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Traditional Ghanaian furniture designs are known as an exhibition of the splendor and elegance of decorative objects or decorative ornaments that carry profound philosophical and sacred meanings. The features found in Ghana’s traditional Ghanaian design can be considered as objects for international players, with their own identity and not found elsewhere. This paper therefore seeks to identify and illuminate some of these Akan cultural objects in Ghana by referring to the Ashanti region. This paper also shows with examples how these design elements can be developed and maintained by integrating them into modern furniture and interior designs or as a straightforward or adaptive design.

European regulations state a minimum boiler efficiency for the main steady-state functioning conditions and for the overall heating season conditions. In order to comply the demands of the new regulations, more and more boiler manufacturers are switching the gas boilers production to condensing functioning. In the paper we present the numerical and computational modeling of a boiler made out of packages of finned tubes and packages of smooth pipes. Validation of the computational results is made by comparison with experimental results obtained in a certified laboratory for the modelled equipment (boiler). The modelling was set on an aluminium finned tubes heat exchanger existent in the testing laboratory (part of a condensing boiler). The geometry modeling considered the discretization of the heat exchanger in several zones, characterized by homogenous flue gas flow speed, flow geometry and heat transfer characteristics (mainly feature-length). A good correlation between measured and calculated values was obtained, the error ranging +/- 1% for the total and sensible heat and for thermal efficiency.

In this paper we present an automatic control system for stage lights that can be used for small events. The system has two main functions: it can perform a generic light show that corresponds to a specific music type like jazz, pop or rock, or it can adapt to the music performed on stage by the artist. The system uses an Arduino Mega for processing the collected data from a MEMS microphone breakout board and a specialized graphic equalizer chip and for controlling the LED lights.The system is designed to be in the low cost range so an independent or debutant artist can acquire it.

The conical tunnel burner is an improvement of the cylindrical tunnel burner because, by maintaining all its advantages by means of burning intensification, it may also insure the flame stabilization in a wide range of regulation with considerable diminished pressure losses. Technical applications for the conical furnace burner can vary due to the limited dimensions required by the system, as well as the important thermal loads, and also because of the burning stability characteristic that spreads over an important range of regulation. The low costs required by the burner, generated mainly by its simple construction, also raise the interest for this technical solution. A physical model is proposed for the ignition and flame front stabilization. The flame front stabilization contains different steps from the ignition moment to final flame front stabilization, with specific flame front geometries and specific locations along the burner axis. The installation realised by the authors allowed the experimental study of the burning process in conical furnaces, in order to determine the temperature fields and the flame profiles. The physical model developed for this new type of application and the experimental data sets obtained (along with their interpretation) make the subject of this paper.

For technical applications, a physical model capable of predicting the particle evolution in the burning process along its trajectory through the furnace is very useful. There are two major demands: all the thermo-dynamic processes that describe the particle burning process must be accounted and the model must be written in such equation terms to allow the intervention for parameter settings and particle definition. The computations were performed for the following parameters: furnace average temperature between 700 and 1200 °C, size of the sawdust particle from 4 to 6 mm and fix carbon ignition between 500 and 900 °C. The values obtained for the characteristic parameters of the burning process ranged from 30 to 60 [kg/(h·m3)] for the gravimetrical burning speed WGh and from 150 to 280 [kW/m3] for the volumetric thermal load of the furnace QV. The main conclusion was that the calculus results are in good agreement with the experimental data from the pilot installations and the real-case measurements in the sawdust working boiler furnaces or pre-burning chambers. Another very important conclusion is that the process speed variation, when the furnace temperature changes, confirms the thermo-kinetic predictions, namely that the burning process speed decreases when the furnace temperature increases.

When modelling biological processes, there are always errors, uncertainties and variations present. In this paper, we consider the coefficients in the mathematical model to be random variables, whose distribution and moments are unknown a priori, and need to be determined by comparison with experimental data. A stochastic spectral representation of the parameters and the solution stochastic process is used, based on polynomial chaoses. The polynomial chaos representation generates a system of equations of the same type as the original model. The inverse problem of finding the parameters is reduced to establishing the best-fit values of the random variables that represent them, and this is done using maximum likelihood estimation. In particular, in modelling biofilm growth, there are variations, measurement errors and uncertainties in the processes. The biofilm growth model is given by a parabolic differential equation, so the polynomial chaos formulation generates a system of partial differential equation...

Biofilms are colonies of bacteria that attach to surfaces by producing extracellular polymer substances. They may cause serious infections in humans and animals, and also cause problems in hydraulic machinery. In this paper we model the growth of a biofilm established on a medical implant. We assume that the biofilm's growth is given by a logistic reaction term with the growth rate being a random variable with a given distribution. This way we take into account the variability in the bacterial populations, and the measurement and experimental errors. The diffusion coefficient of the microbes is also taken to be random. A stochastic spectral representation of the parameters and the unknown stochastic process is used, together with the polynomial chaos method, to obtain a system of partial differential equations, which is integrated numerically to obtain the evolution of the mean and higher-order moments with respect to time. Some examples are presented.

Mathematical models are very important in epidemiology. Many of the models are given by differential equations and most consider that the parameters are deterministic variables. But in practice, these parameters have large variability that depends on the measurement method and its inherent error, on differences in the actual population sample size used, as well as other factors that are difficult to account for. In this paper the parameters that appear in SIR and SIRS epidemic model are considered random variables with specified distributions. A stochastic spectral representation of the parameters is used, together with the polynomial chaos method, to obtain a system of differential equations, which is integrated numerically to obtain the evolution of the mean and higher-order moments with respect to time.

Implicit methods are the natural choice for solving stiff systems of ODEs. Rosenbrock methods are a class of linear implicit methods for solving such stiff systems of ODEs. In the Rosenbrock methods the exact Jacobian must be evaluated at every step. These evaluations can make the computations costly. By contrast, W-methods use occasional calculations of the Jacobian matrix. This makes the W-methods popular among the class of linear implicit methods for numerical solution of stiff ODEs. However, the design of high-order W-methods is not easy, because as the order of the W-methods increases, the number of order conditions of the W-methods increases very fast. In this paper, we describe an approach to constructing high-order W-methods.

This paper studies round jet with large eddy simulation (LES) method, in which spectral element technique is used as spacial discritization for the large eddy simulation Navier–Stokes equations. A local spectral discretization associated with Legendre polynomials is employed on each element of the structured mesh, which allows for high accurate simulations of turbulent flows. Discontinuities across the interfaces of the elements are resolved using a Riemann solver. An isoparametric representation of the geometry is implemented, with boundaries of the domain discretized to the same order of accuracy as the solution, and explicit low-storage Runge–Kutta methods are used for time integration. LES results of round jet are presented, in which the instantaneous and statistical turbulence structures of the round jet have been captured. The probability density function, and the spectral density function of the round jet that can reflect properties of turbulence have also been estimated. The work serves the purpose of allowing fast, convenient computations and comparisons with theoretical results and the ultimate goal is to develop it into an LES code featuring spectral accuracy with minimum dissipation and dispersion, a valuable tool for round jet computations.

characteristic length and time scales of inflowing turbulent eddies are consistent with the corresponding Reynoldsaveraged Navier–Stokes profiles imposed at the inlet. The resulting large-eddy simulation method is validated against experimental data of both swirling and nonswirling turbulent jets. The application of the validated largeeddy simulation method to studies of the mechanism of swirl effects shows the following. Swirl breaks apart the typicalringstructuresofnonswirlingturbulentjetsintotwomodes:ahelicalmodeandstreamwisebraidstructures. The interaction of these two modes generates unorganized turbulence that enhances the turbulent mixing. An analysis of the mixing enhancement byswirl shows asignificantincrease of the turbulent mixing efficiency of scalars with the swirl number (of up to 21.7% for the cases considered).

In the mathematical modeling of population growth, and in particular of bacterial growth, parameters are either measured directly or determined by curve fitting. These parameters have large variability that depends on the experimental method and its inherent error, on differences in the actual population sample size used, as well as other factors that are difficult to account for. In this work the parameters that appear in the Monod kinetics growth model are considered random variables with specified distributions. A stochastic spectral representation of the parameters is used, together with the polynomial chaos method, to obtain a system of differential equations, which is integrated numerically to obtain the evolution of the mean and higher-order moments with respect to time.

A study of boundary and interface conditions for Discontinuous Galerkin approximations of fluid flow equations is undertaken in this paper. While the interface flux for the inviscid case is usually computed by approximate Riemann solvers, most discretizations of the Navier-Stokes equations use an average of the viscous fluxes from neighboring elements. The paper presents a methodology for constructing a set of stable boundary/interface conditions that can be thought of as "viscous" Riemann solvers and are compatible with the inviscid limit.

Runge-Kutta methods that require only two memory locations per variable and have strong local order @c=1.5 for non-commutative systems of stochastic differential equations driven by one Wiener process are devised in this paper. A first step in the derivation is to extend existing deterministic methods to the commutative stochastic case, for which higher accuracy is also obtained. Numerical results are presented to validate the approach.

We present in this paper the status of Arctic skua (Stercorarius parasiticus) among the birds that inhabit the western coast of Spitsbergen in Kapp Linne. On the species's kleptoparasitism effectively headed especially towards Kittiwake (Rissa tridactyla), a hypothesis of its double origin was issued: a) by the identity of Reynold indices regarding the wing's morphology and flying capacity in the two birds, b) the strong alikeness until superposition of the both species' emitted sounds, a fact that lets us state the hypothesis that the Stercorarius' cry during the chasing may be a key signal in the prey release by Rissa tridactyla.

The paper develops a numerical method based on the interacting particles approximation (propagation of chaos) for the solution of a large class of evolution problems involving the fractional Laplacian operator and a non-local quadratic-type non-linearity. Coupled stochastic differential equations driven by Levy symmetric @a-stable processes are integrated numerically using Euler's method and the solutions of the governing equations are obtained from their statistics. The method is tested on several one- and two-dimensional examples, and established analytical properties of the solutions are verified for the numerical approximates when they are available. For initial conditions that are either integrable or monotone bounded functions, it is shown that these methods represent viable tools for constructing the solution to the Cauchy problem.

Background: A decreased forced expiratory volume in 1 s/vital capacity (FEV1/VC) ratio is the hallmark of the definition of airway obstruction. We recently suggested that a lung function pattern, we called small airways syndrome (SAOS), has a normal FEV1/VC and total lung capacity (TLC) and reflects obstruction of small airways. Objectives: To substantiate our hypothesis we measured and compared lung function tests including maximal expiratory flow rates (MEFR), sensitive indicators of airway obstruction, in SAOS subjects and in matched controls. Methods: We selected 12 subjects with the pattern of SAOS, but without chronic lung or heart disease (average age: 40.7 ± 7.8 years) and 36 age-matched subjects with normal lung function (42.8 ± 6.3 years). We measured static and dynamic lung volumes, MEFR and lung diffusing capacity (DLCO). Results: SAOS subjects were heavier smokers (p < 0.05) and body mass index was less than in control subjects (p < 0.01). Both FEV1/VC ratio and TLC were comparable in the two groups. However, FEV1, VC, DLCO, and MEFR were lower and residual volume (RV) and RV/TLC ratio were higher (p < 0.05) in the SAOS group than in the control one. Furthermore, the MEFR curve of the SAOS group was displaced to the left without any change in slope, suggesting premature airway closure. Conclusion: Our results suggest that a normal FEV1/VC ratio does not exclude airway obstruction. A decrease of FEV1, provided TLC is normal, reflects small airway obstruction.

Background: Cigarette smoking is the cardinal cause of chronic obstructive pulmonary disease (COPD), but only a relatively small percentage of smokers are developing clinically overt disease, suggesting, therefore, that other risk factors than smoking are involved. Several studies have shown that the bronchodilator response (BR) is related to the progress of COPD, as assessed by the fall in forced expiratory volume in 1 s (FEV1). However, the relationship between BR and fall in FEV1, is a disputed one. Objective: To assess the relationship between BR and fall in FEV1 in a group of long-term smokers and ex-smokers who were 60 years old on the average. Methods: Questionnaire, spirographic tests and BR were assessed in 56 smokers and ex-smokers of mean age 62.5 ± (SD) 2.7 years at the end of a 13-year follow-up period. BR was expressed as a percentage change of the prebronchodilator value (‘% initial’) and as a percentage change of predicted value (‘% predicted’). Results: The FEV1/VC vital capacity was 68.9 ± 7.6% at the start and 64.5 ± 11.3% at the end of the study. The average fall in FEV1 over 13 years was 26 ± 25 ml/year. The FEV1 increased after albuterol on the average with 5.9 ± 6.6%, 4.5 ± 3.9% of predicted, and the vital capacity with 2.5 ± 6.5%, 2.3 ± 6.4% of predicted. BR and fall in FEV1 were correlated: the greater the BR, the more rapid the fall in FEV1 (r = 0.4 and p < 0.01 for FEV1% and r = 0.3 and p < 0.05 for FEV1 predicted). However, when adjusting for prebronchodilator FEV1, the BR was no more related to the fall in FEV1 (r = 0.15, p > 0.05). Conclusions: In long-term smokers and ex-smokers, the BR measured at the end of the follow-up period was correlated with the fall in FEV1. However, after adjusting for prebronchodilator FEV1 values, BR was no more related to the decline in FEV1. The BR appears not to be associated with the development of COPD.

Background Cigarette smoking is the cardinal cause of COPD, but only a relatively small percentage of smokers have development of clinically overt disease. Objectives To identify high-risk subjects and to assess the prognostic significance of "small airways" tests. Setting University teaching hospital. Subjects Fifty-six smokers and ex-smokers of mean age 62.5 years (SD, 2.7) with a smoking history of 40.6 (18.9) pack-years were studied at the end of a 13-year follow-up period. Measurements Questionnaire and lung function tests, including static and dynamic lung volumes, airway resistance, maximal expiratory flow rates, and small airways tests, such as nitrogen slope of the alveolar plateau (N2 slope) and closing volume. Results Eighty-two percent of subjects with a normal FEV1/vital capacity (VC) ratio at the start of the study (half of them with abnormal results of small airways tests) still had a normal FEV1/VC ratio 13 years later. In the remainder, all but one had final FEV1/VC values >60%. About 80% of subjects with a decreased FEV1/VC at the start (subjects with airflow obstruction) reached at the end of study lower than predicted FEV1/VC values. Only about 10% of these subjects showed an accelerated loss of FEV1, reaching end FEV1/VC values of Conclusion Middle-aged smokers are at no evident risk of functional deterioration if their FEV1/VC ratio is normal. This is so even if results of small airways tests are abnormal. A decreased FEV1/VC ratio has no serious implications in itself. Only an associated high N2 slope adds the necessary information to predict a low FEV1. Present data suggest that a subgroup of smokers in their 50s, characterized by a low FEV1/VC ratio and a high N2 slope, are probably the susceptible smokers at high risk for development of COPD.

Several organs (lung, skin, thyroid, heart, bone marrow) are potential targets of cobalt (Co). Whereas there is no doubt that inhalation of Co alone may cause bronchial asthma, its role in the occurrence of hard metal disease is still controversial because most cases were reported in workers exposed not only to Co but also to other substances such as tungsten carbide, titanium carbide, iron, silica and diamond. To assess whether exposure to pure Co dust (metal, oxides, or salts) may lead to adverse health effects a cross sectional study was carried out among 82 workers in a Co refinery. The results were compared with those in a sex and age matched control group. The Co group had been exposed for 8.0 years on average (range 0.3-39.4). The geometric mean time weighted average exposure assessed with personal samplers (n = 82) was about 125 micrograms/m3 and 25% of the values were higher than 500 micrograms/m3. The concentrations of Co in blood and in urine after the shift were significantly correlated with those in air. Concentration of Co in urine increased during the workweek. A slight interference with thyroid metabolism (decreased T3, T4, and increased TSH), a slight reduction of some erythropoietic variables (red blood cells, haemoglobin, packed cell volume) and increased white cell count were found in the exposed workers. The exposed workers complained more often of dyspnoea and wheezing and had significantly more skin lesions (eczema, erythema) than control workers. Within the exposed group a dose-effect relation was found between the reduction of the forced expiratory volume in one second/vital capacity and the intensity of current exposure to Co assessed by the measurement of Co in air or in urine. The prevalence of dyspnoea was related to the dustiness of the workplace as reflected by statistically significant logistic regression between this symptom and the current levels of Co in air and in urine. No difference between lung volumes, ventilatory performances, carbon monoxide diffusing capacity, and serum myocardial creatine kinase and procollagen III peptide was found between the Co and control groups and no lung abnormalities were detected on the chest radiographs in both groups. The results suggest that exposure to high airborne concentrations of Co alone is not sufficient to cause pulmonary fibrosis. This finding is compatible with experimental studies indicating that interaction of other airborne pollutants with Co particles play a part in the pathogenesis of parenchymal lung lesions.

Negative-pressure ventilation (NPV) induces sleep-related upper airway obstruction. However, the precise mechanism and site of upper airway obstruction during NPV have not been worked out. We studied seven awake healthy volunteers (23–30 yr old) in an Emerson tank respirator. Subjects had the head outside the iron lung and breathed through a pneumotachograph, which yielded the airflow (V) signal. Supraglottic pressure (Psg) was measured with a catheter with the tip at the retroepiglottic level. Diaphragmatic electromyograms (EMGdi) were obtained from an esophageal bipolar electrode. Tidal volume was measured with an inductance plethysmograph. Measurements were done at -10, -20, and -30 cmH2O. At each pressure run subjects were asked to repeatedly relax or to actively breathe in phase with the respirator. Subjects had been previously trained to relax during NPV. During the relax runs there was no EMGdi activity. Stridor or wheezing occurred in all seven subjects during the relax runs but not during the active runs. Two patterns were associated with NPV during relax runs. One pattern was decreases in both V and Psg followed by zero values of these indexes, which corresponded to an inspiratory narrowing and closure of the glottis. These changes were visualized by fiber-optic bronchoscopy in one subject. The second pattern was a decrease in V and increase in Psg, which corresponded to an inspiratory supraglottic obstruction. In five subjects a supraglottic pattern was observed, whereas in two subjects glottic closure was seen. We conclude that muscular relaxation during NPV produces a decrease in the caliber of the upper airways at the glottic or supraglottic level. An uncoupling of upper airway muscle activity and the diaphragm might be the mechanism responsible for these changes.

Swirling jet flows have been studied experimentally and computationally and the results have been compared with theory. Three-component Laser Doppler Anemometry (LDA) measurements have been carried out for swirling jets of various strengths and swirl distributions. Radial profiles of velocity have been obtained from the jet exit to 50 diameters downstream. The experimental results are consistent with previous results and with similarity theory for weakly swirling turbulent jets. However, the parametric range and spatial domain of the current data set makes it suitable for validation. Computational simulations have also been performed using a combination of Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) approaches. The results have been validated with experimental data and used to explore the mechanisms behind the increased mixing enhancement observed. The combined experimental/computational effort is still ongoing, but the experiences to date have demonstrated the effectiveness of such an approach.

The paper reports the results of numerical investigations of swirling turbulent jet flows by large eddy simulation (LES). Inflow data are provided on the basis of Reynolds-averaged Navier-Stokes (RANS) simulations. In particular, instantaneous inflow data are produced by a forcing that generates correlated noise. In this way, the characteristic length and time scales of inflowing instantaneous turbulent eddies are in consistency with the corresponding RANS profiles imposed at the inlet. The performance of several subgrid-scale stress models is studied. The mechanism of swirl effects is investigated on this basis. It is shown that swirl breaks apart the typical ring structurs of non-swirling turbulent jets into two modes: a helical mode and streamwise braid structures. The interaction of these two modes generates less organized turbulence structures. Correspondingly, swirl may imply a significant increase of the efficiency of the turbulent mixing of scalars.

In modeling of populations and in many other applications parameters are either measured directly or determined by fitting parameters to a mathematical model. These parameters have variability depending on experimental error, the actual population used and many other factors. In this paper we consider that those parameters are random variables with given distributions. We write and solve random differential equations that model Monod growth kinetics. This type of kinetics is useful, for example, in modeling biofilm growth.

Cineradiography of the pharynx during simulated snoring was done in 6 healthy volunteers, and supraglottic pressure and flow rate were recorded in 12 others. We observed, immediately before snoring, a decrease in the sagittal diameter of the oropharynx followed, during snoring, by high-frequency oscillations of soft palate and pharyngeal walls. The pattern of soft palate oscillations was different while snoring through the nose or mouth. During inspiratory snoring through the nose, the soft palate remained in close contact with the back of the tongue and only the uvula presented high-frequency oscillations. Snoring through the mouth resulted in ample high-frequency oscillations of the whole soft palate. Frequency of airflow and supraglottic pressure oscillations was less (P less than 0.05) during mouth (28.2 +/- 7.5 Hz) than during nasal snoring (77.8 +/- 36.7 Hz). This difference may be related to the smaller oscillating mass (i.e., uvula) during nasal snoring. At variance with our previous data, which showed that snoring during sleep, in both heavy (nonapneic) snorers and obstructive sleep apnea patients, was systematically preceded by flow limitation, this was not true during simulated snoring.

STUDY OBJECTIVES: To clarify the significance of a functional lung pattern characterized by a decreased vital capacity (VC) and an increased residual volume (RV), but with a normal FEV1/VC ratio. SETTING: A university teaching hospital. SUBJECTS: Patients with bronchial asthma, pulmonary emphysema, and small airways disease, and older subjects. MEASUREMENTS: Measurements of static and dynamic lung volumes, diffusing capacity of the lung for carbon monoxide (as measured by the single-breath method), nitrogen slope of the alveolar plateau, and closing volume (as measured by the single-breath O2 test). CONCLUSION: A functional pattern characterized by a decreased VC and FEV1 and increased RV, but with a normal FEV1/VC ratio and total lung capacity, reflects an obstructive impairment of small airways.

According to a recent theoretical model, snoring is related to instability of the upper airway (UA). Factors promoting UA instability include increased gas density. The aim of this study was to test the influence of gas density on simulated snoring production and supraglottic resistance. Supraglottic pressure and flow rate (V') were measured in 10 healthy seated subjects during simulated snoring. Subjects breathed three different gas mixtures: Helium-oxygen, He 79%-O2 21% (He-O2); air; and sulphur hexafluoride-oxygen, F6S 79%-O2 21% (F6S-O2) administered in a random order. Supraglottic resistance (Rsg) was measured on its linear range during quiet breathing and V' was measured at the onset and middle of snoring. Linear Rsg increased and V' conversely decreased with gas density. These data are in agreement with predictions of a mathematical model of the upper airway showing that snoring occurs at lower flow rates when gas density is increased.

Nonstandard analysis is applied to derive generalized jump functions for radially symmetric, one-dimensional, magnetogasdynamic shock waves. It is assumed that the shock wave jumps occur on infinitesimal intervals, and the jump functions for the physical parameters occur smoothly across these intervals. Locally integrable predistributions of the Heaviside function are used to model the flow variables across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the physical parameters for two families of self-similar flows. It is shown that the microstructures for these families of radially symmetric, magnetogasdynamic shock waves coincide in a nonstandard sense for a specified density jump function

Studying swirling turbulent jet flows is important for both application-driven reasons and increasing our fundamental understanding of turbulence. Although experimental and numerical studies of swirling jet flows provided some insights into the processes causing the mixing enhancement of momentum and scalars, a definite understanding is still not achieved. The paper describes the development of a combined RANS/LES method for the investigation of the structure of swirling turbulent jet flows. Comparisons with experimental data provide evidence for the suitability of this combined RANS/LES approach.