Aircraft wing trailing-edge noise

The mechanism and sound pressure level of the trailing-edge noise for two-dimensional turbulent boundary layer flow was examined. Experiment is compared with current theory. A NACA 0012 airfoil of 0.61 m chord and 0.46 m span was immersed in the laminar flow of a low turbulence open jet. A 2.54 cm width roughness strip was placed at 15 percent chord from the leading edge on both sides of the airfoil as a boundary layer trip so that two separate but statistically equivalent turbulent boundary layers were formed. Tests were performed with several trailing-edge geometries with the upstream velocity U sub infinity ranging from a value of 30.9 m/s up to 73.4 m/s. Properties of the boundary layer for the airfoil and pressure fluctuations in the vicinity of the trailing-edge were examined. A scattered pressure field due to the presence of the trailing-edge was observed and is suggested as a possible sound producing mechanism for the trailing-edge noise

Evidence of late Quaternary environmental change in a continental east Antarctic lake from lacustrine sedimentary pigment distributions

A sediment core from Progress Lake, one of the oldest lacustrine sequences in East Antarctica, contains distinct zones dating from a previous interglacial (most likely Marine Isotope Stage 5e, c. 125-115 kyr BP) and the present interglacial (Marine Isotope Stage 1), separated by a transition zone representing when the lake became sub-glacial. Profiles of fossil pigments, determined using high performance liquid chromatography and liquid chromatography-tandem mass spectrometry, show distinct differences in the photoautotrophic community during these two interglacial periods. The first was dominated by algae and purple phototrophic bacteria, with periods of photic zone euxinia indicated by pigments from anoxygenic phototrophic bacteria. Specific chlorophyll a derivatives reveal periods when grazing pressure impacted significantly on the phytoplankton community. The virtual absence of pigments in the transition zone reflects severe restriction of photoautotrophic activity, consistent with the take having become sub-glacial. Retreat of snow and ice in the late Holocene (3345 C-14 yr Bp) allowed establishment of a less diverse primary producer community, restricted to algae and cyanobacteria. Grazers were severely restricted and oxidative transformation was more important than during the previous interglacial. The pigment data provide a unique and detailed insight in to the evolution of the lake ecology over an interglacial-glacial-interglacial transition and strong evidence that the Marine Isotope Stage 5e interglacial in this region of coastal East Antarctica was several degrees warmer than at present

Personality disorder in primary care : factors associated with therapy process and outcome.

Assessment and treatment of personality disorder (PD) is a key issue in UK mental health service provision (NIMH report, 2003), but there is limited information on individuals with personality disorder presenting to primary care mental health services. This study investigates the characteristics of PD in individuals receiving cognitive behaviour therapy (CBT) following GP referral and its relationship with therapist ratings of treatment process and outcome. One hundred and forty-eight participants completed the Millon Multiaxial Clinical Inventory (MCMI-III: Millon, Davis and Millon, 1997). Therapists completed a measure of therapy process and outcome (TPOQ) on 100 participants. Key therapy and process questions were answered for 60 participants who attended a minimum of five therapy sessions. MCMI-III indicated a rate of PD of 56.4%. Factor analysis of PD scales identified two factors: inward looking/emotionally distanced, and aggressive/acting out. For clinical syndromes (CLS), the factors were general psychopathology and substance abuse. TPOQ had two factors: therapeutic alliance and complexity in therapy. Regression analyses indicated that only those PDs contributing to the inward looking/emotionally distanced scale score were associated with therapeutic alliance problems. Conversely, complexity in therapy was only predicted by general psychopathology and not by personality disorder. This study identified high rates of personality disorder in primary care referrals to a clinical psychology service. It also indicated that relationships between the presence of personality disorder and therapist ratings of treatment difficulties were only associated with certain types of personality disorder. These findings are discussed in relation to service and therapy planning in mental health

The static, dynamic and metadynamic recrystallisation of a medium carbon steel

Grain refinement during and after hot isothermal deformation of a medium carbon steel has been investigated. The average austenite grain size decreased with an increase in strain for the hot deformed and recrystallised material, with refinement extending beyond the strain for the peak stress. A window of strain that corresponds to transition from classical static to metadynamic recrystallisation was observed in respect to the recrystallised material. Within this post-dynamic transition window the strain at which strain independent softening occurs was different for different volume fractions of the recrystallised material. This led to a new terminology corresponding to initiation of strain independent softening. For the alloy of this study, strain independent softening for the start of post-deformation recrystallisation occurred near the strain to the peak stress. The strain corresponding to complete metadynamic recrystallisation, which was defined as when all levels of recrystallisation were strain independent, was much greater than the strain for the peak stress. <br /

The Philosophical Relations of Neurology

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Resonance Patterns in a Stadium-shaped Microcavity

We investigate resonance patterns in a stadium-shaped microcavity around $n_ck R \simeq 10$, where $n_c$ is the refractive index, $k$ the vacuum wavenumber, and $R$ the radius of the circular part of the cavity. We find that the patterns of high $Q$ resonances can be classified, even though the classical dynamics of the stadium system is chaotic. The patterns of the high $Q$ resonances are consistent with the ray dynamical consideration, and appears as the stationary lasing modes with low pumping rate in the nonlinear dynamical model. All resonance patterns are presented in a finite range of $kR$.Comment: 8 pages, 9 figure

Tests of a single phase induction motor

Citation: Hodgson, Frederick Earl and Johnson, James H. Tests of a single phase induction motor. Senior thesis, Kansas State Agricultural College, 1905.Morse Department of Special CollectionsIntroduction: With the growing electrical industry there is an increasing demand for convenient, efficient and practical mans of utilizing electrical energy. The combined efforts of the designer and manufacturer have produced an electric motor to suit the various demands made upon it. The direct current and synchronous motors still hold their respective places in the conversion of electrical into mechanical energy. While these motors hold a place which, perhaps no other motor can hold, they are at the same time found unsatisfactory in many modern requirements. The question might justly be asked why these motors do not fill all the requirements of an electric motor, why is the induction motor coming into use and what are its advantages? Probably a strong point in favor of the induction motor is its adaptability to the present use of alternating current; however the synchronous motor with its characteristic faults also holds a place in this field. The shunt and series motor might also be used on alternating current; however the shunt motor has the objection that in the armature the current is in phase with the E.M.F. while the high inductance in the fields gives the current- in them about 90 degrees lag, thus throwing the armature current and field current out of phase with each other. To overcome this objection the field may be excited from a separate E.M.F. differing in phases 90 degrees from that supplied to the armature. A quarter phase machine would do this, one phase furnishing current for the armature while the other supplied the field, but this would load the two phase