scholarly journals A New Approach to Evaluate Planetary Perturbations on a Cloud of Dust in Low Eccentricity Heliocentric Orbits

1985 ◽  
Vol 85 ◽  
pp. 381-384 ◽  
Author(s):  
Bo. Å. S. Gustafson
Keyword(s):  
Dust Cloud ◽  
Frame Of Reference ◽  
Orbital Elements ◽  
New Approach ◽  
Gravitational Perturbations ◽  
Time Integral ◽  
Common Coordinate System ◽  
Heliocentric Orbits ◽  
Single Matrix ◽  
Over Time

AbstractDynamical perturbations on ensembles of particles in heliocentric orbits of low eccentricity are integrated over time. The dust is perturbed by radiation pressure, Poynting-Robertson drag, their corpuscular counterparts, and by gravitation due to any number of planets. A dust cloud is represented by a set of centroids and orbital dispersions (about the centroids). Gravitational perturbations on the centroid are derived from a single matrix, valid for any planet, in the appropriate frame of reference. After transformation of the time derivatives to a common coordinate system, the perturbation rates are summed up and integrated. The time dependence of the planets’ orbital elements are evaluated inside the time integral.

scholarly journals Measuring Poverty in Britain as a Multi-dimensional Concept, 1991 to 2003

2008 ◽  
Vol 37 (4) ◽  
pp. 597-620 ◽  
Author(s):  
MARK TOMLINSON ◽  
ROBERT WALKER ◽  
GLENN WILLIAMS
Keyword(s):  
Structural Equation Modelling ◽  
Structural Equation ◽  
Panel Study ◽  
Financial Stress ◽  
Material Deprivation ◽  
New Approach ◽  
Equation Modelling ◽  
Dimensional Measure ◽  
Trends Over Time ◽  
Over Time

AbstractWhile poverty is widely accepted to be an inherently multi-dimensional concept, it has proved very difficult to develop measures that both capture this multi-dimensionality and facilitate comparison of trends over time. Structural equation modelling appears to offer a solution to this conundrum and is used to exploit the British Household Panel Study to create a multi-dimensional measure of poverty. The analysis reveals that the decline in poverty in Britain between 1991 and 2003 was driven by falls in material deprivation, but more especially by reduced financial stress, particularly during the early 1990s. The limitations and potential of the new approach are critically discussed.

Logica di un sistema di sostegno alle imprese. La politica industriale italiana dal secondo dopoguerra a "Industria 2015"

2009 ◽  
pp. 89-113
Author(s):  
Fabrizio Traů
Keyword(s):  
Industrial Policy ◽  
State Intervention ◽  
State Aid ◽  
Limiting State ◽  
New Approach ◽  
Industrial Activities ◽  
The Universe ◽  
Over Time

- The paper aims at discussing the logic lying behind sixty years of industrial policy in Italy. It is argued that during this time State intervention has been characterised by the issue of an increasing number of laws (mostly persisting over time) devoted to specific objectives, but at the same time paralleled by a tendency towards the reduction of their selectivity through the widening (i.e. the loosening) of the boundaries of the universe of firms they were thought for. Such a logic seems to have made way in recent years for a relatively new approach, as stated in the program "Industria 2015", which has put at the centre of the stage the need for limiting State aid to a selected group of (horizontally identified) industrial activities. The paper also discusses some apparent shortcomings of this approach, emphasising that a risk for a new weakening of its selective logic is still at work.

5 Years, 20 Issues, 141 Articles, and What?

1996 ◽  
Vol 6 (3) ◽  
pp. 327-358
Author(s):  
LaRue Tone Hosmer
Keyword(s):  
New Approach ◽  
Conceptual Definition ◽  
Major Trend ◽  
Over Time

AbstractThe first issue of BusinessEthics Quarterlyappeared five years ago. This article classifies the content of the 141 articles that have appeared since that time along 18 dimensions, and 118 categories within those dimensions, to determine trends within the discipline. The major trend appears to be a shift in focus towards the increased discussion of a new approach/paradigm for the field, and towards a normative/descriptive interface of the theory. The major problem seems to be a lack of explicit conceptual definition and beginning empirical effort to support that new focus, which may thus prove unsustainable over time.

scholarly journals A Semi-Supervised Learning Approach for Tackling Twitter Spam Drift

2019 ◽  
Vol 18 (02) ◽  
pp. 1950010 ◽  
Author(s):  
Niddal Imam ◽  
Biju Issac ◽  
Seibu Mary Jacob
Keyword(s):  
Machine Learning ◽  
Supervised Learning ◽  
Research Community ◽  
Machine Learning Techniques ◽  
Spam Detection ◽  
Learning Approach ◽  
New Approach ◽  
Detection Systems ◽  
Learning Techniques ◽  
Over Time

Twitter has changed the way people get information by allowing them to express their opinion and comments on the daily tweets. Unfortunately, due to the high popularity of Twitter, it has become very attractive to spammers. Unlike other types of spam, Twitter spam has become a serious issue in the last few years. The large number of users and the high amount of information being shared on Twitter play an important role in accelerating the spread of spam. In order to protect the users, Twitter and the research community have been developing different spam detection systems by applying different machine-learning techniques. However, a recent study showed that the current machine learning-based detection systems are not able to detect spam accurately because spam tweet characteristics vary over time. This issue is called “Twitter Spam Drift”. In this paper, a semi-supervised learning approach (SSLA) has been proposed to tackle this. The new approach uses the unlabeled data to learn the structure of the domain. Different experiments were performed on English and Arabic datasets to test and evaluate the proposed approach and the results show that the proposed SSLA can reduce the effect of Twitter spam drift and outperform the existing techniques.

scholarly journals A new approach for satisfactory pensions with no guarantees

2019 ◽  
Vol 10 (1) ◽  
pp. 3-21
Author(s):  
M. Carmen Boado-Penas ◽  
Julia Eisenberg ◽  
Axel Helmert ◽  
Paul Krühner
Keyword(s):  
Risk Management ◽  
Interest Rates ◽  
Asset Management ◽  
Expected Return ◽  
New Approach ◽  
Low Interest Rates ◽  
Key Variables ◽  
Pension Benefits ◽  
Pension Payments ◽  
Over Time

AbstractThe increase in longevity, the ultra-low interest rates and the guarantees associated to pension benefits have put significant strain on the pension industry. Consequently, insurers need to be in a financially sound position while offering satisfactory benefits to participants. In this paper, we propose a pension design that goes beyond the idea of annuity pools and unit-linked insurance products. The purpose is to replace traditional guarantees with low volatility, mainly achieved by collective smoothing algorithms and an adequate asset management. With the aim of offering security to the insured, we discuss the optimisation of some key variables of the proposed pension product to target both a satisfactory level of the initial pension and stable pension payments over time. By combining such well-known products as unit-linked and annuities, we show that it is possible to design a pension product with both high-expected return and low risk for the policyholder. However, differently than in the classical unit-linked framework, we do not allow the individuals to choose the underlying funds. Instead, the funds are under the surveillance of an insurance company’s professional risk management, which induces better informed decisions.

scholarly journals New HST data and modeling reveal a massive planetesimal collision around Fomalhaut

2020 ◽  
Vol 117 (18) ◽  
pp. 9712-9722 ◽  
Author(s):  
András Gáspár ◽  
George H. Rieke
Keyword(s):  
Planetary System ◽  
Hubble Space Telescope ◽  
Dust Cloud ◽  
Planetary Systems ◽  
Orbital Evolution ◽  
Published Data ◽  
Space Telescope ◽  
Gravitational Perturbations ◽  
Extrasolar Planetary System

The apparent detection of an exoplanet orbiting Fomalhaut was announced in 2008. However, subsequent observations of Fomalhaut b raised questions about its status: Unlike other exoplanets, it is bright in the optical and nondetected in the infrared, and its orbit appears to cross the debris ring around the star without the expected gravitational perturbations. We revisit previously published data and analyze additional Hubble Space Telescope (HST) data, finding that the source is likely on a radial trajectory and has faded and become extended. Dynamical and collisional modeling of a recently produced dust cloud yields results consistent with the observations. Fomalhaut b appears to be a directly imaged catastrophic collision between two large planetesimals in an extrasolar planetary system. Similar events should be very rare in quiescent planetary systems of the age of Fomalhaut, suggesting that we are possibly witnessing the effects of gravitational stirring due to the orbital evolution of hypothetical planet(s) around the star.

scholarly journals A New Approach to Risk Attribution and Its Application in Credit Risk Analysis

Risks ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 65
Author(s):  
Christoph Frei
Keyword(s):  
Risk Factors ◽  
Risk Analysis ◽  
Credit Risk ◽  
Driving Factors ◽  
New Approach ◽  
Risk Decomposition ◽  
Risk Attribution ◽  
Credit Risk Analysis ◽  
A Company ◽  
Over Time

How can risk of a company be allocated to its divisions and attributed to risk factors? The Euler principle allows for an economically justified allocation of risk to different divisions. We introduce a method that generalizes the Euler principle to attribute risk to its driving factors when these factors affect losses in a nonlinear way. The method splits loss contributions over time and is straightforward to implement. We show in an example how this risk decomposition can be applied in the context of credit risk.

scholarly journals Reducing light scattering from surface contaminations by thin film design

2017 ◽  
Vol 6 (5) ◽  
Author(s):  
Alexander von Finck ◽  
Steffen Wilbrandt ◽  
Olaf Stenzel ◽  
Sven Schröder
Keyword(s):  
Thin Film ◽  
Light Scattering ◽  
State Of The Art ◽  
Stray Light ◽  
New Approach ◽  
Film Coatings ◽  
Thin Film Coatings ◽  
Particle Contamination ◽  
Coating Design ◽  
Over Time

AbstractIn most applications, contamination of optical thin film coatings is inevitable over time. State-of-the art approaches to tackle this problem are usually based on two strategies – avoiding contamination or removing already existing contamination. We demonstrate that the coating design can be tailored to reduce light scattering and stray light arising from particle contamination. This allows reducing the optical symptoms (light scattering) rather than trying to address the inevitable cause of the problem (contamination) itself. This new approach can consequently be easily combined with state-of-the-art approaches.

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