Akron Phy sics Club
Archive 2005
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Newsletter
Meeting Announcement: MONDAY, January 24, 2005 - TANGIER, 6:00 PM
For our first meeting of 2005 (actually the last meeting of the Chinese Year of the Monkey, which ends on February 7th) we will hear from Professor David S. Perry, Chair of the University of Akron’s Department of Chemistry, who has imaginatively entitled his presentation:
MOLECULAR DANCE STEPS
New Kinds of Vibrational Motion
Born at High Levels of Excitation
Dr. Perry explains that the established theory of molecular vibrations is valid only within the limits of small-amplitude vibrational motion. But when the amplitude of vibrational motion becomes large the assumptions of the established theory break down, and we find that new kinds of motion are born. With the aid of demonstrations, animations, and molecular models, our speaker will explore some of these new molecular dance steps and the concepts behind them.
Minutes, January 24, 2005
Twenty members and guests gathered to hear our speaker at the first meeting of 2005: Bill Arnold, Tom Brooke, Dave Brown, Tom Dudek, Bob Erdman and his guest, Tom Myers, retired KSU chemist (welcome Tom), Sam Fielding-Russell, Milian France, Dan Galehouse, Jack Gieck, Ben Hu (welcome back, Ben), Bob Hirst, Bill Jenkin, Leon Marker, Pad Pillai, Jerry Potts, Ernst von Meerwall, Charlie Wilson, and Wiley Youngs.
In our short business meeting Treasurer Dan Galehouse advised that our wealth had increased $4.00 since last month, resulting in a heavy new balance of $79.38 for Treasurer Dan’s strongbox!
Program Co-Chairman, Robert Hirst, outlined next month's meeting program, to be held on February 21, which will be a talk by Bill Arnold on "Impact Analysis and Experimental Research." His research is being done at NASA Glenn Research Center and the University of Akron with application in jet engine containment. March Prof. Dabold Physics & Astronomy at Ohio Univ. April 25 & May 24 are still open for speakers.
Chairman Ernst von Meerwall introduced the evening's speaker, Professor David S. Perry, Chair, Department of Chemistry, University of Akron, to speak on Molecular Vibrations and their Enhancement of Chemical Reactions.
Dr. Perry proceeded to re-acquaint us with the basics of simple harmonic motions of a spring pendulum, which he used to demonstrate the correspondence of related phenomena within molecules and their atomic bonds. What was most fascinating was that, despite the fact that molecular vibrations really occur at the quantum physics level and do not have continuously observable motion, simple models of complex molecules behave similar to classical normal mode vibration theory in stretch, bending and resonant vibration of all possible mode shapes as if the atoms in the molecule were masses, and the bonds between the atoms were springs.
Then cis and trans motions as well as stretching motions predict mode shapes and resonant frequencies. Mostly, Prof. Perry related the correspondence between quantum physics theory and the eigenvalue, eigenfunction solutions of Shroedinger’s wave equation with the simple model mode shapes and how the correspondence yields good results. This is probably because, on average, the individual quanta become a continuum, which behave according to continuum theory.
Many very entertaining and most active slides were shown giving life to such motion and imagination as to what such motion might be.
The reality of the principles and ideas set forth is that enhanced chemical reactions may be obtained by resonating the preferred fracture bonds in the reactants during the chemical reaction…sort of like a mechanical catalyst, almost a manifold scalpel being applied during the reaction to drive it in a preferred direction.
While most of the presentation involved a detailed account of the theory involved, Prof. Perry did expound a bit upon the methods used to excite molecular vibrations to their resonant frequencies, which run to some 25 GHz. This involves the use of dye lasers, which can be tuned over a range of frequencies in order to excite various resonant modes within the atomic structure of the reactant molecules.
Although these ideas have existed for some time, excitation techniques and methods for exciting large numbers of molecules seems to present a practical limit for use of such methods in everyday industrial processing. Evidently the principles work. Now to create the practical tools!
WE ALWAYS WELCOME VISITORS WE ALWAYS WELCOME VISITORS
Jerry Potts & Jack Gieck
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Newsletter
Meeting Announcement: MONDAY, February 28, 2005 - TANGIER, 6:00 PM
For our Speaker for our February meeting will be Akron Physics Club regular Bill Arnold, AKA Dr. William A. Arnold, Interdisciplinary Engineer / Scientist, ZIN Technologies, AKA Professor of Civil Engineering, the University of Akron. ZIN Technologies, is located at NASA Glenn Research Center, where the company is a prime contractor. Bill's topic will be:
IMPACT ANALYSIS AND EXPERIMENTS
As our speaker explained to John Kirszenberg in April, "I use the term 'impact' because it covers impacts varying greatly in velocity from tens of feet per second to thousands of feet per second, and some experiments are less than ballistic." For a preview, two experiments recently fired are described at http://ballistics.grc.nasa.gov/pages/LargeFacility.html , where the reader will be rewarded by calling up Gun Detail - which Bill describes as "basically a very large potato-gun."
While you are still online, please don't forget to click on Charlie Wilson at This email address is being protected from spambots. You need JavaScript enabled to view it. to get your dinner reservation in the pot. And for the rest of the Newsletter (with Jerry Potts' minutes for our January meeting) click on http://physics.uakron.edu/APC/news.htm
Minutes, February 28, 2005
The flu and/or bronchitis having taken its toll (which included this writer), regular APS attendees were reduced to Bill Arnold, Bob Erdman, Sam Fielding-Russell, Milian France, Dan Galehouse, Bob Hirst, Bill Jenkin, John Kirszenberg, Leon Marker, Bob Mallik, Pad Pillai, Ernst von Meerwall, Joe Walter, Charlie Wilson, and son Rob. But the addition of “Arnold’s Army,” including Austin Bail, plus students Jinyun Cheng, and Richie Beneen boosted the audience total to a decent size nonetheless.
However, the absence of both co-secretaries demanded some ingenuity, which was supplied by co-sec Jerry Potts (whose current consulting project kept him away). Jerry induced his friends, Tom & Linda Csora, to bring their Sony and a tripod to the meeting and record our own Dr. William A. Arnold, Interdisciplinary Engineer/Scientist, ZIN Technologies — AKA Professor of Civil Engineering, the University of Akron — as he presented his paper on Impact Analysis and Experiments. Since this is also one of Jerry’s fields, Tom, in turn, made one copy for him in DVD, and a second (VHS) dub for the writer — who distilled the following from the result:
With a stunning Power Point presentation (that would have made the content of his talk clear to a deaf audience!) Dr. Arnold reviewed the history of a number of U of A/ZIN projects that led to the University's developing several new technologies, one of which makes it possible, for example, to measure the coefficient of friction of objects colliding at the speed of sound!
Joining both the U of A and ZIN in 2002, Bill has been working on space experiments for NASA in such diverse areas as coarsening in solid-liquid mixtures (for which he and ZIM built an apparatus to go aboard the International Space Station), the construction of a pneumatic pressure testing facility (which includes a bomb box!), and apparatus for improving jet engine blade containment. All of these involve the carefully-monitored throwing of things around at carefully-controlled high speeds. To this end, the NASA Glenn facility includes a gas gun with a 6-foot barrel having a barrel 40 feet long, capable of shooting a projectile up to 16 inches in diameter at the speed of sound.
A new ballistic impact laboratory is being completed at the University of Akron, which includes a smaller gas gun, a spring-hydraulic accelerated projectile device, and a jet engine centrifuge capable of revving up to 20,000 rpm. Resulting flying stuff is recorded by a very high speed camera that can operate up to 200,000 frames per second (at a shutter speed of two microseconds). One wonders where there is sufficient light for that kind of videography.
Bill Arnold promised to come back and bring us up to date on what happens in the next chapter of his Impact Analyses and Experiments. We look forward to it!
As always, WE WELCOME VISITORS.
Jack Gieck and Jerry Potts, with thanks to Tom and Linda Csora
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Newsletter
Meeting Announcement: MONDAY, March 28, 2005 - TANGIER, 6:00 PM
Speaker for our March meeting will be David A. Drabold, Professor and Graduate Chair, Department of Physics and Astronomy, Ohio University of Athens. An APS Fellow as of 2003, Dr. Drabold will be speaking on:
COMPUTER MODELING OF COMPLEX MATERIALS
Dr. Drabold will describe current approaches to the simulation of complex materials, including his recent work on glasses. He promises to compare his simulations to real world experiments, and “hopes to convince the audience that suitable computer simulations provide important new insights into the structure, dynamics, and electronic properties of materials.”
Minutes, March 28, 2005
In attendance at our first meeting after the very welcome Vernal Equinox were Tom Brooker, Dave Brown, Sam Fielding-Russell, Milian France, Dan Galehouse, Jack Gieck, Bob Hirst, Bill Jenkin, John Kirszenberg, Leon Marker, Robert Mallik, Darrell Reneker, Jack Strang, newcomer Claire Tessier (welcome UA Chemistry Prof Claire!), Ernst von Meerwall, Don Wiff, and Charlie Wilson.
As a first order of business, Chairman Ernst called on bylaws author Charlie Wilson, who, even as prescribed by our venerable bylaws, invited nominations for next year’s club officers — after which our chairman editorialized on the matter, convincing the audience [especially this secretary of a dozen years(!)], that it was the duty of club regulars to share in the running of the club! In a sidebar discussion about future program possibilities, there was substantial support for a program to be entitled “The History of Science in the Muslim World.”
Webmaster John Kirszenberg announced that yet another change in the operating system of the U of A’s website had complicated his life once again; but, as we have learned to expect, John managed to conquer the new cyberbestiary — permitting the membership to continue to read the exquisitely-written minutes of the last meeting together with those of the previous 14 years included in the Archives. Thank you, John!
Treasurer Dan Galehouse subsequently advised that, with the advent of spring, our net wealth after dinner expenses for the evening had increased by two dollars to a staggering $75.38. And after our attention was called to an article featured on the cover of the SAMPE Journal, “High Aspect Ratio Sub-Micron and Nano-Scale Metal Filaments,” in which author George Hansen credits his associate, Bill Jenkin, with having invented this patented technology, the club gave Bill a round of applause.
At which point Charlie Wilson introduced our speaker, his friend and former student, Dr. David A Drabold, Professor and Graduate Chair, Department of Physics and Astronomy, Ohio University of Athens, whose topic was Computer Modeling of Complex Materials.
In a spirited, fun lecture, with its really intricate content relieved by really great Power Point graphics, our speaker first softened up the audience by paying what he deemed a “tribute” to several of his ex-UA professors (some of them present in the room!). This he followed with a confessional detailing some of the undergraduate tricks that he and a confederate had played at the time – on the assumption that “the statute of limitations has expired.”
Getting down to business, Dr. Drabold defined a complex material as a system in which we don’t know the structure in microscopic detail, e.g., glass, amorphous materials, polymers, or defects in crystals; and a good model as one that doesn’t conflict with any experiments. To do a reliable simulation on a computer, our speaker explained, one obviously must have a way to work out the forces between the atoms, and the dynamics associated with interatomic interactions. To achieve a reasonable structural model he/(she) needs a coherent way to find x- y-z coordinates that don’t conflict with reality. And, he cautioned, this cannot be achieved by writing down some ad hoc functional form — for, as Dave advised in a singularly quotable quote, “Your intuition may be good, but nature is more subtle.”
The rest of the talk was devoted to methods of achieving objectives like the above — all of which seem to have limitations. These efforts require resorting to quantum mechanics, which could involve the notorious Schrödinger equation – which, labeled “The Terrible Truth,” Dave displayed the screen just to frighten us. “It isn’t too hard to write down,” he claimed, “but it’s almost impossible to solve — a ghastly problem, hopeless for real problems involving lots of atoms, electrons, etc.”
Then, however, came the epiphany: “It can’t be this hard or physics would still be in the Stone Age. There is lots more information contained in these [Schrödinger] wave functions than you really need. What you really care about in practice is the charge density, the electronic charge density, total energy, forces . . . things like that.” There are, it seems, approximations that work. One of these turns out to be the Thomas/Fermi technique. Stated non-mathematically, “You hand me the electron density of the system and I’ll tell you what the energy is.” After one does all the math associated with the quantum mechanics built into energy density theory (involving 20 to 50 thousand lines of Fortran!) one can do computer simulations that really relate to experimental work. One can, for example, “perform accurate dynamic simulations for most of the periodic table, routinely providing structure, electronic spectrum, chemical shifts and other properties.”
The first of two magnificent 3-D animations showed us an enormously-magnified microscopic view of a defect in a silicon lattice, in which we saw a localized vibrational mode of two copper atoms oscillating vertically inside a flexible rectangular crystalline network of hundreds of silicon atoms. We could see directly how the lattice was flexing, which bonds were elongating, and how the bond angles were changing.
But when we got to Dave’s specialty, glasses, we were treated to the piece de resistance of the evening— an animation cell he built from 240 atoms, that was an effort to the answer the question, “How does silver diffuse in germanium-selenium glasses?” In what he entitled “Dance of the Silver Atoms,” we watched enterprising yellow silver atoms slyly sneaking through a squirming mass of red germanium and blue selenium atoms that formed a writhing 3-D geometric cage – inside which additional, silver-colored silver atoms simply lolled about, as reluctant to move as a visiting in-law.
The bottom line turns out to be that Dave and his colleagues have achieved a remarkable coordination between their models and actual motions. But, far from resting on their laurels, they trudge on, pioneering radically different techniques (some employing random number generators) creating new codes with names like “Fireball” and “Reverse Monte Carlo,” with a goal of devising methods that will permit attacking structures as complex as DNA.
As someone said afterward, if our speaker delivers classroom lectures of that quality, there are some very lucky students at Athens. Our thanks to Dave.
AS ALWAYS, WE WELCOME VISITORS.
Jack Gieck
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Newsletter
Meeting Announcement: MONDAY, April 25, 2005 - TANGIER, 6:00 PM
Returning with our gratitude and esteem for our April meeting will be our be our own, much-missed Alan M. Gent, Professor Emeritus of Polymer Physics and Polymer Engineering, at the University of Akron, where he was also Dean of the Graduate School for eight years. An internationally-known consultant on the physics of elastomers, Dr. Gent is eminently qualified to speak about
ELASTIC INSTABILITIES IN RUBBER
Minutes, April 25, 2005
Sixteen members and guests gathered to hear our speaker. Those attending were Alan Gent, Bill Arnold, Ron Eby, Dan Galehouse, Jack Gieck, Bob Hirst, Bill Jenkin and Milian France, John Kirszenberg, Leon Marker, Pad Pillai, Jerry Potts, Darrell Reneker, John Sommer, Ernst von Meerwall, and Charlie Wilson.
In our short brief business meeting Treasurer Dan Galehouse advised that our wealth had increased $17.00 since last month, resulting in a heavy new balance of $92.38 for Treasurer Dan’s strongbox!
Bob Hirst announced that the Sunday Akron Beacon Journal publishes a list of club meetings for the coming week.
Charlie Wilson announced the list of nominees to serve as officers for the coming year as:
| Chairman: | Ernst von Meerwall |
| Vice Chairman: | Darrell Reneker |
| Secretary: | Jack Gieck |
| Asst. Sec: | Jerry Potts |
| Resv. Sec: | Charlie Wilson |
| Treasurer: | Dan Galehouse |
| Program co-Chairs: | Bob Hirst & Sam Fielding-Russell |
| Program vice-Chair | Leon Marker + Volunteers, as solicited by Charlie |
| Webmaster: | John Kirszenberg |
A motion was made by Bill Jenkin to close the nominations and accept the slate of nominees, as read, which motion was seconded by Bob Hirst. Motion carried.
Our speaker for the evening needed no introduction due both to his familiarity as a cherished friend within our group and to his worldwide professional stature. Dr. Alan Gent is a world-renowned polymer scientist with degrees through the Ph.D. from the University of London, coming to Akron University in 1961 where he has served in many positions including Graduate Dean, having earned many honors, including the Mobay Award, Bingham Medal, 3M Award for excellence in teaching science, Charles Goodyear Medal of the Rubber Division, NASA Astronauts Personal Achievement Award (Silver Snoopy), member of National Academy of Engineering, High Polymer Physics Prize, Honorary Ph.D. from two European Universities. He was speaking this evening about Elastic Instability of Rubber.
Dr. Gent began by noting that people typically associate structural instability with the breakage or failure of structural parts. What is unexpected is that an instability can occur without an actual failure when the stiffness of parts decreases to zero, which happens easily in unreinforced rubber parts. Such a part, when extended, responds with an increased tensile force as its extension is increased; however, the rate of force increase decreases as the extension is continually increased until a point is reached that yields no force increase with further extension. In fact, at that point, further increases in deflection may result in decreased tensile force.
Mathematically, this point on the stress-strain curve is described as having zero slope. Physically, it has zero stiffness. If the rubber part were a load-bearing member it could support no further load increases, thus becoming unstable and would deflect without bound. Only if the material were capable of strain-hardening, meaning that the slope of the stress-strain curve again became positive with increased strain, could increased load be borne.
Alan demonstrated several examples of this phenomenon, beginning by inflating a rubber tube — which burst. Analyzing what had happened, he explained that as the inflation pressure increased to a level sufficient to expand the radius of the tube by 60%, a local elastic instability had occurred with rapid radial expansion of a short length of the tube. At that location along the tube, the stress had reached a maximum point on the stress-strain curve with the material experiencing zero stiffness. As that happened the increase in volume of the local bulge allowed the remainder of the tube to decrease in volume, thus decreasing the stress in those areas. Only if the tubing material strain-hardens can the process be prevented from producing a runaway expansion of the bulge, resulting in a burst tube. A similar process occurs, we learned, in an arterial aneurysm.
Inflating a toy balloon, our speaker demonstrated the local bulging-out of one side of the balloon. In fact, he explained, balloons always inflate sideways with one side bulging-out. They do not inflate evenly about the sphere. The non-bulged portion stretches only when the initial bulge strain-hardens and accepts increased stress, thus preventing a blowout.
We saw another type of ballooning in the example of bubbles that can form in rubber specimens surrounded by a high-pressure gas inside an autoclave. Given enough time, the specimens absorb the pressurized gas. Then, if the surrounding pressure is suddenly decreased, gas bubbles can form inside the rubber specimen if the pressure has exceeded the modulus of elasticity of the rubber — which is commonly 2 MPa.
Finally, Alan called our attention to another familiar example of rubber’s elastic instability — the twisting of rubber (band) strands as used to power a model airplane propeller. As all model airplane fans have learned, twisting a stretched rubber band torsionally along its length produces one, then two, then a long series of rubber “knots” along the length of the, now stretched, rubber band. The mechanism occurring, we learned, is most interesting: a local bit of the rubber band has reached its maximum point in the stress-strain curve and begins to stretch at a greater rate than at other places along the length of the rubber band. Also, such stretch is asymmetric so the band deflects sideways, then twists into a knot, locking-in the increased strain and locking-out further strain increases. As the knot forms and local straining occurs, strain actually decreases along the rubber band away from the knotted zone, limiting the tensile force in the band. Further winding will sequentially produce more and more knots with little increase in tensile force in the rubber band. Energy storage has been effected by straining the rubber rather than by increased stress in the rubber. So, the area under the stress-strain curve has increased laterally, rather than vertically. Since rubber can undergo such large deflections before rupture, huge amounts of energy can thus be stored by winding such rubber bands.
Moreover, when the energy is being released back into turning the propeller of a model airplane, it returns as a nearly constant torque during unwinding of the rubber band. There are likely many more examples, all of which must arise from the same root cause, the leveling of the stress-strain curve, so that unbounded deflections occur with increased stress.
Drawing our attention to the most commonplace, homespun phenomena we have all experienced and asking why, our speaker focused our attention on the subtleties of the physics of rubber— a substance most of us claim to be familiar with. One can understand why the mind and persona of Alan Gent has earned a multiplicity of awards.
Jerry Potts & Jack Gieck
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Newsletter
Meeting Announcement: May 23, 2005 - TANGIER, 6:00 PM
Returning as our speaker after more than a dozen years (September, 1992, "Modeling of Polymer Inclusion Complexes" according to the impeccable records kept by our webmaster and secretary) is A. Schulman Professor of Polymer Science and Ohio Eminent Scholar
Wayne L. Mattice, an internationally known physical chemist, an expert on molecular modeling of polymers and the numerical simulation of their kinetics and dynamics. Dr. Mattice's topic this time is:
MISCIBILITY OF CLOSELY RELATED POLYMERIC HYDROCARBONS
Minutes, May 23, 2005
Our last meeting before the summer solstice was attended by Tom and (much missed) Marie Brooker, Alan Gent, Tom Dudek, Bob Erdman, Sam Fielding-Russell, Dan Galehouse, Jack Gieck, Lloyd Goetler, Leon Marker, Jerry Potts, Darrell Reneker, Dick Sharp, Jack Strang, Ernst von Meerwall, and Charlie Wilson.
Chairman Ernst von Meerwall, our reelected leader for yet another year (thank you, Ernst!) began by announcing that he will be hosting yet another luncheon for the club’s Executive Committee at the Martin University Center some time during the summer “lull,” with the objective of planning yet another season of typically empyrean programs. While on the subject, he announced that the speaker for our first meeting in September will be newly-minted U if A Ph.D. Critt Ohlemacher, who, in a scientific way, is Alan Gent’s “grandchild.” Appropriately enough for the Akron Physics Club, Dr. Ohlemacher will be talking about rubber.
Charlie Wilson was invited to advise the club that he had recruited University of Akron biology Professor Randy Mitchell for our October meeting to discuss further evidence turned up in recent years about the reality of evolution. At which point your secretary was tapped to let the club know about what he found some interesting astronomical news: During the month of August the planet Mars will be closer to the earth than it has ever been in recorded history, culminating on August 27th, when it will be at the brightest object in the sky— second only to the moon. Indeed a 75-power telescope will enlarge its 25 arc seconds to the diameter of the moon. And it will be more than a millennium and possibly 60,000 years before the planet gets this close again — by which time, our chairman observed, we will all be retired.
Treasurer Dan Galehouse proclaimed that our treasury had swelled by an entire dollar to the impressive sum of $83.38 — a balance modest enough, however, that he will not require hired security to preserve our cash over the summer. But, before the evening was out, Dan announced that someone had overpaid by ten dollars(!) bringing the total to a $93.38, enlarging his responsibility accordingly.
All of which brought us to Ernst’s presentation of our speaker for the evening, A. Schulman Professor of Polymer Science and Ohio Eminent Scholar Wayne L. Mattice, talked about work he has been doing with regard to the Miscibility of Closely Related Polymeric Hydrocarbons.
Beginning by reminding us of the freshman chemistry axiom that “like dissolves like,” our speaker cited the common example that low molecular weight hydrocarbons are generally miscible with one another (e.g., one need not worry when adding a fill of Shell gasoline to half a tank of BP). But, he pointed out, if we begin stitching these molecules together to make long-chain molecules — polymers — then “the world changes.” But this can’t be because the fundamental physics changes. So what happens to the miscibility of these materials when they have higher molecular weight? This was the subject of his talk.
Put very simply, miscibility is a matter of how readily different molecular structures fit into each other when mixed together. But predicting their behavior in this regard is a challenge .
For one thing, Dr. Mattice explained, with small molecules the entropy of mixing is usually positive because there is a large increase in number of arrangements of the centers of mass of the molecules. But with large molecules, although the same mathematics still applies, the number of distinguishable particles per unit volume becomes much smaller, so there is a smaller advantage in the randomization of the centers of mass. It follows that the free-energy change on mixing is a critical factor in predicting which polymers will readily mix and which ones will seem to abhor one another.
To be able to predict the relative miscibility of large molecules, a mechanism had to be identified that causes these effects to happen — something a number of researchers have been working on for more than a decade. Dr. Mattice’s group has concentrated its attention on isomers of polypropylene — polymers having the same empirical formula but with the atoms arranged in different structural configurations; namely syndiotactic, isotactic, and atactic polypropylene — some pairs of which spontaneously mix, while other combinations “abhor each other.” Their goal was to identify a mechanism responsible for these effects that would be implicit for other polymers. Specifically, their objectives — and the objectives of Dr. Mattice’s talk, were to
1. Describe a simulation that would reproduce what nature does.
2. Identify the mechanism.
3. Once we know the mechanism, is there something that only happens in polypropylene or does it have implications for other known polymers?
That he accomplished all three objectives — and explained them in a teaching style that has earned him multiple awards — was evident in the detailed questions and discussion that followed.
A reminder that not only do WE WELCOME VISITORS, but WE ALSO WELCOME STUDENTS — thanks to our February speaker, Dr. Bill Arnold who has already paid for their dinners!
Jack Gieck
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Newsletter
Meeting Announcement: MONDAY, September 26, 2005 - TANGIER, 6:00 PM
Our first speaker of the new season, a student of Gary Hamed who recently finished his own PhD, has consequently been characterized by Chairman Ernst as being a “grandchild” of Alan Gent — academically speaking, that is. Dr. Crittenden Ohlemacher, who has been serving as Assistant Manager of the Maurice Morton Institute of Polymer Science at the University of Akron will be talking about a subject our club has most recently heard about from Alan himself:
Natural Rubber Compounds
and
Their Counter-Intuitive Behavior
Minutes, September 26, 2005
Members and guests gathered to hear our speaker at the first meeting of 2005-2006 included Bill Arnold, Bill Dunn, Sam Fielding-Russell, Jack Gieck, Lloyd Goettler, Rus Hamm, Bob Hirst, Bill Jenkin and Milian France, Leon Marker, Jerry Potts, Darrell Reneker, Dick Sharp, John Sommer, Jack Strang, Ernst von Meerwall, and Charlie Wilson.
Chairman Ernst von Meerwall opened the meeting by recognizing a visitor, invited by Jack Gieck. Mr. Rus Hamm has a background in Engineering Physics, having graduated from the University of Kansas in 1972 and working in the area of Flash Lamps as applied to the areas of PET Modification and Dermatology Machines. (Moreover, the first test of his extremely bright flashes was so successful it melted the camera!)
Ernst then also recognized that our oldest member, Mr. Bill Jenkin had recently celebrated his 92nd birthday and is still professionally active, giving Bill the floor to explain his recent work. Bill gave a two-minute discourse on the details of Carbonyl Metallurgy, which enthralled everyone, recognizing that retirement is certainly not “The End” of a career. Birthdays are good for you…the more you have, the older you get. And, while one never wants to get old, the older you get, the older you want to get. Way to go, Bill!
Chairman von Meerwall then announced that Bill Arnold had just contributed to APC’s effort to recruit new members from the ranks of Physics Students. Now to attract the Students!
Prior to our short business meeting we had already noticed the absence of our Treasurer Dan Galehouse by the fact that Chairman Ernst von Meerwall required payment of the dinner cost and then gave no financial report during the meeting, which seemed to worry no one!! We look forward to Dan’s presence and Report next time in order to calm our financial angst.
Program Chairman, George Sam Fielding-Russell, outlined the coming programs until Christmas, including: October; Facts of Evolution and November; Advanced Airship Technology. Sam also noted that we need speakers for the Winter/Spring Season and is open to suggestions.
Chairman von Meerwall then introduced our evening Speaker, Dr. Crittenden Ohlemacher, who he calculated to be a grandstudent of Alan Gent, having been a graduate student under Dr. Gary Hamed. Dr. Ohlemacher is currently Assistant Manager of Applied Polymer Research at the Maurice Morton Institute of Polymer Science at the University of Akron . Dr. Crittenden (Crit) also received an MS in Physics from Ohio University and a Masters in Polymer Science from Akron University in 1990.
Crit opened his talk, stating that much of what he had to say reaches back to the 1800’s but has relevance today, and would concentrate in three areas: Natural Rubber, Strain Crystallization with Filler Effects, and Oriented Networks, all of which deal with the phenomenon of crystallization.
Natural Rubber:
This material principally consists of crosslinked molecules of polyisoprene, which may be diagrammatically represented by intersecting tangles of springs, representing the crosslinks connecting nearby molecules.
Straining of the material in a uniaxial direction causes stretching and alignment of the molecular crosslinks with a consequent contraction of the space between molecules to the extent that the material is said to have “crystallized,” similar to the molecular structure of a metal. This process is known as Strain Crystallization, occurs in increasing amounts with increased strain above 20%, and stiffens the material upon occurrence.
Synthetic Rubber also demonstrates such strain crystallization; however, not until a higher level of strain, thought to be due to the lower cis content of the molecules in synthetic rubber compared to natural rubber. Similar crystallization levels can be achieved for both rubber types.
Reinforcing Agents and Fillers:
Introduction of carbon black, and certain other small particles, into natural and synthetic rubber can have the dual effects of increasing both the elastic modulus and the breaking strength. Such effects are dependent upon what particular material is used and the volume fraction of the material compared to rubber.
The increase in strength is thought to occur due to the higher effective strain close to each particle, assuming a higher modulus of elasticity in the filler material. Such a strain increase enhances crystallization, thus increasing the strength, although not until more than 50 parts per hundred of rubber (phr) has been introduced.
The increased strength is most important near a crack tip where the size of the crystallization zone is increased by the carbon black particles and reorients the direction of crack growth from one that is perpendicular to the direction of stress into a pair of cracks, each propagating from near the crack tip along a direction parallel to the direction of stress. This blunts the crack tip and stops crack growth.
Oriented Networks:
It has been found that prestretching materials prior to strength testing can increase the breaking strength. This is accomplished by stretching to, say 400%, relaxing the material for a period of time, and then restretching to break. The increase in strength is thought to occur due to orientation of chains along the direction of stress during prestretch plus some healing of defects that might occur during the relaxation period prior to the strength stretch.
A similar effect has been tried in the form of double networks when a rubber is partially cured, stressed, and finish-cured under stress. That results in a dual network of molecules, some of which were stressed following precure, and others with no prestress having been cured following application of the prestress. Such materials have been found to have generally decreased strength properties compared to single-stress state materials.
This can happen in reverse with unstable crosslinks being broken during stress and reforming while the stress is still imposed on a rubber material and was stated to be the object of study relative to the Firestone tire recall in the year 2000, with belt separations and crack growth being the stated problem.
The last point came during the Q&A following Crit’s presentation in response to a question by Jack Gieck, which was along the vein of “This is all very interesting from a physics perspective, but for those of us who used to design mechanical rubber parts like engine mountings, ‘Why do we care?’ “ Crit’s answer served to jab the group in the side and remind us that Physics does have application after all.
Jerry Potts and Jack Gieck
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Newsletter
Meeting Announcement: MONDAY, October 24, 2005 - TANGIER, 6:00 PM
Our speaker for October is one who has long been anticipated, because his subject has been such a hot topic for lo these many months in news magazines and on editorial pages. Dr. Randall Mitchell, Professor of Biology at the University of Akron will be talking about
THE FACTS OF EVOLUTION
Minutes, October 24, 2005
With an attendance that may be a club record, members and guests gathered to hear our much-anticipated speaker included Bill Arnold, Tom and Marie Brooker, Dave Brown, Sam Fielding-Russell, Dave Fielder, Milian France, Dan Galehouse, Jack Gieck, Rus Hamm, Bob Hirst, Bill Jenkin, Steve Kraus, Leon Marker, Pad Pillai, Jerry Potts and his guest M. K. Dash, Dick Sharp and his wife Evelyn, Ernst von Meerwall, Joe Walter, Charlie Wilson, Wiley Youngs, and student guest Richard Deneen — who, together with other guests, were welcomed by Chairman Ernst von Meerwall.
In our usual incredibly brief business meeting, Chairman Ernst called on Treasurer Dan Galehouse, who (after having lamented the increase in our dinner cost to $17), reported his regret that, because of the heavy attendance, our balance had nonetheless grown from $77.38 to a staggering $85.38, plus $133 in our unspent student meal fund — prompting our chairman to apologize to Bill Arnold for not spending his money more rapidly.
Which brought us to an outstanding report by program cochairman Sam Fielding-Russell, who announced that our November program would feature a return of Charles Lavan of Lockheed Martin, who will give us An “Update on Advanced Airship Technology;” our January speaker, Dr. Harvey Rosenthal of the University of Akron, will speak on “Science in the Golden Age of Islam;” to be followed by Dr. Klaus Fritsch of John Carroll University, whose topic will be “The Physics of Flying.” And since the October meeting we’ve learned that two more speakers have been signed up: Dr Martin Sentmanat, whose field is rheology, and Prof. Mark Foster, who will speak on the ethics of science. It’s obviously going to be a good year (words we were not permitted to utter at Firestone).
Called upon by Chairman Ernst, Charlie Wilson introduced our speaker, citing an impressive list of accolades earned by Dr. Randall Mitchell, Professor of Biology at the University of Akron . Accompanied by great (digital) graphics, custom-produced for his presentation, our speaker kept his audience spellbound for more than an hour as he explained The Facts of Evolution with what became infectious enthusiasm. Dr. Mitchell slid into his topic by reminding us that as physicists we have it pretty easy — with only a hundred or so elements — and not even that many subatomic particles — while biologists have more than 10,000 different species to contend with (and lots of species within species)!
Evolution, Dr. Mitchell declared, is the lynchpin of biology. Despite the popular confusion about the meaning of the word today (e.g., that people are descended from apes!), evolution is really about some very simple things. not nearly as theologically challenging as many people think. Evolution says simply that we see a lot of evidence that all living things (people, bugs, flowers, bacteria) are descended from one, or maybe a couple of ancestors. In fact, it was generally accepted by scientists in Darwin ’s time, 150 years ago, that all creatures are related. Darwin just defined how it happened.
Crediting Charlie Wilson with changing the course of a presentation that might have been an academic diatribe against the nay sayers, Randy told us instead what we know, and why we know it. So, rather than talk about his particular area of research, he proceeded to walk us through a couple of generalized examples of evolution before focusing on some “particularly jazzy examples that show how the application of good old fashioned science to a topic that’s got a lot of challenges” can result in a unified body of knowledge about a subject as complex as the enormous variety of living things.
After citing oddities like birds whose ancestors flew, but who have since learned to swim, and reptiles who similarly found their way into the water over millions of years, our speaker focused his presentation on whales, those strange, enormous creatures that, as he proceeded to demonstrate, had once been terrestrial, hoofed mammals — as he proceeded to uncover clues that have since been covered up. He began the trail with stunning pictures of whale embryos at different stages of development. One of these was that of a dolphin (a species of whale) in which, he pointed out, “we can see the head, we can see the tail, we can see the hind leg. We go back two weeks later, it’s gone!” And “when we look at the front flippers we see fingers. Fingers?” And so it went as the embryo developed before us.
Randy showed us some of the ancient ancestors of modern whales, creatures like the andrewsarchus, which had hoofs, but carnivore teeth; the basilosarchus, a very common ocean dweller who lived 3.5 million years ago that biologists thought was a variety of sea serpent until the 1950s. We were subsequently introduced to the pakiscetus and the ambulocetus — a walking whale!
Fifty million-year-old skeletal remnants of creatures like these were found in the mountains of Pakistan . Our speaker reminded us that the Himalayan mountain ranges of Pakistan and Kashmir had been pushed up from beneath the sea when the drifting tectonic plate of India slowly slammed into the bottom of the Asian continent. It has been, we learned, not unusual to find fossils of ancient sea creatures in other mountain ranges for similar reasons. Moreover, it has been possible to identify the habitat of these ancient creatures (deep ocean vs. fresh water or terrestrial) from the proportion of heavy isotopes of oxygen in their remains. (The ocean inhabitants have a preponderance of the heavier oxygen.)
We beheld intermediate changes in whales’ ancestors, as their ears changed radically, adapting to become devices for detecting low frequencies under water; and we watched nostrils move to the top of the head — changes that were examples of multiple lines leading to the same conclusion, e.g., that hippos and whales are not only distantly related; they are both artiodactyls. “There are lots of questions having to do with evolutionary biology,” our speaker stated, “but they are questions of detail, not of whether.”
Turning to the roles of random mutations versus natural selection, Randy made it clear that the two are not at odds. Rather both elements are required for evolution to occur: 1) variety and 2) natural selection. Variety produces the candidates for natural selection, which acts as a natural sieve that lets through only certain types of genetic variation: those that help the organism survive (indeed succeed) in its environment. He cited such diverse examples as that a flower’s size will exactly match the proboscis of the insect that pollinates it; and that taking an antibiotic will kill the bacteria causing the symptoms, but it lets through the bugs that are not as affected by the antibiotic. And if they are permitted to survive, their children will too. So if they are not all killed (e.g., when we fail to take all of a prescribed antibiotic), we breed a strain of bacteria that are unaffected by a given antibiotic. Related to this kind of scenario, it turns out, is the fact that sickle cell disease is a legacy of having built a resistance to malaria.
Randy summed up his major points: First, belief in evolution is not relevant. Evidence is. Evolution, he postulated, is a unifying principle in science. If you are going to disagree with evolution, you are going to disagree with everything else in the science curriculum, including chemistry, how elements decay, how reality proceeds. Evolution is not an explanation for the origin of life, he cautioned, or of consciousness — although these are legitimate scientific areas for research.
Finally, our speaker offered some advice with regard to our discussing the subject of evolution with others:
“Know the audience. Most people don’t understand what evolution is. Some people are of a mind to believe that the theological consequences of accepting evolution are eternal, and terrible. The stakes are thus as high as they can possibly get and you’re trying to get them to accept your ideas on the subject because of some fossil bones you found somewhere!”
“Most important, use science to teach science.”
“And get rid of politics on the subject. Evolution is not a partisan matter.”
That his talk was both convincing and stimulating became apparent as a profusion of questions and answers and discussion followed — discussion that might have gone on until midnight if Charlie hadn’t closed the curtain half an hour later.
WE WELCOME VISITORS
Jack Gieck and Jerry Potts
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Newsletter
Meeting Announcement: MONDAY, November 28, 2005 - TANGIER, 6:00 PM
Two years ago, then Engineer-Principal and Lead Scientist for Lockheed Martin, Charles Lavan spoke to the club about The Future of Airships. A week later, his company was awarded a $40 million contract by the Missile Defense Agency for a stationary unmanned airship some 500 feet in length that would operate on solar power at an altitude of 70,000 feet. We’re delighted to announce that by popular demand Mr. Lavan, now a Lockheed Martin Fellow, will give us
AN UPDATE ON ADVANCED AIRSHIP TECHNOLOGY
A reminder that not only do WE WELCOME VISITORS, but DINNERS FOR STUDENTS ARE FREE, thanks to Bill Arnold’s fund generosity. Click on Charlie’s e-address, above, to assure your reservation.
Minutes, November 28, 2005
With what probably was record attendance for the Akron Physics Club, members and guests gathered to hear a much-anticipated speaker at the last meeting of 2005 included Bill Arnold, Tom Brooker, Dave Brown, Bill Dunn – and his guest Rick Houck, Dave Fielder, Sam Fielding-Russell, Milian France, Dan Galehouse, Jack Gieck – and his guest Art Hirtreiter, Larry and Barbara Gray, Bob Hirst, John Kirszenberg, Leon Marker, Jerry Potts – and his guest and new associate Mr. Jeong In-hee of Korea, Darrell Reneker, Dick Sharp, Ernst von Meerwall, Joe Walter – and his guest Brit Rinehart, Dave Wertz (of the Lighter than Air Society), Charlie Wilson, and Wiley Youngs.
Called upon by Chairman Ernst von Meerwall, Treasurer Dan Galehouse presented the most protracted financial report of his career, which began with an opening balance of $85.38, less expenses for name tag materials — which expenditure was reduced by a contribution of one cent by our Princess of Name Tags, Milian France (because there wasn’t sufficient petty change in the treasurers’ strongbox) — and was furthered by a ten dollar profit on meal payments (of $500.60) due to the popularity of our speaker — netting a balance of $68.60 — plus $133.00 remaining in the student dinner fund, for a total treasury balance of $201.60. It isn’t often that a treasurer’s report receives (or deserves) laughs. But that’s our treasurer.
At which point Program Co-Chair Sam Fielding-Russell was invited to announce the speakers he we have in store for the remainder of our 2005-2006 year, beginning with Dr. Harvey Rosenthal in January. In February we will have Dr. Klaus Fritsch of John Carroll University ; who will be speaking on “The Physics of Flying;” and in March Dr. Martin Sentmanat (who heads his own instrument company in Akron ) will be talking about rheology. In April Dr. Mark Foster, Professor of the University of Akron ’s Department of Polymer Science, will be speaking on “The Ethics of Science” — which is also the title of a course he and the head of the University’s Philosophy Department are teaching at the university Great schedule, Sam!
Whereupon your secretary was invited to introduce the speaker for the evening, Lockheed Martin Fellow Charles Lavan, Chief Scientist for LM’s High Altitude Airship [as well as its Radar Systems], plans for which he introduced us to two years ago, and for which the Government was then currently issuing a contract to design — making it appropriate for him now to give us An Update on Advanced Airship Technology. For our speaker, it had been a day that began in St. Catherines , Ontario , with his arriving home just in time to leave for our meeting — a schedule that is not atypical for Charles Lavan.
With magnificent Power Point graphics (with good reason — they had been produced for a recent Pentagon briefing on the subject), our speaker pointed out that when his company first started working on the concept in 1998 (in cooperation with General James Abramson, first head of the Strategic Defense Commission), many people thought the idea of an autonomous, pilot less, high altitude airship that would stay up for a year(!) was an absurd idea. But today, Charles observed, the concept has many fathers — especially since there are now eight different countries involved with building, designing and researching such long-endurance airships, for applications that include radio telescopes, radar surveillance platforms (including some to be used for use in drug interdiction), and other applications. Countries that are currently most active are Korea , Japan , and the entire European Space Agency. Even the cluster of islands that constitute Indonesia is actively working on the concept for cellular telephone infrastructures to improve communication in that scattered country.
And there are perhaps a hundred companies in the United States interested in the technology. Much of this work is being privately funded, e.g., a vehicle that a Norton, Ohio , company hopes to launch to an altitude of 45,000 ft. (Lavan’s group did some basic physics calculations on the aircraft, however, which revealed that, as presently designed, the craft could probably rise to an altitude of about ten feet.) Archimedes, Charles observed, must be turning over in his grave!
Lockheed Martin is currently building two vehicles (in addition to the 56,000 cu ft stationary blimps currently in service over Baghdad , as well as new Goodyear blimps). The other high altitude vehicle, “ ISIS ” is being built by Lockheed Palmdale. The final version of the Akron ship will be 500 ft long with a volume of 3.7 million cu ft (the volume of a Goodyear blimp, for reference, is about 200,000 cu ft.) and it will be designed to stay up for a year at 70,000 ft
The initial prototype to be built here in Akron will be 430 ft long with a volume of 420,000 cu ft. It will be designed to operate at 60,000 ft and to stay up there, operating under autonomous control, for 30 days at a time (although there is nothing to indicate that it couldn’t stay up for a year). The craft will be built in the old Goodyear Airdock, which will be subjected to a $30 million renovation to be able to contain it. And it will be big! It will be taller than either the Akron or the Macon . The four rotors, at 25 ft in diameter, will be the size of windmills. They will be powered entirely by a solar array half an acre in area, which will generate 100 kilowatts of power (using amorphous silicon solar cells), permitting the aircraft to operate continuously at 25 knots, with a top speed of 60 to 70 knots. In addition to powering the craft, the solar panel will charge lithium-polymer batteries during the day, and these will provide power for operation at night. Control will be entirely by the rotors, since barometric pressure at 60,000 feet is only one twentieth of that at sea level — at which air density controllable tail fins would be impotent.
Payload capacity will be 500 to 1300 lb, depending on the integrity of the envelope. Payload is very sensitive to altitude — five times as much payload can be carried at 59,000 feet than at 70,000 ft. The high altitude airship will have the familiar cigar shape, the optimum shape for reducing the coefficient of drag (a spherical shape, for example, would have ten times as much drag). Propulsive power, it turns out, is a cubic function of velocity. The dynamics of flight are similar to those of a submarine. There are subtle, counterintuitive aerodynamic effects, e.g., something called “virtual mass,” which is created by entrained air, making the vehicle operate much more sluggishly than might be expected, and sapping propulsive power. But aerodynamics is not the reason for its slanted, X-shaped tail fins. It’s just that the vertical fin of +-shaped fins will not clear the ceiling of the Airdock!
The vehicle will operate above the troposphere (50-60,000 ft), at which altitude the temperature not longer stops decreasing, but begins incrementally increasing, providing a region relatively free from updrafts and eddies. But one of the hazards at that these very high altitudes, particularly in the vicinity of volcanoes (of which there are about 2000 in Alaska ) is upward-traveling lightning.
There were lots of questions, including one about the possibility of using hydrogen for increased buoyancy. Charles pointed out that hydrogen, being a diatomic molecule has only about 15% greater lift than monatomic helium. Nevertheless although the Hindenburg disaster has obviated any serious consideration of launching the craft with hydrogen, once at altitude, replenishment of leaking gas could be done with hydrogen generated by the hydrolysis of on-board water.
When the prototype is launched here in Akron (late in 2008), it will rise at about 1000 ft per minute, taking about an hour reach 60,000 feet, at which altitude it will head west under ground control, probably to White Sands, New Mexico for its 30 days of initial testing. Once there, it will be capable of maintaining its position autonomously within 2 km.
When it returns to Akron , it will take 5-6 hours to come down, beginning in Chicago — no doubt giving aircraft controllers in the Midwest an additional shot of adrenaline as it makes its way home. And it will be a great day for Akron — second only to the successful launch.
Jack Gieck