Distribution by Scientific Domains
Distribution within Medical Sciences

Kinds of Blades

  • disposable blade
  • grass blade
  • laryngoscope blade
  • leaf blade
  • rotor blade
  • scalpel blade
  • turbine blade

  • Terms modified by Blades

  • blade length
  • blade vibration

  • Selected Abstracts


    JOURNAL OF PHYCOLOGY, Issue 6 2006
    María Florencia Colombo-Pallotta
    Macrocystis pyrifera (L.) C. Agardh is a canopy-forming species that occupies the entire water column. The photosynthetic tissue of this alga is exposed to a broad range of environmental factors, particularly related to light quantity and quality. In the present work, photosynthetic performance, light absorption, pigment composition, and thermal dissipation were measured in blades collected from different depths to characterize the photoacclimation and photoprotection responses of M. pyrifera according to the position of its photosynthetic tissue in the water column. The most important response of M. pyrifera was the enhancement of photoprotection in surface and near-surface blades. The size of the xanthophyll cycle pigment pool (XC) was correlated to the nonphotochemical quenching (NPQ) of chl a fluorescence capacity of the blades. In surface blades, we detected the highest accumulation of UV-absorbing compounds, photoprotective carotenoids, ,XC, and NPQ. These characteristics were important responses that allowed surface blades to present the highest maximum photosynthetic rate and the highest PSII electron transport rate. Therefore, surface blades made the highest contribution to algae production. In contrast, basal blades presented the opposite trend. These blades do not to contribute significantly to photosynthetate production of the whole organism, but they might be important for other functions, like nutrient uptake. [source]

    Implementation, performance, and science results from a 30.7 TFLOPS IBM BladeCenter cluster

    Craig A. Stewart
    Abstract This paper describes Indiana University's implementation, performance testing, and use of a large high performance computing system. IU's Big Red, a 20.48 TFLOPS IBM e1350 BladeCenter cluster, appeared in the 27th Top500 list as the 23rd fastest supercomputer in the world in June 2006. In spring 2007, this computer was upgraded to 30.72 TFLOPS. The e1350 BladeCenter architecture, including two internal networks accessible to users and user applications and two networks used exclusively for system management, has enabled the system to provide good scalability on many important applications while being well manageable. Implementing a system based on the JS21 Blade and PowerPC 970MP processor within the US TeraGrid presented certain challenges, given that Intel-compatible processors dominate the TeraGrid. However, the particular characteristics of the PowerPC have enabled it to be highly popular among certain application communities, particularly users of molecular dynamics and weather forecasting codes. A critical aspect of Big Red's implementation has been a focus on Science Gateways, which provide graphical interfaces to systems supporting end-to-end scientific workflows. Several Science Gateways have been implemented that access Big Red as a computational resource,some via the TeraGrid, some not affiliated with the TeraGrid. In summary, Big Red has been successfully integrated with the TeraGrid, and is used by many researchers locally at IU via grids and Science Gateways. It has been a success in terms of enabling scientific discoveries at IU and, via the TeraGrid, across the US. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Shape Optimization of the Diffuser Blade of an Axial Blood Pump by Computational Fluid Dynamics

    ARTIFICIAL ORGANS, Issue 3 2010
    Lailai Zhu
    Abstract Computational fluid dynamics (CFD) has been a viable and effective way to predict hydraulic performance, flow field, and shear stress distribution within a blood pump. We developed an axial blood pump with CFD and carried out a CFD-based shape optimization of the diffuser blade to enhance pressure output and diminish backflow in the impeller,diffuser connecting region at a fixed design point. Our optimization combined a computer-aided design package, a mesh generator, and a CFD solver in an automation environment with process integration and optimization software. A genetic optimization algorithm was employed to find the pareto-optimal designs from which we could make trade-off decisions. Finally, a set of representative designs was analyzed and compared on the basis of the energy equation. The role of the inlet angle of the diffuser blade was analyzed, accompanied by its relationship with pressure output and backflow in the impeller,diffuser connecting region. [source]

    Peer Commmentaries on David H. Uttal's Seeing the big picture: map use and the development of spatial cognition

    Article first published online: 28 JUN 200
    Mark Blades, Young children's understanding of indirect sources of spatial information, p. 265 Roger M. Downs, The genesis of carto-gnosis, p. 267 Mary Gauvain, The instrumental role of maps in the development and organization of spatial knowledge, p. 269 Lynn S. Liben, Map use and the development of spatial cognition: seeing the bigger picture, p. 270 Kevin Miller, Mapping symbolic development, p. 274 Nora S. Newcombe, So, at last we can begin, p. 276 Herbert L. Pick Jr, Commentary on ,Seeing the big picture', p. 278 David R. Olson, Knowledge artifacts, p. 279 Barbara Tversky, What maps reveal about spatial thinking, p. 281 [source]

    15 Bitumen, Blades, and Beads: Prehispanic Craft Production and the Domestic Economy

    Elizabeth M. Brumfiel
    First page of article [source]

    Microstructure of a genuine Damascus sabre

    A. A. Levin
    Abstract The surface and cross-section of a genuine Damascus sword was characterised by means of wide-angle X-ray scattering techniques complemented by optical and transmisssion electron microscopy. Position-resolved X-ray phase analysis revealed that, unlike ferrite and martensite, the distribution of cementite is inhomogeneous in different spatial zones parallel to the cutting edge of the blade. For the first time a quantitative X-ray phase and texture analysis was made possible by averaging all spatial zones of the surface and the cross-section of the sword and applying the Rietveld method with code TOPAS. Differences concerning texture and structure characteristics of ferrite, martensite and cementite are discussed. More evidence for the structure of cementite nanowires is supplied. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Multidisciplinary approach to the treatment of an oblique crown,root fracture

    Anna-Louise Bate
    After removal of the fractured cusp, a provisional restorative build-up in this area was carried out, in order to carry out an endodontic treatment in a sterile environment. A glass fibre post and core were then constructed and over a 90-day period the tooth was extruded orthodontically by 4 mm. The periodontal fibres associated with this tooth were cut with a tiny surgical blade to help to prevent reintrusion of the tooth and achieve fine contouring of the gingival margins. The new tooth position was maintained with a retainer for a further 60 days and after a period with a provisional acrylic crown, a porcelain bonded crown was fitted. This case report demonstrates that such a multidisciplinary treatment approach to an oblique subgingival fracture is a reliable and predictable manner in which to save a tooth that would have otherwise been difficult, if not impossible, to restore with a resultant good long-term prognosis. [source]

    Mechanical removal of necrotic periodontal ligament by either Robinson bristle brush with pumice or scalpel blade.

    Histomorphometric analysis, scanning electron microscopy
    Abstract,,, One of the important factors accounting for successful delayed replantation of avulsed teeth is seemingly the type of root surface treatment. Removal of necrotic cemental periodontal ligament remnants may prevent the occurrence of external root resorption, which is the major cause of loss of teeth replanted in such conditions. The purpose of this study was to compare the efficacy of two mechanical techniques for removal of root-adhered periodontal ligament. Preservation or removal of the cementum layer concomitantly with these procedures was also assessed. Forty-five roots of healthy premolars extracted for orthodontic purposes were selected. After extraction, the teeth were kept dry at room temperature for 1 h and then immersed in saline for rehydration for an additional 10 min. Thereafter, the roots were assigned to three groups, as follows: group 1 (control) - the cemental periodontal ligament was preserved; group 2 - removal of the periodontal ligament by scraping root surface with a scalpel blade (SBS); group 3 - periodontal ligament remnants were removed using a Robinson bristle brush at low-speed with pumice/water slurry (RBP). The specimens were analysed histomorphometrically and examined by scanning electron microscopy. The quantitative and qualitative analyses of the results showed that the RBP technique was significantly more effective than the SBS technique for removal of the periodontal ligament remnants adhered to root surface. Both techniques preserved the cementum layer. [source]

    Donor Harvesting: A New Approach to Minimize Transection of Hair Follicles

    Damkerng Pathomvanich MD
    Background. There are several methods for harvesting donor hairs, including punch excision, single-bladed knife excision, and multibladed knife excision. All of these procedures are blind and thus result in transection of hair follicles. Transection of hair follicles during harvesting results in fewer follicles being available for transplantation, detrimentally affecting the final cosmetic result. Objective. To explore a new method of donor hair harvesting called "donor dissecting." This new procedure is an open technique because hair follicles are directly visualized during the harvesting process. Methods. The technique of donor dissecting utilizes a #15 scalpel blade to excise the donor hair ellipse from the occiput while maintaining meticulous hemostasis. This enables individual hair follicles to be visualized and protected from transection during the harvesting process. Once the donor ellipse is harvested, it is then further divided into individual mini- and micrografts using direct visualization of individual follicles to again prevent transection. Results. The technique of donor dissecting was utilized in 50 consecutive hair transplant patients. Utilizing this new technique, only 1.9% of hair follicles in the donor ellipse were transected during the harvesting process. The dissection of the donor ellipse 1.2% follicles being transected in the graft cutting process. Combining the donor dissection technique with dissection of the individual grafts, we were able to transect 1.59% of hair follicles harvested for transplantation. Conclusion. The technique of donor dissection minimizes the transection of hair follicles in the donor hair harvesting phase of hair transplantation. This technique is superior to the blind methods of donor harvesting which have been plagued by the problem of hair follicle transection. [source]

    Effect of canonical Wnt inhibition in the neurogenic cortex, hippocampus, and premigratory dentate gyrus progenitor pool

    Nina Solberg
    Abstract Canonical Wnt signaling is crucial for the correct development of both cortical and hippocampal structures in the dorsal telencephalon. In this study, we examined the role of the canonical Wnt signaling in the dorsal telencephalon of mouse embryos at defined time periods by inhibition of the pathway with ectopic expression of Dkk1. Transgenic mice with the D6-driven Dkk1 gene exhibited reduced canonical Wnt signaling in the cortex and hippocampus. As a result, all hippocampal fields were reduced in size. Neurogenesis in the dentate gyrus was severely reduced both in the premigratory and migratory progenitor pool. The lower number of progenitors in the dentate gyrus was not rescued after migration to the subgranular zone and thus the dentate gyrus lacked the entire internal blade and a part of the external blade from postnatal to adult stages. Developmental Dynamics 237:1799,1811, 2008. © 2008 Wiley-Liss, Inc. [source]

    State criterion of wind turbine generator operation using tower shadow effect (Part 2)

    Tadashi Naitoh
    Abstract In order to obtain wind energy effectively, the pole-change-type induction generators are used as the wind turbine generators. Otherwise, the pole-change-type induction generator causes the voltage dips at pole changing time. To maintain the power quality, it is important to know the state change of the generator operation. Therefore, the authors have studied a state criterion of generator using the tower shadow effect, which is the active power oscillation caused by a rotation torque drop when the tower and the turbine blade overlap each other. In this paper, an improved identification method of oscillation frequency, which is the criterion of wind turbine generator operation, is proposed. The proposed method is applied to measured data and good results are obtained. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 25,31, 2008; Published online in Wiley InterScience ( DOI 10.1002/eej.20395 [source]

    Hydrodynamic Modulation Voltammetry with a Dual Disk Chopped Flow-Microjet Electrode (CF-MJE)

    ELECTROANALYSIS, Issue 18 2003
    Nafeesa Simjee
    Abstract A novel form of hydrodynamic modulation voltammetry (HMV) is described, based on the periodic variation of mass transport in a microjet electrode (MJE) system, in combination with phase-sensitive detection techniques. In the configuration developed, a jet of solution is fired from a nozzle that is aligned directly over the surface of a dual disk Pt-Pt ultramicroelectrode (UME). The potential at each electrode is controlled separately. A rotating blade, positioned between the nozzle and the UME probe, is used to periodically interrupt flow to the electrode surface, resulting in modulation of the overall mass transfer rate between two defined extremes. The use of a dual disk UME enables two transport-limited current signals to be recorded simultaneously, one for the analyte of interest, and the other for a ,reference species' (oxygen for the studies described herein). The latter current response corresponds to the variation in mass transport rate in the chopped flow (CF) arrangement and is used as the signal for phase sensitive detection of the analyte current. Studies of potassium hexachloroiridate (III) [IrCl] oxidation in aqueous solution are used to demonstrate the capabilities of the technique. HMV in the CF-MJE arrangement allows quantitative concentration measurements, down to at least 5×10,7,M. [source]

    Uptake and translocation of p,p,-dichlorodiphenyldichloroethylene supplied in hydroponics solution to Cucurbita

    Martin P. N. Gent
    Abstract Field studies show shoots of zucchini (Cucurbita pepo L.) accumulate various hydrophobic contaminants from soil, although many other plants do not, including cucumber (Cucumis sativus L.). To investigate the mechanism for this uptake, we presented p,p,-dichlorodiphenyldichloroethylene (DDE) to these two species in hydroponics solution. A mixture of DDE bound to TenaxÔ beads stirred with a solution of water passing through a reservoir provided a flowing solution containing DDE at approximately 2 ,g/L for many weeks duration. Approximately 90% of the DDE supplied in solution was adsorbed on the roots of both cucumber and zucchini. Less than 10% of the sorbed DDE was released subsequently when clean solution flowed past these contaminated roots for 9 d. The shoots of both species accumulated DDE, but the fraction that moved from the roots to the shoot in zucchini, ranging from 6 to 27% in various trials, was 10-fold greater than that in cucumber, 0.7 to 2%. The gradient in DDE concentration in zucchini tissues was in the order root > stem > petiole > leaf blade, indicating the movement was through the xylem in the transpiration stream. Some DDE in leaf blades might have been absorbed from the air, because the concentration in this tissue varied less with time, position in trough, or species, than did DDE in stems and petioles. The remarkable ability of zucchini to translocate DDE could not be attributed to differences in tissue composition, growth rate, distribution of weight among plant parts, or in the leaf area and rate of transpiration of water from leaves. Some other factor enables efficient translocation of hydrophobic organic contaminants in the xylem of zucchini. [source]

    Fungal biodiversity, pollen morphology and leaf surface of some native species in Egypt

    FEDDES REPERTORIUM, Issue 1 2001
    S. I. I. Abdel-Hafez
    Five native species of the flora of Egypt: Adonis dentata Delile, Ranunculaceae; Papaver dubium L., Papaveraceae; Matthiola longipetala (Vent.) DC., Brassicaceae; Malva parviflora L., Malvaceae; and Erodium laciniatum (Cav.) Willd., Geraniaceae have been investigated morphologically, palynologically and mycologically. The total counts of phyllosphere fungi fluctuated between 223 and 388 colonies/100 leaf segments giving maximum on Malva parviflora followed by Matthiola longipetala, Erodium laciniatum, Papaver dubium and Adonis dentata. The widest spectrum of genera (20) and species (39 and l variety) was recorded on Malva parviflora and the narrowest on Adonis dentata (9, 14). Sixty species and one variety belonging to 27 genera were collected from leaves (24 genera and 56 species and 1 variety) and anthers/pollen (16 genera and 27 species) of the five studied plants with the most frequently species were some members of Alternaria, Cladosporium, Fusarium and Mucor. Members of Aspergillus and Penicillium were prevalent only on leaves of Matthiola longipetala and Malva parviflora, while these members were infrequently recorded on leaf surfaces of Adonis dentata and Papaver dubium. Results revealed that density of hairs on the leaf surface and size of leaf blade, almost seem to be the most reliable factors of the biodiversity of the fungal spores on the studied taxa. On the other hand, reticulate or striate pollen surface had a wider spectrum of fungal biodiversity and higher densities of spores compared with echinate and scabrate surface. Pilz-Biodiversität, Pollen-Morphologie und die Blattoberfläche einiger einheimischer Arten in Ágypten Aus der Flora Ágyptens wurden die fünf einheimischen Arten Adonis dentata Delile, Ranunculaceae; Papaver dubium L., Papaveraceae; Matthiola longipetala (Vent.) DC., Brassicaceae; Malva parviflora L., Malvaceae; und Erodium laciniatum (Cav.) Willd., Geraniaceae morphologisch, palynologisch und mykologisch untersucht. Die Gesamtzahl an phyllosphären Pilzen schwankte zwischen 223 und 388 Kolonien/100 Blattsegementen. Das Maximum lag bei Malva parviflora, gefolgt von Matthiola longipetala, Erodium laciniatum, Papaver dubium und Adonis dentata. Das größte Spektrum an Gattungen (20) und Arten (39 und 1 Varietät) wurde bei Malva parviflora verzeichnet, das Minimum hingegen bei Adonis dentata (9, 14). An den fünf Arten wurden insgesamt 60 Arten und eine Varietät aus 27 Gattungen an Blättern (24 Gattungen, 56 Arten und eine Varietät) und Antheren/Pollen (16 Gattungen, 27 Arten) verzeichnet. Die häufigsten Arten gehörten zu den Gattungen Alternaria, Cladosporium, Fusarium und Mucor. Arten von Aspergillus und Penicillium wurden nur an Blättern von Matthiola longipetala und Malva parviflora nachgewiesen, während sie an den Blattoberflächen von Adonis dentata und Papaver dubium seltener waren. Aus den erzielten Resultaten ergibt sich, dass die Dichte des Haarbesatzes an der Blattoberfläche und die Größe der Blattspreite die entscheidenden Faktoren zur Biodiversität der Pilzsporen an den untersuchten Taxa sind. Anderseits kann man sagen, dass reticulate und striate Pollen im Vergleich zu einer echinaten und skabraten Oberfläche ein größeres Spektrum der Pilz-Biodiversität und eine höhere Sporendichte aufwiesen. [source]

    Temporal, spatial and biotic variations in extrafloral nectar secretion by Macaranga tanarius

    FUNCTIONAL ECOLOGY, Issue 6 2000
    Heil M.
    Abstract 1Many plants produce extrafloral nectar (EFN) to nourish ants and other animals which defend them against herbivores. We aimed to find reasons for the high variability in amounts of EFN produced by most plant species. We investigated the influence of several biotic and abiotic factors (time of day, leaf age, nectar removal and leaf damage) on secretion rates of EFN in the common south-east Asian pioneer tree species, Macarangatanarius (L.) Muell. Arg. 2In most experiments leaves were washed with pure water and bagged in nets to protect them against nectar-collecting insects, and nectar was collected and quantified 24 h later. Six soluble sugars and up to eight amino acids were detected in nectar samples derived from untreated, field-grown plants. Total amounts of soluble substances varied more than the relative composition of EFN. 3Nectar secretion rates were highest on young, expanded leaves. A diurnal pattern with a secretion peak in the first 2 h after dusk was detected in the field. Nectar removal had a positive effect and its accumulation a negative effect on further EFN production. Artificial leaf damage (punching leaves with a needle or removing parts of the leaf blade with scissors) led to a significant induction of EFN production for the next 3 days. 4Extrafloral nectar of M. tanarius was secreted in complex patterns influenced by different biotic and abiotic factors; its production appeared to be adapted temporally and spatially in order to ensure optimal use of invested resources. [source]

    Heat transfer in high-aspect-ratio rectangular passage with skewed ribs

    Takanari Okamura
    Abstract The heat transfer characteristics and flow behavior in a rectangular passage with two opposite 45° skewed ribs for turbine rotor blade have been investigated for Reynolds numbers from 7800 to 19,000. In this blade, the spanwise coolant passage at the trailing edge region whose thickness is very thin is chosen, so the channel aspect ratio (=width/height of channel) is extremely high, 4.76. Therefore the heat transfer experiment in the high-aspect-ratio cooling channel was performed using thermochromic liquid crystal and thermocouples. Furthermore, the calculation of flow and heat transfer was carried out using CFD analysis code to understand the heat transfer experimental results. The enhanced heat transfer coefficients on the smooth side wall at the rib's leading end were the same level as those on the rib-roughened walls. © 2002 Scripta Technica, Heat Trans Asian Res, 31(2): 89,104, 2002; DOI 10.1002/htj.10018 [source]

    A study of lightning risk

    Takatoshi Shindo Senior Member
    Abstract It is important to establish a lightning risk management scheme for rational insulation design. In this paper, lightning risk assessment is carried out for a customer facility and a wind turbine blade. The calculated values of lightning risk agree with field experiences. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]

    A new lightning protection system for wind turbines using two ring-shaped electrodes

    Yasuda Yoh Member
    Abstract Wind turbines are often struck by lightning because of their special shape, their tall structure and their being placed in the open air. Besides seriously damaging the blades, lightning results in accidents in which low-voltage and control circuit breakdowns frequently occur in many wind farms worldwide. Although some reports, such as IEC TR61400-24 and NREL SR-500-31115, have indicated a methodology for protection against such accidents, a standard solution to these problems remains to be established. The author, focusing on a method for protection of low-voltage and control circuits in a wind tower, proposed a new lightning protection system with two ring-shaped electrodes attached to the wind turbine. The proposed system has two ring-shaped electrodes of several meters diameter, one vertically attached to the nose cone and the other laterally placed at the top of the wind tower lying just below the nacelle. The pair of rings is arranged with a narrow gap of no more than 1 m in order to avoid mechanical friction during rotation of the blades and the nacelle's circling. When lightning strikes a blade, the current reaches the upper ring from a receptor through a conductive wire. Then, the electric field between the two rings becomes high and finally sparks over and the lightning current flows downwards. The current propagates along the lower ring and the grounding wire, which is arranged outside of the wind tower rather than inside, and is safely led to a grounding electrode placed far enough away from the tower's grounding system. In this paper, the author describes a basic experiment using a 1/100 downsized model, and also discusses the concept behind the present system. The result of the downsized experiment provides evidence of an effective advantage for lightning protection. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]

    The Usefulness of Design of Experimentation in Defining the Effect Difficult Airway Factors and Training Have on Simulator Oral,Tracheal Intubation Success Rates in Novice Intubators

    Frank Thomas MD
    Abstract Objectives:, This exploratory study examined novice intubators and the effect difficult airway factors have on pre- and posttraining oral,tracheal simulation intubation success rates. Methods:, Using a two-level, full-factorial design of experimentation (DOE) involving a combination of six airway factors (curved vs. straight laryngoscope blade, trismus, tongue edema, laryngeal spasm, pharyngeal obstruction, or cervical immobilization), 64 airway scenarios were prospectively randomized to 12 critical care nurses to evaluate pre- and posttraining first-pass intubation success rates on a simulator. Scenario variables and intubation outcomes were analyzed using a generalized linear mixed-effects model to determine two-way main and interactive effects. Results:, Interactive effects between the six study factors were nonsignificant (p = 0.69). For both pre- and posttraining, main effects showed the straight blade (p = 0.006), tongue edema (p = 0.0001), and laryngeal spasm (p = 0.004) significantly reduced success rates, while trismus (p = 0.358), pharyngeal obstruction (p = 0.078), and cervical immobilization did not significantly change the success rate. First-pass intubation success rate on the simulator significantly improved (p = 0.005) from pre- (19%) to posttraining (36%). Conclusions:, Design of experimentation is useful in analyzing the effect difficult airway factors and training have on simulator intubation success rates. Future quality improvement DOE simulator research studies should be performed to help clarify the relationship between simulator factors and patient intubation rates. ACADEMIC EMERGENCY MEDICINE 2010; 17:460,463 © 2010 by the Society for Academic Emergency Medicine [source]

    Effect of incidence angle with wake passing on a film cooled leading edge: A numerical study

    F. Montomoli
    Abstract This work presents the numerical study of a film-cooled blade under the influence of wake passing at different incidence angles. The film cooling technology has been proven to be effective to increase the blade life of first turbine stages. However, the leading edge is affected by an high heat transfer rate and cooling this region is difficult. Moreover, separated regions downstream the coolant injection increases the local heat transfer coefficient and can have a detrimental effect in terms of airfoil life. This work analyses how the flow field is affected by the wake passing at different incidence angles (,5, 0, 5) and the impact on heat transfer coefficient. The test case is a linear cascade with two rows of cylindrical holes at the leading edge. Two different holes arrangements are compared in terms of film cooling structures, namely AGTB-B1 and AGTB-B2 with 0 and 45, spanwise inclination. The numerical results show a good agreement with the experiments. A deeper investigation is carried out on AGTB-B1. The results obtained show that the wake passing and the incidence angle have a strong effect on coolant jets. In particular, there is a significative impact on coolant redistribution near the leading edge. The wake passing has a stronger effect on pressure side, mainly at negative incidence. The predictive approach is based on an U-RANS in-house CFD solver using a conventional two-equations closure. In order to avoid extra turbulence production, critical in the leading edge region, the turbulence model incorporates an extra algebraic equation that enforces a realizability constraint. The unsteady formulation is based on a dual time stepping approach with a sliding plane between the moving bars and the cascade. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Closed-loop identification of the time-varying dynamics of variable-speed wind turbines

    J. W. van Wingerden
    Abstract The trend with offshore wind turbines is to increase the rotor diameter as much as possible to decrease the costs per kWh. The increasing dimensions have led to the relative increase in the loads on the wind turbine structure. Because of the increasing rotor size and the spatial load variations along the blade, it is necessary to react to turbulence in a more detailed way: each blade separately and at several separate radial distances. This combined with the strong nonlinear behavior of wind turbines motivates the need for accurate linear parameter-varying (LPV) models for which advanced control synthesis techniques exist within the robust control framework. In this paper we present a closed-loop LPV identification algorithm that uses dedicated scheduling sequences to identify the rotational dynamics of a wind turbine. We assume that the system undergoes the same time variation several times, which makes it possible to use time-invariant identification methods as the input and the output data are chosen from the same point in the variation of the system. We use time-invariant techniques to identify a number of extended observability matrices and state sequences that are inherent to subspace identification identified in a different state basis. We show that by formulating an intersection problem all states can be reconstructed in a general state basis from which the system matrices can be estimated. The novel algorithm is applied on a wind turbine model operating in closed loop. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Empirical Distribution Models for Escherichia coli 57:H7 in Ground Beef Produced by a Mid-size Commercial Grinder

    R.A. Flores
    ABSTRACT: The purpose of this research was to develop empirical models that describe the amount and distribution of ground beef contaminated with Escherichia coli O157:H7 when a contaminated beef trim is introduced into a batch of uncontaminated beef before processing in a mid-size commercial grinder (34 g/s). A beef trim was inoculated with a rifampacin-resistant strain of E. coli O157:H7 and added to a batch of noncontaminated trims at the grinding step. To study the distribution of the E. coli O157:H7rif in the ground beef, 6 treatments with different inoculum levels (1 to 6 log10 colony-forming units [CFU]) were tested. Removal or pick up of the residual contamination with E. coli O157:H7rif left in the grinder was evaluated. E. coli O157:H7rif was detected in 9% to 86% of the total ground beef for the 1 to 6 log10 CFU inoculum levels, respectively. E. coli O157:H7rif contamination was detected in the collar that fixes the grinder's die and blade to the hub. An exponential algorithm described the relationship between the quantities of ground beef containing E. coli O157:H7rif and the inoculum level (R2= 0.82). Distribution models based on a Chi-squared algorithm were developed for each inoculum level describing the contamination level as a function of the batch fraction processed (R2= 0.81 to 0.99). The results of this study corroborate that when beef processors test for pathogenic contamination in a mid-scale grinder, they should test the beef residues in the collar that fixes the grinder's die and blade to the hub. [source]

    The effect of mixer properties and fill level on granular flow in a bladed mixer

    AICHE JOURNAL, Issue 2 2010
    Brenda Remy
    Abstract The discrete element method was used to study the effect of mixer properties and fill level on the granular flow of monodisperse, cohesionless spheres in a bladed mixer. For fill levels just covering the span of the blades, a three-dimensional (3-D) recirculation zone develops in front of the blades, which promotes vertical and radial mixing. Increasing fill level reduces the size of the recirculation zone, decreases bed dilation and hinders particle diffusivities. However, above a critical fill level, the behavior of the particles within the span of the blade is found to be invariant of fill level. At low-fill levels, the pressure within the particle bed varies linearly with bed height and can be approximated by hydrostatics. At higher fill levels, a constant pressure region develops within the span of the blades due to the angled pitch of the blades. Cylinder wall friction is shown to significantly influence granular behavior in bladed mixers. At low-wall friction, the 3-D recirculation zone observed for high-wall friction conditions does not develop. High-wall friction leads to an increase in convective and diffusive particle mixing. Shear stresses are shown to be a function of wall friction. Blade position along the vertical axis is shown to influence flow patterns, granular temperature and stress. The effect of increasing the mixer diameter at a constant particle diameter was also studied. When the mixer diameter is larger than a critical size such that wall effects are minimized, the observed granular behavior follows simple scaling relations. Particle velocities and diffusivities scale linearly with mixer size and blade speed. Normal and shear stress profiles are found to scale linearly with the total weight of the particle bed. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source]

    Continuous process for production of hydrogenated nitrile butadiene rubber using a Kenics® KMX static mixer reactor

    AICHE JOURNAL, Issue 11 2009
    Chandra Mouli R. Madhuranthakam
    Abstract A continuous process for hydrogenating nitrile butadiene rubber (NBR) was developed and its performance was experimentally investigated. A Kenics® KMX static mixer (SM) is used in the process as a gas,liquid reactor in which gaseous hydrogen reacts with NBR in an organic solution catalyzed by an organometallic complex such as an osmium complex catalyst. The Kenics® KMX SM was designed with 24 mixing elements with 3.81 cm diameter and arranged such that the angle between two neighboring elements is 90°. The internal structure of each element is open blade with the blades being convexly curved. The dimensions of the SM reactor are: 3.81 cm ID 80 S and 123 cm length and was operated cocurrently with vertical upflow. The NBR solutions of different concentrations (0.418 and 0.837 mol/L with respect to [CC]) were hydrogenated by using different concentrations of the osmium catalyst solution at various residence times. The reactions were conducted at a constant temperature of 138°C and at a constant pressure of 3.5 MPa. From the experimental results, it is observed that a conversion and/or degree of hydrogenation above 95% was achieved in a single pass from the designed continuous process. This is the first continuous process for HNBR production that gives conversions above 95% till date. Optimum catalyst concentration for a given mean residence time to achieve conversions above 95% were obtained. Finally, a mechanistic model for the SM reactor performance with respect to hydrogenation of NBR was proposed and validated with the obtained experimental results. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

    Discrete element simulation of free flowing grains in a four-bladed mixer

    AICHE JOURNAL, Issue 8 2009
    Brenda Remy
    Abstract Numerical simulations of granular flow in a cylindrical vessel agitated by a four-blade impeller were performed using the discrete element method. Velocity, density, and stress profiles within the mixer displayed a periodic behavior with a fluctuation frequency equal to that of the blade rotation. Blade orientation was found to affect flow patterns and mixing kinetics. For an obtuse blade pitch orientation, a three-dimensional recirculation zone develops in-front of the blade due to formation of heaps where the blades are present. This flow pattern promotes vertical and radial mixing. No recirculation zone was observed when the blade orientation was changed to an acute blade pitch. The system's frictional characteristics are shown to strongly influence the granular behavior within the mixer. At low friction coefficients, the 3-D recirculation in front of the obtuse blade is not present reducing convective mixing. Higher friction coefficients lead to an increase in granular temperature which is associated with an increase in diffusive mixing. Normal and shear stresses were found to vary with mixer height with maximum values near the bottom plate. Additionally, a strong dependence between the magnitude of the shear stresses and the friction coefficient of the particles was found. The stress tensor characteristics indicate that the granular flow in our simulations occurs in the quasi-static regime. At the same time, the averaged pressure was found to vary linearly with bed height and could be predicted by a simple hydrostatic approximation. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

    The initiation and development of metamorphic foliation in the Otago Schist, Part 1: competitive oriented growth of white mica

    Abstract The 3D shape, size and orientation data for white mica grains sampled along two transects of increasing metamorphic grade in the Otago Schist, New Zealand, reveal that metamorphic foliation, as defined by mica shape-preferred orientation (SPO), developed rapidly at sub-greenschist facies conditions early in the deformation history. The onset of penetrative strain metamorphism is marked by the rapid elimination of poorly oriented large clastic mica in favour of numerous new smaller grains of contrasting composition, higher aspect ratios and a strong preferred orientation. The metamorphic mica is blade shaped with long axes defining the linear aspect of the foliation and intermediate axes a partial girdle about the lineation. Once initiated, foliation progressively intensified by an increase in the aspect ratio, size and alignment of grains, although highest grade samples within the chlorite zone record a decrease in aspect ratio and reduction in SPO strength despite continued increase in grain size. These trends are interpreted in terms of progressive competitive anisotropic growth of blade-shaped grains so that the fastest growth directions and blade lengths tend to parallel the extension direction during deformation. The competitive nature of mica growth is indicated by the progressive increase in size and resultant decrease in number of metamorphic mica with increasing grade, from c. 1000 relatively small mica grains per square millimetre of thin section at lower grades, to c. 100 relatively large grains per square millimetre in higher grade samples. Reversal of SPO intensity and grain aspect ratio trends in higher grade samples may reflect a reduction in the strain rate or reduction in the deviatoric component of the stress field. [source]


    JOURNAL OF PHYCOLOGY, Issue 1 2010
    Markus Molis
    Little is known about the indirect effects of nonlethal grazing impacts in mesograzer,seaweed interactions. Using laboratory experiments, the effect of grazing by the seasonally abundant kelp-associated gastropod Lacuna vincta on subsequent kelp consumption by one kelp-associated (Idotea granulosa) and one nonassociated species of isopod (I. emarginata) was determined. Measurements of the toughness and elemental composition of different parts of the sporophyte of Laminaria digitata (Huds.) J. V. Lamour., as well as grazer-induced changes in the palatability of the blade, were conducted to explore possible mechanisms of indirect effects. In situ grazing pressure was the highest between July and September, with the blade being the preferred part of the kelp sporophyte, despite missing differences in the elemental composition among kelp parts. The laboratory experiments supported our hypotheses in that kelp consumption by both species of isopods was lower on intact than on L. vincta,damaged areas of the blade. This pattern was not caused by grazing-induced changes in blade palatability. Instead, the observed increase in isopod consumption following grazing by L. vincta resulted more likely from the combined effects of a reduction in the toughness of L. vincta,damaged kelp blades and some unknown gastropod cue(s). These results suggest that kelp-associated and nonassociated mesograzers may benefit from the nonlethal grazing impact of L. vincta due to changes in physical traits of the seaweed. Thus, the nonlethal grazing impact by one species of mesograzer can positively modify the trophic interactions between kelp and other potential competitors, suggesting that the interactions among mesograzers might be more complex than previously assumed. [source]

    Physiological Performance of Asymptomatic and Yellow Leaf Syndrome-affected Sugarcanes in Venezuela

    Serological analyses revealed the presence of the sugarcane yellow leaf virus (ScYLV) in asymptomatic (S,) and symptomatic (S+) yellow leaf syndrome-affected sugarcane plants of the cultivars PR.692176, C.323,68, V.64,10, V.71,47, V.75,6, SP.72,2086, SP.72,1210, SP.74,2005, C.323,68, B.80,549 and B.82,363. Tests for the presence of the sugarcane yellows phytoplasma, carried out by Dr P. Jones (IACR-Rothamsted), gave negative results in all cultivars. Physiological analyses were performed in the top visible dewlap (TVD) leaf of S, and S+ plants of the cultivar PR.692176. All plants were at the second ratoon and flowering. When compared with S, plants, the S+ plants showed: (a) a marked reduction in the area of the leaf and internodes; (b) a high accumulation of total reducing sugars (TRS), glucans and ,-amino-N in the leaf blade and of TRS in the corresponding leaf sheath; (c) a decrease in the chlorophyll, phosphorus and nitrogen content in the leaf; (d) the disappearance of the leaf diurnal fluctuations in TRS accumulation and export as well as the daily oscillations of TRS and glucans between dawn and dusk; and (e) major ultrastructural alterations in the companion cells of the phloem, including the accumulation of ScYLV particles in the cytoplasm. In S, plants, none of the growth and physiological alterations described above were observed, in spite of the high density of ScYLV particles in the cytoplasm. The location of S, and S+ plants close to each other without a discernible pattern of distribution in plots subjected to optimal irrigation and fertilization rule out the possibility that environmental conditions underlay the appearance of symptoms. In plots under severe drought for 3 months, however, all S, plants become S+. Symptom expression did not affect the acid phosphatase activity in the rhizosphere of S+ plants. [source]

    The use of micro-Raman spectroscopy in architectural paint analysis

    E. Kendix
    Abstract Architectural paint analysis is an important technique for establishing the palette of historical paint colours, and reconstructing how a room or a facade might have looked at an earlier time. In its simplest form, it has often been achieved by using paint scrapes, which involves revealing a stepped sequence of layers of paint using a blade or solvents. Cross-sections are used as an alternative to, or in combination with, scrapes. Mounted cross-sections can be examined by optical microscopy. Accumulated layers of paint, wallpaper or other applied decorative finishes can be defined from their textures and colours. Knowledge of the identity of the components in paint layers can be used to reconstruct a certain paint and also to date the paint layers. It is demonstrated that micro-Raman spectroscopy combined with optical microscopy and low-vacuum scanning electron microscopy,energy-dispersive spectrometry are versatile tools for the characterization of pigments and fillers in cross-sections from architectural decorations. The paper gives an example of the examination of an interior decoration from a historical building. Copyright © 2004 John Wiley & Sons, Ltd. [source]


    ABSTRACT Breeding specialty soybeans for the soyfood market requires proper methodology in evaluation of seed quality attributes. In this study, efficient methods that could be potentially used for testing soybean seed hardness were developed by examining different instruments and seed parameters. Five food-grade soybean genotypes with different seed sizes were used to determine seed water-absorption capacity and hardness. Water absorption capacity was expressed by swell ratios for seed weight, seed dimension, and volume of water changes before and after soaking. Seed hardness test was conducted by a one-bite method using a food texture analyzer equipped with five different probes. The results showed that hardness testing by a 75 mm cylinder with 10 steamed seeds, single blade with five steamed seeds, and shear cell with 30 g steamed seeds produced dependable and consistent results with low coefficient of variance. However, shear cell may not be practical for early plant selection in a breeding program due to a relatively large sample requirement. Seed size can be used as indirect selection indicators for seed hardness. PRACTICAL APPLICATIONS Seed hardness is an important factor in determining soybean suitability for natto production. This study used two texture analyzers equipped with five different probes to test hardness of five soybean genotypes with different seed size. The methodologies for testing the seed texture of soybean have been established, which can help regulate the seed hardness testing for commercial production and provide consistent hardness references for natto breeding programs and the seed industry. [source]