On the fractal characteristics of low Damköhler number flames

Knowledge of the fractal properties of premixed flame surfaces can potentially be used to help develop turbulent combustion models. Here, direct numerical simulations of low Damköhler number flames are used to analyse the fractal nature of the flames. Two sets of data are considered: (i) thermochemical hydrogen–air turbulent premixed plane-jet flames with detailed chemistry and (ii) thermonuclear flames in type Ia supernovae. A three-dimensional box counting method is used to investigate fractal dimension of the flame surface, characterising the self similarity of flame fronts. In the premixed flames, the fractal dimension is found to vary in time between 2.1 and 2.7. The supernovae flames in distributed combustion regimes yield fractal dimension about 2.7. The results for the maximum fractal dimensions are higher than previously reported. They are explained theoretically by a Reynolds number similarity argument which posits that the high Reynolds number, low Damköhler number limiting value of the fractal dimension is 8/3. Also tested is Mandelbrot’s fractal additive law which relates the fractal dimension determined in two dimensions, which is typical of experimental measurements, to that in three dimensions. The comparison of the fractal dimension in both two-dimensional and three-dimensional spaces supports the additive law, even though the flames considered do not formally satisfy isotropy. Finally, the inner-cut off is extracted from the hydrogen flames and found to be consistent in order of magnitude with Kolmogorov scaling.     

Modeling the effects of hypoglycemia on a two-choice task in adult humans.

Objective: Previous research has demonstrated that hypoglycemia causes reaction times to be slower and more variable. Reaction time tests, however, use multiple cognitive and noncognitive processes. This study is the first to use a validated sequential sampling model (diffusion model) applied to results obtained from a simple 2-choice task in adult humans to assess the effects of hypoglycemia on the basic parameters of decision making. Method: Fourteen adult volunteers were tested on a numerosity discrimination task with and without reduced blood glucose concentrations. The results were analyzed with a model that dissects the components of processing that underlie decisions: the quality of the information on which a decision is based (drift rate), the critical amount of evidence that must be accumulated before a decision is made (boundary separation), and the time taken by nondecision processes. Results: Hypoglycemia resulted in a reduction of mean drift rate from 0.290 to 0.211, t(13) = 4.10, p     

A best practice process model for hybrid concrete construction

The term ‘hybrid concrete construction’ (HCC) is used to describe the combination of concrete construction methods, e.g. in‐situ concrete and precast concrete, with one another or with other materials, e.g. steel. Although it could be argued that most buildings employ such combinations, HCC is the deliberate integration of different construction techniques to achieve a cost, speed or other performance benefit. UK government has been concerned that the construction industry suffers from poor management and exchange of tacit knowledge which can disappear after project teams ‘break up’. The completion of several innovative and high profile HCC projects was considered to be a major opportunity to capture project teams' tacit knowledge in this area. The objective of the research was to compile a best practice process model, such that project teams could be better informed as to their roles and responsibilities and thus be better equipped to deliver a building to the client's satisfaction, by using HCC. Interviews and knowledge capture workshops were used to extract lessons that lay embedded in both individuals and teams. The main conclusions were that successful HCC projects were characterized for example, by the development of an ethos of trust, the early involvement of specialists (such as precasters) and the effective management of both tacit and explicit knowledge. The research builds on previous work in the area by identifying best practice information on design, specification and construction factors for HCC and, in addition, some transferable lessons on knowledge capture techniques.     

Effect of dietary n−3 and n−6 polyunsaturated fatty acids on lipid-metabolizing enzymes in obese rat liver

This study was designed to examine whether n−3 and n−6 polyunsaturated fatty acids at a very low dietary level (about 0.2%) would alter liver activities in respect to fatty acid oxidation. Obese Zucker rats were used because of their low level of fatty acid oxidation, which would make increases easier to detect. Zucker rats were fed diets containing different oil mixtures (5%, w/w) with the same ratio of n−6/n−3 fatty acids supplied either as fish oil or arachidonic acid concentrate. Decreased hepatic triacylglycerol levels were observed only with the diet containing fish oil. In mitochondrial outer membranes, which support carnitine palmitoyltransferase I activity, cholesterol content was similar for all diets, while the percentage of 22∶6n−3 and 20∶4n−6 in phospholipids was enhanced about by 6 and 3% with the diets containing fish oil and arachidonic acid, respectively. With the fish oil diet, the only difference found in activities related to fatty acid oxidation was the lower sensitivity of carnitine palmitoyltransferase I to malonyl-CoA inhibition. With the diet containing arachidonic acid, peroxisomal fatty acid oxidation and carnitine palmitoyltransferase I activity were markedly depressed. Compared with the control diet, the diets enriched in fish oil and in arachidonic acid gave rise to a higher specific activity of aryl-ester hydrolase in microsomal fractions. We suggest that slight changes in composition of n−3 or n−6 polyunsaturated fatty acids in mitochondrial outer membranes may alter carnitine palmitoyltransferase I activity.     

Automatic annotation of tennis games: An integration of audio,vision, and learning

Fully automatic annotation of tennis game using broadcast video is a task with a great potential but with enormous challenges. In this paper we describe our approach to this task, which integrates computer vision, machine listening, and machine learning. At the low level processing, we improve upon our previously proposed state-of-the-art tennis ball tracking algorithm and employ audio signal processing techniques to detect key events and construct features for classifying the events. At high level analysis, we model event classification as a sequence labelling problem, and investigate four machine learning techniques using simulated event sequences. Finally, we evaluate our proposed approach on three real world tennis games, and discuss the interplay between audio, vision and learning. To the best of our knowledge, our system is the only one that can annotate tennis game at such a detailed level.     

Supercritical solvents. Carbon dioxide extraction of retained pyridine from pyridine extracts of coal

Pyridine extracts of coal are excellent models for studies of coal structure and reactions, but the pyridine that is retained is undesirable. A method is described, using supercritical carbon dioxide, for the removal of retained pyridine from pyridine extracts of Illinois No. 6 and Western Kentucky No. 9 coals.     

A silent shift? The precarisation of the Dutch rental housing market

The traditional Dutch rental contract is permanent (i.e. time unlimited), but there are indications that in recent years the number of temporary rental contracts has increased considerably. Dutch housing policy appears to be responding to this by pursuing deregulation of the conditions under which temporary rent is permitted. It is in this regard startling that there is no reliable data available about the size or character of the temporary sector, and it has thus far not attracted any scholarly attention. Given that temporary rent can be viewed as a form of precarisation, a transfer of risk to citizens, with corresponding negative effects on the lives of those involved, it is imperative to close this knowledge gap. This paper is a first attempt to do this. Firstly, I systematically review the scarce evidence that is currently available, and secondly, I explore why the rise of temporary rent has thus far failed to stimulate any social debate; it appears to constitute a silent precarisation that contrasts with the politically sensitive issue of labour precarisation. In doing so, I will identify the research questions that must be answered if the significance of this process for both tenants and wider welfare-state restructuring is to be fully understood.     

Comportement des acides amines dissous du milieu marin apres injection de chlore

Evidence that dissolved organic matter is one of the most significant sources of chlorine demand of seawaters (Fig. 1) used in cooling circuits is now well recognized. Nevertheless the specific role of the different kinds of compounds which form this organic material has seldom been studied and even less quantified; this is not surprising as less than 20% of the organic substances are identified. In this paper our objective was to define more quantitatively the effect of the dissolved free and combined amino-acids in the oxidant decay. Two main criteria justified the choice of these solutes:

1. (i)|the reactivity of chlorine and/or bromine towards amino groups;

2. (ii)|the role of these nitrogenous compounds in some biological mechanisms.

What happens to the halogen added and to the organic species during the first 20 min was investigated. The experimental conditions selected (concentrations, salinity, temperature and acidity) are those encountered in practice.The reactivity of the amino-acids towards chlorine is of course influenced by physicochemical properties such as the pH, but is particularly dependent upon the nature of the amino group. Whereas β and γ free amino-acids (Fig. 3) as also combined species (proteins) (Table 2) yield stable halogenocompounds like those produced with aliphatic amines (Fig. 2), α free amino-acids (COOH---CH---NH₂)|R on the other hand yield unstable haloamines which decompose rapidly (Fig. 4). Regarding these results, only the reactivity of the α compounds was afterwards studied as they are the largest fraction of the free amino-acids encountered in natural waters.After investigating the role of the side groups R in the kinetics and the efficiency of the consumption of the oxidant we examined, by liquid chromatography, the depletion of the nitrogenous species (Table 3). In each case the HPLC data relative to changes in the level of the organic compounds agree with those reported for the residual oxidant decay.A few experiments carried out on samples of seawater (Table 4) treated with 1 ppm of chlorine showed that around 5% of chlorine which dissipated during the first 3 min are consumed by the dissolved free amino-acids, the depletion of which is about 50%.     

西洋参原材料近红外光谱精选研究

为确保药物成品质量的稳定均一,作为原材料的西洋参应保证纯正。采用近红外积分球漫反射光谱,首先对西洋参、人参原样光谱运用移动窗口偏最小二乘法(moving window partial least-squares regression,MWPLS)选择特征波段,建立最小二乘支持向量机(least-squares support vector machine,LS-SVM)种类鉴别模型挑选出西洋参样品,判别正确率为100%。然后将样品粉碎,人参以5%、10%、15%、20%掺入西洋参粉末,为增加样品代表性借助线性加和模拟光谱手段于4 000～7 000 cm-1建立主成分判别分析(principal component analysis discriminant analysis,PCA-DA)掺杂判别模型,预测判别正确率由97.2%上升至100%,区分出少量人参掺杂的西洋参样品,最终精选出西洋参原材料纯品。