bluuebunny/crossref_metadata_2025 huggingface dataset:
Dye Adsorption by Modified Cotton. Steric and Energetic Interpretations of Model Parameter Behaviours
Authors: Khalfaoui M. , Baouab M.H.V. , Gauthier R. , Lamine A. Ben
Published: October 2002

The variations of the three parameters, viz. anchorage number, receptor site density and half-saturation concentration, as determined theoretically (Khalfaoui et al. 2002) and related to the adsorption energy, exhibited different behaviours when examined in terms of the adsorption of various dyes on to modified cotton. When plotted against the percentage nitrogen content of these cottons, variations in the effective receptor site density and the inverse of the adsorbed molecules anchorage number allowed the adsorption process to be described topographically in terms of the parallel or perpendicular adsorption of the dye molecule on to the adsorbent surface. The presence of ionic or van der Waals forces in such adsorption was also considered.

The values of the model parameters were found to be related to the magnitude of the steric hindrance arising from the anchorage geometry of the dye molecule. Where the site density was high, a form of dimerization of the dye molecules was favoured. The best conditions for obtaining a high adsorption capacity, necessary for textile dyeing and wastewater depollution, were considered. Through the use of the half-saturation capacity, c1/2, it was possible to determine the change in the adsorption energy when the receptor site spacing was decreased and to relate such variation to the rate of steric hindrance, τ.
The Adsorption and Separation of Ethylene, Oxygen and Carbon Dioxide Gases on Molecular Sieves
Authors: Defu Li , Jinqu Wang
Published: October 2002

The equilibrium adsorption and diffusion properties of ethylene, oxygen and carbon dioxide gases on two kinds of molecular sieve at 25°C were measured by gravimetric methods using a Cahn-2000 electrobalance. On both molecular sieves, the equilibrium adsorption capacity of ethylene was larger than that of oxygen and close to that of carbon dioxide, indicating that it would not be possible to remove oxygen and carbon dioxide gases from their mixture with ethylene in order to effect recovery of the latter via equilibrium separation methods. However, during the early stages of adsorption, the adsorption rates of carbon dioxide and oxygen were faster than that of ethylene thereby suggesting recovery of the latter from the gaseous mixture via kinetic separation based on the difference in adsorption diffusivity. Such separation was conducted using a two-bed column pressure swing adsorption arrangement with the effects of the experimental conditions on the separation being investigated. Oxygen and carbon dioxide may be adsorbed and removed from the gaseous mixture, leaving the output gases rich in ethylene.
Adsorption of Mercury(II) Ions on Procion Blue MX-3G-attached Magnetic Poly(Vinyl Alcohol) Gel Beads
Authors: Denizli Adil , Arpa Çiğdem , Bektas Sema , Genç Ömer
Published: October 2002

Magnetic poly(vinyl alcohol) (mPVAL) gel beads (150–200 μm in diameter) carrying Procion Blue MX-3G (122 μmol/g) were used for the removal of different amounts (50–650 mg/l) of Hg(II) ions from aqueous solutions. The mPVAL gel beads were characterized by swelling tests, electron spin resonance (ESR), elemental analysis and scanning electron microscopy (SEM). The swelling ratio of the mPVAL gel beads, which had a spherical shape and porous structure, was 76%. The presence of magnetite particles in the polymeric structure was confirmed by ESR spectroscopy. The capacity of the beads towards Hg(II) ions increased with time during the first 10 min of adsorption and then levelled off towards an equilibrium adsorption capacity. The adsorption of Hg(II) ions on the plain beads was very low (0.57 mg/g) but increased substantially (to 69.2 mg/g) on beads to which Procion Blue MX-3G had been attached.

The Langmuir adsorption isotherm was applicable to the description of Hg(II) ion adsorption by Procion Blue MX-3G-attached mPVAL gel beads. Such adsorption increased with increasing pH of the aqueous medium and reached a plateau level at ca. pH 6.0. The optimal pH range for Hg(II) ion adsorption was 6.0–7.0.

More than 95% of the adsorbed Hg(II) ions was desorbed within 15 min when 0.1 M HNO3 was used as an elution agent. Regeneration of the Procion Blue MX-3G-attached mPVAL gel beads under these conditions was also reasonable.
Buckling Behaviour of Aluminium Ball Jointed Single Layered Reticular Domes
Authors: Hiyama Yujiro , Takashima Hideyuki , Iijima Toshihiko , Kato Shiro
Published: October 2002

This paper discusses the buckling behaviour of aluminium alloy single layered reticular domes, composed of tubular truss members and ball joint connections, through loading tests and numerical simulations on 1:5 scaled test structures. Based on the presented experiments, an estimation method for the buckling strength of the aluminium reticular domes, which is essential for practical structural design and also for predicting the validity of the non-linear analyses, is proposed. Further, the non-linear analysis is executed for the test models and the applicability of the analysis method for such aluminium reticular domes is discussed.
Seismic Behaviour of Space Structures
Authors: Moghaddam Hassan A.
Published: October 2002

Investigations show that the seismic behaviour of space structures may fundamentally differ from the conventional structures. This paper presents the results of dynamic analyses of double-layer barrel vaults with different configurations and support conditions subjected to a severe earthquake, and highlights some basic influential elements in seismic performance of the space structures. The effect of higher modes of vibration has been examined. The significance of the presence of snow loads on dynamic characteristics and seismic performance of space structures is emphasized. Various hysteresis models were used, and the effects of strength reduction and energy dissipation in compression struts were investigated. The results generally indicate that the induced seismic forces are enormously larger than the conventional seismic forces. The consequences of this finding on seismic design of space structures have been discussed, and remedial suggestions have been proposed.
Experimental Study of Dynamic Propagation of Local Snap-Through in Single-Layer Braced Domes
Authors: Abedi Karim , Parke G. A. R.
Published: October 2002

Nodal snap-through has dynamic characteristics which if neglected may lead to an unrealistic estimation of behaviour. When a local nodal snap-through occurs in single-layer braced domes, kinetic energy is released in a local region of the dome. If the dome is capable of absorbing the kinetic energy released, the instability will not propagate and will remain contained. However, if the dome is unable to absorb the sudden release of kinetic energy, progressive collapse of the structure will occur. The authors have already proposed a procedure for modelling the propagation phenomenon. In the present study, two single-layer braced domes were fabricated and tested to collapse in order to evaluate the accuracy and validity of the proposed procedure. The main objectives of the experimental studies were to obtain reliable experimental data for these types of structures and to use this data to assess the validity of the assumptions made in the theoretical procedure. The experimental results show the reliability of the proposed procedure.
A Review of the Development of Spatial Structures in China
Authors: Shen S. Z. , Lan T. T.
Published: October 2002

The development of contemporary spatial structures for long-span roofs in China was initiated in the 1950s. Space trusses, reticulated shells and cable suspended structures have been developing rapidly since 1980s. Recently there has been a growing interest in tensile membrane structures. Comprehensive theoretical study has been carried out parallel to the engineering application, which provided necessary theoretical support to the development of different types of spatial structures.
Buildings with Spatial Forms in Remote Antiquity of China
Authors: Zhi Zhao-Feng
Published: October 2002

China has a long history and different forms of primitive buildings were built several thousands years ago. Building forms in different times, such as Hemudu Culture, Yanshao culture and Banpo Remains are presented in the paper. It is interesting to find that many of these buildings were in spatial forms.
A Study on Space Masts Based on Octahedral Truss Family
Authors: Wu-Jun Chen , Yao-Zhi Luo , Gong-Yi Fu , Jing-Hai Gong , Shi-Lin Dong
Published: October 2002

Octahedral truss is a kind of geometry-rich structure, which can be used extensively in space missions. Regular octahedron is the basis of other various octahedral trusses. Firstly, five basic units of octahedral truss or derivatives are proposed, and the structural performances are investigated briefly. Mechanism features and formations are then studied for fundamental deployable modules in conjunction with the basic units. And knowledge of geometry is formulated in detail for different deployable modules, especially for variable geometry truss and tensegrity. The corresponding mast formations are also developed. Finally, kinematic analysis approach is proposed concisely for statically determinate deployable octahedral truss, and spares matrix storage and reduced matrix technique are employed to improve the computation efficiency.
Effect of a Cable Rupture on Tensegrity Systems
Authors: Kahla N. Ben , Moussa B.
Published: October 2002

A numerical investigation of the effect of a sudden rupture of a cable component in a Tensegrity assemblage is performed using nonlinear dynamic time history analysis to determine element axial forces and nodal displacements responses of the system. Details of the modeling of the Tensegrity elements as well as the numerical scheme used to integrate the equations of motion are discussed. The investigation is carried on a continuous struts Tensegrity system. The system is constituted by an assemblage of five expanded-octahedron basic modules. The simulation of the sudden rupture of a single cable is realized by replacing this element by its tension, applied as an external force to the extremities of the struts to which this element is attached. This force is then removed instantaneously provoking a load imbalance in the system. This imbalance acts as a triggering mechanism sending an impulsive shock to the damaged structure resulting in a damped vibration motion and large magnitude element axial forces.
A New Frequency Domain Method for Wind Response Analysis of Spatial Lattice Structures with Mode Compensation
Authors: Yan-Li He , Shi-Lin Dong
Published: October 2002

The large span spatial lattice structures have many natural frequencies in a narrow frequency range, the conventional frequency domain method is difficult to contain all significant contribution modes. Through numerical examples, it is found that some high order modes are likely to be overlooked because of their higher positions of modal order, in spite of their significance to wind response. According to the contributions of modes to strain energy of system, the paper presented an efficient method to compensate the errors owing to missing out some significant high order modes. The effectiveness of the proposed method is verified through a numerical analysis of the wind responses of a spherical dome. At last, a simplified method of wind vibration coefficient is present for design of practical projects.
Neural Networks for the Approximate Analysis and Design of Double Layer Grids
Authors: Kaveh A. , Servati H.
Published: October 2002

In this paper, efficient neural networks are trained for the approximate analysis and design of double layer grids using the backpropagation algorithm. Special methods are developed for data classification and data ordering to reduce the non-linearity of the data and to increase the accuracy, speed, and stability of the training.
Domical Space Trusses and Braced Domes: Shaping, Ultimate Strength and Stiffness
Authors: Schmidt L. C. , Selby S.
Published: October 2002

A comparison is made of the responses of a domical single-chorded space truss with out-of- plane web members and a single-layer dome of the same chord configuration. The responses considered are the shaping of the domes from an initially flat condition to possible domical shapes, and the testing to destruction of a dome representative of each type. The tests allow the ultimate strength and stiffness of each type to be compared, and highlight the large strength and stiffness advantages to be gained by the use of an out-of-plane web system rather than a single chorded system without webs.
The Design of a 155m Long-Span Hangar for Xiamen Taikoo Aircraft Maintenance Base
Authors: Yunsun Ding , Chu Frank , Yanbin Zhao , Gengqi Liu , Yixiong Guo , Haoguang Li
Published: October 2002

This paper describes the design of a 155m long-span hangar for Xiamen Taikoo Aircraft Maintenance Base. The roof structure adopted is a steel space truss and front arch frame with prestressed concrete tie. Although the suspended loading is over 1,000 tons, the heaviest among the hangars in China, the steel consumption is quite low due to the adopted rational layout and structural type. The paper introduces the measures taken in the design of the arch frame, H-section bolted plate joints, welded hollow spherical joints, prestressed tie and supports. Finally, wind tunnel test results for the hangar are briefly introduced.
Formex Configuration Processing for a Multi-Layered Long Span Aircraft Hangar
Authors: Ramaswamy G. S. , Prakash N. Surya
Published: October 2002

With the availability of fast computers and powerful packages to match, stress analysis of complex structures, such as a Multi-Layered Long Span Aircraft Hangar described in this paper, for multiple loading conditions, is no longer a problem. But preprocessing of input data continues to be a tedious, time-consuming chore. It is here that formex algebra and its programming language Formian provided a breakthrough. The paper demonstrates the power of these tools in generating the topology of a triple layered space frame and its five-layered front girder in a few pages of text.
Optimal Design of Pantograph Foldable Structures
Authors: Kaveh A. , Jafarvand A. , Barkhordari M.A.
Published: October 2002

In this paper, scissor-link foldable structures known as pantograph structures are studied. Recursive Quadratic Programming Method is used for optimal design of double layer grids, barrel vaults and antenna types of pantographs and space structures. Examples are provided to show the performance of the approach being employed.
A New Approach for Wind Speed Prediction
Authors: Song Y. D.
Published: October 2002

The potential benefits of having wind speed predictability are obvious in wind power generation (knowing wind speed ahead of time is useful in automatic power dispatch, load scheduling, and wind turbine control). A new approach for wind speed forecasting is presented in this paper. This method makes use of memorized wind speed to predict the next step wind speed. It is shown that as long as the wind speed variation is not extremely brisk, the proposed algorithm is able to predict the wind speed with a fairly good precision. The proposed predicting scheme does not assume the precise knowledge of the wind model. The result is verified via computer simulation.
A Short Note on Wind Speed with Height Exponent Estimation by considering Time Series Variations
Authors: Sen Zekai
Published: October 2002

Height extrapolation of wind velocity is frequently used in practical studies, such as wind energy calculations and air pollution modelling. The mean wind profile, i.e. measurements of wind speed as a function of height, is often described for engineering purposes by a “power law”, where there is an exponent value dependent on the atmospheric eddy fluctuations, meteorological lapse rate, and the environmental and topographical conditions. In practical studies, depending on the environmental conditions, the value is obtained rather arbitrarily and subjectively with a typical value of 0.14. In this short Note, perturbation methodology is applied to the power law, and consequently, an objective way of exponent determination is presented on the basis of the wind speed measurements at different heights. Finally, it is observed that the exponent is a function of the wind speed averages, standard deviations and the correlation coefficients between two wind speed time series at different heights.
An Information System for Multiple Criteria Assessment of Renewable Energy Power Plants
Authors: Papazis Stelios A. , Ioannides Maria G. , Fotilas Panayotis N.
Published: October 2002

An information system, built-up from a database and a multiple criteria decision support system, was developed to collect, process, store, assess and disseminate information on renewable energy power stations in Greece. This system is used to support decision-making, control, analysis and visualization regarding the existent installations, and the middle term forecasting of similar ones. The results show that, at national level, the wind and solar photovoltaic power stations, except the solar systems of private producers, are acceptable investments. The low national level of the capacity factor, 18 % for wind and 11% for photovoltaic power stations, is one of the reasons for their low productivity. The study relates to the prices paid for renewables electricity in Greece. The cost of the electric energy generated, and also the total cost of all wind and solar power stations, are high as compared to those of conventional fuels based systems. The wind power systems have acceptable return of investment (9%/y), internal rate of return (20%/y) and payback period (6-11 y). The solar stations have low internal rate of return (<9%/y) and return of investment (0.57%/y) and long-term payback period (22-35 y). Although the renewables are attractive investments with acceptable nationwide levels of financial indexes, they present high variations from one power station to another. Most wind and solar power plants must increase their competitiveness, and some must revise their feasibility criteria and design of installations. Thus, units with higher profits must be developed to an optimal installed rated power, while others must be reconsidered.
Hybrid Wind/Photovoltaic/Diesel System Research at the University of Massachusetts
Authors: McGowan J. G. , Manwell J. F.
Published: October 2002

The past decade has yielded significant developments in the design, analysis and installation of hybrid (wind/photovoltaic (PV)/diesel) power systems. This paper presents a summary of recent progress on this subject in the United States with emphasis on the analytical and experimental work carried out at the University of Massachusetts. Topics discussed here include: 1) system configuration and hardware, 2) modeling and design tools, and 3) recent applications.
Continuous Variable Speed Wind Turbine: Transmission Concept and Robust Control
Authors: Idan Moshe , Lior David
Published: October 2002

This paper presents the theory and design of a novel hybrid mechanical-electrical variable speed wind turbine transmission, and discusses a robust control solution for optimal power output of the wind turbine equipped with such a transmission. The novel, planetary differential transmission would be driven by the variable speed rotor and controlled by a control system to ensure a constant speed of the main generator at a wide range of wind speed variations. Analysis shows that this would lead to an increase in the wind turbine energy output, estimated to be in the range of 15% to 20%, compared to a wind turbine with the same rotor and a fixed transmission. Using robust control design techniques, a single controller is synthesized for efficient operation over the entire anticipated wind speed range. The control system automatically varies the rotor speed to optimize its power output for slow wind speed variation and attenuates high frequency wind gust effects to reduce the resulting fatigue damage. Overall, the new concept provides a cost effective solution for variable speed wind turbine operation. The improved system performance is demonstrated using the results of a numerically simulated dynamic model of the proposed system.
Error Evaluation for Models of Real Time Wind Turbine Simulators
Authors: Diop A.D. , Nichita C. , Belhache J.J. , Dakyo B. , Ceanga E.
Published: October 2002

This paper deals with errors inherent in modelling wind turbine simulators. Firstly, different wind turbine simulators are categorised. The work concerns simulators having a real-time soft simulator and an electromechanical tracking system, using any type of servomotor 15–17. Having presented the wind turbine linearised models, with respect to types of servomotor control (in speed or in torque), an analysis is made of simulator mathematical models and simulation performance evaluation, according to the dynamical behaviour of the electromechanical tracking systems. Next, the simulator performances calculation is presented, followed by a simulation error analysis for some particular cases, in order to highlight the differences between the speed and torque control structures. Finally, a servomotor choice principle is established, illustrated by numerical results obtained with the servomotor of a real time wind turbine simulator.
Project Management in Joint Venture Power Development
Authors: Zhang C.
Published: October 2002

This paper discusses developing renewable power projects in a multi- country Joint Venture (JV) environment. A number of key factors in doing JV renewable power projects are analysed which cover Power Purchase Agreements (PPA), JV arrangements, project company structures and financing structures. A commonly preferred procedure for JV power project development is set out. First hand experiences are also reported to illustrate potential loopholes in JV renewable power project management.
Suction Caisson Foundations for Offshore Wind Turbines and Anemometer Masts
Authors: Houlsby Guy T. , Byrne Byron W.
Published: October 2002

We describe briefly some of the challenges met by the designers of the foundation systems for offshore wind energy developments. Although some experience from the offshore oil and gas industry proves valuable, the size and nature of typical wind turbines means that the loadings on the foundations are quite different from those encountered previously offshore. The most economical solutions are also likely to differ from those conventionally used offshore. We highlight the possibilities of a novel form of foundation: the suction caisson.
Calculating the Natural Frequency of a Horizontal Axis Wind Turbine by the Rayleigh-Ritz Method
Authors: Ye Hangye
Published: October 2002

The Rayleigh-Ritz method of calculating the natural vibration frequency of a structure in the second or further order is very complicated. This paper describes a simplified method of calculating the first and second order natural vibrational frequencies of wind turbine towers.
Wind Turbine Flicker Calculation Using Neural Networks
Authors: Papathanassiou Stavros A. , Kiartzis Spyros J. , Papadopoulos Michael P. , Kladas Antonios G.
Published: October 2002

The connection of wind turbines to the distribution networks may affect the voltage quality offered to the consumers. One of the factors contributing to this effect are the rapid variations of the wind turbine output power, which cause respective fluctuations in the supply voltage, referred to as flicker. This paper presents a neural network based model for wind turbine flicker emission calculations. Neural network training patterns are developed using a simulation model of a typical 500 kW stall-controlled wind turbine, by varying all wind and network parameters that might affect the expected flicker levels. The proposed neural network model predicts flicker emissions with sufficient accuracy under any normal operating conditions (wind speed mean value and turbulence intensity) and network characteristics (short circuit capacity, angle of Thevenin impedance and local load). The paper also includes an extensive discussion on the dependence of the flicker severity on the wind and network parameters considered.
Reliability/Cost Implications of Utilizing Wind Energy in Small Isolated Power Systems
Authors: Karki Rajesh , Billinton Roy
Published: October 2002

The rapid growth of wind energy applications in electric power systems dictates a need to develop comprehensive techniques that can be used to evaluate the economics involved and the reliability of power supply that can be achieved from the utilization of wind energy sources. These sources have the potential to significantly reduce operating costs in small isolated systems which are generally supplied using costly diesel fuel. This paper presents a simulation method that provides objective indicators to help system planners decide on appropriate installation sites, operating policies, selection of wind or diesel units in capacity expansion and optimum wind energy penetration levels when utilizing wind energy in small isolated power systems.
Analysis of Turbulent Separated Flows for the NREL Airfoil Using Anisotropic Two-Equation Models at Higher Angles of Attack
Authors: Shijie Zhang , Xin Yuan , Dajun Ye
Published: October 2002

Numerical simulations of the turbulent flow fields at stall conditions are presented for the NREL (National Renewable Energy Laboratory) S809 airfoil. The flow is modeled as compressible, viscous, steady/unsteady and turbulent. Four two-equation turbulence models (isotropic k–ε and q–ω models, anisotropic k–ε and q–ω models), are applied to close the Reynolds-averaged Navier-Stokes equations, respectively. The governing equations are integrated in time by a new LU-type implicit scheme. To accurately model the convection terms in the mean-flow and turbulence model equations, a modified fourth-order high resolution MUSCL TVD scheme is incorporated. The large-scale separated flow fields and their losses at the stall and post-stall conditions are analyzed for the NREL S809 airfoil at various angles of attack (α) from 0 to 70 degrees. The numerical results show excellent to fairly good agreement with the experimental data. The feasibility of the present numerical method and the influence of the four turbulence models are also investigated.
Offshore Wind Energy – A Review of Some Current Research and Development Projects
Authors: Halliday J.A.
Published: October 2002

This is a short review of current offshore wind energy projects funded from institutional sources in Europe, especially relevant in the UK. The funding bodies are the European Commission, the UK Department of Trade and Industry, and the UK's Engineering and Physical Sciences Research Council. The work of the UK-based Offshore Wind Energy Network (OWEN) is also briefly reviewed, with justification given for a UK Offshore wind energy programme.
New methods in Wind Turbine Tower Design
Authors: Horvath G. , Toth L.
Published: October 2002

The main consideration in this wind turbine tower analysis was the use of Finite Element Modelling (FEM) and Computational Fluid Dynamics modelling (CFD). For application, the first wind turbine installation was planned in the hilly region on the banks of the Danube, near Dunaujvaros, where wind speed measurements were recorded from the beginning of 1999. The topographical and wind speed measurement data were used as input for the pre-feasibility study. Flow around the tower was modelled with CFD, with the on-site wind measurement data used as inlet boundary condition for a dynamic system analysis. The aim was to find the most suitable height and cross section for tower design, considering the possible vibrations and torque. The results were verified with wind tunnel and vibration measurements on physical models.
An Improved Determination of the Tower Height That Maximises the Power Output per Unit Cost of a Small Wind Turbine
Authors: Wood D.H.
Published: October 2002

This Note considers the determination of the optimum tower height, defined as the height that maximises the ratio of average power output to the total capital cost of the turbine and the tower. A previous analysis, Wood (2001), gave the optimum height when the power output increases monotonically as the wind speed increases, that is without any consideration for the rated operation or the necessity of shutting down the turbine to avoid excessive loads at high wind speeds. This deficiency is rectified by assuming that the actual power curve consists of a region where the power increases as some power of the wind speed, followed by a region of constant power, after which the turbine shuts down. Because increasing tower height is associated with increasing wind speed, this change considerably reduces the optimum tower height. Using data from a commercial manufacturer, it is shown that the optimum tower height can be considerably less that the maximum tower height offered for sale. The optimum height is shown to increase with increasing surface roughness.
A Review of the Economics of Offshore Wind Farms
Authors: Barthelmie Rebecca J. , Pryor Sara
Published: October 2002

This paper describes the economics of offshore wind energy in the transition from prototype offshore wind farms, developed and installed during the 1990's, to the commercial wind farms that are currently being installed. Since 1990, 96 MW of offshore wind have been installed in Europe and the costs of electricity produced have fallen from almost twice that at equivalent land sites to the point where the best offshore wind farms compete with moderate onshore locations. We summarise the transition to increasing economic viability and document some factors that may influence the feasibility of offshore developments in the future.
ENDOW: Improvement of Wake Models within Offshore Wind Farms
Authors: Schlez W. , Umaña A. , Barthelmie R. , Larsen G. , Rados K. , Lange B. , Schepers G. , Hegberg T.
Published: October 2002

The partners in the ENDOW (Efficient Development of Offshore Windfarms) project are validating, testing, designing and improving wind farm design tools for the efficient design of offshore wind farms. The different meteorological conditions offshore constitute a challenge for the current design tools and models because they have been developed and tested primarily for the design of land based wind farms. Measured downwind of turbines, wake-affected wind speed profiles at Vindeby offshore wind farm have been compared with the model predictions for single, double and quintuple wake cases. The modelling groups have based on these results adjusted their wake models for offshore wind farm design. This paper presents the data, model comparisons and the improvements to the models.
Boundary-Layer Modelling for Wind Climate Estimates
Authors: Bergström Hans
Published: October 2002

The offshore wind climate over the Baltic Sea area has been investigated using the three-dimensional higher-order closure MIUU-model from Uppsala University. A technique for modelling the wind climate with this type of model is presented. The results are verified against measurements. Following the good agreement between model estimates and observations, it is judged that the model output may be used to analyse different aspects of the offshore winds in a detail, which is not possible with existing observations. The influence from land/sea temperature differences on the wind climate and the effects of the related thermally driven flows could be investigated. An attempt was made to quantify these effects on the offshore wind power potential over the Baltic Sea.
Sodar Wind Velocity Measurements of Offshore Turbine Wakes
Authors: Folkerts L. , Barthelmie R. , Sanderhoff P. , Ormel F. , Eecen P. , Stobbe O.
Published: October 2002

In April 2001 the first offshore wake measurements with a SODAR (sonic detection and ranging) were conducted at Vindeby. Wake effects were measured at distances from the turbine varying from 1.4 to 7.1 rotor diameters. The corresponding calculated relative velocity deficits cover a range from 12% up to 56%. The recorded wake profiles provide excellent reference cases for the development and evaluation of offshore wake models.
New Who Guidelines for Community Noise
Authors: Berglund Birgitta , Lindvall Thomas , Schwela Dietrich H
Published: October 2002

This important document replaces the 1980 Environmental Health Criteria No.12 – Noise. It is destined to become widely used and quoted in relation to environmental noise problems. All who have even a passing involvement in this area must become familiar with it and with its recommended levels. The Report considers noise sources and their measurement, adverse effects on health and noise management, whilst introducing a new set of recommendations and guideline values to take account of changes in knowledge and expectations over the past 20 years. Attention is drawn to inadequacies of equivalent level for intermittent noises, to the need to consider effects of low frequency noise and to the rights of vulnerable sub-groups. The Guide can be viewed in full on the World Health Organisation website – www.who.org
Measurement and Analysis of Railway Noise and Vibration
Authors: Koleva M. , Mladenov K.
Published: October 2002

The acoustic environment, as well as the length and speed of the train, determine noise and vibration levels. The average intensity of the noise (assessing by SEL) varies from 83.9 to 104.1 dB/A: the highest intensity accompanies the passing of express (average 95.32 dB/A); the lowest intensity is measured during the passing of EMU (average 89.24 dB/A). Vibrations of the highest intensity are measured during the passing through free fields (0.750 mm.sec−1). Regardless of the bridge type, the level of vibrations varies between 0.032 – 0.067 mm.sec−1.
Noise Reduction of Passenger Cars Due to Maintenance Activities
Authors: Tandon N. , Mahajan V.
Published: October 2002

Noise reduction of two types of passengers cars due to some maintenance activities has been studied. The noise levels of the cars were measured before and after maintenance activities in service stations, as per the standard stationary test. A total of 91 cars were tested. The results of the measurements indicated that the routine maintenance activity of servicing and tuning resulted in an average noise reduction of about 1 dB(A). Noise reduction was greater in the case of the cars with specific problems such as in silencer, water pump and tappet. The rectification of a silencer problem resulted in an average reduction of about 5 dB(A) whereas about 3 dB(A) noise reduction was measured due to the rectification of water pump and tappet problems.
An Alternative Method for the Characterisation of Fibrous Materials from Measurements of Absorption Using Techniques Based on the Allard and Champoux Model
Authors: Alba Jesús , Ramis Jaime
Published: October 2002

In this work we present a method for characterising fibrous materials from absorption measurements in the Kundt tube. Specific Flow Resistance may be calculated, using techniques based on the Allard & Champoux model. Using this model and taking measurements of absorption as a starting point, the method presented here enables one to achieve a complete characterisation of a fibrous material.
Specification of the Effects of Acoustic Noise on Optical Tools
Authors: Gendreau Michael
Published: October 2002

Optical tools respond to internal vibration that can be excited by the external acoustic environment. The degree to which this occurs depends on many factors, but primarily the correspondence between the resonance characteristics of the tool and the frequency content of the acoustic environment in which it operates. Adverse noise environments, such as those often found in laboratories and microelectronics fabrication facilities, can affect the threshold of resolution achievable by the tool. This paper reviews the (typically somewhat inadequate) state of noise specification for optical tools, and the noise levels in typical spaces in which these are intended to operate. Manufacturer's noise specifications often overstate or understate the sensitivity of their tool when the noise sensitivity criterion is oversimplified. More precise and detailed criteria would be useful, for example, in the design of laboratories, or troubleshooting tool operational problems.
Global Control of Vibration Using a Tunable Vibration Neutraliser
Authors: Brennan M.J. , Dayou Jedol
Published: October 2002

Tunable vibration neutralisers are currently used to control harmonic vibration of structures at the point at which they are attached, and the way in which the characteristics of the neutralisers influence their effectiveness in this role are reasonably well understood. However, the use of tunable vibration neutralisers to control global vibration of a structure has not been so well explored, and in this article the neutraliser parameters that influence the vibrational kinetic energy of a host structure are highlighted. It is shown that in general a de-tuned rather than a tuned vibration neutraliser is required at most frequencies, offering a stiffness-like or a mass-like impedance to the structure. However, because this control strategy requires a measure of the global vibration of the host structure, which can be difficult and/or costly in practice, it is preferable to use a tuned vibration neutraliser. For this to be effective it is demonstrated that the tuned neutraliser needs to be appropriately positioned on the structure. If this is the case then such a device can be almost as effective as a de-tuned neutraliser over quite a wide range of frequencies.
Blade and Shaft Crack Detection Using Torsional Vibration Measurements Part 3: Field Application Demonstrations
Authors: Maynard Ken , Trethewey Martin
Published: October 2002

The primary goal of the this paper is to summarize field demonstrations of the feasibility of detecting changes in blade and shaft natural frequencies (such as those associated with a blade or shaft crack) on operating machinery using non-contact, non- intrusive measurement methods. Laboratory demonstration of feasibility and some special signal processing issues were addressed in Parts 1 and 2 [1, 2]. Part 3 primarily addresses the results of application of this non-intrusive torsional vibration sensing to: a large wind tunnel fan; a jet engine high-pressure disk; a hydro station turbine; and to a large coal- fired power plant induced-draft (ID) fan motors. During the operation of rotating equipment, torsional natural frequencies are excited by turbulence, friction, and other random forces. Laboratory testing was conducted to affirm the potential of this method for diagnostics and prognostics of blade and shafting systems. Field installation at the NASA Ames National Full-Scale Aerodynamic Facility (NFAC) reaffirmed the ability to detect both shaft and blade modes. Installation on a high-pressure (HP) disk in a jet engine test cell at General Electric Aircraft Engines demonstrated that the fundamental mode of the turbine blades was clearly visible during operation. Field installation at a hydro power station demonstrated that the first few shaft natural frequencies were visible, and correlated well with finite element results. Finally, field installation on the ID fan motors also showed the first few shaft torsional modes. These field tests have resulted in high confidence in the feasibility of the application of this technique for diagnosing and tracking shaft and blade cracks in operating machinery.
Low-Frequency Airborne Sound Transmission through Single Partitions in Buildings
Authors: Osipov A. , Mees P. , Vermeir G.
Published: October 2002

The low-frequency (20–250 Hz) airborne sound transmission of single partitions is investigated. Three theoretical models are used for the prediction: an infinite plate model, a baffled plate model and a room-plate-room model. The calculation models are verified by detailed comparisons with experimental results obtained in the laboratory. A parametric study is carried out to examine the influence of the dimensions of the room and the partition. The results demonstrate the strong modal behaviour of the low-frequency sound transmission. As a result, the low-frequency sound insulation depends not only on the properties of the test wall, but also on the geometry and the dimensions of the room-wall-room system.
Noise Control of Portable Generator Set
Authors: Tandon N. , Nakra B.C.
Published: October 2002

Major noise sources in a noisy portable I.C. engine driven generator set have been identified. The generator set engine is petrol start and kerosene run. The exhaust silencer of the engine was providing substantial insertion loss. The separation of engine combustion and mechanical noise indicated that their contribution was almost equal. Since generally combustion noise is more than mechanical noise, the main noise sources we re considered to be mechanical in nature. Sound intensity measurements we re performed to identify major noise sources in the generator set when the exhaust was ducted away. The results of these measurements indicated that the main sources of noise in the generator set are: cooling fan cover, silencer shell, silencer cover and the engine crankcase. Noise control measures were applied to these parts. Sound pressure and power levels we re measured before and after the application of noise control measures. Constrained layer damping treatment and stiffening of the cooling fan cover had a combined effect of reducing the sound pressure level by about 3 dB(A). Rigid clamping of the silencer also reduced the noise level. A partial enclosure was designed for the generator set. The partial enclosure reduced the sound pressure and power levels by about 4 and 3.7 dB(A) respectively. There was an increase in the engine cylinder head temperature due to the enclosure, but the increase in temperature was considered to be safe. An overall noise reduction of 8.5 dB(A) was obtained on side 4 of the generator set as a result of the implementation of all the noise control measures. The noise reduction on the other sides of the generator set was also substantial.
Retrofitting Active Control into Well Designed Passive Vibration Isolation Systems
Authors: Margolis Donald
Published: October 2002

Active vibration control uses sensing and power actuators to attenuate vibrational energy due to external disturbances. Many of these systems are retrofitted into already existing passive ones. As a result allowable relative motions are prescribed, and this influences the performance of the active system. This paper exposes these limitations and shows realistic expectations for two excellent control strategies.
A Finite Difference Method for Predicting the Sound Absorption Coefficient of a Fibrous Sample in a Standing Wave Tube
Authors: Uris Antonio , Alba Jesus , Ramis Jaime , Cervera Francisco
Published: October 2002

The paper concerns a comparison between measurements and predictions of the sound absorption coefficient of a fibrous sample in a standing wave tube. A finite difference method has been used to test the predictions. The material parameters used in the finite difference method have been determined using an empirical model.
The Environment: Modernising Justice?
Authors: Day Martyn
Published: October 2002

In this article I review what has happened in environmental litigation in the Britain over the last ten years as a part of determining the extent to which the litigation process has played a part in protecting the environment. I consider a number of the key cases in the 1990s and the decisions made by the Courts. My conclusions are that the Courts have dramatically failed to protect the interests of the individual; that they have put before the individual claimant or applicant enormous hurdles that are almost insuperable; and that combined with the steadily reducing level of funding in these claims the prospect of these types of claim ever succeeding has to be seriously put into question at what damage not only to the environment but also to the British sense of fairness?
How Valid are the Biological and Ecological Principles Underpinning Global Change Science?
Authors: Makarieva Anastassia , Gorshkov Victor G. , Mackey Brendan , Gorshkov Vadim V.
Published: October 2002

The prevailing scientific approach to investigating and understanding the environmental consequences of human-induced global change is underpinned by two basic biological principles. First, the principle that species genetically adapt to changing environment conditions. Second, the principle that nutrients present in the environment in the smallest relative concentrations limit biological productivity.

We contend that both principles have been formulated based on the results of investigations into either artificially selected organisms, or anthropogenically perturbed landscapes. In both these cases, organisms are studied outside their natural ecological niche. We argue that natural ecosystems do not conform to the above two principles. Non-perturbed biota of natural ecological communities form and maintain optimal environment conditions by buffering the flux of primary environmental resources that would otherwise randomly fluctuate as the result of purely physical processes. In such a biotically-mediated environment the availability of nutrients does not limit biological productivity. Critically, the capacity of the biota to regulate local environment conditions obviates the need for species to continually adapt to random environmental fluctuations.

We illustrate how the failure to distinguish between the functioning of perturbed and unperturbed biota prevents the development of policies and strategies that will lead to the long term resolution of the global ecological crisis.
The UN IPCC'S Artful Bias: Summary of Findings: Glaring Omissions, False Confidence and Misleading Statistics in the Summary for Policymakers
Authors: Wojick David E.
Published: October 2002

The UN IPCC WG1 Summary for Policymakers (SPM) of the Third Assessment Report is not an assessment of climate change science, even though it claims to be. Rather, it is an artfully constructed presentation of just the science that supports the fear of human induced climate change. It is as one sided as a legal brief, which it resembles. Line by line analysis of the SPM reveals that all of the science that cuts against the theory of human interference with climate has been systematically omitted. In some cases the leading arguments against human interference are actually touched on, but without being revealed or discussed. In other cases the evidence against human interference is simply ignored. Because of these strategic omissions, the SPM voices a degree of certainty that is entirely false. Glaring omissions are only glaring to experts, so the “policymakers” – including the press and the public – who read the SPM will not realize they are being told only one side of a story. But the scientists who drafted the SPM know the truth, as revealed by the sometimes artful way they conceal it. This deliberate distortion can only be explained by the fact that the UN IPCC is part of an advocacy process, organized by the United Nations Environment Program and supporting the Kyoto Protocol. What is systematically omitted from the SPM are precisely the uncertainties and positive counter evidence that might negate the human interference theory. Instead of assessing these objections, the Summary confidently asserts just those findings that support its case. In short, this is advocacy, not assessment.