scholarly journals Aerodynamic and impact thresholds for cohesive mixture of sand and non-volatile liquid

2021 ◽  
Vol 249 ◽  
pp. 08007
Author(s):  
Jean-Baptiste Besnard ◽  
Alexandre Valance ◽  
Pascal Dupont ◽  
Ahmed Ould El Moctar

The moisture has been recognized to have a significant influence on the initiation movement of sand by wind and consequently on sand transport rates. The pertinent literature regarding these phenomena is sparse and current available theoretical and empirical models exhibit considerable disagreement regarding the magnitude of moisture effects. We believe that these discrepancies comes from the fact that the moisture levels are not well controlled neither properly measured and are susceptible to strongly vary over time due to evaporation. To get rid of the variability of moisture content due to evaporation, we propose a new approach based on the use of non-volatile liquid, namely silicon oil instead of water. This insures a proper control of the liquid content and the production of reliable data concerning the variation of the transport threshold with liquid content.

2008 ◽  
Vol 37 (4) ◽  
pp. 597-620 ◽  
Author(s):  
MARK TOMLINSON ◽  
ROBERT WALKER ◽  
GLENN WILLIAMS

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.


2009 ◽  
pp. 89-113
Author(s):  
Fabrizio Traů

- 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.


1996 ◽  
Vol 6 (3) ◽  
pp. 327-358
Author(s):  
LaRue Tone Hosmer

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.


Eos ◽  
2020 ◽  
Vol 101 ◽  
Author(s):  
Rachel Fritts

New research provides a more accurate model that coastal managers and engineers can use to account for sand transport over time.


Pirate Lands ◽  
2021 ◽  
pp. 98-118
Author(s):  
Ursula Daxecker ◽  
Brandon Prins

This chapter models and empirically tests the cross-national correlates of contemporary commerce raiding. The chapter theoretically examines how state capacity at the center influences the rate of pirate attacks in the territorial waters and Exclusive Economic Zones of states. But it also recognizes that several other conditions help drive ship attacks, including privation, target opportunity, armed conflict, and the labor supply. The empirical models control for these factors when assessing cross-national and over-time variation in maritime piracy. Using multiple measures of state capacity, the chapter shows that pirates gravitate toward states that are weak at the center. It also finds that countries with larger populations, longer coastlines, proximity to maritime choke points, and poor economic conditions witness more pirate attacks. The last section discusses how to move from national capacity in the analyses presented in this chapter to subnational capacity in the next two chapters.


1985 ◽  
Vol 85 ◽  
pp. 381-384 ◽  
Author(s):  
Bo. Å. S. Gustafson

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.


Author(s):  
Niddal Imam ◽  
Biju Issac ◽  
Seibu Mary Jacob

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.


2019 ◽  
Vol 10 (1) ◽  
pp. 3-21
Author(s):  
M. Carmen Boado-Penas ◽  
Julia Eisenberg ◽  
Axel Helmert ◽  
Paul Krühner

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.


Risks ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 65
Author(s):  
Christoph Frei

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.


Sign in / Sign up

Export Citation Format

Share Document