Effects of vane/blade ratio and spacing on fan noise, volume 1

The noise characteristics of a high-speed fan were studied. The experimental investigation was carried out on a 50.8 cm (20 in.) diameter scale model fan stage in an anechoic chamber with an inflow turbulence control screen installed. The forty-four blade rotor was tested with forty-eight vane and eighty-six vane stator rows, over a range of aixal rotor-stator spacings from 0.5 to 2.3 rotor tip chords. A two-dimensional strip theory model of rotor-stator interaction noise was employed to predict the measured tone power level trends, and good overall agreement with measured trends was obtained

Analytical study of the effects of wind tunnel turbulence on turbofan rotor noise

The influence of tunnel turbulence on turbofan rotor noise was carried out to evaluate the effectiveness of the NASA Ames 40 by 80 foot tunnel in simulating flight levels of fan noise. A previously developed theory for predicting rotor/turbulence interaction noise was refined and extended to include first-order effects of inlet turbulence anisotropy. This theory was then verified by carrying out extensive data/theory comparisons. The resulting model computer program was then employed to carry out a parametric study of the effects of fan size, blade number, and operating line on rotor/turbulence noise for outdoor test stand. NASA Ames wind tunnel, and flight inlet turbulence conditions. A major result of this study is that although wind tunnel rotor/turbulence noise levels are not as low as flight levels they are substantially lower than the outdoor test stand levels and do not mask other sources of fan noise

High speed turboprop aeroacoustic study (counterrotation). Volume 1: Model development

The isolated counterrotating high speed turboprop noise prediction program was compared with model data taken in the GE Aircraft Engines Cell 41 anechoic facility, the Boeing Transonic Wind Tunnel, and in NASA-Lewis' 8x6 and 9x15 wind tunnels. The predictions show good agreement with measured data under both low and high speed simulated flight conditions. The installation effect model developed for single rotation, high speed turboprops was extended to include counterotation. The additional effect of mounting a pylon upstream of the forward rotor was included in the flow field modeling. A nontraditional mechanism concerning the acoustic radiation from a propeller at angle of attach was investigated. Predictions made using this approach show results that are in much closer agreement with measurement over a range of operating conditions than those obtained via traditional fluctuating force methods. The isolated rotors and installation effects models were combines into a single prediction program, results of which were compared with data taken during the flight test of the B727/UDF engine demonstrator aircraft. Satisfactory comparisons between prediction and measured data for the demonstrator airplane, together with the identification of a nontraditional radiation mechanism for propellers at angle of attack are achieved

High speed turboprop aeroacoustic study (single rotation). Volume 1: Model development

A frequency-domain noncompact-source theory for the steady loading and volume-displacement (thickness) noise of high speed propellers has been developed and programmed. Both near field and far field effects have been considered. The code utilizes blade surface pressure distributions obtained from three-dimensional nonlinear aerodynamic flow field analysis programs as input for evaluating the steady loading noise. Simplified mathematical models of the velocity fields induced at the propeller disk by nearby wing and fuselage surfaces and by angle-of-attack operation have been developed to provide estimates of the unsteady loading imposed on the propeller by these potential field type interactions. These unsteady blade loadings have been coupled to a chordwise compact propeller unsteady loading noise model to provide predictions of unsteady loading noise caused by these installation effects. Finally, an analysis to estimate the corrections to be applied to the free-field noise predictions in order to arrive at the measurable fuselage sound pressure levels has been formulated and programmed. This analysis considers the effects of fuselage surface reflection and diffraction together with surface boundary layer refraction. The steady loading and thickness model and the unsteady loading model have been verified using NASA-supplied data for the SR-2 and SR-3 model propfans. In addition, the steady loading and thickness model has been compared with data from the SR-6 model propfan. These theoretical models have been employed in the evaluation of the SR-7 powered Gulfstream aircraft in terms of noise characteristics at representative takeoff, cruise, and approach operating conditions. In all cases, agreement between theory and experiment is encouraging

Jet Noise Suppression

The objectives of this chapter are to review and summarize the jet noise suppression technology, to provide a physical and theoretical model to explain the measured jet noise suppression characteristics of different concepts, and to provide a set of guidelines for evolving jet noise suppression designs. The underlying principle for all jet noise suppression devices is to enhance rapid mixing (i.e., diffusion) of the jet plume by geometric and aerothermodynamic means. In the case of supersonic jets, the shock-cell broadband noise reduction is effectively accomplished by the elimination or mitigation of the shock-cell structure. So far, the diffusion concepts have predominantly concentrated on jet momentum and energy (kinetic and thermal) diffusion, in that order, and have yielded better noise reduction than the simple conical nozzles. A critical technology issue that needs resolution is the effect of flight on the noise suppression potential of mechanical suppressor nozzles. A more thorough investigation of this mechanism is necessary for the successful development and design of an acceptable noise suppression device for future high-speed civil transports

A Tribute to Shirley Weiss

On the evening of April 4, 1992, former colleagues and students of Shirley Weiss gathered at the Carolina Inn in Chapel Hill to pay her tribute. Part of the annual alumni weekend festivities, Shirley Weiss Day honored a woman who devoted more than thirty years of her life to city planning teaching and research, all of it at the University of North Carolina

Development of a Multi-Class Bicyclist Route Choice Model Using Revealed Preference Data

Existing regional travel forecasting systems are not typically set up to forecast usage of bicycle infrastructure and are insensitive to bicyclists\u27 route preferences in general. We collected revealed preference, GPS data on 162 bicyclists over the course of several days and coded the resulting trips to a highly detailed bicycle network model. We then use these data to estimate bicyclist route choice models. As part of this research, we developed a sophisticated choice set generation algorithm based on multiple permutations of labeled path attributes, which seems to out-perform comparable implementations of other route choice set generation algorithms. The model was formulated as a Path-Size Logit model to account for overlapping route alternatives. The estimation results show compelling intuitive elasticities for route choice attributes, including the effects of distance and delay; avoiding high-volumes of vehicular traffic, stops and turns, and elevation gain; and preferences for certain bike infrastructure types, particularly at bridge crossings and off-street paths. Estimation results also support segmentation by commute versus non-commute trip types, but are less clear when it comes to gender. The final model will be implemented as part of the regional travel forecasting system for Portland, Oregon, U.S.A

Comparision of psychometric properties of provocative clinical tests for persons with carpal tunnel syndrome - literature review

Uvod: Sindrom zapestnega prehoda je najpogostejša periferna nevropatija na zgornjem udu, pri katerem gre za utesnitev medialnega živca v predelu zapestja. V večini primerov je diagnoza postavljena že iz anamneze in pregleda pacienta, za potrditev diagnoze pa se uporabljajo tudi elektromiografske diagnostične metode in provokacijski testi. Med klinične teste spadajo Tinelov test (udarjanje po palmarni strani zapestja), karpalni kompresijski test (pritisk na medialni živec), Phalenov test (fleksija zapestja) in test dviga zgornjih udov. Med seboj se razlikujejo po psihometričnih lastnostih. Namen: s pregledom literature želimo oceniti ter primerjati psihometrične lastnosti (veljavnost, specifičnost, občutljivost) kliničnih provokacijskih testov, za oceno oseb s sindromom zapestnega prehoda. Metode dela: v diplomskem delu smo uporabili deskriptivno metodo s sistematičnim pregledom literature. Pri izdelavi diplomske naloge so bile za iskanje literature oz. člankov uporabljene podatkovne zbirke PubMed, Researchegate, Springeropen, Cobiss in brskalnik Google Scholar. Iskanje je bilo omejeno na rendomizirane kontrolirane poskuse v slovenskem ali angleškem jeziku, prosto dosegljive celotne članke. Iskanje ni bilo omejeno na določeno časovno obdobje objave virov. Rezultati: v začetni fazi diagnosticiranja sindroma zapestnega prehoda je ključna dobra anamneza ter klinična slika pacienta. Za stopnjo utesnitve medianega živca se priporoča uporaba elektromiografskih diagnostičnih metod, v kombinaciji s kliničnimi provokacijskimi testi. Pregled literature je pokazal, da je test dviga zgornjih udov bolj občutljiv in specifičen provokativni test (s 86,6 % specifičnostjo in 89,5 % občutljivostjo) kot Phalenov in Tinelov test. Karpalni kompresijski test ima podobno občutljivost in specifičnost kot test dviga zgornjih udov, hkrati pa je tudi najbolj veljaven test (z 89,8 % veljavnostjo). Razprava in zaključek: Phalenov in Tinelov test sta označena za najbolj uporabljena testa za klinično oceno pacientov s sindromom zapestnega prehoda, vendar veljata za srednje občutljiva, specifična ter veljavna provokacijska testa. Prihodnje študije bi morale hkrati primerjati vse štiri klinične provokacijske teste na isti skupini preiskovancev.Carpal tunnel syndrome is the most common peripheral neuropathy of the upper limb, caused by compression of the medial nerve at the wrist. The diagnosis can be set from medical history and clinical patient’s examination in most cases, which can be further confirmed with electromyographic diagnostic methods and provocative tests. These clinical tests are Tinel\u27s test (tapping on the palmar side of the wrist), carpal compression test (pressure on the medical nerve), Phalen\u27s test (wrist flexion) and hand elevation test, which all have different psychometrical characteristics. Purpose: To review literature on psychometrical characteristics (validity, specificity, sensitivity) of the clinical provocative tests for detecting carpal tunnel syndrome. Methods: In this degree paper we used a descriptive method with a systematic review of scientific literature. Articles were searched in PubMed, Researchgate, Google schooler, Springeropen and Cobiss databases. The search was limited to randomized controlled studies in both Slovenian and English language, freely accessible in full text. The search was not limited on a specific time frame. Results: Well established anamnesis and clinical examination of the patient are key for successful diagnostics in the early phase of the carpal tunnel syndrome. For establishing degree of medial nerve compression, it is recommended to use electrodiagnostic methods combined with clinical provocative tests. He literature review has shown that hand elevation test is more sensitive and specific provocative test (with 86,63% specific and 89,53% sensitive) than Phalen\u27s and Tinel\u27s tests. The carpal compression test has similar sensitivity and specificity than hand elevation test, while it is also the most valid test (with 89,77% validity). Discussion and conclusion: Although the Phalen\u27s and Tinel\u27s tests are the most frequently used for patients with carpal tunnel syndrome, they are not the most sensitive, specific and valid provocative tests available. Future studies should simultaneously compare all four clinical tests on the same patient samples

High speed turboprop aeroacoustic study (counterrotation). Volume 2: Computer programs

The isolated counterrotating high speed turboprop noise prediction program developed and funded by GE Aircraft Engines was compared with model data taken in the GE Aircraft Engines Cell 41 anechoic facility, the Boeing Transonic Wind Tunnel, and in the NASA-Lewis 8 x 6 and 9 x 15 wind tunnels. The predictions show good agreement with measured data under both low and high speed simulated flight conditions. The installation effect model developed for single rotation, high speed turboprops was extended to include counter rotation. The additional effect of mounting a pylon upstream of the forward rotor was included in the flow field modeling. A nontraditional mechanism concerning the acoustic radiation from a propeller at angle of attack was investigated. Predictions made using this approach show results that are in much closer agreement with measurement over a range of operating conditions than those obtained via traditional fluctuating force methods. The isolated rotors and installation effects models were combined into a single prediction program. The results were compared with data taken during the flight test of the B727/UDF (trademark) engine demonstrator aircraft

Research and Development of a Land Use Scenario Modeling Tool

Oregon Department of Transportation’s (ODOT) Transportation Planning and Analysis Unit (TPAU) developed a land use modeling tool called the “Land Use Scenario Developer in R” (LUSDR). LUSDR is a modeling tool, written in the “R” language, that may be used to predict and analyze regional land use changes probabilistically, creating a distribution of possible outcomes. It is designed to be integrated with travel demand modeling programs, making it potentially valuable for analyzing the interaction between transportation and land use when assessing various growth-policy and socioeconomic assumptions. This project is Phase 2 for Research and Development of a Land Use Scenario Modeling Tool. It is intended to address several extant deficiencies in the LUSDR modeling tool, each identified below, as a separate research task. The original proposed outcomes of this research were a set of programs, data, and documentation that would comprise a deployable LUSDR package