bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comparison of Regenerative-Pump Theories Supported by New Performance Data
Authors: Senoo Yasutoshi 
Published: February 2022

Abstract
Several theories of the fluid-dynamic mechanism of a regenerative pump have been presented in the literature. The author has compared these theories and believes that in principle they are compatible. The differences occur in the assumptions made. Experimental data show that, although each assumption is useful for a limited operating condition and geometry, none covers a wide enough range for a complete analysis of the phenomenon. In addition, he presents a series of experimental data concerning the geometry of the pumping channel. Although the influence of the geometry of the pumping channel on performance is complicated, consistent tendencies are found. These tendencies and experimental data are available not only as an aid to design but also may serve as a guide for the improvement of any simple semiempirical theory of the regenerative pump as well as for testing any complete theories.
On the Tool-Life and Temperature Relationship in Metal Cutting
Authors: Ling F. F. , Saibel Edward 
Published: February 2022

Abstract
The empirical relationship of Schallbroch, Schaumann, and Wallichs (1) between tool life and cutting temperature is examined in the light of recent developments in rupture theory. Cutting-tool failure is viewed essentially as a rupture process and the data relating tool life and cutting temperature are interpreted from a reaction-rate theory point of view. The significance of cutting temperature is examined critically and its limitations are pointed out.
Analysis of the Stresses in a Cutting Edge
Authors: Archibald F. R. 
Published: February 2022

Abstract
This paper is concerned with stresses in metal cutting in the tool itself. These stresses are within the elastic region and can therefore be treated by the methods of the theory of elasticity. The tool is considered as a wedge having normal and tangential loading on one face. Equations for the stress components at any point of the tool tip are obtained. Particular attention is given to the edge of the tool where stresses of several hundred thousand pounds per square inch are found. The calculations offer a basis for the rational design of cutting tools and they also should be of value in metal-cutting research on tool failure.
Engineering Relations for Heat Transfer and Friction in High-Velocity Laminar and Turbulent Boundary-Layer Flow Over Surfaces With Constant Pressure and Temperature
Authors: Eckert E. R. G. 
Published: February 2022

Abstract
Relations are presented which permit a rapid calculation of friction and heat transfer from two-dimensional high-velocity flow to surfaces with locally constant pressure and temperature and with laminar and turbulent boundary layers. The calculation procedure is one which has been well established in the field of heat transfer, namely, to use equations for friction and heat-transfer parameters which have been developed for constant-property fluids and to adapt them to conditions where properties vary in such a way that those properties are introduced into the equations at a properly determined reference temperature. Relations are developed for this reference temperature which make the results of the outlined method agree best with published laminar boundary-layer solutions. The same relations turn out to give also good representation of measured results on turbulent boundary layers. The following advantages are connected with this particular method. It gives answers by simple calculations and it is quite generally applicable. The friction and heat-transfer equations are valid for any fluid gas or liquid. The relation for the reference temperature (or enthalpy), gives very good agreement with boundary-layer solutions regardless of the specific variation of the property values on which the calculations had been based. Therefore it may be expected that they are not only valid for air at any pressure and temperature level (as long as slip flow and dissociation are avoided) but approximate real conditions well also for other gases.
Hydraulic Transients in Centrifugal Pump Systems
Authors: Kittredge C. P. 
Published: February 2022

Abstract
Differential equations of motion for (a) the rotating parts of the pump and prime mover, and (b) the fluid in the pipes are derived. Methods of integrating the equations are discussed for the case of an assumed rigid fluid column and for the elastic fluid column. A hitherto unpublished solution for the elastic-column problem is described. Complete characteristics diagrams for several pumps are given. Solutions by different methods are compared and examples for actual installations shown.
Thermal Lags in Flowing Incompressible Fluid Systems Containing Heat Capacitors
Authors: Rizika J. W. 
Published: February 2022

Abstract
The transient thermal conditions in problems involving flowing fluid systems in contact with heat capacitors are becoming increasingly important with the advent of modern control techniques. The temperature controlability of a flowing fluid system is a direct function of the transient thermal response of the fluid to a specific temperature input function. In a previous paper, the author presented an analysis which considered the transient fluid temperatures in a system consisting of a compressible fluid flowing through a duct or in a heat exchanger. The case of a compressible fluid, with an exponential or step-function fluid temperature input, flowing through an insulated tube or pipe was analyzed in detail and examples were presented. The treatment of the transient conditions for a compressible fluid flowing through a heat exchanger was partially analyzed and the method of solution was demonstrated. The present paper consists of an extension of this work in which the transient conditions due to thermal lags in flowing incompressible fluid systems are analyzed. Both the case of an incompressible fluid, with a step-function temperature input, flowing through a circular tube or pipe and the case of an incompressible fluid flowing in a simple heat exchanger are examined in detail. An example which demonstrates the transient condition at the exit of a simple (condensing-steam/water) heat exchanger is presented also.
A Systematic and Rapid Procedure of Computing Approximate Characteristic Values Pertaining to Bare-Tube Crossflow Heat Exchangers
Authors: Neugebauer F. J. 
Published: February 2022

Abstract
This paper presents a systematic method of determining approximate characteristic values pertaining to crossflow heat exchangers of the bare-tube bundle type. Only the case of turbulent flow has been taken into consideration. The method described allows rapid computation of entire families of heat exchangers having the same requirements with regard to heat-transfer and pressure losses. The basic idea of this method is not confined to the aforementioned type of heat exchanger and flow pattern. The interested reader will immediately recognize that the method can be adapted to other configurations.
Effect of Range of Stress in Combined Bending and Torsion Fatigue Tests of 25S-T6 Aluminum Alloy
Authors: Findley W. N. , Mitchell W. I. , Strohbeck D. D. 
Published: February 2022

Abstract
Fatigue-test data under bending, torsion, and combined bending and torsion are presented for mean stresses from zero to values which caused substantial yielding. The mean normal stresses in the bending and the torsion tests were corrected for the effect of the nonlinear distribution of stress resulting from yielding. The effect of stress relaxation at high mean stresses was investigated. The applicability of several theories of failure are compared with these test data. The influence of anisotropy, mechanism of crack formation, mean stress, and maximum stress are discussed.
Effect of Vapor Velocity on Laminar and Turbulent-Film Condensation
Authors: Rohsenow W. M. , Webber J. H. , Ling A. T. 
Published: February 2022

Abstract
The liquid condensate layer (film) on vertical plates or tubes under the influence of the gravity force flows downward in essentially laminar flow over the upper part of the surface but may change to turbulent flow over the lower part if the condensation rate is sufficiently high. Colburn (1) reviewed the results of Kirkbride and developed a correlation equation based on a very elementary description of the condensate layer which was considered to be composed of a laminar sublayer and a turbulent outer region. The laminar layer was considered to have the sole resistance to heat transfer. This type of analysis was extended by Carpenter and Colburn (2, 3) to include the effect of vapor shear stress. Seban (4) performed an analysis of the turbulent condensate film assuming the existence of the “universal velocity distribution” of Prandtl-Nikuradse. The calculated results extend over a wide range of Prandtl numbers and agree well with the empirical results of Colburn (1) in the range NPr = 2 to 5. This paper presents analyses showing the effect on rates of condensation of vapor shear stress at the liquid-vapor interface. Both laminar and turbulent films are considered and are combined to give analytical results for the case of laminar flow on the upper portion of a plate and turbulent flow on the lower portion. The analysis of the turbulent film is essentially an extension of the one presented by Seban (4). The system considered is a vertical flat plate, Fig. 1, with pure saturated vapor condensing on the plate whose temperature is uniform. Flow acceleration and momentum changes are neglected in the analysis. The physical properties are assumed to be constant.
Frictional Characteristics and Surface Damage of Thirty-Nine Different Elemental Metals in Sliding Contact With Iron
Authors: Goodzeit C. L. , Hunnicutt R. P. , Roach A. E. 
Published: February 2022

Abstract
This paper describes an experimental investigation of the friction and surface-damage characteristics of iron in sliding contact with various elemental metals without lubrication. No simple, direct relationship was found between the value of the coefficient of sliding friction and the characteristics of the material transfer between metals. It was found that the surface-damage characteristics are related to the relative hardness of the metals in sliding contact, their mutual solubility, and their ability to form intermetallic compounds.
The Slotted-Blade Axial-Flow Blower
Authors: Sheets H. E. 
Published: February 2022

Abstract
The slotted blade applies boundary-layer control to the blades of axial-flow blowers. This offers a means to design axial-flow blowers for higher efficiencies, or higher pressure coefficient, or possibly a combination of both. Test data of an experimental blower are presented, indicating blower efficiencies to 94 per cent and stage efficiencies to 96 per cent with high-pressure coefficients corresponding to a maximum flow deflection of about 52 deg.
Thermodynamic Aspects of Cavitation in Centrifugal Pumps
Authors: Stahl H. A. , Stepanoff A. J. 
Published: February 2022

Abstract
The effect of liquid properties on centrifugal-pump behavior under cavitation conditions is examined on the basis of a given pump handling various liquids. A criterion in terms of physical properties of the liquid is established which can be used to indicate cavitation effects on pump performance for various liquids. Test results and numerical illustrations are presented.
The Design of Axial Flow Pumps
Authors: Bowerman R. D. 
Published: February 2022

Abstract
A design procedure for axial-flow pump impellers is presented that accounts for induced interference effects in the prediction of performance. Induced interference velocities at an impeller blade have been calculated using a three-dimensional model that includes the effects of the other blades and of the total downstream vorticity along the center line of the pump. The design method considers improvement of cavitation conditions by specifying the radial variation of the design parameters such that the pressure distributions on all radial sections are similar. An analysis of optimizing the impeller geometric parameters for cavitation conditions is presented to permit the initial choices of the quantities appearing in the design procedure. Experimental work on a two-bladed impeller has yielded results that give good support to all aspects of the design method.
Suppression of Pump Vibrations Set Up at Starting Up—Preopening Method
Authors: Numachi F. 
Published: February 2022

Abstract
Cases occur in large water pumps, wherein, after installation, vibrations exceeding allowable limits are found to set in when starting up, and as a measure to meet such situations without resorting to reconstruction of the pump itself, a method of “preopening” is presented in this paper, which consists of opening up the delivery valves to a certain extent while the pump is gradually being worked up to full speed. The method of estimating the quantity of reverse flow, the torque required, and the time necessary for attainment of normal speed is explained. An example of application in actual practice is further given.
The Thermodynamics of Cooled Turbines: Part 2—The Multistage Turbine
Authors: Hawthorne W. R. 
Published: February 2022

Abstract
The reheat factor and the turbine efficiency can be calculated from the stage efficiency for an uncooled turbine and for one in which the blades are cooled. A chart has been prepared for rapid computations and the results are compared with those obtained from stage-by-stage calculations, showing good agreement.
Laminar-Free-Convection Heat Transfer From the Outer Surface of a Vertical Circular Cylinder
Authors: Sparrow E. M. , Gregg J. L. 
Published: February 2022

Abstract
A solution of the laminar boundary-layer equations has been obtained for free convection from the outer surface of a vertical cylinder. The temperature of the cylinder surface was taken to be uniform. Heat-transfer results have been found for Prandtl numbers of 0.72 and 1 (i.e., for gases) and are presented on graphs. The Nusselt numbers for the cylinder were higher than those for the flat plate. Also, the deviation of the cylinder Nusselt numbers from those for the flat plate was greater for Prandtl number of 0.72 than for Prandtl number of 1. A quantitative criterion was established for determining the conditions under which the heat transfer from a cylinder could be calculated with sufficient accuracy using the flat-plate results. An analysis based on replacing the free-convection problem by a problem in pure conduction through a fictitious layer of stagnant fluid gave good agreement with the boundary-layer solution.
An Improved Thermochemical Energy Storage Material Using Nanocellulose to Stabilize Calcium Chloride Salt
Authors: Gladen Adam C. , Bajwa Dilpreet 
Published: February 2022

Abstract
One promising thermochemical reaction for energy storage is the hydration of hygroscopic salts. However, pure salts have poor cycle stability. The present work investigates a new composite material by impregnating a framework of crystalline nanocellulose (CNC) with calcium chloride (CaCl2). A key aspect of this material is the potential for a nanoscale, stabilizing framework provided by the CNC. Various weight ratios of CNC:CaCl2 were synthesized. The attachment of the salt to the CNC was determined by TEM and FTIR analyses. The weight loss and enthalpy of dehydration were measured after hydration at prescribed relative humidity and a fixed hydration time. The stability was determined by conducting multiple cycles. The results show that CNC can be successfully impregnated with salt. The nanocellulose binds to submicron salt particles and provides a stabilizing, nanoscale architecture. The composite material shows improved energy storage characteristics and stability. For the given hydration conditions, the CNC improves the hydration rates and allows more water to be absorbed within the hydration timeframe. This improved reaction rate can improve the enthalpy of dehydration for the fixed hydration time. Insufficient CNC (i.e., 1:10) allowed the salt particles to more easily deliquesce. With sufficient CNC framework, the CNC–salt material demonstrated improved stability by retaining structural integrity and specific enthalpy over the course of multiple cycles while pure CaCl2 deliquesced.
The Record Power Profile of Male Professional Cyclists: Normative Values Obtained From a Large Database
Authors: Valenzuela Pedro L. , Muriel Xabier , van Erp Teun , Mateo-March Manuel , Gandia-Soriano Alexis , Zabala Mikel , Lamberts Robert P. , Lucia Alejandro , Barranco-Gil David , Pallarés Jesús G. 
Published: February 2022

Purpose: To present normative data for the record power profile of male professional cyclists attending to team categories and riding typologies. Methods: Power output data registered from 4 professional teams during 8 years (N = 144 cyclists, 129,262 files, and 1062 total seasons [7 (5) per cyclist] corresponding to both training and competition sessions) were analyzed. Cyclists were categorized as ProTeam (n = 46) or WorldTour (n = 98) and as all-rounders (n = 65), time trialists (n = 11), climbers (n = 50), sprinters (n = 11), or general classification contenders (n = 7). The record power profile was computed as the highest maximum mean power (MMP) value attained for different durations (1 s to 240 min) in both relative (W·kg−1) and absolute units (W). Results: Significant differences between ProTeam and WorldTour were found for both relative (P = .002) and absolute MMP values (P = .006), with WT showing lower relative, but not absolute, MMP values at shorter durations (30–60 s). However, higher relative and absolute MMP values were recorded for very short- (1 s) and long-duration efforts (60 and 240 min for relative MMP values and ≥5 min for absolute ones). Differences were also found regarding cyclists’ typologies for both relative and absolute MMP values (P < .001 for both), with sprinters presenting the highest relative and absolute MMP values for short-duration efforts (5–30 s) and general classification contenders presenting the highest relative MMP values for longer efforts (1–240 min). Conclusions: The present results––obtained from the largest cohort of professional cyclists assessed to date—could be used to assess cyclists’ capabilities and indicate that the record power profile can differ between cyclists’ categories and typologies.
Extra-axial haemorrhages in young children with skull fractures: abuse or accident?
Authors: Wallace Jordan , Metz James Benson , Otjen Jeffrey , Perez Francisco A , Done Stephen , Brown Emily C B , Wiester Rebecca T , Boos Stephen C , Ganti Sheila , Feldman Kenneth W 
Published: February 2022

ObjectiveInfant and toddler subdural haemorrhages (SDH) are often considered indicative of abuse or major trauma. However, accidental impact events, such as falls, cause contact extra-axial haemorrhages (EAHs). The current study sought to determine frequency and clinical behaviour of EAHs with infant and toddler accidental and abusive skull fractures.Patients and methodsChildren aged <4 years with accidental skull fractures and abusive fractures identified by CT at two paediatric tertiary care centres. Clinical data were abstracted by child abuse paediatricians and images were reviewed by paediatric radiologists. Data were analysed using univariate and multivariate logistic regression as well as descriptive statistics.ResultsAmong 227 subjects, 86 (37.9%) had EAHs. EAH was present in 73 (34.8%) accidental and 13 (76.5%) of the abusive injuries. Intracranial haemorrhage rates were not different for children with major or minor accidents but were fewer than abused. EAH was equally common with falls <4 and>4 ft. EAH depths did not differ by mechanism, but 69% of accidental EAHs were localised solely at fracture sites vs 38% abuse. Widespread and multifocal EAHs were more common with abuse. Children with abuse or major accidental injuries presented with lower initial Glasgow Coma Scales than those with minor accidents. Abused children had initial loss of consciousness more often than those with either minor or major accidents.ConclusionsSimple contact EAHs were common among children with minor and major accidental skull fractures. Accidental EAHs were more localised with less neurological dysfunction than abusive.
Cost-effectiveness of full endoscopic versus open discectomy for sciatica
Authors: Gadjradj Pravesh Shankar , Broulikova Hana M , van Dongen Johanna M , Rubinstein Sidney M , Depauw Paul R , Vleggeert Carmen , Seiger Ankie , Peul Wilco C , van Susante Job L , van Tulder Maurits W , Harhangi Biswadjiet S 
Published: February 2022

ObjectiveTo assess the costs and cost-effectiveness of percutaneous transforaminal endoscopic discectomy (PTED) compared with open microdiscectomy among patients with sciatica.MethodsThis economic evaluation was conducted alongside a 12-month multicentre randomised controlled trial with a non-inferiority design, in which patients were randomised to PTED or open microdiscectomy. Patients were aged from 18 to 70 years and had at least 6 weeks of radiating leg pain caused by lumbar disc herniation. Effect measures included leg pain and quality-adjusted life years (QALYs), as derived using the EQ-5D-5L. Costs were measured from a societal perspective. Missing data were multiply imputed, bootstrapping was used to estimate statistical uncertainty, and various sensitivity analyses were conducted to determine the robustness.ResultsOf the 613 patients enrolled, 304 were randomised to PTED and 309 to open microdiscectomy. Statistically significant differences in leg pain and QALYs were found in favour of PTED at 12 months follow-up (leg pain: 6.9; 95% CI 1.3 to 12.6; QALYs: 0.040; 95% CI 0.007 to 0.074). Surgery costs were higher for PTED than for open microdiscectomy (ie, €4500/patient vs €4095/patient). All other disaggregate costs as well as total societal costs were lower for PTED than for open microdiscectomy. Cost-effectiveness acceptability curves indicated that the probability of PTED being less costly and more effective (ie, dominant) compared with open microdiscectomy was 99.4% for leg pain and 99.2% for QALYs.ConclusionsOur results suggest that PTED is more cost-effective from the societal perspective compared with open microdiscectomy for patients with sciatica.Trial registration numberNCT02602093.