Study of effects of fuel properties in turbine-powered business aircraft

Increased interest in research and technology concerning aviation turbine fuels and their properties was prompted by recent changes in the supply and demand situation of these fuels. The most obvious change is the rapid increase in fuel price. For commercial airplanes, fuel costs now approach 50 percent of the direct operating costs. In addition, there were occasional local supply disruptions and gradual shifts in delivered values of certain fuel properties. Dwindling petroleum reserves and the politically sensitive nature of the major world suppliers make the continuation of these trends likely. A summary of the principal findings, and conclusions are presented. Much of the material, especially the tables and graphs, is considered in greater detail later. The economic analysis and examination of operational considerations are described. Because some of the assumptions on which the economic analysis is founded are not easily verified, the sensitivity of the analysis to alternates for these assumptions is examined. The data base on which the analyses are founded is defined in a set of appendices

Flow control in S-Shaped Air Intake using Zero-Net-Mass-Flow

Flow control using zero-net-mass-flow jets in a twodimensional model of an S-Shaped air intake diffuser was investigated. Experiments were conducted in a channel flow facility at a Reynolds number of Re = 8×104 with particular image velocimetry measurements in the symmetry plane of the duct. In the natural configuration, separation of the boundary layer occurs in a region of the duct with a high degree of curvature. A stability analysis of the wall normal profile at the location of the applied control is presented and estimates the most effective frequency of the actuator. Time-averaged velocity fields show total reattachment of the boundary layer using active flow control

Outcome of Diode Laser Cyclophotocoagulation in Neovascular Glaucoma in Nigerians: A short-term follow-up

Aim: To find out the short-term outcome of ciliary ablation with diode laser contact cyclophotocoagulation in Nigerians with neovascular glaucoma.Methods: The study is a retrospective, non-comparative, interventional case series. Demographic data, ocular and systemic history were obtained. Clinical examination included visual acuity, intraocular pressure, number ofintraocular pressure-lowering medications and type of treatment administered at the time of NVG diagnosis. Treatment with diode laser cyclophotocoagulation was instituted. Short-term outcomes were observed and patients were followed-up for three months.Results: The study included 3 eyes of 3 patients; all above 40 years, 1 female and 2 male. At the time of NVG diagnosis, all three patients presented with severe ocular pain, and had VA between PL and NPL. Intraocular pressure on the average was 33mmHg at presentation,and associated with corneal oedema. At 3 months after initial diode laser photocoagulation (DLPC), the VA remained the same in all patients. No patient required repeat treatment. Pain reduction and lowering of theintraocular pressure were achieved at 3 months followup post-DLPC without anti-glaucoma medication. Conjunctival burns and chemosis were seen. All three eyes had corneal oedema and spontaneous hyphema by the 7 day; with subsequent s th evere corneal blood stain.Conclusions: Diode laser photocoagulation can be used as an acceptable non-invasive surgical intervention for the reduction of pain and lowering of intraocular pressure in Nigerians with neovascular glaucoma. Most shortterm complications are uneventful. The presence of hyphema with corneal oedema may enhance the occurrence of corneal blood stain in black people. The presence of corneal oedema may thus be a risk factor for corneal blood staining.Key words: short-term outcome, diode laser, corneal stainin

Modelling Molecular Motors as Folding-Unfolding Cycles

We propose a model for motor proteins based on a hierarchical Hamiltonian that we have previously introduced to describe protein folding. The proposed motor model has high efficiency and is consistent with a linear load-velocity response. The main improvement with respect to previous models is that this description suggests a connection between folding and function of allosteric proteins.Comment: 5 pages RevTeX, 2 Postscript figures, replaced due to LaTeX proble

Separation quality of a geometric ratchet

We consider an experimentally relevant model of a geometric ratchet in which particles undergo drift and diffusive motion in a two-dimensional periodic array of obstacles, and which is used for the continuous separation of particles subject to different forces. The macroscopic drift velocity and diffusion tensor are calculated by a Monte-Carlo simulation and by a master-equation approach, using the correponding microscopic quantities and the shape of the obstacles as input. We define a measure of separation quality and investigate its dependence on the applied force and the shape of the obstacles

Study of arc-jet propulsion devices Final report, 20 Nov. 1964 - 19 Dec. 1965

Energy transfer mechanisms in radiation, water, and regeneratively cooled, and MPD arc jet propulsion device

Conformational spread as a mechanism for cooperativity in the bacterial flagellar switch

The bacterial flagellar switch that controls the direction of flagellar rotation during chemotaxis has a highly cooperative response. This has previously been understood in terms of the classic two-state, concerted model of allosteric regulation. Here, we used high-resolution optical microscopy to observe switching of single motors and uncover the stochastic multistate nature of the switch. Our observations are in detailed quantitative agreement with a recent general model of allosteric cooperativity that exhibits conformational spread—the stochastic growth and shrinkage of domains of adjacent subunits sharing a particular conformational state. We expect that conformational spread will be important in explaining cooperativity in other large signaling complexes

The (C-H) bond dissociation energy in the methyl group of toluene

A, kinetic study of the pyrolysis of toluene by a flow technique has been made, and assuming Szwarc\u27s mechanism, two activation energies (78.3 and 84 kcal/mole depending on the temperature range used) have been derived for the dissociation of the (C-H) bond in the methyl group of toluene. The lower value agrees quite well with Szwarc\u27s, and the higher value turns out to be approximately the average of 77.5 and 89.9. The results of this research suggest 84 kcal/mole as the upper limit for the activation energy

Viewpoint-based testing of concurrent components

The use of multiple partial viewpoints is recommended for specification. We believe they also can be useful for devising strategies for testing. In this paper, we use Object-Z to formally specify concurrent Java components from viewpoints based on the separation of application and synchronisation concerns inherent in Java monitors. We then use the Test-Template Framework on the Object-Z viewpoints to devise a strategy for testing the components. When combining the test templates for the different viewpoints we focus on the observable behaviour of the application to systematically derive a practical testing strategy. The Producer-Consumer and Readers-Writers problems are considered as case studies

Gel-Electrophoresis and Diffusion of Ring-Shaped DNA

A model for the motion of ring-shaped DNA in a gel is introduced and studied by numerical simulations and a mean-field approximation. The ring motion is mediated by finger-shaped loops (hernias) that move in an amoeba-like fashion around the gel obstructions. This constitutes an extension of previous reptation tube treatments. It is shown that tension is essential for describing the dynamics in the presence of hernias. It is included in the model as long range interactions over stretched DNA regions. The mobility of ring-shaped DNA is found to saturate much as in the well-studied case of linear DNA. Experiments in polymer gels, however, show that the mobility drops exponentially with the DNA ring size. This is commonly attributed to dangling-ends in the gel that can impale the ring. The predictions of the present model are expected to apply to artificial 2D obstacle arrays (W.D. Volkmuth, R.H. Austin, Nature 358,600 (1992)) which have no dangling-ends. In the zero-field case an exact solution of the model steady-state is obtained, and quantities such as the average ring size are calculated. An approximate treatment of the ring dynamics is given, and the diffusion coefficient is derived. The model is also discussed in the context of spontaneous symmetry breaking in one dimension.Comment: 8 figures, LaTeX, Phys. Rev. E - in pres