting various waveform types are sought taking advantage of the global search algorithm for the reduction of hub vibration and/or power required of a rotor in high-speed conditions. The active twist schedules include two non-harmonic inputs formed based on segmented step functions as well as the simple harmonic waveform input. An advanced Particle Swarm assisted Genetic Algorithm（PSGA） is employed for the optimizer. A rotorcraft Computational Structural Dynamics（CSD） code CAMRAD II is used to perform the rotor aeromechanics analysis. A Computation Fluid Dynamics（CFD） code is coupled with CSD for verification and some physical insights. The PSGA optimization results are verified against the parameter sweep study performed using the harmonic actuation. The optimum twist schedules according to the performance and/or vibration reduction strategy are obtained and their optimization gains are compared between the actuation cases. A two-phase non-harmonic actuation schedule demonstrates the best outcome in decreasing the power required while a four-phase non-harmonic schedule results in the best vibration reduction as well as the simultaneous reductions in the power required and vibration. The mechanism of reduction to the performance gains is identified illustrating the section airloads, angle-of-attack distribution, and elastic twist deformation predicted by the present approaches.

关键词： Active twist High-speed flight Hub vibration Non-harmonic Power required

Investigation of operation and degradation mechanisms in ZnTeSe blue quantum-dot light-emitting diodes by identifying recombination zone

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第7期17卷 6527-6533页

作者： Oul Cho Sujin Park Hogeun chang jiwhan kim jaekwon kim Sungwoo kim Taehyung kim jeonghun Kwak Department of Electrical and Computer Engineering Inter-university Semiconductor Research Centerand Soft Foundry InstituteSeoul National UniversitySeoul 08826Republic of Korea Material Research Center Samsung Advanced Institute of TechnologySuwonGyeonggi-do 16419Republic of Korea

ZnTeSe quantum dots(QDs),recognized as promising eco-friendly blue electroluminescent emitters,remain under-explored in light-emitting diode(LED)***,to elucidate the operation and degradation mechanisms of ZnTeSe blue QD-LEDs,stacked ZnTeSe QD layers with discernable luminescence are designed by varying Te doping concentrations,and the recombination zones(RZs)of the blue QD-LEDs are *** RZs are identified near the hole-transport layer(HTL),confirmed by angular-dependent electroluminescence measurements and optical *** addition,in order to investigate carrier dynamics in the process of recombination,the transient electroluminescence(tr-EL)signals of the dichromatic QD-LEDs are *** a result,it is inferred that the RZ initially formed near the electron-transport layer(ETL)due to the high injection barriers of ***,due to the fast electron mobility,the RZ shifts toward the HTL as the operating current *** the device lifetime tests,the RZ remains stationary while the photoluminescence(PL)corresponding to the RZ undergoes a substantial decrease,indicating that the degradation is accelerated by the concentrated *** this study contributes to a deeper understanding of the operational mechanisms of ZnTeSe blue QD-LEDs.

关键词： quantum dots light-emitting diodes degradation recombination zones carrier dynamics

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

自适应正则化滤波化极方法研究

地球物理学报 2024年第3期67卷 1255-1272页

作者：何涛王皓张义蜜王万银 Colin G.Farquharson j.kim Welford 长安大学地质工程与测绘学院西安710054 海洋油气勘探国家工程研究中心北京100028 中国科学院海洋地质与环境重点实验室山东青岛266071 Department of Earth Sciences Memorial University of NewfoundlandSt.John'sAlB 3X5Canada

化极是消除磁力异常斜磁化影响的关键步骤,可以在波数域(频率域)和空间域中实现.相比于空间域,在波数域(频率域)进行化极简单且高效,但在低纬度地区存在不稳定性问题,因此明确低纬度地区的范围,研究稳定、实用、精度高的低纬度地区化极... 详细信息

化极是消除磁力异常斜磁化影响的关键步骤,可以在波数域(频率域)和空间域中实现.相比于空间域,在波数域(频率域)进行化极简单且高效,但在低纬度地区存在不稳定性问题,因此明确低纬度地区的范围,研究稳定、实用、精度高的低纬度地区化极方法具有重要意义.本文通过理论研究得出化极因子振幅的最大值为2时,对应的磁化倾角的值为±45°,当磁化倾角在该范围内时,引起化极不稳定.因此采用正则化思想,提出了自适应正则化滤波化极方法(ARF-RTP),该方法利用化极因子振幅构建正则化滤波函数,并以振幅值等于2作为约束计算化极方法的参数值,从而实现自适应化极处理,提高了化极方法的稳定性及实用性.同时结合迭代算法提高了此方法的精度,有效地解决了低纬度地区化极的不稳定性问题.自适应正则化滤波这一思想不但可以解决化极的不稳定性问题,而且可以解决分量转换或者磁化方向转换的不稳定性问题以及类似数据处理中的不稳定性问题,具有广阔的推广应用前景.

关键词：化极低纬度地区振幅自适应正则化滤波迭代算法

维普期刊数据库博看期刊

Two-stage dynamic recrystallization and texture evolution in Al-7Mg alloy during hot torsion

在线全文

学校读者我要写书评

暂无评论

International journal of Minerals,Metallurgy and Materials 2024年第8期31卷 1900-1911页

作者： Kwang Tae Son chang Hee Cho Myoung Gyun kim ji Woon Lee School of Mechanical Industrialand Manufacturing EngineeringOregon State UniversityCorvallis OR 97331USA Department of Materials Science Engineering Northwestern UniversityEvanston IL 60208USA Research Institute of Industrial Science and Technology(RIST) Pohang 37673Rep.of Korea Division of Advanced Materials Engineering Kongju National UniversityCheonan 31080Rep.of Korea Center for Advanced Materials and Parts of Powders Kongju National UniversityCheonan 31080Rep.of Korea

Hot torsion tests were performed on the Al-7Mg alloy at the temperature ranging from 300 to 500℃ and strain rates between 0.05 and 5 s^(-1) to explore the progressive dynamic recrystallization(DRX)and texture *** DRX behavior of the alloy manifested two distinct stages:Stage 1 at strain of≤2 and Stage 2 at strains of≥*** Stage 1,there was a slight increase in the DRXed grain fraction(X_(DRX))with predominance of discontinuous DRX(DDRX),followed by a modest change in X_(DRX) until the transition to Stage *** 2 was marked by an accelerated rate of DRX,culminating in a substantial final X_(DRX) of~*** backscattered diffraction(EBSD)analysis on a sample in Stage 2 revealed that continuous DRX(CDRX)predominantly occurred within the(121)[001]grains,whereas the(111)[110]grains underwent a geometric DRX(GDRX)evolution without a noticeable sub-grain ***,a modified Avrami’s DRX kinetics model was utilized to predict the microstructural refinement in the Al-7Mg alloy during the DRX *** this kinetics model did not accurately capture the DDRX behavior in Stage 1,it effectively simulated the DRX rate in Stage *** texture index was employed to assess the evolution of the texture isotropy during hot-torsion test,demonstrating significant improvement(>75%)in texture randomness before the commencement of Stage *** initial texture evolution is attributed to the rotation of parent grains and the substructure evolution,rather than to an increase in X_(DRX).

关键词： Al-7Mg alloys hot deformation hot torsion tests dynamic recrystazlliation microstructure texture

Recent developments in selective laser processes for wearable devices

在线全文

学校读者我要写书评

暂无评论

Bio-Design and Manufacturing 2024年第4期7卷 517-547页

作者： Youngchan kim Eunseung Hwang chang Kai Kaichen Xu Heng Pan Sukjoon Hong Optical Nanoprocessing Lab Department of Mechanical EngineeringBK21 FOUR ERICA-ACE CenterHanyang University55 Hanyangdaehak-RoSangnok-GuAnsan 15588Republic of Korea Multiscale Manufacturing Lab J.Mike Walker’66 Department of Mechanical EngineeringTexas A&M UniversityCollege StationTX 77843USA State Key Laboratory of Fluid Power and Mechatronic Systems School of Mechanical EngineeringZhejiang UniversityHangzhou 310058China

Recently,the increasing interest in wearable technology for personal healthcare and smart virtual/augmented reality applications has led to the development of facile fabrication *** have long been used to develop original solutions to such challenging technological problems due to their remote,sterile,rapid,and site-selective processing of *** this review,recent developments in relevant laser processes are summarized under two separate ***,transformative approaches,such as for laser-induced graphene,are *** addition to design optimization and the alteration of a native substrate,the latest advances under a transformative approach now enable more complex material compositions and multilayer device configurations through the simultaneous transformation of heterogeneous precursors,or the sequential addition of functional layers coupled with other electronic *** addition,the more conventional laser techniques,such as ablation,sintering,and synthesis,can still be used to enhance the functionality of an entire system through the expansion of applicable materials and the adoption of new ***,various wearable device components developed through the corresponding laser processes are discussed,with an emphasis on chemical/physical sensors and energy *** addition,special attention is given to applications that use multiple laser sources or processes,which lay the foundation for the all-laser fabrication of wearable devices.

关键词： Selective laser process Wearable device Transformative approach Laser-induced graphene Ablation Sintering Synthesis

Trends in colorectal cancer incidence according to an increase in the number of colonoscopy cases in Korea

在线全文

学校读者我要写书评

暂无评论

World journal of Gastrointestinal Oncology 2024年第1期16卷 51-60页

作者： Ga Hee kim Yeong Chan Lee Tae jun kim Sung Noh Hong Dong Kyung chang Young-Ho kim Dong-Hoon Yang chang Mo Moon Kyunga kim Hyun Gun kim Eun-Ran kim Division of Gastroenterology Department of Internal MedicineAsan Medical CenterUniversity of Ulsan College of MedicineSeoul 05505South Korea Department of Digital Health Samsung Advanced Institute for Health Science and TechnologySungkyunkwan University School of MedicineSeoul 06351South Korea Division of Gastroenterology Department of Internal MedicineSamsung Medical CenterSungkyunkwan University School of MedicineSeoul 06351South Korea Division of Gastroenterology Department of Internal MedicineEwha Womans UniversitySeoul 07985South Korea Biomedical Statistics Center Samsung Medical CenterSeoul 06351South Korea Division of Gastroenterology Department of Internal MedicineSoonchunhyang University College of MedicineSeoul 04401South Korea

BACKGROUND The incidence of colorectal cancer(CRC)and preinvasive CRC(e.g.,early colon cancer and advanced adenoma)is gradually increasing in several *** To evaluate the trend in incidence of CRC and preinvasive CRC according to the increase in the number of colonoscopies performed in *** This retrospective cohort study enrolled Korean patients from 2002 to 2020 to evaluate the incidence of CRC and preinvasive CRC,and assess the numbers of diagnostic colonoscopies and colonoscopic ***-related complications by age group were also *** The incidence of CRC showed a rapid increase,then decreased after 2012 in the 50-75 year-age *** the study period,the rate of incidence of preinvasive CRC increased at a similar level in patients under 50 and 50-75 years of *** 2009,the increase has been rapid,showing a pattern similar to the increase in *** rate of colonoscopic polypectomy in patients aged under 50 was similar to the rate in patients over 75 years of age after *** rate of complications after colonoscopy and related deaths within 3 mo was high for those over 75 years of *** The diagnosis of preinvasive CRC increased with the increase in the number of colonoscopies *** the risk of colonoscopy-related hospitalization and death is high in the elderly,if early lesions at risk of developing CRC are diagnosed and treated under or at the age of 75,colonoscopy-related complications can be reduced for those aged 76 years or over.

关键词： Colorectal cancer Preinvasive colorectal cancer Colorectal polypectomy Colonoscopy

Inclusive quasielastic neutrino-nucleus scattering with energy density functional nuclear models

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics C 2024年第8期48卷 153-158页

作者： K.S.kim Soonchul Choi Hana Gil chang Ho Hyun School of liberal arts and science korea aerospace universitygoyang 10540korea Center for exotic nuclear studies institute for basic sciencedaejeon 34126korea Center for extreme nuclear matters korea universityseoul 02841korea Department of physics education daegu universitygyeongsan 38453korea

In this study,we calculated the inclusive charged-current neutrino-nucleus scattering from ^(40)Ar in the quasielastic *** explore the effect of uncertainties stemming from the nuclear structure,we used the KIDS(Korea-IBS-Daegu-SKKU)nuclear energy density functional and Skyrme force models,namely SLy4,SkI3,and *** models were selected to have distinct behavior in terms of the density dependence of the symmetry energy and the effective mass of the *** the charged-current neutrino scattering,the single-and double-differential cross sections were calculated for various *** cross sections are reported as a function of the incident neutrino *** theoretical cross sections were compared with experimental data,and the roles of the effective mass and symmetry energy were investigated in terms of charged-current neutrino-nucleus scattering.

关键词： energy density functional neutrino-nucleus scattering symmetry energy effective mass of the nucleon

Stable immobilization of lithium polysulfides using three-dimensional ordered mesoporous Mn_(2)O_(3) as the host material in lithium-sulfur batteries

在线全文

学校读者我要写书评

暂无评论

Carbon Energy 2024年第6期6卷 99-112页

作者： Sung joon Park Yun jeong Choi Hyun-seung kim Min joo Hong Hongjun chang janghyuk Moon Young-jun kim junyoung Mun Ki jae kim Department of Energy Science Sungkyunkwan UniversitySuwonGyeonggi-doRepublic of Korea Department of Energy Engineering Konkuk UniversitySeoulRepublic of Korea Advanced Batteries Research Center Korea Electronic Technology InstituteSeongnamRepublic of Korea Department of Future Energy Engineering Sungkyunkwan UniversitySuwonRepublic of Korea Department of Energy Systems Engineering Chung-Ang UniversitySeoulRepublic of Korea SKKU Advanced Institute of Nanotechnology Sungkyunkwan UniversitySuwonGyeonggi-doRepublic of Korea SKKU Institute of Energy Science and Technology(SIEST) Sungkyunkwan UniversitySuwonRepublic of Korea School of Advanced Materials Science and Engineering Sungkyunkwan UniversitySuwonRepublic of Korea

Lithium-sulfur batteries(LSBs)have drawn significant attention owing to their high theoretical discharge capacity and energy ***,the dissolution of long-chain polysulfides into the electrolyte during the charge and discharge process(“shuttle effect”)results in fast capacity fading and inferior electrochemical *** this study,Mn_(2)O_(3)with an ordered mesoporous structure(OM-Mn_(2)O_(3))was designed as a cathode host for LSBs via KIT-6 hard templating,to effectively inhibit the polysulfide shuttle ***-Mn_(2)O_(3)offers numerous pores to confine sulfur and tightly anchor the dissolved polysulfides through the combined effects of strong polar-polar interactions,polysulfides,and sulfur chain *** OM-Mn_(2)O_(3)/S composite electrode delivered a discharge capacity of 561 mAh g^(-1) after 250 cycles at 0.5 C owing to the excellent performance of OM-Mn_(2)O_(3).Furthermore,it retained a discharge capacity of 628mA h g^(-1) even at a rate of 2 C,which was significantly higher than that of a pristine sulfur electrode(206mA h g^(-1)).These findings provide a prospective strategy for designing cathode materials for high-performance LSBs.

关键词： host material lithium-sulfur battery ordered mesoporous structure shuttle effect transition-metal oxides

Immediate secondary rhinoplasty using a folded dermofat graft for resolving complications related to silicone implants: A case report

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World journal of Clinical Cases 2024年第14期12卷 2426-2430页

作者： Hoon kim jong Hyup kim In chang Koh Soo Yeon Lim Department of Plastic and Reconstructive Surgery Konyang University HospitalUniversity of Konyang College of MedicineMyunggok Medical Research InstituteDaejeon 35365South Korea

BACKGROUND Various surgical techniques have been developed to enhance the nose shapes of Asian *** implant augmentation rhinoplasty is widely used because it is relatively easy to perform and often yields satisfactory ***,this technique may lead to complications,including ischemia,necrosis,and *** most appropriate management of these complications,including infection,is immediate implant removal and revision surgery once the accompanying inflammation has ***,the patient may experience distress from nasal deformities during the intervention *** SUMMARY Herein,we describe the case of a patient who underwent a secondary dorsal augmentation,with a folded dermofat graft harvested from the inguinal area and simultaneous implant removal,successfully preventing dimpling of the nasal *** This surgical method can effectively manage implant-related complications following augmentation rhinoplasty using a silicone implant and provide satis-factory patient outcomes.

关键词： Complications Nose deformities Acquired Rhinoplasty Dermofat Surgery Plastic Case report

Generalized polynomial chaos expansion by reanalysis using static condensation based on substructuring

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 819-836页

作者： D.LEE S.chang j.LEE Department of Automotive Engineering Hanyang UniversitySeoul 04763Republic of Korea School of Mechanical Engineering Chungnam National UniversityDaejeon 34134Republic of Korea Department of Mechanical Robotics and Energy EngineeringDongguk UniversitySeoul 04620Republic of Korea

This paper presents a new computational method for forward uncertainty quantification(UQ)analyses on large-scale structural systems in the presence of arbitrary and dependent random *** method consists of a generalized polynomial chaos expansion(GPCE)for statistical moment and reliability analyses associated with the stochastic output and a static reanalysis method to generate the input-output data *** the reanalysis,we employ substructuring for a structure to isolate its local regions that vary due to random *** allows for avoiding repeated computations of invariant substructures while generating the input-output data *** substructuring with static condensation further improves the computational efficiency of the reanalysis without losing ***,the GPCE with the static reanalysis method can achieve significant computational saving,thus mitigating the curse of dimensionality to some degree for UQ under high-dimensional *** numerical results obtained from a simple structure indicate that the proposed method for UQ produces accurate solutions more efficiently than the GPCE using full finite element analyses(FEAs).We also demonstrate the efficiency and scalability of the proposed method by executing UQ for a large-scale wing-box structure under ten-dimensional(all-dependent)random inputs.

关键词： forward uncertainty quantification(UQ) generalized polynomial chaos expansion(GPCE) static reanalysis method static condensation substructuring