7,275 research outputs found
Finite-Amplitude Instability of the Compressible Laminar Wake. Strongly Amplified Disturbances
The interaction between mean flow and finiteâamplitude disturbances in certain experimentally observed unstable, compressible laminar wakes is considered theoretically without explicitly assuming small amplification rates. Boundaryâlayer form of the twoâdimensional meanâflow momentum, kinetic energy and thermal energy equations and the timeâaveraged kinetic energy equation of spatially growing disturbances are recast into their respective von KĂĄrmĂĄn integral form which show the overâall physical coupling. The Reynolds shear stresses couple the mean flow and disturbance kinetic energies through the conversion mechanism familiar in lowâspeed flows. Both the mean flow and disturbance kinetic energies are coupled to the meanâflow thermal energy through their respective viscous dissipation. The work done by the disturbance pressure gradients gives rise to an additional coupling between the disturbance kinetic energy and the meanâflow thermal energy. The compressibility transformation suggested by work on turbulent shear flows is not applicable to this problem because of the accompanying ad hoc assumptions about the disturbance behavior. The disturbances of a discrete frequency which corresponds to the most unstable fundamental component, are first evaluated locally. Subsequent meanâflow and disturbance profileâshape assumptions are made in terms of a meanâflowâdensity Howarth variable. The compressibility transformation, which cannot convert this problem into a form identical to the lowâspeed problem of Ko, Kubota, and Lees because of the compressible disturbance quantities, nevertheless, yields a much simplified description of the mean flow
Interactivity within IMS Learning Design and Question and Test Interoperability
We examine the integration of IMS Question and Test Interoperability (QTI) and IMS Learning Design (LD) in implementations of E-learning from both pedagogical and technological points of view. We propose the use of interactivity as a parameter to evaluate the quality of assessment and E-learning, and assess various cases of individual and group study for their interactivity, ease of coding, flexibility, and reusability. We conclude that presenting assessments using IMS QTI provides flexibility and reusability within an IMS LD Unit Of Learning (UOL) for individual study. For group study, however, the use of QTI items may involve coding difficulties if group members need to wait for their feedback until all students have attempted a question, and QTI items may not be able to be used at all if the QTI services are implemented within a service-oriented architecture
An evaluation of MAAPâs Train the Simulator Trainer and Assessor (IMO Model Course 6.10): traineesâ perspectives and reverberations
The study aims to analyze how the trainees evaluate the âTrain the simulator trainer and assessorâ (IMO Model Course 6.10) provided by the Maritime Academy of Asia and the Pacific (MAAP) for free in cooperation with the Maritime Industry Authority (MARINA) and the Commission on Higher Education (CHED). The training is regularly rendered as one of the extension services of MAAP. The study utilized the data from the evaluation form accomplished by the eight batches corresponding to 94 trainees in 2019. Results showed that the trainees regarded the training as âExcellentâ in terms of the General Information. The trainees likewise rated the training as âExcellentâ in terms of the Topics/Exercises. Statistics showed that there was no significant difference between the evaluation of the trainees on the training on IMO Model Course 6.10 when they are grouped according to batches both in General Information and Topics/Exercises
Exhaust-valve Temperatures in a Liquid-cooled Aircraft-engine Cylinder as Affected by Engine Operating Variables
Enamel of Yalkaparidon Coheni: Representative of a Distinctive Order of Tertiary Zalambdodont Marsupials
The enamel of an incisor and a premolar of Yalkaparidon coheni was examined by scanning electron microscopy in fractured and in sectioned, polished surfaces. The enamel of both teeth demonstrated: complete, ovoid and horse-shoe shaped prisms in a Pattern 2 arrangement; a simple parallel prism course; and, enamel tubules in abundance in the premolar but restricted to the innermost enamel in the incisor. Overall, the enamel ultrastructure supports the marsupial affiliation proposed for Yalkaparidon coheni but does not unambiguously ally it with any other order of marsupials.
The observation of a significant ultrastructural difference between the anterior and posterior teeth of a marsupial emphasizes the need to sample both if available. In pursuing this, we report here also the lack of tubules in the anterior teeth of the extant Tarsipes rostratus. This together with a similar absence of typical marsupial tubules from the incisor of the extinct Yalkaparidon coheni, would suggest that the wombat is not the only surviving marsupial to have experimented so extensively with this particular structural feature. It is likely that further study will demonstrate an unexpected and relative lack of tubules in the incisor enamel of other fossil Australian marsupials
An evaluation of metal removal during wastewater treatment: The potential to achieve more stringent final effluent standards
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2011 Taylor & Francis.Metals are of particular importance in relation to water quality, and concern regarding the impact of these contaminants on biodiversity is being encapsulated within the latest water-related legislation such as the Water Framework Directive in Europe and criteria revisions to the Clean Water Act in the United States. This review undertakes an evaluation of the potential of 2-stage wastewater treatment consisting of primary sedimentation and biological treatment in the form of activated sludge processes, to meet more stringent discharge consents that are likely to be introduced as a consequence. The legislation, sources of metals, and mechanisms responsible for their removal are discussed, to elucidate possible pathways by which the performance of conventional processes may be optimized or enhanced. Improvements in effluent quality, achievable by reducing concentrations of suspended solids or biochemical oxygen demand, may also reduce metal concentrations although meeting possible requirements for the removal of copper my be challenging
Mass Determination in SUSY-like Events with Missing Energy
We describe a kinematic method which is capable of determining the overall
mass scale in SUSY-like events at a hadron collider with two missing (dark
matter) particles. We focus on the kinematic topology in which a pair of
identical particles is produced with each decaying to two leptons and an
invisible particle (schematically, followed by each
decaying via where is invisible). This topology
arises in many SUSY processes such as squark and gluino production and decay,
not to mention t\anti t di-lepton decays. In the example where the final
state leptons are all muons, our errors on the masses of the particles ,
and in the decay chain range from 4 GeV for 2000 events after cuts to 13
GeV for 400 events after cuts. Errors for mass differences are much smaller.
Our ability to determine masses comes from considering all the kinematic
information in the event, including the missing momentum, in conjunction with
the quadratic constraints that arise from the , and mass-shell
conditions. Realistic missing momentum and lepton momenta uncertainties are
included in the analysis.Comment: 41 pages, 14 figures, various clarifications and expanded discussion
included in revised version that conforms to the version to be publishe
Trust \u3ci\u3eThe Key to Leading When Lives Are on the Line\u3c/i\u3e
The Hostage Rescue Team (HRT) of the Federal Bureau of Investigation was called in to assist the bureau\u27s Special Weapons and Tactics (SWAT) team in Memphis to apprehend a married couple wanted on drug trafficking charges. The fugitive couple and an adult son, all with criminal records, were believed to be living in trailers in a mountain valley where outsiders would be easily noticed. The fugitives were known to stockpile weapons and had vowed never to be taken alive by law enforcement. Thus the FBI considered them to be armed and extremely dangerous.
Two HRT snipers along with two SWAT snipers were given the mission of positively identifying the fugitives and providing security and containment for the assault force. The snipers would have to travel several kilometers through wooded, mountainous terrain using night vision goggles (NVGs). The SWAT snipers did not have nighttime, overland movement capability, which is why HRT was brought in
Initial determination of the spins of the gluino and squarks at LHC
In principle particle spins can be measured from their production cross
sections once their mass is approximately known. The method works in practice
because spins are quantized and cross sections depend strongly on spins. It can
be used to determine, for example, the spin of the top quark. Direct
application of this method to supersymmetric theories will have to overcome the
challenge of measuring mass at the LHC, which could require high statistics. In
this article, we propose a method of measuring the spins of the colored
superpatners by combining rate information for several channels and a set of
kinematical variables, without directly measuring their masses. We argue that
such a method could lead to an early determination of the spin of gluino and
squarks. This method can be applied to the measurement of spin of other new
physics particles and more general scenarios.Comment: 23 pages, 8 figures, minor change
The stransverse mass, MT2, in special cases
This document describes some special cases in which the stransverse mass,
MT2, may be calculated by non-iterative algorithms. The most notable special
case is that in which the visible particles and the hypothesised invisible
particles are massless -- a situation relevant to its current usage in the
Large Hadron Collider as a discovery variable, and a situation for which no
analytic answer was previously known. We also derive an expression for MT2 in
another set of new (though arguably less interesting) special cases in which
the missing transverse momentum must point parallel or anti parallel to the
visible momentum sum. In addition, we find new derivations for already known
MT2 solutions in a manner that maintains manifest contralinear boost invariance
throughout, providing new insights into old results. Along the way, we stumble
across some unexpected results and make conjectures relating to geometric forms
of M_eff and H_T and their relationship to MT2.Comment: 11 pages, no figures. v2 corrects minor typos. v3 corrects an
incorrect statement in footnote 8 and inserts a missing term in eq (3.9). v4
and v5 correct minor typos spotted by reader
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