Development of acoustically lined ejector technology for multitube jet noise suppressor nozzles by model and engine tests over a wide range of jet pressure ratios and temperatures

An experimental program comprising model nozzle and full-scale engine tests was undertaken to acquire parametric data for acoustically lined ejectors applied to primary jet noise suppression. Ejector lining design technology and acoustical scaling of lined ejector configurations were the major objectives. Ground static tests were run with a J-75 turbojet engine fitted with a 37-tube, area ratio 3.3 suppressor nozzle and two lengths of ejector shroud (L/D = 1 and 2). Seven ejector lining configurations were tested over the engine pressure ratio range of 1.40 to 2.40 with corresponding jet velocities between 305 and 610 M/sec. One-fourth scale model nozzles were tested over a pressure ratio range of 1.40 to 4.0 with jet total temperatures between ambient and 1088 K. Scaling of multielement nozzle ejector configurations was also studied using a single element of the nozzle array with identical ejector lengths and lining materials. Acoustic far field and near field data together with nozzle thrust performance and jet aerodynamic flow profiles are presented

Experimental investigation of the effects of load path on the life of fretting fatigue contacts

Slip and changes to stresses within a load cycle both contribute to damage in fretting contacts. By considering conditions for slip in normal-bulk loaded fretting contacts, experiments were performed wherein the contact slip varied, whilst changes to stress were modest. This was achieved by keeping the load endpoints constant but altering the load path. Experiments showed stark contrast in life between tests permitting slip and those prohibiting it. FE models were used to plot slip and stress components, revealing that the differences in life were due to a combination of slip and changes in shear traction. A method is presented by which the crack position can be measured, by adding a feature to the pad to produce a datum mark

Storage Device Sizing for a Hybrid Railway Traction System by Means of Bicausal Bond Graphs

In this paper, the application of bicausal bond graphs for system design in electrical engineering is emphasized. In particular, it is shown how this approach is very useful for model inversion and parameter dimensioning. To illustrate these issues, a hybrid railway traction device is considered as a case study. The synthesis of a storage device (a supercapacitor) included in this system is then discussed

The Wow Factor? A Comparative Study of the Development of Student Music Teachers' Talents in Scotland and Australia

For some time there has been debate about differing perspectives on musical gift and musical intelligence. One view is that musical gift is innate: that it is present in certain individuals from birth and that the task of the teacher is to develop the potential which is there. A second view is that musical gift is a complex concept which includes responses from individuals to different environments and communities (Howe and Sloboda, 1997). This then raises the possibility that musical excellence can be taught. We have already explored this idea with practising musicians (Stollery and McPhee, 2002). Our research has now expanded to include music teachers in formation, and, in this paper, we look at the influences in their musical development which have either 'crystallised' or 'paralysed' the musical talent which they possess. Our research has a comparative dimension, being carried out in Scotland and in Australia. We conclude that there are several key influences in the musical development of the individual, including home and community support, school opportunities and teaching styles and that there may be education and culture-specific elements to these influences

Diet patterns and dental caries in third grade U. S. children

The purpose of this study was to investigate further the relationship between intake of sucrose-containing foods and the prevalence of caries in a natural population of children. The study population was made up of 958 Caucasian third grade children from Minneapolis. Diet and brushing information was collected through personal interviews with the children. Four methods of coding diet information were used: (1) Confection Counting (the number of sucrose-containing items consumed during a 24-hour period); (2) Exposure Counting (to collapse sucrose-containing items consumed in a 30-min interval into one sucrose exposure); (3) Minneapolis Oral Retention Estimate (an assessment of usual consumption, 24-hour recall, brushing and consumption of water to estimate likelihood that the individual had sucrose in the oral cavity during a typical day); and (4) Hidden Sugar Estimate (utilization of food composition tables to estimate in teaspoons how much sucrose was consumed during a 24-hour period). The study shows few, if any, relationships existing between consumption of sucrose-containing foods and def or DMF teeth in both mealtime and between-meal periods.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72430/1/j.1600-0528.1974.tb01653.x-i1.pd

Model for the alpha and beta shear-mechanical properties of supercooled liquids and its comparison to squalane data

This paper presents data for supercooled squalane's frequency-dependent shear modulus covering frequencies from 10 mHz to 30 kHz and temperatures from 168 K to 190 K; measurements are also reported for the glass phase down to 146 K. The data reveal a strong mechanical beta process. A model is proposed for the shear response of supercooled liquids. The model is an electrical equivalent-circuit characterized by additivity of the dynamic shear compliances of the alpha and beta processes. The nontrivial parts of the alpha and beta processes are represented by a "Cole-Cole retardation element", resulting in the Cole-Cole compliance function well-known from dielectrics. The model, which assumes that the high-frequency decay of the alpha shear compliance loss varies with angular frequency as $\omega^{-1/2}$, has seven parameters. Assuming time-temperature superposition for the alpha and the beta processes separately, the number of parameters varying with temperature is reduced to four. From the temperature dependence of the best-fit model parameters the following conclusions are drawn: 1) the alpha relaxation time conforms to the shoving model; 2) the beta relaxation loss-peak frequency is almost temperature independent; 3) the alpha compliance magnitude, which in the model equals the inverse of the instantaneous shear modulus, is only weakly temperature dependent; 4) the beta compliance magnitude decreases by a factor of three upon cooling in the temperature range studied. The final part of the paper briefly presents measurements of the dynamic adiabatic bulk modulus covering frequencies from 10 mHz to 10 kHz in the temperature range 172 K to 200 K. The data are qualitatively similar to the shear data by having a significant beta process. A single-order-parameter framework is suggested to rationalize these similarities

Socioeconomic Status and Incident Type 2 Diabetes Mellitus: Data from the Women's Health Study

We prospectively examined whether socioeconomic status (SES) predicts incident type II diabetes (diabetes), a cardiovascular risk equivalent and burgeoning public health epidemic among women

Retail Price and Point of Sale Display of Tobacco in the UK: A Descriptive Study of Small Retailers

Background: Since the implementation of the 2002 Tobacco Advertising and Promotion Act, point-of-sale (PoS) tobacco displays are one of few remaining means of communication between the tobacco industry and customers in the UK. This study aimed to explore the characteristics of tobacco displays in a UK city, and particularly to assess the tobacco prices and promotional offers, types and pack sizes on display. Methods: Digital pictures of PoS displays were taken in 117 small retail shops in Nottingham in mid 2010. Data were analysed using Windows Photo Gallery software and SPSS version 16. Results: Just over half (52%) of cigarette packs on display were packs of 20, and 43 % packs of 10. Cigarette prices differed substantially between brands, ranging from £4.19 to £6.85 for 20-packs, and from £2.12 to £3.59 for 10-packs. Forty four percent of cigarette packs and 40 % of RYO (Roll-Your-Own) tobacco pouches, almost exclusively lower priced brands, were displayed with a pricemark, implying a promotional price offer. Eighty percent of 20-pack cigarette brand or brand variants on sale were priced below the EU-defined Most Popular Price Category (MPPC) for the UK in 2010; 45 % were priced below the Weighted Average Price (WAP), which replaced the MPPC in 2011. Conclusion: PoS displays communicate value by displaying a high proportion of lower cost brands, and smaller and hence lower-cost packs, and by displaying price discounts on packs. The MPPC substantially overestimated the prices at whic

Integrating Abstraction Techniques for Formal Verification of Analog Designs

The verification of analog designs is a challenging and exhaustive task that requires deep understanding of physical behaviours. In this paper, we propose a qualitative based predicate abstraction method for the verification of a class of non-linear analog circuits. In the proposed method, system equations are automatically extracted from a circuit diagram by means of a bond graph. Verification is applied based on combining techniques from constraint solving and computer algebra along with symbolic model checking. Our methodology has the advantage of avoiding exhaustive simulation normally encountered in the verification of analog designs. To this end, we have used Dymola, Hsolver, SMV and Mathematica to implement the verification flow. We illustrate the methodology on several analog examples including Colpitts and tunnel diode oscillators