1,678 research outputs found
A Naturalist of International Renown. An Interview with Prof. John Muir.
No full text\u27-~: OS AIRES HERALD ΓÇö Wednesday, No ΓÇö 4. NATURALIST OF INTERNATIONAL RENOWN AN INTERVIEW WITH Prof. JOHN M\u27JIR James Russel Lowell has commented on the sad state of the man who ne\u27er had seen Nature untold itself, and his words gain a fresh significance to one who listens as did a Heisai.d representative while joan Muir, geologist, explorer, naturalist of international renown,\u27 gave of his apparently unlimited knowledge of the subjects which. have been the basis of his life work, Professor Muir John iYiuir is the son of Daniel am Anne (GilyreJ M. Muir, and was bon in Dunbar,\u27 Scotland on April 21st,i 1808. He attended school in Scotland,, I but, in 1849, his father emigrated to the state of Wisconsin and found hi:; home in a sparcely settled district where there was no, one living within a radius of ten miles. In such isolation the boy grew to know Nature and depend upon its companionship. He entered the University of Wiscort-. sin, but left before graduating. The deep commercial interest which his adopted state had in the lumber trade led to his becoming concerned in the forests of Wisconsin, not alone \u27 or the value of their products, but as an agent for .the conservation of then\u27 natural resources, and that 1e ,-aw great gospel which\u27 he has been preaching ever sinceΓÇöforest preservation and the establishment of national parks such as Yellowstone and Yso-e mite, where Nature in some at. least of its varied forms might be left untouched, by the hand of man for future generations to study. And in speaking of this\u27 phase of his life ] work, he told with simplicity how Senator Kent, of \u27California/a stranger 1o. .him. Jra)l bought sortie forest land within ninety ni\u27iniite\u27s by train from San Francisco arid offered it to the United States Government as: a national park, suggesting that it be given the name of Muir\u27s Woods . This prompted a query from President Roosevelt as to why Kent\u27s Woods would not do, to which Senator Kent replied that he did not care to stencil his benefactions with his name, that he had five husky boys, and if they, could not keep the name alive, ..nothing else would, to which came the characteristic Rooseveltian reply Neither do I care to stencil\u27 my benefactions, I have three husky boys and, I depend j on them Γûá to do the same with my j name. And how about Muir Glacier, Mr. Muir? ΓÇö Oh, I discovered that in 1S79, was the reply, and the scribe j wondered how it felt to reach that I altitude of scientific accomplishment! and reputation where the discovery of a glacier could be regarded as a com- j mon~pla.ee event. Muir Glacier, in Al- i aska, is two and a half miles wide at its mouth, where it discharges into! the sound, two hundred feet in height; above water, and eight hundred feet in r depth below the surface. It is twenty- five miles in width at the widest part. And how about your books? was the next query. ΓÇö Oh, I have only written six on the glaciers of Alaska and- other topics. I am not going to write books to any extent until I give up my present occupation. And what may that be? ΓÇö Tramp, came the answer with, grim Scotch gravity I am severity-four and am still good at it. Have you any particular object in coming to South America ? the Hkr- -\i.r. representative asked. ΓÇö I am studying the trees of South America, but am here particularly to visit Chili, and locate, if possible, the place of origin of the tree known as Araucaria^ Tmhricata after the American tribe of j Indians who are native in that country. It is currently called the monkev ] puzzle \u27 because its prickly needles render ascent impossible to the mon- Ivey. I leave for Chili this week, return to Buenos Aires shortly, and take passage for South Africa. And what do you think of Buenos Aires ? ΓÇö The lack of time and sunshine has precluded mv seeing much of the city, but I have visited the Zoological Gardens and Palermo. I found the animals in good condition and the gardens well laid out for future development. The park, by its tree life, shows the fertility of soil in this country, the begum tree grows better in Palermo, than in some parts of Australia: of which it is a native. The Professor then went on to talk of the tonics he loved, of the subjects he had made particularly his own, of trees and plants of all descriptions, their varied characteristics and how thev flourished in different countries of the world: of the devastation caused by forest fires, of the insight of Robert Burns info nature\u27, and so. onΓÇö all with a simplicitv and a lack of egotism which was delightfully refreshing to a newsnaper correspondent whose daily routine brings him into contact with many personalities but with few who, with so much right, have so little inclination to claim attention.https://scholarlycommons.pacific.edu/jmb/1626/thumbnail.jp
Influence of temperature and sliding speed on the subsurface microstructure evolution of EN AW-6060 under sticking friction conditions
No full textThis article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in AIP Conference Proceedings 1896, 140012 (2017) and may be found at https://doi.org/10.1063/1.5008168.The microstructure evolution of the friction boundary layer of the aluminum alloy EN AW-6060 was investigated. Sticking friction tests at different temperatures and sliding speeds were carried out. A severe deformation below the friction surface was observed by means of LOM and EBSD mapping. Thus, the thickness variation and the grain structure of the high deformation zone could be described. Fibrous structure was observed at 300 °C and 400 °C, while equiaxed grains with high misorientation angle (>15°) were generated at higher temperatures. Additionally, abnormal grain growth and coarse grains were detected at high sliding speeds (10 mm/s, 42 mm/s) at 450°C and 500 °C respectively
Author-Suggested, Weighted Citation Index: A Novel Approach for Determining the Contribution of Individual Researchers
No full textA novel scientometric index, named ‘author-suggested, weighted citation index’ (Aw-index) is proposed to indicate the scientific contribution of any individual researcher. For calculation of the Aw-index, it is suggested that during the submission of a scholarly article, the corresponding author would provide a statement, agreed upon by all the authors, containing weightage factors against each author of the article. The author who contributed more to the article would secure a higher weightage factor. The summation of the weightage factors of all the authors of an article should be unity. The citation points a researcher receives from a scholarly publication is the product of his/her weightage factor for that article and the total number of citations of the article. The Aw-index of any individual researcher is the summation of the citation points he/she receives for all his/her publications as an author. The Aw-index provides the opportunity to the group of authors of a multi-authored article to determine the quantum of partial citations to be attributed to each of them. Through an illustrative example, a comparison of the proposed index with the major scientometric indexes is presented to highlight the advantages of the Aw-index
Influence of Process Parameters on the Quality of Aluminium Alloy EN AW 7075 Using Selective Laser Melting (SLM)
No full textAbstractSelective laser melting (SLM) is an additive manufacturing process, forming the desired geometry by selective layer fusion of powder material. Unlike conventional manufacturing processes, highly complex parts can be manufactured with high accuracy and little post processing. Currently, different steel, aluminium, titanium and nickel-based alloys have been successfully processed; however, high strength aluminium alloy EN AW 7075 has not been processed with satisfying quality. The main focus of the investigation is to develop the SLM process for the wide used aluminium alloy EN AW 7075. Before process development, the gas-atomized powder material was characterized in terms of statistical distribution: size and shape. A wide range of process parameters were selected to optimize the process in terms of optimum volume density. The investigations resulted in a relative density of over 99%. However, all laser-melted parts exhibit hot cracks which typically appear in aluminium alloy EN AW 7075 during the welding process. Furthermore the influence of processing parameters on the chemical composition of the selected alloy was determined
Zhedanov's Algebra AW(3) and the Double Affine Hecke Algebra in the Rank One Case. II. The Spherical Subalgebra
No full textThis paper builds on the previous paper by the author, where a relationship between Zhedanov's algebra AW(3) and the double affine Hecke algebra (DAHA) corresponding to the Askey-Wilson polynomials was established. It is shown here that the spherical subalgebra of this DAHA is isomorphic to AW(3) with an additional relation that the Casimir operator equals an explicit constant. A similar result with q-shifted parameters holds for the antispherical subalgebra. Some theorems on centralizers and centers for the algebras under consideration will finally be proved as corollaries of the characterization of the spherical and antispherical subalgebra
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Extensions and amplifications of a traffic model of Aw and Rascle
No full textIn a recent paper [1] Aw and Rascle introduced a new model of traffic on a uni-directional highway. Here the author studies an extension of this model, one which accounts for drivers attempting to travel at their maximum allowable speed. The author looks at a Lagrangian reformulation of this problem; a formulation that leads to an effective computational algorithm for solving the resulting system. He also investigates approximation scheme introduced by Dafermos [5] for scalar conservation laws and demonstrates that this Dafermos scheme works well on this 2 x 2 system
Automating the determination of wave speed using the pu-loop method
No full textThe PU-loop (pressure-velocity loop) is a method for determining wave speed and relies on the linear relationship between the pressure and velocity in the absence of reflected waves. This linearity of the PU-loop during early systole, which is directly related to wave speed, has always been established by eye. This paper presents a new technique that establishes this linearity and thus determining wave speed online. Pressure and flow were measured in the ascending aorta of 11 anesthetised dogs. The slope of the PU-loop, indicating wave speed was determined by eye and by using the new technique. The difference between the slopes of the two methods is in the order of 3%. The new technique is convenient and allows for the online assessment of wave speed, which could be used as a bedside tool for the assessment of arterial compliance
Simultaneous three-dimensional printing and frontal polymerization of dicyclopentadiene resin
No full textMade available in DSpace on 2019-08-23T20:48:28Z (GMT). No. of bitstreams: 2
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Previous issue date: 2019-04-26Three-dimensional (3D) printing has widespread uses across many industries due to its versatility and capabilities. However, freeform fabrication of thermoset polymers remains a technical challenge. This thesis combines 3D printing with frontal polymerization (FP) — a method to rapidly cure resin — for curing filaments in tandem with the printing process. A partially cured dicyclopentadiene (DCPD) resin was developed into a printing ink. Critical rheological characteristics were identified, and DCPD inks of varying incubation times were screened to find the most suitable properties. Results of the rheological study indicate that 90 minutes of incubation time resulted in optimum print behavior. Problems associated with FP were effectively tackled through temperature control across the printing setup. In situ infrared images showed an exothermic reaction front propagating during the print process, giving evidence of in situ polymerization. The optimized technique produced one-dimensional, two-dimensional and 3D freeform prints with excellent fidelity. A self-equilibrating behavior was identified in the reaction front, such that the front autonomously tune its speed to the programmed print speed. This phenomenon autonomously controls the viscoelastic bridge length, Lb, and inevitably curbs deformations to achieve high print fidelity.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-05-01The student, Jia En Aw, accepted the attached license on 2019-04-26 at 14:07.The student, Jia En Aw, submitted this Thesis for approval on 2019-04-26 at 14:16.This Thesis was approved for publication on 2019-04-26 at 14:46.DSpace SAF Submission Ingestion Package generated from Vireo submission #13952 on 2019-08-22 at 16:24:04Embargo set by: Seth Robbins for item 112399
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Cerebrospinal fluid flow quantification in the brain using magnetic resonance imaging
No full textHydrocephalus is a severe brain condition in which cerebrospinal fluid (CSF) cannot properly drain into the spinal cord, resulting in a buildup of pressure. To relieve this pressure, a shunt is placed in the brain that drains the CSF. However, the failure rate of these shunts is high, requiring additional surgeries to check functionality or for replacement. As this is costly and invasive, a way to quantitatively measure the shunt flow without surgery would be valuable. In this work, we modify a previously successful technique that quantified blood flow in the brain to quantify CSF flow. This technique, called flow enhanced signal intensity (FENSI), uses magnetic resonance (MR) to gain a quick and accurate measurement. By adjusting imaging parameters from quantitative FENSI (qFENSI), we can optimize this sequence to be sensitive to CSF flow. We demonstrate the sensitivity of our technique down to 0.1 ml/min and up to 0.4 ml/min. Additionally, taking into account the T1 relaxation rate, we can fit a curve to the data points using simulations to predict the flow rate of the measured signal.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-05-01The student, Natalie Aw, accepted the attached license on 2019-04-11 at 12:55.The student, Natalie Aw, submitted this Thesis for approval on 2019-04-12 at 12:21.This Thesis was approved for publication on 2019-04-12 at 13:59.DSpace SAF Submission Ingestion Package generated from Vireo submission #13565 on 2019-08-22 at 15:05:53Made available in DSpace on 2019-08-23T20:35:50Z (GMT). No. of bitstreams: 2
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Previous issue date: 2019-04-12Embargo set by: Seth Robbins for item 112124
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Improved Numerical Method for Aw-Rascle Type Continuum Traffic Flow Models
No full textContinuum traffic flow models are essentially nonlinear hyperbolic systems of partial differential equations. Except for limited specific cases, these systems must be solved numerically. Mathematical structure of continuum models can be different for each class of models. As a result, suitable numerical schemes for some classes may not be efficient for others. In this study, an improved numerical method is proposed for a class of second-order traffic flow models. The method is based on McCormack scheme, which is a widely-used method for non-homogeneous second-order traffic flow models, but fails to produce reasonable results for homogeneous models including Aw-Rascle type models which are the focus of this paper. It is shown that this is mainly due to spurious numerical oscillations. Smoothing methods to overcome these issues are studied and applied. Central dispersion and artificial viscosity (AV) methods are incorporated into the standard McCormack scheme and tested. To reduce numerical diffusion, a total variation diminishing Runge-Kutta time stepping scheme is applied. Results show the capability of the proposed methods, and especially the AV method, to eliminate the oscillations of the standard McCormack scheme as well as controlling numerical diffusion.Transport and Plannin
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