DEPENDENCE OF VIVALDI ANTENNA CHARACTERISTICS ON THE SUBSTRATE METALLIZATION

Рассматривается антенна Вивальди, рабочий диапазон которой соответствует частотам, выделенным Государственной комиссией по радиочастотам для сетей пятого поколения. Применение различных проводниковых материалов при изготовлении излучателя позволяет достичь как экономических преимуществ, так и требуемых характеристик диаграмм направленности. В процессе моделирования были определены обратные потери антенны, а также влияние на них материала изготовления проводящей части антенны, диаграммы направленности, коэффициента полезного действия. Все характеристики определялись путем электродинамического моделирования. Исследование производилось для таких проводящих материалов, как медь, алюминий, золото, серебро, железо, платина, тантал, молибден. По полученным результатам было определено, что наилучшим проводником является серебро, при этом медь и алюминий не сильно уступают ему по характеристикам излучения и эффективности. Наихудшими материалами изготовления проводниковой части антенны являются тантал, железо и платина, так при их применении происходит снижение коэффициента полезного действия антенны, реального коэффициента усиления антенны. В статье представлены графики S-параметров для исследуемых случаев, произведено их сравнение, а также приведены основные характеристики диаграмм направленности и определено влияние на них проводниковых материалов The article considers a Vivaldi antenna, the operating range of which corresponds to the frequencies allocated by the State Commission on Radio Frequencies for fifth generation networks. The use of various conductive materials in the manufacture of the emitter allows one to achieve both economic advantages and the required characteristics of radiation patterns. In the process of modeling, we determined the return losses of the antenna, as well as the influence on them of the material of the conductive part of the antenna, the radiation pattern, and the efficiency. We determined all characteristics by electrodynamic modeling. The study was carried out for conductive materials such as copper, aluminum, gold, silver, iron, platinum, tantalum, molybdenum. Based on the results obtained, we determined that the best conductor is silver, while copper and aluminum are not much inferior to it in terms of radiation and efficiency. The worst materials for the manufacture of the conductive part of the antenna are tantalum, iron and platinum, so when they are used, the efficiency of the antenna, the real gain of the antenna, decreases. The article presents graphs of S-parameters for the cases under study, compares them, and also presents the main characteristics of the directional patterns and determines the effect of conductive material on them

Industry 4.0 and the Future of Reservoir Exploration and Characterization

The oil and gas sector seeks to adapt to changes in industry 4.0. Advances in computational processing and artificial intelligence have allowed machines to perform increasingly complex activities. However, the application of these advances to the activities of the oil industry still involves much speculation. While some areas show clear gains with the implementation of machine learning, the exploration and characterization of reservoirs still represent a challenge concerning this topic. As the primary information acquired in reservoirs, such as rock and fluid samples, well logs, and seismic data, presents a wide range of scales, the real gain from machine learning techniques would likely be integrating different databases in different scales. Such integration would improve geological and production models. The spread of information in these databases would also have the potential to decrease exploratory success. The joint efforts of oil and gas companies and research and education institutions will be essential to increase the oil and gas industry.

Adaptive Algorithm for Solar Tracking in Photovoltaic Power Plants

The diversity of the energy matrix in the world is one of the challenges demanding fornew researches with alternative energy sources to bring exibility and sustainability in their use.According with this panorama, the generation of electric energy with solar photovoltaic systemsemerges as an important goal, and its technology is constantly advancing as an immediatesolution for this quest of diversity. This paper presents a predictive control for a solar trackingalgorithm to be used in single or double axis photovoltaic systems. The main characteristicand contribution of this algorithm represents a functional technological innovation because itdoes not use any sensors to determine the position of the Sun with respect to the panel. Suchalgorithm avoids unnecessary movements in cases of shadows on the panels caused by clouds,or some animal that could interfere on systems using the conventional sensors. The proposedsolar time algorithm was tested and compared with eld values, predicting the correct Sunposition with accuracy of less than 1o. The qualitative and quantitative results presented hereevidenced the real gain of the proposed algorithm-based system without any sensors to increasethe generation gain of photovoltaic power plants.

Multiplying embryos: experimental monozygotic polyembryony in mammals and its uses

Monozygotic (MZ) polyembryony is a strategy to increase the output of a single zygote, thereby producing more offspring from a limited number of oocytes. However, MZ twins and multiples (multiplets) of mammals occur rarely in nature, while their generation has been more successful experimentally. In this work, we review some of the methodological, biological and field aspects of experimental MZ polyembryony in mammals. First attempts of mechanical bisection of 2-cell stage rodent embryos provided a proof-of-principle for the survival and independent development of both blastomeres. Subsequently, experiments in other species, particularly sheep and bovine, allowed 2 methods of embryo multiplication to become routine: the separation or biopsy of blastomeres from cleavage-stage embryos and the bisection of morulae and blastocysts. We discuss how the preferable stage of bisection and the success rate can be species-specific. The scope that profited most from experimental MZ polyembryony is the production of additional copies of elite livestock individuals, the reduction of interindividual variation in test groups and the possibility of investigating discordant phenotypic traits in the same genomic background, for instance, comparing an affected twin with its healthy co-twin. By contrast, the original motivation for experimental polyembryony – efficiently generating more offspring out of the same zygote – has not been fulfilled yet. Although embryo splitting leads to an increase in quantity, there is a loss of embryo quality, thus, there is no real gain from artificially generated embryos (yet) in the field of medically assisted reproduction. In conclusion, mammalian zygotes have the regulative capacity to be polyembryonic, but this is not obligate.

Seismic signals hard clipping overcoming

In signal processing the clipping is understand as the phenomenon of limiting the signal beyond certain threshold. It is often related to overloading of a sensor. Two particular types of clipping are being recognized: soft and hard. Beyond the limiting value soft clipping reduces the signal real gain while the hard clipping stiffly sets the signal values at the limit. In both cases certain amount of signal information is lost. Obviously if one possess the model which describes the considered signal and the threshold value (which might be slightly more difficult to obtain in the soft clipping case), the attempt of restoring the signal can be made. Commonly it is assumed that the seismic signals take form of an impulse response of some specific system. This may lead to belief that the sine wave may be the most appropriate to fit in the clipping period. However, this should be tested. In this paper the possibility of overcoming the hard clipping in seismic signals originating from a geoseismic station belonging to an underground mine is considered. A set of raw signals will be hard-clipped manually and then couple different functions will be fitted and compared in terms of least squares. The results will be then analysed.

Effect of adoption of relational contracting practices on relationship quality in public projects in Singapore

Purpose – The purpose of this paper is to investigate relational contracting (RC) practices that give rise to higher quality interpersonal relations between these pairs of stakeholders at the end of public projects: clients and contractors; contractors and consultants; and clients and consultants. It developed models to predict the level of quality of interpersonal relations between the stakeholders at the completion of public projects. Design/methodology/approach – Using a set of questionnaire, data were collected from randomly selected construction industry practitioners who have had experience in public projects in Singapore. The data were analysed to identify association between the use of RC practices and quality of interpersonal relations between stakeholders. In-depth interviews with experts were conducted. Findings – It was found that when certain RC practices were adopted to a larger extent, public projects also have significantly higher quality of interpersonal relations between clients, contractors and consultants. Three mathematical models were developed to predict the relationship quality between stakeholders at the end of the public project. Research limitations/implications – The limitations include the subjective nature of the Likert scale that was used in answering the questionnaire survey and the limited number of interviews. The effect of existing good relations among stakeholders was not taken into account. Practical implications – Suitable RC practices for adoption by public clients, contractors and consultants in public projects are recommended. These include developing deeper mutual trust and understanding, sharing project information, and having real gain-share/pain-share among contracting parties. Originality/value – RC practices that are significantly associated with relationships among contracting parties in public projects in Singapore are uncovered. Contracting parties may use the recommendations to help enhance their relationships with one another in a public project.

Some Benefits Of Reducing Inflation In South Africa

This paper evaluates the welfare gain from permanently reducing inflation from two percent to price stability and compares it the output cost associated with this transition. The paper emphasizes the distortions caused by the interaction of inflation and capital income taxation in calculating the gain from moving to a zero rate of inflation. Though the annual deadweight loss of a two percent inflation rate is 0.225 percent of GDP - a relatively small number when compared to the literature, since the real gain from shifting to price stability grows in perpetuity at the rate of growth of GDP, the present value is a substantial multiple of the annual welfare gain. Calculations reveal a present value gain of 15 percent of GDP. Since the corresponding one-off output cost of moving from two percent inflation to price stability is 0.034 percent of GDP, the gain outweighs the cost by an overwhelming margin.