bluuebunny/crossref_metadata_2025 huggingface dataset:
Applying Parameter‐Estimation Methods to Recovery‐Test and Slug‐Test Analyses
Authors: Mills Andrew C.
Published: November 2009

Parameter‐estimation methods, including an exhaustive‐search method and PEST (Parameter ESTimation) software, were applied to recovery‐test data and slug‐test data to obtain best estimates of transmissivity (T) by minimizing the sums of residuals. Each residual represents the difference between the field‐measured water‐level value and the value calculated by the appropriate non‐linear equation. The exhaustive‐search method in both cases involves computing the sums of residuals for an array of transmissivity and storativity values selected by the user for testing. Two new Fortran programs are presented that employ the exhaustive‐search method. They utilize Picking's method for analyzing recovery‐test data and the analytical equation for analyzing slug‐test data derived by Cooper, Bredehoeft, and Papadopulos. Picking's method involves application of the Papadopulos and Cooper's equation for drawdown in finite‐diameter wells. Utilizing field data reported in the literature, the estimated transmissivity values from the exhaustive‐search methods were compared to the literature values obtained by type‐curve matching techniques. The exhaustive‐search values corresponded closely to the curve‐matching values. Estimates for T were also obtained from recovery‐test and slug‐test data from two sites in southeastern Pennsylvania. For these sites, the PEST program was also applied to the data to evaluate the accuracy of the exhaustive‐search methods. The results from the two methods were generally in good agreement. The two new Fortran programs are practical tools for the hydrogeologist, as they require less time compared to type‐curve matching and the PEST method, and they yield accurate estimates of transmissivity.
The Excretion of Urate at Various Plasma Concentrations and During Osmotic Diuresis in the Rabbit
Authors: MøLLER JESPER V.
Published: November 2009

The secretory and reabsorptive processes for urate in the rabbit kidney have been studied in experiments in which the plasma urate concentration was varied. The curves relating net secretion of urate to the plasma concentration showed an initial dip below zero, indicating net reabsorption at low levels, and then rose linearly. At very iiigh plasma levels (2–4 μmioles/ml) an upper limit for net secretion of urate of 30–35 μmoles/min was demonstrated in 2 expts. Osmotic diuresis (induced by infusion of mannitol) did not enhance urate excretion during infusion of urate, in contrast to the uricosuric effect of osmotic diuretics previously found at low plasma concentrations where reabsorption of urate prevails. The findings may be explained if it is assumed that both secretion and reabsorption are mediated by transport processes, which are saturated at high plasma concentrations of urate. The extent to which urate is reabsorbed at high plasma concentrations is small relative to the secreted amount of urate. The experiments corroborate the view that probenecid in appropriate dosage almost completely inhibits urate secretion.
Effects of Sympathetic Vasoconstrictor Fibres, Noradrenaline and Vasopressin on the Intestinal Vascular Resistance during Constant Blood Flow or Blood Pressure
Authors: Dresel Peter , Wallentin Ingemar
Published: November 2009

The effects of stimulating vasoconstrictor fibres and infusing noradrenaline and vasopressin on intestinal vascular resistance were studied in cats, using either constant flow or constant pressure. The responses to stimulating constrictor fibres and to infusing noradrenaline were essentially the same whether pressure or blood flow was kept constant, and the earlier described autoregulatory escape was of about the same magnitude during both these conditions. The results further support the hypothesis that a redistribution of blood flow takes place within the intestinal wall, and the combined evidence suggests an increased submucosal flow at the expense of the mucosa. The similarities between infusing noradrenaline and stimulating constrictor fibres suggest that the vasoconstrictor fibre endings and the α‐receptors may have a differentiated distribution in the intestinal bed. This view is supported by the fact that another vasoconstrictor agent, vasopressin, produces a well sustained vasoconstrictor response without secondary adjustments. Some similarities between ‘autoregulatory escape’ during nerve stimulation and autoregulation of blood flow at different pressures are pointed out. It is further emphasized that both these phenomena are very often diminished, distorted or even totally suppressed by the introduction of an artificial pump system.
The Adrenergic Nerves of Rat Salivary Glands after Excretory Duct Ligation
Authors: Andén Nils‐Erik , Norberg Karl‐Axel , Olson Lars
Published: November 2009

After ligation of the main excretory ducts the rat submaxillary and sublingual glands atrophied by about two thirds due to a reduction of the cytoplasm of the acinar cells. This atrophy was not accompanied by a corresponding loss of noradrenaline, the level of which increased 2–3 times as a consequence of an increased density of the adrenergic ground plexus enclosing the acini in the submaxillary gland. A salivary gland with atrophied acinar cells has been found to be valuable in studies on postsynaptic events of adrenergic transmission.
Genomic Landscape of Meningiomas
Authors: Lee Yohan , Liu Jason , Patel Shilpa , Cloughesy Timothy , Lai Albert , Farooqi Haumith , Seligson David , Dong Jun , Liau Linda , Becker Donald , Mischel Paul , Shams Soheil , Nelson Stanley
Published: November 2009

Meningiomas are one of the most common adult brain tumors. For most patients, surgical excision is curative. However, up to 20% recur. Currently, the molecular determinants predicting recurrence and malignant transformation are lacking. We performed retrospective global genetic and genomic analysis of 85 meningioma samples of various grades. Copy number alterations were assessed by 100K single‐nucleotide polymorphism arrays and correlated with gene expression, proliferation indices and clinical outcome. In addition to chromosome 22q loss, which was detected in the majority of clinical samples, chromosome 6q and 14q loss was significantly more common in recurrent tumors and was associated with anaplastic histology. Five “classes” of meningiomas were detected by gene expression analysis that correlated with copy number alterations, recurrent status and malignant histology. These classes more accurately identified recurrent tumors relative to Ki‐67 index and extent of surgical resection, and highlight substantial expression heterogeneity between meningiomas. These data offer the most complete description of the genomic landscape of meningiomas, and provide broad genomic information that may be used to further stratify meningioma patients into prognostic risk groups.
Uranium Behavior in the Process of Primary Pitchblende Ores Alteration by the Post‐ore Hydrothermal Solutions: An Application to Assessment of Uranium Migration from Underground Spent Nuclear Fuel Repositories
Authors: Laverov Nikolay P. , Velichkin Vasily I. , Fujiwara Ai , Shikazono Naotatsu , Aleshin Alexey P. , Asadulin Enver E. , Golubev Vyacheslav N. , Krylova Tatiana L. , Pek Alexander A. , Chernyshev Igor V.
Published: November 2009

It has been shown that the main uranium ore mineral, pitchblende (uranium dioxide), is a natural analog of synthetic uraninite (also uranium dioxide), which constitutes 96% of spent nuclear fuel (SNF). Geochronological studies of the U‐Pb isotope systems in unaltered pitchblende from the orebodies reveal that these systems remained completely closed over the entire period (approximately 135 Ma) since the formation of the deposits. The bulk of the primary uranium ores within the Streltsovskoye ore field was influenced to various degrees by post‐ore hydrothermal solutions that led to pitchblende spherulites being replaced by pseudomorphs of an amorphous phase with a U‐Si composition; this phase also re‐precipitated in veinlets proximal to the pitchblende pseudomorphs. A technique specially developed by the authors was used to carry out quantitative counts of the abundance of uranium minerals by calculating the uranium mass balance in one of the orebodies subjected to hydrothermal alteration. The calculations reveal minimal uranium loss from the orebody. Uranium liberated in the process of the pseudomorphic replacement of pitchblende was immediately fixed, in situ, in the newly formed coffinite‐like amorphous U‐Si phase as a result of the development of an efficient geochemical barrier that prevented the long‐distance migration of uranium. In assessing the long‐term safety of underground SNF repositories, the results of the present study give us confidence that SNF uraninite, in terms of the preservation of its integrity as a mineral phase, provides for the reliable long‐term isolation of uranium, transuranium elements, and fission products that are “sealed” in the uraninite matrix. In the case of the mineral transformation of the uraninite matrix by hydrothermal solutions, the liberated uranium would be efficiently immobilized by the newly formed amorphous U‐Si phase.
Mesothermal Gold Vein Mineralization of the Seolhwa Mine, Asan Mining District, Korea
Authors: Heo Chul‐Ho , Chi Se‐Jung , So Chil‐Sup
Published: November 2009

Gold mineralization of the Seolhwa mine occurs in a single stage of massive quartz veins which filled the north‐east‐trending fault shear zones in the Jurassic granitoid of 161 Ma within the Gyeonggi Massif. The vein quartz contains three main types of fluid inclusions at 25°C: (i) aqueous type I inclusions (0–15 wt.% NaCl) containing small amounts of CO2; (ii) gas‐rich (more than 70 vol. %), vapor‐homogenizing, aqueous type II inclusions; and (iii) low‐salinity (less than 5 wt.% NaCl), liquid CO2‐bearing, type III inclusions. The H2O‐CO2‐CH4‐N2‐NaCl inclusions represent immiscible fluids trapped earlier along the solvus curve in the temperature range 250–430°C at pressures of ∼1 kb. Detailed fluid inclusion chronologies suggest a progressive decrease in pressure during the mineralization. Aqueous inclusion fluids represent either later fluids evolved through extensive fluid unmixing from a homogeneous H2O‐CO2‐CH4‐N2‐NaCl fluid due to decreases in temperature and pressure, or the influence of deep circulated meteoric waters. Initial fluids were homogeneous H2O‐CO2‐CH4‐N2‐NaCl fluids as follows: 250° to 430°C, 16–62 mol% CO2, 5–14 mol% CH4, 0.06–0.31 mol% N2 and salinities of 0.4–4.9 wt.% NaCl. The T‐X data for the Seolhwa mine suggest that the hydrothermal system has been probably located nearer to the granitic melt, which facilitated the CH4 formation and resulted in a reduced fluid state indicated by the predominance of pyrrhotite. Measured and calculated isotopic compositions of the hydrothermal fluids [δ18O = 5.3–6.5‰; δD =−69 to −84‰] provide evidence of the CH4‐H2O equilibria and further indicate that the auriferous fluids were magmatically derived. Both the dominance of δ34S values of sulfides close to the meteoric reference (−0.6–1.4‰; δ34SΣS values of 0.3–1.1‰) and the available δ13C data (−4‰) are consistent with their deep igneous source. The Seolhwa mine was probably formed by extensive fracturing and veining due to the thermal expansion of water derived from the Jurassic granitoid melt.
Potassium–Argon Ages of the Epithermal Gold–Silver Mineralization in the Haenam–Jindo Area, Southwestern Korea
Authors: Kim Chang Seong , Choi Seon‐Gyu
Published: November 2009

The Haenam–Jindo area, located on the southwestern margin of the Korean Peninsula, was the site of vigorous volcanic activity during the Late Cretaceous and Early Tertiary periods. Large parts of the area record strong hydrothermal alteration, and there exist many clay–alunite and gold–silver deposits. We undertook potassium–argon (K–Ar) age dating of five mineral samples (including adularia, sericite and alunite) from the Eunsan, Moisan and Gasado epithermal gold–silver deposits in this area. The purities of the samples were confirmed by X‐ray diffraction analysis. The K–Ar ages of adularia from the Eunsan deposit and adularia and sericite from the Moisan deposit (related to gold–silver mineralization) are 75.0 ± 1.6, 74.7 ± 1.6 and 75.1 ± 1.6 Ma, respectively. The similarity of these ages, combined with the close proximity and similar geochemical characteristics of the deposits, indicates that the mineralization occurred as part of a single hydrothermal system. The K–Ar ages of alunite at the surface and adularia at depth within the Gasado deposit are 82.2 ± 1.9 and 70.7 ± 1.9 Ma, respectively, revealing that the clay–alunite and gold–silver mineralization formed at different ages. K–Ar age data indicate that the gold–silver mineralization in this area occurred mainly at 75–70 Ma, resulting from hydrothermal activity in the Haenam–Jindo area (82–70 Ma). This is the first time that the mineralization of precious metals in Korea has been identified during this period.
Nonlinear Response of Short Squeeze Film Dampers
Authors: Taylor D. L. , Kumar B. R. K.
Published: November 2009

This paper considers the methodology of numerical integration for prediction of dynamic response of squeeze film damper systems. A planar rotor carried in a squeeze film damper with linear centering spring is considered. Governing differential equations are expressed in polar coordinates, and fluid forces are obtained from the Ocvirk short bearing integrals. The rotating unbalance response is presented as a function of speed, unbalance, and a bearing parameter. Runge Kutta integration techniques are used to obtain numerical solutions for transient response and frequency response. The 2π film approximation results in almost linear frequency response curves. However, the π film response is very nonlinear, demonstrating the well known multiple valued response and associated hardening jump/drop phenomenon. The π film transient response is analyzed within the speed range of bistable operation to determine the effects of initial conditions, the domains of convergence, and the relative strengths of stability of each solution. The transient response is found to be most sensitive to initial values of phase angle and phase angle velocity. Initial eccentricity and eccentric velocity are much less important. In general, of the two steady state solutions, the one with lower eccentricity appears to be more stable, with a larger domain of convergence. Examples show how premature termination of the integration can lead to erroneous conclusions.
A Factored Implicit Scheme for the Numerical Solution of the Reynolds Equation at Very Low Spacing
Authors: White J. W. , Nigam A.
Published: November 2009

A factored implicit algorithm is developed for the numerical solution of the compressible Reynolds equation. The method is second-order time-accurate, noniterative and allows the calculation of finite width films while requiring only tridiagonal matrix inverses. A variable spacial grid is used which incorporates both numerical resolution as needed and efficiency of computation. The scheme should be especially useful for the calculation of low spacing (< 0.5 micron), high velocity lubricant flows as found in current magnetic recording applications. Numerical results are presented and discussed.
Analysis of the Flexible Disk/Head Interface
Authors: Adams G. G.
Published: November 2009

The response of a rotating flexible magnetic disk interacting with a base plate and a read/write head is analyzed. The disk deflection due to the base plate as well as the foundation stiffness are determined. Using that as a reference configuration, the effect of the read/write head is included by coupling the disk deflection to the air bearing equation at the disk/head interface. The results are pressure and spacing contours in the interface region and disk deflection throughout the entire disk.
The Influence of Surface Tension on Bearings Lubricated With Bubbly Liquids
Authors: Smith E. H.
Published: November 2009

An order of magnitude analysis of the Rayleigh-Plesset equation of motion of a bubble surface reveals that inertia and viscous forces can be ignored in realistic bearing configurations and that surface tension plays an important role. The influence of gas bubbles in liquid lubrication is examined with particular reference to the steadily-loaded plane-inclined slider-bearing. Load carrying capacity is virtually unaffected by lubricant gasification. The centre of pressure can be considerably modified, depending partially on the value of a new dimensionless group—the configuration number φ. It appears that the tilting-pad thrust bearing will sometimes be unstable in operation, resulting in bearing failure.
The Effect of Coning on Radial Forces in Misaligned Radial Face Seals
Authors: Etsion I. , Sharoni A.
Published: November 2009

The effect of coning on radial forces in face seals having angular misalignment is analyzed. Both the hydrostatic and hydrodynamic components of the resultant radial force are presented. It is shown that the displacement of the primary seal ring due to the action of radial forces is always in a direction which may cause inward pumping. However, in most cases the radial force is very small.
Performance Characteristics of Flared Bearings
Authors: Pinkus Oscar , Bupara Sargit S.
Published: November 2009

The paper offers an analysis of finite journal bearings having an axially variable clearance. Such bearings are encountered either as a consequence of manufacturing errors and wear, or as configurations specifically designed to accommodate journal misalignment. The Reynolds equation is solved for the appropriate boundary conditions and film geometry by finite difference methods. Tables of computer solutions and a number of graphs provide the performance characteristics of misaligned bearings for a wide range of parameters. The results show that striking advantages can be achieved by the use of flared bearings for cases of moderate and severe journal misalignment.
Stability and Transient Characteristics of Four Multilobe Journal Bearing Configurations
Authors: Li D. F. , Choy K. C. , Allaire P. E.
Published: November 2009

Multilobe journal bearings are often used to improve the stability response of rotating machinery. Such machines operate near the stability threshold of the bearing-rotor system. This work determines the linearized stability threshold of four multilobe journal bearings: elliptical, offset elliptical, three lobe, and four lobe. A nonlinear transient analysis of a rigid rotor in each of these bearings is carried out above and below the threshold speed. Shaft orbits and bearing forces are calculated. A numerical fast Fourier transform analysis is used to obtain the frequency content of the nonlinear orbit.
Transient Unbalance Response of Four Multilobe Journal Bearings
Authors: Allaire P. E. , Li D. F. , Choy K. C.
Published: November 2009

This work carries out an analysis of the transient response of four multilobe journal bearings (elliptical, offset, three-lobe, and four-lobe) subject to unbalance both below and above the linearized stability thresholds for the bearings. It extends the work of a previous paper on a balanced rotor in the same four bearing types. Transient orbits, bearing forces, and a numerical fast Fourier transform analysis of the orbits are presented. A comparison of bearing forces above the stability threshold for each bearing indicates that the elliptical bearing has the most violent whirl vibration amplitudes, while the offset bearing exhibits the least amount of subsynchronous vibration.
Sinusoidal Three-Lobe Bearings—Optimization and Stability Charts
Authors: ten Napel W. E. , Bosma R.
Published: November 2009

In contradistinction to the commonly used segmented three-lobe bearing, another type of bearing, i.e., the sinusoidal three-lobe bearing has been investigated in this paper. The main advantage of this bearing is that it can very easily be manufactured. Special attention has been paid to problems of optimization with regard to minimum film thickness and friction, respectively. Stiffness and damping coefficients have been calculated as well as stability regions and stability parameters. Additionally, the optimum position of the oil grooves has been investigated.
Performance Characteristics of Two-Lobe Hydrodynamic Journal Bearings
Authors: Kumar Ashok , Sinhasan R. , Singh D. V.
Published: November 2009

The performance characteristics of noncircular bearings are known to be superior to those of the circular bearings. The two lobe bearings are finding increasing application in high speed turbomachinery. Using a variational solution, detailed design data have been computed for two-lobe bearings in this paper. The data include Sommerfeld number, equilibrium locus, fluid film stiffness and damping coefficients, end-flow, friction parameter, and temperature rise parameter.
Exact Two-Dimensional Theory of Spherical Spiral Groove Bearings
Authors: Murata Susumu , Miyake Yutaka , Kawabata Nobuyoshi
Published: November 2009

This paper is concerned with a method of obtaining exact solution for the flow of fluid film of spherical spiral groove bearing. The problem is analyzed for three cases where the centers of two elements of a bearing coincide, slightly offset vertically and arbitrarily offset vertically. Effects of bearing parameters on the load capacity are examined. A perturbation technique is applied for the case of slight offset of centers of two spheres, and the stiffness is calculated. For the case of large offset, a new iterative method is developed in this paper.
Rolling Contact Fatigue Life of AISI M-50 as a Function of Specific Film Thickness Ratio Using a High Speed RC Rig
Authors: Nahm A. H. , Bamberger E. N.
Published: November 2009

Rolling contact fatigue (RCF) life of AISI M-50 was investigated as a function of specific film thickness ratio by varying the rolling speed. RCD lives of M-50 were determined using two synthetic lubricants at rolling speeds of 2.5 m/s (98 in/s), 5.0 m/s (196 in/s), 12.5 m/s (491 in/s), and 25 m/s (982 in/s). These correspond to estimated specific film thickness ratios (Λ) of 0.45, 0.75, 1.48, 2.48 and 3.52, respectively. It was found that the RCF life increases substantially in both the mixed and full film lubrication regime while in the boundary regime, the fatigue life is relatively independent of the rolling speed. Results are discussed in terms of the lubrication life factor which is an important parameter in bearing design. It is suggested that the current ASME design guide lubrication factors are conservative, especially in the high speed regime.
Mechanisms of Wear of Sintered Carbide Dental Burs
Authors: Larsen-Basse J.
Published: November 2009

A study of worn cemented carbide dental burs was undertaken by scanning electron microscopy. Some worn burs were obtained from practicing dentists and others were worn in the laboratory against the enamel of extracted teeth. The wear mechanisms observed depend strongly on applied load and degree of cooling. As the applied load is increased the following mechanisms gradually come into play: polishing of carbide grains, preferential binder removal, uprooting of carbide grains near edges, and fragmentation of carbide grains and removal of the fragments. In addition, under conditions of heavy loading and absence of cooling thermal fatigue becomes a factor and wear by diffusion into and erosion by a high temperature film of dental material becomes important. The wear initiates at points of severe surface damage caused by the grinding operation during manufacture.
Recent Advances in Gradient Based Unconstrained Optimization Techniques for Large Problems
Authors: Shanno D. F.
Published: November 2009

The paper surveys recent results in conjugate gradient methods, variable storage variable metric methods, sparse variable metric and finite difference Newton methods, and truncated Newton methods. Both computational and theoretical results will be discussed, as well as currently distributed software.
Game Theory as a Design Tool
Authors: Vincent T. L.
Published: November 2009

Game theory encompasses not only the familiar concept of scalar optimization, but the less known concepts of multicriteria optimization and multiple optimizers as well. This paper examines the role of game theory in the engineering design process. This is done by demonstrating how game theory as a design tool applies beyond scalar optimization to the multicriteria optimization problem. The multicriteria optimization task is examined not only from the perspective of a single designer but from the perspective of team design as well. In the latter case the design problem has been assigned to several designers each responsible for one aspect of the total design.
A Space-Effective Direct Search Algorithm and Observations on the Golden Section
Authors: Townsend M. A. , Zarak C. E.
Published: November 2009

It is demonstrated that substantial savings in the computer storage space and calculation can be effected by a close inspection of the subsearch phase of a multivariate optimization algorithm. This is particularly important in implementing algorithms on small computers. A significant compaction of the golden section search is developed. Coincidentally, it is found that the actual bracketing and convergence properties are better than those conventionally used in the literature.
Notes on the Operational Utility of Monotonicity in Optimization
Authors: Papalambros P. , Li Heng Lung
Published: November 2009

Modeling and solution strategies of mathematical programing formulations of designs problems can benefit from existing monotonic properties. The concepts involved are reviewed and their utility in various optimization operations is discussed. Examples include optimality criteria, boundedness tests, Johnson’s method, and a general approach to optimization strategies.
Multiobjective Design of an Antisymmetric Angle-Ply Laminate by Nonlinear Programming
Authors: Adali S.
Published: November 2009

An antisymmetrically laminated angle-ply plate is optimized with the objectives of minimizing the maximum dynamic deflection, maximizing the natural frequencies and/or maximizing the buckling load. The design variables are the fiber orientation and the thickness of individual layers and are computed by using the methods of nonlinear programming. The concept of Pareto optimality is used in formulating the design problem and in reducing the multiple objectives into a single performance index. Numerical results are presented in the form of optimal tradeoff curves which allow the designer to assess the various possibilities open to him before deciding on a certain design. In this sense, the present design is an interactive process.
Optimum Design of Radial Drilling Machine Structure to Satisfy Static Rigidity and Natural Frequency Requirements
Authors: Rao S. S. , Grandhi Ramana V.
Published: November 2009

A computational capability is developed for the optimum design of radial drilling machine structure to satisfy static rigidity and natural frequency requirements using finite element idealization. The radial drilling machine structure is idealized with frame elements and is analyzed by using different combinations of cross sectional shapes for the radial arm and the column. From the results obtained, the best combination of cross sectional shapes is suggested for the structure. With this combination of cross sectional shapes, mathematical programming techniques are used to find the minimum weight design of the radial drilling machine structure. A sensitivity analysis is conducted about the optimum point to find the effects of changes in design variables on the structural weight and the response quantities.
A Hierarchical Method for Large-Scale Two-Dimensional Layout
Authors: Lam K. P.
Published: November 2009

The optimal layout problem of allocating different types of rectangular shapes to a large rectangular sheet (also referred to as the two-dimensional knapsack problem) is tackled by a hierarchical approach using the concepts of quad-cut, guillotine-cut, and edge-cut with variable window sizes. The method can handle sheet defects and also allows for the specification of important pieces at a fixed or variable location. In addition, the hierarchical approach has the flexibility of generating different layout patterns with little computational effort once the knapsack function for the largest window has been obtained. Although the method is suboptimal in the sense that it may not achieve the best possible result with minimum waste, extensive simulation indicates that it always gives good alternative solutions at reasonable computational cost; this is in contrast with the optimal solution for large-scale problems which often requires excessive computational effort beyond practical consideration.
Optimum Design of Variable-Material Flywheels
Authors: Metwalli S. M. , Shawki G. S. A. , Sharobeam M. H.
Published: November 2009

This paper deals with design configurations that would maximize energy stored per unit mass of flywheel and would also lead to more uniform stress distribution within yield limits. A “shape factor” is herein used to relate inertia per unit mass to specific strength (viz., yield strength per unit density), the flywheel being equally stressed in both radial and tangential directions. A proposed “optimum design function” is shown to facilitate the search for an optimum design of an isotropic variable-material flywheel. Multimaterial flywheels, made up of suitable groups of materials may well provide higher inertia per unit mass than the corresponding constant-strength disk made of any material in the group. Examples of two-element alloy flywheels (lead-tin and aluminum-magnesium) with higher inertia per unit mass than the constant-strength disk are displayed.
Development of Cam Profiles Using the Convolution Operator
Authors: Gupta K. C. , Wiederrich J. L.
Published: November 2009

A new method for designing cam profiles which modifies the residual vibration spectrum in a desired way is presented. This method utilizes the convolution operator to modify the dynamic properties of the cam motion in a specified way, while maintaining the total displacement of the motion. The method is illustrated by developing families of cam profiles of increasing continuity, and also by developing cam motions whose residual vibration spectra have significant zones of near zero vibration.
A Method for the Identification of Planar Linkage Chains
Authors: Yan H.-S. , Hwang W.-M.
Published: November 2009

For every planar linkage chain with turning-pairs only, there is a corresponding set of identification numbers consisting of link assortment, joint assortment, link adjacent polynomial, joint adjacent polynomial, linkage incident polynomial, and linkage structural polynomial. These numbers can be used for the identification of a linkage chain and for the testing of the isomorphism of unknown linkage chains.
Kinematic Synthesis of Spherical Two-Gear Drives With Prescribed Entire-Motion Characteristics: Displacement Analysis and Dwell Characteristics
Authors: Lee T. W. , Akbil E.
Published: November 2009

This paper presents an analytical and computer-aided procedure on the kinematic synthesis of the spherical two-gear drive with prescribed dwell characteristics. The first part gives a displacement analysis which includes an investigation of the general case of spherical five-link, 5R mechanisms and the spherical geared five-link case. Two approaches, one making use of the spherical trigonometric relations and the other involving sequential coordinate transformations by real and orthogonal [3 × 3] matrices, yield identical input-output expressions. The remainder of the paper focuses on the dwell characteristics of the spherical two-gear drive using algebraic methods based on the displacement equation. Dwell criteria for the general mth-order dwell are derived. A specific example which involves a joint consideration of other entire-motion characteristics, such as limit positions and transmission-angle variations, is given to illustrate both the theory as well as the computer-aided synthesis procedure.
Design of Drag-Link Mechanisms With Minimax Transmission Angle Deviation
Authors: Tsai L.-W.
Published: November 2009

In this paper, the design equations are derived for the synthesis of a drag-link mechanism, with given output-link rotation and the corresponding input-link rotation. The design criterion used is based on the maximum capability of a drag-link mechanism to provide a given delay or advance in the output motion. The solutions are given as a single-valued parametric set of equations for the link lengths. The transmission-angle optimization is accomplished by the minimization of the maximum transmission-angle deviation from 90 deg. It is shown that the optimum design can be obtained by solving a cubic equation in a single parameter. Design charts for the optimum design of a drag-link mechanism were developed. It is also shown that there is a one-to-one correspondence between the design of a crank-and-rocker mechanism and the drag-link mechanism.
A New Continuous Contact Low-Noise Gear Pump
Authors: Mitome K. , Seki K.
Published: November 2009

Developed is a new low-noise gear pump which has no trapping and whose gears are in continuous one-point contact in the plane of rotation. First this paper studies a practical method to design the tooth profile of a spur gear for a given path of contact. A new tooth profile is obtained by giving a closed path of contact like a figure 8. Basic dimensions are determined and limites of them are obtained. Both theoretical and approximate displacements are expressed in terms of the basic dimensions. Secondly, a helical gear pump is studied. The helical gear can be discussed in the same way as the spur gear by new basic dimensions. Finally some test gear pumps are made and tested. Test prove that this gear pump has excellent performance and durability.
Analysis of Five-Degree-of-Freedom Robot Arms
Authors: Sugimoto K. , Duffy J.
Published: November 2009

Many kinds of robot arms with five degrees of freedom are widely used in industry for arc welding, spray painting, assembling etc. It is necessary to be able to compute joint displacements when such devices are computer controlled. A solution to this problem is presented and the analysis is illustrated by a numerical example using the most common industrial robot with five axes. Further, special cases are discussed using screw theory.
Pshenichny’s Linearization Method for Mechanical System Optimization
Authors: Choi K. K. , Haug E. J. , Hou J. W. , Sohoni V. N.
Published: November 2009

In 1970, Pshenichny published a linearization method for nonlinear programming in Russian, which has been overlooked in the English literature. The method is essentially a recursive quadratic programming technique with an active set strategy. Pshenichny has proved global convergence of the method and convergence rate estimates. The method is presented in this paper, with convergence theorems stated. Application of the method is made to shape optimal design, kinematic optimization, and dynamic system optimization. The method is shown to be particularly attractive in utilization of mechanical design sensitivity analysis techniques and performs well on all classes of problems treated.
1983 State-of-the-Art Review on Gears
Authors: Errichello Robert , El Bayaumy Lotfi , Akin L. S.
Published: November 2009

The Power Transmission and Gearing Committee produces a state of the art review paper on gears once every year or two. In this review, assembled by L. S. Akin, three areas are reported upon at this time. R. Errichello gives a report on recent developments in the AGMA gear rating committee and their newest publications on "Gear Bending Stress Analysis," Lotfi El Bayaumy reports on gear noise analysis and prediction. It covers the most recent advances made on navy-sponsored research work under the leadership of Bill Mark of BBN. Finally, the latest developments in gear tooth cooling analysis work being performed by D. P. Townsend at NASA Lewis Research Center and L. S. Akin through California State University Long Beach under NASA sponsorship are discussed.
Reliability Model for Planetary Gear Trains
Authors: Savage M. , Paridon C. A. , Coy J. J.
Published: November 2009

A reliability model is presented for planetary gear trains in which the ring gear is fixed, the sun gear is the input, and the planet arm is the output. The input and output shafts are coaxial and the input and output torques are assumed to be coaxial with these shafts. Thrust and side loading are neglected. This type of gear train is commonly used in main rotor transmissions for helicopters and in other applications which require high reductions in speed. The reliability model is based on the Weibull distribution of the individual reliabilities of the transmission components. The transmission’s basic dynamic capacity is defined as the input torque which may be applied for one million input rotations of the sun gear. Load and life are related by a power law. The load-life exponent and basic dynamic capacity are developed as functions of the component capacities.
Generalized Coordinate Partitioning for Analysis of Mechanical Systems with Nonholonomic Constraints
Authors: Nikravesh P. E. , Haug E. J.
Published: November 2009

This paper presents a computer-based method for formulation and efficient solution of nonlinear, constrained differential equations of motion for spatial dynamic analysis of mechanical systems with holonomic and nonholonomic constraints. Holonomic and nonholonomic constraint equations and differential equations of motion are written in terms of a maximal set of Cartesian generalized coordinates, three translational and four rotational coordinates for each rigid body in the system, where the rotational coordinates are Euler parameters. The maximal set of generalized coordinates facilitates the general formulation of constraints and forcing functions. A Gaussian elimination algorithm with full pivoting decomposes the constraint Jacobian matrix and identifies independent coordinates and velocities. This information is employed to numerically construct a reduced system of differential equations of motion whose solution yields the system dynamic response. A numerical integration algorithm with positive-error control, employing a predictor-corrector algorithm with variable order and step size, integrates for only the independent variables, yet effectively determines dependent variables.
Kinematic Design and Analysis of Coupled Planetary Bevel-Gear Trains
Authors: Day C. P. , Akeel H. A. , Gutkowski L. J.
Published: November 2009

One of the most common methods in analyzing speed ratios of planetary gear trains has been the tabulation method. For complex mechanisms where many gear trains are coupled together, this method becomes inconvenient. With bevel gears in the gear train, it fails to apply. Some textbooks also use formulas which apply only to gears with parallel axes of rotation. This fact is often not stated in machine design texts. These methods can become incorrectly used in the design and analysis of planetary bevel gear trains with nonparallel axes of rotation. With the use of computers and graphics, a convenient and reliable method can be derived. Freudenstein and Yang have derived the early graphical method for analyzing gear trains. This paper describes an algorithm to extend the graphical method for analyzing coupled planetary bevel gear trains. A matrix formulation is used to include speeds of all gears rotating about their respective axes. Such formulation will aid designers and analysts in determining correct speed ratios of all gears in a planetary gear train system.
Motion Synthesis Using Kinematic Mappings
Authors: Ravani B. , Roth B.
Published: November 2009

This paper studies planar motion approximation problems in the context of a kinematic mapping. Since a planar displacement is determined by three parameters, it can be mapped into a point of a three-dimensional space. A (single-degree-of-freedom) planar motion can, therefore, be represented by a space curve in the space of the mapping and the problem of motion approximation becomes a curve fitting problem in this space. A mapping introduced by Blaschke is used and a general theory for planar motion approximation is developed. The theory is then applied to dimensional synthesis of four-link mechanisms. Furthermore, since the structural error (i.e., the quality of motion approximation) is dependent on the closeness of the fit in the space of the mapping, a general algebraic theory for determining closest fits to points in this space is developed. The theory is illustrated by a numerical example.
Minimization of Inertia-Induced Forces in Spherical Four-Bar Mechanisms. Part 1: The General Spherical Four-Bar Linkage
Authors: Gill G. S. , Freudenstein F.
Published: November 2009

Computer-aided design procedures have been developed for the optimum mass distribution of the links of high-speed spherical four-bar linkages. The analysis, which includes a quadratic-programming technique, allows an optimum trade-off between shaking forces, shaking moments, bearing reactions, and input-torque fluctuation. The results are illustrated in the case of a Hooke joint and a wobble-plate linkage.
Dynamic Force and Torque Analysis of Spherical Four Link Mechanisms
Authors: Yang A. T. , Zhishang Sun
Published: November 2009

In this paper we present a dynamic analysis of a general spherical four-link mechanism whose links have arbitrary mass distribution. Results, which are in explicit analytical expressions in terms of inertia-induced forces and moments in links, are useful for optimum design of the mechanism under high-speed operation.
An Experimental and Analytical Study of the Dynamic Response of a Linkage Fabricated from a Unidirectional Fiber-Reinforced Composite Laminate
Authors: Thompson B. S. , Zuccaro D. , Gamache D. , Gandhi M. V.
Published: November 2009

A large class of industrial machinery and commercial equipment is operated at high speed to satisfy the demands for high productivity. In order to further improve performance, it is proposed herein that the designer should consider fabricating the mechanism components in one of the commercially available composite materials because they offer many desirable characteristics with the promise of even higher speeds of operation. This paper presents an experimental and computational study of a flexible planar four-bar linkage fabricated from one of these composites. This fiber-reinforced material is modeled as an elastic solid by using a continuum theory which accommodates laminae with orthotropic properties, and differing densities, thicknesses, and elastic moduli. The theory is embodied in a variational theorem which serves as the basis for a finite element analysis of the mechanism.
Instantaneous Kinematics of a Plane in Space Motion
Authors: Ting K.-L. , Soni A. H.
Published: November 2009

A plane under a one-parameter motion envelops a surface called a plane-envelope which is a developable (torse). The properties of a plane-envelope are characterized through the properties of the edge of regression. The paper presents the methodology to obtain the families of planes whose envelopes have the common characteristics. Special cases including stationary plane, cylindrical developable, stationary generator, stationary-point, and helical developable are investigated. It is also shown that, in general, a plane embedded in a body executing Darboux motion envelops a helical developable.
Effects of a Cracked Blade on Mistuned Turbine Engine Rotor Vibration
Authors: Saito Akira , Castanier Matthew P. , Pierre Christophe
Published: November 2009

An efficient methodology for predicting the nonlinear forced vibration response of a turbine engine rotor with a cracked blade is presented and used to investigate the effects of the damage on the forced response. The influence of small random blade-to-blade differences (mistuning) and rotation on the forced response are also considered. Starting with a finite element model, a hybrid-interface method of component mode synthesis (CMS) is employed to generate a reduced-order model (ROM). The crack surfaces are retained as physical degrees of freedom in the ROM so that the forces due to contact in three-dimensional space can be properly calculated. The resulting nonlinear equations of steady-state motion are solved by applying an alternating frequency/time-domain method, which is much more computationally efficient than traditional time integration. Using this reduced-order modeling and analysis framework, the effects of the cracked blade on the system response of an example rotor are investigated for various mistuning levels and rotation speeds. First, the advantages of the selected hybrid-interface CMS method are discussed and demonstrated. Then, the resonant frequency shift associated with the stiffness loss due to the crack and the vibration localization about the cracked blade are thoroughly investigated. In addition, the results of the nonlinear ROMs are compared with those obtained with linear ROMs, as well as blade-alone ROMs. It is shown that several key system vibration characteristics are not captured by the simpler models, but that some insight into the system response can be gained from the blade-alone response predictions. Furthermore, it is demonstrated that while the effects of the crack often appear similar to those of mistuning, the effects of mistuning and damage can be distinguished by observing and comparing the response across multiple families of system modes.
Low Frequency Vibration Isolation Through an Active-on-Active Approach: Coupling Effects
Authors: Sun Qiao , Wolkow Robert A. , Salomons Mark
Published: November 2009

The extreme sensitivity of a scanning probe microscope demands an exceptional noise cancellation device that could effectively cut off a wide range of vibration noise. Existing commercial devices, although excellent in canceling high frequency noise, commonly leave low frequency vibration unattenuated. We design an add-on active stage that can function together with a standalone existing active stage. The objective is to provide a higher level of noise cancellation by lowering the overall system cut-off frequency. This study is concerned with the theoretical aspects of the coupling characteristics involved in stacking independently designed stages together to form a two-stage isolator. Whether an add-on stage would pose a stability threat to the existing stage needs to be addressed. In addition, we explore the use of coupling effects to optimize the performance of the overall system.
Controlling the Velocity of Light Pulses
Authors: Boyd Robert W. , Gauthier Daniel J.
Published: November 2009

Blod

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New Science for Chemicals Policy
Authors: Schwarzman Megan R. , Wilson Michael P.
Published: November 2009

U.S. regulation of chemicals is in need of an overhaul, informed by European legislation and guided by new thinking about risk.
Epicontinental Seas Versus Open-Ocean Settings: The Kinetics of Mass Extinction and Origination
Authors: Miller Arnold I. , Foote Michael
Published: November 2009

Extinction Distinctions

The distribution of affected organisms can help reveal the mechanisms of mass or background extinctions. This has often been studied by comparing effects on land versus in the ocean, or across latitudes, for example.
Miller and Foote
(p.
1106
) now analyze extinction patterns in shallow seas around continents, versus open-ocean coastal regions from the Permian through the Cretaceous, a period spanning three major mass extinctions. The mass extinctions all affected organisms in the open coastal environment greater than those inhabiting shallow seas, but at other times the pattern was opposite. Thus, organisms in these environments may have very different evolutionary histories.
Megafaunal Decline and Fall
Authors: Johnson Christopher
Published: November 2009

Declines in North American megafauna populations began before the Clovis period and were the cause, not the result, of vegetation changes and increased fires.