Windmill Type Research Articles

What do dendrochronology and other timber-dating methods tell us about the history of english post mills?

Post mills are a distinctive type of windmill that has had a long history in England. Today only 47 post mills still survive in England. Evidence from 15 of these where their timbers have been subjected to dendrochronological investigations combined with other sources of evidence helps build a picture of the history of each of these mills. Most mills contain timbers from different historical rebuilding phases, but with the main posts often being the oldest component. Bourn Windmill was the earliest of these (the tree from which the main post was made being felled sometime after 1515) but Nutley and Pitstone mills retain almost equally ancient main posts. Scientific timber-dating methods can help corroborate the historical narrative derived from other evidence, such as documentary sources or inscriptions; however, they can also help raise completely new questions, illuminating stages in the history of a structure that were previously unknown or unsuspected.

Technological Heritage of Persian Windmills

ABSTRACT Persian windmills are usually referred to as the earliest windmills in the history of technology. These windmills, well-known for their vertical axle design, are distributed over the Irano-Afghan borderland. This multidisciplinary investigation on windmills and their millstones from eastern Iran shows that there are various types of Persian windmills, despite their similar features. Four clusters of windmills exist in different regions of eastern Iran, distinctive in their construction, mechanical system, and types of their millstones. Three groups from the semi-highland of eastern Iran used natural rocks for their millstone, whereas the fourth group in the lowland applied artificial millstones made by a complex pyrotechnolgy. Functional windmills have been present only in the semi-highland but have not been reported from the lowland since the beginning of the last century. This article sheds light on technical details and the history of this earliest known type of windmill and helps their restoration process by providing an appropriate typology.

Switchable dual-band and ultra-wideband terahertz wave absorber

In this paper, we introduced a switchable dual-band and ultra-wideband terahertz wave absorber based on photoconductive silicon combining with vanadium dioxide (VO2). In the terahertz absorber, photoconductive silicon cross array, silicon dioxide layer, vanadium dioxide windmill type array, silicon dioxide dielectric layer, and gold ground plane are placed from the top layer to bottom layer in sequence. When VO2 is in a metallic state and the conductivity of photoconductive silicon is 2.5×10−4 S/m, the designed structure represents an ultra-wideband absorber with an absorption larger than 90% in the range of 3.14∼7.80 THz. As VO2 is in an insulation state and the conductivity of photoconductive silicon becomes 8.0×104 S/m, the designed device acts as two absorption bands, with a terahertz wave absorber with absorption more than 98% at 1.78∼2.90 THz and 7.35∼8.45 THz. The results show that the absorption band (dual-band or ultra-wideband) and absorption intensity (from 2% to 99%) can be switched by changing the phase transition of the VO2 and the conductivity of photoconductive silicon. Furthermore, the proposed device exhibits polarization insensitive and wide incident angles (lager than 70°) for TE- and TM- polarizations incidence.

Study of comparison of tail wind turbines in wind power plants

The windmill tail that is widely used is a single tail that has a performance of a large zero offset. This study is to get a windmill tail pattern with a fast response and good direction stability. The aim of this study is to obtain a windmill tail pattern with the most stable direction stability under load conditions and changing wind direction by comparing the stability of several alternative windmill tail patterns. The process of data collection is done by comparing the performance of 3 types of windmills: single tail, semi-differential tail, and differential tail. The variables are speed of wind direction, speed of change of wind direction, differential angle of zero offset error, speed of change of direction, and torque produced. The material obtained from the test results was transcribed and analysed. The results of the analysis are used to design windmill tail prototypes. From the analysis results show that the swing torque at the differential windmill tail is proportional to the sinusoidal swing angle, the differential angle gives the effect of the torque scale in a cosine manner. Whereas on a single pinwheel produces torque proportional to the sine squared with respect to the swing angle. The differential tail has performance with better speed and stability, but produces vertical vibrations so it is preferable to use a semi-differential pinwheel with a differential angular size tuned in the system.

Distribution and types of windmills in Pomerania across the 19th century in the light of cartographic sources

Abstract The aim of this text is to evaluate the distribution of windmills in Pomerania, an area which stretches from Gdańsk to Toruń, over the period of the nineteenth century. The basic research method was to analyse various maps from both the early nineteenth century and the late nineteenth century. The results made it possible to state that the total number windmills increased by a factor of three, and that this referred mainly to cereal mills. The number of vertical windmills with rotating caps increased at the beginning of the nineteenth century, but the number of drainage windmills remained unchanged. The very high demand for wind energy was a result of significant economic development within the Prussian partition in the second half of the nineteenth century. Cartographic sources allowed this phenomenon to be verified in the most complete way.

Conceptual Design of Innovative Eco-Friendly Windmill

A wind turbine performs the function of converting the energy (kinetic) derived from the wind into another form of energy (mechanical) which is employed for the purpose of driving the generator which in turn generates electricity from this mechanical energy. The most common types of windmills employed in practice include horizontal and vertical axis wind mill. These windmills are fabricated in different structures for producing electricity. The main objective of this paper is to design an innovative eco friendly windmill to overcome the various difficulties existing in conventional windmills. In conventional windmills, the propeller rotation depends on the velocity of wind flow in the environment. But in this paper, we have fabricated an innovative eco friendly windmill in which, the propeller rotation is increased four times for the wind velocity in the surroundings.

Phonation Quotient in Women: A Measure of Vocal Efficiency Using Three Aerodynamic Instruments

The purpose of this study was to examine measures of vital capacity and phonation quotient across three age groups in women using three different aerodynamic instruments representing low-tech and high-tech options. This study has a prospective, repeated measures design. Fifteen women in each age group of 25-39 years, 40-59 years, and 60-79 years were assessed using maximum phonation time and vital capacity obtained from three aerodynamic instruments: a handheld analog windmill type spirometer, a handheld digital spirometer, and the Phonatory Aerodynamic System (PAS), Model 6600. Phonation quotient was calculated using vital capacity from each instrument. Analyses of variance were performed to test for main effects of the instruments and age on vital capacity and derived phonation quotient. Pearson product moment correlation was performed to assess measurement reliability (parallel forms) between the instruments. Regression equations, scatterplots, and coefficients of determination were also calculated. Statistically significant differences were found in vital capacity measures for the digital spirometer compared with the windmill-type spirometer and PAS across age groups. Strong positive correlations were present between all three instruments for both vital capacity and derived phonation quotient measurements. Measurement precision for the digital spirometer was lower than the windmill spirometer compared with the PAS. However, all three instruments had strong measurement reliability. Additionally, age did not have an effect on the measurement across instruments. These results are consistent with previous literature reporting data from male speakers and support the use of low-tech options for measurement of basic aerodynamic variables associated with voice production.

Polarization and incidence insensitive dielectric electromagnetically induced transparency metamaterial

In this manuscript, we demonstrate numerically classical analogy of electromagnetically induced transparency (EIT) with a windmill type metamaterial consisting of two dumbbell dielectric resonator. With proper external excitation, dielectric resonators serve as EIT bright and dark elements via electric and magnetic Mie resonances, respectively. Rigorous numerical analyses reveal that dielectric metamaterial exhibits sharp transparency peak characterized by large group index due to the destructive interference between EIT bright and dark resonators. Furthermore, such EIT transmission behavior keeps stable property with respect to polarization and incidence angles.

ZnO Hierarchical Nanostructures: Simple Solvothermal Synthesis and Growth Mechanism

Hierarchical nano/micro structures of ZnO have been fabricated by solvothermal approach on sol-gel derived ZnO thin films. Paintbrush like nano/micro rod assembly, double-sided brush and windmill type architectures of ZnO are obtained when the ZnO thin film coated substrates were treated solvothermally in water at pH 10. Aligned nanorods are obtained at pH approximately 13.5 in water. In ethylenediamine-water solvent divergent micro/nanorod assemblies such as hemispherical dandelion, rice plant type bush of ZnO are obtained. Increase in the percentage of ethyelendiamine resulted in the formation of smaller assemblies of relatively thin nanorods. Initial slow reaction caused by the slow increase of the temperature inside the reaction medium and the different growth kinetics of the ZnO crystals are supposed to be the reason behind the architectural assemblies of the ZnO crystals.

A rational approach for regulating windturbine noise

Windturbines have evolved from the cosy, wooden Dutch windmill type to large industrial generators of sustainable energy. Their noise production luckily did not evolve in step, but in some cases they can be a perhaps unsustainable nuisance for population living nearby. Presently the local and national authorities are trying to get a hold on the problem, often still using methods from the wooden machine age. The paper describes a modern approach for dealing with windturbine noise, using harmonized methods and recently acquired insights in the reaction of people to this particular noise. Tentative dose‐effect relations in terms of Lden and Lnight enable comparisons with noise from transport.

Computer-aided design and engineering: A study of windmills in la Mancha (Spain)

This article presents a detailed study, of the Manchegan windmill. This type of windmill is a central symbol in the story of Don Quijote de la Mancha, by Cervantes, which this year celebrates its 4th centenary, and to which this article pays homage. There exist no publications dealing with the technical aspects of these windmills. Studies have been carried out on windmills in the south of Spain, but no comparison has been made between the two types of windmill. This paper studies the technological conditions of the original Manchegan windmills. We carry out a wind evaluation of the region, calculate the power and momentum of the windmills and discuss the results obtained with a comparison with the type of Southern Spanish windmill.

Tetrathiapentalene-type donors containing (thio)pyran-4-ylidene as a promising π-electron framework for multi-dimensional molecular conductors

The conducting materials based on 2-(l,3-dithiol-2-ylidene)-5-(pyran-4-ylidene)-1,3,4,6-tetrathiapentalene (PDT-TTP) and its thiopyran and/or selenium analogues have been developed. The ethylenedithio derivative (ET-PDT) affords 4:1 salt with PF 6 - anion (ET-PDT) 4 PF 6 (cn) (cn = l-chloronaphthalene). It has the so-called λ-type array of the donors with quasi one-dimensional electronic structure due to strongly tetramerized stack. On the other hand, (TM-TPDS) 2 AsF 6 adopt the windmill type array of the donors. In this salt, relatively large side-to-edge interactions stabilize their electronic structure, while effective side-by-side interaction is inhibited by methythio groups projected along the molecular short axis. In contrast, edge-to-edge interactions are dominant in (SM-PDT)PF 6 (PhCl) x through selenium-selenium contacts along the molecular long axis. (ET-PDT) 4 PF 6 (cn) shows metallic conductivity down to 1.5 K, while (TM-TPDS) 2 AsF 6 is an organic metal exhibiting MI transition at 100 K. On the other hand, (SM-PDT)PF 6 (PhCl) g is a semiconductor with relatively high conduuctivity of σ rt = 4.8 S cm -1 in spite of 1:1 composition.

Screw-Type Windmills and Their Particular Features

A new type of windmill based on a screw-type wind receiver has appeared recently. In the present article, the principles of operation of screw-type windmills and their geometric characteristics are discussed. Attention is given to the design and technology of manufacture of a screw-type rotor; possible arrangements of wind-power plants with a screw-type rotor are shown. The procedure of calculation of the power characteristics is substantiated. Screw-type windmills are noiseless and environmentally safe; they show promise as the least expensive ones.

Composite ultrasonic motors using a piezoelectric disc and an elastic body of “windmill” type

This paper deals with a new piezoelectric ultrasonic motor operated by single-phase AC. The ultrasonic motor of windmill type using a piezoelectric ceramic and a metal elastic body was fabricated. To prepare the piezoelectric ceramics vibrator. 0.05PMN-0.95PZT composition was mixed with 0.7wt% MnO2. Dielectric loss, the electromechanical coupling factor of radial mode and mechanical quality factor were 0.2%, 62.8% and 820, respectively. The slotted metal elastic bodies made from brass sheet were machined at various thickness of 0.15, 0.20,0.25,0.30mm, and slots of the elastic body were 2.3.4.6, respectively. No-load revolution speed increases with increasing applied voltage, and it increases with decreasing the thickness of the elastic body. The revolution speed of the ultrasonic motor is 510rpm under an applied voltage of 100 Vmax

An experimental study of the windmill of solar cell buckets

In order to demonstrate a complementary relationship between solar energy and wind energy, the authors proposed the WISH(Wind and Solar Hybrid) type windmill. The flexible amorphous photovoltaic modules are attached to the buckets of Savonius type windmill. After eight months operation of the WISH type windmill in the field, we confirmed that there exists a complementary relationship between solar energy and wind energy. We also found that the power generation of this type of windmill was nearly twice as large as those without photovoltaic modules.

Design and field testing Savonius wind pump in East Africa

SYNOPSIS This paper describes improvements in the wind-scoop geometry and efficiency of a double-stack Savonius rotor, developed through a series of wind tunnel and field tests in East Africa. On an aerodynamic performance basis, the Savonius rotor cannot generally compete with other types of wind turbines. This is entirely due to its mode of operation. Unlike its counter-parts that operate by rotating around a horizontal axis, it rotates around a vertical axis. This has the unfortunate effect of lowering its efficiency, but it has several compensating factors. Its main advantages are that it has better starting torque performance with operating characteristics independent of the wind direction. In addition, it is simple in structure and the fabrication technology required is less sophisticated when compared to similar types of windmills. This makes it a suitable system for small scale applications in wind energy conversion; especially in remote rural regions in developing countries.

Wind tunnel tests on a 3m diameter Musgrove windmill

SYNOPSIS A 3m diameter model of a two bladed Musgrove vertical axis windmill has been tested in the British Aerospace wind tunnel at Filton. Tunnel constraints were kept to a minimum by using a low flow blockage and appropriate corrections were applied to the measurements. The results of these tests demonstrate the good performance of this type of windmill. Comparison of the measured performance with predictions from a simple mathematical model show excellent agreement. Maximum loads measured on the windmill are not well predicted by the mathematical model. In order to reconcile measurement and prediction large induced crossflows must be postulated at some blade rotational positions.

Cretan windmills

A resurgence of interest in this type of windmill has occurred recently because of its design simplicity and low cost. With it a relatively high rate of energy extraction may be achieved from low-speed winds.

Étude Synoptique des Différents Types D'éoliennes

(1957). A synoptic study of the different types of windmills. La Houille Blanche: Vol. 43, No. 2, pp. 189-212.

Airscrews at Supersonic Forward Speeds

SummaryThe flow past an airscrew rotating with uniform angular velocity in a uniform supersonic stream is considered from the point of view of axes fixed in the airscrew, the motion relative to these axes being steady. A linearised equation and boundary conditions are found for the potential of the disturbance flow caused by airscrews which produce only small perturbations in the main stream. This equation is solved by expanding the potential in powers of the ratio, χ, of the tip speed of the airscrew to the speed of sound in the undisturbed stream. Equations and boundary conditions are found for the coefficients of each term of the series and it is seen that the term independent of χ satisfies the ordinary linearised potential equation for fixed axes. By subtracting suitable special integrals, the more complicated equations for the coefficients of the various powers of χ can be reduced to this ordinary potential equation. Hadamard's methods have been applied by Puckett, Evvard and, finally, Ward to the problem of finding the flow past a thin wing fixed in a supersonic stream and their methods are applied to find the terms of the series in our case. The first two terms are found explicitly for a particular type of windmill. Approximate expressions are then developed for the torque and the drag on such a windmill and the results applied in special cases. The best working conditions for windmills of this type are found by considering the effect on efficiency and power of varying the shape and the speed of rotation, within the limits imposed by the strength of the material of the airscrew.