Typical Fan Research Articles

Landscape response to the deposition of airfall pyroclastics from large explosive eruptions: An example from the campanian area (Southern Italy)

We present in this work data about a peculiar type of alluvial fans formed exclusively by volcaniclastic material from large explosive eruptions. Each alluvial fan results formed by the superimposition of several sedimentary bodies, each of them formed by quite homogeneous volcaniclastic material. Lithological analyses allow us to correlate each sedimentary body with the emplacement of pyroclastics from Phlegrean Fields or Somma-Vesuvius. The development of these alluvial fans is controlled by three main factors: area of dispersion of pyroclastics, morphological features of the supplying basin (i.e. mean slopes and area) and climate. Finally, we present an assessment of the minimum time needed for the complete remobilization of pyroclastics of Pomici di Base and Greenish eruptions.

A conceptual approach to classifying sports fans

Develops a classification or typology of the sports fan. Specifically, contends that five different types of sports fans exist: temporary, local, devoted, fanatical, and dysfunctional. The need exists to identify the different types of fans due to the inadequacies of past theories to explain the totality of fan behavior. The usefulness of the typology is demonstrated by offering specific segmentation strategies for each classification. Finally, directions for future research are presented.

A comparison of fluvial megafans in the Cordilleran (Upper Cretaceous) and modern Himalayan foreland basin systems

The Campanian–Maastrichtian Hams Fork Conglomerate Member of the Evanston Formation in northeastern Utah and southwestern Wyoming consists of a widespread (>10 000 km 2 ) boulder to pebble, quartzitic conglomerate that was deposited by east-southeastward–flowing, gravelly braided rivers on top of the frontal part of the Sevier fold-thrust belt and in the adjacent foredeep of the Cordilleran foreland basin. In northeastern Utah the conglomerate was deposited in a lobate fan-shaped body, up to 122 m thick, that trends southeastward away from its principal source terrane in the southern end of the Willard thrust sheet. The Willard sheet contains thick Proterozoic quartzite units that produced highly durable clasts capable of surviving long-distance fluvial transport. Although the main source of sediment for the Hams Fork Conglomerate was the Willard sheet, the active front of the thrust belt lay 40–50 km to the east along the Absaroka thrust system. Displacement along the Absaroka system uplifted and topographically rejuvenated the Willard sheet, and antecedent drainages carried detritus from hinterland source terranes into the proximal foreland basin. Although topographic ridges associated with fault-propagation anticlines along frontal thrusts locally influenced transport directions, they provided relatively little sediment to the Hams Fork Conglomerate. Lithofacies, paleocurrent, and isopach data indicate that the Hams Fork Conglomerate was deposited in fluvial megafans and stream-dominated alluvial fans, similar in scale and processes to megafans and alluvial fans in southern Nepal and northern India that are forming along the proximal side of the Himalayan foreland basin system. The Himalayan fluvial megafans have areas of 10 3 –10 4 km 2 , slopes of 0.05°–0.18°, and are deposited by large transverse rivers that are antecedent to frontal Himalayan structures and topography. The main fluvial channels on the upper parts of the megafans are anastomosed and braided at bankfull stage but commonly have braided thalwegs at low-flow stage. Downstream, these channels become predominantly braided and meandering and ultimately merge with the axial Ganges trunk river system. Stream-dominated alluvial fans in the Himalayan foreland basin system fringe the topographic front of the fold-thrust belt in the intermegafan areas. These fans have areas of ∼10 2 km 2 and slopes of ∼0.5°. The proximal parts of both types of fans are dominated by extremely coarse (boulder-cobble) bedload that is in transit mainly during the monsoon. The prevalence of fluvial megafans in the modern and Miocene Himalayan foreland and in the Upper Cretaceous–lower Tertiary stratigraphic record of the Cordilleran foreland suggests that these types of deposits may be the volumetrically largest gravel accumulations in nonmarine foreland basin systems.

Modelling alluvial fan morphology

A mathematical model which estimates the scale-independent sediment surface profile of alluvial fans has been developed. This model utilizes a diffusive sediment transport model and an unsteady, radial flow, conservation relationship. These equations are approximately solved assuming a quasi-steady-state closure with appropriate modelling assumptions for two end member fan types: (1) fans where most of the fan surface is depositionally active (denoted here as ‘homogeneous’) and (2) fans characterized by channelling and sediment sorting processes. The fundamental result for these two fan types is a dimensionless sediment profile relationship which approximates most fan surfaces. The model suggests that the overall dimensionless morphology of alluvial fans is governed more by fundamental diffusion principles in sediment deposition than by individual environmental or basin characteristics. Additionally, this work potentially can be extended to model temporal variation in fan development. Preliminary comparison with alluvial fan profiles is reasonable, indicating that this model provides useful qualitative and quantitative information relating to alluvial fan process and morphology. Copyright © 1999 John Wiley & Sons, Ltd.

Regional implications of structural and eustatic controls in the evolution of submarine fans: an example from the Miocene Adana Basin, southern Turkey

Deep-sea fan development is generally thought to be controlled by a combination of changes in sea level, the shape and size of the basin in which the fans are growing, and the nature of the source area. The Early Miocene evolution of the eastern Mediterranean involved significant accumulation of deep-water clastic sediment in which the importance of each of these controlling factors can be evaluated. The deep-water clastic system located in the Adana Basin has been studied in detail. Two contemporaneous, small, radial, sand-rich submarine fans (one in the west and one in the east) exhibiting different scales, fan types and styles of deposition have been recognized within the Cingöz turbidite sequence of the northern Adana Basin in southern Turkey. Sedimentological studies indicate that the fans were controlled externally by tectonics and relative eustatic sea-level fall during late Serravallian time, in combination with the nature of the source area to the north. The internal architectural stacking patterns and external geometry of the two fan systems were strongly affected by the interaction of local tectonics and turbidity current pathways, including a major topographic confinement to the southeast that forced a vertical aggradation of the eastern fan and an east–west elongation of the western fan. This paper describes a classic example of a well-exposed deep-water clastic system where (1) tectonically driven sea-floor topography, (2) syn-sedimentary tectonism and (3) eustatic rise in sea level, are the primary controls on its development.

Stage characteristics for the development of late Quaternary paleosols in the Yangtze Delta area

The late Quaternary paleosols in the Yangtze Delta area developed in the period of 25 000–12 000 aBP. Phytolith ratios (value A) of contents of fan, square and rectangle types indicating the warm and humid climate to those of bar, hat and point types indicating cold and dry climates decrease upwards overall on profiles of the paleosols, suggesting that the climates turned from warm and humid to cold and dry. So, the paleosols developed mainly during the regression before the last glacial maximum. Changes of value A indicate no trend of warming, suggesting that the transgression was rapid after the last glacial maximum. The development of the paleosols exhibited obvious stages, which were controlled remarkably by transgression and regression: I. Period of alternation of deposition and pedogenesis, which was from the occurrence of regresson before the last glacial maximum to the time when sea levels fell close to the lowest; II. Exposure period with continual pedogenesis, which was terminated when the paleosols were drown in the post-glacial transgression; III. Period of being drown and buried, the paleosols were buried by marine sediments, and reworked by early diagenesis.

ノート型パソコン用小形軸流送風機における漏れ磁束と騒音との関係

Fans are used to control the temperature rise of the central processing units of notebook PCs. They are generally located inside the body of the PC. The magnetic flux leakage sometimes affects the performance of other electric devices. It is said that, 3 dB noise difference is very significant when such a PC is used in a silent room at midnight. The main factor in the magnetic flux leakage and the noise is the performance of the fan. This paper deals with a method of reducing the magnetic flux leakage and the noise of the fan without changing the outer body design and the performance. The magnetic flux leakage and the noise characteristics of two types of fans are discussed. One is a resin impeller fan (resin motor), and the other is a metal (steel) impeller fan (metal motor).The main findings are as follows:(1) If the resin impeller is replaced by a metal one, the magnetic flux leakage of the metal motor is 49.5 % lower on the upper surface of case, and 50.8 % lower on the side than the magnetic flux leakage of the reisin motor.(2) According to the experimental data, the noise of the metal motor is from 4 to 8 dB lower than that of the resin motor.

Optimization of heat sink geometries for impingement air‐cooling of LSI packages

This paper describes the use of our previous study's prediction procedures for calculating thermal resistance and pressure drop. The procedures are used in the optimization of heat sink geometries for impingement air-cooling of LSI packages. Two types of heat sinks are considered: ones with longitudinal fins and ones with pin fins. We optimized the heat sink geometries by evaluating 16 parameters simultaneously. The parameters included fin thickness, spacing, and height. For the longitudinal fins, the optimal fin thicknesses were found to be between 0.12 and 0.15 mm, depending on which of the four types of fans were used. For pin fins, the optimal pin diameters were between 0.39 and 0.40 mm. Under constant pumping power, the optimal thermal resistance of the longitudinal fins was about 60% that of the pin fins. For both types of heat sinks, the optimal thermal resistance for four off-the-shelf fans was only slightly (maximum about 1%) higher than the theoretical optimum for the same pumping power. When manufacturing cost performance is considered, the most economical fin thickness and diameter are about 5 to 10 times higher than the optimal values calculated without respect for manufacturing costs. These values almost correspond to the actual limits of extrusion and press heat-sink manufacturing processes. © 1999 Scripta Technica, Heat Trans Asian Res, 28(2): 138–151, 1999

Optimization of heat sink geometries for impingement air-cooling of LSI packages

This paper describes the use of our previous study's prediction procedures for calculating thermal resistance and pressure drop. The procedures are used in the optimization of heat sink geometries for impingement air-cooling of LSI packages. Two types of heat sinks are considered: ones with longitudinal fins and ones with pin fins. We optimized the heat sink geometries by evaluating 16 parameters simultaneously. The parameters included fin thickness, spacing, and height. For the longitudinal fins, the optimal fin thicknesses were found to be between 0.12 and 0.15 mm, depending on which of the four types of fans were used. For pin fins, the optimal pin diameters were between 0.39 and 0.40 mm. Under constant pumping power, the optimal thermal resistance of the longitudinal fins was about 60% that of the pin fins. For both types of heat sinks, the optimal thermal resistance for four off-the-shelf fans was only slightly (maximum about 1%) higher than the theoretical optimum for the same pumping power. When manufacturing cost performance is considered, the most economical fin thickness and diameter are about 5 to 10 times higher than the optimal values calculated without respect for manufacturing costs. These values almost correspond to the actual limits of extrusion and press heat-sink manufacturing processes. © 1999 Scripta Technica, Heat Trans Asian Res, 28(2): 138–151, 1999

Submarine fans and related depositional systems ii: variability in reservoir architecture and wireline log character

The architecture and heterogeneity of deep-marine clastic reservoir systems can be assessed at three scales. At the macroscale, lateral and vertical variations in the stacking patterns of submarine fans or fan complexes fundamentally affects the shape and scale of a reservoir and its trapping geometry. At the mesoscale, the distribution and type of architectural elements, (e.g., channel-levees, lobes, sheet sands) within the fan system have a major impact upon reservoir compartmentalisation and the distribution, continuity and connectivity of sand/shale bodies. Finally, at the microscale, the vertical and horizontal arrangement of reservoir and non-reservoir facies and lithotypes defines flow units which fundamentally control fluid flow and production performance. Each type of submarine fan and related deep-marine clastic reservoir system (sand-rich fans, mixed sand–mud ramps etc.) exhibits a predictable arrangement of architectural elements which form the basic building blocks of the system. These features control reservoir architecture, seismic expression and the geometry of sandbodies and non-reservoir section. A suite of reservoir architectural models is proposed for different deep-marine clastic systems using unpublished and cited data from outcrop and subsurface studies. These conceptual models are idealised simplifications which provide a preliminary framework for understanding broad scale reservoir archsitecture and wireline-log character within contrasting types of fan and related systems. The models are of value in the exploration for turbidite reservoirs by highlighting the risk on reservoir presence and distribution from an appreciation of the architectural style. Within appraisal and production they provide a basic framework from which an objective reservoir description can be made. Use of such conceptual analogue models for reservoir description will not adequately reflect the reality and individuality of a specific reservoir. Their use in understanding detailed reservoir complexity should therefore be approached with caution.

Submarine-fan systems i: characterization and stratigraphic prediction

Submarine-fan and related deep-marine clastic systems such as submarine ramps and slope aprons are important hydrocarbon reservoirs in many parts of the world. The origin and character of these systems reflect a complex interplay between a range of autocyclic and allocyclic controls including sea-level fluctuations, basinal tectonics and the rate, type and nature of sediment supply. These controls are commonly interdependent. This paper reviews the characteristics which distinguish different submarine-fans and their subsurface prediction, then proposes a classification framework for fans which discriminates between different systems on the basis of their fundamental controls. The proposed classification is discussed in terms of its value as a predictive tool in hydrocarbon exploration, development and production. A modus operandi is developed which uses the classification for reservoir description and prediction and involves three stages of investigation: basin screening, fan delineation and fan characterization. Each stage demands the integration of a range of tools and techniques including sequence stratigraphy, seismic facies analysis, seismic redisplay and geophysical modeling. These stages of analysis are linked, in turn, with core and wireline log data to constrain the range of possible fan types within a basin-fill and assess the implications for reservoir seal and trap development. This structured approach to stratigraphic analysis is also valuable in constraining the range of reservoir architectural options in appraisal, development and production.

THE INFLUENCE OF UNEVEN BLADE SPACING ON THE SPL AND NOISE SPECTRA RADIATED FROM RADIAL FANS

The influence of irregular blade spacing of car alternator radial fans on the total sound pressure level (SPL) and the noise spectrum has been investigated. For this purpose, theSPLand spectra were computed theoretically and the values were compared to measured results for several types of fans with various blade spacing. As theoretical background, the theory describing discrete frequency sound radiated by axial fans in open space was adopted. This was done in order to model theSPLand the spectra of alternator radial fans, placed inside a casing. Furthermore, due to the low blade tip Mach number, blades were modelled as dipole point sources. It was found, in accordance with previous results from known literature, that alterations in blade spacing do not significantly alter the totalSPLnor the cooling capacity of the alternator radial fan. However, significant dispersion of the sound power over several harmonics was found with irregular fan blade spacing, thus allowing for a reduction of the siren effect. This phenomenon was predicted theoretically and confirmed experimentally.

Controls on modern fan morphology in Calabria, Southern Italy

Alluvial fans are widespread throughout Calabria, but only a minority display evidence of current activity. In order to understand if and to what extent fan types and their morphology are dependent on the physical environment, including characteristics and processes of the depositional site and drainage basin, we performed a series of discriminant analyses. These analyses used as classification factors the presence or absence of fill in the feeder channel, conditions of confinement by host terrain, the dominant depositional process (debris-flow or sheetflood); and morphometric attributes of fans and drainage basins as the discriminant function variables. In general, fan slope, area and width–length ratio, and, for basins, Melton's ruggedness number and source ratio, were the most useful variables for classification. Best results were obtained by discriminating the types of fan deposits and the presence versus absence of fill in the feeder channel, if the feeder source is singular. Fan morphology is controlled by constructional processes and is tightly linked to basin morphology. On the other hand, fan and basin morphology are also strongly dependent on the rock mechanical characteristics, with hard rocks imparting to the basin a high ruggedness and to fans a high gradient. Larger fans, however, are those where sheetflooding predominates. Results of discriminant analysis based on fan and basin variables are much more significant than those based on fan variables only. This means that the differences between characteristics of fan-and-basin systems are better defined than those between characteristics of fans only.

Wake Decay: Effect of Freestream Swirl

A study of the effects of freestream swirl on the decay characteristics of wakes shed from a rotating blade row is presented. The freestream swirl behind the rotor causes the wakes to skew tangentially, stretching the wakes as they are convected from the rotor to the stator. The effect of stretching on wake decay is illustrated using a simplified two-dimensional model. The model is described and the results are compared to 1) measurements from a two-dimensional cascade facility where no stretching or skewing of the wakes occurs, 2) solutions obtained using a three-dimensional, Reynolds-averaged Navier-Stokes solver, and 3) experimental wake measurements taken behind a low hub-to-tip ratio fan.For typical fan geometries with hub-to-tip ratios of approximately 0.5 and rotor-stator spacings of one to two rotor chord lengths, the wake can be stretched by over 50 percent. The stretching increases the mixing rate which leads to a reduction in the mean wake velocity deficit of approximately thirty percent and a widening of the wake of about fifteen percent. These effects account for much of the difference seen between cascade wake measurements and those taken behind rotating fan blade rows. It is therefore important to include such effects when using cascade data for prediction of fluid mechanic, acoustic, or structural phenomena associated with fan wakes. Finally, the study also suggests a potential for small (< 3 dB) reductions in wake-stator interaction noise through tailoring the fan loading distribution to produce particular span wise wake decay characteristics.Copyright © 1997 by ASME

EFFECT OF ROTOR ECCENTRICITY AND MAGNETIC CIRCUIT SATURATION ON ACOUSTIC NOISE AND VIBRATION OF SINGLE-PHASE INDUCTION MOTORS

ABSTRACT Existing theory for the analysis of the acoustic noise and vibration produced by single-phase induction motors is restricted to 2-pole machines (Yang, 1975). In this paper it is extended to cater for motors having any number of poles, and is then used to analyse the noise and vibration spectra of a typical 4-pole PSC motor and fan assembly. Both electromagnetically and aerodynamically generated noise and vibration are studied, with particular emphasis on the effects of rotor eccentricity, magnetic circuit saturation, and stator and rotor resonances.

Murder as Social Criticism

By Stephen F Soitos University of Massachusetts Press, 1996 Where do you read detective fiction? On airplanes? By the shore? In bed? If you are a typical fan of the genre, wherever or whenever you read a detective novel you enjoy that sense of delighted ease generated by a good vacation. The plot of detection just interesting enough to stimulate your little gray cells, while the surety of the novel's progression from confusion to solution as soothing as an afternoon spent dozing in a hammock while someone else prepares supper. But while this sensation of languor attested to by every reader of detective fiction I have encountered, it seems odd on second thought that the genre experienced in this way given its actual subject matter. In The Simple Art of Murder, Raymond Chandler points out that detective fiction is usually about murder and hence lacks the element of uplift (2). The world of the detective novel a place of untimely death, cruelty, suspicion, and betrayal. If detective fiction a literature of escape, why would anyone want to be transported to such anxious locales? Perhaps detective fiction produces its pleasurable effects by allowing us to feel that no matter how overwhelming our own situations seem, something much worse happening to someone else. But while the delights of schadenfreude might explain an individual's attraction to detective fiction, it hardly seems adequate to account for the tremendous popularity of the genre over the 150 years since Edgar Allan Poe presented the formula in his three C. Auguste Dupin tales. It clear that in the US the enduring popularity of the detective novel and the prominence of the detective genre in film, radio, and television are connected to the acceleration of real and perceived crime, violence, and surveillance over the course of the nineteenth and twentieth centuries. Furthermore, the genre deeply enmeshed with most of the thornier problems of the Victorian, modern, and postmodern eras, including gender roles and privileges, racial prejudice and the formation of racial consciousness, the significance and morality of wealth and capital, and the conflicting demands of privacy and social control. The mystery of mysteries, if you will, how a genre can achieve such wild success as a mode of relaxation while representing in a generally realistic style the most anxiety-producing issues and narra-

MODELLING OF THE NOISE SPECTRA OF AXIAL FLOW FANS IN A FREE FIELD

This paper presents a semi-empirical formula for predicting the noise spectra of axial flow fans in a free field. The basic assumption made in deriving this formula is that sound radiation from an axial flow fan in a free field is primarily due to the fluctuating pressure exerted on the fan blade surface. This fluctuating pressure is correlated to the lift force per unit length acting on the fan blade, and is subsequently approximated by pressure pulses that decay both in space and time. Accordingly, the radiated acoustic pressure is expressed in terms of superposition of contributions from these pressure pulses, and the line spectrum is obtained by taking a Fourier series expansion. To simulate the narrow and broad band sound spectra, a normal distribution-like shape function is designed which divides the frequency into consecutive bands centered at the blade passage frequency and its harmonics. The amplitude of this shape function at the center frequency of each band is unity but decays exponentially. The decay rate decreases with an increase in the number of bands. Thus, at high frequencies the narrow bands merge to form broad band-like spectra. The noise spectra thus obtained are compared with the measured ones from four different types of axial flow fans running under various conditions, and a favorable agreement in each case is obtained.

LSIパッケージの噴流冷却におけるヒートシンク形状の最適化

This paper describes the use of our previous study's prediction procedures for calculating thermal resistance and pressure drop. The procedures are used in the optimization of heat sink geometries for impingement air-cooling of LSI packages. Two types of heat sinks are considered: ones with longitudinal fins and ones with pin fins. We optimized the heat sink geometries by evaluating 16 parameters simultaneously. The parameters included fin thickness, spacing, and height. For the longitudinal fins, the optimal fin thicknesses were found to be between 0.12 and 0.15 mm, depending on which of the four types of fans were used. For pin fins, the optimal pin diameters were between 0.39 and 0.40 mm. Under constant pumping power, the optimal thermal resistance of the longitudinal fins was about 60% that of the pin fins. For both types of heat sinks, the optimal thermal resistance for four off-the-shelf fans was only slightly (maximum about 1%) higher than the theoretical optimum for the same pumping power. When manufacturing cost performance is considered, the most economical fin thickness and diameter are about 5 to 10 times higher than the optimal values calculated without respect for manufacturing costs. These values almost correspond to the actual limits of extrusion and press heat-sink manufacturing processes. © 1999 Scripta Technica, Heat Trans Asian Res, 28(2): 138–151, 1999

Permian (Upper Rotliegend) synsedimentary tectonics, basin development and palaeogeography of the southern North Sea

Abstract Upper Rotliegend sedimentation in the southern North Sea Basin (SNSB) was a response to complex synsedimentary tectonics and cyclical climatic changes. During the early Upper Rotliegend, faulting (?dextral strike-slip) resulted in the formation of a number of isolated sub-basins e.g. the Sole Pit, Silverpit and the Broad Fourteens, which were gradually united as a consequence of the progressive collapse of the Inde-Cleaver Bank High. Basin-margin tectonics controlled the evolution of the basin and the nature and distribution of the various types of alluvial fan and fan delta systems that evolved during pluvial climatic phases. Many of the earlier Upper Rotliegend fans display a systematic lateral displacement along synsedimentary faults. Along the Dowsing Fault Zone, ‘dry-type’ alluvial fans display a progressive northwestward migration with time. Also, fan deltas, sourced from the Texel-Ijsselmeer High, young progressively to the SE along the trend of the main faults. These systematic lateral displacements have been tentatively explained by invoking dextral oblique transfer of the source area relative to the depositional basin, within the context of a strike-slip tectono-sedimentary model. Alternatively, in an extensional model, the distribution pattern could be explained by sourcing the fans from both the footwall scarps and the transfer zones of dip-slip faults. A rapid decline in synsedimentary faulting, and a gradual change to more pluvial climatic conditions, resulted in the development of larger ‘wet type’ fans during the later part of the Upper Rotliegend time interval.

Sedimentation and erosion at the Weichselian ice-marginal zone near Golczewo, Northwestern Poland

The Golczewo end moraine was formed during the general ice-sheet recession after the Pomerania Phase of the Late Weichselian glaciation and represents a short period of steady state conditions at the ice-sheet margin. The end moraine is a SW-NE oriented zone formed of several, isolated, 10–15 m high ramparts, separated by low areas (‘gates’). The end moraine zone is located along the axis of the elevated Jurassic bedrock that much influenced the subglacial hydrology. The Golczewo end moraine is formed of two types of subaerial fan. Its major, and morphologically exposed part (hills), is represented by short, glacial-terminal fans. These fans have been partly eroded, especially at tunnel valley mouths. The eroded zones (‘gates’) have been filled with fluvial deposits forming flat sandur fans that extend across the end moraine foreland (plain). These morphological units (ramparts, ‘gates’ and sandur fans) which together form the end moraine zone, were formed synchronously. The ramparts are distinctly elongate hills, commonly asymmetrical, with steep proximal slopes. They comprise a complex sedimentary sequence that suggest alternating phases of sediment gravity flows and fluvial sheet floods. Flow tills indicate the ice-contact conditions. The ‘gates’ between hills and sandur fans are flat to gently inclined. They were formed by braided rivers, with sheet floods dominating at the fan apexes at the ‘gates’ and channelised braided rivers in more distal parts.