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Lift
Kinds of Lift Terms modified by Lift Selected AbstractsDo collisions inside the collision cell play a relevant role in CID-LIFT experiments?,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2007Gloriano Moneti Abstract Collision experiments are a valid approach to characterize the ionic species generated by matrix assisted laser desorption ionization (MALDI). When a time-of-flight analyzer is employed, three different approaches are available for these experiments: the postsource decay (PSD), the LIFT and the MALDI-TOF/TOF. The last two are of particular interest because of the overcoming of the PSD problems related to mass calibration of the product ion spectra. Experiments performed by LIFT on linear or cyclic peptides, in presence or in absence of collision gas in the collision cell, gave evidence of an unexpected behavior: the two spectra were practically superimposable, and in the former case only a few new fragmentation channels were activated with low yield. These results mean that the selected ion exhibits a large amount of internal energy, capable of promoting fragmentation processes in the time window corresponding to the flight time between ion source and the acceleration electrode placed after the collision cell. Experiments performed by varying the plume density show that this internal energy uptake occurs in the expanding plume, through multiple collisions. The LIFT data have been compared with those achieved by collisions of ESI-generated [MH]+ ions of angotensin II performed under ,in-source' conditions and by triple-quadrupole experiments. The obtained results show a strong similarity among the spectra, indicating that the internal energy uptake in a MALDI source is comparable with that of 40-eV ions colliding with Ar in a triple-quadrupole instrument. Copyright © 2006 John Wiley & Sons, Ltd. [source] Neck Lift by JOEL J. FELDMAN, MDDERMATOLOGIC SURGERY, Issue 3 2008WILLIAM P. COLEMAN III MD No abstract is available for this article. [source] A Percutaneous Approach to Eyebrow Lift: The Salvadorean OptionDERMATOLOGIC SURGERY, Issue 8 2003Enrique Hernandez-Perez MD Background Surgical eyebrow lift can result in a number of complications. A nonsurgical simple method of lifting the brow is presented. Objective To raise the eyebrows using a simple, quick, and noninvasive approach. Methods Twenty-nine patients, 27 women and 2 men, whose ages varied from 24 to 56 years (mean of 32 years) were included in the study. Preoperative and postoperative photographs were taken. In two patients, brow suspension was performed at the time of blepharoplasty. Informed consent was signed by all of the patients. For measuring the degree of satisfaction of the patients, we gave to them a sheet grading it from one to three (with one being the least satisfactory). Local anesthesia (1% lidocaine, 1:400,000 epinephrine), a conveniently sized Keith needle, and prolene 3/0 sutures were used. Results Satisfying results were obtained in all cases. The only problem encountered in two patients was temporary edema, and it settled in a few days. Conclusion This is a very simple, quick, and noncomplicated method of raising the eyebrows. It can be repeated, revised easily, or combined with other modalities, such as peels, topical tretinoin, oral isotretinoin, fat injection, Goretex, and Botox as part of a facial rejuvenation program. [source] Sinus Lift Using a Nanocrystalline Hydroxyapatite Silica Gel in Severely Resorbed Maxillae: Histological Preliminary StudyCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 2009Luigi Canullo DDS ABSTRACT Purpose: The aim of this preliminary study was to evaluate histologically a nanocrystalline hydroxyapatite silica gel in maxillary sinus floor grafting in severely resorbed maxillae. Materials and Methods: A total of 16 consecutive patients scheduled for sinus lift were recruited during this study. Patients were randomly divided in two groups, eight patients each. In both groups, preoperative residual bone level ranged between 1 and 3 mm (mean value of 2.03 mm). No membrane was used to occlude the buccal window. Second surgery was carried out after a healing period of 3 months in Group 1 and 6 months in Group 2. Using a trephine bur, one bone specimen was harvested from each augmented sinus and underwent histological and histomorphometric analysis. Results: Histological analysis showed significant new bone formation and remodeling of the grafted material. In the cores obtained at 6 months, regenerated bone, residual NanoBone, and bone marrow occupied respectively 48 ± 4.63%, 28 ± 5.33%, and 24 ± 7.23% of the grafted volume. In the specimens taken 3 months after grafting, mean new bone was 8 ± 3.34%, mean NanoBone was 45 ± 5.10%, and mean bone marrow was 47 ± 6.81% of the bioptical volume. Conclusions: Within the limits of this preliminary prospective study, it was concluded that grafting of maxillary sinus using nanostructured hydroxyapatite silica gel as only bone filler is a reliable procedure also in critical anatomic conditions and after early healing period. [source] Combination Surgical Lifting with Ablative Laser Skin Resurfacing of Facial Skin: A Retrospective AnalysisDERMATOLOGIC SURGERY, Issue 9 2004Tina S. Alster MD Background. Cutaneous aging is manifested by rhytides, dyschromias, and skin laxity. Ablative laser skin resurfacing can effectively improve many signs of skin aging; however, the photoaged patient with facial laxity often requires a surgical lifting procedure in order to obtain optimal results. Concerns with delayed or impaired wound healing has led to reluctance to perform both procedures simultaneously. Objective. To report the clinical results and side effect profiles after concomitant surgical facial lifting procedures and ablative carbon dioxide or erbium:YAG laser resurfacing in a series of patients. Methods. A retrospective analysis and chart review was performed in 34 consecutive patients who underwent combination CO2 or erbium:YAG laser skin resurfacing and surgical lifting procedures, including S-lift rhytidectomy, blepharoplasty, and brow lift. Side effects and complication rates were tabulated. Results. The side effect profile of the combined surgical-laser procedures was similar to that reported after a laser-only procedure. The most common side effect was transient hyperpigmentation which occurred in 20.6% of treated patients. None of the patients experienced delayed reepithelialization, skin necrosis, or prolonged healing times. Conclusions. Concurrent laser skin resurfacing and surgical lifting of facial skin maximizes aesthetic results without increased incidence of adverse effects. Patients benefit from the consolidation of anesthesia and convalescent times as well as enhanced global clinical outcomes. [source] A Percutaneous Approach to Eyebrow Lift: The Salvadorean OptionDERMATOLOGIC SURGERY, Issue 8 2003Enrique Hernandez-Perez MD Background Surgical eyebrow lift can result in a number of complications. A nonsurgical simple method of lifting the brow is presented. Objective To raise the eyebrows using a simple, quick, and noninvasive approach. Methods Twenty-nine patients, 27 women and 2 men, whose ages varied from 24 to 56 years (mean of 32 years) were included in the study. Preoperative and postoperative photographs were taken. In two patients, brow suspension was performed at the time of blepharoplasty. Informed consent was signed by all of the patients. For measuring the degree of satisfaction of the patients, we gave to them a sheet grading it from one to three (with one being the least satisfactory). Local anesthesia (1% lidocaine, 1:400,000 epinephrine), a conveniently sized Keith needle, and prolene 3/0 sutures were used. Results Satisfying results were obtained in all cases. The only problem encountered in two patients was temporary edema, and it settled in a few days. Conclusion This is a very simple, quick, and noncomplicated method of raising the eyebrows. It can be repeated, revised easily, or combined with other modalities, such as peels, topical tretinoin, oral isotretinoin, fat injection, Goretex, and Botox as part of a facial rejuvenation program. [source] Herbivory patterns in mature sugar maple: variation with vertical canopy strata and tree ontogenyECOLOGICAL ENTOMOLOGY, Issue 1 2010SEAN C. THOMAS 1. Although leaf morphology and chemistry show profound changes as trees age, the consequences of such changes to herbivory have received little attention, particularly late in the ontogeny of canopy trees. 2. Using a mobile aerial lift for canopy access, patterns of leaf damage were evaluated in canopy-dominant mature sugar maple (Acer saccharum Marsh) trees ranging from ,20 to 70 cm in diameter, corresponding to an age range of ,40,180 years. 3. Herbivore damage patterns varied in relation to both vertical canopy position (among upper-, mid-, and lower-canopy positions) and with tree size. Damage types attributable to herbivores active on leaf surfaces, including leaf skeletonizers and leaf cutters (both principally Lepidoptera), and leaf stippling inducers (Hemiptera) showed decreases with tree size, and with increasing height in the canopy. In contrast, leaf damage from the most abundant gall-forming arthropod in the system, the eriophyid mite Vasates aceriscrumena, increased markedly with tree size. 4. The results indicate that herbivory patterns vary with both canopy stratum and with tree size in sugar maple, and that the relative strength of vertical stratification and tree ontogeny effects are similar in magnitude. The predominant patterns are of a decrease in herbivory with increasing height in the canopy and with tree size, but certain galling arthropods exhibit the reverse trends. [source] Below-ground competition between trees and grasses may overwhelm the facilitative effects of hydraulic liftECOLOGY LETTERS, Issue 8 2004F. Ludwig Abstract Under large East African Acacia trees, which were known to show hydraulic lift, we experimentally tested whether tree roots facilitate grass production or compete with grasses for below-ground resources. Prevention of tree,grass interactions through root trenching led to increased soil water content indicating that trees took up more water from the topsoil than they exuded via hydraulic lift. Biomass was higher in trenched plots compared to controls probably because of reduced competition for water. Stable isotope analyses of plant and source water showed that grasses which competed with trees used a greater proportion of deep water compared with grasses in trenched plots. Grasses therefore used hydraulically lifted water provided by trees, or took up deep soil water directly by growing deeper roots when competition with trees occurred. We conclude that any facilitative effect of hydraulic lift for neighbouring species may easily be overwhelmed by water competition in (semi-) arid regions. [source] Fundamental characteristics and 3D electromagnetic analysis for magnetic levitation transporter using YBCO superconductorsELECTRICAL ENGINEERING IN JAPAN, Issue 2 2007Hiroshi Ueda Abstract A magnetic levitation device with two-dimensional movement, the so-called "levitating X-Y transporter," has been developed. In order to develop a working levitating X-Y transporter, it is necessary to clarify the levitation characteristics, such as the lift force, levitation height, and stability against mechanical disturbances. In this paper, we examine the lift and the restoring force experimentally and propose a new simulation program based on the three-dimensional hybrid finite and boundary element method to analyze the dynamic behavior of electromagnetic characteristics of YBCO bulk. Using the numerical simulation and experiments, we investigated a suitable arrangement of permanent magnets to enhance the levitation characteristics. We also designed a levitating transporter which can carry a load of 200 kg with a gap of 16 mm. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(2): 44,54, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20220 [source] Sensorimotor memory and grip force control: does grip force anticipate a self-produced weight change when drinking with a straw from a cup?EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2003Dennis A. Nowak Abstract We examined whether self-generated weight changes are anticipated by adequate grip force adjustments when repeatedly lifting an instrumented manipulandum. Subjects lifted a cup filled with 500 mL of water prior to and following drinking two portions of water with a straw without touching it. One half of the subjects drank from and lifted an uncovered cup receiving constant visual information about its filling level and the other half of the subjects drank from a covered cup without such visual feedback. During the lifts immediately following the drinking procedures, grip force scaling was erroneously programmed for the heavier weight of the preceding lift as was obvious from an inadequately high rate of grip force development. Vision had only a minor influence on the rate of grip force increase. The influence of vision on the scaling of peak grip force was more pronounced. More accurate force scaling was obtained with an increasing number of lifts performed under each weight condition, indicating an ongoing force adjustment process probably based on sensory feedback. We conclude that self-generation of a change in the weight of an object to be lifted is not, in itself, sufficient to elicit a predictive grip force output. Rather, accurate feedback information associated with the self-generated weight change is essential to update internal models related to the mechanical object properties. This assumption was confirmed in pilot experiments; when subjects lifted the cup after having poured water from it, they accurately scaled their fingertip force to the self-produced weight change. Here, direct sensory feedback from the grasping fingers could signal the weight change and update internal models while pouring water from the cup. Our data support the hypothesis that the sensorimotor system planning and processing predictive fingertip force can operate independently of higher-level cognitive and perceptual systems. [source] Hydraulic lift in a neotropical savannaFUNCTIONAL ECOLOGY, Issue 5 2003M. Z. Moreira Summary 1We report hydraulic lift in the savanna vegetation of central Brazil (Cerrado). Both heat-pulse measurements and isotopic (deuterium) labelling were used to determine whether hydraulic lift occurred in two common species, and whether neighbouring small shrubs and trees were utilizing this water. 2Both techniques showed water uptake by tap-roots and reverse flow of water in lateral roots. Roots transferred hydraulically lifted water to the soil, and small shrubs and trees neighbouring the labelled individuals were labelled by deuterated water. 3Isotopic mass-balance equations and sap-flow measurements showed that water taken up by the central tap-root in each individual constituted only a small percentage of total flux of water through the treated plants. Mass-balance equations also indicated that small shrubs and trees neighbouring the treated plants utilized only a few thousandths of a per cent of the label. 4The small proportion of water uptake by the tap-root of these two species may be limiting hydraulic lift in this system, unless sinker roots descending from lateral roots contribute to hydraulic lift. [source] Assembly rules and functional groups at global biogeographical scalesFUNCTIONAL ECOLOGY, Issue 5 2002D. R. Bellwood Summary 1The taxonomic and functional composition of reef fish assemblages are quantified in three biogeographical regions: Great Barrier Reef, French Polynesia and Caribbean. Assemblages are described in three habitats of differing wave exposure. Functional abilities are estimated based on published analyses linking fin morphology and swimming performance. 2Two questions were addressed: (1) To what extent are labrid assemblages similar among habitats and regions? (2) To what extent are functional characteristics of fish assemblages shaped by differences in biodiversity, evolutionary history and species composition? 3All three regions display highly congruent patterns of habitat use, in terms of assemblage structure and functional characteristics, despite a five-fold difference in species richness, limited or no species overlap, and a 3·2-Myear history of isolation. Exposed reef crest assemblages were dominated by fishes with fins reflecting lift-based high-speed locomotion. In contrast to abundance-based patterns, species presence/absence data were uninformative. 4The relationship between swimming ability and habitat use reveals underlying assembly rules at a functional level, emphasizing the utility of functional attributes as a metric for comparing system-level properties in taxonomically distinct faunas. [source] Desert shrub water relations with respect to soil characteristics and plant functional typeFUNCTIONAL ECOLOGY, Issue 3 2002J. S. Sperry Summary 1.,Soil characteristics influence plant communities in part through water relations. Hypothetically, finer textured soils in arid climates should be associated with more negative plant and soil water potentials during drought, greater resistance of xylem to cavitation, and shallower root systems than coarse soils. 2.,These hypotheses were tested by comparing the water relations of Great Basin shrubs growing in sand versus loam soils. The eight study species (Chrysothamnus nauseosus, Chrysothamnus viscidiflorus, Chrysothamnus parryi, Tetradymia glabrata, Atriplex canescens, Atriplex confertifolia, Grayia spinosa and Sarcobatus vermiculatus) varied in typical rooting depth and vegetative phenology. 3.,Xylem pressures for a species were, on average, 1·1 MPa more negative in the loam versus the sand site, despite greater precipitation at the loam site. Root xylem at the loam site was, on average, 0·9 MPa more resistant to cavitation than at the sand site for the same species. There was a strong trend for shallower rooting depths at the loam versus the sand site. Within a species, roots were consistently more vulnerable to cavitation than stems, and experienced more cavitation during the growing season. 4.,Over most of the summer there was much more cavitation at the loam site than at the sand site. More than 80% loss of xylem conductivity (PLC) was estimated in shallow roots of three species at the loam site by the end of July, with two of the three showing extensive leaf drop and branch mortality. Transpiration rate was negatively correlated with PLC, with a tendency for lower gas-exchange rates in loam versus sand. 5.,At the sand site, cavitation resistance was negatively correlated with estimated rooting depth. Drought-deciduous species had the shallowest root systems and greatest resistance to cavitation. In contrast, two species with phreatophytic tendencies were summer-active and were the most vulnerable to cavitation. 6.,The cavitation resistance of roots determines the minimum water potential permitting hydraulic contact with soil. Differences in cavitation resistance of roots between desert species may contribute to differences in sensitivity of gas exchange to soil drought, ability to perform hydraulic lift, and response to late summer rain pulses. [source] Progressive fatigue effects on manual lifting factorsHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 5 2009Anthony D. Banks The purpose of this study was to evaluate the effect of progressive fatigue on factors that previously have been associated with increased risk of low back pain in various occupational settings, during a repetitive lifting task where a freestyle lifting technique was used. A laboratory experiment was conducted to evaluate electromyography amplitude, kinematic, and kinetic parameters of repetitive freestyle lifting during a 2-hour lifting period. Subjective fatigue rating increased over time, indicating that the participant "felt" increasingly fatigued as the experiment progressed. Static composite strength decreased an average of 20% from the beginning to the end of the experiment. Effect of lifting posture (semi-squat, semi-stoop, and stoop) was observed on peak trunk flexion angle, trunk flexion angle at initiation of the lift, and knee angle at initiation of the lift indicating that, in freestyle lifting, participants assume quantitatively different lifting techniques. A significant effect of the time,posture interaction was observed on the dynamic leg lift floor to knuckle height strength, indicating that dynamic strength may change over time depending on lifting posture selected. © 2009 Wiley Periodicals, Inc. [source] Ergonomics interventions for wafer-handling task in semiconductor manufacturing industryHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 3 2002Hsiu-Chen Chung This article presents the ergonomic interventions in a semiconductor manufacturing company, with a focus on evaluating the effect of pod (wafer container) type and carrying distance on participants' maximal acceptable weight of lift (MAWL), heart rate (HR), wrist posture, and perceived exertion rating. Sixteen field operators participated in this study. The results indicate using the new pod with power grip handles produced greater MAWL than the old pod with pinch grip handles. On the other hand, the new pod also induced greater radial deviations than the old type. Recommendation for improving pod handle design is provided. Further, the increased carrying distance caused a decrease in MAWL and an increase in HR. Thus, using cart for intrabay pod transfer and minimizing manual carrying is also recommended. © 2002 Wiley Periodicals, Inc. [source] Development of Tactile Responses in Human Preterm and Full-Term Infants From 30 to 40 Weeks Postconceptional AgeINFANCY, Issue 1 2002Isabel Fearon Maturation of tactile sensitivity prior to term was examined in 36 preterm and 13 full-term infants using a fixed-trial, habituation procedure. Each infant was presented with a series of 8 habituation (arm stroke), 2 novel (arm lift), and 2 recovery (arm stroke) stimulus trials while heart rate and body movements were recorded. Maturation was observed with a gradual increase in the magnitude of the stimulus-elicited cardiac acceleration and cardiac-movement coupling from 30 to 40 weeks postconceptional age. The majority of infants displayed habituation,an excitatory response (heart rate acceleration and body movement),to the initial presentation of a tactile stimulus, response decline with repeated stimulations, and renewed response to a novel stimulus. A substantial number of infants (40%) failed to respond initially to the tactile stimulus, increased responding over several stimulus presentations, and failed to discriminate the presentation of a novel stimulus. We speculate that these differences in response patterns observed over all ages represent individual difference in the perception of stimulus intensity. [source] Optimal airfoil shapes for low Reynolds number flowsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 4 2009D. N. Srinath Abstract Flow over NACA 0012 airfoil is studied at , = 4, and 12, for Re,500. It is seen that the flow is very sensitive to Re. A continuous adjoint based method is formulated and implemented for the design of airfoils at low Reynolds numbers. The airfoil shape is parametrized with a non-uniform rational B-splines (NURBS). Optimization studies are carried out using different objective functions namely: (1) minimize drag, (2) maximize lift, (3) maximize lift to drag ratio, (4) minimize drag and maximize lift and (5) minimize drag at constant lift. The effect of Reynolds number and definition of the objective function on the optimization process is investigated. Very interesting shapes are discovered at low Re. It is found that, for the range of Re studied, none of the objective functions considered show a clear preference with respect to the maximum lift that can be achieved. The five objective functions result in fairly diverse geometries. With the addition of an inverse constraint on the volume of the airfoil the range of optimal shapes, produced by different objective functions, is smaller. The non-monotonic behavior of the objective functions with respect to the design variables is demonstrated. The effect of the number of design parameters on the optimal shapes is studied. As expected, richer design space leads to geometries with better aerodynamic properties. This study demonstrates the need to consider several objective functions to achieve an optimal design when an algorithm that seeks local optima is used. Copyright © 2008 John Wiley & Sons, Ltd. [source] CFD analysis of an oscillating wing at various reduced frequenciesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 2 2009Farooq Umar Abstract The effect of various reduced frequencies has been examined for an oscillating aspect ratio 10 NACA 0015 wing. An unsteady, compressible three-dimensional (3D) Navier,Stokes code based on Beam and Warming algorithm with the Baldwin,Lomax turbulence model has been used. The code is validated for the study against published experimental data. The 3D unsteady flow field is simulated for reduced frequency values of 0.1, 0.2 and 0.3 for a fixed mean angle of attack position and fixed amplitude. The type of motion is sinusoidal harmonic. The force coefficients, pressure distributions and flow visualization show that at the given conditions the flow remains attached to the wing surface even at high angles of attack with no clear separation or typical light-to-deep category of dynamic stall. Increased magnitude of hysteresis and higher gradients are seen at higher reduced frequencies. The 3D effects are even found at midspan locations. In addition, the rate of decrease in lift near the wing tips compared with the wing root is not much like in the static cases. Copyright © 2008 John Wiley & Sons, Ltd. [source] CFD-based optimization of aerofoils using radial basis functions for domain element parameterization and mesh deformationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 8 2008A. M. Morris Abstract A novel domain element shape parameterization method is presented for computational fluid dynamics-based shape optimization. The method is to achieve two aims: (1) provide a generic ,wrap-around' optimization tool that is independent of both flow solver and grid generation package and (2) provide a method that allows high-fidelity aerodynamic optimization of two- and three-dimensional bodies with a low number of design variables. The parameterization technique uses radial basis functions to transfer domain element movements into deformations of the design surface and corresponding aerodynamic mesh, thus allowing total independence from the grid generation package (structured or unstructured). Independence from the flow solver (either inviscid, viscous, aeroelastic) is achieved by obtaining sensitivity information for an advanced gradient-based optimizer (feasible sequential quadratic programming) by finite-differences. Results are presented for two-dimensional aerofoil inverse design and drag optimization problems. Inverse design results demonstrate that a large proportion of the design space is feasible with a relatively low number of design variables using the domain element parameterization. Heavily constrained (in lift, volume, and moment) two-dimensional aerofoil drag optimization has shown that significant improvements over existing designs can be achieved using this method, through the use of various objective functions. Copyright © 2008 John Wiley & Sons, Ltd. [source] Internal wave computations using the ghost fluid method on unstructured gridsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2005Sangmook Shin Abstract Two-layer incompressible flows are analysed using the ghost fluid method on unstructured grids. Discontinuities in dynamic pressure along interfaces are captured in one cell without oscillations. Because of data reconstructions based on gradients, the ghost fluid method can be adopted without additional storages for the ghost nodes at the expense of modification in gradient calculations due to the discontinuity. The code is validated through comparisons with experimental and other numerical results. Good agreements are achieved for internal waves generated by a body moving at transcritical speeds including a case where upstream solitary internal waves propagate. The developed code is applied to analyse internal waves generated by a NACA0012 section moving near interfaces. Variations of the lift acting on the body and configurations of the interfaces are compared for various distances between the wing and the interface. The effects of the interface are compared with the effects of a solid wall. Copyright © 2004 John Wiley & Sons, Ltd. [source] Numerical simulation of the unsteady flow over an elliptic cylinder at different orientationsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 8 2001H. M. Badr Abstract A numerical method is developed for investigating the two-dimensional unsteady viscous flow over an inclined elliptic cylinder placed in a uniform stream of infinite extent. The direction of the free stream is normal to the cylinder axis and the flow field unsteadiness arises from two effects, the first is due to the flow field development following the start of the motion and the second is due to vortex shedding in the wake region. The time-dependent flow is governed by the full conservation equations of mass and momentum with no boundary layer approximations. The parameters involved are the cylinder axis ratio, Reynolds number and the angle of attack. The investigation covers a Reynolds number range up to 5000. The minor,major axis ratio of the elliptic cylinder ranges between 0.5 and 0.6, and the angle of attack ranges between 0° and 90°. A series truncation method based on Fourier series is used to reduce the governing Navier,Stokes equations to two coupled infinite sets of second-order differential equations. These equations are approximated by retaining only a finite number of terms and are then solved by approximating the derivatives using central differences. The results reveal an unusual phenomenon of negative lift occurring shortly after the start of motion. Various comparisons are made with previous theoretical and experimental results, including flow visualizations, to validate the solution methodology. Copyright © 2001 John Wiley & Sons, Ltd. [source] Energy and exergy analysis of a double absorption heat transformer operating with water/lithium bromideINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2009H. Martínez Abstract In the present study, the first and second law of thermodynamics have been used to analyze in detail the performance of a double absorption (lift) heat transformer operating with the water,lithium bromide mixture. A mathematical model was developed to estimate the coefficient of performance (COP), the exergy coefficient of performance (ECOP), the total exergy destruction in the system (,TD) and the exergy destruction (,D) in each one of the main components, as a function of the system temperatures, the efficiency of the economizer (EFEC), the gross temperature lift and flow ratio (FR). The results showed that the generator is the component with the highest irreversibilities or exergy destruction contributing to about 40% of the total exergy destruction in the whole system, reason why this component should be carefully designed and optimized. The results also showed that the COP and ECOP increase with increase in the generator, the evaporator and the absorber,evaporator temperatures and decrease with the absorber and condenser temperatures. Finally, it was observed that the COP and ECOP are very dependent of the FR and the economizer efficiency (EFEC) values. Also the optimum operating region of the analyzed system is shown in the present study. Copyright © 2009 John Wiley & Sons, Ltd. [source] Theoretical and experimental comparison of the performance of a single-stage heat transformer operating with water/lithium bromide and water/CarrolÔINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2002W. Rivera This paper compares under the same operating conditions, the theoretical and experimental performance of a single-stage heat transformer operating with the water/lithium bromide and the water/CarrolÔ mixtures, where CarrolÔ is a mixture of lithium bromide and ethylene glycol [(CH2OH)2] in the ratio 1:4.5 by weight patented by Carrier Corp. Flow ratios, gross temperature lifts, useful heat, and coefficients of performance are plotted for the heat transformer against temperatures and solution concentrations. Because the water/CarrolÔ mixture has higher solubility than water/lithium bromide and high experimental values were obtained for the gross temperature lift, it seems to be a better alternative mixture to be used in absorption heat transformers. Copyright © 2002 John Wiley & Sons, Ltd. [source] Solution of the Dial-a-Ride Problem with multi-dimensional capacity constraintsINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 3 2006K. I. Wong Abstract The Dial-a-Ride Problem (DARP) consists of planning routes and schedules for picking up and delivering users within user-specified time windows. Vehicles of a given fleet with limited capacity depart from and end at a common depot. The travel time of passengers cannot exceed a given multiple of the minimum ride time. Other constraints include vehicle capacity and vehicle route duration. In practice, scheduling is made more complicated by special user requirements and an inhomogeneous vehicle fleet. The transportation of elderly and handicapped people is an important example, as space for wheelchairs is limited and a lift is required. In this study, we present a modified insertion heuristic to solve the DARP with multi-dimensional capacity constraints, and the performance of the proposed algorithm is tested in simulation. We show that the proposed methodology is effective when compared with the classic algorithms. [source] Implants placed in combination with an internal sinus lift without graft material: an analysis of short-term failureJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 2 2009Olaf Gabbert Abstract Aim: Investigation of the short-term survival of implants placed in combination with an internal sinus lift (ISL) without graft material. Material and Methods: Thirty-six patients received 92 screw-shaped dental implants in combination with an ISL. No bone grafts or bone substitutes were used. Forty-four patients with 77 implants in the native posterior maxilla served as controls. X-rays taken after implant placement and 6 months later were evaluated for the presence of bone gain at the apical aspect of the implants. Kaplan,Meier survival curves and Cox regression analysis were used to estimate survival curves and to isolate risk factors for implant failures. Results: Within a mean observation period of 1.2 years (minimum 9 months; maximum 3.7 years), four failures were recorded in the experimental group and two in the controls. The probability of survival was above 94% for both groups. Six,nine months after surgery, bone gain was observed in 29 out of 92 implants. Comparison of the experimental group and controls revealed no effect of ISL and membrane perforation on the probability of survival. Conclusions: Promising short-term outcomes were observed for implants with ISL without graft material; for a substantial proportion of implants, apical bone gain was observed in the first 6,9 months. [source] A hydro-mechanical approach to the scaling of swimming performance in the sand flathead Platycephalus bassensis Cuvier: effects of changes in morphological features based on fish sizeJOURNAL OF FISH BIOLOGY, Issue 6 2007K. Yanase The swimming performance of Platycephalus bassensis at steady speed was assessed with an emphasis on hydrodynamics. The minimum swimming speed to maintain hydrostatic equilibrium for P. bassensis of 0·271 m total length (LT) was calculated to be 1·06 LT s,1. At this speed, the required lift to support the mass of the fish was equivalent to 6·6% of the fish mass; 82·7% of which was created by the body as a hydrofoil, and the rest of which was created by the pelvic fins as hydrofoils. The minimum swimming speed decreased with the LT of the fish and ranged from 1·15 LT s,1 for a fish of 0·209 m to 0·89 LT s,1 for a fish of 0·407 m. The forward movement per tail-beat cycle (i.e. stride length) was described with an equation including quantities of morphological and hydro-mechanical relevance. This equation explained that stride length was increased by the effect of turbulence characterized by the Reynolds number and demonstrated the morphological and hydro-mechanical functional design of the fish for maximizing thrust and minimizing drag. The larger span of the caudal fin and caudal tail-beat amplitude was associated with larger stride length, whereas greater frictional drag was associated with smaller stride length. [source] Allometric constraints on stability and maximum size in flying fishes: implications for their evolutionJOURNAL OF FISH BIOLOGY, Issue 2 2003J. Davenport Flying fish wing area and wing-loading both rise in strongly negative allometric fashion with increasing body length and mass. Evidence is presented to show that this occurs because: (1) the leading edge of the pectoral fin ,wing' is fixed at 24% of standard length ( LS) from the snout, (2) the wing length cannot exceed 76% of LS or the tips will interfere with propulsive tail beat and (3) increased mass demands faster flying and wings with better lift : drag ratios; this selects for tapered, higher aspect ratio wing shapes. A consequence of this situation is that larger flying fishes have centres of mass increasingly further behind the centre of wing pressure. Resultant longitudinal instability restricts the maximum size of the two-winged design and the pelvic fins of four-wingers act as a stabilizing tailplane. These data indicate that the accepted model of evolution of flight in flying fishes (by extension of ballistic leaps) is flawed; it is proposed that evolution of lift-supported surface taxiing in half-beaks with enlarged pectoral fins (enhanced by ground effect) was an essential preliminary; subsequent forward migration of the centre of mass to within the wing chord permitted effective gliding. [source] The role of the pectoral fins in body trim of sharksJOURNAL OF FISH BIOLOGY, Issue 5 2000F. E. Fish In a large aquarium the leopard shark Triakis semifasciata, sand tiger shark Odontaspis taurus, sandbar shark Carcharhinus plumbeus, and spiny dogfish Squalus acanthias cruised steadily at 0·1-0·7 body lengths s -1. Relative to the trajectory of the shark, the pectoral fins were maintained at a positive angle of ttack regardless of vertical direction. For level swimming the mean angle of attack for the pectoral fin was 11±1·7, 10·1±1·3°, 9·3±1·3°, and 15·0±0·0 for T. semifasciata, C. plumbeus, O. taurus, and S. acanthias, respectively. The long axis of the body was canted at an angle of attack for T. semifasciata and S. acanthias, but trim was maintained during level swimming for C. plumbeus and O. taurus. Hydrodynamic analysis of the body and fin design of T. semifasciata indicated that the pectoral fins could develop suffcient pitching moment to maintain depth and keep the body in trim. Demonstration of positive angles of attack support the hypothesis that lift is generated in the anterior body to counterbalance the lift produced by the heterocercal tail. [source] Living on the bottom: Kinematics of benthic station-holding in darter fishes (Percidae: Etheostomatinae)JOURNAL OF MORPHOLOGY, Issue 1 2010Rose L. Carlson Abstract Darters represent a substantial radiation of freshwater fishes that live in close association with the substrate in North American streams and rivers. A key feature of any darter species is therefore its ability to stay in place or to "hold station" in flowing water. Here, we quantify the station-holding performance of two morphologically divergent darter species, the fantail darter Etheostoma flabellare and the Missouri saddled darter Etheostoma tetrazonum. We also characterize the primary kinematic responses of the two species when holding station in flow speeds ranging from 4 to 56 cm s,1 in a flow tank on either plexiglas or small rock substrate. We then present a series of hypotheses about the potential hydrodynamic and functional consequences of the observed postural changes and the links among morphology, posture, and station-holding performance. On both substrates, E. tetrazonum was able to hold station at higher flow speeds than E. flabellare. On rocks, E. tetrazonum slipped at an average speed of 55.7 cm s,1 whereas E. flabellare slipped at 40.2 cm s,1. On plexiglas, E. tetrazonum slipped at an average speed of 24.7 cm s,1 whereas E. flabellare slipped at 23.1 cm s,1. We measured body and fin positions of the two species from individual frames of high-speed video while holding station on rocks and plexiglas. We found that on both substrates, the two species generally exhibited similar kinematic responses to increasing flow: the head was lowered and angled downward, the back became more arched, and the median and caudal fin rays contracted as water flow speed increased. The ventral halves of the pectoral fins were also expanded and the dorsal halves contracted. These changes in posture and fin position likely increase negative lift forces thereby increasing substrate contact forces and reducing the probability of downstream slip. J. Morphol., 2010. © 2009 Wiley-Liss, Inc. [source] Investigation of solid,gas reaction heat transformer system with the consideration of multistep reactionsAICHE JOURNAL, Issue 9 2008C. Wang Abstract The performance of solid,gas reaction heat transformer system using MnCl2 and CaCl2 was investigated with the consideration of multistep reactions between CaCl2 and NH3. The reactions between CaCl2 and NH3 could be CaCl2·2/4NH3 and CaCl2·4/8NH3. The simulated results were verified by the experimental data. From the analysis results, it was concluded that the two reactions between CaCl2 and NH3 existed simultaneously. The favored conditions for the simultaneous occurrence of multistep reactions were discussed. The main reaction in the system with the initial state of CaCl2·2NH3 and CaCl2·4NH3 were designated as the reaction of CaCl2·2/4NH3 and CaCl2·4/8NH3, respectively. It was concluded that high driving temperature TM, large relative gas volume, and large specific heat transfer area were the favored conditions for the simultaneous occurrence of multistep reactions in the systems both with the initial state of CaCl2·2NH3 and CaCl2·4NH3. High initial charging pressure P0 was favored for the system with the initial state of CaCl2·2NH3, while low P0 was favored for the system with the initial state of CaCl2·4NH3. The impacts of the simultaneous occurrence of multistep reactions on the system performance indicators [temperature lift, specific power, and system coefficient of performance (COP)] were also investigated in this article. It was concluded that the occurrence of the reaction of CaCl2·4/8NH3 for the initial state of CaCl2·2NH3 led to better system performance, i.e., larger temperature lift, larger specific power, and larger system COP. However, the occurrence of the reaction of CaCl2·2/4NH3 for the initial state of CaCl2·4NH3 would lead to lower specific power. The temperature lift and system COP were larger for the initial state of CaCl2·4NH3; while the cycle period was shorter for the initial state of CaCl2·2NH3. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source] | |||||||||||||||||||||||||||||||||||||||||||