scholarly journals Evaluation of the search and rescue LEEWAY model in the Tyrrhenian Sea: a new point of view

2016 ◽  
Vol 16 (8) ◽  
pp. 1979-1997 ◽  
Author(s):  
Antonia Di Maio ◽  
Mathew V. Martin ◽  
Roberto Sorgente
Keyword(s):  
Boundary Layer ◽  
Point Of View ◽  
Search And Rescue ◽  
Force Balance ◽  
Tyrrhenian Sea ◽  
New Approach ◽  
Search Area ◽  
Real Person ◽  
Floating Objects ◽  
Force Balance Equation

Abstract. The trajectories' prediction of floating objects above the sea surface represents an important task in search and rescue (SAR) operations. In this paper we show how it is possible to estimate the most probable search area by means of a stochastic model, schematizing the shape of the object appropriately and evaluating the forces acting on it. The LEEWAY model,a Monte Carlo-based ensemble trajectory model, has been used; here, both statistical law to calculate the leeway and an almost deterministic law inspired by the boundary layer theory have been considered. The model is nested within the subregional hydrodynamic model TSCRM (Tyrrhenian Sicily Channel Regional Model) developed in the framework of PON-TESSA (Programma Operativo Nazionale; National Operative Program – TEchnology for the Situational Sea Awareness) project. The main objective of the work is to validate a new approach of leeway calculation that relies on a real person in water (PIW) event, which occurred in the Tyrrhenian Sea in July 2013. The results show that by assimilating a human body to a cylinder and estimating both the transition from laminar to turbulent boundary layer and the drag coefficients, it can be possible to solve a force balance equation, which allows the search area to be estimated with good approximation. This new point of view leads to the possibility of also testing the same approach for other different categories of targets, so as to overcome the limitations associated with the calculation of the leeway in the future by means of standard statistical law.

scholarly journals Evaluation of the Search and Rescue Leeway model into the Tyrrhenian sea: a new point of view

2016 ◽  
Author(s):  
Antonia Di Maio ◽  
Mathew Vayalumkal Martin ◽  
Roberto Sorgente
Keyword(s):  
Boundary Layer ◽  
Regional Model ◽  
Boundary Layer Theory ◽  
Point Of View ◽  
Search And Rescue ◽  
Sea Surface ◽  
Tyrrhenian Sea ◽  
New Approach ◽  
Search Area ◽  
Floating Objects

Abstract. The trajectories prediction of the floating objects above the sea surface represents an important task in the search and rescue (SAR) operations. In this paper we show how may be possible estimate the most probable search area by means of a stocastic model, schematizing appropriately the shape of the object and evaluating the forces acting on it. The LEEWAY model, a Montecarlo-based ensemble trajectory model, has been used; here not only the statistical law to calculate the leeway is employed but also an almost deterministic law inspired by the boundary layer theory. The model is nested with the sub-regional hydrodynamic model TSCRM (Thyrrenian Sicily Channel Regional Model) developed in the framework of PON-TESSA (National Operative Programs-TEchnology for the Situational Sea Awareness) project. The principal objective of the work is to validate the new approach of leeway calculation relying on a real event of Person in Water (PIW), occurred on July 2013 in the Thyrrenian Sea. The results show that assimilating a human body to a cylinder and estimating either the transition from laminar to turbulent boundary layer and the drag coefficients, may be possible to solve a forces balance equation which permits to estimate with good approximation the search area. This new point of view leads to the possibility to check the same approach also on other different categories of targets, so as to overcome in the future the limitations associated with calculation of leeway by means of the standard statistical law.

scholarly journals Controllability and Observability of a Large Scale Thermodynamical System via Connectability Approach

2010 ◽  
Author(s):  
Virdiansyah Permana ◽  
Rahmat Shoureshi
Keyword(s):  
Graph Theory ◽  
Lie Algebra ◽  
Large Scale ◽  
Point Of View ◽  
Rank Condition ◽  
Computational Point ◽  
New Approach ◽  
Class System ◽  
Necessary And Sufficient ◽  
Controllability And Observability

This study presents a new approach to determine the controllability and observability of a large scale nonlinear dynamic thermal system using graph-theory. The novelty of this method is in adapting graph theory for nonlinear class and establishing a graphic condition that describes the necessary and sufficient terms for a nonlinear class system to be controllable and observable, which equivalents to the analytical method of Lie algebra rank condition. The directed graph (digraph) is utilized to model the system, and the rule of its adaptation in nonlinear class is defined. Subsequently, necessary and sufficient terms to achieve controllability and observability condition are investigated through the structural property of a digraph called connectability. It will be shown that the connectability condition between input and states, as well as output and states of a nonlinear system are equivalent to Lie-algebra rank condition (LARC). This approach has been proven to be easier from a computational point of view and is thus found to be useful when dealing with a large system.

Static Determinacy in the Theory of Finite Width Foil Bearings

1974 ◽  
Vol 41 (1) ◽  
pp. 51-54 ◽  
Author(s):  
W. E. Langlois
Keyword(s):  
Force Balance ◽  
Finite Width ◽  
Foil Bearings ◽  
Lubrication Equation ◽  
Foil Bearing ◽  
Edge Conditions ◽  
Single Force ◽  
Static Determinacy ◽  
Force Balance Equation ◽  
Determinate Problem

The assumption of “perfect flexibility” is shown to be self-consistent in an important class of finite-width foil bearing problems. When the membrane equations are written in the “stretched coordinates” of foil bearing theory, the usual edge conditions on the tape result in a statically determinate problem. The tape dynamics couples to the Reynolds lubrication equation through a single force-balance equation which does not entail the elastic strain.

Numerical Investigation of the Combined Effects of Biomolecular Adsorption and Microdroplet Evaporation on the Performance of the Electrocapillary-Based Digital Microfluidic Systems

2011 ◽  
Author(s):  
Ali Ahmadi ◽  
Mina Hoorfar
Keyword(s):  
Mass Loss ◽  
Protein Concentration ◽  
Adsorption Rate ◽  
Force Balance ◽  
Combined Effects ◽  
Microfluidic Systems ◽  
Gibbs Equation ◽  
Rate Effects ◽  
Digital Microfluidic ◽  
Force Balance Equation

In this article, microdroplet motion in the electrocapillary-based digital microfluidic systems is modeled accurately, and the combined effects of the biomolecular adsorption and micro-droplet evaporation on the performance of the device are investigated. An electrohydrodynamic approach is used to model the driving and resisting forces, and Fick’s law and Gibbs equation are used to calculate the microdroplet evaporation and adsorption rate. Effects of the adsorption and evaporation rates are then implemented into the microdroplet dynamics by adding new terms into the force balance equation. It is shown that mass loss due to the evaporation tends to increase the protein concentration, and on the other hand, the increased concentration due to the mass loss increases the biomolecular adsorption rate which has a reverse effect on the concentration. The modeling results indicate that evaporation and adsorption play crucial roles in the microdroplet dynamics.

scholarly journals Effective Buoyancy, Inertial Pressure, and the Mechanical Generation of Boundary Layer Mass Flux by Cold Pools

2015 ◽  
Vol 72 (8) ◽  
pp. 3199-3213 ◽  
Author(s):  
Nadir Jeevanjee ◽  
David M. Romps
Keyword(s):  
Boundary Layer ◽  
Mass Flux ◽  
Dominant Role ◽  
Deep Convection ◽  
Force Balance ◽  
Vertical Force ◽  
Inertial Forces ◽  
Buoyancy Forcing ◽  
Cold Pools ◽  
Gust Front

Abstract The Davies-Jones formulation of effective buoyancy is used to define inertial and buoyant components of vertical force and to develop an intuition for these components by considering simple cases. This decomposition is applied to the triggering of new boundary layer mass flux by cold pools in a cloud-resolving simulation of radiative–convective equilibrium (RCE). The triggering is found to be dominated by inertial forces, and this is explained by estimating the ratio of the inertial forcing to the buoyancy forcing, which scales as H/h, where H is the characteristic height of the initial downdraft and h is the characteristic height of the mature cold pool’s gust front. In a simulation of the transition from shallow to deep convection, the buoyancy forcing plays a dominant role in triggering mass flux in the shallow regime, but the force balance tips in favor of inertial forcing just as precipitation sets in, consistent with the RCE results.

Performing the ‘lifeworld’ in public education campaigns

2010 ◽  
Vol 1 (2) ◽  
pp. 284-310 ◽  
Author(s):  
Michelle M. Lazar
Keyword(s):  
Public Education ◽  
Rap Music ◽  
Dual Processes ◽  
Public Performance ◽  
New Approach ◽  
The Public ◽  
Local Television ◽  
The Media ◽  
Education Campaigns ◽  
Real Person

In Singapore, top down public education campaigns have long been a mode of governance by which the conduct of citizens is constantly regulated. This article examines how in two fairly recent campaigns, a new approach to campaign communication is used that involves media interdiscursivity, viz., the mixing of discourses and genres in which the media constitute a significant element. The present approach involves the appropriation of a popular local television character, ‘Phua Chu Kang’, in order to address the public through educational rap music videos. Media interdiscursivity is based on an attempt to engage the public via a discourse of the ‘lifeworld’. The present article analyzes the ‘lifeworld’ discourse in terms of a combination of two processes, ‘informalization’ (the use of informal and conversational modes of address) and ‘communitization’ (the semiotic construction of a community of people). The dual processes are examined and discussed in relation to the choice of Phua Chu Kang as an ‘ordinary’ and almost ‘real’ person, including his informal register and speech style; his use of Singlish; and his construction of ‘community.’ The presence of Singlish, in particular, is interesting because (despite the official disdain for the language) it is included as part of PCK’s public performance of the lifeworld. The article concludes by considering this form of media interdiscursivity as the government’s shrewd way of achieving its social governance goals.

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