Transonic accretion and winds around Pseudo-Kerr black holes andcomparison with general relativistic solutions

Spectral and timing properties of accretion flows on a black hole depend on their density and temperature distributions, which, in turn come from the underlying dynamics. Thus, an accurate description of the flow which includes hydrodynamics and radiative transfer is a must to interpret the observational results. In the case of non-rotating black holes, Pseudo- Newtonian description of surrounding space-time enables one to make a significant progress in predicting spectral and timing properties. This formalism is lacking for the spinning black holes. In this paper, we show that there exists an exact form of ‘natural’ potential derivable from the general relativistic (GR) radial momentum equation written in the local corotating frame. Use of this potential in an otherwise Newtonian set of equations, allows us to describe transonic flows very accurately as is evidenced by comparing with solutions obtained from the full GR framework. We study the properties of the sonic points and the centrifugal pressure supported shocks in the parameter space spanned by the specific energy and the angular momentum, and compare with the results of GR hydrodynamics. We show that this potential can safely be used for the entire range of Kerr parameter −1 < a < 1 for modeling of observational results around spinning black holes. We assume the flow to be inviscid. Thus, it is non-dissipative with constant energy and angular momentum. These assumptions are valid very close to the black hole horizon as the infall time scale is much shorter as compared to the viscous time scale.

SPACE DISCOURSE IN A LANGUAGE CONTACT SITUATION: “US” VS. “THEM”

Multilingual practices inevitably lead to language contact phenomena. This phenomenon occurs in Estonia, where the Russian speaking minority, often defined as a Russian diaspora, differs from the socially and linguistically dominant Estonian group with respect to their language and language practices. We suggest that the analysis of one of the languages in contact, in this case Russian, allows for a deeper understanding of the role of the other, i.e. Estonian, in the multilingual practices of the Estonian population as a whole. In this paper, we will focus on “spatial indicators” (i.e. toponyms, ergonyms, linguistic landscape objects, etc.) in the discourse on space provided by participants from the Russian-speaking population living in Estonia. These sociolinguistic foci have been partially described in several existing works which underscore the influence of Estonian on the speech of the local Russian speakers. Previous research gives insights into the peculiarities that the influence of Estonian generates: in the use of toponyms, in the naming of different language landscape objects, in the everyday language practices, and in the description and evaluation of the surrounding space (i.e. in the “spatial awareness”) of the local Russian speaking population. However, little attention has been paid to the fact that the aforementioned phenomena represent a whole that reflects the development of the speakers’ apprehension of the surrounding physical, sociocultural and sociolinguistic space. This process is put into focus in this paper and is shown to be characterized by the (re)definition of space(s) as “ours” vs “theirs”. Such processes will be revealed here by giving an overview of the “spatial components” in the speech of the Russian speaking population of Estonia in several spheres of communication (newspapers, TV shows, advertisements, web forums, etc.) and by analysing interviews involving three Estonian residents, each with a different sociolinguistic background. We attempt to demonstrate how these “spatial components” reflect the interaction of Russian and Estonian speakers, with an emphasis on their affinities across certain language practices. In the analysis of the interviews, we focus in particular on the participants’ (re)definitions of “us” vs “them” in their discourse on space. Special attention is also given to the use of Estonian insertions as a tool for evaluation and the creation of the opposition between “us” and “them” in the internet communication of Russian speakers living in Estonia.

Sound: production, perception, hearing loss & treatment options

Sound is an important communication tool for humans that contain information about the surrounding environment. It may signify a danger or a reward for an organism. In humans, the mechanism of sound production and perception is complex and sophisticated. Sound is produced by vibrating body in a medium that contains molecules in the surrounding space. The sound perception starts in human foetus at around the third trimester where it plays a vital role in organising the foetal brain. This process continues after birth and can be exploited by various endogenous and exogenous factors. Many mechanisms that can modulate hearing process at different levels lead to subclinical or clinical presentation of hearing-related problems. It is important to contemplate the mechanisms underlying sound production, perception and pathogenesis of hearing loss. This will facilitate prescribing a relevant treatment option according to the cause and its underlying mechanism. --Continue

Conclusion and Further Discussion

The readers of this book have taken note of the history of site-specific installation art and were offered an analytical model for examining the perpetuation of the artworks in a museum context. As the term suggests, site-specific installations are physically tied to the surrounding space and would, strictly speaking, have no afterlives after their initial manifestation. However, as demonstrated with many examples, site-specific installations can have extended lives and are frequently relocated to different contexts and times. Hence, rather than defining site specificity as a “fixed” characteristic, this study took a broader perspective by looking into the biographies of the artworks in relation to the exhibition site, ongoing institutional engagement, the locations of production, and the visitors’ interaction in the here and now.

GIS-based NNA and Kernel Density Analysis for Identifying Distribution of Restaurant’s Popularity Index in Bandung

With the advancement of information and communication technology, geographic information systems (GIS) also grow. The existence of GIS allows problems to be solved as much as possible by paying attention to the surrounding space. GIS applications have been widely applied in everyday life including in the culinary field. The existence of GIS in the culinary field can make it easier to find location information where a restaurant is located and find out how the restaurant’s popularity index is. This research focuses on using NNA and KDA to analyze distribution patterns formed from each classification of restaurant popularity index in Bandung and the density of the restaurant point. Restaurant data containing restaurant names, restaurant addresses, restaurant types, food types, and restaurant popularity indexes were obtained from Zomato using Zomato’s Application Programming Interface (API). The result of this research are spatial distribution pattern of the high, medium, and low popularity restaurants in Bandung City showing the same characteristics, clustering and has a large density in several sub-districts.

The Impact of Temporary Means of Access on Buildings Envelope’s Maintenance Costs

Accessibility to buildings’ envelope depends on efficient inspection and other maintenance actions of their components. When access to these components is not planned, special means of access are required to carry out the maintenance work. Means of access, besides having a fundamental role on the quality of maintenance works of building envelope components, also represents a considerable part of the maintenance costs. Thus, to optimize costs and resources in maintenance plans, assessment of the impact of the means of access on maintenance costs is crucial. For works in height, there are several alternative means of access. The choice of the most adequate solution is strongly linked to the characteristics (e.g., architecture, height) and constraints (e.g., users, surrounding space) of each building, the maintenance needs of the envelope, and the time and funds available for the intervention. Therefore, in this study, a sensitivity analysis to understand how the cost of means of access can influence the maintenance costs is carried out. Moreover, the optimisation of maintenance activities in façade claddings is also analysed. This study intends to assess whether it is advantageous to consider permanent means of access during the design phase or opt for temporary means of access. In a first stage, the impact of six temporary means of access (supported and suspended scaffolds; articulated booms; telescopic booms; scissor lifts; and rope access) on the maintenance plans developed for the six types of claddings (ceramic tiling systems—CTS, natural stone claddings—NSC, rendered façades—RF, painted surfaces—PS, external thermal insulation composite systems—ETICS, and architectural concrete façades—ACF) is examined. The impact is estimated through a stochastic maintenance model based on Petri nets. After that, a sensitivity analysis and a multi-criteria decision analysis are performed. Based on the results, general recommendations are presented concerning the maintenance strategies to adopt in the cladding solutions analysed. The results reveal that planning the means of access during the design stage can be economically beneficial for all buildings’ envelope components.

Color in Selected Artistic Glass Compositions by Tomasz Urbanowicz as an Element of Intervention in Historic Buildings and Contemporary Architecture

Colored glass in the form of stained-glass windows has been used to decorate buildings for over a thousand years. Due to various late-twentieth-century technological achievements, this material allows for a broad spectrum of design solutions. Glass can be used both in contemporary and historical buildings. This paper presents an analysis of the work of Tomasz Urbanowicz, an artist who works with glass, and its objective is to present not only the body of work of this artist but also the means of using colored glass in creating new values in architecture. The work is based on a study of the literature that covers the contemporary application of colored glass, on-site analysis of projects, and a series of interviews with the artist before, during, and after project completion, as well as the authors’ personal experience in the matter. One of the main research methods used was an analysis of the artist’s stance, as to him, the very process of pursuing creative inspiration is a fundamental procedure. Glassworks by Urbanowicz were displayed at the EXPO 2000 in Hanover (Germany), the EXPO 2005 in Aichi (Japan), and the EXPO 2008 in Saragossa (Spain). The United Earth glass sphere has been decorating the agora of the European Parliament building in Strasbourg (France) since 2004. In the paper, the artist’s projects are presented in two groups: The first includes solutions that employ monochromatic color schemes, whereas in the second, color has been used to create a strong contrast. The analysis presented includes interventions in historical buildings under heritage conservation, but also compositions from architectural glass in newly built buildings and that reference place-based history. Both the initial vision and the final effect of the glass architectural compositions are site-specific. The analysis of these differences and how the artist works allowed us to formulate a scheme of how he operates. Urbanowicz’s glass interventions affect the quality of the spaces they create and highlight their existing or expected features. The influence of the works can either play a primary and dominant role in relation with the surrounding space or be a secondary and delicate addition. Applied color may have different functions, from highlighting specific aspects of a building to introducing symbolic or direct reference. In many projects, color works as a source of a building interior’s atmosphere. The artistic interventions in historic spaces emphasize their features without disrupting pre-existing authenticity, whereas contemporary projects with no historic reference offer a wide variety of color applications that focus on the function and form of architecture, landscape, or surroundings.

An Analysis of an Area’s Vulnerability to the Emergence of Land-Use Conflicts

The optimization of space is the priority goal of spatial planning. Spatial planning policies have numerous objectives, including the prevention of land-use conflicts. Conflicts arise whenever two entities have contradictory expectations regarding the surrounding space. In the process of spatial development, humans impart new characteristics to space, which, under specific circumstances, can give rise to land-use conflict. The elements of space that are particularly vulnerable to conflict include boundary points, property boundaries, density of development, or the shared use of infrastructure. The main aim of this study was to develop a procedure for evaluating the risk of land-use conflict based on the characteristic attributes of space. The proposed procedure for assessing the accumulation of conflict-generating traits in space was developed with the use of databases, GIS tools, and statistical data processing methods.

Features of intensive evaporation of liquid-metal steel drops heated in a high-frequency inductor

The paper presents the results of experimental studies of the processes of intense melting in air of samples (solid balls) made of metals, primarily various steels. It is shown that the heating of some steels is accompanied by intense sparking - the ejection of small secondary droplets (sparks) from the primary droplet heated up to 2500 K into the surrounding space. A possible mechanism of this process is proposed and described at a qualitative level. Possible reasons for the explosive fragmentation of secondary droplets are indicated and experimentally confirmed. The vibration process of molten samples shell, caused by the vortex motion and evaporation of the melt inside the droplet, is described. The influence of spark formation on the stability of the induction melting process is demonstrated.

Features of the use of quartz sand as a vibration damping spacer for internal combustion engine muffler housing

Evaluation of acoustic characteristics of an internal combustion engine (ICE) takes into account its capability to reduce gas dynamic noise from exhausted gases as well as the level of structural (housing) noise emitted by the dynamically excited housing. The muffler housing is dynamically excited in a mechanical way from an ICE vibrating on the suspension as well as by a pulsating flow of exhaust gases transmitting vibration energy via hard support ties of rubber metallic suspension supports on the vehicle frame or body and emitting sound to the surrounding space. One of the methods to reduce the level of muffler housing noise is making the housing double-layered with internal and external walls made of metal, or making it triple-layered containing a vibration damping spacer between the internal and external walls. An efficient solution is the use of a loose vibration damping substances represented by quartz sand as a vibration damping spacer. The article considers the study results of structural sound levels emitted by triple-layered walls of an ICE muffler depending on the bulk density of quartz sand used as a vibration damping spacer between muffler housing walls.