Log in

Relevant bibliographies by topics / +621.383]

Academic literature on the topic '+621.383]'

Author: Grafiati

Published: 30 May 2022

Last updated: 31 May 2022

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Contents

Journal articles
Dissertations / Theses
Book chapters

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic '+621.383].'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "+621.383]"

1

Zheng, Jian Xin, Jie Han, and Chuan Shao Liu. "Numerical Design of Stepped Compound Horn with Longitudinal-Torsional Vibration under Single Acoustic Excitation." Key Engineering Materials 621 (August 2014): 385–91. http://dx.doi.org/10.4028/www.scientific.net/kem.621.385.

Full text

Abstract:

The mechanism of longitudinal-torsional vibration (LTV) realized by using converter with multiple diagonal slits (MDS) was analyzed based on the acoustic wave propagation when acoustic wave enters obliquely from steel to air. The influences of geometrical parameters of the stepped compound horn with multiple diagonal slits on natural frequencies of LTV were studied with finite element analysis (FEA). The design procedure of stepped compound horn with LTV was provided. The vibration characteristics of actual horn were analyzed with simulation and test. The FEA results show that LTV of the output end of the stepped compound horn may be realized when the input end is excited by longitudinal vibration at certain natural frequency if suitable geometrical dimensions are selected, and the amplitude of the horn is periodical; the trajectory of the particle in the output end is helical curve. The test results indicate that LTV may be realized by stepped compound horn under single acoustic excitation, and the vibration frequency is close to the simulation result, and its vibration properties are good. This method may be applied to design the acoustics system of ultrasonic machining with LTV under single acoustic excitation.

APA, Harvard, Vancouver, ISO, and other styles

2

Li, Yu, and Ping Yan Bian. "A Strategy for On-Line Monitoring the Crosslinking Degree of 3D Printing Hydrogel Fiber Based on Dual-Threshold Enhancement Method." Key Engineering Materials 621 (August 2014): 38–43. http://dx.doi.org/10.4028/www.scientific.net/kem.621.38.

Full text

Abstract:

The optical detection of the crosslinking degree is very important to the forming quality’s on-line control of the hydrogel fibers and tissue engineering scaffolds in 3D printing process at room temperature. For the feature of small scale object, low contrast ratio and unclear outline of the crosslinked area, we processed the crosslinking image with the dual-threshold enhancement method. Firstly, the color image is decomposed into three two–dimensional RGB signals. Secondly, the RGB signals are processed through wavelet transform respectively, and those wavelet coefficients are amplified or reduced with dual-threshold method for the purpose of enhancement and denoising. Then, the new RGB signals are reconstructed by those wavelet coefficients. At last, the new RGB signals are regrouped to get enhanced crosslinking image. Experimental results show that, after processed with this method, the image has a strong sense of color gradation, the details of image are outstanding, and the distinction of the crosslinked zone of the hydrogel fiber is obvious. Moreover, measurement precision of crosslinking degree is improved by 4.58%. This is helpful to improve the performance of the real-time control of crosslinking process.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic "+621.383]"

1

Євтушенко, Ігор Олександрович. "Датчик інфрачервоного випромінювання." Master's thesis, КПІ ім. Ігоря Сікорського, 2019. https://ela.kpi.ua/handle/123456789/30579.

Full text

Abstract:

В магістерській дисертації проведено огляд науково-технічної літератури по призначенню та конструкції датчиків інфрачервоного випромінювання. Показано перспективами використання нітриду галію в електронній техніці для виробництва побутових та промислових датчиків інфрачервоного випромінювання. Проведено аналіз впливу конструктивних особливостей на перспективу розвитку датчиків ІЧ випромінювання. Розглянуті перспективні технології для створення ефективних датчиків. Розроблене експериментальне устаткування для дослідження росту епітаксіальних плівок GаN і AlxGa1-xN та виміру параметрів плівок. Запропонована методика розрахунку параметрів епітаксіальних плівок.
In the master's thesis the review of scientific and technical literature on the purpose and design of infrared radiation sensors was carried out. Prospects for the use of gallium nitride in electronic technology for the production of household and industrial infrared radiation sensors are shown. The influence of design features on the perspective of the development of IR radiation sensors is analyzed. Advanced technologies for creating effective sensors are considered. Experimental equipment for the growth of epitaxial GaN and AlxGa1-xN films and measurement of film parameters has been developed. The method of calculation of parameters of epitaxial films is offered.

APA, Harvard, Vancouver, ISO, and other styles

2

Суховій, Ніна Олегівна. "Нанотемплети для гетероструктур нітридів III групи." Doctoral thesis, Київ, 2018. https://ela.kpi.ua/handle/123456789/24998.

Full text

Abstract:

Дисертаційна робота присвячена комплексному дослідженню застосувань і розробок технологічних рішень щодо формування нанотемплетів для гетероструктур ІІІ-нітридів, в тому числі з неполярною кристалографічною орієнтацією, щодо забезпечення малодефектності і можливості одержання наноструктур (наностержнів, квантових точок, тощо) для їх практичної реалізації в оптоелектронних інтегральних схемах. В ході досліджень для нітрид галію неполярної (112̅0) орієнтації з використанням нанотемплетів анодованого оксиду алюмінію на Si(100) одержано щільність дислокацій 3х106 см-2, що дає змогу формувати InGaN/GaN КЯ і КТ з підвищеним вмістом індію. Згідно запропонованої спрощеної математичної моделі, встановлено, що може бути забезпечена низька щільність дислокацій при будь-якій глибині пір при радіусах пір < 10 нм, одержання яких за допомогою нанотемплетів анодного оксиду алюмінію дуже проблематично. Проте, для MOCVD епітаксії були експериментально визначені термодинамічні параметри (температура, тиск) та прекурсори, при яких на поверхні сапфіру утворюються нанопори з радіусом <10нм. На одержаних темплетах нанотекстурованого сапфіру була показана можливість в одному технологічному циклі вирощувати гетероепітаксійні шари ІІІ-нітридів з низькою щільністю дислокацій (~ 5 х 106 см-2). Ключові слова: нанотемплети, гетероструктури, нітриди ІІІ групи, малодефектність, анодований оксид алюмінію.

APA, Harvard, Vancouver, ISO, and other styles

3

Amri, Hedi. "Un nouveau protocole basé sur la réduction et l'agrandissement des images REPro (Reduction/Expansion Protocol) : appliccation : transmission et archivage pour le télédiagnostic médical." Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2059.

Full text

Abstract:

L'échange des images médicales est l'un des obstacle majeurs dans une application de télémédecine vu le grand volume de ces images et la limitation des la bande passante allouée à cette application. Pour contourner ce problème, nous adoptons un nouveau protocole de transmission des images médicales qui consiste à réduire l'image avant de l'emettre et à l'agrandir lors de la réception (protocole " REPro": Réduction Expansion Protocole
The exchang of medical exchange is one of the major obstacles in a telemedicine

APA, Harvard, Vancouver, ISO, and other styles

4

Sujka, Marta. "Alignment and rectifying properties of donor-electron bridge-acceptor molecules." Thesis, Cranfield University, 2007. http://hdl.handle.net/1826/2295.

Full text

Abstract:

Molecular electronics based on the bottom-up approach appears to be a promising alternative to overcome the limitations of the top-down lithographic fabrication of electronic devices. The ability to manipulate single or small groups of molecules provides a great opportunity to build electronic devices at the molecular level. However, before any device can be constructed, it is vital to understand the parameters that control the device properties such as: molecular structure, conformation and arrangement at the surface, the molecule-substrate and molecule-electrode interactions. This thesis presents an investigation of the alignment of acceptor-electron bridge-donor structures and describes how the molecular structure and arrangement affect rectifying properties of the monolayers. Studies included typical Langmuir-Blodgett (LB), chevron-shaped, and ionically coupled structures that were characterised using various techniques, such as Quartz Crystal Microbalance (QCM), Surface Plasmon Resonance (SPR), Second Harmonic Generation (SHG) and Scanning Tunnelling Spectroscopy (STS). The results obtained showed that to achieve high rectification the molecules must form ordered and stable monolayers that are able to withstand the electric field applied to the junction. It was also shown that due to the disordered monolayer formation and presence of certain ions, it was extremely difficult to state without doubt whether the rectification was a result of the donor-electron bridge-acceptor structure proposed by Aviram and Ratner1. Studies of chevron-shaped molecules confirmed the possibility of depositing them using the LB technique. However, the reduction of long aliphatic chains was very likely balanced by the formation of less ordered or unstable monolayers. The highest rectification ratio of 30 ± 3 at ± 1 V was obtained for 1-butyl-2,6-bis-[2-(4- dibutylamino-phenyl)-vinyl]-pyridinium iodide (dye 7) and the origin of the I-V asymmetry was attributed to back electron transfer from iodide to pyridinium ring. Although dye 1-butyl-2,6-bis-(2-{4-[2-(4-dibutylamino-phenyl)-ethyl]-phenyl}-vinyl)- pyridinium iodide (dye 9) showed electrical asymmetry (RR=16 at plus/minus 1 V) shortly after deposition onto the gold-coated highly oriented pyrolytic graphite (HOPG), it seemed to form an unstable alignment and as a consequence the rectification decayed over a period of a few hours. Improved ordering, stability, and rectification were achieved from ionically coupled structures, where the monolayers were formed using chemisorption and ionic assembly instead of physisorption.

APA, Harvard, Vancouver, ISO, and other styles

5

Bruno, Davide. "Geosynchronous synthetic aperture radar : design and applications." Thesis, Cranfield University, 2009. http://dspace.lib.cranfield.ac.uk/handle/1826/5618.

Full text

Abstract:

Synthetic Aperture Radar (SAR) imaging from geosynchronous orbit has significant potential advantages over conventional low-Earth orbit (LEO) radars, but also challenges to overcome. This thesis investigates both active and passive geosynchronous SAR configurations, presenting their different features and advantages. Following a system design trade-off that involved phase uncertainties, link budget, frequency and integration time, an L band bi-static configuration with 8-hour integration time that reuses the signal from a non-cooperative transmitter has been presented as a suitable solution. Cranfield Space Research Centre looked into this configuration and proposed the GeoSAR concept, an L band bi-static SAR based on the concept by Prati et al. (1998). It flies along a circular ground track orbit, reuses the signal coming from a noncooperative transmitter in GEO and achieves a spatial resolution of about 100 m. The present research contributes to the GeoSAR concept exploring the implications due to the 8-hour integration time and providing insights about its performance and its possible fields of application. Targets such as canopies change their backscattered phase on timescales of seconds due to their motion. On longer time scales, changes in dielectric properties of targets, Earth tides and perturbations in the structure of the atmosphere contribute to generate phase fluctuations in the collected signals. These phenomena bring temporal decorrelation and cause a reduction in SAR coherent integration gain. They have to be compensated for if useful images are to be provided. A SAR azimuth simulator has been developed to study the influence of temporal decorrelation on GeoSAR point spread function. The analysis shows that ionospheric delay is the major source of decorrelation; other effects, such as tropospheric delay and Earth tides, have to be dealt with but appear to be easier to handle. Two different options for GeoSAR interferometry have been discussed. The system is well suited to differential interferometry, due to the short perpendicular baseline induced by the geometry. A GeoSAR has advantages over a Low Earth Orbit (LEO) SAR system to monitor processes with significant variability over daily or shorter timescales (e.g. soil moisture variation). This potential justifies further study of the concept.

APA, Harvard, Vancouver, ISO, and other styles

6

Blair, Christopher Douglas. "Multipoint communication protocols : a transport service for real-time group interaction." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359664.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Erbinger, Lawrence. "On the potential for high speed communication over the subscriber loop." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260511.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Saka, Franklin. "Ethernet for the ATLAS second level trigger." Thesis, Royal Holloway, University of London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395390.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Martin, Thomas. "A set theoretic approach to broadcast encryption." Thesis, Royal Holloway, University of London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415905.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Ho, Lester Tse Wee. "Self-organising algorithms for fourth generation wireless networks and its analysis using complexity metrics." Thesis, Queen Mary, University of London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407388.

Full text

APA, Harvard, Vancouver, ISO, and other styles

More sources

Book chapters on the topic "+621.383]"

1

"Communication in the Presence of NoiseDecimal classification: 621.38. Original manuscript received by the Institute, July 23, 1940. Presented, 1948 IRE National Convention, New York, N. Y., March 24, 1948; and IRE New York Section, New York, N. Y., November 12, 1947." In Claude E. Shannon. IEEE, 2009. http://dx.doi.org/10.1109/9780470544242.ch6.

Full text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!