bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement and Prediction of the Adsorption of Binary Mixtures of Organic Vapours on Activated Carbon
Authors: Wu Jufang , Xie Zili , Guo Kunmin , Claesson Ola
Published: October 2002

This paper describes a modified headspace method for measuring the adsorption equilibrium of mixtures of organic vapours. The advantage of the method relative to the ordinary headspace method is the shorter time needed to reach adsorption equilibrium. The adsorption isotherms of benzene, hexane and pentane on activated carbons were acquired quickly and easily using this method. The method has also been used to measure the binary equilibrium data of benzene–hexane, benzene–pentane and hexane–pentane mixtures on three types of activated carbon.

The ‘Ideal Adsorbed Solution Theory’ (IAST) was used to predict the binary adsorption equilibria from the adsorption isotherms for the single components. Good agreement was obtained between prediction and measurement for the total amount of components adsorbed, as well as for the ratio of compounds in the adsorbed phase. The small deviation noted was probably a result of using the Freundlich adsorption isotherm in IAST modelling.
Surface and Catalytic Properties of the CuO/Al2O3 System as Influenced by Doping with CeO2 or ZrO2 and by γ-Irradiation
Authors: El-Shobaky Gamil A. , Radwan Farouk M. , Turky Abd. El-Mohsen M. , El-Moemen Ayman Abd.
Published: October 2002

The effects of doping the CuO/Al2O3 system with CeO2 or ZrO2, or alternatively treatment with γ-irradiation, on its surface and catalytic properties were investigated using nitrogen adsorption at −196°C, the decomposition of H2O2 at 20–40°C and the oxidation of CO by O2 at 175°C. The pure solids were prepared by wet impregnation with copper nitrate dissolved in the least amount of distilled water of finely powdered solid Al(OH)3 precalcined at 400°C, followed by drying the resulting product and subjecting the same to calcination at 500°C. The doped solids were prepared by treating Al(OH)3 precalcined at 400°C with a known amount of dopant, i.e. cerium or zirconyl nitrate dissolved in the least amount of distilled water, prior to impregnation with the copper nitrate solution. The amount of copper oxide thus introduced was fixed at 13.5 wt% while the amounts of dopants were varied between 1 wt% and 10 wt% CeO2 or ZrO2.

The results obtained indicated that ZrO2 doping increased the degree of dispersion of the CuO phase, while CeO2 treatment had the reverse effect. Doping the CuO/Al2O3 system with CeO2 or ZrO2 led to an increase of 15.4% or 8.1%, respectively, in its BET surface area. The catalytic activity of the system towards the decomposition of H2O2 decreased on doping with ZrO2 but increased when CeO2 was used as a dopant. γ-Irradiation (at 20–160 Mrad) of CuO/Al2O3 solids resulted in a measurable and progressive decrease in their catalytic activity towards H2O2 decomposition.

In CO oxidation with O2, ZrO2 treatment of the CuO/Al2O3 solids brought about a progressive increase in their catalytic activity with the maximum value (a 31% increase) being observed in the presence of 3 wt% ZrO2 but then decreasing with further increases in the amount of dopant present until the final value attained with 10 wt% ZrO2 was smaller than that measured for the pure CuO/Al2O3 catalyst sample. In contrast, the addition of the smallest amount of CeO2 (1 wt%) led to an effective increase of 69% in the catalytic activity of the CuO/Al2O3 system towards the O2 oxidation of CO, which then decreased when further amounts of CeO2 were added to the system although still exhibiting a catalytic activity greater than that of the undoped catalyst sample.

Doping or γ-irradiation of the CuO/Al2O3 system had no influence on the activation energy for the decomposition of H2O2 in the presence of the resulting solid catalysts although the concentrations of catalytically active sites present on the surfaces of the solids investigated were modified by such treatment.
Textural Analysis of Sulphated ZrO2–SiO2 Sol–Gel Catalytic Supports by N2 Sorption and X-Ray Diffraction
Authors: Salmones J. , Bosch P. , Lara V.H. , Esparza J.M. , Felipe C. , Kornhauser I. , Rojas F.
Published: October 2002

The textural properties of sulphated ZrO2–SiO2 catalytic supports of different compositions were investigated through N2 sorption and X-ray diffraction (conventional and SAXS) methods. The materials were synthesised by the sol–gel procedure from a mixture of zirconium(IV) tert-butoxide and tetraethyl orthosilicate. The final products were obtained after drying at 125°C followed by calcination at 400°C. The porous structures of the substrates were found to depend on their composition: at low zirconia contents these were formed by slit cavities while at high ZrO2 concentrations the void structure became open; both cavities and necks were of similar size. In the first case, the pore size distribution function could be obtained from an analysis of the ascending boundary curve of the N2 isotherm since adsorption occurred on a flat surface. In the second case, a unique pore-size distribution was obtained either from the ascending or descending boundary curves of the N2 isotherm. A tubular geometry seemed appropriate for the description of the sorption characteristics of these substrates. Primary descending scanning curves traced within the hysteresis loops of samples having high ZrO2 contents offered further textural information. X-Ray diffraction methods provided compound identification, evidence of phase segregation between ZrO2 and SiO2, and particle and pore-size distributions.
Statistical Physics Modelling of Dye Adsorption on Modified Cotton
Authors: Khalfaoui M. , Baouab M.H.V. , Gauthier R. , Lamine A. Ben
Published: October 2002

Experimental adsorption isotherms for four anionic dyes (Acid Blue 25, Acid Yellow 99, Reactive Yellow 23 and Acid Blue 74) on to cationized cotton have been analyzed using a multilayer adsorption model. For such purpose, the double-layer model showed the best fit with a high correlation coefficient R2. The analytical expression of the model has been established from an application of the grand canonical ensemble of statistical physics. This method allowed an estimation of all the mathematical parameters in the model. Thus, the receptor site density and the half-saturation concentration have been related to physicochemical variables such as the chemical potential, the adsorption energy, the anchorage number, etc. A physical interpretation of the model parameters has been provided and some results relating to the adsorption process discussed.
Computer Cutting Pattern Generation of Membrane Structures
Authors: Xia Xiaoyan , Meek John L.
Published: October 2002

This paper sets out a simple design procedure for generating the cutting patterns of a membrane surface which can then be used for a variety of purposes, including fabric of tension surface. It does this by pre-defining the requirements of the cutting pattern which is set out by the designer on an initially flat surface. A cable net is used for the approximating surface and the cables approximate the warp and weft directions of the fabric (see our previous paper on shape generation). The present work designs the procedure and gives examples of results of the shape finding of a surface with a number of different cutting patterns. An example of a compression membrane surface is also given.
Initial Stress Field Determination of Membranes Using Optimization Technique
Authors: Uetani K. , Fujii E. , Ohsaki M. , Fujiwara J.
Published: October 2002

A two level approach is presented for shape design of membrane structures supported by frames. The stress ratio in each cutting sheet is considered as independent design variable and is optimized to minimize the deviation of the internal shape from the desired distribution. Then the displacements and compliance for the given loads are calculated parametrically with respect to the stress level, and the optimal value of the stress level is found. Various shape can be realized by considering the stress ratio of each cutting pattern as independent design variables. This way, aesthetically efficient membranes may be designed through modification of the internal shape while also reducing the deformation against design loads. Optimal stresses are found for HP-type membranes with various rises and curvatures.
Dynamic Snap-Through Buckling of Truss-Type Structures
Authors: Sheidaii M. R. , Parke G. A. R. , Abedi K. , Behravesh A.
Published: October 2002

Space trusses under certain conditions may be prone to snap-through buckling. The sudden reduction of the load carrying capacity of a single critical compression member, or a group of compression members, may lead to the snap-through buckling of the compression chord of the structure. This temporary loss of equilibrium due to snap-through normally results in a dynamic force being applied to each node associated with the snap-through. In this paper a methodology based on energy methods is presented to determine the dynamic snap-through response of truss structures. Member failure is taken into consideration by carefully following the buckling load-displacement response of the member. It is assumed that the structure is subjected only to static gravitational loading. A one degree of freedom, simple three bar truss, is used to describe the approach. Finally, this method has been used to perform the snap-through buckling analysis of two double layer grid structure providing a load-displacement behaviour from each structure variation to that obtained from a conventional static analysis.
Performance of Single-Layer Barrel Vaults with Different Configurations
Authors: El-Sheikh Ahmed
Published: October 2002

Single-layer barrel vaults are simple structural formations made up of a network of longitudinal, transverse and bracing members in a single layer with curvature in one direction. The configuration of the vault, or in other words the way in which the members are positioned and connected, has a major effect on the vault?s structural performance, aesthetics and cost. The study presented in this paper is intended to help designers of single-layer barrel vaults by identifying the significant differences between vaults with different configurations, and consequently determining which configuration(s) would be best in different conditions of use. The study presented is parametric and covers a wide range of several important parameters including the vault aspect ratio, boundary conditions, span/rise ratio and configuration. Through consideration of these parameters, the study presents an assessment of the effect of the vault configuration on the overall strength, strength/weight ratio, stiffness/weight ratio, overall ductility and sensitivity to local damage.
Evolution of Natural Frequencies in Tensegrity Systems: A Case Study
Authors: Moussa B. , Kahla N. Ben , Pons J. C.
Published: October 2002

In this study, a dynamic analysis of self-stress levels of tensegrity systems is proposed. A direct relation between the first natural frequency of these systems and the levels of self-stress in the elements is established. It constitutes a first step toward the study of the adaptability of tensegrity systems to external loads; this adaptability could be realized by adjusting the levels of self-stress of one or several cable elements. The study is carried out using continuous struts tensegrity systems made of linear associations of simplex type modules.

When subjected to static loading, tensegrity systems show an evolution of their frequencies with respect to the tension levels in the elements. The frequencies are computed assuming the structure oscillates linearly about its static equilibrium position. This evolution can be used, to associate the level of self-stress to a desired resonant frequency of the system. The harmonic dynamic loading of these systems, confirms their non linear characters and show a particular evolution of the tension-frequency relation.
Formex Configuration Processing III
Authors: Nooshin Hoshyar , Disney Peter
Published: October 2002

This is the third paper in a series of papers that are intended to provide a comprehensive coverage of the concepts of formex configuration processing and their applications in relation to structural configurations. In the present paper, the attention is focused on structural forms that are based on hyperbolic paraboloidal, hyperboloidal and annular surfaces. It is shown that these categories of structural forms include many exciting possibilities for lattice and shell structures. The paper also includes sections on structural forms that may be obtained from combinations of simpler forms or through certain composite transformations that are called paragenic transformations.
Investigation of the Behaviour of Wind Turbines under Low Turbulence Wind Conditions and Their Interaction with the Distribution Grid
Authors: Bronzeado Herivelto S. , Feitosa Everaldo A. N. , Rosas Pedro A. C. , Miranda Marcos S. , de Barros Maria Eliza M. , Rohatgi Janardhan
Published: October 2002

Due to the increasing number of wind power plants all over the world, many studies have been carried out to assess the interaction of such plants with the distribution grid. The electrical power generated by wind turbines is strongly affected by fluctuations in the wind speed and structural vibration excitation, leading to undesired disturbances on the electrical grid. In Brazil, the interest for such systems is considerable. This paper presents the results of measurements carried out at the Brazilian Wind Energy Centre (BWEC) in order to analyze the behavior of a 30kW wind turbine and its influence on the distribution grid, under transient/steady state (nearly constant wind) conditions and, also, under special vibration conditions. The low turbulence wind condition is one of the characteristics of the “trade winds” acting on the northeast Brazilian coast.
Optimizing the Geographic Distribution of Wind Plants in Iowa for Maximum Economic Benefit and Reliability
Authors: Milligan Michael R. , Factor Tom
Published: October 2002

By the end of June 1999, 250 MW of wind generation had been dedicated in the State of Iowa. This represents the beginning of what is likely to be significant wind capacity development during the next 20 years in the State as a result of possible governmental mandates and consumers' desire for sustainable sources of energy. After accounting for predicted load growth over the next 15 years, we estimate Iowa's potential wind energy portfolio through to the year 2015. Winds in the Midwest are primarily generated by fronts moving through the region. The purpose of this study is to find the best way to distribute wind-generating capacity among several sites by using an electricity-production, cost and reliability model. We calculate this benefit in terms of reduction in the fuel cost of conventional generators. We also consider system reliability in terms of energy not served (ENS). Our findings indicate that it is beneficial to develop wind power plants at several sites, and that there are many possible combinations of wind locations that can be chosen to obtain diversity benefits. We also calculate capacity credit for the composite wind power plants using two different methods, and calculate a trade-off curve between the economically optimal and the most reliable solutions. The methods we use to find the best geographical locations and sizes of wind power plant are based on a dynamic fuzzy search algorithm and a genetic algorithm. Each procedure produces a solution set that can be analyzed further in other contexts, such as voltage and land use constraints. We illustrate the sensitivity of the fuzzy economic benefit solutions to small perturbations of the capacity selections at each wind site. We find that small changes in site capacity and/or location have small effects on the economic benefit provided by wind power plants.
A Static Synchronous Converter for Power Conditioning in Network Distribution with High Wind Energy Share
Authors: Beck Hans-Peter , Wenske Jan , Wolf Albrecht
Published: October 2002

The integration of renewable energy sources, e. g. wind energy in weak or isolated power systems produces disturbances. Such disturbances are due to the power fluctuations caused by the stochastic fluctuating wind energy, current harmonics in the power system, switching operations, tower effects and reactive power consumption of the wind energy installations. These decrease the power quality at the point of common coupling (PCC). This paper introduces a concept to compensate the disturbances by the use of a static synchronous converter with an active damping circuit. This new concept is based on the principle of the static reactive power converter, and was extended by means of system integration of largely standardized components of the drive-converter technology.

In combination with an active intervention in the pulse-pattern generator of the main converter, it is possible to balance asymmetrical loads and compensate the harmonics. The pulse pattern generator was realized through an assembler-programmed PC.
Community Funded Wind Power — The Missing Link in UK Wind Farm Development?
Authors: Hinshelwood Emily , Tawe Awel Aman
Published: October 2002

This paper considers community funded wind power development, contrasting the position in the UK with other countries. It makes the point that in countries where wind energy is booming, local people are actively involved. Local opposition to wind farms threatens the UK wind industry and may be a result of limited public consultation and participation. Using as a case study a community wind power project in South Wales, the paper argues that greater emphasis should be placed on involving local people and communities in developing the UK wind industry.
Wind Regime and Wind Power in North Patagonia, Argentina
Authors: Palese Claudia , Lässig Jorge L. , Cogliati Marisa G. , Bastanski Marcelo A.
Published: October 2002

The present paper discusses wind and wind power characteristics in a region north of 40° S (North Patagonia, Argentina) as well as wind power projects sustainability. Extreme wind episodes influence most economic and social regional activities. Mean flow pattern was studied in three North Patagonia sites: Neuquén, Mari Menuco and Cutral-Có, by sampling analysis of wind direction and intensity during a year. Gusts were quantified and strong winds were studied. Available meteorological power was also estimated. It was observed that North Patagonia is a place of great wind power potential. However, the energy available, which is related to prevailing strong winds, is also associated to high gust occurrence which certainly restricts exploitation.
Wind Speed Modelling and Short-Term Prediction Using Wavelets
Authors: Hunt Katherine , Nason Guy P
Published: October 2002

The mathematical method of wavelets is explained and used to predict wind conditions using short-term data collected at a site and referred to long term data from, say, a meteorological station. We model the response time-series in terms of a multiscale wavelet decomposition of the explanatory time-series. Preliminary results of this method, using hourly 10 minute averaged data from six locations in the British Isles, allow comparison with a linear regression method in terms of prediction errors over 21 days.
Numerical Study of Unsteady Viscous Flow past Oscillating Airfoil
Authors: Yan Jin , Xin Yuan
Published: October 2002

Accurate simulation of the dynamic stall of an oscillating airfoil is of major importance to wing and wind turbine blade design. However, dynamic stall is complicated and influenced by many factors, such as geometry shape of the airfoil, reduced frequency, etc. The difficulties of simulation are both mathematical (numerical method) and physical (turbulence model). The present paper has introduced a new numerical method (new LU–type scheme and fourth–order higher resolution MUSCL TVD scheme) and q–ω turbulence modelling to calculate the unsteady flowfields of an oscillating NACA 0015 airfoil. The test targets include attached flow, light–stall and deep–stall of the airfoil. The calculated results for attached flow and light–stall are in good agreement with those of experiments. The calculated results for deep–stall also show improvement, especially during the downstroke of the oscillation. However, there is still a significant difference between the results of calculation and experiment in the hysteresis curves of the drag coefficient. One reason is that the q–ω turbulence model still has limitations. Another is that the drag coefficient is difficult to measure and the experiments are not reliable.
Comparison of Wake Models with Data for Offshore Windfarms
Authors: Rados K. , Larsen G. , Barthelmie R. , Schlez W. , Lange B. , Schepers G. , Hegberg T. , Magnisson M.
Published: October 2002

A major objective of the ENDOW project is to evaluate the performance of wake models in offshore windfarm environments in order to ascertain the improvements required to enhance the prediction of power output within large offshore wind farms [1]. The strategy for achieving this is to compare the performance of the models in a wide range of conditions which are expected to be encountered during turbine operation offshore. Six models of varying complexity have been evaluated initially against the Vindeby single wake data in [2] where it was found that almost all of them overestimate the wake effects and also significant inconsistencies between the model predictions appeared in the near wake and turbulence intensity results. Based on the conclusions of that study, the ENDOW wake modeling groups have already implemented a number of modifications to their original models. In the present paper, new single wake results are presented against experimental data at Vindeby and Bockstigen wind farms. Clearly, some of the model discrepancies previously observed in Vindeby cases have been smoothed and overall the performance is improved.
Nonlinear Acoustic Sources in Squeezed Car Tyre Cavities
Authors: Gagen M. J.
Published: October 2002

At high speeds, the grooves cut into car tire treads can be rapidly squeezed and suffer volume losses of around 10%. This decrease in groove volume can occur much faster than air can evacuate from the squeezed groove as ground impact causes the groove walls to move with velocities of order 1m/s, and with accelerations of 103m/s2 over time scales of about 1ms. The resulting volume loss without any accompanying evacuation of air leads to significant increases in pressure and density in the groove. The pressure fluctuations can exceed 10% of ambient conditions which makes the usual approximations underlying use of the acoustic wave equation invalid. The acoustic wave equation can only be used when pressure fluctuations and pressure gradients are small. When substantial pressure fluctuations exist or when shock waves are present the usual acoustic wave equation cannot be used and a fuller treatment is required. This paper presents preliminary analytical and numerical investigations of the various nonlinear effects which might create novel acoustic sources from squeezed cavities in car tires.
Noise Control of a Table Fan
Authors: Tandon N.
Published: October 2002

The cause of high noise generated by a table fan has been investigated. The noise source was identified by sound intensity mapping and frequency analysis of noise signal. The base of the fan stand was radiating high noise. The cause of this noise was found to be due to the resonance of fan stand. The excitation forcing frequencies were traced to the magnetic noise of the fan motor. A substantial noise reduction was achieved when the natural frequencies of fan stand were altered by stiffening its base and by increasing the mass of the base.
A New Technique for the Measurement of Characteristic Acoustic Impedance in Kundt Tubes Based on a Finite Difference Algorithm
Authors: Alba Jesús , Ramis Jaime , Redondo Javier
Published: October 2002

In this paper we present a new technique for the measurement of specific impedance of acoustic materials based on the method of finite differences using acoustic pressure measurements with a single microphone in a Kundt tube. This method permits prediction of the acoustic pressure in all the points of the tube. We show here the algorithm and its modifications for the evaluation of acoustic impedance. Some comparisons with other methods are also considered.
Combating Noise and Vibration in Power Steering Systems
Authors: Berdichevsky Alexander
Published: October 2002

Noise from car components is more noticeable in today's quieter cars. SKF Engineers have looked at power steering units, to tracking down and reduce noise. Results suggest that vibration of the pinion seal is the most common noise source. Two elastomer materials were tested for noise over a range of temperatures, pressures and shaft speeds, resulting in a new proposed criterion for predicting vibration in seals and other rubber frictional components.
Air Blast and Ground Vibrations Due to Blasting at Gevra Project of South Eastern Coalfields Ltd in India
Authors: Puri S. K. , Pal A. K. , Saxena N. C.
Published: October 2002

Blasting in opencast mining is a vital activity and is the source of environmental and socio-economic problems. The annoying circumstances as a result of impacts due to blasting many times lead to unfavourable mining operations, confrontation and sometimes even litigation. Due to the shortage of land and difficulties in land acquisition, blasting operations at Gevra and Dipka opencast projects of South Eastern Coalfields Limited (SECL) were done close to the buildings and surface structures. Peak particle velocity (PPV) and air over pressure levels during blasting were monitored to avoid annoyance and prevent damage to surface structures. Blasting by conventional techniques using detonating fuse produced ground vibrations and air blast noise greater than the desired limits. Properly planned blast design and blast parameters, like spacing, burden, depth of hole, stemming, etc. as well as adoption of a shock tube initiation system reduced the ground vibrations and air blast noise. A relationship was established between the blast parameters, which can be used in conditions similar to those prevailing at Gevra project.
Identification of Gear Errors by Vibrations of a Spur Gearpair
Authors: Amabili Marco , Fregolent Annalisa
Published: October 2002

A new method of identifying modal parameters (natural frequency and damping) and the equivalent gear error of a spur gear pair is developed. The equivalent error is a function of the gear position and is related to the errors of the driving and the driven gears and to the non-dimensional stiffness of the teeth. The method is based on the measurement of the gear torsional vibrations. The test bench is modelled as a single degree of freedom system and must be assembled by using stiff bearings and torsionally compliant shafts.
Considerations on the Relation between Albedo of ICE/Snow and Climate Change
Authors: Kikuchi Ryunosuke
Published: October 2002

Global climate change due to an increase in greenhouse gases such as carbon dioxide is now regarded as a serious worldwide environmental problem. It is described herein that there is a relation between the tropical zone and the polar/subpolar zone in the heat balance of the earth. The main purpose of the present paper is to show how the boreal environment should be incorporated in the study of global warming. The boreal environment is found to be affected by global warming, but this sensitive environment plays an important part in the terrestrial radiation which releases thermal energy into space. This event depends upon a high albedo in the polar/subpolar zones.
A Computer Investigation of the Performance of Virtual Reflectors: Part II — The Effects of Room Conditions
Authors: Oldham D.J. , El-Zeky L.
Published: October 2002

In a companion paper [1] a technique for overcoming acoustic problems resulting from the directional nature of human speech in open stage auditoria by means of virtual reflectors has been proposed. In a following paper [2] the system was applied to a computer model of an open stage auditorium in which there was no background noise and the space was relatively dead. In the current paper the action of the virtual reflector has been systematically investigated in more realistic conditions. It is shown to be capable of functioning in conditions which are more reverberant and in conditions in which background noise is present. In all cases investigated the action of a virtual reflector results in conditions to the rear of the primary source (human speaker) being improved such that they become comparable to conditions at equivalent positions to the front.

It has been shown that the STI at the rear of a human speaker in an open stage auditorium with the virtual reflector system in operation does not increase significantly with increasing gain [2]. This is due to the Modulation Transfer Function (MTF's) being determined by the convolution of two impulse responses multiplied by a gain factor and added to a third impulse response. The resulting impulse response will therefore consists of many ‘reflections’ and hence the MTF's (and the STI values that they determine) will be adversely affected. An attempt was made to reduce the number of ‘reflections’ in the resultant impulse response by the use of a super directional microphone in order to improve the MTF's and thus the STI values. The actual improvement observed was very small and hence it would appear that the use of a super directional microphone is not particularly effective in this context.
Jagged Edge Noise Barriers
Authors: Menounou Penelope , Busch-Vishniac Ilene J.
Published: October 2002

A novel design of traffic noise barriers is presented: barriers that have a jagged instead of the conventional straight top edge. Experimental, numerical, and analytical investigations show that noise barrier performance can be improved by making the top edge jagged. In many, but not all, cases the jagged edge improves insertion loss, by up to 6 dB. The most promising theoretical approach is to model the edge as a directive line source. Besides yielding predictions that agree favourably with measurements, the line source model reveals that the diffracted field behind a jagged edge barrier depends strongly on the receiver location, the portion of the edge on the most direct path between source and receiver, and the inclination of the straight barrier edge segments. Further, because the model is easy to apply, it is a promising and powerful tool for design of optimum edge profiles.
Concert Hall Acoustic Design: An Alternative Approach
Authors: Fricke Fergus
Published: October 2002

A neural network analysis was undertaken to relate the acoustic quality of concert halls to Beranek's six acoustical parameters: IACC, Gmid, EDT, BR, SDI, and TI. The results of the analysis are difficult to generalise but the present work indicates that there is still no reliable method of predicting the acoustic quality of halls. The limitations of the data and the methodology are explained and the results of the analysis are applied to the Concertgebouw, in Amsterdam, to see how changes in the acoustic parameters might change the acoustic quality of this hall. It is also shown that several different combinations of parameters can give reasonable predictions of acoustic quality. Finally, it is shown that there may be a better way of predicting the acoustic quality of halls which uses some of Beranek's acoustical parameters and the number of seats in the hall.
Mathematical Model for the Design of Layered Structures to Provide Vibration and Impact Damping
Authors: Vašut S. , Briš P. , Ponížil P.
Published: October 2002

In this paper a mathematical model for the transmission loss of layered structures is presented, for longitudinal and transverse waves. The model can be used both for harmonic and impact excitation, and includes the visco-elastic characteristics of the material layers. The model has been verified experimentally for several vibrating systems, and a good conformity between measured values and theoretical prediction has been demonstrated. The model can be applied to the design and evaluation of systems for impact sound attenuation in buildings, for the specification of elastic inserts for the prevention of noise propagation in buildings or structures, or for the design of vibration isolation systems for machines.
Prediction and Reduction Evaluation of Floor Vibration Induced by Foot Steps
Authors: Lin F.M. , Chiang C.M. , Chen S.F.
Published: October 2002

A Finite Element Method (FEM) is employed to model floor vibration induced by foot steps. This numerical model is validated by comparison of the vibration values obtained from the prediction model and the measurements. Regression analysis is employed for the validation. A regression correlation value R2 of 0.82 is calculated, which indicates the acceptability of the numerical model. The model may provide designers with helpful information in reducing floor vibration.
Transmission of Structure-Borne Sound in Buildings above Railway Tunnels
Authors: Hassan O. A. B.
Published: October 2002

Transmission of structure-borne sound in buildings above railway tunnels is studied for a specific case: the sound is assumed to emanate from railway traffic and to be transmitted through the rock foundation into the building. Analytical models are presented for the propagation of structure-borne sound upward in buildings. The models are based on the assumption that the vibrational energy propagates from the foundation in the form of quasi-longitudinal waves. A finite ground impedance is taken into account as well as wave reflection from the roof. Results are presented for buildings constructed with either load-bearing walls or columns.
The Image Source-Virtual Barrier Model for Prediction of Reflection Effects from Barriers
Authors: Cheng W.F. , Ng C.F.
Published: October 2002

This study employed a computer program to identify the insertion loss degradation of barrier due the reflection. The mathematical theories of single barrier prediction are based on Maekawa prediction [1], which predicts the attenuation produced by the barrier as a function of geometry and frequency. The single image source concept was used for estimating the reflection effect of the second barrier.

A scale model of a scale 1:20 and a line source made of small speakers were used to verify the accuracy of the computer program. The results from the program agree well with those of scale models. The results show that the region of where the illuminated zone of the virtual source and the shadow zone of the primary source overlap (Ys1 < Y < Ys) is the critical region of noise degradation. Thus, the image source model with a virtual barrier is a very useful and straight-forward tool for the design of parallel barriers. Four barrier design parameters have been analyzed; sound source position, barrier height, distance between parallel barriers and the usefulness of absorptive material applied at the second barrier.
Case Study: Acoustics of St. Basil's Cathedral in Red Square, Moscow
Authors: Lannie M.Y. , Soukchov V.N.
Published: October 2002

Detailed acoustic measurements were obtained in the old Russian tent-shaped Cathedral of St. Basil, located in the very centre of Moscow. The measured values of RT60, D50, C80 and RASTI as well as the structure of the early sound reflections in the form of ETC are presented and analysed. Some remarks on the acoustics of Russian tent-shaped churches are given.
Flanking Sound Transmission by Timber-Framed Glass Facades
Authors: Schumacher Rolf , Sass Bernd
Published: October 2002

The results of laboratory measurements of the airborne and structure borne flanking sound transmission of timber-framed glass facades in vertical direction are described in relation to the new European standards. The results of Kij -values should give an answer whether the type of junction with the concrete wall or ceiling is relevant for the sound transmission or can be neglected.
Sound Transmission through Hollow Brick Walls
Authors: Fringuellino M. , Smith R.S.
Published: October 2002

Hollow bricks and blocks are one of the most common forms of material used for wall construction found in Central and Southern Europe. The principle purpose of the perforations (holes) is to increase the thermal insulation properties. As a result of these perforations the block gross density is reduced significantly and these block walls have high anisotropy. Consequently, the acoustical insulation properties are influenced detrimentally in comparison to solid blocks. Due to the large thickness of some of these types of hollow block thick wall effects can occur such as bending shear waves and thickness resonances. These further reduce the sound insulation at high frequencies.

This paper describes the characteristic features of sound transmission through hollow walls. For this study several different types of wall were built of varying thickness and materials and the sound reduction index was recorded. The effects of additional plaster layers is also discussed. It is suggested that the material properties of the block's complex web structure may strongly influence the sound reduction index at the low and high frequencies.
The Influence of Concrete Compaction on the Strength of Concrete Filled Steel Tubes
Authors: Han Lin-Hai
Published: October 2002

Tests on twenty-one concrete filled steel tubes to investigate the influence of compaction methods on the strength of concrete filled steel tubular members are reported. Two parameters were investigated, including slenderness ratio and load eccentricity. It was found that better compaction of concrete resulted in higher values of the ultimate strength of concrete filled steel tubular members. The tests show the importance of good concrete compaction for concrete filled steel tubes.
Influence of Non-Classical Damping on the Seismic Response of Suspension Bridges
Authors: Qin Quan , Lou Lei
Published: October 2002

Modern suspension bridges have stiffening steel decks and RC towers. The well separated different materials cause damping to be unevenly distributed for the complete bridge, known as “non-classical” damping. The equations of motion for such structures are damping coupled in the modal coordinate system. Most commercial dynamic finite element analysis computer programs can not solve these equations. This paper discusses three methods for solving the equations and their implementation in computer programs. The seismic response analyses of the Tsing Ma bridge and Humen bridge indicate that non-classical damping may have a significant influence on the seismic response of suspension bridges.
Analytical Benchmark Solutions for Steel Frame Structures Subject to Local Buckling Effects
Authors: Avery Philip , Mahendran Mahen
Published: October 2002

Application of “advanced analysis” methods suitable for non-linear analysis and design of steel frame structures permits direct and accurate determination of ultimate system strengths, without resort to simplified elastic methods of analysis and semi-empirical specification equations. However, the application of advanced analysis methods has previously been restricted to steel frames comprising only compact sections that are not influenced by the effects of local buckling. A research project has been conducted with the aim of developing concentrated plasticity methods suitable for practical advanced analysis of steel frame structures comprising non-compact sections. This paper contains a comprehensive set of analytical benchmark solutions for steel frames comprising non-compact sections, which can be used to verify the accuracy of simplified concentrated plasticity methods of advanced analysis. The analytical benchmark solutions were obtained using a distributed plasticity shell finite element model that explicitly accounts for the effects of gradual cross-sectional yielding, longitudinal spread of plasticity, initial geometric imperfections, residual stresses, and local buckling. A brief description and verification of the shell finite element model is provided in this paper.
Behavior of Framed Shearwalls Made of Corrugated Steel under Lateral Load Reversals
Authors: Mo Y.L. , Perng S.F.
Published: October 2002

Reinforced concrete buildings with shearwalls are very efficient to resist earthquake disturbances. In general, reinforced concrete frames are governed by flexure and low-rise shearwalls are governed by shear. If a structure includes both frames and shearwalls, it is generally governed by shearwalls. However, the ductility of ordinary reinforced concrete framed shearwalls is very limited. The experiments on framed shearwalls made of corrugated steel was recently reported. It was found that the ductility of framed shearwalls can be greatly improved if the thickness of the corrugated steel wall is appropriate to the surrounding reinforced concrete frame. If the thickness of the corrugated steel wall is too large when compared to the surrounding frame, the ductility will be reduced. It is shown in this paper that the fiber-reinforced plastic composites can be used to strengthen the critical regions of the reinforced concrete frames, so that the seismic behavior (including ductility and energy dissipation capability) is greatly improved.
Exact Analytical Solutions for Static and Dynamic Analyses of Cyclic Bi-Periodic Structures
Authors: Gao L. , Liu J. K.
Published: October 2002

The U-transformation method can be used to uncouple linear simultaneous equations with cyclic bi-periodic properties. For a system consisting of masses and springs with cyclic bi-periodicity, this paper presents a procedure demonstrating how to apply the U-transformation technique twice in order to uncouple the governing equations of the mass-spring system and obtain exact analytical solutions. The paper also produces the static, natural vibration and forced vibration analyses for the system. Exact explicit solutions are given for these analyses. The availability of these exact solutions not only helps the checking of the convergence and accuracy of numerical solutions, but also provides a basis for the optimum design of these types of structures.
Regional variation in electrically‐evoked contractions of rabbit isolated pulmonary artery
Authors: Jackson V Margaret , Trout Stephen J , Cunnane Tom C
Published: October 2002

Electrically‐evoked contractions in different regions of the rabbit isolated pulmonary artery have been investigated using stimulation parameters generally assumed to stimulate nerves selectively.

In extrapulmonary artery, trains of stimuli (10 Hz; pulse width 0.1 ms) evoked monophasic contractions. In contrast, a biphasic contraction was evoked in the intrapulmonary artery consisting of an initial fast component followed by a secondary very long‐lasting component.

The contraction in the extrapulmonary artery was prazosin‐sensitive (1 μM) whereas that in the intrapulmonary artery was prazosin‐resistant.

α,β‐Methylene ATP (1 μM), atropine (1 μM), losartan (1 μM), BIBO3304 (1 nM) or nifedipine (1 μM) had no effect on the biphasic contraction of the intrapulmonary artery. Bretylium (2 μM) abolished the contraction of extrapulmonary artery but only partially inhibited the initial component in the intra region with no effect on the second component.

Tetrodotoxin (0.3–1 μM), abolished the contraction of extrapulmonary artery but only partially reduced the electrically‐evoked contraction of intrapulmonary artery.

Removal of the endothelium and application of sulphisoxazole (0.6–22 μM) had no effect.

Varying the resting tone on the arteries, or applying gadolinium, had no effect on contractions.

Using confocal microscopy and calcium imaging, reproducible whole cell calcium transients were evoked in individual smooth muscle cells in intact preparations but only when direct muscle stimulation was used (pulse width of 5–10 ms). No detectable changes in calcium were elicited when brief pulse widths were used (0.1–2 ms).

Together, these data suggest that noradrenaline is the neurotransmitter inducing contraction in extrapulmonary artery. Noradrenaline and sympathetic nerves appear to play a less important role in the intrapulmonary artery. The tetrodoxin‐resistant component is not mediated by ATP, NPY, acetylcholine, angiotensins, ET‐1, stretch‐activation or Ca2+ influx through L‐type Ca2+ channels. Smooth muscle cells do not appear to be damaged by the stimulation protocol. The mechanism underlying the long lasting contraction of intrapulmonary artery evoked by brief electrical stimuli remains to be elucidated.

British Journal of Pharmacology (2002) 137, 488–496. doi:10.1038/sj.bjp.0704863
Correction of G551D‐CFTR transport defect in epithelial monolayers by genistein but not by CPX or MPB‐07
Authors: Zegarra‐Moran Olga , Romio Leila , Folli Chiara , Caci Emanuela , Becq Frederic , Vierfond Jean‐Michel , Mettey Yvette , Cabrini Giulio , Fanen Pascale , Galietta Luis J V
Published: October 2002

This study compares the effect of three chemically unrelated cystic fibrosis transmembrane conductance regulator (CFTR) activators on epithelial cell monolayers expressing the G551D‐CFTR mutant.

We measured Cl− transport as the amplitude of short‐circuit current in response to the membrane permeable cAMP analogue 8‐(4‐chlorophenylthio)adenosine‐3′‐5′‐cyclic monophosphate (CPT‐cAMP) alone or in combination with a CFTR opener. The correction of G551D‐CFTR defect was quantified by comparison with maximal activity elicited in cells expressing wild type CFTR. To this end we used Fisher rat thyroid (FRT) cells transfected with wild type or G551D CFTR, and primary cultures of human nasal epithelial cells.

In both types of epithelia, cAMP caused activation of Cl− transport that was inhibited by glibenclamide and not by 4,4′‐diisothiocyanato‐stilbene‐2,2′‐disulfonic acid. After normalising for CFTR expression, the response of FRT‐G551D epithelia was 1% that of wild type monolayers.

Addition of genistein (10–200 μM), but not of 8‐cyclopentyl‐1,3‐dipropylxanthine (CPX, 1–100 μM) or of the benzo[c]quinolizinium MPB‐07 (10–200 μM) to FRT‐G551D epithelia pre‐treated with cAMP, stimulated a sustained current that at maximal genistein concentration corresponded to 30% of the response of wild type epithelia.

The genistein dose‐response curve was bell‐shaped due to inhibitory activity at the highest concentrations. The dose‐dependence in G551D cells was shifted with respect to wild type CFTR so that higher genistein concentrations were required to observe activation and inhibition, respectively.

On human nasal epithelia the correction of G551D‐CFTR defective conductance obtained with genistein was 20% that of wild type. The impressive effect of genistein suggests that it might correct the Cl− transport defect on G551D patients.

British Journal of Pharmacology (2002) 137, 504–512. doi:10.1038/sj.bjp.0704882