Nonhomogeneous multicolor laser beams optimization to obtain a stronger intensity single harmonic radiation path

How to obtain the high signal intensity harmonic spectra with the single harmonic radiation path contribution becomes an important issue in the investigations of the high-order harmonic generation and attosecond science. In this paper, through the nonhomogeneous multicolor laser beams optimization, the best time-spatial laser waveforms, including the positive and negative time-spatial waveforms, to produce the harmonic spectra can be found. As a result, the harmonic plateaus with the single harmonic radiation path contribution and with the enhancement of several orders of magnitudes can be obtained, which can support the generation of the isolated pulses with the durations of 29 as. The physical mechanism behind the improvement of the harmonic spectra is given by the time-spatial profile analyses of the laser pulses and the harmonic spectra.

CPW-Fed Transparent Antenna for Vehicle Communications

In this paper, a fully transparent multiband antenna for vehicle communications is designed, fabricated, and analyzed. The antenna is coplanar waveguide-fed to facilitate its manufacture and increase its transmittance. An indium-tin-oxide film, a type of transparent conducting oxide, is selected as the conductive material for the radiation path and ground plane, with 8 ohms/square sheet resistance. The substrate is glass with a relative permittivity of 5.5, and the overall dimensions of the optimized design are 50 mm × 17 mm × 1.1 mm. The main antenna parameters, namely, sheet resistance, reflection coefficient, and radiation diagram, were measured and compared with simulations. The proposed antenna fulfills the frequency requirements for vehicular communications according to the IEEE 802.11p standard. Additionally, it covers the frequency bands from 1.82 to 2.5 GHz for possible LTE communications applied to vehicular networks.

ОСОБЕННОСТИ ПРИМЕНЕНИЯ АВТОНОМНОГО НЕОБИТАЕМОГО ПОДВОДНОГО АППАРАТА ПРИ ИЗУЧЕНИИ ПРОСТРАНСТВЕННОЙ СТРУКТУРЫ ГИДРОАКУСТИЧЕСКИХ ПОЛЕЙ

В работе описывается эксперимент, проведенный с участием автономного необитаемого подводного аппарата (АНПА), оснащенного высокоточной гидроакустической измерительной аппаратурой, низкочастотным гидроакустическим излучателем, а так же береговыми лазерными деформографами. Целью данного эксперимента являлось изучение пространственновременного распределения поля давления, создаваемого низкочастотным гидроакустическим излучателем на шельфе клиновидной формы, а также выявление закономерностей трансформации гидроакустической энергии в сейсмическую. В ходе анализа и обработки полученных экспериментальных данных, была построена общая картина пространственного распределения поля гидроакустического давления на шельфе убывающей глубины, разработаны алгоритмы построения вертикальных разрезов поля давления по глубине на произвольном расстоянии от излучателя, по которым, в свою очередь можно вычислять горизонтальное распределение гидроакустической энергии на всем протяжении трассы излучения. По вертикальным распределениям давления, в представленной работе, были сделаны некоторые заключения о взаимодействии гидроакустического сигнала с дном и трансформации его в сейсмоакустический сигнал. Представлены результаты расчетов горизонтального распределения энергии и их сравнения с теоретически рассчитанными данными. Ключевые слова: гидроакустический излучатель, автономный необитаемый подводный аппарат, деформограф, пространственное распределение поля давления, шельф, трансформация гидроакустической энергии.The paper describes an experiment conducted with the participation an autonomous uninhabited underwater vehicle (AUV) was equipped with highprecision hydroacoustic measuring equipment, a lowfrequency hydroacoustic radiator, and coastal laser strainmeters. The aims of this experiment was to study the spatiotemporal distribution of the pressure field, created by a lowfrequency radiator on a wedgeshaped shelf, as well as to identify patterns of transformation of hydroacoustic energy into seismic. During the analysis and processing of the obtained experimental data, a general picture of the spatial distribution of the field of hydroacoustic pressure on the shelf of decreasing depth was gained, algorithms for constructing vertical layer of the pressure field by depth at an arbitrary distance from the radiator were developed, from which, in turn, it is possible to calculate the horizontal distribution of hydroacoustic energy all along the radiation path. By the vertical pressure distributions, in the present work, some conclusions were inferred about the interaction of the hydroacoustic signal with the bottom and its transformation into a seismic signal. The results of calculations of the horizontal energy distribution and their comparison with theoretically calculated data are presented. Keywords: hydroacoustic radiator, autonomous uninhabited underwater vehicle, strainmeter, spatial distribution of the pressure field, shelf, transformation of hydroacoustic energy.

ОСОБЕННОСТИ ПРИМЕНЕНИЯ АВТОНОМНОГО НЕОБИТАЕМОГО ПОДВОДНОГО АППАРАТА ПРИ ИЗУЧЕНИИ ПРОСТРАНСТВЕННОЙ СТРУКТУРЫ ГИДРОАКУСТИЧЕСКИХ ПОЛЕЙ

В работе описывается эксперимент, проведенный с участием автономного необитаемого подводного аппарата (АНПА), оснащенного высокоточной гидроакустической измерительной аппаратурой, низкочастотным гидроакустическим излучателем, а также береговыми лазерными деформографами. Целью данного эксперимента являлось изучение пространственновременного распределения поля давления, создаваемого низкочастотным гидроакустическим излучателем на шельфе клиновидной формы, а также выявление закономерностей трансформации гидроакустической энергии в сейсмическую. В ходе анализа и обработки полученных экспериментальных данных, была построена общая картина пространственного распределения поля гидроакустического давления на шельфе убывающей глубины, разработаны алгоритмы построения вертикальных разрезов поля давления по глубине на произвольном расстоянии от излучателя, по которым, в свою очередь можно вычислять горизонтальное распределение гидроакустической энергии на всем протяжении трассы излучения. По вертикальным распределениям давления, в представленной работе, были сделаны некоторые заключения о взаимодействии гидроакустического сигнала с дном и трансформации его в сейсмоакустический сигнал. Представлены результаты расчетов горизонтального распределения энергии и их сравнения с теоретически рассчитанными данными.The paper describes an experiment conducted with the participation an autonomous uninhabited underwater vehicle (AUV) was equipped with highprecision hydroacoustic measuring equipment, a lowfrequency hydroacoustic radiator, and coastal laser strainmeters. The aims of this experiment was to study the spatiotemporal distribution of the pressure field, created by a lowfrequency radiator on a wedgeshaped shelf, as well as to identify patterns of transformation of hydroacoustic energy into seismic. During the analysis and processing of the obtained experimental data, a general picture of the spatial distribution of the field of hydroacoustic pressure on the shelf of decreasing depth was gained, algorithms for constructing vertical layer of the pressure field by depth at an arbitrary distance from the radiator were developed, from which, in turn, it is possible to calculate the horizontal distribution of hydroacoustic energy all along the radiation path. By the vertical pressure distributions, in the present work, some conclusions were inferred about the interaction of the hydroacoustic signal with the bottom and its transformation into a seismic signal. The results of calculations of the horizontal energy distribution and their comparison with theoretically calculated data are presented.

Personal UV exposure on a ski-field at an alpine site

Mountain sites experience enhanced ambient UV radiation levels due to the concurrent effects of shorter radiation path-length, low aerosol load and high reflectivity of the snow surfaces. This study was encouraged by the possibility to collect data of personal UV exposure in the mountainous areas of Italy, for the first time. Personal UV exposure (expressed in terms of Exposure Ratio, ER) of two groups of volunteers (ski instructors and skiers) at the Alpine site of La Thuile (Valle d'Aosta region, Italy) was assessed using polysulphone dosimetry which was tested in a mountainous snow-covered environment. In addition measurements of biological markers of individual response to UV exposure such as skin colorimetric parameters were carried out. It was found that snow and altitude of study site affect calibration curves of polysulphone dosimeters in comparison to a situation without snow. The median ER, taking into account the whole sample, is 0.60 in winter, with a range of 0.29 to 1.46, and 1.02 in spring, ranging from 0.46 to 1.72. There are no differences in exposures across skiers and instructors in spring while in winter skiers experience lower values. UV exposures are not sensitive to the use of sunscreen across instructor/skier group by day or by seasons or by photo-type. With regard to colorimetric parameters, the main result was that both skiers and instructors had on average significantly lower values of L* and b* after exposure i.e. becoming darker but the inappropriate sunscreen use did not reveal any changes in skin colorimetric parameters except in one spring day. In conclusions UV intensities on the ski-fields are often significantly higher than those on horizontal surfaces. Given the high levels of exposure observed in the present study, dedicated public heath messages on the correct sunscreen use should be adopted.

A New Approach to Spatially Resolved Flame Temperature Measurements

Spatially resolved flame temperatures are spectroscopically measured using the slope method, over small (≃0.7 μl), relatively homogenous volumes of flame gases. The spatial resolution is uniquely obtained by introducing Co as a thermometric species into isolated volumes via the use of a droplet injection technique. By this method the emission of light is restricted to a limited volume, whose position in the flame can be accurately determined and controlled. Vertical resolution is determined by the width of the entrance slit of the monochromator employed (100 μm in this study), and horizontal resolution is limited by the width of the emission cloud formed by the injected droplets (1 to 3 mm). The possibility of self-absorption effects are greatly reduced because of the short radiation path length involved. The performance of the method is illustrated by its application to the spatial temperature mapping of the secondary reaction zone of a cylindrical air-acetylene flame. The effects of N2 as a sheathing gas and flame stoichiometry on the radial and vertical temperature distribution of the flame are also investigated. It is determined that a large, virtually isothermal, central zone exists in the flame.