The effects of site selected variables on human responses to traffic noise,part III: Community size by socio-economic status by traffic noise level

This paper reports the results of the third part of a field study of human responses to traffic noise. The influence of traffic noise level, community size, and socio-economic status were investigated in a controlled manner determined by subject selection procedures. Human responses were obtained from interviewer administered questionnaires, and were as spatially and temporally coincident with the noise measurements as possible. Noise measurements were obtained from several days of rapidly sampled digital recordings. Traffic noise level was the major predictor of the intensity of elicited responses. A number of other significant effects were observed largely related to community size. These were explained as due to parallel variations in the perceived necessity of vehicles, the annoyance with aircraft noise, and the logarithm of the vehicle flow rate. The results did demonstrate effects related to community size, and thus it is unwise to extrapolate the results of large city noise studies to small communities and rural areas.     

Megawatt VUV xenon laser employing coaxial electron-beam excitation

3 nsec laser pulses, of bandwidth 1.3 nm, are obtained from a 10 J, 600 keV coaxial diode electron-beam pumping arrangement. Uniform pumping, with a well defined cylindrical geometry, facilitates experimental investigation of the laser parameters. Gas heating limits the laser repetition rate. While mirror damage at present limits the peak power to ∽ 1 MW, higher powers seem available. The addition of helium results in a drastic reduction of peak molecular xenon fluorescence.     

Nuclear orientation below 1 mK: Development and applications

The Oxford top-loading PrNi₅ nuclear demagnetisation stage /1/ has been further developed to reach temperatures below 1 mK. The hyperfine field for⁷¹As in nickel has been measured by low temperature nuclear orientation as 14.61(36)T. Measurements on transitions in⁷¹Ge yield spin values 3/2 (1299 kev and 1139 kev) and 5/2 (1027 kev) and 5 E2/M1 mixing ratios are given.     

Detection of heteroplasmy in individual mitochondrial particles

Mitochondrial DNA (mtDNA) mutations have been associated with disease and aging. Since each cell has thousands of mtDNA copies, clustered into nucleoids of five to ten mtDNA molecules each, determining the effects of a given mtDNA mutation and their connection with disease phenotype is not straightforward. It has been postulated that heteroplasmy (coexistence of mutated and wild-type DNA) follows simple probability rules dictated by the random distribution of mtDNA molecules at the nucleoid level. This model has been used to explain how mutation levels correlate with the onset of disease phenotype and loss of cellular function. Nonetheless, experimental evidence of heteroplasmy at the nucleoid level is scarce. Here, we report a new method to determine heteroplasmy of individual mitochondrial particles containing one or more nucleoids. The method uses capillary cytometry with laser-induced fluorescence detection to detect individual mitochondrial particles stained with PicoGreen, which makes it possible to quantify the mtDNA copy number of each particle. After detection, one or more particles are collected into polymerase chain reaction (PCR) wells and then subjected to real-time multiplexed PCR amplification. This PCR strategy is suitable to obtain the relative abundance of mutated and wild-type mtDNA. The results obtained here indicate that individual mitochondrial particles and nucleoids contained within these particles are not heteroplasmic. The results presented here suggest that current models of mtDNA segregation and distribution (i.e., heteroplasmic nucleoids) need further consideration.     

Acoustic streaming field structure. Part II. Examples that include boundary-driven flow

In this paper three simple acoustic streaming problems are presented and solved. The purpose of the paper is to demonstrate the use of a previously published streaming model by Bradley [J. Acoust. Soc. Am. 100(3), 1399-1408 (1996)] and illustrate, with concrete examples, some of the features of streaming flows that were predicted by the general model. In particular, the problems are intended to demonstrate cases in which the streaming field boundary condition at the face of the radiator has a nontrivial lateral dc velocity component. Such a boundary condition drives a steady solenoidal flow just like a laterally translating boundary drives Couette flow.     

The Problems of the Turbulent Burning Velocity

The paper reviews the practical problems in measuring a turbulent burning velocity that gives the mass rate of burning. These largely centre on identifying an appropriate flame surface to associate with the turbulent burning velocity, u _t , and the density of the unburned mixture. Such a flame surface has been identified, in terms of the mean reaction progress variable, $\bar {c}$ , for explosive flame propagation in a fan-stirred bomb. Measurement of $\bar {c}$ makes possible an estimation of the flame surface density, ??, from the relationship ${\it \Sigma} =k\bar {c}\left( {1-\bar {c}} \right)$ . It is shown that in such explosions, mass rates of burning derived from the measured total flame surface area agreed well with those found from the measured turbulent burning velocity. Flamelet considerations identify appropriate dimensionless correlating parameters for u _t . As a result, correlations of turbulent burning velocity divided by the effective rms turbulent velocity, are plotted against the turbulent Karlovitz stretch factor, K, for different values of the Markstein number for flame strain rate, Ma_sr. These plots cover a wide range of variables, including pressure and fuels, and are indicative of different regimes of turbulent combustion. At the lower values of K, there is some evidence of increases in u _t and k due to high-frequency flame surface wrinkling arising from flame instabilities. These increase as Ma_sr becomes more negative. It is found from the developed value of the mean flame surface density throughout the flame brush that, to a first approximation, an increase in u _t for a given mixture is accompanied by a proportional increase in the volume of the brush. The analysis shows that the volume fraction of the turbulent flame brush that is reacting is quite small.     

Detection of incipient gear failures using statistical techniques

Gears are important components in most power transmission mechanisms.Failures of gears can cause heavy losses in industry. Conditionmonitoring and fault diagnosis of gears is therefore importantto improve safety and reliability of gearbox operations andreduce losses caused by gear failures. This research proposesa new diagnostic approach based on the statistical analysisof data. It investigates the use of Principal Components Analysis(PCA) to detect growing local faults in a two-stage industrialhelical gearbox. In this research, the vibration signal is usedto monitor fault conditions and a broken tooth is simulatedas a local fault. Since the early detection of faults is a challenge,small fault conditions were tested first as well as severe faultconditions. In order to examine the ability of the PCA to detectfault conditions, first the PCA-based model was created fornormal operating conditions. Any unexpected event such as afault condition causes a significant deviation from the PCAmodel, which is obtained from the normal condition data of thegearbox. The Square Prediction Error (SPE) was calculated todetect the fault conditions. When the vibration signal fromthe gearbox is representative of normal operation, the valueof the SPE shows very little fluctuation and remains under acertain threshold value. However, in the presence of the faultthe SPE fluctuates considerably beyond the threshold value.It is shown that the PCA-based statistical approach cannot onlybe used to detect severe fault conditions, but that it alsoreveals small growing fault conditions at very early stage.The technique also provides information about the state of thefault such as the location of the fault as well as its severity. Received 5 March 2001. Revised 12 December 2001. Accepted 17 January 2002.     

On Quantiles and the Central Limit Question for Strongly Mixing Sequences

Three classes of strictly stationary, strongly mixing random sequences are constructed, in order to provide further information on the borderline of the central limit theorem for strictly stationary, strongly mixing random sequences. In these constructions, a key role is played by quantiles, as in a related construction of Doukhan et al.⁽¹¹⁾     

A conservative formulation for plasticity

In this paper we propose a fully conservative form for the continuum equations governing rate-dependent and rate-independent plastic flow in metals. The conservation laws are valid for discontinuous as well as smooth solutions. In the rate-dependent case, the evolution equations are in divergence form, with the plastic strain being passively convected and augmented by source terms. In the rate-independent case, the conservation laws involve a Lagrange multiplier that is determined by a set of constraints; we show that Riemann problems for this system admit scale-invariant solutions.