FLOW FIELD ON HELODECK OF A FRIGATE: A REVIEW

Author(s):  
B Praveen ◽  
R Vijayakumar ◽  
S N Singh ◽  
V Seshadri

The various functions desired from a frontline warship such as a frigate, corvette or a destroyer, coupled with the requirement of very high speeds and economic viability restricting the size, necessitates a very dense arrangement of weapons and sensors on the top deck and superstructure. Accordingly, Navies across the world have faced several problems with respect to functions for which a good aerodynamic design for these structures is essential. Major issues include smoke nuisance created due to impinging of the ship's exhaust gases on to the top deck leading to possible suction by engine intakes and high turbulence in the ship's air-wake leading to ship aircraft interface concerns. The flow field on the helodeck is extremely complex due to its geometry and interaction with the wake of the ship’s superstructure. A knowledge of this complexity is essential for ensuring safe helo operations on the helodeck. The problem of ship helicopter interaction has hogged the lime light in recent times, due to rising demand for design of warships for increased stealth, especially in the past two decades. Consequently, several researchers in countries with advanced Navies have invested considerable resources towards evolving both experimental and numerical solutions for the problem. However, given the military nature of the operations, open literature on the subject containing details of such research, which can be used as reference material for present work, are limited. Considering the complexities involved in the problem, an attempt has been made in this paper to holistically review the widely scattered and limited literature in this field. A good amount of literature on marine helo applications emerge from the offshore industry. Keeping in mind that the fields of warship design and offshore structures are dissimilar and have their peculiar problems, informed conclusions have been made in drawing lessons from available literature.

2019 ◽  
Vol 161 (A4) ◽  

The various functions desired from a frontline warship such as a frigate, corvette or a destroyer, coupled with the requirement of very high speeds and economic viability restricting the size, necessitates a very dense arrangement of weapons and sensors on the top deck and superstructure. Accordingly, Navies across the world have faced several problems with respect to functions for which a good aerodynamic design for these structures is essential. Major issues include smoke nuisance created due to impinging of the ship's exhaust gases on to the top deck leading to possible suction by engine intakes and high turbulence in the ship's air-wake leading to ship aircraft interface concerns. The flow field on the helodeck is extremely complex due to its geometry and interaction with the wake of the ship’s superstructure. A knowledge of this complexity is essential for ensuring safe helo operations on the helodeck. The problem of ship helicopter interaction has hogged the lime light in recent times, due to rising demand for design of warships for increased stealth, especially in the past two decades. Consequently, several researchers in countries with advanced Navies have invested considerable resources towards evolving both experimental and numerical solutions for the problem. However, given the military nature of the operations, open literature on the subject containing details of such research, which can be used as reference material for present work, are limited. Considering the complexities involved in the problem, an attempt has been made in this paper to holistically review the widely scattered and limited literature in this field. A good amount of literature on marine helo applications emerge from the offshore industry. Keeping in mind that the fields of warship design and offshore structures are dissimilar and have their peculiar problems, informed conclusions have been made in drawing lessons from available literature.


1931 ◽  
Vol 35 (245) ◽  
pp. 341-371
Author(s):  
A. Gouge

The subject I have to talk about this evening is one on which many previous papers have been read before this Society, so I am afraid I must ask you not to expect much original material from me. Practically the whole of the material I have gathered together is the result of practical experience, and from this point of view I hope it will prove interesting.During recent years considerable development has been done and good progress made with both the design and operation of big flying boats.Also, the Schneider Cup races have caused a considerable amount of research work to be done on the development of twin float seaplanes, particularly with regard to taking off the water at very high speeds and also to the air resistance of the floats.In the last year we have seen the advent of the Dornier Do.X the largest flying boat yet constructed, whose total flying weight approximates to 50 tons.


Think India ◽  
2019 ◽  
Vol 22 (3) ◽  
pp. 72-83
Author(s):  
Tushar Kadian

Actually, basic needs postulates securing of the elementary conditions of existence to every human being. Despite of the practical and theoretical importance of the subject the greatest irony is non- availability of any universal preliminary definition of the concept of basic needs. Moreover, this becomes the reason for unpredictability of various political programmes aiming at providing basic needs to the people. The shift is necessary for development of this or any other conception. No labour reforms could be made in history till labours were treated as objects. Its only after they were started being treating as subjects, labour unions were allowed to represent themselves in strategy formulations that labour reforms could become a reality. The present research paper highlights the basic needs of Human Rights in life.


2018 ◽  
Vol 11 (2) ◽  
pp. 41-51 ◽  
Author(s):  
I. Ya. Lukasevich

The subject of the research is new tools for business financing using the initial coin offering (ICO) in the context of the development of cryptocurrencies and the blockchain technologies as their basis. The purpose of the work was to analyze the advantages and disadvantages of the ICO in comparison with traditional financial tools as well as prospects, limitations and problems of using digital financial tools. Conclusions are made in relation to possibilities, limitations and application areas of digital business financing tools, particularly in the real sector, taking into account the specifics of the Russian economy and legislation. It is shown that the main problems of using the digital financial tools are related to the economic sphere and caused by the lack of adequate approaches to evaluation of assets as well as the shortage of objective information. The problems and new tasks of corporate finance in the digital economy are defined.


1983 ◽  
Vol 22 (1) ◽  
pp. 57-61
Author(s):  
Shahrukh Rafi Khan

The book under review is a compilation of the author's articles and lectures that highlight the prominent developments in the literature on the subject of Islamic banking and inform the reader of the current state of debate on it. One of the earliest and main contributors to this topic is the author himself. The focus of this review will mainly be on "Economics of Profit-Sharing", which is the title of the fourth chapter of the book and is among his latest contributions. This chapter is a significant contribution as it is the first attempt to formalise the concept of profit sharing into an analytical model and, therefore, demands closer scrutiny. However, in the remaining chapters of the book, the author has drawn attention to some of the fine points made in the literature on this topic. Since some of these points appear to be controversial to me, I will briefly discuss them before moving on to the analytical chapter of the book.


2019 ◽  
Vol 1 (34) ◽  
pp. 391-422
Author(s):  
اشواق حسن حميد صالح

Climate change and its impact on water resources is the problem of the times. Therefore, this study is concerned with the subject of climate change and its impact on the water ration of the grape harvest in Diyala Governorate. The study was based on the data of the Khanaqin climate station for the period 1973-2017, (1986-2017) due to lack of data at governorate level. The general trend of the elements of the climate and its effect on the water formula was extracted. The equation of change was extracted for the duration of the study. The statistical analysis was also used between the elements of the climate (actual brightness, normal temperature, micro and maximum degrees Celsius, wind speed m / s, relative humidity% The results of the statistical analysis confirm that the water ration for the study area is based mainly on the X7 evaporation / netting variable, which is affected by a set of independent variables X1 Solar Brightness X4 X5 Extreme Temperature Wind Speed ​​3X Minimal Temperature and Very High Level .


2020 ◽  
Vol 22 (2) ◽  
pp. 1-27
Author(s):  
João Carlos Brum Torres

O artigo tem por objeto o exame de três registros de gritantes e distintos paradoxos na Doutrina do Direito de Kant. Registros feitos em tempos e contextos históricos diferentes por Friedrich Bouterwek, Marcus Willaschek e Balthazar Barbosa Filho. Bouterwek atribuiu a Kant a mais paradoxal das proposições jamais enunciadas por qualquer autor, a de que a mera ideia de soberania deve obrigar-nos a obedecer como a nosso inquestionável senhor a quem quer que se haja estabelecido como tal, sem que caiba indagar quem lhe deu o direito de comandar-nos. Willaschek aponta a incompatibilidade de duas teses centrais da doutrina kantiana: a do caráter externo dos vínculos jurídicos e a da incondicionalidade obrigacional do direito positivo, pois não é possível entender como é possível termo-nos como obrigados por imperativos jurídicos e, ao mesmo, vermo-nos internamente isentados do dever de obedecê-los. O ponto crítico de Balthazar é alegar que não pode haver na filosofia kantiana uma crítica da razão político e jurídica, simplesmente porque o conceito de imputação, base da normatividade própria dessas esferas, pressupõe uma pluralidade de agentes livres que, justamente, só pode ser uma pressuposição, pois nosso acesso à normatividade prática só pode ter lugar em primeira pessoa. No exame a que o artigo submete essas alegações, o artigo argumenta, em objeção à tese de Balthazar, que o caráter universal e categórico da força que vincula o sujeito quando confrontado com a lei moral em primeira pessoa necessariamente se desvaneceria se, ao mesmo tempo, ele não fosse tomado pela evidência de que a realidade objetiva dos princípios morais é não só instanciável, mas assegurada pela múltipla instanciação. Com relação às dificuldades levantadas por Willaschek e Bouterwek, o artigo argumenta que o princípio exeundum e statu naturali, enquanto norma metapositiva, anterior à divisão do domínio prático entre doutrina do direito e doutrina da virtude, permite ao mesmo tempo compreender a exigência de obediência ao poder constituído e a restrição das obrigações jurídico-políticas exclusivamente ao foro externo.AbstractThe object of the article is to examine three claims about three distinct and allegedly blatant paradoxes in Kant's Doctrine of Right. These three critical points had been made in distinct times and contexts by Friedrich Bouterwek, Marcus Willaschek e Balthazar Barbosa Filho. Bouterwek attributed to Kant the most paradoxical of all paradoxical propositions, the statement that by the mere idea of sovereignty we are obliged to obey as our lord who has imposed himself upon us, without questioning from where he got such right. Willaschek points out the incompatibility of two main theses of Kantian doctrine of right: the claims that the legal bounds are of external character and that they are the source of unconditional obligations, since it seems impossible to understand how it would be possible to be obliged by juridical norms and decisions and at the same time to be exempted of the internal duty of compliance. The radical objection of Professor Balthazar is the claim that in the context of Kantian Philosophy it is impossible to admit a critique of the juridical and political reason because the concept of imputation, ground of the normativity in these domains, requires not only the presupposition of free agents, but a true and secure epistemic access to them, which is, according to him, impossible considering that the moral law and the other practical principles are accessible for us only in the first person. In the course of the appraisal of such claims, the article contest that objection arguing that the universal and categorical force of the normative bound experienced by the subject when confronted with the moral law in the first person would ineluctably vanish if, at the same time, he had not been taken by the evidence that the objective reality of the moral principles is secured by multiple instancing. Regarding the difficulties raised by Willaschek and Bouterwek, the article argues that the principle exeundum e statu naturali, as a norm of meta-positive character, prior to the division of practical domains between the doctrine of right and the doctrine of virtue, is the cue both to the understanding of the requirement of unquestioning obedience to the constituted power and to the restriction of the validity of this requirement only in foro externo.


2000 ◽  
Vol 41 (4-5) ◽  
pp. 253-260 ◽  
Author(s):  
P. Buffière ◽  
R. Moletta

An anaerobic inverse turbulent bed, in which the biogas only ensures fluidisation of floating carrier particles, was investigated for carbon removal kinetics and for biofilm growth and detachment. The range of operation of the reactor was kept within 5 and 30 kgCOD· m−3· d−1, with Hydraulic Retention Times between 0.28 and 1 day. The carbon removal efficiency remained between 70 and 85%. Biofilm size were rather low (between 5 and 30 μm) while biofilm density reached very high values (over 80 kgVS· m−3). The biofilm size and density varied with increasing carbon removal rates with opposite trends; as biofilm size increases, its density decreases. On the one hand, biomass activity within the reactor was kept at a high level, (between 0.23 and 0.75 kgTOC· kgVS· d−1, i.e. between 0.6 and 1.85 kgCOD·kgVS · d−1).This result indicates that high turbulence and shear may favour growth of thin, dense and active biofilms. It is thus an interesting tool for biomass control. On the other hand, volatile solid detachment increases quasi linearly with carbon removal rate and the total amount of solid in the reactor levels off at high OLR. This means that detachment could be a limit of the process at higher organic loading rates.


Author(s):  
Steven J. R. Ellis

This chapter examines the socio-economic motivations behind the shaping of retail landscapes in Roman cities. It is about who opened retail outlets, as well as why and where. After critiquing some of the normal methods for illustrating the locations of shops and bars, including the conventional distribution plan itself, as well as questioning the economic rationality of operating tabernae, this chapter argues for the value in complicating our otherwise basic understanding of why urban investments were made in the places we find them. Rather than accepting profit as the single motivation to urban investment, a range of social, economic, and political motivations are considered as an explanation for the ultimate shape of Roman retail landscapes. Thus beyond discussions of space and urban topography, the subject of this chapter is investment.


Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4901
Author(s):  
Lucjan Setlak ◽  
Rafał Kowalik

Sometimes, it is impossible to conduct tests with the use of the GNSS system, or the obtained results of the measurements made differ significantly from the predicted accuracy. The most common cause of the problems (external factors, faulty results) are interference disturbances from other radio telecommunication systems. The subject of this paper is to conduct research, the essence of which is an in-depth analysis in the field of elimination of LTE interference signals of the GNSS receiver, that is based on the developed effective methods on counteracting the phenomenon of interference signals coming from this system and transmitted on the same frequency. Interference signals are signals transmitted in the GNSS operating band, and unwanted signals may cause incorrect processing of the information provided to the end-user about his position, speed, and current time. This article presents methods of identifying and detecting interference signals, with particular emphasis on methods based on spatial processing of signals transmitted by the LTE system. A comparative analysis of the methods of detecting an unwanted signal was made in terms of their effectiveness and complexity of their implementation. Moreover, the concept of a new comprehensive anti-interference solution was proposed. It includes, among others, information on the various stages of GNSS signal processing in the proposed system, in relation to the algorithms used in traditional GNSS receivers. The final part of the article presents the obtained research results and the resulting significant observations and practical conclusions.


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