Generating new solutions for relativistic transverse flow at the softest point

Using the method of prolongation we generate new solutions from a simple particular solution for relativistic transverse flow with cylindrical symmetry in 1+3 dimensions. This is an extension of the longitudinal Bjorken flow ansatz and can be applied among others during first order phase transition in an expanding system. The prolongated solution allows for tracing back the flow profile from a transverse flow conjectured at the end of phase transition at CERN SPS heavy ion collisons.Comment: 11 pages LaTeX, 1 ps figur

Analytic solution for relativistic transverse flow at the softest point

We obtain an extension of Bjorken's 1+1 dimensional scaling relativistic flow solution to relativistic transverse velocities with cylindrical symmetry in 1+3 dimensions at constant, homogeneous pressure (vanishing sound velocity). This can be the situation during a first order phase transition converting quark matter into hadron matter in relativistic heavy ion collisions.Comment: 9 pages LaTeX, 1 .eps figure, Figure replaced by another presentation showing contour-lines of QGP-hadron phase mixtures in the longitudinal time - transverse radius plane. To appear in Phys.Lett.

Theoretical and Experimental Study of Piezoelectric Modulated AlN Thin Films for Shear Mode BAW Resonators

The use of acoustic resonators for sensors application has opened a new branch in research and applications of piezoelectric materials and devices. The first generation of such sensors is constituted by the quartz crystal microbalance (QCM) based on AT-cut mono-crystalline quartz. High sensitivities of gravimetric sensing in both air and liquids were demonstrated. Since the 1980s, when the first QCM-based sensor was demonstrated for the detection of silver in a liquid solution, many other application in chemical, bio-medical and environmental sensing were realized using the same concept. QCM's exhibit a very good thermal stability. The AT-cut quartz plate leads to the excitation of shear waves when used in parallel capacitor geometry. This is important for achieving high quality factors in the immersed operation of the sensor. A second generation of gravimetric sensors is based on surface acoustic wave (SAW) structures, working for instance with Love waves in a SiO2 layer on top of a LiTaO3 single crystal. SAW devices are mainly used as RF filters in television and mobile phones. SAW sensors are a side product of the much larger telecommunication market. The evolution of thin film and MEMS technology has lead to a third generation of gravimetric sensors that is based on bulk acoustic wave (BAW) resonances in piezoelectric thin films. Again, such sensors are a side product from the large telecommunication market where such resonators are used for RF filters. With every generation, the oscillation frequency increased. While QCM's operate typically at 5 MHz, the SAW resonators work typically at a few 100 MHz, and the thin film BAW resonators (TFBAR) operate typically around 2 GHz. The increase of the frequency goes together with an increase in sensitivity, and a decrease of the thickness and mass range that can be measured. The TFBARs are in some sense miniaturized analogs of QCM's operating at much higher frequencies. They are very promising as they reach higher sensitivities. This attracted the attention of researchers, and experimental evidence of the potential of TFBARs as sensors was delivered. In addition to the higher sensitivity, the miniaturization allows for using arrays of sensors with different immobilization layers as needed for drug screening. However, the application of the same TFBARs as used in telecommunications would not allow a good performance in immersed operation. It would only be good for operation in air. The principal characteristic of TFBARs used in mobile phones is the value of the electromechanical coupling and not the resonance mode at which this coupling is achieved. But for the in-liquid operated sensors, it's rather the opposite – the mode of the resonance should be such that the surface of the resonator, which tis in contact with liquid, should move parallel to the surface (in-plane motion, or transverse motion) to minimize emission of acoustic waves into the liquid. The coupling coefficient is of secondary importance in this case. Therefore, the development of shear mode TFBARs became an interesting task that was challenged by several research groups. One of the most successful solutions is the use of c-axis inclined AlN thin films. Inclination of c-axis in a parallel plate capacitor structure enables the coupling of the electric field to the shear strain, which enables the excitation of a shear mode. Such devices were successfully applied for selective sensing of organic species, such as DNA molecules, suspended in a liquid. Even if the process of deposition of c-axis inclined AlN films doesn't require hardware modification, the quality of the process is still far from the one for deposition of (0001)AlN films used in telecommunications. So the goal of this thesis was to find a solution for the shear mode TFBAR's based on (0001)AlN films. In (0001)AlN films, the shear strain cannot be induced by the electric field produced in a parallel plate geometry as the coefficient e35 and e34 of the piezoelectric tensor are zero. But there are e15 and e24 coefficients that are not zero, meaning that in-plane electric field can be used to excite the shear waves. In the frame of this work, this concept was studied theoretically and experimentally. The in-plane electric field was generated via inter-digitated electrodes (IDE). A first device type was realized in solidly mounted resonator (SMR) design and based on uniform (0001)- oriented AlN thin films. The anti-phase of the electric field in adjacent half-periods of the IDE resulted in an anti-phase movement of the corresponding regions of the film. Finite element modeling and boundary element modeling (FEM-BEM) were carried out to clarify the kind of vibrations present in the device. A kind of shear/lingitudinal mode with elliptic motions was obtained. A device was fabricated and tested both in liquid and air. The resonance of the device was observed in the expected frequency range (1.86 GHz) and high quality factors under operations in air (Q=870) and silicon oil (Q=270) were obtained. The drop of the quality factor was explained by the up and down motion of the regions of the film located directly under the IDE electrodes. Such a motion is due to anti-phase motion of different regions of the film as mentioned above. To prevent this effect, a second device type was studied. It is again based on the use of (0001)AlN thin films, but with modulated piezoelectric properties. Having different piezoelectric properties in the regions corresponding to adjacent half-periods of IDE, breaks the mirror symmetry of the device and allows for coupling the electric field to a pure shear mode. Analytical and numerical models explaining such a device were established and evaluated. The optimal situation is found when perfect Al-polar and N-polar regions of AlN are combined. This maximizes the coupling coefficient k that is derived as being proportional to the difference of e15 coefficients. Finding a way to fabricate the AlN thin film with different piezoelectric properties was thus the next objective. Growth features to decrease the piezoelectric effect were first studied. Providing rougher regions on the otherwise smooth substrate allowed to modify locally the quality of AlN thin films. Device based on such films were fabricated and characterized. The resonance of a pure shear mode was found at the expected frequency (roughly 2GHz) when the piezoelectric effect was modulated. Devices without this modulation failed to show the resonance at the exact frequency, exactly as the theory predicted. We managed to reduce two times the d33 coefficient of the film by inducing a increased roughness to the substrate – from 5.0 pm/V, corresponding to 1.5 degree rocking curve, down to 2.4pm/V, corresponding to 7 degree of rocking curve. The final step of the thesis was the process development for the simultaneous growth of Al-polar and N-polar regions within sputter deposited (0001)AlN, in order to achieve the maximal possible "piezomodulation" effect. As the sputter deposition yielded only N-polar films, we included Al-polar films from another source as seed layers. High temperature epitaxial growth methods of GaN and AlN on Si(111) and Si(100) lead to Ga- and Al-polarities. On such films, the sputter deposited AlN copies polarity from the growth substrate. The selective polarity was then obtained by preventing the expitaxy locally through a patterned oxide layer. Wet etching tests together with PFM measurements were performed to prove the dual polarity in the sputter deposited film. Finally, the integration of this process into the process flow for device fabrication was investigated

Thermal description of transverse-momentum spectra at RHIC

We show that the transverse-momentum spectra of all hadrons measured at RHIC, including hyperons, are described very well in a thermal model assuming the simultaneous chemical and thermal freeze-outs. The model calculation takes into account all hadronic resonances and uses a simple parametrization of the freeze-out hypersurface.Comment: contribution to QM02 Conference, 4 page

Thermal analysis of production of resonances in relativistic heavy-ion collisions

Production of resonances is considered in the framework of the single-freeze-out model of ultra-relativistic heavy ion collisions. The formalism involves the virial expansion, where the probability to form a resonance in a two-body channel is proportional to the derivative of the phase-shift with respect to the invariant mass. The thermal model incorporates longitudinal and transverse flow, as well as kinematic cuts of the STAR experiment at RHIC. We find that the shape of the pi+ pi- spectral line qualitatively reproduces the preliminary experimental data when the position of the rho peak is lowered. This confirms the need to include the medium effects in the description of the RHIC data. We also analyze the transverse-momentum spectra of rho, K*(892), and f_0(980), and find that the slopes agree with the observed values. Predictions are made for eta, eta', omega, phi, Lambda(1520), and Sigma(1385).Comment: minor modifications, a reference adde

Approaches to rehabilitation of radioactive contaminated territories

BACKGROUND: Accidents at nuclear fuel cycle plants may lead to contamination of areas of land and water. Cheap and available sorbents including natural aluminosilicates can be used for rehabilitation and decontamination of large volumes of radioactively contaminated water, including drinking water, prevention of migration of radionuclides into ground and surface waters through the soil and returning contaminated soil to farming. RESULTS AND DISCUSSION: A comparative study of sorption properties of various natural and surface-modified aluminosilicates with respect to caesium is made. It is shown that sorption features of surface-modified aluminosilicates for Cs were improved by 100-1000 times compared with respective natural aluminosilicates. It is shown that surface modification of glauconite by a mixed nickel-potassium ferrocyanide phase allows it to considerably increase its specificity (caesium distribution coefficients (2.9 ± 0.8)Ч103 mL g-1 for natural and (4.5 ± 0.5)Ч105 mL g-1 for modified glauconite) as well as making it selective to caesium in the presence of other alkaline ions and also provides irreversible caesium sorption. CONCLUSIONS: Due to improved features, modified aluminosilicates can be more successful than natural ones when used for rehabilitation of radioactive contaminated territories (including agriculture) and water areas, as well as for decontamination of liquid radioactive wastes and for creation of geochemical barriers in solid radioactive waste storage. © 2013 Society of Chemical Industry

Переносні засоби димо- та тепловидалення для підвищення ефективності гасіння пожеж підрозділами ОРС ЦЗ ДСНС України

One of the priority tactical methods for reducing the effect of high temperatures and smoke on the personnel of the fire and rescue units is to control the heat drift flux of fire with the help of fire smoke exhausters, which are functionally designed for local increase of air pressure by injecting clean air into the work area of ​​the staff or removing combustion products from premises in the conditions of fire for the normalization of temperature and air environment in order to ensure safe conditions during rescue operations. The analysis of the rescue operation of the rescue services of the world leading countries indicates the considerable tactical significance of the use of portable fire extinguishers. Modern fire extinguishers, which are used by the rescue services of the leading countries of the world nowadays, are more maneuverable due to their installation on wheels, the dimensions are more compact and there is the possibility of their assembly, the capacity for fresh air is up to 60000–70000 m3 / h. In the fire and rescue subdivisions of the SSU of Ukraine, fire extinguishers are practically not used. In order to assist in solving this problem, Ukrainian Civil Protection Research Institute began the implementation of research work, the purpose of which is to substantiate the technical requirements for modern portable fire extinguishers and to develop proposals for improving the efficiency of fire extinguishing with their use. To achieve the goal in the framework of this study, the authors plan to solve the following tasks: to conduct an analysis of information on the availability and use of portable fire extinguishers by the fire and rescue units of the leading countries of the world; to carry out the analysis of the normative and technical documentation, in particular to study the technical requirements for portable fire extinguishers from the leading countries of the world; to conduct a patent search on the given issue; to conduct mathematical calculation of technical parameters for the creation of a functional model of portable fire extinguisher; to substantiate and develop technical requirements for portable fire smoke exhausters; to create a functional model of portable fire extinguisher; to develop a methodology for conducting experimental studies of this functional model and carry out experimental research. The implementation of the research will be carried out by sending recommendations on the practical application of portable means of smoke and heat dissipation to the departments of DSNS of Ukraine.Розглянуто актуальність питання застосування підрозділами ОРСЦЗ ДСНС України переносних засобів димо- та тепловидалення (пожежних димососів). Встановлено, що нагнітання свіжого повітря у приміщення є найефективнішим порівняно з відсмоктуванням загазованого повітря. Зазначено, що застосування комбінованого способу управління газовими потоками за допомогою пожежних димососів дає змогу знизити температурний вплив на людину на основних шляхах евакуації. З'ясовано фактори, що підвищують ефективність гасіння пожеж із застосуванням пожежних димососів. Наведено основні ознаки, за якими класифікують пожежні димососи. Встановлено основні критерії для вирішення питання компоновки переносного засобу димо- та тепловидалення (пожежного димососу). Оптимальні параметри за масою, габаритні розміри та характеристики двигуна буде визначено за результатами аналізу зарубіжних розробок у цій галузі. Наведено порівняння основних технічних характеристик пожежних димососів часів Радянського Союзу із відповідними сучасними зразками, які застосовують у провідних країнах світу. Зазначено потреба виконання науково-дослідної роботи, щоб обґрунтувати технічні вимоги до сучасних переносних пожежних димососів і розробити пропозиції з підвищення ефективності гасіння пожеж з їх застосуванням. Визначено основні завдання, які необхідно вирішити в рамках виконання науково-дослідної роботи

Оптимизация технологии получения комбинированных целлюлозно-неорганических сорбентов для концентрирования радиоактивного цезия

Статтю присвячено оптимізації умов синтезу селективних до радіоактивного цезію комбінованих поглинальних матеріалів на основі целюлозного волокна і фероціаніду міді. Досліджено вплив параметрів модифікування волокна на вміст модифікатора в об’ємі органічного носія і на сорбційні характеристики продуктів. За результатами математичної обробки отриманих експериментальних даних одержано адекватні статистичні моделі процесу модифікування вибіленого бавовняного волокна розчинами фероціаніду міді за різних значень рН середовища та температури процесу. Визначено оптимальні значення технологічних параметрів процесу з використанням функції бажаності Харрінгтона. Показано, що оптимальними параметрами процесу модифікування, що забезпечують одержання ефективних сорбентів з вмістом фероціаніду міді в об’ємі носія 4,37 %, які характеризуються ступенем вилучення цезію з водних розчинів 95,14 % та коефіцієнтом розподілення 7501 мл/г, є рН середовища 5,4 та температура 90 °С. Однак оптимальні питомі сорбційні властивості сорбентів (питомі ступінь вилучення цезію 35,76 %/г та коефіцієнт розподілення 2236 (мл/г)/г) досягаються при вмісті модифікатора в сорбенті 2,71 %, який одержують при рН 7,8 та температурі 90 °С.In this article the optimization of the synthesis conditions of combined sorption materials based on cellulose fiber and copper ferrocyanide selective toward radioactive cesium. The influence of the parameters of modification process on the modifier in the bulk of organic carrier content and sorption characteristics of products was investigated. According to the results of mathematical processing of the experimental data the adequate statistical model of the modification of bleached cotton fiber with the solutions of copper ferrocyanide at different values of pH and temperature of the process were obtained. The optimal values of the technological parameters were determined using Harrington's desirability function. It was shown that the optimum parameters of the modification process allowing to obtain an effective sorbents with the content of copper ferrocyanide 4.37 % in the volume of the carrier, which are characterized by a recovery rate of cesium from aqueous solutions of 95.14 % and the distribution coefficient of 7501 ml/g, are pH 5.4 and temperature 90 °C. However, the optimal specific sorption properties (specific recovery rate of cesium 35.76 %/g and a distribution coefficient 2236 (ml/g)/g) is achieved when the modifier content is 2.71 % in a sorbent which is prepared at pH 7.8 and 90 °C.Статья посвящена оптимизированию условий синтеза селективных к радиоактивному цезию комбинированных поглощающих материалов на основе целлюлозного волокна и ферроцианида меди. Исследовано влияние параметров модифицирования волокна на содержание модификатора в объеме органического носителя и на сорбционные характеристики продуктов. По результатам математической обработки экспериментальных данных получены адекватные статистические модели процесса модифицирования беленого хлопкового волокна растворами ферроцианида меди при разных значениях рН среды и температуры процесса. Определены оптимальные значения технологических параметров процесса с использованием функции желательности Харрингтона. Показано, что оптимальными параметрами процесса модифицирования, обеспечивающими получение эффективных сорбентов с содержанием ферроцианида меди в объеме носителя 4,37 %, которые характеризуются степенью извлечения цезия из водных растворов 95,14 % и коэффициентом распределения 7501 мл/г, является рН среды 5,4 и температура 90 °С. Однако оптимальные удельные сорбционные свойства материалов (удельные степень извлечения цезия 35,76 %/г и коэффициент распределения 2236 (мл/г)/г) достигаются при содержании модификатора в сорбенте 2,71 %, который получают при рН 7,8 и температуре 90 °С

Strange particle production at RHIC in a single-freeze-out model

Strange particle ratios and pT-spectra are calculated in a thermal model with single freeze-out, previously used successfully to describe non-strange particle production at RHIC. The model and the recently released data for phi, Lambda, anti-Lambda, and K*(892) are in very satisfactory agreement, showing that the thermal approach can be used to describe the strangeness production at RHIC.Comment: We have added the comparison of the model predictions to the newly released Lambda and K*(892) pT-spectra from STA