bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Aluminium Concentration on the Hydration of ZSM-5-Type Zeolites in Aqueous Suspensions
Authors: Turov V.V. , Brei V.V. , Khomenko K.N. , Leboda R.
Published: October 2002

The 1H NMR spectral technique has been applied to the study of samples of ZSM-5-type zeolites. These samples were synthesized using the template procedure and possessed various aluminium concentrations in their crystal lattice. The characteristics of the adsorbed water layers and the values of the free surface energy of the adsorbents were determined. It was established that, for aqueous suspensions of zeolites, the highest concentration of water in the pores was characteristic of the sample containing the lowest amount of aluminium. It was suggested that the amount of water in the pores is determined not so much by the concentration of primary adsorption sites as by the conditions under which the development of water clusters occurs as well as by the competing sorption of water and ambient air.
The Electrical Double Layer Parameters for the Group 4 Metal Oxide/Electrolyte System
Authors: Janusz Władysław
Published: October 2002

The electrical double layer parameters for Group 4 metal oxide/NaCl solution systems are presented. The surface charge density and the adsorption of background electrolyte ions as a function of the pH of the solution and the concentration of the electrolyte for the ZrO2 and HfO2 systems are presented. Through the use of numerical optimization, the apparent reaction constants for the surface hydroxy group were calculated. The characteristic points of the electrical double layer and the ionization and complexation constants of the surface hydroxy groups are compared with those predicted semi-theoretically.
Synthesis of a Polymer Covering on Al(OH)3 and BaSO4 Surfaces by Means of Radical Polymerization in Water Medium
Authors: Tokarev V. , Seredyuk V. , Voronov S.
Published: October 2002

The graft polymerization of butyl methacrylate on to the surface of Al(OH)3 and BaSO4 fillers initiated by an adsorbed peroxidic macroinitiator was studied in water medium relative to the corresponding polymerization in toluene. It was established that, in water medium, the nature of the solid surface as well as the monomer concentration has only a very slight influence on the rate of grafting and the amount of polymer grafted, both of which depend on the specific surface area of the filler and the temperature. To explain these features, a microreactor polymerization model is proposed in which the filler particles or aggregates of the particles together with the immobilized macroinitiator and adsorbed monomer are considered as microreactors. As a result of graft polymerization, compatibilizing polymer shells were formed on the Al(OH)3 and BaSO4 particles. Due to solvation, such shells enhance the organophilicity of the filler surface sufficiently and provide a high steric stabilization of the filler dispersions in organic media. When both the adsorption of the macroinitiator and the graft polymerization of the monomer proceed in water medium, the efficiency of the process and its ecological cleanliness are increased greatly.
Adsorption Studies of the Effect of Thiosemicarbazides on the Corrosion of Steel in Phosphoric Acid
Authors: Ameer M.A. , Khamis E. , Al-Senani G.
Published: October 2002

The corrosion inhibition of steel in phosphoric acid by thiosemicarbazide derivatives has been studied using different chemical and electrochemical techniques. The observed order of increasing inhibition efficiency was correlated with changes in the molecular structures of the inhibitors. Potentiodynamic polarization curves indicate that the compounds are mixed-type inhibitors. Electrochemical impedance spectroscopy has been used successfully to evaluate the performance of the inhibitors. AC measurements showed that the dissolution process was activation-controlled. The kinetic–thermodynamic model and the Flory–Huggins adsorption isotherm described the experimental findings well. The number of active sites, binding constant and change in free energy were computed for all the inhibitors studied. It was found that the inhibitor molecule was adsorbed through more than one active centre and occupied more than one active site on the steel surface.
Effect of Some Admixtures on the Surface Properties of the Hydration Products of Silica Fume/Ca(OH)2 Mixtures
Authors: Hekal E.E. , Mousa N.A.
Published: October 2002

The effect of sodium naphthalene formaldehyde sulphonate polycondensate and stearic acid on the surface properties of calcium silicate hydrates, formed as a result of the hydration reaction between silica fume and calcium hydroxide, has been examined by the use of low-temperature nitrogen gas adsorption techniques. In addition, the interaction of such admixtures with the calcium silicate hydrates formed was investigated by infrared (IR) spectroscopic analysis. It was observed that both admixtures increased the specific surface area of the calcium silicate hydrates quite considerably relative to the behaviour of a blank sample (i.e. without addition of admixture), especially during the initial stages of hydration (after 24 h). IR examination demonstrated that the admixtures used did not interact chemically with the calcium silicate hydrates although physical interaction was possible.
Removal of Pollutants from Water Using Untreated and Treated Sawdust and Water Hyacinth
Authors: El-Nabarawy Th. , Khedr S.A.
Published: October 2002

Sawdust and water hyacinth are waste products which have no economical application in Egypt. They even constitute a solid waste as far as the environment is concerned. As-received sawdust and water hyacinth were treated with phosphoric acid, phosphoric acid + urea or phosphoric acid + urea + dimethylformamide. The as-received and treated samples were used for the removal of Methylene Blue, iodine, phenol and ammonia from their aqueous solutions.

The optimum conditions for the maximum adsorption of each pollutant were determined. The isotherms obtained obeyed the Freundlich and Langmuir equations in a satisfactory manner. The initial stages of adsorption follow first-order kinetics as predicted from the Lagergren equation. Sawdust and water hyacinth show promising potentialities for the removal of pollutants from water and can, at least, be used as precursors for the preparation of efficient adsorbents for the removal of pollutants from water.
Molecular Species Disturbing the Fluid–Solid Phase Transition of Nitrogen Adsorbed on Graphite: Importance of Aromaticity
Authors: Yano Tsuyoshi , Kamakura Shinya , Ikeda Akari , Asada Hiromu
Published: October 2002

The fluid–solid (FS) phase transition of N2 adsorbed on graphite is known to be depressed abnormally by conjugated coplanar molecules such as benzene and copper phthalocyanine. This paper describes an investigation of the influence of a non-aromatic conjugated species (1,3-butadiene), a non-aromatic cation acceptor (18-crown-6), a strong electron donor (tetrathiafulvalene) and a strong electron acceptor (tetracyanoquinodimethane) on the FS phase transition of N2, when they were preplated on graphite. These species were, in fact, found to have no significant effect. This implies that molecular properties such as cation acceptance and electron transfer are of no importance, whereas the aromaticity of co-existing species plays a crucial role in disturbing the phase behaviour of N2.
Investigation into the Use of Macroporous Anion Exchangers for the Sorption and Separation of Iminodiacetate Complexes of Lanthanum(III) and Neodymium(III)
Authors: Hubicka Halina , Kolodyńska Dorota
Published: October 2002

Rare earth element complexes with iminodiacetic acid (IMDA) of the Ln(IMDA)−2 type exhibit an unusual sequence of affinities for anion exchangers.

In this work, the applicability of strongly basic gel and macroporous polystyrene anion exchangers to the sorption and separation of rare earth element complexes with iminodiacetic acid has been investigated.

It was shown that the acetate forms of both the macroporous and gel anion exchangers were most effective and cheapest for this type of separation.

As far as their applicability to the purification of lanthanum(III) IMDA from the corresponding neodymium(III) complexes is concerned, the anion exchangers investigated may be arranged in the following sequence: strongly basic gel anion exchangers ≈ strongly basic macroporous anion exchangers > weakly basic macroporous anion exchangers.
Removal of Ni2+ and Cu2+ Ions from Aqueous Solution on to Lignite-Based Carbons
Authors: Samra S.E.
Published: October 2002

Non-activated lignites were prepared by the carbonization of Egyptian lignite in a limited quantity of air at 500°C, 700°C and 900°C, respectively. Zinc chloride-activated carbons were also prepared by the carbonization of lignite with 20 wt%, 40 wt% and 60 wt% zinc chloride in a limited quantity of air at 600°C. The surface areas of the resulting samples were determined from nitrogen adsorption studies at 77 K and from carbon dioxide adsorption studies at 298 K. The functional acidic groups on the surface were determined by neutralization with aqueous solutions of NaHCO3, Na2CO3 and NaOH, respectively. The sorption of Ni2+ and Cu2+ ions on the prepared carbons as well as on the as-received lignite (L) were investigated. The influence of the time of contact, the initial ion concentration and the temperature was studied and the kinetics of the process were investigated. Equilibrium sorption isotherms were determined and the results interpreted by applying the Freundlich and Langmuir equations.

The surface area was found to generally increase with increasing carbonization temperature. For activated carbons, the surface area increased with an increase in the amount of zinc chloride used in the activation process. The chemisorption of Ni2+ and Cu2+ ions on lignite-based carbon was found to be a pseudo-second order process. The acid sites on the surface provide active sites for the chemisorption of Ni2+ and Cu2+ ions and a qualitative relationship was found to exist between the maximum sorption capacity of these metal ions and the total surface acidity.
Extension of the Applicability of Jäntti's Method to the Fast Calculation of Desorption Data
Authors: Robens Erich , Massen Carel H. , Poulis Johannes A. , Staszczuk Piotr
Published: October 2002

The time for sorption measurements may be reduced substantially by measuring several values at short time intervals at the beginning of a kinetic curve and extrapolating them to the equilibrium value. The method used by Jäntti for simple adsorption processes has been extended to complicated processes described by a second-order differential equation. A simulated example is provided.
Analysis of the Potentiometric Titration Curves of Weakly Basic Anionites
Authors: Mamchenko A.V. , Chernova L.G.
Published: October 2002

An analysis of the experimental potentiometric titration curves for various classes of weakly basic anionites has been made from the basis of the exchange equilibrium theory. When the NaCl concentration in the external solution differed by more than two orders of magnitude, two curves were obtained for each ionite. Reference to the activities of the chloride ions allowed these two curves to be combined satisfactorily.

The acrylic anionite, Amberlite IRA 67, fulfilled the model of ideal exchange in the gel phase. Systematic deviations from such ideal behaviour were observed for the polystyrene–divinylbenzene anionite, Lewatit MP 62, while the experimental data for Lewatit AP 49 exhibited an essential deviation from a linear dependence when plotted in terms of the extended Henderson–Hasselbalch equation.

Comparative analyses of the titration curves for weakly basic Amberlite IRA 67, strongly basic AB 17-8 and Lewatit AP 49 anion exchangers led to the suggestion that Lewatit AP 49 contained weak and strong basic groups whose behaviour may be described by the extended Henderson–Hasselbalch equation using various effective equilibrium constants but the same value of n (= 1).

An equation for calculating the quantity of strong and weak basic groups in an acrylic anionite has been obtained. An explanation of ideality in terms of weakly dissociating (basic) and strongly dissociating (salt) resinates of weakly basic acrylic anion-exchange resins has been proposed.
Separation of Emulsifiable Oil from a Flotation Solution by Surface Tension Control
Authors: Omar A.M.A.
Published: October 2002

The oil flotation behaviour of emulsifiable oil was studied using N-octyl- N-benzyl- N-methylglycine (OBM) as the collector and heavy alkylate naphthalene sulphonates (HNS) as the de-emulsifier. The study showed that the surface tension has an effect on oil recovery. The interfacial tension at the air/water interface was controlled by the use of an alcohol such as ethanol, n-propanol and n-butanol and compared with the collector when used alone in froth flotation. The adsorption of the collector from the aqueous solution was investigated by measuring the surface tension as a function of concentration at different temperatures. Surface properties, in particular the critical micelle concentration (CMC), the effectiveness of surface tension reduction (ΠCMC), efficiency (PC20), the maximum surface excess (Γmax) and the minimum surface area (Amin), were measured at temperatures of 25, 35 and 45°C, respectively. The results were discussed in terms of the adsorption isotherm and surface properties of the collectors at the solution/air interface.
Removal of Copper(II) from Aqueous Solutions by Flotation Using Limestone Fines as the Sorbent and Oleic Acid as the Surfactant
Authors: Ghazy S.E. , Samra S.E. , El-Morsy S.M.
Published: October 2002

The removal of toxic copper(II) from aqueous solutions was investigated using limestone fines (LS), which are inexpensive and widespread over the globe, as the effective inorganic sorbent with oleic acid (HOL) as the surfactant. The main parameters (i.e. initial solution pH, sorbent, surfactant and copper concentrations, stirring times, temperature and presence of foreign ions) influencing the sorption and flotation processes were examined. The results obtained showed the removal of more than 98% CuII at pH 7. It was also found that the addition of sodium and magnesium ions as activators enhanced the efficiency of copper separation. The procedure was successfully applied to recover copper spiked to some natural water samples. A mechanism for sorption and flotation is suggested.
Adsorbent Materials for Carbon Dioxide
Authors: Zou Yong , Rodrigues Alírio E.
Published: October 2002

The adsorption of carbon dioxide on adsorbent materials at high temperatures was critically reviewed. The present status of adsorbent materials for CO2 including carbon-based adsorbents, zeolites and metal oxide sorbents at high temperatures were discussed in detail. Research areas that may make a significant impact on the future development of adsorbent materials were advanced.
Use of the Lattice Model for the Description of Adsorption Isotherms of Organic Substances from Aqueous Solution
Authors: Kutarov V.V. , Kats B.M.
Published: October 2002

A novel equation for describing Langmuir-type adsorption isotherms was suggested. This equation satisfies the asymptotic limit, being converted into the Freundlich or Langmuir equations in the extreme cases. The equation also provides a description of the intermediate concentration range. Application of the suggested equation was demonstrated by calculation of the adsorption isotherms of aniline, benzoic acid, o-cresol, phenol, p-chlorophenol, 3,4-dichlorophenol and 2,4,6-trichlorophenol on various types of active carbon.
Applications of Gas Separation by Adsorption for the Future
Authors: Sircar S.
Published: October 2002

The separation and purification of gas mixtures by adsorption has found numerous industrial applications during the past 30 years. The very active research and development in this field is driven by (a) the highly flexible nature of cyclic adsorptive process designs, (b) the availability of many adsorbents for the separation and (c) the multiple choice of adsorbent–process design combinations for achieving the desired separation goals. The trend is to improve the product quality and separation efficiency, as well as to increase the scale of application of this technology. The design of processes using faster cycles and the use of innovative adsorber configurations are two new directions. Hybrid gas separation and production concepts such as adsorbent membranes and simultaneous sorption–reaction schemes are emerging areas that may open new frontiers of application for this technology.
Adsorption of Volatile Organic Compounds in Nitrogen Streams on Oxidized Activated Carbon Fibres
Authors: Kang Feiyu , Huang Zheng-Hong , Liang Kai-Ming , Yang Jun-Bing , Wu Hui
Published: October 2002

Viscose rayon-based activated carbon fibres (ACFs) with low and high specific surface areas were treated with conc. HNO3, 30 wt% H2O2 and air at different temperatures. The pore textures and surface chemistries of the samples were characterized by nitrogen adsorption at 77 K and X-ray photoelectron spectroscopic (XPS) methods. The adsorption of traces of volatile organic compounds (VOCs), i.e. benzene and methyl ethyl ketone (MEK), in nitrogen streams on the samples wwa measured by a gravimetric method. The results showed that the surface oxygen complexes and pore textures of all the oxidized ACFs were modified and differed depending on whether oxidation had been conducted under gaseous or solution conditions. ACFs with different specific surface areas possessed different adsorption characteristics towards VOC vapours after subjection to oxidation treatment.
Studies of the Accelerating Effect of Thiourea on the Reduction of ZnII in Mixed Water–Organic Solvents at the Mercury Electrode
Authors: Marczewska B.
Published: October 2002

The accelerating influence of thiourea on the ZnII/Zn(Hg) reduction process was investigated in the following mixed solutions: water–methanol (MeOH); water–ethanol (EtOH); water–dimethyl sulphoxide (DMSO); water–dimethylformamide (DMF). It was suggested that the dominant role in acceleration of the electrode process is played by the composition of the activated complex, which is presumably composed of solvent molecules and thiourea molecules adsorbed on to the electrode. A mechanism was proposed for the process occurring.
Nickel-Promoted Catalysts in the Reforming of n-Butane with CO2 or H2O
Authors: Pańczyk Monika , Giecko Grzegorz , Gac Wojciech , Pasieczna Sylwia , Stasińska Beata , Borowiecki Tadeusz
Published: October 2002

Studies of the reforming of n-butane by steam and carbon dioxide have been undertaken employing commercial catalysts such as Ni/α-Al2O3 modified by small additions of promoters such as K, Ba, Ce, W and Mo compounds. It was found that promoters improved the resistance of the catalyst towards coking, with this effect being smaller where CO2 was employed in the reforming reaction than when steam was used. The dynamics of the growth of the carbon deposit on the catalyst surface depended on the promoters employed as well as on the operating conditions; however, in the CO2 reforming of n-butane, such coking was more pronounced than in steam reforming. Use of the TPO method with oxygen or CO2 did not reveal considerable differences between the coke deposits formed during the reforming of n-butane with CO2 or H2O on the catalysts examined.
The Use of Human Hair Waste as a Phenol Biosorbent
Authors: Banat Fawzi A. , Al-Asheh Sameer
Published: October 2002

Human hair waste was tested as an adsorbent for the removal of phenol from aqueous solutions. Batch experiments were carried out to determine the effects of contact time, adsorbent concentration, initial pH, temperature and salt addition on this adsorption process. It was found that the uptake of phenol was virtually complete after 1 h. Up to 92% phenol removal was achieved at an initial phenol concentration of 60 ppm. The initial pH of the solution had a strong effect on the uptake of phenol and increasing the measurement temperature also increased the uptake. The presence of NaCl salt in the adsorption system had only a marginal effect on phenol adsorption.
Chars and Activated Carbons Prepared from Asturian Apple Pulp
Authors: Fernandez E. , Centeno T.A. , Stoeckli F.
Published: October 2002

Asturian apple pulp was carbonised under nitrogen at 400°C and 750°C and subsequently activated with CO2 at 750°C. The resulting active carbon exhibited properties in line with those expected from precursors of vegetable origin, with the carbonisation stage appearing to have only a limited influence on the final porosity. In the case of carbonisation at 400°C, the initial micropore system of the char was accessible to dichloromethane, CO2 and water, but presented a strong gate effect at ca. 0.35–0.40 nm. The pore volume, W0, was equal to 0.13 cm3/g and the average pore width 0.70 nm. The pore size distribution was obtained from CO2 adsorption at 0°C, using isotherms derived from computer modelling. With the char prepared at 750°C, the initial porosity was only accessible to water and its presence was confirmed by extrapolation of W0 for the activated carbons.
Physicochemical and Catalytic Properties of Vanadia/Titania Catalysts. III. Acidic Properties
Authors: El-Nabarawy Th. , Alaya M.N. , Ahmed S.A. Sayed , Youssef A.M.
Published: October 2002

FT-IR spectral studies of titania calcined at 400°C or 600°C indicated the presence of four important absorption bands with maxima located at 1630, 2920, 3670 and 3740 cm−1, respectively. These absorption bands have been ascribed to undissociated, coordinated water, hydrogen-bonded OH, acidic OH and basic OH groups, respectively. For vanadia/titania samples containing 6 wt% and 12 wt% V2O5 calcined at 400°C or 600°C, the band at 1630 cm−1 still existed in the corresponding spectra whereas that at 2920 cm−1 disappeared, thereby indicating an interaction between the vanadia and the hydrogen-bonded OH groups.

The FT-IR spectra of pyridine adsorbed on to titania or titania/vanadia samples exhibited bands at 1420 cm−1 and 1540 cm−1, respectively, the former being ascribed to Lewis acidity and exhibiting a shift to lower wavenumbers with increasing vanadia content, while the latter was ascribed to the presence of Brönsted acid sites.

Temperature programmed desorption (TPD) of pyridine from titania exhibited three desorption peaks extending over the temperature ranges 267–288°C, 335–370°C and 480–510°C, respectively. Impregnation of the initial titania samples with vanadia led to an increase in both the amount of acid sites present on the surfaces of the samples and in the acid strength. Besides reacting with Brönsted and Lewis acid sites, pyridine also underwent hydrogen bonding, with the hydrogen atom serving as a bridge between two electronegative nitrogen atoms.
Chromate Anion Adsorption on Iron Hydroxide
Authors: Mustafa S. , Jamal A. , Naeem A. , Rehana N.
Published: October 2002

Chromate anion adsorption on iron hydroxide was studied as a function of pH (3–9) and temperature (20–40°C). The adsorption of chromate anion was found to decrease with increasing pH and increase with increasing temperature. The data were explained with the help of the Kurbatov and modified Langmuir equations. The small effect of temperature indicated that chromate anion adsorption on iron hydroxide occurred through a mechanism involving outer - surface sphere complexation.
Sorptive–Flotation of Copper(II) from Water Using Different Types of Powdered Activated Carbons as Sorbents and Oleic Acid as Surfactant
Authors: Ghazy S.E. , Samra S.E. , El-Morsy S.M.
Published: October 2002

Different types of powdered activated carbon, viz. charcoal (PACh), graphite (PG) and three samples (PACI, PACII and PACIII) prepared from olive stones generated as plant wastes and modified with aqueous oxidizing agents, viz. H2O2, HNO3 and (NH4)2S2O8, were separated from aqueous solution by flotation using oleic acid (HOL) as a surfactant. The effects of initial temperature, initial pH of the suspension, initial carbon and surfactant concentrations, stirring times and the presence of foreign ions on the flotation efficiency of the carbon samples were investigated. Under optimum conditions, separation of the carbon samples was almost complete (~100%).

The separation of CuII-loaded carbon was also examined in the presence and absence of sulphide ions as activators. Nearly 100% CuII was removed at pH 7 after stirring for 30 min or on raising the temperature of the solution to 30°C or higher. In addition, CuII may be separated quantitatively at pH 3 and room temperature if sulphide ions are used as activators. The procedure was extended to the recovery of CuII added to some natural water samples. On the basis of IR analyses and neutralization titrations of the surface groups, a mechanism for the sorption and flotation processes is advanced.
Adsorptive and Membrane-Type Separations: A Bibliographical Update (2000)
Authors: Ray Martyn S.
Published: October 2002

This paper continues a series of annual bibliographic updates (data from 1985) of the published literature on selected particulate processes (see Ray 1990–2000). It provides a useful and quick reference source to the journal literature for the year 2000 (taken from the 50 most important chemical engineering journals) for researchers in this area. The references included here have been divided into the following subject groups: theory, design data, adsorbents, PSA and cyclic systems and applications, liquid-phase adsorption ion exchange, chromatography and related separations, membranes and membrane-type separations.

Adsorption and related separations for industrial and environmental applications are described in detail in Dabrowski (1999) which also contains extensive bibliographies prepared by this author. A complete bibliographic listing of the chemical engineering journal literature from 1959 to 2000 (with subsequent six-monthly updates) is available on a CD-ROM database*. Full details are available from www.rmitpublishing.com.au , or the author (MSR).
Expansion and Contraction of Variable Rank Coals during the Exchange Sorption of CO2 and CH4
Authors: Ceglarska-Stefańska Grażyna , Zarębska Katarzyna
Published: October 2002

The influence of the physical and chemical properties and the composition of the sorbed gas on the sorption capacity of hard coal must be taken into account in an analysis of such coals as specific collectors of mine gases. The analysis presented was based on a comparison of the results of sorption and expansion studies of single gases (CO2 and CH4) and their mixtures on two hard coals (Vdaf: 40.87% and 22.32%). The work presented was undertaken in an attempt to determine the influence of the sorptive deformation of the coals, caused by the pre-sorption of CO2, on the variation of their external dimensions during CH4 sorption and vice versa, and during sorption of a mixture of these gases. In addition, it was anticipated that the work could answer the question as to which of these gases would enrich the desorbed gas. Knowledge of these effects should facilitate further exploration of the relationship between the properties of a hard coal and methane evolution to establish those factors that enhance the rate and effectiveness of the process.
Non-linear Free Vibration of Single-layer Reticulated Shallow Spherical Shells
Authors: Nie G. H.
Published: October 2002

This paper presents an asymptotic analysis on non-linear free vibrations of single-layer reticulated shallow spherical shells composed of beam members placed in two orthogonal directions with the aid of a continuum model proposed by the author. By introducing a parameter variable which is determined by solving a cubic single-variable equation for the case of axisymmetry, the fundamental governing equations can be exactly satisfied. The asymptotic iteration method has been adopted to obtain an analytical solution for a non-linear characteristic relation between the amplitude and frequency of the structure. Numerical examples are given, and the phenomena indicating softening and hardening of such structures have been presented for various values of radius of curvature (or apex rise) of hinged or clamped spherical shells.
Limit-State Analysis and Design of Cable-Tensioned Structures
Authors: Liew J. Y. Richard , Punniyakotty N. M. , Shanmugam N. E.
Published: October 2002

This paper deals with application of nonlinear analysis to study the system's limit state behaviour of cable-tensioned steel structures. The cable tendon is modelled as an equivalent truss element with initial pretensioned force applied either as self-equilibrating axial load or as an equivalent thermal load. The modulus of elasticity of the cable material can be modified to account for the constructional stretch and sagging effects in the cables. Pin-jointed space truss systems are modelled using a plastic-hinge nonlinear formulation, which implicitly satisfies the design specifications for ultimate strength of axially loaded members. Rigid space frame systems are modelled using an elasto-plastic nonlinear frame analysis program. The effectiveness of providing pretensioned cables in improving the limit state behaviour of pin-and rigid-connected space frames is demonstrated through several examples.
Formex Configuration Processing II
Authors: Nooshin Hoshyar , Disney Peter
Published: October 2002

This is the second paper in a series of papers that are intended to provide a comprehensive coverage of the concepts of formex configuration processing and their applications in relation to structural configurations. In the present paper, attention is focused on the configuration processing for a number of families of space structures, namely, pyramidal forms, towers, foldable systems and diamatic domes. Also included is a section on information export as well as an Appendix on basic formex functions. The section on information export describes the manner in which the information about the details of a configuration, generated by the programming language Formian, can be exported to graphics, draughting and structural analysis packages.
Wind-Induced Response Analysis and Wind-Resistant Design of Hyperbolic Paraboloid Cable Net Structures
Authors: Shen Shizhao , Yang Qingshan
Published: October 2002

Cable net structures, as a kind of light and flexible structures are very sensitive to wind excitations. The wind-induced response analysis and wind-resistant design are studied systematically in this paper. The main subjects studied are as follows: (1) the fundamental equations of cable structures; (2) a method for displacement response analysis of cable structures; (3) the formulae for computing inner forces in cable elements; (4) the expression of dynamic coefficients for displacement and inner force of cable structures as a geometrically nonlinear system; (5) numerical parameter analysis of H. P. cable net structures and the determination of dynamic coefficients.
A General Finite Element Approach to the form Finding of Tensile Structures by the Updated Reference Strategy
Authors: Bletzinger Kai-Uwe , Ramm Ekkehard
Published: October 2002

Starting from a rigorous mechanical formulation, a numerical procedure is developed for the form finding of minimal surfaces and pre-stressed membrane structures. The method is based on an iteratively adapted regularisation of the stiffness matrix which gives the method its name: the updated reference strategy. The method can be applied to any finite element discretization of cable and membrane structures subjected to pre-stress as well as lateral pressure or other external loading. It is very robust and reliable as is shown by many illustrative examples. Further analysis states that the well known force density method is the special case of applying the updated reference strategy to cable nets.
Structural Assessment and Quality Control Procedures for the Homa Aircraft Hangar No.3
Authors: Maalek Shahrokh
Published: October 2002

Through the explanation of the methodology employed in the structural assessment and quality control of Homa aircraft hangar No. 3, some technical information has been presented which can be extended to a class of space structures: those with tubular members and socket type joints. An experimental programme of work has been conducted involving load tests on a number of tubular members with forged ends, double tubular sections and socket joints, designed and manufactured to be used as the structural components of the triple layer space grid system. The main potential deficiencies observed included: (i) local buckling, premature yielding and end straightening at the positions of the forged ends of tubular members, (ii) bolt stripping at the bolted connections of the end cones, and (iii) excessive deformation of socket joints. The manner in which such deficiencies were treated, has also been reported. A simple detail has been suggested which makes it possible to provide effective double tubular sections, using intermediate filler rings. Problems associated with the construction and erection of the roof system have been discussed. An automated reanalysis-redesign process has been adopted and a series of analyses have been carried out to investigate the possibility of progressive collapse. A nonlinear analysis approach for the consideration of joint flexibility has been introduced briefly.
Compliant Blades for Passive Power Control of Wind Turbines
Authors: Lee A.T. , Flay R.G.J.
Published: October 2002

Recent advances in analysis capabilities for wind turbine blade aerodynamics and structural dynamics enables a thorough understanding of the connection between the aerodynamic excitation and structural response of blades. By designing the blades using fibre reinforced composite materials, coupling between bending and torsion, for example, can be built-in. In the present work the objective was to investigate the capability of a 50 kW constant speed wind turbine to automatically shed power in gusts by feathering the blades, i.e. twisting them towards the relative wind vector thus reducing the angle of attack, whilst bending away from the wind. This numerical study demonstrated that it is difficult to achieve constant power output with compliant blades for a fixed speed wind turbine because a large amount of twist is required. This paper details the investigation and results obtained in this aeroelastic study of compliant blades made from fibre reinforced composite materials.
Power Variation Control of a Wind Turbine Generator Using Probabilistic Optimal Control, Including Feed-Forward Control from Wind Speed
Authors: Kodama Naruhito , Matsuzaka Tomoyuki , Inomata Noboru
Published: October 2002

The 500kW wind generator was developed as one of the projects of NEDO (New Energy and Industrial Technology Development Organisation in Japan), and several tests on its performance have been made. Based on the measurement data, we modelled the NEDO 500kW wind generator(1),(2), and have investigated a method to reduce power variations under fluctuating wind conditions. This paper presents a control strategy based on a probabilistic optimal control scheme, and makes comparisons between power variations with the conventional PID controller and with the proposed controller. The result showed that the proposed controller could reduce the covariance of power variations to approximately one third.
Experimental Study of Wind Turbine Blade Power Augmentation Using Airfoil Flaps, Including the Gurney Flap
Authors: Bao Nengsheng , Ma Haoming , Ye Zhiquan
Published: October 2002

The purpose of this paper is to present the feasibility experiment study of the power and efficiency augmentation of the horizontal axis wind turbine system by adding small flaps to its blades. The experiment of lift enhancement of a two-dimensional airfoil with a small trailing edge flap is conducted in a low-speed, closed-loop wind tunnel at Shantou University. NACA 632–215 is selected as the tested airfoil and the Reynolds number is 2.4×105, based on airfoil chord. In experiments the angles of attack varied from 0° to 40° and the heights of the flaps are 1.0%, 1.5%, 2.0% and 2.5% of the airfoil chord. The effects of different deflection angles (0°, 45°, 90°, 135°) of the trailing edge flap are compared. The lift and drag coefficients are determined from the surface pressure distributions, which were measured for all tested conditions. The results indicate that all tested flaps could increase the lift coefficient and the larger flaps produce successively larger increments, although not proportionally. The Gurney flap shows a superior performance compared with other angles trailing edge flaps.
Wind Speed Power Spectrum Analysis for Bushland, Texas, USA
Authors: Eggleston Eric D. , Clark R. Nolan
Published: October 2002

Numerous papers and publications on wind turbulence have referenced the wind speed spectrum presented by Isaac Van der Hoven in his article entitled Power Spectrum of Horizontal Wind Speed Spectrum in the Frequency Range from 0.0007 to 900 Cycles per Hour (Journal of Meteorology, Vol. 14, 1957, p. 160). Van der Hoven used data measured at different heights between 91 and 125 meters, and represented the high frequency end of the spectrum with data from the peak wind speed hour of hurricane Connie (13 August 1955). Because the data were collected in such special conditions we should question the use of his power spectrum in the wind industry. We computed a power spectrum for Bushland, Texas, from 13 years of hourly average data, 1 year of 5 minute average data, and 2 particularly gusty day's 1 second average data all collected at a height of 10 metres. While the general shape is similar to the Van der Hoven spectrum, few of his peaks were found in the Bushland spectrum.
International Iee School on Embedded Generation
Authors: Jung Juliane
Published: October 2002

Organised by the Institute of Electrical Engineers, in association with the British Wind Energy Association (BWEA), the Association of Electricity Producers (AEP) and the Institute of Mechanical Engineers (I Mech E)
Systematic Controller Design Methodology for Variable-Speed Wind Turbines
Authors: Hand M. Maureen , Balas Mark J.
Published: October 2002

Variable-speed, horizontal axis wind turbines use blade-pitch control to meet specified objectives for three regions of operation. This paper provides a guide for controller design for the constant power production regime. A simple, rigid, non-linear turbine model was used to systematically perform trade-off studies between two performance metrics. Minimization of both the deviation of the rotor speed from the desired speed and the motion of the actuator is desired. The robust nature of the proportional-integral-derivative controller is illustrated, and optimal operating conditions are determined. Because numerous simulation runs may be completed in a short time, the relationship between the two opposing metrics is easily visualized.

Traditional controller design generally consists of linearizing a model about an operating point. This step was taken for two different operating points, and the systematic design approach was used. The surfaces generated by the systematic design approach using the two linear models are similar to those generated using the non-linear model. The gain values selected using either linear model-based design are similar to those selected using the non-linear model-based design. The linearization point selection does, however, affect the turbine performance. Inclusion of complex dynamics in the simulation may exacerbate the small differences evident in this study. Thus, knowledge of the design variation due to linearization point selection is important.
Useful Computer Codes for Wind Energy Engineering Applications
Authors: Manwell James F. , Rogers Anthony L. , McGowan Jon G.
Published: October 2002

At the University of Massachusetts a number of wind engineering computer codes (the “UMass Mini-Codes”) have been developed during the past for educational, research, and design purposes. The purpose of this paper is to present an overview of these codes. A summary description of each of these codes (categorized by groups: data analysis, data synthesis, rotor aerodynamics, electrical, dynamics, and turbine/system performance) is given which contains the overall methods employed, underlying algorithms, and appropriate references. It is expected that these codes will be used for educational purposes, or for general use by the wind energy engineering community.
Assessment of a Wind Turbine Intelligent Controller for Enhanced Energy Production and Pollution Reduction
Authors: Spiegel Ronald J.
Published: October 2002

This study assessed the enhanced energy production which is possible when variable-speed wind turbines are electronically controlled by an intelligent controller for efficiency optimization and performance improvement. The control system consists of three fuzzy-logic controllers: a controller to track the turbine generator speed with wind speed to extract maximum output power; a controller to optimize the generator airgap flux for efficiency improvement; and a controller to provide robust speed control against wind gusts and oscillatory torque. The paper describes the control system which has been developed; pertinent laboratory-based results; and an estimate of the enhanced energy production that is possible when the device is installed on a wind turbine. Additionally, the overall enhanced wind energy potential for the USA as a whole is provided if this type of controller is widely installed on turbines in the future. Enhanced pollution offsets are given as based on the increased energy production possible with the controller.
Suggestions for Improving Wind Turbines Blade Characteristics
Authors: Fupeng Huo , Yuhong Li , Zuoyi Chen
Published: October 2002

Suggestions for improving the efficiency and life expectancy of wind turbine blades are proposed in this paper. A new airfoil shape with wide leading edge nose and large camber has been investigated by numerical simulation with a range of attack angles. The results show that the lift-drag ratio of the airfoil is greater than that of the conventional airfoil at large attack angles (α>20°). Changing the local roughness on blade surfaces to improve the wind turbine performance is discussed in the paper. A new mechanism and method of analysing life expectancy of a blade with flow induced vibration in oscillating flow has been given. It is proved that the damping of blade material and structure has great influence on the endurance lifetime of blades. The investigation indicates further that the equilibrium amplitude of vibration greatly influences the lifetime of blades. Changing the damping characteristic of a blade may significantly vary its equilibrium amplitude, so extending the life expectancy of blades. This paper provides the foundations for further study.
Wind Data Analysis and a Case Study of Wind Power Generation in Hong Kong
Authors: Lu Lin , Yang Hongxing
Published: October 2002

This paper analyses wind speed data for five typical sites in Hong Kong in terms of site terrain, wind conditions and wind power potential. For onshore and offshore wind power resources, the annual, monthly and diurnal wind speeds are assessed, and the annual mean power densities for the five sites are also calculated. These may be used for optimum sitting of wind sites in Hong Kong, which is also discussed for practical application. The characteristics and power output of a chosen wind turbine on one island are modelled and analysed as a case study to assess the wind power potential. The capacity factor of the modelled wind turbine reaches nearly 0.36, which is considered significant for wind power application. The example demonstrates that the sites on islands with good exposure are attractive for generating wind power, and that therefore offshore should be considered.
The Dynamic Performance of a Composite Blade from a 5kW Wind Turbine. Part 1: Measured Blade Response
Authors: Bechly M. E. , Clausen P. D.
Published: October 2002

This paper presents and considers dynamic structural measurements from the blade of an operating 5 kW wind turbine. One of the turbine's 2.5m long composite blades was instrumented with strain gauges at several locations along its length with signals acquired through a novel capacitive coupling device to a stationary computer. Data were acquired from the blade and from strain gauges measuring torque on the main shaft in azimuthal mode at 8 times per revolution, and otherwise in the time domain at a fixed rate of 200 Hz. Simultaneous with these measurements, analog signals from wind speed, wind direction, turbine direction, turbine speed, temperature and battery charging power were sampled at least once per revolution. The results from two situations, where the wind speed was approximately the same but the turbine operating conditions were measurably different, were considered in detail. A Fourier transform of the signals from the blade flapwise gauges show a dominant once per revolution load and smaller twice and three times per revolution loads. Fourier transform of signals from the torque gauges show a dominant once per revolution load for a high turbine speed case, but not for a lower speed case. Loads from a gearbox fault, with a frequency corresponding to the gear ratios from the dual stage gearbox are evident in both cases. Root flapwise bending moments and lead-lag bending moments show a skewed once per revolution sinusoidal response with some evidence of higher order components in the results from the low-speed case. The unusual twist section in the blade shape has lead to coupling between flapping and lead-lag motions, which has influenced the blades azimuthal response. A second paper, part II, is planned with further analysis.
Structure Dynamic Analysis of a Horizontal Axis Wind Turbine System Using a Modal Analysis Method
Authors: Zhiquan Ye , Haomin Ma , Nengsheng Bao , Yan Chen , Kang Ding
Published: October 2002

This paper considers the structural dynamic analysis of horizontal axis wind turbine (HAWT) rotor blades. Initially a blade from a 300 W machine was used, using both experimental and theoretical modal analyses. In the experiments, a DAS (Dynamic Signal Analysis and Fault Diagnosis System) was used to extract modal parameters by measuring vibrations at various locations along the blade surface. A finite element analysis (FEA) method was used for the theoretical modal analysis. Comparison of experiment and theory explains the low order vibration conditions. The effects of different constraint conditions of the FE model are discussed. Finally, theoretical modal analysis is used to analyze a 600 kW rotor blade. The results are compared with those calculated using ‘Bladed for Windows’ of Garrad Hassan and Partners Ltd (UK), and satisfactory agreement between them is obtained.