bluuebunny/crossref_metadata_2025 huggingface dataset:
Generalised Disturbance Observer for Systems with Harmonic Disturbances and Input Saturation Using the Internal Model Principle
Authors: Kosaka Manabu , Uda Hiroshi
Published: August 2010

It is known that some rotational machines such as compressors, pumps and so on often generate noises and vibrations due to periodic disturbances synchronised with the rotational speed. Vibration suppressing systems such as repetitive control are known to be effective to suppress the periodic disturbances. However, the control input of the repetitive controller may become larger and larger when the control input is saturated. This paper designs a generalised disturbance observer using the internal model principle that is effective to suppress periodic disturbances, and proposes a method that can make control performance deterioration minimal even if the control inputs are saturated. First, the proposed system estimates disturbances using the disturbance observer. Next, the estimated disturbances are passed into a filter of which the gain is one and phase lag is zero at the disturbance's frequencies, and are added into the control input in order to cancel the periodic disturbance. This filter is designed using the internal model principle, and the reason is explained why the filter should not be set to one. Some motor system simulations show that the phase lag of the estimated disturbances correspond to that of the periodic disturbances so that the method can make control performance deterioration minimal. The method is appropriate to rotational machine systems such as compressors and pumps in which the vibrations and noises should be avoided.
Experimental Evaluation of Whole Body Vibration Exposure from Tracked Excavators with Hydraulic Breaker Attachment in Rock Breaking Operations
Authors: Alphin M.S. , Sankaranarayanasamy K. , Sivapirakasam S.P.
Published: August 2010

Ever expanding technological growth has led to an increase in the use of tracked excavators for construction, demolition, material handling, rock breaking etc. Excavator operators are exposed to a variety of risk factors that may lead to health problems. A major health hazard among operators is whole-body vibration. Human response to vibration is very complex and nonlinear. Whole Body Vibration in the range of 2 to 30 Hz corresponds to most of the resonant responses of various organs and parts of the human body. The objective of this paper is to assess whole body vibration for the tracked excavator with hydraulic breaker. The job safety analysis conducted through questionnaires for different industrial vehicle operators revealed the presence of a health risk among the operators in rock breaking machinery. To quantify the level of vibration, field tests are performed on four tracked excavators with hydraulic breaker attachments in two different work locations. Accelerometer, a real-time signal conditioning / processing and PULSE data acquisition software are used for vibration measurement. The frequency of vibration exposure is observed to be between 6.8 and 12 Hz. Acceleration levels measured were in the range of 0.87 −2.2 m/s2 for a tracked excavator operator with breaker. The total vibration exposure calculated was between 0.621 and 1.932 m/s2. The vibration dose value recorded was 17.6 −62.72 m/s1.75. Whole body vibration exposure of the breaker operator was much higher and lies beyond the upper limit as given in ISO 2631–1. The ranges of vibration parameters measured were concomitant with frequent lower back pain, other muscular-skeletal injuries like leg pain etc which are prevalent among these operators.
Active Noise Control as a Solution to Low Frequency Noise Problems
Authors: Wise Steve , Leventhall Geoff
Published: August 2010

The control of low frequency noise presents special problems which do not occur at higher frequencies. These problems relate mainly to the long wavelength at low frequencies, which leads to little absorption by conventional means, unless large quantities of absorbing material or large volumes of space are used. There are many examples of low frequency noise problems which can be solved by active attenuation, without the use of thick absorbing material. Some of these are given in this paper.
Auditory Masking of Low-Frequency Sound and the Relation between Masking Characteristic and Psychological Response
Authors: Watanabe Toshio , Yamada Sinji
Published: August 2010

The auditory masking of low-frequency sound by pure tones and band noise was measured. Forty subjects participated in our experiments. There was not much variation among the subjects in the masking by pure tones but there was a large variation among them in the masking by band noise. The masking characteristics of band noise were investigated. The frequency characteristics of the masking by band noise could be divided into three groups of subjects by cluster analysis. The first group of subjects had masking values that were positive or small at all frequencies. The second had masking values that were negative or small at several frequencies. The third had masking values that were positive at frequencies lower than 20 Hz and negative at frequencies greater than 20 Hz; the curve of these values having an inverse S shape. To find the reason as to why the subjects could be divided into a few groups according to the masking characteristic, psychological experiments were performed. Twenty-one sound stimuli, – pure tone, band noise and both pure tone and band noise – were prepared. The subjects belonging to a particular group had similar psychological responses to the sound stimuli. Many people do not complain about low-frequency sound but some people are suffering from it. The people who sensitively responded to low-frequency sounds are reported. The results obtained here may explain the special relationship between the sufferers from low-frequency sound and the hearing characteristic.
Identification of Complex Sound Source by the Phase Conjugation Method
Authors: Liu Song , Li Sheng , Zhao Deyou
Published: August 2010

The phase conjugation method has been used for the identification and reconstruction of complex sources. A plate subject to a point force and a pulsating cube are involved to verify the effectiveness of the method. The surface pressure, the surface normal velocity, the radiation power, and the intensity are reconstructed with different phase conjugation arrays. Numerical results show that the best identification results could be achieved by an array made of dipole transceivers based on pressure gradient measurements in the near field. Phase conjugation arrays achieve a very high resolution to identify the surface pressure and normal velocity and reconstruct the radiation power and the intensity very well. The phase conjugation method for identification and localization of the radiated field has advantages of posing no difficulties and using a small number of measurements and it is natural to use patch method. These features may make the phase conjugation method a powerful noise diagnostic tool. For an array in the far field only the location of the maximum pressure response could be identified.
Characterization of Manganese Oxide and the Adsorption of Copper(II) and Lead(II) Ions from Aqueous Solutions
Authors: Zou Weihua , Zhang Jinghua , Li Ke , Han Pan , Han Runping
Published: August 2010

The characterization and sorption properties of manganese oxide towards Cu(II) and Pb(II) ions from aqueous solution were investigated. Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared (IR) analyses were used to characterize the manganese oxide.

Parameters affecting the adsorption of Cu(II) and Pb(II) ions, such as the adsorbent dosage, the ionic strength of the solution, the contact time, the solution pH, the initial metal ion concentration and the temperature, were investigated. The binding of Cu(II) and Pb(II) ions to manganese oxide was highly dependent on the pH of the solution, with the extent of adsorption increasing as the pH of the system increased. The uptake of both Cu(II) and Pb(II) ions was found to increase with temperature. Furthermore, the removal efficiency of Cu(II) and Pb(II) ions from aqueous solution increased with increasing adsorbent dosage and decreased with ionic strength.

The adsorption equilibrium and adsorption kinetics of Cu(II) and Pb(II) ions onto manganese oxide were studied. The adsorption process was spontaneous and exothermic, with the order of affinity being Pb(II) > Cu(II). The same behaviour was observed during competitive adsorption, viz. adsorption from a binary solution of the ions concerned.
Phosphate Ion Removal from Aqueous Solution Using an Iron Oxide-Coated Fly Ash Adsorbent
Authors: Yao Shuhua , Li Jinyan , Shi Zhongliang
Published: August 2010

The ability of an iron oxide/fly ash composite adsorbent prepared with municipal solid waste fly ash and iron nitrate to remove phosphate ions from aqueous solutions has been tested. The characteristics and physicochemical performances of the composite were investigated via nitrogen adsorption and scanning electron microscopy (SEM) studies. The comparative adsorption of phosphate ions by the composite adsorbent and fly ash was investigated using batch experiments.

It was found that the adsorption properties of the composite adsorbent towards phosphate ions depended on the pH value of the solution and the anion concentration in the same. The equilibrium data were analyzed using the Langmuir and Freundlich isotherms, from which it was shown that the adsorption capacities for phosphate ions at pH 3.0 were 27.39 mg/g for iron oxide/fly ash and 18.90 mg/g for fly ash. The results showed the adsorption patterns for phosphate ions with fly ash and iron oxide/fly ash composite adsorbent showed a better match to the Freundlich model rather than the Langmuir model. The adsorption kinetic data could be well described by the Lagergren pseudo-second-order kinetic equation. The effect of temperature on the adsorption phenomena was investigated, the results indicating that phosphate ion removal by iron oxide/fly ash composite adsorbent was endothermic in nature.
Removal of Chromium(VI) Ions from Aqueous Solutions and Industrial Effluents Using Magnetic Fe3O4 Nano-particles
Authors: Begum K.M. Meera Sheriffa , Anantharaman N.
Published: August 2010

The adsorption characteristics of magnetic Fe3O4 nano-particles synthesized by chemical co-precipitation for the removal of chromium(VI) ions from aqueous solutions and tannery effluents have been studied. The composition, size, morphology and magnetic properties of the nano-particles were characterized by FT-IR, XRD, TEM and VSM methods, respectively. Experiments were conducted in batch mode to observe the influence of different parameters such as pH, feed concentration, adsorbent dosage and temperature on the performance of the adsorbent.

It was found that when the pH of the system was decreased from 7 to 2, the extent to which Cr(VI) ions were removed increased from 54% to 77%. The adsorption process was found to follow second-order kinetics and the rate constant was evaluated at 30 °C. The Langmuir isotherm was found to provide a good fit to the experimental data. The adsorption capacity of magnetite nano-particles towards Cr(VI) ions at room temperature was 2.9508 mg/g, with the value increasing to 3.4454, 3.7592 and 4.0475 mg/g at 40 °C, 50 °C and 60 °C, respectively. On the basis of the adsorption free energy change of 16.577 kJ/mol obtained at 30 °C, the adsorption mechanism was confirmed as being chemical in nature. The thermodynamic parameters for the adsorption process were also calculated from the experimental data. At an S/L ratio of 0.2 and under optimized conditions of pH, temperature and agitation, the removal of Cr(VI) ions from aqueous solution amounted to 85%. Regression analysis was performed and a correlation between percentage removal and operating parameters obtained.
Functional Groups and Interactions Controlling the Adsorption of Bisphenol a onto Different Polymers
Authors: Yang Weiben , Ren Li
Published: August 2010

The behaviour of different polymers in the adsorption and removal of bisphenol A (BPA) from aqueous solutions was examined in order to identify the mechanism controlling the process. Three polymers with different functional groups were prepared and employed in our laboratory; they were characterized both texturally and chemically in terms of their surface areas, pore-size distributions, total exchange capacities and other parameters. The adsorption isotherms of bisphenol A were obtained and accurately modelled by the three-parameter Langmuir–Freundlich (LF) isotherm, the binding parameters calculated directly by the LF fitting coefficients indicating that increasing temperature was helpful in causing the adsorption process to move from positive cooperativity to negative cooperativity.

The kinetic data were found to be well represented by the pseudo-second-order kinetic model, indicating that the functional groups of the polymers had a significant influence on the adsorption mechanism of BPA. The adsorption of BPA basically depended on the chemical nature of the polymers and the pH value of the solution. The adsorption process was favoured by the molecular form of bisphenol A, since this controlled the surface complexes produced between the polymer surface and the bisphenol A molecules, with the resulting increase in adsorbent–adsorbate interactions being positively influenced by the temperature.
Triple Point of a Lennard-Jones Fluid in Nanopores with Zero Excess Pore Wall Energy
Authors: Kanda Hideki , Miyahara Minoru
Published: August 2010

We have examined the triple points of Lennard-Jones methane confined in slit-shaped nanopores, i.e. nanopores with zero excess potential energy, using a molecular dynamics technique developed by us in a previous study. The critical condensates in the pores were cooled in a stepwise manner and the triple points determined for different pore sizes. We observed that the triple point temperature was inversely related to the pore size, identical to the Gibbs–Thomson equation. Whilst the Gibbs–Thomson equation requires adjustable parameters, our triple point model could predict the pressure and temperature without the need for such parameters. As a consequence, our model demonstrates a higher degree of generalization than the Gibbs–Thomson equation.
Adsorption of Pb2+ and Ni2+ Ions by Montmorillonite: Isotherm, Kinetic and Thermodynamic Studies
Authors: Miao Deren , Liu Fei , Liu Yulong , Chen Honghan
Published: August 2010

The adsorption of Pb2+ and Ni2+ ions from aqueous solution onto montmorillonite (MMT) has been investigated at 293 K, 303 K, 313 K and 323 K using batch equilibrium experiments. In order to optimize the adsorption conditions, the effects of contact time, solution pH and initial metal ion concentrations were tested thoroughly. The adsorption isotherms were best described by the Langmuir model at lower temperatures, while the Freundlich model gave a better fit at higher temperatures. The theoretical saturated adsorption capacities of MMT for Pb2+ and Ni2+ ions at 293 K as calculated via the Langmuir isotherm were 133 g/kg and 56 g/kg, respectively. The kinetic data were poorly correlated by the pseudo-first-order model and the intraparticle diffusion equation, but were fitted perfectly by the pseudo-second-order kinetic model. For Pb2+ ions, the thermodynamic parameters ΔadsG0, ΔadsH0 and ΔadsS0 were determined as −3.08 kJ/mol (at 293 K), 4.83 kJ/mol and 26.95 J/(mol K), respectively. For Ni2+ ions, the values of ΔadsG0, ΔadsH0 and ΔadsS0 were −1.10 kJ/mol (at 293 K), 23.77 kJ/mol and 84.63 J/(mol K), respectively. The experimental results indicated that the adsorption processes for both Pb2+ and Ni2+ ions onto MMT were favourable, spontaneous and endothermic.
Novel Preparation and Physicochemical Characterization of a Nanocrystalline Cobalt Ferrite System
Authors: Deraz N.M. , El-Aiashy M.K. , Ali Suzan A.
Published: August 2010

Well-defined CoFe2O4 nanoparticles with an average grain size of about 50 nm were successfully synthesized by a combustion method employing different ratios of fuel to cations within the range 0–2.67. The as-prepared powders were characterized and investigated by TG, XRD, IR, SEM, TEM and VSM methods, and via isopropanol conversion at 250–450 °C.

The results showed that increasing the ratio between fuel and cations stimulated the formation of cobalt ferrite due to the increasing flame temperature. Changing the fuel/cation ratio brought about modifications in the structure, surface activity, selectivity and magnetic properties of the investigated solids. A fuel/cation ratio of 2 led to the formation of catalyst having a high activity (49%) and magnetization (77.54 emu/g). All the solids investigated behaved as dehydrogenation catalysts leading to the formation of acetone as the major product. The fuel/cation ratio did not alter the mechanism of dehydrogenation of isopropanol, but increased the concentration of active sites involved in the catalyzed reaction.
Kinetic Models of the Adsorption of Hexavalent Chromium by Chitosan from Aqueous Solution
Authors: Yan JinLong , Quan Guixiang
Published: August 2010

The batch removal of hexavalent chromium from aqueous solution by chitosan under different experimental conditions, such as the pH value and the initial hexavalent chromium ion concentration, was investigated. The adsorption of hexavalent chromium is highly pH-dependent, the results obtained in the present study indicating that the optimum pH for Cr(VI) ion removal was 4.0. The kinetics of the adsorption of Cr(VI) ions by chitosan were evaluated by the pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion kinetic models, respectively. The results show that the pseudo-second-order kinetic model gave a good correlation (r2 = 0.9942) with the experimental data.
Solophenyl Navy Blue Dye Removal by Smectite Clay in a Porous Bed Column
Authors: da Silva Gilson L. , Silva Valdinete L. , Vieira Melissa G. A. , da Silva Meuris G. C.
Published: August 2010

Many studies have been reported whose objective has been the removal of effluent dyes from aqueous solution via adsorption methods. Among the adsorbents studied have been natural clays. The present study was aimed at evaluating smectite clay as a viable adsorbent for the removal of dyes from wastewater in industrial textile laundries. This clay is mainly composed of residue generated in the activities related to the exploration of gypsite which is abundantly available in the Araripe–PE region, located in Northeast Brazil.

In the methodology chosen, a solution of the navy blue dye Solophenyl, which is the main dye employed in such laundries, was prepared with the following composition: 0.75 g dye + 11.25 g sodium chloride in 1000 mℓ of water. The clay (0.2 g quantity) was used in two forms: the natural extracted material and product obtained after its calcination at 300 °C. All assays were undertaken employing a porous bed column. The experimental data allowed an assessment of the kinetic behaviour of the dye, and of the removal capacity and removal efficiency of the examined clays. The maximum adsorption capacity was obtained with smectite clay calcined at 300 °C, being 10.36 mg Solophenyl dye per gram clay at an output rate of 3 mℓ/min. The results were adjusted to the Logistic function model available in Origin 6.1 software, when an excellent correlation was obtained with the experimental adsorption data.
On the Movement of Tensegrity Structures
Authors: Tur Josep M. Mirats
Published: August 2010

We study in this paper the feasibility of a moving tensegrity structure having some of its elements actuated. In this way two different approaches are presented. First, a realization of a tensegrity based robot composed of a 3-bar symmetric prism-like minimal tensegrity configuration is given. This first prototype has its lower nodes anchored to the ground. We provide a detailed implementation description of the physical robot, and analyse some trajectories within its workspace. Second, a simulator is presented in which, taking into account the structure dynamics, a tensegrity based mobile robot, hence not anchored, is capable of following a trajectory on a planar surface. This provides us a first insight of how these structures should be actuated and sensed in order to produce movement.
Direct Estimation of Critical Load for Single-Layer Reticulated Domes with Semi-Rigid Joints
Authors: Fan Feng , Ma Hui-Huan , Cao Zheng-Gang , Shen Shi-Zhao
Published: August 2010

Numerical model of a bolt-ball joint system is established using software ANSYS and verified through experiments. Based on the bendingrotation curves of the bolt-ball joints obtained through numerical simulation, a finite element model of single-layer reticulated domes with bolt-ball joint system is established using nonlinear beam element with end spring elements in software ANSYS. The analyses of the domes are carried out with different parameters including bending stiffness, ratio of rise to span, rotation-stiffness, ball size, asymmetric load distribution, tube section, support condition and initial imperfection. Several key parameters having influence on the load carrying capacity of a semi-rigidly jointed single-layer reticulated dome are thus identified. Finally, formulas are established for direct estimation of critical loads of semi-rigidly jointed single-layer reticulated domes under symmetric and asymmetric loading conditions.
Basic Study on Multi-Bay Horn-Shaped Membrane Roof
Authors: Nagai Yuki , Okada Akira , Miyasato Naoya , Saitoh Masao
Published: August 2010

Wind loading is the most dominant load for light-weight structures such as membrane roofs. Since the multi-bay horn-shaped membrane roof has a complicated shape and is composed of several horn-units depending on the building type, basic data for the wind-force coefficient has not been reported yet. On the other hand, the multi-bay horn-shaped membrane roof is usually designed using the structural behavior of a one-unit system. Furthermore, the authors consider that the design method must be changed not only according to size and building type but also supporting systems. From the view of these problems, in this paper, the wind-force coefficients for design and analysis are clarified by the wind-tunnel test, and a design method considering the influence of supporting systems under wind loading is proposed.
Shape Determination Problem of Spatial Cable-frame type of Suspended Single-layer Reticulated Shells with Free Surface
Authors: Zhang Zhi-Hong , Dong Shi-Lin
Published: August 2010

A novel spatial cable-frame type of suspended single-layer reticulated shells with free surface (Spatial cable frame plus single-layer reticulated shell with free surface) is proposed in the present paper. Shape determination problem of the lower cable-bar system of general hybrid spatial structures with free surface upper structure is also put forward and investigated. Shape determination problem in essence is one kind of calculus of variation problem. On the basis of the general inverse of equilibrium matrix of the lower cable-bar system and dynamic relaxation method an efficient numerical algorithm is also given out in details. This numerical algorithm is programmed by using VC++ 6.0 and is also validated by numerical examples. Hopefully the work in the present paper could benefit the further research work and practical engineering on general hybrid spatial structures.
“Tracing” the Equilibrium — Recent Advances in Numerical Form Finding
Authors: Linhard Johannes , Bletzinger Kai-Uwe
Published: August 2010

This paper explains the numerically and physically caused problems encountered in a computational form finding process of prestressed membrane structures and proposes effective stabilization techniques for the respective cases. The updated reference strategy (URS) is used to stabilize the problem of “floating meshes”, which is caused by the inverse nature of the discretized problem. The convergence of the resulting iterative solution can be effectively monitored with the help of a new error norm, which has been recently developed. It allows measuring the actual stress deviations by a simple to be used, scalar, dimensionless quantity which is proposed for practical usage. Additionally, a simplified stress adaptation scheme is presented, which automatically adapts the prescribed stresses during the iterative form finding procedure, if a physically incompatible stress state is detected. This is especially important, as most of the form finding tasks in reality (e.g. prescribed constant anisotropic) show a slight incompatibility in their original problem formulation, which necessitates an automatic modification of the input parameters. Success is demonstrated by typical, challenging test cases. Further reference to practically relevant implementations of the proposed techniques is made.
A Trial for Seismic Fragility Evaluation of a Large Lattice Dome Supported by Buckling Restrained Braces
Authors: Kato Shiro , Nakazawa Shoji
Published: August 2010

A trial to evaluate the seismic fragility of a large dome supported by buckling restrained braces is performed and discussed in comparison with a dome supported by ordinary braces of tension-active capability. In order to evaluate the fragility depending on an adopted bracing system, the damage burdened to the dome structure due to earthquakes is calculated and interpreted as total fragility in terms of assumed seismic intensity varying from small to large earthquakes. The procedure for calculating the total fragility utilizes a simple event tree modelling, where the total fragility is counted considering the damage intensity to structural members, non-structural walls and ceilings. Based on a simple calculation, an example is illustrated to see how the buckling restrained braces are effective or not effective as an anti-seismic reinforcement method.
An Approximate Calculation Method for Air Inflated Cushion Structures for Design Purposes
Authors: Borgart Andrew
Published: August 2010

Air inflated cushions are being used more and more as light roofs for large span structures, such as the Eden Project in Cornwall, UK (fig. 1). Most of the air inflated cushions are made of FTFE foil. Because air inflated cushions are form active structures they are subjected to geometric non-linear behaviour. This is usually dealt with by calculating these types of structures with form finding and finite element programmes with special membrane elements. For design purposes these calculations can be cumbersome, and do not necessarily provide the designer the required insight to make effective early design decisions. For this reason researchers have tried to derive simpler analysis methods without disregarding its geometric non-linear nature (Wagner [1]). The method presented in this paper is a further step in developing these.
On the Optimal Design of Glass Grid Shells with Planar Quadrilateral Elements
Authors: Sassone Mario , Pugnale Alberto
Published: August 2010

This paper presents an optimization procedure for the solution of the planarity problem, a requirement of grid shells with four or more sides faces that need of having four adjacent nodes laying on a plane in order to use plane glass slabs as cladding elements. It can be satisfied by applying specific geometric rules in the grid generation phase but, when the architectural shape is already defined at the conceptual stage, an optimization procedure can yield to suitable configurations. A Relaxation method based on nodal planarity errors and an evolutionary population based Genetic Algorithm have been applied to set of benchmarks, in order to tune parameters and to obtain general information about the solution. the problem and their efficiency compared. The Relaxation method in general shows better efficiency in reaching optimal solutions, as an effect of the regularity of the target function. The Genetic Algorithm, on the other hand, performs a wider exploration of feasible solutions, generating unexpected sub-optimal configurations.
Flight Leader Concept for Wind Farm Load Counting: Offshore Evaluation
Authors: Obdam T.S. , Rademakers L.W.M.M. , Braam H.
Published: August 2010

ECN has developed a demo version of the Flight Leader model, which is based on a concept with which the accumulated mechanical loading of all turbines in an offshore wind farm can be estimated at acceptable costs. This information can be used to optimise and lower the cost of Operation & Maintenance (O&M), for example by prioritising inspections and replacements. In this paper the background and general concept of the Flight Leader model are presented. A full Flight Leader analysis has been performed using data from the Dutch offshore wind farm OWEZ. In this paper the approach and results of the analyses are discussed.
Italy's Wind Atlas: Offshore Resource Assessment through On-The-Spot Measurements
Authors: Casale C. , Lembo E. , Serri L. , Viani S.
Published: August 2010

The Wind Atlas of Italy, first developed in 2002, was refined by ERSE (former CESI RICERCA S.p.A.) in 2006, when it was also enlarged to offshore areas up to 40 km from the coastline. It displays maps of annual average wind speed (m/s) and specific energy production (MWh/MW) up to 100 m above ground or sea. This Atlas is published in an interactive version (named ATLAEOLICO). The Italian Wind Atlas is based on maps calculated using the WINDS model developed by the Department of Physics of the University of Genoa and has then been fine-tuned by comparison with measuring data from over 400 stations scattered all over Italy. Concerning offshore areas, the calibration of maps resulted more difficult because of the lack of direct measurements. The resulting uncertainty of wind maps over offshore areas has been estimated from a minimum of 2 m/s to a maximum of more than 3 m/s, which results in an uncertainty of no less than 1000 MWh/MW in specific energy production, too high for reliable evaluation of energy production.

To reduce this uncertainty, a new wind measuring station has recently been installed at Pianosa, a small uninhabited and flattish island located in the Adriatic Sea off the Gargano promontory, one of the offshore areas with higher discordance of wind speed values among the various maps published so far. This island could also be taken as representative of the transition from the southern zone with better resources to the less promising northern part of the Adriatic Sea.

This paper presents the results of the first eight months of measurements at this station. These results have been analyzed by commercial codes for wind resource assessment and then compared with available information on wind resources in the same area, mostly measurements from satellite and coastal stations, and other published wind atlases.
Feasibility of an Offshore Wind Farm in the Gulf of Gela: Marine and Structural Issues
Authors: Foti Enrico , Musumeci Rosaria Ester , Leanza Salvatore , Cavallaro Luca
Published: August 2010

Some of the marine and structural issues related to the installation of an offshore wind farm three miles away from the shoreline of Gela (Italy) are discussed. In particular, the characterization of the maritime climate has been carried out by considering the winds, the waves, the mean water level variations and the current regime. The results of such an analysis have been used in order to determine the environmental loads on the foundation structure. A gravity based structural type has been proposed as foundation of the wind turbines and the design of a foundation prototype has been carried out by trying to implement the most updated international standards to the Sicilian case. An original automatic optimization procedure has been developed in order to determine the dimensions of the design foundation, which satisfied the prescribed static verifications and provided the lowest costs. The scour process at the basis of the foundation and the wave run-up on the structure have been also taken into account. Finally, problems related to the laying and the maintenance of electrical connection cables are also discussed.
Structural Design and Analysis of Offshore Wind Turbines from a System Point of View
Authors: Petrini Francesco , Manenti Sauro , Gkoumas Konstantinos , Bontempi Franco
Published: August 2010

Offshore wind turbines are relatively complex structural and mechanical systems located in a highly demanding environment. In this study, the fundamental aspects and major issues related to the design of such structures are inquired. The system approach is proposed to carry out the design of the structural parts: in accordance with this philosophy, a decomposition of the system (environment, structure, actions/loads) and of the structural performance is carried out, in order to organize the qualitative and quantitative assessment in various sub-problems. These can be faced by sub-models of different complexity both for the structural behavior and for the load models. Numerical models are developed to assess the safety performance under aerodynamic and hydrodynamic actions. In the structural analyses, three types of turbine support structures have been considered and compared: a monopile, a tripod and a jacket.
The Potential of Integrating Wind Power with Offshore Oil and Gas Platforms
Authors: He Wei , Jacobsen Gunnar , Anderson Tiit , Olsen Freydar , Hanson Tor D. , Korpås Magnus , Toftevaag Trond , Eek Jarle , Uhlen Kjetil , Johansson Emil
Published: August 2010

Offshore wind technology has developed rapidly and an offshore wind farm has the potential to power nearby offshore platforms in the future. This paper presents a case study of integrating a 20 MW wind farm which addressed the theoretical challenges of integrating large wind turbines into a stand-alone oil and gas platform grid. Firstly, the operational benefits of the 20 MW wind power integration were quantitatively assessed with regard to the fuel gas consumption and CO2/NOx emissions reduction. Secondly, the electrical grid stability after integration of the 20 MW wind power was tested by nine dynamic simulations that included: motor starts, loss of one gas turbine, loss of all wind turbines and wind speed fluctuations. Thirdly, the maximum amount of the wind power available for integration was identified by simulating critical operational conditions and comparing these to the governing standards. Integration of an offshore wind farm to an oil and gas platform is theoretically possible, but has not been proven by this study and many other operational and economic factors should be included in future feasibility studies.
Effect of Rime Ice Accretion on Aerodynamic Characteristics of Wind Turbine Blade Profiles
Authors: Virk Muhammad S. , Homola Matthew C. , Nicklasson Per J.
Published: August 2010

A numerical study of rime ice accretion and resultant flow field characteristics of blade profiles for four different fixed speed, stall controlled wind turbines was performed. Analyses were carried out at Reynolds numbers ranging from of 2.5 × 106 to 5.5 × 106, corresponding to the operational wind speeds and angles of attack ranging from −10 degree to + 20 degree. Numerical analyses showed that an increase in blade profile size reduces the dry rime ice accretion at leading edge, both in terms of local mass and ice thickness. A significant change in the flow behaviour and aerodynamic characteristics is observed, when a comparison is made between plain and iced blade profiles. Results showed an increase in both lift and drag coefficients of wind turbine blade profiles with the leading edge ice.
Generalized Gain Scheduling for Deloaded Wind Turbine Operation
Authors: Venne Philippe , Guillaud X. , Teodorescu R. , Mahseredjian J.
Published: August 2010

The ability to produce less power than what is available from a wind source, a condition known as deloaded operation, is needed for a wind turbine to reproduce synchronous machine behavior in terms of inertial response and frequency droop regulation. Deloaded operation requires the ability to regulate both power production and rotor speed under any wind speed conditions. In this paper, a novel controller for deloaded wind turbine operation is presented. This controller is made possible by a Cp table inversion procedure allowing generalized gain scheduling for linearization of the pitch response. After introducing the wind turbine models, a review of classical turbine control principles and the proposed deloaded wind turbine control architecture is presented. A discussion of wind turbine non linearity and linearization principles follows. Simulation results are shown for stability, immunity to icing and performance. The advantages of generalized gain scheduling over classical gain scheduling are demonstrated by simulation results.
A Community Small-Scale Wind Generation Project in Peru
Authors: Ferrer-Martí Laia , Garwood Anna , Chiroque José , Escobar Rafael , Coello Javier , Castro Miguel
Published: August 2010

Electrification systems based on renewable energy have proven to be suitable for providing decentralized electricity to isolated communities. Electricity generated through wind power is one of the technical options available, although infrequently used to date. This article aims to describe the main aspects of technical design, implementation and management of the first small-scale community wind generation project for rural electrification in Peru. This project took place in the community of El Alumbre, in the region of Cajamarca, which is a mountainous area characterized by low to medium wind speeds. This project, implemented by Soluciones Prácticas – Practical Action (Peru), brought electric power to the 33 households (a total of 150 inhabitants) as well as the school and health center of the community.
Critique of the Book ‘The Wind Farm Scam — An Ecologist's Evaluation’, (2009), John Etherington, Stacey International, London
Authors: Twidell John
Published: August 2010

The book entitled ‘The Wind Farm Scam’ by John Etherington is being championed as a definitive text by anti-wind groups. This critique considers the content chapter by chapter with a serious analysis. The conclusion is that whilst some of the content is standard knowledge and therefore uncontested, much of the rest stems from an emotional predisposition against the visual impact of wind turbines that leads to prejudice and factual error. The amount of electricity from central generation that is abated by wind power is a key issue, which leads, in an illogical manner, to doubt about climate change. Encouraged by his publisher to state what generation he prefers, Etherington opts for nuclear power.
Active Noise Control in a Semi-Closed Aircraft Cabin
Authors: Kochan K. , Kletschkowski T. , Sachau D. , Breitbach H.
Published: August 2010

An active noise control system is developed for the loadmaster area of a propeller driven transport aircraft. The loadmaster area is a small semi-enclosed volume connected to the large cargo hold. This coupling of a small room with a large room yields to new questions when an active noise control system is designed: Which effects does the coupling have on the noise field inside the small loadmaster area? Which influence do these effects have on the active noise control system? How complex is the uncertainty induced by the coupling to the large cargo? The analysis of this coupling was done in two ways. The first one, an energy based method, is used to analyze the acoustical energy flow between the loadmaster area and the cargo hold. The second one, a substructure technique, is used to study the influence on the eigenfrequencies and eigenmodes of such a coupled system. Afterwards, the theoretic results were confirmed with an experimental forced vibration analysis. The most important result is that the shape of the noise field inside the loadmaster area is less sensitive in spite of the large cargo hold. Moreover, an active noise controller was developed to handle the controller tasks. First experimental control results are given in the last section. These results have shown successful noise reduction up to 23 dB without any controller optimization.
Smart Detection of Damage in a Cracked Cantilever Beam Using Artificial Intelligence
Authors: Sutar Mihir Kumar , Parhi D.R.K.
Published: August 2010

Increasing attention is being given to the detection of damage in structures. For this purpose different newer techniques are being used. In this paper a defect in a cantilever beam in the form of a transverse crack, is investigated using smart techniques such as Fuzzy Logic Controller. The input parameters to the fuzzy controller are relative divergence of first three natural frequencies, and the output parameters of the fuzzy controller are relative crack depth and relative crack location in dimensionless forms. For deriving the fuzzy rules for the controller, theoretical expressions have been developed considering three parameters such as; natural frequencies, crack depths and crack locations. Strain energy release rate has been used for calculating the local stiffnesses of the beam. The local stiffnesses of the beam are dependent on the crack depth. Different boundary conditions are outlined which take into account the crack location. Several fuzzy rules are derived and the Fuzzy controller has been designed accordingly. The experimental setup has been developed for verifying the robustness of the developed fuzzy controller. The developed fuzzy controller can predict the location and depth of the crack in close proximity to actual results.
A New Semantic Differential for Measuring the Perceived Quality of Aircraft Sounds
Authors: Schütte Martin , Müller Uwe , Lavandier Catherine , Griefahn Barbara
Published: August 2010

A new semantic differential (SD) was developed in order to measure the quality of aircraft sounds. The SD consists of 10 items which have relation to the emitted noise of different engine components and the airframe. The items refer to technical components of an engine. The reliability of an evaluation of one sound falls below the minimum value of 0.70 if only one judge is involved. For most of the items average scores based on sample sizes up to 30 judges will satisfy the requirements concerning reliability. The item “safe” should not be considered when evaluating arrival and departure sounds because a reliable measurement presupposes a considerable, greater sample size. For the same reason the item “powerful” should not be considered when arrival sounds need to be evaluated and the item “booming” should be disregarded when departure sounds need to be rated.
Condition Monitoring of Gears and Advanced Signal Processing Techniques towards More Effective Diagnostic Schemes
Authors: Loutas T.H. , Sotiriades G. , Kostopoulos V.
Published: August 2010

A diagnostic methodology of artificial defects in a single stage gearbox operating under various load levels and different defect states is proposed in the present work based on vibration recordings as well as advanced signal analysis techniques. Two different wavelet-based signal processing methodologies, using the discrete as well as the continuous wavelet transform, were utilised for the analysis of the recorded vibration signals and useful diagnostic information were extracted out of them. Both wavelet analysis techniques provided the ability of distinguishing between the healthy and the artificially defected gears. In this way, the health monitoring potential of vibration monitoring in the case of rotating machinery and gearboxes obtains a new dynamic under the prism of sophisticated time-frequency signal processing schemes, rather than conventional FFT-based approaches.
Biodiesel: Vehicle Fuel from Vegetable Oil
Authors: Button Scott
Published: August 2010

Biodiesel is an alternative fuel produced by the transesterification of triglycerides from natural oils with an alcohol. This review discusses the basic requirements for diesel fuels and how biodiesel meets these requirements. This information is correlated to the chemistry of biodiesel production including reactants, products, and contaminants and the techno-economic tradeoffs between process variables. Finally, this review examines the ecological significance of biodiesel and how ecological, economic, and ideological considerations will affect the future of biodiesel production in the United States and Europe.
Processing of Triglycerides to Diesel Range Hydrocarbon Fuels: Easily Practicable Small Scale Approach
Authors: Olusola James O. , Adediran Mesubi M. , Oluseyi Ajanaku K. , Ajao Usman L.
Published: August 2010

Lipid fraction of biomass has been identified as carbon neutral substitution to fuels from fossil sources in the transportation sector. Although, the diesel engine, invented by Rudolph Diesel over a century ago first ran on peanut oil, the current combustion engines are designed to run on hydrocarbon fuels derived from petroleum. Therefore, a substitute for diesel fuel from renewable source will need to have identical or closely similar properties. The most popular of the existing technology for processing vegetable or animal oils is based on the conversion of the triglycerides constituents to fatty acids methyl esters (FAME). FAME technology does not produce diesel fuel with identical properties as petro-diesel. Other alternative processing routes are dilution of the vegetable oils, emulsification, pyrolysis and hydrotreating. These routes are discussed in this paper. Appropriate technologies for small scale production of diesel range hydrocarbon fuel from vegetable oil without the need for co-reactants such methanol or hydrogen as part of the feedstock is emphased. Also alternative catalyst systems in place of the expensive precious metal supported catalysts are suggested.
Performance and Emission Characteristics of Diesel Engine with Methyl Ester Jatropha Oil and its Blends
Authors: Rao Y. V. Hanumantha , Voleti Ram Sudheer , Hariharan V.S. , Reddy P. Nageswara , Raju A.V. Sita Rama
Published: August 2010

Biomass derived vegetable oils are quite promising alternative fuels for agricultural diesel engines. Use of vegetable oils in diesel engines leads to slightly inferior performance and higher smoke emissions due to their high viscosity. The performance of vegetable oils can be improved by modifying them through the Transesterification process. In this present work, the performance of single cylinder water-cooled diesel engine using methyl-ester of Jatropha oil as the fuel was evaluated for its performance and exhaust emissions. The fuel properties of biodiesel such as kinematic viscosity, calorific value, flash point, carbon residue and specific gravity were found. Results indicated that B25 have closer performance to diesel and B100 had lower brake thermal efficiency mainly due to its high viscosity compared to diesel. The brake thermal efficiency for biodiesel and its blends was found to be slightly higher than that of diesel fuel at tested load conditions and there was no difference between the biodiesel and its blended fuels efficiencies. For Jatropha biodiesel and its blended fuels, the exhaust gas temperature increased with increase in power and amount of biodiesel. However, its diesel blends showed reasonable efficiencies, lower smoke, CO2, CO and HC.
Application of High Temperature Heat Pipe for Renewable Energy Development
Authors: Xu Hui , Zhang Hong , Wang Zhongxian , Bai Tong , Ding Li , Zhuang Jun
Published: August 2010

This article suggests the use of high temperature heat pipes application for development to provide renewable energy. A high temperature heat pipe is a device which exhibits an extremely high effective thermal conductivity at temperatures of about 450 to 1000 °C by means of two-phase fluid flow with capillary circulation. It has the features of high thermal conductivity, good isothermal performance, automatic adjustment of heat flux, reversible heat flow direction, thermal diode and thermal switch characteristics, a structure allowing flexible arrangement and high reliability. This paper considers using heat pipes as receivers for a high temperature solar thermal power system, and describes several heat pipe biomass gasifiers for power generation biomass gasification systems. The special operating conditions of these renewable energy systems are analyzed. The structure and principles of these heat transfer devices by use of high temperature heat pipes are expounded, and potential for their development and application prospect are assessed.