Dissipative Effects on Quantum Sticking

Using variational mean-field theory, many-body dissipative effects on the threshold law for quantum sticking and reflection of neutral and charged particles are examined. For the case of an ohmic bosonic bath, we study the effects of the infrared divergence on the probability of sticking and obtain a non-perturbative expression for the sticking rate. We find that for weak dissipative coupling $\alpha$, the low energy threshold laws for quantum sticking are modified by an infrared singularity in the bath. The sticking probability for a neutral particle with incident energy $E\to 0$ behaves asymptotically as ${\it s}\sim E^{(1+\alpha)/2(1-\alpha)}$; for a charged particle, we obtain ${\it s}\sim E^{\alpha/2(1-\alpha)}$. Thus, "quantum mirrors" --surfaces that become perfectly reflective to particles with incident energies asymptotically approaching zero-- can also exist for charged particles.Comment: 10 pages, 0 fig

Analyze and modelingofdamage behavior of a C0.12%Mn1.02%Si0.29% HLE steel solicited in selected physicochemical medium

The influence of environment and physical parameters on C0.12%Mn1.02%Si0.29% HLE steel steel corrosion damage behaviour in NaCl solutions was studied using weight loss, pH evolution at 300k to 370k, electro-exchanges, and passivity. Herein, the results show that the corrosion rate changes versus type of thermal treatment and cooling fluid, solution concentration, shape, size and cooling speed of the samples. The resolution of Nernst equation proves that the increase in temperature has a direct effect on hydrogen potential of the solution, current and corrosion potential of the metal. Moreover, the inhibition efficiency was determined by theoretical calculation using mechanical molecular and semi-empirical method. These results guided us to conclude that the inhibitor, which has low electronegativity than C0.12%Mn1.02%Si0.29% Steel has good efficienc

Correlation between surface tension, work of adhesion in liquid metals/ceramic systems, and acoustic parameters

In the paper, a correlation between acoustic velocities V, elastic moduli M, and densities ρ, with surface tension σm, and work of adhesion Wad of different liquid metals on a given ceramic is studied and demonstrated. Simulation program is developed and used for scanning acoustic microscopy (SAM) under operating conditions, which favour the generation of acoustic waves. As found, for the given systems, all investigated acoustic parameters exhibit good dependences with both σm and Wad. Analysis and quantification of the results lead to the determination of semi-empirical formulas.В статті вперше демонструється кореляція між акустичними швидкостями V, пружніми модулями M, густинами ρ та поверхневим натягом σm, а також роботою адгезії Wad різних рідких металів на фіксованій кераміці. Використовується обчислювальна програма для сканувального акустичного мікроскопу (САМ) за умов, що є сприятливими задля ґенерування акустичних хвиль. Виявлено, що для конкретних систем усі досліджені акустичні параметри демонструють хорошу залежність від поверхневого натягу та роботи адгезії. Аналіза та кількісне визначення результатів привели до встановлення напівемпіричних формул.В статье исследуется и впервые демонстрируется корреляция между акустическими скоростями V, упругими модулями M, плотностями ρ и поверхностным натяжением σm, а также работой адгезии Wad различных жидких металлов на фиксированной керамике. Используется вычислительная программа для сканирующего акустического микроскопа (САМ) в условиях, благоприятных для генерирования акустических волн. Обнаружено, что для конкретных систем все исследованные акустические параметры демонстрируют хорошую зависимость от поверхностного натяжения и работы адгезии. Анализ и количественное определение результатов привели к установлению полуэмпирических формул

Orthogonality Catastrophe in Quantum Sticking

The probability that a particle will stick to a surface is fundamental to a variety of processes in surface science, including catalysis, epitaxial growth, and corrosion. At ultralow energies, how particles scatter or stick to a surface affects the performance of atomic clocks, matter-wave interferometers, atom chips and other quantum information processing devices. In this energy regime, the sticking probability is influenced by a distinctly quantum mechanical effect: quantum reflection, a result of matter wave coherence, suppresses the probability of finding the particle near the surface and reduces the sticking probability. We find that another quantum effect can occur, further shaping the sticking probability: the orthogonality catastrophe, a result of the change in the quantum ground state of the surface in the presence of a particle, can dramatically alter the probability for quantum sticking and create a superreflective surface at low energies.Comment: 10 pages, 2 figure

Assessment of dysarthric speech through rhythm metrics

AbstractThis paper reports the results of acoustic investigation based on rhythmic classifications of speech from duration measurements carried out to distinguish dysarthric speech from healthy speech. The Nemours database of American dysarthric speakers is used throughout experiments conducted for this study. The speakers are eleven young adult males with dysarthria caused by cerebral palsy (CP) or head trauma (HT) and one non-dysarthric adult male. Eight different sentences for each speaker were segmented manually to vocalic and intervocalic segmentation (176 sentences). Seventy-four different sentences for each speaker were automatically segmented to voiced and non-voiced intervals (1628 sentences). A two-parameters classification related to rhythm metrics was used to determine the most relevant measures investigated through bi-dimensional representations. Results show the relevance of rhythm metrics to distinguish healthy speech from dysarthrias and to discriminate the levels of dysarthria severity. The majority of parameters was more than 54% successful in classifying speech into its appropriate group (90% for the dysarthric patient classification in the feature space (%V, ΔV)). The results were not significant for voiced and unvoiced intervals relatively to the vocalic and intervocalic intervals (the highest recognition rates were: 62.98 and 90.30% for dysarthric patient and healthy control classification respectively in the feature space (ΔDNV, %DV))

Influence of Boron Adding on the Acoustic Materials Signature Curves for Computing of Surface Acoustic Wave Velocities of Ti64 Alloys

The effect of Boron admixture with five different concentrations x = 0.0, 0.04, 0.09, 0.30 and 0.55% wt. B on elastic properties of Ti–6Al–4V alloy is investigated. The values of velocities of propagating surface acoustic wave as well as bulk wave for additional structures are deduced. As found, with the increasing of Boron content in Ti–6Al–4V alloy, its acoustic material signature (Young’s modulus E, shear modulus G, bulk modulus B), longitudinal velocities, and shear velocities increase from 113 to 126 GPa, from 42.5 to 47.4 GPa, from 110.8 to 123.5 GPa, from 6148 to 6492 m/s, from 3097 to 3171 m/s, respectively. Using angular spectrum model, we calculate the reflectance function and the acoustic materials signature of Ti–6Al–4V–xB, which show an oscillatory behaviour. The spectral treatment of these signatures provides the exact definition of Rayleigh wave velocity.Исследовано влияние примеси бора при пяти значениях концентрации x = 0,0, 0,04, 0,09, 0,30 и 0,55% масс. B на упругие свойства сплава Ti–6Al–4V. Определены значения скоростей распространяющейся поверхностной акустической волны, а также объёмной акустической волны для дополнительных структур. Установлено, что при увеличении содержания бора в сплаве Ti–6Al–4V акустические характеристики материала (модуль Юнга E, модуль сдвига G, объёмный модуль B), продольные скорости и скорости сдвига увеличиваются от 113 до 126 ГПа, от 42,5 до 47,4 ГПа, от 110,8 до 123,5 ГПа, от 6148 до 6492 м/с, от 3097 до 3171 м/с соответственно. С использованием модели углового спектра вычислены функция отражения и акустические характеристики материала Ti–6Al–4V–xB, которые проявляют осциллирующее поведение. Спектральная обработка этих характеристик позволяет точно определить скорость волны Рэлея.Досліджено вплив домішки Бору за п’ятьох значень концентрації x = 0,0, 0,04, 0,09, 0,30 та 0,55% мас. B на пружні властивості стопу Ti–6Al–4V. Визначено значення швидкостей поширюваної поверхневої акустичної хвилі, а також об’ємної акустичної хвилі для додаткових структур. Встановлено, що при збільшенні вмісту Бору в стопі Ti–6Al–4V акустичні характеристики матеріялу (модуль Юнґа E, модуль зсуву G, об’ємний модуль B), поздовжні швидкості та швидкості зсуву збільшуються від 113 до 126 ГПа, від 42,5 до 47,4 ГПа, від 110,8 до 123,5 ГПа, від 6148 до 6492 м/с, від 3097 до 3171 м/с відповідно. З використанням моделю кутового спектру розраховано функцію відбивання й акустичні характеристики матеріялу Ti–6Al–4V–xB, які проявляють осцилівну поведінку. Спектральна обробка цих характеристик забезпечує можливість точного визначення швидкости Релейової хвилі

Effects of Al Content on Elastic Parameters of AlxGa1-xAs (0 ≤ x ≤ 1) Alloys

131-137Elastic parameters of AlxGa1-xAs (0 ≤ x ≤ 1) alloys are numerically determined and analyzed on the basis of scanning acoustic microscopy technique. Thus, the dependence of Al concentrations, x, on all features of reflection coefficient and acoustic materials signatures (critical angles of reflected modes, spatial periods, peaks of FFT spectra and their corresponding wave velocities) has been considered, analyzed and discussed. It is found that as Al content increases several behaviors are obtained: (i) all critical angles of longitudinal, transverse and Rayleigh waves, decrease, (ii) all spatial periods increase and (ii) both Rayleigh and longitudinal wave velocities increase. Moreover, the variations of these parameters, P, were quantified and semi-empirical formulas were found to be of the form: P = c + ax + bx2; from these formulas, valuable information can be derived and may be useful for AlxGa1-xAs compositional characterization

COMPRESSION D’IMAGES FIXES BIOMEDICALES PAR TRANSFORMEE EN ONDELETTES, QUANTIFICATION VECTORIELLE ET CODAGE ENTROPIQUE

Dans ce travail, nous nous intéressons à la compression d’images biomédicales fixes par différents types de latransformée en ondelettes discrètes, associés à différents algorithmes de quantification vectorielle et de codageentropique.Ce type de compression nous a permis de déterminer la qualité des images reconstruites (PSNR) et le taux decompression (TC) correspondants selon le type de l’ondelette et les algorithmes de QV et de codage entropiqueutilisés.Une étude comparative a été menée dans le but de déterminer les méthodes conduisant aux meilleurs résultatspossibles

Characterization of Single SAW Velocities of Ti–6Al–4V Alloy as a Function of Porosity by SAM Simulation for Applications

Rayleigh wave modes depend on porosity of Ti–6Al–4V alloy with porosities between 60–75%. It is very important in many applications and understanding of bonding arrangements at propagating surface acoustic-wave velocities. These velocities are deduced from the analysis of the topped acoustic signatures’ curves obtained by recording the output signal VV. We used simulation of acoustic microscopy to measure Rayleigh velocities. The acoustic parameters were determined as follow: longitudinal (VL), transverse (VT), and Rayleigh (VR) velocities from 1139 ms⁻¹ to 285 ms⁻¹, from 87 ms⁻¹ to 143 ms⁻¹, and from 562 ms⁻¹ to 136 ms⁻¹, respectively, for porosity from 60% to 75%.Режимы волн Рэлея зависят от пористости сплава Ti–6Al–4V, которая составляет 60–75%. Это очень важно для многих приложений и понимания связующих устройств при распространении поверхностных акустических волн. Скорости определялись с помощью анализа усечённых кривых акустических характеристик, полученных путём регистрации выходного сигнала VV. Моделированием поверхностных акустических волн измерялись скорости Рэлея. Определены акустические параметры: продольные (VL), поперечные (VT) скорости и скорость Рэлея (VR) — от 1139 мс⁻¹ до 285 мс⁻¹, от 87 мс⁻¹ до 143 мс⁻¹ и от 562 мс⁻¹ до 136 мс⁻¹ соответственно (при пористости от 60% до 75%).Режими Релейових хвиль залежать від пористости стопу Ti–6Al–4V, яка становить 60–75%. Це дуже важливо для багатьох застосувань і розуміння сполучних пристроїв при поширенні поверхневих акустичних хвиль. Швидкості визначалися за допомогою аналізи усічених кривих акустичних характеристик, одержаних шляхом реєстрації вихідного сиґналу VV. Моделюванням поверхневих акустичних хвиль вимірювалися Релейові швидкості. Визначено акустичні параметри: поздовжні (VL), поперечні (VT) швидкості та швидкість Релея (VR) — від 1139 мс⁻¹ до 285 мс⁻¹, від 87 мс⁻¹ до 143 мс⁻¹ та від 562 мс⁻¹ до 136 мс⁻¹ відповідно (при пористості від 60% до 75%)

STUDY OF EFFECT OF FILTERS AND DECOMPOSITION LEVEL IN WAVELET IMAGE COMPRESSION

In this paper, we introduce a compression algorithm using wavelet transform. The principle of wavelet transform is todecompose hierarchically the input image into a series of successively lower resolution reference images and detail imageswhich contain the information needed to be reconstructed back to the next higher resolution level .The histogram of image sub-bands provides us with information on the distribution of the coefficient values in this subimage.The sub-band images resulting from wavelet transform are not of equal significance. Some sub-bands contain moreinformation than others. The total number of available bits describing an image is however inevitably limited. Therefore, it isdesirable to allocate more bits to those sub-bands images which can be coded more accurately than others. The objective of asuch bit allocation method is to optimize the overall coder performance and minimize the quantization error. In determiningwhich wavelet filter is to be used for image compression, some of the properties considered are vanishing moments. The phasenon-linearity of the filter can cause severe degradation in the subjective quality of an image. It is related to the symmetry of thefilter coefficients. The wavelet transform is implemented using a linear-phase Biorthogonal filter with four levels ofdecomposition.For this study, we use a scalar quantization with uniform threshold quantizers. The quantization method is PCM (pulsecoded modulation) for the coefficients in all high-pass sub-bands. The coefficients of low-pass sub-bands are DPCM(Differential PCM) quantized per region