bluuebunny/crossref_metadata_2025 huggingface dataset:
Textural and Structural Modification of Homo-Ionic Montmorillonite
Authors: Hassan Mervat S.
Published: August 2010

The textural and structural modifications of calcium bentonite (CaB) induced by ion exchange, heat treatment and acid leaching were studied by infrared spectroscopy (IR), scanning electron microscopy (SEM) and nitrogen adsorption/desorption methods. The cation-exchange capacities (CEC) and the spontaneous and mechanical dispersion of the heat-treated samples were also measured. CaB taken from the northern coast of Egypt consisting of calcium montmorillonite (85%) and kaolinite, in addition to traces of quartz, was used in this study.

CaB and its sodium and lithium forms, NaB and LiB, were calcined at 600 °C for times ranging from 2 h to 20 h, while selected calcined samples were leached with H2SO4 for 1 h. Upon heating, the decrease in the layer charge caused by the fixation of Ca2+, Na+ and Li+ ions in the structure, as revealed by the CEC values, led to an upward shift of the Si–O stretching band in the IR spectrum to the frequency at which the Si–O groups of pyrophyllite absorb. The CEC values showed that the layer charge of the homo-ionic montmorillonite decreased with increasing thermal treatment time and that the amounts of fixed cations were in the order: Li+ > Na+ > Ca2+.

The dispersability of the thermally-treated CaB was higher than that of NaB and LiB, both before and after mechanical dispersion. The high dispersability of CaB arises from the inability of the large Ca2+ cation to penetrate further into the lattice. The textural parameters of heated samples showed that the zig-zag alignment of the silicate chains varied as a function of the heat-treatment time, irrespective of the nature of the exchangeable cations. A significant increase in the amount of pores with diameters in the range 13–38 Å was detected in the case of LiB. Heating LiB further for up to 20 h led to a slight increase in the specific surface area and pore volume, but with a considerable reduction in microporosity. On the other hand, thermal treatment after leaching led to a considerable increase in the specific surface areas, pore volumes and microporosities for those samples subjected to heating for a short time, but decreased progressively with increasing heating time, with no difference being observed to the exchangeable cations. This increase in surface area was mainly due to the presence of micropores whose formation was attributed to the leaching of octahedral cations. On the other hand, following calcination for a long time, the magnitude of the textural parameters diminished due to the gradual collapse of the microporous structure.
The Influence of Solvents on the Liquid-Phase Adsorption Rate of n-Hexane in 5A Molecular Sieves
Authors: Jun Cao , Benxian Shen
Published: August 2010

The main branched hydrocarbons in naphtha are isomeric hydrocarbons, cyclo-paraffins and aromatics. The naphthenic base naphtha has a high content of cyclo-paraffins while aryl naphtha has a correspondingly high content of aromatics. The work described in this paper investigates the influence of each type of principal branched hydrocarbon in naphtha on the adsorption kinetics of n-hexane in 5A molecular sieves at 283 K, 303 K and 323 K, respectively. The results obtained indicate that the effect of the solvent on the adsorption rate decreased in the sequence toluene > methyl cyclohexane > iso-octane. The apparent diffusivity coefficients and the apparent diffusional activation energies for the adsorption of n-hexane in 5A molecular sieves in the presence of different solvents were obtained by fitting the data to the kinetic model and the Arrhenius expression. The results indicate that the paraffin base naphtha is the most suitable feed for the adsorption separation of n-paraffins from branched hydrocarbons employing 5A molecular sieves. The kinetic data could also help to predict the adsorption behaviour in the adsorption bed when different kinds of naphtha are employed as the feed.
Removal of Basic Textile Dyes from Aqueous Solutions through Adsorption by Eucalyptus Camaldulensis Barks
Authors: Keskinkan Olcayto , Ersu Cagatayhan B.
Published: August 2010

In this study, the adsorption capacities of Eucalyptus camaldulensis barks were investigated as an alternative tertiary treatment for the removal of textile dyes [Basic Blue (BB41) and Basic Yellow (BY51)] commonly used in the textile industry. The first set of experiments employed an initial dye concentration of 100 mg/ℓ and 3 g of tree barks in order to determine the contact time for breakthrough. Then, the adsorption isotherm constants were obtained for BB41 and BY51 employing concentrations varying between 25 mg/ℓ to 800 mg/ℓ and between 25 mg/ℓ to 500 mg/ℓ, respectively, using the same amount of E. camaldulensis barks. The constants determined via the Langmuir and Freundlich isotherms indicated that both isotherm models were adequate for explaining the adsorption process. According to the Langmuir isotherm, the maximum adsorption capacities (Qmax) of the E. camaldulensis barks for BB41 and BY51 were 164.17 mg/g and 54.68 mg/g, respectively. The applicability of various kinetic models was also investigated. The results indicated that the adsorption kinetics conformed to intra-particle diffusion. Finally, the dimensionless constant separation factor for the adsorbent/adsorbate system was determined.
Concept of Tuning and Constructing Mass-Customized Generative Surfaces
Authors: Markov Ivan
Published: August 2010

Advances in the digital arena have provided additional tools for the exploration of architectural designs and testing of architectural ideas. New tools based on parametric modeling allow architects and engineers to investigate designs of generative forms and surfaces of previously unseen complexity. The latest developments in rapid prototyping and Computer Numerical Control (CNC) techniques offer new means of studying the tectonics and spatial qualities of structures with complex geometry, yet these “free-form” geometries, if they are ever to be realized, must respect the constraints of structural and constructional realities. This paper presents a user-friendly approach to the adjustment of digitally generated forms at the conceptual stage of architectural design. Adjustment is performed with the aim of improving structural performance, constructional efficiency, and feasibility of fabrication without radically changing the architectural intent. Structural performance is enhanced by fine-tuning the geometry, while constructional and fabrication efficiency is enhanced by developing mass-customized joints and members with adjustable lengths, capable of supporting a “free-form.” The approach is tested in the architectural curricula as a design studio assignment for a canopy for the Yungang Grottoes in Datong, Shanxi Province, China, which has recently been declared a UNESCO World Heritage Site.
Floating Offshore Wind Energy — A Review of the Current Status and an Assessment of the Prospects
Authors: Henderson Andrew R , Witcher David
Published: August 2010

In principle, appropriately designed floating support structures need not be more massive nor costly than the jackets or tripods being deployed in German North Sea waters and elsewhere. A number of significant challenges remain, not least the current limited operating experience but also the limited availability of comprehensive design and modelling capabilities, and demonstrated and widely applicable safe and cost-effectively installation methods. This paper assesses the prospects in terms of technology principles, challenges and the potential resource.
Comparison of Theoretical and Numerical Buckling Loads for Wind Turbine Blade Panels
Authors: Gaudern Nicholas
Published: August 2010

Theoretical and finite element (FE) methods for predicting buckling of wind turbine blades are compared. The theoretical method considers the blade skin as separate panels (idealised as cylindrically curved, simply-supported, and under uniform axial compression); established theory provides the critical load. This approach is compared to FE models of individual panels and representative aerofoils. The FE calculation for an idealised panel agrees with the theory (within 10%). Idealising the panel curvature as cylindrical makes little difference to the critical load (<5%). Adoption of a more realistic load distribution over the length of a blade has greater influence: the buckling strain at the root of a blade under a cubically varying bending moment distribution (e.g. flap-wise bending of a tapered blade under uniform incident wind pressure) is 15% higher than that for an idealised panel. The idealised panel method is therefore a conservative method suitable for preliminary design.
Status and Constraints of Wind Energy Resources Utilization in Kenya
Authors: Makanga Jacob T. , Ngondi Eric N.
Published: August 2010

Energy has been identified as the prime mover that propels the wheel of economic development. Access to modern energy affects quality of life and supports the main aspects of sustainable development namely social, equality, economic growth and environmental protection (1). Sub-Saharan Africa and many other countries with low per capita commercial energy consumption continue to exhibit correspondingly low per capita gross domestic products. In a continent where both per capita income and energy consumption are low, the use of renewable energy resources including biomass, solar, wind, geothermal and hydro power energy resources will be among the main solutions to clean and sustainable energy that will fuel economic growth and spearhead the fight against poverty (2–12).

In an attempt to reveal the status and constraints of wind energy resources utilization in Kenya, studies were conducted in several parts of the country. The results indicate that utilization of wind energy is possible after overcoming some constraints.
A Low Cost Wind Turbine and Blade Performance
Authors: Freere Peter , Sacher Matthew , Derricott James , Hanson Bryan
Published: August 2010

A case study was performed on a commercially available low cost wind turbine. The turbine was tested in a wind tunnel with up to 13 m/s wind speed. The blade characteristics were measured as a function of wind speed, yaw angle, with and without a nose cone, and compared to theoretical models. Practical issues are noted as required for reliable operation, in particular the design of blades and their attachment to the turbine.
The Potential for Wind Energy in Nigeria
Authors: Ajayi Oluseyi O.
Published: August 2010

This paper discusses some of the issues of wind energy development and utilization in Nigeria. It surveys the various initiatives of governments and researchers at assessing the prospects and availability of wind energy for electricity production and identifies indices suggesting wind availability. Inland, the wind is strongest in hilly regions of the North, while mountainous terrains of the middle belt and northern fringes have high potential for great wind energy harvest. However, due to varying topography and roughness of the country, large differences may exist within the same locality. Mean wind regimes in the north and south were also found to lie between 4.0 – 7.5 m/s and 3.0 – 3.5 m/s respectively at 10 m above the ground. It is suggested that Nigeria can adequately utilize wind for power generation over much of the country, if the identified challenges are overcome and the suggested strategies are implemented.
Effects of Delamination on the Vibration Charecteristics of Composite Beams
Authors: Rout Mrutyunjay , Baishya Nayanjyoti
Published: August 2010

Development of an early damage detection method for delamination is one of the most important keys in maintaining the integrity and safety of composite structures. The present study focuses on the effects of delamination on the vibration characteristics of beams with single through-width delamination. Comparison is made between experimental study on aluminum specimens and corresponding finite element models created in ANSYS using brick elements. Specimens are made by bonding thin aluminum strips using very thin adhesive layers, with delaminations introduced by inserting cellophane paper at pre-determined locations. Vibration tests are carried out on the specimens, the results of which are compared with those of the finite element analysis. The finite element model was then used to demonstrate the comparison of natural frequency, mode shapes and curvature mode shapes of the intact and delaminated models. Further, the analysis is extended into layered composites of orthotropic materials. Comparisons are made between published experimental results of laminates and results of finite element analyses on models with layered brick elements using ANSYS. Eigen value extraction was done on ‘free’ models, with no constrains between the delaminated layers and models with linear spring connecting the delaminated layers.
Wind Farming in South East Australia
Authors: Miskelly Andrew , Quirk Tom
Published: August 2010

Wind farms in South East Australia are unlikely to supply any significant power output that system operators can rely upon. Wind farms will load the distribution system with sudden variations in power that are not currently predictable and are as significant as the random variations of user demand.
Projection of California's Future Freshwater Requirements for Power Generation
Authors: Keller Arturo A. , Tellinghuisen Stacy , Lee Cheryl , Larson Dana , Dennen Bliss , Lee James
Published: August 2010

Water and energy are inextricably linked. Water is needed for energy production, and energy is needed for the extraction, conveyance, treatment, and distribution of water. Water requirements for electricity generation vary significantly, depending on the primary energy source, conversion technologies, and cooling technologies. Therefore, to meet future demands, integrated planning between both the energy and water sectors is essential. This analysis provides a tool that supports integrated planning by quantifying the water requirements for electricity generation from both renewable and non-renewable sources. Using California as a case study, we assessed the freshwater requirements for current and future electricity generation under several different energy portfolios. Our analysis demonstrated the potentially positive effects of investment in certain renewable resources such as solar photovoltaics, wind power, and waste-based bioenergy. Similarly, dry cooling technologies, if employed in thermoelectric power plants, can greatly diminish the electricity sector's impact on freshwater resources. Conversely, increased reliance on dedicated energy crops may have extraordinary impacts on freshwater resources. Thus, meeting a “renewable energy portfolio” goal or standard requires careful analysis of the freshwater implications of various primary energy sources and their associated conversion processes. A portfolio with reduced water use and carbon emissions could produce a number of environmental benefits. The corresponding increase in electricity costs may result in increasing energy efficiency, potentially with some trade-off with regards to consumer well-being. Converting California's coastal power plants from seawater-cooled to wet recirculating or dry cooled could actually result in a very minor increase in overall freshwater withdrawals. If reclaimed water is used for cooling these plants, this may actually reduce pressure for freshwater withdrawals overall. While the analysis focused on California, the trends are valid for freshwater limited or stressed regions around the world, and may serve to make better decisions when planning energy and water infrastructure.
Re-Emergence of Distributed Generation in Electric Power Systems: Incentives, Values and Issues
Authors: Akorede Mudathir F. , Hizam Hashim , Aris Ishak , Kadir Mohd-Zainal A. Ab
Published: August 2010

Delivery of electrical power to the end users by the wires systems (grids) has been in practice for more than seven decades. However, recent global renewed interest in distributed generation is due to the constraints or shortcomings of this traditional method. These range from the environmental impact of the fossil-fired conventional power plants, unreliability of this system since the long transmission lines are vulnerable to natural hazards which could result to cascading power system failures, to public opposition to upgrading of the existing or installation of new transmission lines whenever the need arises. This paper reviews the main drivers for the renewed global interest in distributed generation; the values that could be derived from adopting this technology, from various perspectives; as well as the factors militating against it despite the potential benefits.
A Decision Support System to Design Operating Strategies of a Power Plant: Adequate Electricity Generation and Abated Emissions Release
Authors: Vongmahadlek Chatchawan , Satayopas Boonsong
Published: August 2010

In this study, a mathematical optimization model using Genetic Algorithms (GA) was developed and applied to search for operation modes of a power plant considering the adequate electricity generation for public demand and abated emissions release for the better air quality. Continuous Emissions Monitoring System (CEMS) equipment that reports hourly emissions (i.e., NOx, SO2, and CO) is used to prepare information of emissions regarding to the electricity production (GWh). Emission sources include sixteen stacks of eight units of power generation (four thermal and four combined cycle power plants) using natural gas and fuel oil. This technique shows the beneficial application of optimization model, GA code, CEMS, and power generation database in a unified framework of a Decision Support System (DSS). We find that the best operating strategy is to partially shutdown the medium power units and to abundantly operate the large units for the compensation of both emissions and electricity. By using this approach, the electricity generation can be sufficiently produced while emissions can be reduced by 1.83 % of NOx/kWh, 10.90 % of SO2/kWh, and 7.55% of CO/kWh.
The Thunderstorm Thermostat Hypothesis: How Clouds and Thunderstorms Control the Earth's Temperature
Authors: Eschenbach Willis
Published: August 2010

The Thunderstorm Thermostat Hypothesis is the hypothesis that tropical clouds and thunderstorms actively regulate the temperature of the earth. This keeps the earth at an equilibrium temperature regardless of changes in the forcings. Several kinds of evidence are presented to establish and elucidate the Thermostat Hypothesis –historical temperature stability of the Earth, theoretical considerations, satellite photos, and a description of the equilibrium mechanism.
Thoughts about the Acoustic Properties of a Closed Space: An Application to Middle Age Churches in Western Europe
Authors: Vernhes Claude , Drabowitch Serge
Published: August 2010

The two reasons for this theoretical analysis of the acoustics of medieval churches are: first, to explain how the pointed arch vaulting in the nave is directed to improve acoustic efficiency; and secondly, to show how the architecture of the churches is uniquely configured to produce an extraordinary resonance for the plain-chant. In an enclosed space, the emission of any sound inevitably produces reverberations; but if we construct a vault of appropriate dimensions, then most of this reverberation can be directed in a coherent way without untoward resonance, whatever the timbre of the original sound. The reverberant sound increases loudness and gives the sound a sonority which is particularly advantageous for religious chants.

In this study, we shall explain the methodology used and the theory behind the structural characteristics of the pointed arch vaulting [1].

After reviewing the acoustic characteristics of a closed space, we will examine the structures of these churches in relation to specifying the sound bandwidth and reflection quality needed to produce such sonority supported by measurement is of reverberation times. These measurements were made by the University of Genoa in several abbatial churches in Provence.
Seismic Response of Double Concave Friction Pendulum Base-Isolated Structures considering Vertical Component of Earthquake
Authors: Faramarz Khoshnudian , Montazar Rabiei
Published: August 2010

The current investigation has been conducted to examine the effect of vertical component of earthquake on the response of base-isolated structures using double concave friction pendulum (DCFP) system. The structure is idealized as a three-dimensional single-story building resting on a DCFP system. The coupled differential equations of motion are derived and solved in the incremental form using Newmark's step-by-step method of integration. Based on these equations, a computer program was developed to study the influence of vertical component of earthquake on the seismic response of isolated structure using DCFP system. To facilitate the investigation, an error function was defined and effect of various structural parameters on this function was studied under Tabas 1978, Northridge 1994 and Kobe 1995 earthquakes motions. The effect of vertical component of earthquake on the peak values of bearing displacement and base shear of the isolated structure is studied using the variation of essential parameters such as isolation period, superstructure period and friction coefficient of sliding surfaces. It is demonstrated that the maximum error caused by neglecting the vertical component of earthquake in determining the peak bearing displacement and base shear of the structure is 5 and 22 percent, respectively.
Methodology of Long-Term Real-Time Condition Assessment for Existing Cable-Stayed Bridges
Authors: Xiong Wen , Xiao Rucheng , Deng Lu , Cai C.S.
Published: August 2010

Difficulty in measuring the total stress of bridge girders in service (due to dead, live, and environmental loads) raises a significant problem in assessing existing cable-stayed bridges without a complete monitoring record from construction to service. To address this problem, this paper develops a practical monitoring methodology that needs to focus only on the variation of the bridge condition during the service period. In the proposed methodology, the variation of the bridge condition is considered with respect to two sub-conditions: the long-term load condition and the service live load condition. Using the varying cable forces as a reflection of the long- term load condition, the effect of time-dependent loads can be entirely traced back from the present to the bridge's completion. The service live load condition is real-time monitored using strain sensors distributed across different cross-sections. Specific bridge design codes are used to set up the assessment criterion by specifying the stress threshold envelopes for checking each sub-condition of the bridge. By using a three-dimensional solid finite element model in the study of service live load condition, it becomes feasible to arrange measurement stations at the exactly same positions as those on the real structure. A case study is conducted through which the advantages of the proposed methodology are demonstrated.
Response Spectrum Method for Kinematic Soil-Pile Interaction Analysis
Authors: Kishida A. , Takewaki I.
Published: August 2010

The detailed seismic responses of pile-soil systems are usually evaluated by a three-dimensional finite-element model which requires a lot of computational resources. In the actual structural design for these models, a computationally efficient method with a reasonable accuracy is preferred from the viewpoint of cost and time. As for the seismic response of a pile-soil system, a kinematic effect due to the forced displacement of the surface ground is considered to be important, especially in soft ground, together with the inertial effect due to the inertial forces from superstructures. In this paper, a new response spectrum method in terms of complex modal quantities is developed for the evaluation of the maximum kinematic seismic response of the pile-soil model to the ground motion defined at the engineering bedrock surface as an acceleration response spectrum. The ratio of the pile-head moment due to the kinematic effect to that due to the inertial effect will be discussed in detail.
Structural Damage Warning of a Long-Span Cable-Stayed Bridge Using Novelty Detection Technique Based on Wavelet Packet Analysis
Authors: Ding You-Liang , Li Ai-Qun , Deng Yang
Published: August 2010

This paper describes the development of a multi-stage scheme for structural damage warning of the Runyang Cable-stayed Bridge using the measured dynamic responses from an on-line instrumentation system. In the first stage, the wavelet packet energy spectrum (WPES) is extracted using wavelet packet analysis from the measured dynamic responses caused by ambient excitations, thus providing parameters warning of occurrence of structural damage. The second stage is to formulate correlation models describing the seasonal relationship between WPES and temperature and the third stage is to classify the measured changes of WPES, whether due to environmental temperature or to structural damage, using a novelty detection technique based on statistical process control. The usefulness of the approach is examined on the Runyang Cable-stayed Bridge using 236 days of health monitoring data. The results reveal that the seasonal change of environmental temperature accounts for variation in the measured WPES, which averaged a 200% variance, and that the approach is able to eliminate the temperature effects and provides a good capability for detecting the damage-induced 10% variance.
Second-Order Analysis and Design of Wall-Framed Structures Allowing for Imperfections
Authors: Liu Y.P. , Chan S.L. , Zhou Z.H. , So D. , Yu R.
Published: August 2010

In design of steel structures including bare steel frames, composite steel-concrete structures and those with walls and slabs, the conventional method considers each member separately and the effective length is then assumed for member resistance check. This involves inconsistency between the analysis method and the design method. The primitive and rather inadequate second-order P-Δ-only analysis considering only the sway effect has been used extensively in industry and in many computer programs. However, as the P-δ effect for member bowing is ignored, the effective length is still required to be assumed for every member.

Researchers in PolyU have completed the second-order P-Δ-δ analysis and design method for bare steel frames and recent research has been directed to the design of walled frames such that the effective length is not required for flexural buckling check. In this paper, the structural shear wall is modeled by finite shell element whereas the imperfect stability function is employed to model beam-column members. The slab is proposed to be modeled by efficient floor elements. The model is compared well with the results by others. The P-δ effect for member bowing is considered so that the section capacity check alone is sufficient to check the structural adequacy without the assumption of effective length, classification of sway and non-sway frame mode and the tedious individual member resistance check.
Seismic Performance of Benchmark Highway Bridge with Variable Friction Pendulum System
Authors: Madhekar S.N. , Jangid R.S.
Published: August 2010

Dynamic response of a benchmark highway bridge isolated with variable friction pendulum system (VFPS) is investigated under six earthquake motions. The study is based on the finite-element model of the benchmark highway bridge in California. The seismic response of bridge isolated with VFPS is compared with the conventional friction pendulum system (FPS). A parametric study is carried out to study the effects of the maximum coefficient of friction, initial time period and isolation period of VFPS. The response of bridge is also compared with the corresponding uncontrolled case, with FPS, and that controlled by alternate sample control strategies. It is concluded that with the installation of VFPS, the seismic response of the bridge under near-fault motions can be controlled significantly. The VFPS is quite effective in reducing the peak response quantities of the bridge to a level comparable to / better than that of the sample controllers.
The Residual Strength of Confined Concrete
Authors: Ali M.S. Mohamed , Oehlers D.J. , Griffith M.C.
Published: August 2010

Structural engineers have long recognised the importance of member ductility in the design of reinforced concrete members to overcome uncertainties in the design procedure as well as in absorbing energy due to dynamic loads such as earthquakes, impact and blast loads. This has lead to much research on quantifying the rotational capacities of reinforced concrete hinges where intrinsic to the analysis is the behaviour of the concrete compressive stress-strain softening branch, of which the residual strength and strain capacities are important parameters. Much of the softening branch research has been based on careful empirical analyses of confined concrete cylinders. This paper shows that shear-friction theory, which is an established area of research, can be used to quantify the residual strength of hydrostatically and spirally-reinforced confined concrete and provide a lower bound to the residual strength of FRP confined concrete. Hence shear-friction theory is shown to provide an additional structural mechanics tool in the analysis and application of confined concrete.
Vibration Analysis of a Rectangular Thin Plate with Two Parallel Cracks
Authors: Yin T. , Lam H. F.
Published: August 2010

The modeling of cracked plates is important to structural damage detection following the model-based approach. However, very little research has modeled plates with multiple cracks. In 2000, Khadem and Rezaee proposed a method for calculating the modal parameters of a plate with a single-crack parallel to one of the sides. The main purpose of this paper is to extend that work and develop a solution method for calculating the dynamic responses of a classically damped rectangular thin plate with two cracks. The basic idea is to treat the cracks as line springs with varying degrees of stiffness along their lines. When the plate is deflected or when it is vibrating, the slope of the plate is discontinuous at the two sides of the crack line. This change in slope varies along the crack as the crack depth is not uniform. In the governing equation, the cracks are considered as the continuity conditions along the crack line. It is assumed that each crack influences the stiffness only in its neighborhood, with that influence vanishing at a sufficient distance from the crack. By following this assumption, the natural frequencies of the cracked plate can be calculated using energy methods, and the time-domain response of the plate can then be calculated using the modal superposition method. The possibility of using the two-dimensional spatial wavelet transform in crack detection is also explored in this paper.
Aeroacoustic Investigation of a Single Airfoil Tip Leakage Flow
Authors: Jacob M. C. , Grilliat J. , Camussi R. , Gennaro G. Caputi
Published: August 2010

Combined near and far field aeroacoustic measurements have been carried out during an original laboratory scale low Mach number (0–0.3) experiment about the tip leakage flow past a single non-rotating airfoil. Such measurements were made possible by the use of a single airfoil located in the potential core of an open jet flow in the anechoic wind tunnel of the Ecole Centrale de Lyon. The airfoil was mounted between two flat plates. A strong tip clearance flow was achieved without rotation by paying a special attention to the choice of the airfoil which was a 5% camber, 10% thickness NACA5510 airfoil that provided a high lift at a 15° angle of attack. The experiment gave rise to an extensive data set obtained with several flow velocity measurement techniques (HWA, LDA, PIV), steady and unsteady pressure measurements on the airfoil and the casing plate as well as far field pressure measurements. Further, cross-analyses of various velocity and pressure signals allowed to locating sources and identifying their mechanisms. Results showed evidence of two components of tip leakage broadband self noise.
One, no One and One Hundred Thousand Methods for Low-Speed Fan Noise Prediction
Authors: Casalino Damiano , Moreau Stephane , Roger Michel
Published: August 2010

A hybrid CFD/integral approach is used to predict the noise spectrum of a real automotive fan cooling system. The tonal and broadband noise spectral components, mainly due to the coherent and random part, respectively, of the unsteady pressure fluctuations induced by the rotor-wake/stator-vane interaction, are computed by applying a Ffowcs-Williams & Hawkings acoustic analogy to the wall pressure field provided by a transient Reynolds-averaged Navier-Stokes simulation, with superimposed random fluctuations computed through a stochastic method. The RANS turbulent quantities are used to generate solenoidal stochastic velocity fluctuations that contribute to define the right-hand side of a Poisson equation for the pressure perturbation. The Poisson equation is cast into a boundary integral equation and solved by means of a boundary element method. The noise spectra at different angles with respect to the fan axis are computed and compared with available experimental data.
Measurements and wall Modeled LES Simulation of Trailing Edge Noise Caused by a Turbulent Boundary Layer
Authors: Greschner Björn , Grilliat J. , Jacob M.C. , Thiele F.
Published: August 2010

A successful comparison between CFD-CAA and measurements of trailing edge noise is shown for a highly loaded and cambered NACA 5510 airfoil at a chord based Reynolds number of aprox. 1 million placed in a quiet low Mach number flow. The simulation is based on a new variant of the DES - the Improved Delayed Detached Eddy Simulation (IDDES).

The flow is fully attached to the airfoil and therefore only the small turbulent boundary structures that interact with the trailing edge generate significant broadband noise in the far field. The IDDES approach is designed to extend the LES region of the original DES approach (hybrid RANS/LES) from Spalart et. al. (1997) to the turbulent boundary layer, as proposed first by Travin et. al. in 2006. The non-zonal blending occures therefore inside the boundary layer - the RANS model acts as a wall model for the LES. The actual work shows the capabilities of this novel approach for the simulation of broadband noise for attached flows. The simulation is compared to measurements from the EC Lyon including PIV and LDA data around the airfoil and unsteady on-wall pressure measurements near the trailing edge. Far field computations are carried out by applying the Ffowcs–Williams and Hawkings analogy to the unsteady wall pressure field and compared to acoustic measurements as well as to a far field prediction based on a trailing edge noise model that is applied to the experimental aerodynamic pressure field.
Subsonic Jet Noise Reduction by Microjets - A Parametric Study
Authors: Zaman K. B. M. Q.
Published: August 2010

The effect of injecting tiny secondary jets (‘μjets’) on the radiated noise from a subsonic primary jet is studied experimentally. The μjets are injected on to the primary jet near the nozzle exit with variable port geometry, working fluid and driving pressure. A clear reduction in the overall sound pressure level in the direction of peak noise radiation is observed that improves with increasing μjet pressure. It is found that smaller diameter ports with higher driving pressure, but involving less thrust and mass fraction, can produce better noise reduction. A collection of data from the present as well as past experiments is examined in an attempt to correlate the noise reduction with the operating parameters. The results indicate that the OASPL reduction, as monitored at a shallow angle, correlates with the ratio of μjet to primary jet driving pressures normalized by the ratio of corresponding diameters ( pμd/ pj D). With gaseous injection, the spectral amplitudes decrease at lower frequencies while an increase is noted at higher frequencies. The amplitude ‘crossover’ is thought to be at least partly due to shock-associated noise from the underexpanded μjets themselves. Such crossover is not seen with water injection apparently because the flow in that case is incompressible and there is no shock-associated noise. Centerline velocity data show that larger noise reduction is accompanied by faster jet decay as well as significant reduction in turbulence intensities. While a physical understanding of the dependence of the noise reduction on pμd/ pj D remains unclear, given this correlation, an analysis explains the observed dependence of the effect on various other parameters.
Comparison of Microphone Array Processing Techniques for Aeroacoustic Measurements
Authors: Yardibi Tarik , Zawodny Nikolas S , Bahr Chris , Liu Fei , Cattafesta Louis N , Li Jian
Published: August 2010

This paper presents a systematic comparison of several prominent beamforming algorithms developed for aeroacoustic measurements. The most widely used delay-and-sum (DAS) beamformer is known to suffer from high sidelobe level and low resolution problems. Therefore, more advanced methods, in particular the deconvolution approach for the mapping of acoustic sources (DAMAS), sparsity constrained DAMAS (SC-DAMAS), covariance matrix fitting (CMF) and CLEAN based on spatial source coherence (CLEAN-SC), have been considered to achieve improved resolution and more accurate signal power estimates. The performances of the aforementioned algorithms are evaluated via experiments involving a 63-element logarithmic spiral microphone array in the presence of a single source, two incoherent sources with similar strengths and with different strengths, and two coherent sources. It is observed that DAMAS, SC-DAMAS and CMF provide the most reliable source location estimates, even at relatively low frequencies. Furthermore, the integrated levels obtained with the array processing algorithms are shown to agree with what a single reference microphone placed at the center of the array measures when the array is appropriately calibrated. It is also shown that, as expected, the aforementioned algorithms are unsuccessful in distinguishing coherent acoustic sources unless the frequency is relatively high. DAS and CLEAN-SC are shown to be around 2 to 90 times faster than the other three algorithms.
Characteristics of Noise Produced during Impingement of a Compressible Vortex Ring on a Wall
Authors: Murugan Thangadurai , Das Debopam
Published: August 2010

Noise produced during normal impingement of a compressible vortex ring on a flat surface is studied in the shock-Mach number (M) range of 1.31 to 1.55. The compressible vortex ring is generated at the open end of a short driver section shock tube. The far-field noise is decomposed into three major components; (i) sound field due to formation and evolution of the vortex ring, (ii) reflected shock and vortex ring interaction noise and (iii) noise due to impingement of the ring on the wall. The impingement noise consists of fluctuating pressure due to deformation and stretching of the vortex ring, formation and growth of a secondary wall vortex ring, lifting-off of the primary-secondary vortex ring pair. All these events are identified using discrete wavelet transform (DWT) of the sound pressure signal and verified with the laser sheet based flow visualizations. Acoustics fluctuations measured at different angular location shows that the noise due to wall-vortex ring interaction is dominant at 10° ≤ θ ≤ 40°.
Online Training in Sports Concussion for Youth Sports Coaches
Authors: Glang Ann , Koester Michael C. , Beaver Sherry , Clay Janet , McLaughlin Karen
Published: August 2010

The purpose of this study was to evaluate ACTive: Athletic Concussion Training using Interactive Video Education, an interactive e-learning program designed to train community coaches of youth ages 10–18 in effective sports concussion prevention and management practices. Seventy-five youth sports coaches from across the country completed the study over the Internet. Results of a randomized control trial demonstrated significant differences between treatment and control participants on measures of: (a) knowledge about sports concussion, management, and prevention; (b) attitudes about the importance of preventing sports concussion; and (c) intention and self-efficacy in sports concussion management and prevention. The results suggest that ACTive is an effective method of training youth sports coaches who are in an important position to reduce risks associated with sports concussion.
Analysing Sporting Efficiency Using Standardised Win Cost: Evidence from the FA Premier League, 1995 – 2007
Authors: Gerrard Bill
Published: August 2010

This study proposes the use of standardised win cost as a simple and transparent measure of sporting efficiency in professional team sports. Standardised win cost measures the ratio of sporting performance (i.e., output) to financial expenditure (i.e. input). The specific version developed for league performance in (association) football is the wage cost per league point standardised across seasons to allow for changes in the general level of player wages as well as league restructuring. The use of standardised win cost to analyse team performance and efficiency is illustrated with data from the FA Premier League for the period 1995 – 2007.
Understanding the Change Process: Valuing What it is That Coaches Do
Authors: Cassidy Tania
Published: August 2010

When coaching is viewed as a rational process it is often assumed that coaches can reflect upon and, where necessary, change their behaviour. In this commentary, it is contended that using a rational argument to change practice is limited if consideration is not given to the way coaches learn how to coach. Knowledgeability is a generative concept for understanding why it is difficult to change time-honoured practices or day-to-day conventions that have often become taken for granted. The aims of this article are to introduce the concept of ‘knowledgeability’ and associated ‘practical consciousness’, and to highlight the explanatory power of the latter for understanding the change process.
Optimal Control of Temperature in Fluid Flow Using Four Types of MinimizationTechniques
Authors: Yamazaki Daisuke , Kawahara Mutsuto
Published: August 2010

The purpose of this paper is a thermal optimal control problem using four types of minimization technique. The four types of minimization techniques are the weighted gradient method, the Newton based method, the modified steepest descent method and the steepest descent method using weighting adaptation. The formulation is based on the optimal control theory in which the performance function is expressed by the computed and targeted temperatures. The optimal values can be obtained by minimizing the performance function. The thermal fluid flow is described by the Boussinesq approximated incompressible Navier-Stokes equation and the energy equation is analyzed. BFGS is applied to calculate the Hessian matrix which is used in the Newton-based method. The traction given by the perturbation for the Lagrange multiplier is used in the BFGS method.
Parallel Support Vector Machines Applied to the Prediction of Multiple Buildings Energy Consumption
Authors: Zhao Hai Xiang , Magoulès Frédéric
Published: August 2010

Analyzing the energy performance in a building is an important task in energy conservation. To accurately predict the energy consumption is difficult in practice since the building is a complex system with many parameters involved. To obtain enough historical data of energy uses and to find out an approach to analyze them become mandatory. In this paper, we propose a simulation method with the aim of obtaining energy data for multiple buildings. Support vector machines method with Gaussian kernel is applied to obtain the prediction model. For the first time, a parallel implementation of support vector machines is used to accelerate the model training process. Our experimental results show very good performance of this approach, paving the way for further applications of support vector machines method on large energy consumption datasets.
Research and Realization of Medical Volume Data Interactive Cutting
Authors: Jian Wu , Hai-Tao Zhai , Jie Xia , Zhi-Ming Cui , Feng Ye
Published: August 2010

Medical image visualization is an important field of scientific computing visualization. Three-dimensional segmentation plays a very important role in three-dimensional reconstruction of human tissues and region of interest. In order to observe the information of human internal tissues better and provide reliable basis for clinical diagnosis, pathological analysis and treatment, it is indispensable to do cutting on volume data. Virtual cutting is usually carried out with the user's interactive operations after three-dimensional reconstruction. This paper does research on the algorithms of cutting volume data, and proposes a series of solutions including plane cutting, bounding box cutting, ball cutting and contour surface cutting. Experiment results indicate that the algorithms are practical and efficient, which can reach favorable virtual cutting effect. By this meaning, doctors can know the internal information of volume data more clearly. Meanwhile, the amount of computation reduced.
Hydrogen and Carbon Black Production from Thermal Decomposition of Sub-Quality Natural Gas
Authors: Javadi M. , Moghiman M.
Published: August 2010

The objective of this paper is computational investigation of the hydrogen and carbon black production through thermal decomposition of waste gases containing CH4 and H2S, without requiring a H2S separation process. The chemical reaction model, which involves solid carbon, sulfur compounds and precursor species for the formation of carbon black, is based on an assumed Probability Density Function (PDF) parameterized by the mean and variance of mixture fraction and β-PDF shape. The effects of feedstock mass flow rate and reactor temperature on hydrogen, carbon black, S2, SO2, COS and CS2 formation are investigated. The results show that the major factor influencing CH4 and H2S conversions is reactor temperature. For temperatures higher than 1100° K, the reactor CH4 conversion reaches 100%, whilst H2S conversion increases in temperatures higher than 1300° K. The results reveal that at any temperature, H2S conversion is less than that of CH4. The results also show that in the production of carbon black from sub-quality natural gas, the formation of carbon monoxide, which is occurring in parallel, play a very significant role. For lower values of feedstock flow rate, CH4 mostly burns to CO and consequently, the production of carbon black is low. The results show that the yield of hydrogen increases with increasing feedstock mass flow rate until the yield reaches a maximum value, and then drops with further increase in the feedstock mass flow rate.
Laser-Based Spatio-Temporal Characterisation of Port Fuel Injection (PFI) Sprays
Authors: Anand C. T. N. , Deshmukh Devendra , Madan Mohan A. , Ravikrishna V. R.
Published: August 2010

In the present work, detailed laser-based diagnostic experiments were conducted to characterise the spray from low pressure 2-hole and 4-hole Port Fuel Injection (PFI) injectors. The main objective of the work included obtaining quantitative information of the spatio-temporal spray structure of such low-pressure gasoline sprays. A novel approach involving a combination of techniques such as Mie scattering, Granulometry, and Laser Sheet Dropsizing (LSD) was used to study the spray structure. The droplet sizes, distributions with time, Sauter Mean Diameters (SMD), droplet velocities, cone angles and spray tip penetrations of the sprays from the injectors were determined. The spray from these injectors is found to be ‘pencil like’ and not dispersed as in high pressure sprays. The application of the above mentioned techniques provides two-dimensional SMD contours of the entire spray at different instants of time, with reasonable accuracy.