bluuebunny/crossref_metadata_2025 huggingface dataset:
Finding the right balance – a personal journey from individual proteins to membrane‐embedded motors
Authors: Robinson Carol V.
Published: December 2011

It is now more than 20 years since the prophetic words of John Fenn, announcing his discovery, stated that ‘Electrospray spectra have been obtained for biopolymers including oligonucleotides and proteins, the latter having molecular weights up to 130 000, with as yet no evidence of an upper limit’ (Fenn JB, Mann M, Kai Meng C, Fu Wong S & Whitehouse CM (1989) Science246, 64–71). Today, with the mass spectra of intact ribosomes at 2.3 MDa becoming almost routine and the first electrospray spectra of membrane‐embedded motors being recorded recently, new challenges are emerging. Knowledge of the intact mass of a protein or complex is only part of the MS information available. Data from the disruption of protein complexes in solution and gas phases are leading to subunit interaction maps and architectural models. Such models are enhanced by coupling with ion mobility in which the collision cross‐section of a protein complex can be defined. Linking these attributes with knowledge of subunit dynamics and the role of post‐translational modifications on the stability and interactions within complexes is increasing our understanding of the factors that stabilize and convert protein complexes between different quaternary states. From our earliest experiments, studying the folding of individual proteins, through to the characterization of membrane‐embedded motors, it is clear that the full potential of electrospray in structural biology has yet to be realized. The present review offers a personal view of the transition from determining the mass of an individual protein to elucidating the structure and dynamics of heterogeneous assemblies in the megadalton mass range.
Effect of enamel matrix derivative protein on the healing of standardized epithelial wounds: a histomorphometric analysis in vivo
Authors: Al‐Hezaimi Khalid , Al‐Askar Mansour , Al‐Fahad Hamad , Al‐Rasheed Abdulaziz , Al‐Sourani Nabil , Griffin Terrence , O’Neill Rory , Javed Fawad
Published: December 2011

The enamel matrix derivative (EMD) is a preparation of the enamel matrix proteins secreted by the Hertwig's epithelial root sheath. It has been shown that EMD promotes periodontal wound healing; however, the significance of the protein in repairing skin wounds is insufficiently addressed. The aim of this in vivo histomorphometric investigation was to analyse the effect of EMD protein on the healing of standardised epithelial wounds. Dorsal skin of 22‐week‐old female guinea pigs (n = 33) was scarified and divided into test‐ (topical application of EMD) and control‐sites (sutured and allowed to heal). Animals were euthanised at specific time intervals and the specimens were then evaluated histomorphometrically. The mean widths of the external wound gaps (WGs) in the test‐ and control‐sites at the 5th, 20th and 35th day of healing were 5·89, 3·6 and 1·01 mm and 6·41, 5·02 and 3·43 mm, respectively. Histomorphometric analysis showed a statistically significant difference in the WGs between the test‐ and control‐sites. A significant increase in the formation of organised connective tissue matrix, collagen fibres and early muscle formation was observed in the test‐sites as compared with the control‐sites. Within the limits of this study, it is concluded that topical application of the EMD on standardised epithelial allows early wound closure and promotes healing as compared to when the defects are merely sutured.
Assessment of the Analgesic Effect of Remifentanil using Three Pain Models in Healthy Korean Volunteers: A Randomized, Controlled Study
Authors: Kim Tae‐Eun , Kim Kyu‐Pyo , Shin Donghoon , Chung Yong‐Ju , Price Jeffrey , Mistry Prafull , Jang In‐Jin , Yu Kyung‐Sang
Published: December 2011

Quantitative pain assessment in human beings is useful for developing new analgesics. This study assessed the analgesic effect of remifentanil in 20 healthy Korean men using three pain models to investigate whether these models can be used in Asians. The study was a double‐blind, placebo‐controlled, two‐way cross‐over study. The subjects received intravenous remifentanil with doses starting at 0.01 μg/kg/min. and increasing by 0.01 μg/kg/min. up to 0.10 μg/kg/min. in one session; they received placebo in another session. Heat pain thresholds were assessed at dose levels of 0.02, 0.05, 0.08 and 0.10 μg/kg/min. Pressure pain threshold and tolerance and mechanical pain threshold were assessed at 0.08 μg/kg/min. Remifentanil dose‐dependently increased the heat pain threshold. The differences (95% confidence interval) between remifentanil and placebo were 1.54°C (0.78, 2.31), 1.82°C (1.11, 2.54) and 2.47°C (1.55, 3.38) at 0.05, 0.08 and 0.10 μg/kg/min. remifentanil, respectively. Remifentanil conferred a significantly higher pressure pain threshold and tolerance than placebo (p = 0.0001). There was a trend of increasing mechanical pain threshold with remifentanil, although it was not statistically significant. The results suggest that heat pain and pressure pain models are valid in East Asians for assessing analgesic effects.
‘That Tiny, Stratospheric Apex That Owns Most of the World’– Exploring Geographies of the Super‐Rich
Authors: HAY IAIN , MULLER SAMANTHA
Published: December 2011

This paper exhorts geographers to give critical attention to the super‐rich, defined as individuals with investable assets in excess of $1 million. The super‐rich currently number almost 11 million globally (2011) and have collective wealth in excess of $42 trillion. We argue that as a result of our discipline's typical, and not unjustifiable, focus on the poor and middle class, and our neglect of the super‐rich, geographers may both be overlooking potentially valuable insights to the institutions, practices, and cultural values of our society and gaining only a partial view of global capitalism. We point to prospectively useful work in areas that embrace relationships between the super‐rich, place, and mobility; links between wealth and (geo)politics; new philanthropy; and the social and environmental consequences of ‘luxury fever’. We also speculate as to some of the reasons for geographers’ apparent reluctance to engage with the super‐rich, responding to some of the critical methodological challenges associated with such work.
The Evolution of Private Equity in Emerging Markets: The Case of Poland
Authors: Klonowski Darek
Published: December 2011

In the last ten years, there has been a pronounced shift toward emerging markets in institutional investor allocations of capital to private equity. While the lion's share of the allocations to emerging markets have gone to the “BRIC” nations, lesser‐known markets like Poland are threatening to steal the spotlight. Economic stabilization, development of the private sector, a favorable business outlook, and continuous improvement of the local institutional infrastructure (laws, accounting rules, and fiscal regimes) have all contributed to the development of a vibrant private equity industry in Poland.

Most private equity firms in Poland structure their deals around five broad investment themes: technology; media; and telecommunications; manufacturing; consumer services; business services; and financial services. Local private equity firms have traditionally adopted two different strategies towards these sectors. The first group of private equity firms initially targeted manufacturing, with the conviction that, as the Polish economy developed, the satisfaction of consumer needs for basic products would be the largest source of market demand. The second group assumed that the market would require access to more services to accommodate the growing local economy. Both approaches have proved reasonably successful, as the leaders among these two groups of firms have continued to succeed in raising new funds while achieving high returns for their limited partners. And while the accomplishments of the private equity industry have been made possible by the extent of Poland's transformation from a socialist into a market economy, the industry itself continues to play an important role in this transformation by providing both outside capital and know‐how for local firms and managers.
Social Network Analysis and the Diffusion of the Strict Liability Rule for Manufacturing Defects, 1963–87
Authors: Bird Robert C. , Smythe Donald J.
Published: December 2011

This article reports the results of a study that uses social network analysis to compare the persuasiveness of legal precedents in the diffusion of the strict liability rule for manufacturing defects. This new study tests which legal precedents were most influential and also whether certain state judicial variables influenced the diffusion process. The results are striking. The federal circuit regions appear to define an important reference group in the diffusion process, and social network effects dominate economic and political variables. In addition, the de facto separation of powers in the enactment of new state legislation appears to influence courts' propensities to adopt the strict liability rule. When the executive and legislative branches were controlled by the same political party, regardless of whether it was Republican or Democratic, state courts were more inclined to adopt the strict liability rule.
Charities and the Big Society: a doomed coalition?
Authors: Morris Debra
Published: December 2011

While there is a central assumption that charities can be key implementers of Big Society ideals, this paper will consider whether there is compatibility between the political rhetoric of the Big Society and its delivery through the charitable sector. It will be maintained that, while much obvious synergy exists, there are inherent difficulties, at both the practical and theoretical level, for the large-scale involvement of charities and their volunteers in the delivery of the Big Society. At the practical level, it will be seen that some amendments to the legal framework, so as to accommodate the greater use of charities and volunteers within the Big Society, may need to be brought into effect. However, at the foundational level, an examination of the core characteristics of charities and their substantive legal principles reveals some more fundamental impediments to their fulfilling Big Society objectives laid out for them by government.
Two new records of the Tribe Phaeogenini Förster (Hymenoptera: Ichneumonidae: Ichneumoninae) from Korea
Authors: KWON Jin‐Man , JEONG Jong‐Chul , CHA Jin‐Yeol , LEE Jong‐Wook
Published: December 2011

We report two species that are new to Korea, Misetus borealis Kusigemati and Phaeogenes sapporensis Uchida. A key to Korean species of Phaeogenini, redescriptions and photographs of diagnostic characters are provided.
Reproduction of Female Lower Urinary Tract Symptoms on Urodynamics
Authors: COLHOUN Andrew , GOUDELOCKE Colin , ROVNER Eric S.
Published: December 2011

Objectives: Urodynamic testing (UDS) can be a valuable tool in the assessment of urinary incontinence and voiding dysfunction. The success of UDS in reproducing patients' symptoms has not been well defined. We sought to determine the ability of UDS to reliably reproduce various lower urinary tract symptoms and secondarily the ability of UDS to produce disparate findings not associated with patients presenting symptoms.

Methods: Following Institutional Review Board approval, patient data was accumulated prospectively over 10 months. Notation was made of primary and secondary symptoms as well as if these stated symptoms were reproduced during the urodynamic procedure. Presenting lower urinary tract symptoms included for analysis were stress, mixed and urge incontinence, urgency, and obstructive symptoms. We also reviewed the number of disparate urodynamic observations that did not correlate with patient history.

Results: Over a 10‐month period, 127 women had interpretable data with respect to whether their presenting symptoms were reproduced during UDS. Presenting symptoms were successfully reproduced on 83% of UDS studies. Disparate urodynamic observations were noted in 60% of patients.

Conclusions: Reproduction of patient symptoms during UDS occurred in the majority of cases if the patient was queried regarding this association. Additional disparate urodynamic observations were also noted in a majority of patients undergoing UDS. It remains unclear whether reproduction of symptoms during UDS in females ultimately results in improved interventional outcomes. The implications of new or unexpected UDS findings during UDS are unknown.
Size at birth and adult fat mass in twin sheep are determined in early gestation
Authors: Hancock S. N. , Oliver M. H. , McLean C. , Jaquiery A. L. , Bloomfield F. H.
Published: December 2011

Key points 

Reduced size at birth and shorter gestation length are both associated with increased risks of non‐communicable diseases (NCD) in later adult life.

Twins are born both smaller and earlier than singletons and adult twins also are reported to be at increased risk of common NCDs such as diabetes.

The smaller size and shorter gestation length of twins has been presumed to be due to a lack of intrauterine space and/or limitations of placental nutrient supply in late gestation, but there are few data to support this.

We show that size at birth and adult fat mass in twin sheep are determined largely in early gestation.

Knowledge of the mechanisms underlying early pregnancy determination of fetal growth and gestation length in twins are likely to increase understanding of how early pregnancy factors influence lifelong health for offspring from all pregnancies.
Solar Array Performance as a Function of Orbital Parameters and Spacecraft Attitude
Authors: Hough W. W. , Elrod B. D.
Published: December 2011

The dependence of solar array energy on orbital parameters is given for cases that achieve optimum array pointing, and therefore, maximum performance. Optimum pointing requires continual array articulation and/or active spacecraft attitude control. Performance obtained in local-vertical attitudes with fixed or incrementally articulated arrays is compared with the maximum.
A Theoretical and Experimental Investigation of the Dynamic Response of Rolamite
Authors: Percival C. M. , Norwood F. R.
Published: December 2011

In the following paper, Lagrange’s equation is used to derive an equation of motion for the rolamite mechanism in the ideal tight configuration; the effects of band inertia, force generation by bands of varying bending stiffness, and nonconservative forces are considered. An experimental system for investigating the dynamic response of rolamite is described. The effects of friction on the rolamite mechanism are discussed and experimentally determined values of coefficients of friction are presented.
Similarity in Gas-Borne Flowing Particulate Suspensions
Authors: Boothroyd R. G.
Published: December 2011

Examination is made of similar conditions concerning transport phenomena in the conveyance of particulate suspensions by gases. The paper, in large part, concerns conveyance in straight ducts. Pressure loss and heat transfer are considered together with the influence of electrostatic charging in fully developed flow. The case of suspensions of fine particles is considered from the point of view of a continuum. The different natures of flow both near and away from the duct wall are elucidated. The influence of agglomerative tendencies and particle/particle contact is also considered. The importance of the flow regime concept is illustrated for more involved situations where several factors contribute to overall transport phenomena.
Pneumatic Transport of Fine Granular Material
Authors: Broersma G.
Published: December 2011

Investigations show that production efficiency of foundries is influenced strongly by the nature and the use of means of transport. An important aspect of foundry transport is that of moulding sand. Impressive gains in space, as well as a decrease in capital investment may be had by applying pneumatic transport of moulding sand. The paper presents a basic approach to the nature of pneumatic transport of sand in a horizontal and circular tube, and indicates an approach to the calculation of the pressure gradient to be overcome. Although the analysis of the transport in a stationary laminar flow is interesting, it appears that sand is carried through a narrow sector of the tube, symmetrical to the vertical plane, and below the horizontal plane [1]. In the actual case of sand transport in a turbulent air current through a tube with a rough inner wall, sand is carried through the boundary layer at the complete circumference of the tube. It is easily seen how to generalize the approach for sand transport in a turbulent air current through a tube at an inclination to the horizontal, up to the vertical, and how to increase sand transport by injecting air which increases the turbulence of the boundary layer carrying the sand. After the various parameters for the stationary transport have been deduced, it appears to be possible to analyze the introduction of the sand grains into the air current as well as their acceleration to stationary motion [1].
Effect of Initial Pressures on Flowability of Bins
Authors: Johanson J. R.
Published: December 2011

The flow of bulk solids such as ore, coal, sugar and salt from storage bins depends on the pressures exerted by the bin walls on the solids. In the past the flow properties of bins have been determined on the basis of steady flow pressures. Recent experimental and theoretical work has shown that much larger pressures may be exerted on the solids during the initial filling of the bin. In this paper the effect of these initial pressures on the flow properties of bins is described and examples given for using the initial pressures to predict flow stoppages.
Adhesion and Agglomeration of Solids During Storage, Flow and Handling—A Survey
Authors: Pietsch W. B.
Published: December 2011

During storage, flow and handling of solids, particles in the micron range tend to adhere to walls or to each other. Such processes can cause severe disturbances and sometimes require the shut down of whole plants or costly reconditioning of caked products. Different binding mechanisms which can be classified into five groups and several undergroups can be responsible for adhesion and agglomeration. In Part 1 of the paper the occurrence and importance of the different possible binding mechanisms in respect to storage, flow and handling of solids is discussed and some equations for estimating binding forces are presented. Part 2 discusses the buildup of deposits in pneumatic conveying systems, the caking tendencies of fertilizers and methods for preventing severe adhesion or agglomeration in these special cases.
Failures of Reinforced Concrete Grain Silos
Authors: Theimer O. F.
Published: December 2011

In recent years many reinforced concrete grain silos have suffered serious damage either from inadequate foundations, or from incorrect reinforcement of bin walls, or from faulty structural work. The author discusses several instances of damaged grain silos and reasons for the failures, and gives methods of assuming correct bin loads and of designing reinforced concrete grain silos to prevent such failures.
Critical Pressure of Spherical Shell Acrylic Windows Under Short-Term Pressure Loading
Authors: Stachiw J. D.
Published: December 2011

Model and full scale acrylic windows in the form of spherical shell lenses with parallel convex and concave surfaces have been imploded by loading their convex surface hydro-statically at 650 psi/min rate while their concave surface was exposed to atmospheric pressure. The thickness of the model scale windows varied from 0.250 to 1.200 in. and of the full scale windows from 0.564 to 4.000 in., while the included spherical sector angle of the lens varied from 30 to 180 degrees in thirty degree increments. The low pressure face diameters of the model scale windows varied from 1.423 to 5.500 in., while those of the full scale windows varied from 6.200 to 35.868 in. In addition to critical pressures, displacement of the lens under hydrostatic pressure has been recorded and plotted as functions of pressure. The critical pressures of spherical acrylic windows have been found to be consistently higher than those of conical or flat disc acrylic windows of same thickness and low pressure face diameter subjected to short-term hydrostatic loading.
An Evaluation of ASME Ellipsoidal Heads
Authors: Gajewski R. R. , Lance R. H.
Published: December 2011

The ASME Code specifications for unfired cylindrical pressure vessels are examined from the viewpoint of the lower bound theorem of limit analysis. The problem is formulated as a linear programming problem and numerically solved using well-established algorithms on a digital computer. It is shown that lower bounds for collapse are less than the ASME Code specifications for such structures.
Cup Drawing from an Anisotropic Blank
Authors: Mir W. A. , Hillier M. J.
Published: December 2011

Tests on aluminum, copper and brass blanks indicate that, provided proper hold-down methods are used, the limiting drawing ratio that can be obtained is almost independent of type of blank holder. A comparison of theoretical and experimental critical punch loads at failure shows that, for aluminum, good agreement can be obtained when drawing under all-round hydrostatic pressure. This method produces a reduction in die friction and a significant increase in limiting drawing ratio. There is an optimum hydrostatic pressure above which no advantage is to be obtained.
Investigation of Face-Milling Tool Temperatures by Simulation Techniques
Authors: Wang K. K. , Tsao K. C. , Wu S. M.
Published: December 2011

This paper presents simulation techniques to further study the tool temperature distribution curve previously reported. The simulation setup employed a miniature oxyacetylene torch incorporated with a pulse control mechanism. The experimental simulation yielded similar temperature distribution curves to those obtained in the cutting experiments. The temperature distribution curve obtained by digital computer simulation shows a good agreement with that obtained in the cutting experiments. An analysis of the effect of the removed material near the tool tip was made using the numerical method. The result indicates that the material removed up to a tool tip thickness of 0.085 in., which was used in the previous paper, does not show significant effect on the temperature responses.
Wheel-Rail Adhesion
Authors: Marta H. A. , Mels K. D.
Published: December 2011

Wheel-rail adhesion has been the subject of vital interest to locomotive builders and the railroad. This area continued to receive considerable attention during the past decade due to the significant increase in horsepower available for traction of internally powered locomotives. For background information, this publication will briefly review the factors that affect adhesion and some of the published data on available adhesion between locomotive wheels and rail as a function of speed. Instrumentation, testing procedure, and results of adhesion tests on an SD-45 locmotive are discussed, and developed adhesion versus speed curves for different operating conditions are presented.
A New Criterion for Optimizing Linear Vibration Isolator Systems Subject to Random Input
Authors: Trikha A. K. , Karnopp D. C.
Published: December 2011

A new performance criterion is proposed for the synthesis of optimum linear isolators subject to random inputs. This criterion is based upon the values of displacement and acceleration; the probability of exceeding which, during the operational time, will be less than a desired value. A method is developed to solve this optimization problem for the case of stationary, Gaussian random input. Finally, systems optimized on the basis of the proposed criterion are compared with systems optimized according to the commonly used criterion which involves minimization of a weighted sum of the expected mean square values of displacement and acceleration.
Bending-Bending Mode of a Rotating Tapered-Twisted Turbomachine Blade Including Rotatory Inertia and Shear Deformation
Authors: Krupka R. M. , Baumanis A. M.
Published: December 2011

This paper presents the effect on natural frequency and mode shape of the inclusion of terms that are present in the general equations of motion to describe phenomena associated with Rotatory Inertia and Shear Deformation. The coupling that exists between the flexural and torsional vibrations is not considered. Carnegie’s formulation of the Lagrange Equations of motion is used and the set of field equations solved using Myklestad’s adaptation of the Holzer method. The definition of the lumped parameter system used and the derivation of the associated discrete “difference equations,” which are utilized in the computer approach to the boundary value problem considered, constitute an extension of the Carnegie work.
The Influence of Dissipative Heating on the Loss Factor of a Viscoelastically Damped Beam
Authors: Korites B. J. , Nelson F. C.
Published: December 2011

The influence of dissipative heating on the loss factor of a beam with a constrained viscoelastic layer is examined analytically and experimentally for the case in which the extensional stiffness of the constraining layer is large compared to the shear stiffness of the viscoelastic layer. It is shown that the loss factor may be substantially reduced by dissipative heating under these conditions.
A Spectrographic Sampling Method for Quick Assessment of Cylinder and Piston Ring Wear
Authors: Wisniowski H. U. , Jackson D. R.
Published: December 2011

A simple, inexpensive, and rapid method of assessing cylinder and piston ring wear was developed. A small sample of the oil which lubricates the cylinder wall and piston rings was drawn off through a small hole in the cylinder wall. The sample was then analyzed spectrographically. Changes in wear resulting from changes in cylinder liner materials, fuels, lubricating oils, and other operating conditions were investigated. The method was found useful especially in cases of drastic differences in the wear rates. Selected examples of these studies are reported.
Application of the Positive Thermoelastic Coefficients of Nickel-Iron Alloys to Wide-Temperature-Range Belleville Springs
Authors: Kessel P. G.
Published: December 2011

A method for producing a spring of constant spring-rate versus temperature up to the range of 1000 deg F is presented by series stacking of Belleville spring washers. Several different materials possessing the correct combinations of positive and negative thermoelastic coefficients may be utilized. Materials investigated in this study are types 304 and 430 stainless steels, and 31, 42, 49 Ni-balance Fe alloys. Experimental results for several material combinations are given along with the theoretical predicted results.
Torsion of Composite Elastic Bars of Arbitrary Cross Section
Authors: Sparrow E. M. , Yu H. S.
Published: December 2011

A method of analysis is presented for determining closed-form solutions for torsion of inhomogeneous prismatic bars of arbitrary cross section, the inhomogeneity stemming from the layering of materials of different elastic properties. It is demonstrated that the solution method is very easy to apply and provides results of high accuracy. As an application, solutions are obtained for the torsion of a bar of circular cross section consisting of two materials separated by a plane interface. The results are compared with those of various limiting cases and excellent agreement is found to exist. Among the limiting cases, an exact solution was derived by Green’s functions for the problem in which the interface between the materials coincides with a diameter of the circular cross section.
Computerized Determination and Analysis of Cost and Production Rates for Machining Operations. Part 1—Turning
Authors: Field M. , Zlatin N. , Williams R. , Kronenberg M.
Published: December 2011

Two of the most important factors in any machining operation are the cost per piece and the production rate. Equations have been developed which enable one to calculate these two factors for a given machining operation on a given part and machine tool. Generalized equations for cost and production rate are presented for turning, milling, drilling, reaming, and tapping. The items which make up the cost and production rate can be readily evaluated in each of the equations. The generalized cost per piece and production-rate equations for turning are then expanded to cover brazed and throwaway carbide tools and solid HSS tools. In order to use these equations, it is necessary to have available pertinent tool-life data for each of the tools under the actual machining conditions. Typical tool-life data have been generated and are shown here for a variety of alloys. All of the aforementioned equations have been programmed on a computer so that the cost and production rates can be readily calculated for specific parts, operations, and machine-tool combinations. The computer will print out not only the cost and production rate but also a detailed cost breakdown. A visual examination of each of the cost and production-rate factors makes possible a rapid analysis of the significance of each of the items making up the total cost and production rates. In addition, the cost and production-rate equations for turning have also been optimized. Thus calculations can be made to determine the minimum cost per piece and the maximum production rate for the cases where a mathematical expression, such as the Taylor equation, can be applied relating tool life and cutting speeds. Any projection beyond experimental data would have to be verified to serve as a guide for shop use.
Gear Couplings
Authors: Renzo P. C. , Kaufman S. , De Rocker D. E.
Published: December 2011

A discussion and mathematical analysis of the operation of gear couplings at angular misalignment; transmission of uniform motion, tooth separation, tooth load distribution, coupling load capacity, tooth bearing, and special tooth forms.
Liquid Rocket Engine Feed System Dynamics by the Method of Characteristics
Authors: Eschweiler J. C. , Wallace H. W.
Published: December 2011

A new approach was developed to predict pressure and flow transients in rocket engine feed systems. The one-dimensional equations of momentum and continuity were reduced by the method of characteristics from partial derivatives to a set of total derivatives describing state properties along specified paths. System components, e.g., valves and tanks, are represented by pseudo-steady state relations at discrete junctions in the system. Experiments were run on a typical attitude control feed system employing monomethylhydrazine (MMH) and nitrogen telroxide (NTO) as the propellant combination. The essential aspects of the analytical model mere verified by the excellent correlation achieved between the predicted and observed transjents.
Fatigue-Crack Growth-Rate Studies of Low-Alloy Pressure-Vessel Steels
Authors: Mowbray D. F. , Andrews W. R. , Brothers A. J.
Published: December 2011

Fatigue-crack growth rates were determined at room temperature for ASTM A302-Class B and A 508-Class 2 steels in two characteristic plate and forging directions. Tests were performed under zero-to-tension cyclic loading using both through-crack and part-through-crack plate specimens. Crack growth rates in the through-crack specimens, though affected by plate or forging directions, were found to correlate well upon the hypothesis that the crack extension per cycle is proportional to a positive power of the range of alternating stress intensity factor. In addition, the rate of crack extension through the plate thickness of the surface-crack specimens was successfully correlated with data from through-crack specimens.
Effect of Design Changes in Railway Catenary-Pantograph Systems on Power Collection at High Speed
Authors: Gray R. T. , Levy S. , Bain J. A. , Leclerc E. J.
Published: December 2011

Using a GE-635 computer program developed for the U.S. Department of Transportation, a study has been made of the effect of changes in the catenary-pantograph system on the quality of power collection at high speeds. The study explored the effect of: (a) Sag between towers, (b) pantograph spacing, (c) stiffness of the tower support, (d) damping and stiffness of the pantograph, (e) stiffness of the contact spring, (f) dropper stiffness, (g) dropper spacing. It was found that all of these have a significant effect on the constancy of the contact force between catenary and pantograph. By proper choice of system constants, the contact force variation can be substantially reduced. A basis is provided for selecting suitable system constants for a given range of operating conditions.
The Prediction of Pressure Loss During Two-Phase Horizontal Flow in Two-Inch Pipe
Authors: Andrews D. E. , Knowles C. R. , Eaton B. A. , Silberberg I. H. , Brown K. E.
Published: December 2011

This investigation of multiphase flow, supported jointly by the Texas Petroleum Research Committee, The University of Texas, and many companies affiliated with the oil industry, is an effort to develop a reliable method of predicting static pressure loss during two-phase horizontal flow in 2-in. pipe. The 165 two-phase tests were run in 1688 ft of 2-in. steel line pipe with water, distillate, and crude oil in connection with natural gas. The liquid flow rate ranged from 50 to 2500 B/D, with gas rates up to 6 MMscf/D. The range of mean line pressures was from 70 to 850 psig. Pressures were measured at 12 line locations, the liquid holdup was measured at two locations, and flow patterns were photographed through plastic pipe sections. From the data, correlations have been developed for liquid holdup and for an energy loss factor. The correlations can be used in conjunction with a derived equation to predict two-phase horizontal pressure losses. The prediction method is carefully outlined and, although it lends itself to computer usage, it is relatively fast and just as accurate by hand. Applied to the original data, the method yielded pressure gradients with an average error of 2.3 percent.
An Analytical Method of Synthesizing Mechanisms Based on Roulette Theory
Authors: Bussell W. H. , Martin G. H.
Published: December 2011

An analytical method of synthesizing four-bar mechanisms based on the motion of the coupler-bar plane is presented. The method is based on the theory of roulettes, which treats of the paths of points in the plane of a curve which rolls without slipping on another curve. The method is used to devise a mechanism having a coupler-bar curve which will approximate a desired curve. Also, the method is used to synthesize a mechanism which will approximate a given input-output crank angle relationship. It is best utilized with a digital computer.
Four Multiply Separated Positions in Coplanar Motion
Authors: Tesar D. , Eschenbach P. W.
Published: December 2011

The combination of infinitesimally and finitely separated positions in coplanar kinematics is investigated. Each combination requires a separate analytical treatment based on the fundamental concepts of Krause [1] and Bottema [2]. The combination considered in this paper is three infinitesimally separated and one finitely separated position. The result is a cubic curve having very similar properties to those already existing in the literature.
Beating in Three-Mass Systems Under Step Velocity Input. Part 2—Experimental
Authors: Stokey W. F. , Wunder R. A.
Published: December 2011

An experimental study of the response of three-mass systems to step changes of the base velocity is described. Recordings that show the beating that can occur between the vibrations in two normal modes of such systems are included. The excitation of these modes for various values of the system parameters is shown by calculated curves and by experimental results.
The Effect of Some Operating Variables in Vertical Spindle Abrasive Machining of Mild Steel
Authors: Pollock C.
Published: December 2011

This paper reports the results of a systematic test program designed to determine the effect of work area, downfeed rate, and segment grade on performance on vertical spindle surface grinders. Metal removal rate is shown to be a function of volumetric feed rate only. Wheel wear rate is shown to be a linear function of volumetric feed rate with the slope of each line a function of workpiece area. It is also shown that the effect of segment grade is to vertically displace the metal removal rate, wheel wear rate, grinding ratio, and power curves. The vertical displacement of the metal removal rate, wheel wear rate, and grinding ratio becomes progressively less as the hardness of the segment increases. The effect is reversed for power. The practical significance and application of this information are also discussed, showing examples of how it can be applied to solve certain general problems.
The Influence of Physical Properties on Penetration in Arc Welding
Authors: Caddell R. M.
Published: December 2011

Simple butt welds were produced using a particular metal and a variety of combinations of current, voltage, and welding velocity. Four metals possessing quite different physical properties were utilized. Coated stick electrodes and a d-c power source were employed and penetration was measured for each combination of work material and welding conditions. With the use of dimensional analysis, an expression was derived to predict penetration as a function of operating conditions and the physical properties of the metal welded. Within the range of variables investigated, the correlation between predicted values and measured values was quite reasonable.
Analysis of Oblique Cutting Forces
Authors: Henke Russell F.
Published: December 2011

This paper is the latest of a continuing series on the subject of self-excited machine tool chatter. The representation of the metal cutting process as required by the previously developed closed-loop chatter theory is extended to oblique cutting with tools of practical shape and geometry. The cutting process parameters essential to proper application of the stability theory are found by an analytical formulation leading to a classical eigenvalue problem. Techniques are developed to determine the steady-state constant of proportionality between resultant cutting force and uncut chip area, the direction of resultant cutting force, and the direction of maximum cutting stiffness for any single-point cutting operation. In the process, a general method to predict steady-state oblique cutting forces is evolved. The method depends on certain experimentally justifiable assumptions and utilizes previously compiled orthogonal cutting data.
Analysis of Plastic Flow Through Inclined Planes in Plane Strain
Authors: Avitzur B. , Fueyo J. , Thompson J.
Published: December 2011

A wide strip of thickness t0 is pulled or extruded through inclined planes converging with semiangle α and exit gap tf. While passing through the die, the thickness of the strip changes from t0 to tf, its length increases, but no change occurs in its width. A kinematically admissible velocity field is assumed to describe the flow. The expected distorted grid pattern is studied. Strain and strain rate fields are analyzed. Effective strain and effective strain rate distributions and their averages are defined. The same velocity field is utilized to obtain an upper-bound solution for the drawing and extrusion forces. Maximum reductions possible are predicted and the optimal included angle between the planes, required to minimize the forces, is evaluated. Formation and prevention of a dead zone are indicated. The analytical results are compared with other solutions and with published experimental data, where the independent variables are: Thicknesses t0 and tf, semiangle of the die α, friction (m), and flow stress of the material.
Measurements on Fully Wetted and Ventilated Ring Wing Hydrofoils
Authors: Acosta A. J. , Kiceniuk T. , Bate E. R.
Published: December 2011

Force measurements and visual observations were made in a water tunnel on fully wetted and ventilated flows past a family of conical ring wings having a flat plate section geometry. The diameter chord ratio was varied from one to three, at a fixed total included cone angle of 12 deg. The fully wetted flows all exhibited separation from the leading edge except for the largest diameter-chord ratio, a result which has been attributed to excessive cone angle. The effect of ventilation is to reduce markedly the lift curve slope. Pressure distribution measurements were also made under ventilating conditions for one member of this series. The effect of ventilation over only a portion of the circumference of the ring was also briefly investigated; large cross forces were developed by such ventilation.
Mechanics of the Abrasive Cutoff Operation
Authors: Shaw M. C. , Farmer D. A. , Nakayama K.
Published: December 2011

The abrasive cutoff operation in which a high-speed disk is fed radially into a steel member is analyzed. The feed rate and the wheel speed are the chief variables of importance. Cutting forces and wheel wear rate are analyzed in terms of chip size, grain spacing, and the length of work in the direction of cut. While the highest wheel speed possible should be used, there is an optimum feed rate. When the feed rate is low, an excessive wheel temperature is encountered, and wheel wear rate will be high. At a high feed rate, individual chips are too large for the space available, and wheel wear will also be high. Best performance from the point of view of wheel wear rate is obtained using a hard, dense wheel of large grain size (20 or coarser) operating at the highest wheel speed possible and with an intermediate feed rate.
Correlation of Maintenance Expense With Age of Plant and the Maintenance Penalty in Value Determination
Authors: Brennan J. F.
Published: December 2011

A statistical method is proposed for correlating maintenance expense with age of plant. The raw data are in dollars, taken from accounting record of yearly plant installations and maintenance expense. The age distribution of existing plant need not be known. By the use of the derived correlation equation, the maintenance penalty (value decrement caused by rising maintenance expense) is derived. The effect of inflation is also developed.
Deceleration of an Unbalanced Rotor Through a Critical Speed
Authors: Bodger W. K.
Published: December 2011

The problem of a single-degree-of-freedom rotor decelerating slowly through its critica speed is solved by an energy approach; a closed solution is obtained. A small discontinuous downward jump of rotor speed across the critical speed is shown to be required, either with or without damping in the system. The maximum increment of deflection, hence bending stress, in the rotor shaft is shown to be small, provided the rotor is carefully balanced and/or the system is sufficiently damped.
An Approximate Normal Mode Method for Damped Lumped Parameter Systems
Authors: Seireg A. , Howard L.
Published: December 2011

An approximate normal mode method is introduced which permits any linear non-conservative system to be solved by super position of uncoupled coordinates. Accuracy of the method was found to be good when checked by digital computer for dynamic damper systems subjected to sinusoidal and white noise random excitation. A technique is presented which permits a mathematical model for a damped multimass system to be constructed entirely from experimentally obtained sinusoidal frequency response data. An expression is derived for optimum damping ratio and natural frequency ratio that will minimize the response of a two-mass system to white noise random excitation.
An Investigation of an Impact Vibration Absorber
Authors: Egle D. M.
Published: December 2011

The impact vibration absorber consists of a small mass, moving unidirectionally, impacting against the ends of a container which is rigidly attached to the primary vibrating system. A simplified theory for the forced steady-state response of a linear, single-degree-of-freedom system with an impact vibration absorber is presented. The assumption of two impacts per cycle at equal time intervals is known to lead to two possible solutions near the resonant frequency of the primary system. A criterion for determining the stability of the solutions is developed. An approximate expression for the maximum displacement of the primary system is given and the theory is compared to experimental results.
Damping in Sandwich Beams With Shear-Flexible Cores
Authors: Bert C. W. , Wilkins D. J. , Crisman W. C.
Published: December 2011

This paper is a theoretical and experimental study of the effect of core shear flexibility on the lowest natural frequency, node locations, and damping in sandwich beams with cores of high shear flexibility as exemplified by honeycomb-type cores. A new method of analysis is presented for predicting the logarithmic decrement for damping in sandwich beams undergoing free vibration, provided that the beam geometry and constitutent material properties are known. Natural frequency, modal shape, and logarithmic decrement are all dependent upon the dynamic shear coefficient. Two new simplified derivations for this coefficient are presented in this paper. Flexural vibration experiments were conducted on free-free sandwich beam strips at frequencies from 300 to 700 cps. Facings were glass-epoxy laminates and cores were hexagonal-cell honeycomb of either aluminum or glass-phenolic. For each beam, lowest natural frequency, associated node locations, and logarithmic decrement in free vibration were measured and compared with those predicted by applying four different theories.
Vibratory Penetration of Soils
Authors: Senator M.
Published: December 2011

An approximate expression is found for the penetration rate of a flexible penetrator, modeled as two masses joined by an elastic member with damping, with applied bias and harmonic forces. Modified Coulomb friction is used to characterize soil resistance. The approximate theory is compared with analog computer measurements and with an exact theory (developed for the limiting case of zero front mass and internal damping) and is found to give good agreement in lite range of small excess harmonic force amplitude. A comparison with a rigid penetrator is also made, and the flexible penetrator is shown to have the important design advantage of smaller weight or smaller applied harmonic force for equal penetration rates.
Synthesis of Epicyclic Gear Trains Using the Velocity Ratio Spectrum
Authors: Brewer R. C.
Published: December 2011

For a simple epicyclic train, the controlling element is almost invariably fixed, i.e., prevented from rotating by being connected, in some way, to the frame. Such trains are easy to synthesize because there are a limited number of variations of the three basic elements and, normally, six equations will define all possible velocity ratios. For a compound epicyclic train, the number of equations is considerably increased. A method of synthesizing compound epicyclic trains is developed using the concept of a velocity ratio spectrum. To facilitate the application of this concept, only one train in a compound epicyclic train is regarded as basic; all others are considered as merely serving the purpose of modifying the motion of the controlling element in the basic train.
Rocket Motor Gear Tooth Analysis (Hertzian Contact Stresses and Times)
Authors: Gatcombe Ernest K. , Prowell Roy W.
Published: December 2011

In this paper a rocket motor turbine-pump reduction gear system is analyzed in regard to Hertzian gear tooth contact stresses and times of contact. It is found that the Hertzian contact stresses vary from approximately 100,000 psi to 200,000 psi. The times of contact vary from three to eight microsec. Some observations regarding the correlation between contact times and gear failures are made. It is indicated that it may be possible to establish design limitations on the contact times to insure satisfactory gear operation. Sample calculations for evaluating each of the typical quantities found in the tables are included.