Готові списки джерел за темами / Coherence time enhancement

Зміст

Статті в журналах
Дисертації
Частини книг
Тези доповідей конференцій

Добірка наукової літератури з теми "Coherence time enhancement"

Автор: Grafiati

Опубліковано: 10 березня 2023

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями

Оберіть тип джерела:

Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Coherence time enhancement".

Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.

Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.

Статті в журналах з теми "Coherence time enhancement"

Zhao, Zhenxing, Qi Li, Zhi Xia, and Dajing Shang. "A Single-Hydrophone Coherent-Processing Method for Line-Spectrum Enhancement." Remote Sensing 15, no. 3 (January 22, 2023): 659. http://dx.doi.org/10.3390/rs15030659.

Повний текст джерела

Анотація:

Improving the line-spectrum detection capability of a single hydrophone is of great significance for the passive detection of small underwater platforms. In this paper, we propose a single-hydrophone cross-power spectrum (SHCS) method based on time-domain coherence. This method uses the coherence of the line spectrum and the non-coherence of the continuous spectrum noise to obtain coherent gain and improve the signal-to-noise ratio (SNR) of the line spectrum. The effects of the input SNR, number of averaging operations, and overlap ratio on the performance of the SHCS method under a background of Gaussian white noise are simulated and analyzed. The results show that when the overlap ratio is 0 and the number of averaging operations reaches saturation, the SHCS method can achieve the best performance and about 15 dB coherence gain is obtained. The performance of the SHCS method was verified by sea experiments. Under the extremely low input SNR, in which the line spectrum was almost completely submerged in the marine environmental noise, the SHCS method can obtain about 10 dB coherence gain. Under the conventional input SNR, in which the line spectrum could be observed, the SHCS method can obtain about 13 dB coherence gain. The results of processing the radiated noise from an actual cargo ship also demonstrate the effectiveness of the SHCS method.

Стилі APA, Harvard, Vancouver, ISO та ін.

Hammer, Horst, Silvia Kuny, and Antje Thiele. "Enhancing Coherence Images for Coherent Change Detection: An Example on Vehicle Tracks in Airborne SAR Images." Remote Sensing 13, no. 24 (December 9, 2021): 5010. http://dx.doi.org/10.3390/rs13245010.

Повний текст джерела

Анотація:

In Synthetic Aperture Radar (SAR) interferometry, one of the most widely used measures for the quality of the interferometric phase is coherence. However, in favorable conditions coherence can also be used to detect subtle changes on the ground, which are not visible in the amplitude images. For such applications, i.e., coherent change detection, it is important to have a good contrast between the unchanged (high-coherence) parts of the scene and the changed (low-coherence) parts. In this paper, an algorithm is introduced that aims at enhancing this contrast. The enhancement is achieved by a combination of careful filtering of the amplitude images and the interferometric phase image. The algorithm is applied to an airborne interferometric SAR image pair recorded by the SmartRadar experimental sensor of Hensoldt Sensors GmbH. The data were recorded during a measurement campaign over the Bann B installations of POLYGONE Range in southern Rhineland-Palatinate (Germany), with a time gap of approximately four hours between the overflights. In-between the overflights, several vehicles were moved on the site and the goal of this work is to enhance the coherence image such that the tracks of these vehicles can be detected as completely as possible in an automated way. Several coherence estimation schemes found in the literature are explored for the enhancement, as well as several commonly used speckle filters. The results of these filtering steps are evaluated visually and quantitatively, showing that the mean gray-level difference between the low-coherence tracks and their high-coherence surroundings could be enhanced by at least 28%. Line extraction is then applied to the best enhancement. The results show that the tracks can be detected much more completely using the coherence contrast enhancement scheme proposed in this paper.

Стилі APA, Harvard, Vancouver, ISO та ін.

Paolo, Agustin Di, Arne L. Grimsmo, Peter Groszkowski, Jens Koch та Alexandre Blais. "Control and coherence time enhancement of the 0–π qubit". New Journal of Physics 21, № 4 (4 квітня 2019): 043002. http://dx.doi.org/10.1088/1367-2630/ab09b0.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Rahman, Abdul Ghaffar Abdul, Zhi Chao Ong, and Zubaidah Ismail. "Enhancement of coherence functions using time signals in Modal Analysis." Measurement 44, no. 10 (December 2011): 2112–23. http://dx.doi.org/10.1016/j.measurement.2011.08.003.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Shreedhar Bhat, Gautam, Nikhil Shankar, and Issa Panahi. "Real-time joint dereverberation and speech enhancement for hearing aid applications using edge devices." Journal of the Acoustical Society of America 150, no. 4 (October 2021): A348. http://dx.doi.org/10.1121/10.0008541.

Повний текст джерела

Анотація:

In this work, we propose a joint dereverberation and speech enhancement technique for real-time applications. Speech dereverberation is based on the coherent-to-diffuse energy ratio (CDR) measured from the direction-of-arrival (DOA) dependent complex spatial coherence function. A personalized speech enhancement (SE) technique based on joint maximum a posteriori probability (JMAP) estimation that inherently accounts for the effects of changes in acoustic path and reverberation is used. The combination of these masking functions is used to enhance the speech corrupted by reverberation and noise in a frame-by-frame process. The proposed method is implemented on the smartphone (edge device), to illustrate real-time usability. The efficiency of the proposed method is evaluated using speech quality and intelligibility measures and compared with that of other benchmark techniques.

Стилі APA, Harvard, Vancouver, ISO та ін.

WANG, LI, YUBING GONG, and XIU LIN. "ENHANCEMENT OF INTRINSIC SPIKING COHERENCE BY EXTERNAL NON-GAUSSIAN NOISE IN A STOCHASTIC HODGKIN–HUXLEY NEURON." Fluctuation and Noise Letters 10, no. 04 (December 2011): 359–69. http://dx.doi.org/10.1142/s0219477511000624.

Повний текст джерела

Анотація:

In this paper, we study the effect of external non-Gaussian noise on the temporal coherence of the intrinsic spiking induced by the channel noise in a stochastic Hodgkin–Huxley neuron. It is found that, for a sufficiently large membrane patch, the intrinsic spiking coherence can be enhanced by the proper values of non-Gaussian noise's strength, correlation time, or deviation from Gaussian distribution. And that the intrinsic spiking can exhibit coherence resonance when the noise's strength is optimal. This implies that the channel noise-induced intrinsic spiking may become more or the most ordered in time with the assistance of the external non-Gaussian noise. These results show that the external non-Gaussian noise can play a constructive role for improving the time precision of information processing in stochastic neurons.

Стилі APA, Harvard, Vancouver, ISO та ін.

Nakano, Tamami, Haruhisa Ota, Nobumasa Kato, and Shigeru Kitazawa. "Deficit in visual temporal integration in autism spectrum disorders." Proceedings of the Royal Society B: Biological Sciences 277, no. 1684 (December 2, 2009): 1027–30. http://dx.doi.org/10.1098/rspb.2009.1713.

Повний текст джерела

Анотація:

Individuals with autism spectrum disorders (ASD) are superior in processing local features. Frith and Happe conceptualize this cognitive bias as ‘weak central coherence’, implying that a local enhancement derives from a weakness in integrating local elements into a coherent whole. The suggested deficit has been challenged, however, because individuals with ASD were not found to be inferior to normal controls in holistic perception. In these opposing studies, however, subjects were encouraged to ignore local features and attend to the whole. Therefore, no one has directly tested whether individuals with ASD are able to integrate local elements over time into a whole image. Here, we report a weakness of individuals with ASD in naming familiar objects moved behind a narrow slit, which was worsened by the absence of local salient features. The results indicate that individuals with ASD have a clear deficit in integrating local visual information over time into a global whole, providing direct evidence for the weak central coherence hypothesis.

Стилі APA, Harvard, Vancouver, ISO та ін.

AWSCHALOM, DAVID D. "CONTROLLING SPIN COHERENCE WITH SEMICONDUCTOR NANOSTRUCTURES." International Journal of Modern Physics B 22, no. 01n02 (January 20, 2008): 111–12. http://dx.doi.org/10.1142/s0217979208046165.

Повний текст джерела

Анотація:

We present two emerging opportunities for manipulating and communicating coherent spin states in semiconductors. First, we show that semiconductor microcavities offer unique means of controlling light-matter interactions in confined geometries, resulting in a wide range of applications in optical communications and inspiring proposals for quantum information processing and computational schemes. Studies of spin dynamics in microcavities — a new and promising research field — have revealed novel effects such as polarization beats, stimulated spin scattering, and giant Faraday rotation. Here, we study the electron spin dynamics in optically-pumped GaAs microdisk lasers with quantum wells and interface-fluctuation quantum dots in the active region. In particular, we examine how the electron spin dynamics are modified by the stimulated emission in the disks, and observe an enhancement of the spin coherence time when the optical excitation is in resonance with a high quality ( Q ~ 5000) lasing mode.1 This resonant enhancement, contrary to expectations from the observed trend in the carrier recombination time, is then manipulated by altering the cavity design and dimensions. In analogy to devices based on excitonic coherence, this ability to engineer coherent interactions between electron spins and photons may provide novel pathways towards spin dependent quantum optoelectronics. In a second example, the nitrogen-vacancy (N-V) center in diamond has garnered interest as a room-temperature solid-state system not only for exploring electronic and nuclear spin phenomena but also as a candidate for spin-based quantum information processing. Spin coherence times of up to 50 microseconds have been reported for ensembles of N-V centers and a two-qubit gate utilizing the electron spin of a N-V center and the nuclear spin of a nearby C-13 atom has been demonstrated. Here, we present experiments using angle-resolved magneto-photoluminescence microscopy to investigate anisotropic spin interactions of single N-V centers in diamond at room temperature.2 Negative peaks in the photoluminescence intensity are observed as a function of both magnetic field magnitude and angle, and can be explained by coherent spin precession and anisotropic relaxation at spin-level anticrossings. Additionally, precise field alignment with the symmetry axis of a single N-V center reveals the resonant magnetic dipolar coupling of a single "bright" electron spin of an N-V center to small numbers of "dark" spins of nitrogen defects in its immediate vicinity, which are otherwise undetected by photoluminescence. Most recently, we are exploring the possibility of utilizing this magnetic dipole coupling between bright and dark spins to couple two spatially separated single N-V center spins by means of intermediate nitrogen spins. Note from Publisher: This article contains the abstract only.

Стилі APA, Harvard, Vancouver, ISO та ін.

Ding, Xueli, Bing Jia, Yuye Li, and Huaguang Gu. "Enhancement of coherence resonance induced by inhibitory autapse in Hodgkin–Huxley model." International Journal of Modern Physics B 35, no. 07 (March 20, 2021): 2150110. http://dx.doi.org/10.1142/s0217979221501101.

Повний текст джерела

Анотація:

Inhibitory effect often suppresses electronic activities of the nervous system. In this paper, the inhibitory autapse is identified to enhance the degree of coherence resonance (CR) induced by noise in the Hodgkin–Huxley (HH) model with Hopf bifurcation from resting state to spiking with nearly fixed period [Formula: see text]. Without noise, the inhibitory autapse can induce a post inhibitory rebound (PIR) spike from the resting state at time delay approximating [Formula: see text] and can inhibit a spike of spiking at time delay approximating [Formula: see text]. In the presence of noise, CR characterized by maximal value of power spectrum of spike trains appears in a wide range of both time delay and conductance of autapse. With increasing autaptic conductance, CR degree becomes stronger for time delay approximating [Formula: see text] plus integer (from 0) multiples of [Formula: see text], because the inhibitory autaptic current pulses can induce more PIR spikes. The decrease of CR degree at time delay approximating integer (from 1) multiples of [Formula: see text] can be explained by the inhibition effect. The promotion of coherence resonance degree and the underlying PIR mechanism induced by inhibitory self-feedback extends the paradoxical phenomenon of inhibitory autapse to stochastic system and presents potential measures to modulate CR degree and information processing.

Стилі APA, Harvard, Vancouver, ISO та ін.

Abd-Elmoniem, K. Z., A. B. M. Youssef, and Y. M. Kadah. "Real-time speckle reduction and coherence enhancement in ultrasound imaging via nonlinear anisotropic diffusion." IEEE Transactions on Biomedical Engineering 49, no. 9 (September 2002): 997–1014. http://dx.doi.org/10.1109/tbme.2002.1028423.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Більше джерел

Дисертації з теми "Coherence time enhancement"

Santanni, Fabio. "Molecular approaches for the optimization of electron spin-based quantum bits and quantum logic gates." Doctoral thesis, 2022. http://hdl.handle.net/2158/1262928.

Повний текст джерела

Анотація:

This work highlights the different possibilities given by a rational chemical approach to obtain molecular-based quantum bits and quantum logic gates as an appealing and alternative platform for implementing quantum computation. This work resumes the three years of the author's work on this subject, mainly presenting and focusing on experimental results obtained for some new potential hydrogen-free molecular qubits, multi-qubit structures, and state-of-the-art EPR-based (Electron Paramagnetic Resonance) experiments on an archetypical vanadyl-based qubit.

Стилі APA, Harvard, Vancouver, ISO та ін.

Частини книг з теми "Coherence time enhancement"

Konstantinidis, Angelos. "Using SmallWorlds to Enhance Social Presence, Group Cohesion, and Group Identity in an Online Postgraduate Course." In Advances in Game-Based Learning, 92–110. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-2426-7.ch005.

Повний текст джерела

Анотація:

Online learning is proliferating in education, yet the establishment of social presence, development of group cohesion, and cultivation of a group identity can be particularly challenging. These three elements have a key role for a fruitful educational experience in online courses. The same time, research has shown that the use of Virtual Worlds (VWs) in educational contexts can sustain the sense of being and communicating with other people and it potentially increases group coherence and identity. In this chapter the use of a VW, SmallWorlds, for enhancing the aforementioned elements in a distance learning online master's course is discussed. The chapter begins by providing the definitions and importance of the three elements. Next, the rationale behind the choice of SmallWorlds is explained and its main features are presented. What follows is the presentation of the key pedagogical strategies implemented and it is examined how each of these strategies contributes to the enhancement of the three elements. Lastly, a set of suggestions are offered for implementing similar activities.

Стилі APA, Harvard, Vancouver, ISO та ін.

"Relaxation and the NOE." In Essential Mathematics for NMR and MRI Spectroscopists, 636–69. The Royal Society of Chemistry, 2016. http://dx.doi.org/10.1039/bk9781782627975-00636.

Повний текст джерела

Анотація:

The relaxation of spins to an equilibrium state makes itself apparent the first time one encounters a free induction decay (FID). The two major types of relaxation in magnetic resonance spectroscopy, T1 and T2 relaxation, are examined. Spin temperature is discussed to emphasise the flow of energy to and from spin systems during an experiment. Longitudinal (T1) relaxation is presented visually as the movement of the transverse magnetisation vector towards the equilibrium z-axis position and is modelled as an exponential process. Transverse relaxation (T2) is also shown visually as a de-coherence of the phases of the many transverse vectors representing the many spin magnetic moments in the sample and is also modelled as an exponential process. The spectral density function is derived from the Fourier transform of the autocorrelation function for stochastic molecular motions and its properties are examined. The dipolar relaxation mechanism that is dominant in solution NMR spectroscopy is discussed in detail using material from earlier chapters. The Nuclear Overhauser Enhancement (NOE) is then introduced, using the results from the dipolar relaxation section.

Стилі APA, Harvard, Vancouver, ISO та ін.

Ren, Weicai, Xiwu Li, Kai Wen, Yongan Zhang, Xinyu Lv, and Baiqing Xiong. "Effect of Retrogressions on Precipitation Characteristics and Strength Property in an Al-Zn-Mg-Cu Alloy." In Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220435.

Повний текст джерела

Анотація:

Retrogression treatment is a crucial process to obtain preferential microstructure and mechanical property for aviation Al-Zn-Mg-Cu alloys. In the current work, ramping time, preservation time and temperature were set as variations to investigate property evolution and precipitation characteristics for a commercial Al-Zn-Mg-Cu alloy. The results showed that the strength exhibited a continuously decrease trend with the enhancement of preservation temperature or the extension of preservation time. For a same strength level with different preservation temperature and time matches, GPII zone and η’ phase were detected as the main types of precipitates, which showed apparent coherency and semi-coherency with the matrix, respectively. Phases with relatively large size possessed larger proportions for higher preservation temperatures while the average grain size exhibited an increase trend. As for prolonging ramping time, similar strength degradation was observed under equivalent preservation regimes. For the same strength level with different ramping and preservation time matches, the precipitates were still GPII zone and η’ phase. With the prolonging of ramping time, the proportion of phases with relatively large size exhibited a decrease trend, so as to the average grain size (AGS). The subtle differences of precipitation characteristics and strength property matches were analyzed, which provided a promising way to improve overall performance of Al-Zn-Mg-Cu alloys.

Стилі APA, Harvard, Vancouver, ISO та ін.

Fox, Raymond. "Lesson Architecture." In The Use of Self. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780190616144.003.0013.

Повний текст джерела

Анотація:

This remark says it clearly: the best teaching sets learners on their own path to discovery. Appeal to students’ hearts as well as filling their heads; it is sustenance for their professional journey. Effective, engaging, and enjoyable lessons do not happen automatically. They take effort. They demand attention to striking the right balance between content and process, to meeting the requirements of the curriculum and the distinctive needs of students. Every course is different. Every class is organic. Every group of students is distinctive. A tightly framed lesson leaves room for the unexpected and exceptional—a corollary to the apparent paradox stated earlier—structure frees you to be spontaneous. It affords room for you to weave teachable moments into the overall fabric of the lesson. Curricula and syllabi are basically fixed, general, and inflexible. Without compromising the integrity of the prescribed content, a solidly designed lesson creatively customizes classes to reflect your particular expertise, preferences, and manner. At the same time it takes into account students’ experience, strengths, and styles. Pre-reflection lesson planning—pulling it all together, in other words—is a kind of mental rehearsal. It focuses on desired changes in students, envisions the optimal conditions for creating a context for learning, and generates a strategy to intertwine process and content into a vibrant tapestry. Weaving it together calls for a self-conscious and conscientious effort. The lesson plan takes stock of the characteristics and conditions associated with you (personality, knowledge, skills, experiences, style), with students (receptivity, motivation, attitude toward the subject, style), with classroom milieu (number of students, physical environment, room temperature, acoustics), and with varied modes of instruction. It increases the likelihood of achieving greater student participation and optimizing learning. It makes teaching more stimulating and gratifying for both students and you. A lesson plan arises from pre-reflection and buttresses both reflection-in- action, and reflection-on-action. It harnesses your ingenuity to coalesce a multitude of factors—goals, themes, patterns, assignments, exercises, and enhancement materials (e.g., handouts) into a coherent and unified presentation. The lesson plan plots a path through this complex terrain by synchronizing this panoply of variables.

Стилі APA, Harvard, Vancouver, ISO та ін.

Тези доповідей конференцій з теми "Coherence time enhancement"

Valero, Maria Luis, and Emanuel A. P. Habets. "Insight into linear periodically time-varying coherence reduction methods for stereophonic acoustic echo cancellation." In 2016 IEEE International Workshop on Acoustic Signal Enhancement (IWAENC). IEEE, 2016. http://dx.doi.org/10.1109/iwaenc.2016.7602893.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Luo, Manting, Tengfei You, Qiukun Zhang, Jianfeng Zhong, and Shuncong Zhong. "Enhancement of Time-domain Optical Coherence Tomography Images Using Stationary Wavelet Transform." In 2015 International Symposium on Computers and Informatics. Paris, France: Atlantis Press, 2015. http://dx.doi.org/10.2991/isci-15.2015.149.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Kono, Junichiro. "Ultrastrong Light-Matter Coupling in a High-Q Terahertz Cavity." In JSAP-OSA Joint Symposia. Washington, D.C.: Optica Publishing Group, 2017. http://dx.doi.org/10.1364/jsap.2017.7a_a409_1.

Повний текст джерела

Анотація:

Strong resonant light-matter coupling in a cavity setting is an essential ingredient in fundamental cavity quantum electrodynamics (QED) studies as well as in cavity-QED-based quantum information processing. In particular, a variety of solid-state cavity QED systems have recently been examined, not only for the purpose of developing scalable quantum technologies, but also for exploring novel many-body effects inherent to condensed matter. For example, collective N1/2-fold enhancement of light-matter coupling in an N-body system, combined with colossal dipole moments available in solids, compared to traditional atomic systems, is promising for entering uncharted regimes of ultrastrong light-matter coupling. Nonintuitive quantum phenomena can occur in such regimes, including a squeezed vacuum state, the Dicke superradiant phase transition, the breakdown of the Purcell effect, and quantum vacuum radiation induced by the dynamic Casimir effect. However, creating a system that combines a long electronic coherence time, a large dipole moment, and a high cavity quality (Q) factor has been a challenging goal.

Стилі APA, Harvard, Vancouver, ISO та ін.

Robinson, Brent W., and Mohammad Saquib. "Adaptive coherent averaging for real-time electrocardiogram enhancement." In 2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC). IEEE, 2014. http://dx.doi.org/10.1109/embc.2014.6944759.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Sulimany, Kfir, Rom Dudkiewicz, Simcha Korenblit, Hagai S. Eisenberg, Yaron Bromberg, and Michael Ben-Or. "High-Dimensional Quantum Key Distribution with Scrambled Time-Bin Encoding." In Quantum 2.0. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/quantum.2022.qm3b.7.

Повний текст джерела

Анотація:

We propose and analyze a high-dimensional cryptographic protocol relying on a coherent-one-way quantum key distribution system. We demonstrate it over a 40km fiber link and observe a twofold enhancement in the secure key rate.

Стилі APA, Harvard, Vancouver, ISO та ін.

Soutar, C., Z. Q. Wang, C. M. Cartwright, and W. A. Gillespie. "Real-Time Optical Intensity Correlator using Photorefractive BSO and a Liquid Crystal Television." In Photorefractive Materials, Effects, and Devices II. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/pmed.1991.tub3.

Повний текст джерела

Анотація:

The use of photorefractive Bi12SiO20 (BSO) as a dynamic holographic medium in optical processing systems has been the subject of much activity. Typical operations carried out include edge enhancement [1], novelty filtering [2] and the correlation of optical signals [3]. However the use of BSO in coherent correlator systems is hindered by positional problems [3,4] as the crystal must be inserted at the Fourier plane of the transforming lens(es) to a high degree of accuracy (to within 0.5 % of the focal length of the lens as determined in ref 3).

Стилі APA, Harvard, Vancouver, ISO та ін.

Mukherjee, A., N. Mukherjee, G. Arzumanyan, and J. C. Diels. "Coherent Multiphoton Resonant Interaction And Harmonic Generation." In International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/up.1986.md7.

Повний текст джерела

Анотація:

As a succession of two pulses propagates through a medium which exhibits a resonance (single or multiphoton), the resonant parts of the susceptibility will depend on the relative phase of the two pulses, provided the delay between the pulses is shorter than the phase relaxation time of the interaction. As a result of this "coherent interaction", the reradiation of the sample (the fluorescence, the absorption and the generation of harmonics) will be a periodic function of the phase difference and delay between the two pulses of the sequence 1. The study of these coherent effects is important, because one expect to find conditions under which the maximum harmonic conversion to much shorter wavelengths can be greatly enhanced 2. The presence of the multiphoton resonance enhances the nonlinear susceptibility responsible for the harmonic generation, but reduces also the maximum achievable conversion efficiency because of resonant losses (depletion of the fundamental by multiphoton absorption). The latter effect can be eliminated by a judicious choice of the pulse sequencing and phasing. In addition to demonstrating, for the first time, coherent interaction enhancement in harmonic generation, the data of third harmonic versus relative phase of the pulse sequences enable us to measure the phase angle of the third order susceptibility (hence the contribution of the continuum relative to that of the resonance).

Стилі APA, Harvard, Vancouver, ISO та ін.

Amini, Noushin, and Yassin A. Hassan. "Fluid Flow Mixing of Turbulent Jets Within a Staggered Rod Bundle." In ASME 2012 Fluids Engineering Division Summer Meeting collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/fedsm2012-72482.

Повний текст джерела

Анотація:

In this investigation, flow mixing between turbulent jets injecting to a channel containing a rod bundle and the channel flows is studied using Particle Image Velocimetry (PIV) and Matched Index of Refraction (MIR) techniques. A specific case of a single impinging jet with a Reynolds number of 13,400 is considered for this analysis. The time-averaged vorticity fields for three different planes within the measurement volume verify the presence of coherent structures within all three fields, specifically in areas close to the jet impingement area and in the shear layer of the jet within the impingement plane. The cumulative effect of the vorticity patterns observed within all measurement planes is believed to have a significant role in the enhancement of mixing within the test section. To further analyze the behavior of the large-scale coherent structures observed in the time-averaged vorticity fields, Proper Orthogonal Decomposition (POD) technique was applied to the PIV velocity fields. The results confirm that the jet flow is the most energetic and the dominant feature of the flow field. Therefore, to further analyze the behavior of some of the relatively smaller-scale coherent structures which could play a significant role in the mixing process, a higher number of modes or a different approach needs to be considered.

Стилі APA, Harvard, Vancouver, ISO та ін.

Rogovin, D., J. Scholl, R. Pizzoferrato, M. DeSpirito, M. Marinelli, and U. Zammit. "Stark-enchanced nonlinear optics in shaped microparticle suspensions: beam combination." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.fz3.

Повний текст джерела

Анотація:

Electromagnetic alignment of the microparticles, by either a uniform electric field or polarized radiation, changes the gain spectrum for energy transfer via nondegenerate two-wave mixing in three distinct ways: (1) the low frequency peak of the gain spectrum, arising from the translational grating, is enhanced, (2) the high frequency portion of the gain, arising from the orientational grating, is enhanced, and (3) the high frequency portion of the gain spectrum is upshifted so that the orientational peak will occur at higher frequencies. The blue shift in the orientational peak arises because microparticle alignment reduces the rotational response time. The enhancement of the low frequency portion of the gain spectrum arises from the formation of an additional density grating that possesses some orientational characteristics. Enhancement of the high frequency orientational portion of the gain spectrum arises from two causes: the orientational grating is made deeper when the microparticles are aligned, and the formation of an additional orientational grating that has some translational characteristics. This feature of the suspension’s nonlinear electrodynamics reflects the appearance of new coherent scattering mechanisms resulting from the loss of symmetry in the presence of either a uniform electric field or polarized radiation.

Стилі APA, Harvard, Vancouver, ISO та ін.

Nagatsu, Akihito, and Hideo Suzuki. "Directional-edge-segment detection based on edge enhancement of FLC-SLM and optical spatial filtering." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/oam.1993.mzz.9.

Повний текст джерела

Анотація:

A new method is developed to detect edges and their directional edge segments from real objects based on edge enhancement of a ferroelectric liquid-crystal spatial light modulator (FLC-SLM) and optical spatial filtering. Real image of an object is written onto a FLC-SLM through a camera lens and incoherent-coherent image conversion is performed. Edge enhancement can be performed on the same FLC-SLM, when the alignment direction is coincident with the direction of polarization of read-out light. Resultant image has bright (or dark) edges with thin width. Next, directional edge segments with any size and angle can be extracted using optical spatial filtering, which is realized by the other FLC-SLM. To confirm availability of this method, we constructed a prototype system. Resolution of the FLC-SLM we used is more than 30 1p/mm and available area is 15mm by 15mm square. Both FLC-SLMs can be operated by synchronized mode with 1kHz clock. Processing speed of the system is 30 to 200 times faster than that of an electric processing. Experimental results and system evaluation are presented.

Стилі APA, Harvard, Vancouver, ISO та ін.

Ми пропонуємо знижки на всі преміум-плани для авторів, чиї праці увійшли до тематичних добірок літератури. Зв'яжіться з нами, щоб отримати унікальний промокод!