Back Of Envelope Research Articles

Fly by Night Physics: How Physicists Use the Backs of Envelopes

Fly by Night Physics: How Physicists Use the Backs of Envelopes

Carlotta Speaks: The Letters of Carlotta Monterey O'Neill to Gene Baker McComas, 1918–1952

Carlotta Speaks: The Letters of Carlotta Monterey O'Neill to Gene Baker McComas, 1918–1952

Evolution of the International Security Environment

I have to start with a confession, distinguished Commandant, Generals, Excellencies, ladies and gentlemen. This is my first speech for a long time. So I am a little bit rusty. The reason is that I retired from public speaking last year. I was in London, giving a talk next to the Houses of Parliament. When I finished, a man in the audience, who looked like the American detective Colombo, you remember with the hand woven hat and dirty raincoat, came up on to the stage and said ‘—Dr.Shea, Thank you very much for coming this evening, take this envelope, this is a small token of our appreciation.’ I looked inside the envelope, and I saw a bundle of money. But I immediately thought: W e live in the age of Facebook, Instagram, the social media, nothing can be secret any longer, right? S o I decided to hand the envelope back. And when I did so, a tear went down his face. And he said ‘—Ooh, Dr.Shea, thank you so much for giving this money back. Next time we will use it to get a really good speaker!’. S o I decided immediately to retire. But then the Commandant approached me, and Turkish hospitality is legendary, which I’ve just verified again. So thank you very much, Commandant, for the kind hospitality, I’ve made an exception for you. Here I am, as they say in the music business, ‘one night only’ , to talk to you today.

John Gordon King

John Gordon King

Optimal Betting Under Parameter Uncertainty: Improving the Kelly Criterion

The Kelly betting criterion ignores uncertainty in the probability of winning the bet and uses an estimated probability. In general, such replacement of population parameters by sample estimates gives poorer out-of-sample than in-sample performance. We show that to improve out-of-sample performance the size of the bet should be shrunk in the presence of this parameter uncertainty, and compare some estimates of the shrinkage factor. From a simulation study and from an analysis of some tennis betting data we show that the shrunken Kelly approaches developed here offer an improvement over the “raw” Kelly criterion. One approximate estimate of the shrinkage factor gives a “back of envelope” correction to the Kelly criterion that could easily be used by bettors. We also study bet shrinkage and swelling for general risk-averse utility functions and discuss the general implications of such results for decision theory.

Sketchy Tweets: Ten Minute Conjectures in Graph Theory

Following this advice, we should look over the big questions, then doodle and sketch out some approaches. If you are an expert, then this is easy to do, but most people do not want to wait to become an expert before looking at interesting problems. Graph theory, our area of expertise, has many hard-to-solve questions. Some hark back to the recreational roots of the area yet still keep their mystery. These ‘‘acorns’’ can be planted on the backs of envelopes, on a blackboard, and over a coffee. Our goal is to collect some of these conjectures—arguably some of the most intriguing—in one place. We present ten conjectures in graph theory, and you can read about each one in at most ten minutes. As we live in the era of Twitter, all the conjectures we state are 140 characters or fewer (so ‘‘minute’’ here has a double meaning). We might even call these sketchy tweets, as we present examples for each conjecture that you can doodle on as you read. Hamming also references ambiguity: good researchers can work both on proving and disproving the same statement, so we approach the conjectures with an open mind. He also mentions that a good approach is to reframe the problem, and change the point of view. One example from Vizing’s Conjecture (which is discussed as our second-to-last conjecture in the following text), is the three-page paper [2] which, with a new way of thinking, reduced most of the published work of twenty years to a corollary of its main result! Given the size of modern graph theory, with its many smaller subfields (such as structural graph theory, random graphs, topological graph theory, graph algorithms, spectral graph theory, graph minors, and graph homomorphisms, to name a few), it would be impossible to list all, or even the bulk of the conjectures in the field. We are content instead to focus on a few family jewels, which have an intrinsic beauty and have provided some challenges for graph-theorists for at least two decades. There is something for everyone here, from undergraduate students taking their first course in graph theory, to seasoned researchers in the field. For additional reading on problems and conjectures in graph theory and other fields, see the Open Problem Garden maintained by IRMACS at Simon Fraser University [24]. We consider only finite and undirected graphs, with no multiple edges or loops (unless otherwise stated). We assume the reader has some basic familiarity with graphs and their terminology, including notions such as cycles, paths, complete graphs, complete bipartite graphs, vertex degrees, and connected graphs. We use the notation Cn for the cycle with n vertices, Pn for the path with n vertices, and Kn for the complete graph with n vertices. The complete bipartite graph with m and n vertices of the respective colors is denoted by Km,n. All the background we need can be found in any text in graph theory, such as those of Diestel [9] and West [41], or online (see for example [42]).

Preface to the Article “Inorganic Energetics from Mainframe to ‘back of envelope'” by H. Donald B. Jenkins

Preface to the Article “Inorganic Energetics from Mainframe to ‘back of envelope'” by H. Donald B. Jenkins

London was ours: diaries and memoirs of the London Blitz

was ours from the hour the blacked-out night hid its beauty until the morning siren signalled the coming day. - Joan Bright Astley. The German bombing raids on London from September 1940 to May 1941 - the London Blitz - supply us with some of the most dramatic and mythologised stories from the Home Front of the Second World War. But often overlooked in historical studies of the Blitz are the narratives supplied by Londoners themselves. In shelters, in kitchens and in offices, they wrote about their daily lives under duress, scribbling into diaries, notebooks and on the backs of envelopes. was Ours analyses over two hundred letters, diaries and memoirs written by those citizens who endured the Blitz, restoring the forgotten voices of ordinary individuals to the collective memory of the Blitz and World War II. Their writings reveal widely varying points of view, often at odds with official wartime narratives and subsequent histories, making this a vital contribution to the social history of wartime Britain.

Dynamic safety of active trailer steering systems

The dynamic safety of an active steering system for an articulated heavy goods vehicle is investigated. The vehicle is a tractor semi-trailer with two independently steerable axles on the trailer. Several different vehicle dynamics modelling approaches are used to investigate the aspects of the safety of the steering system. These include ‘back of envelope’ calculations, a single degree-of-freedom yaw model, a simplified yaw-plane model using Matlab SimMechanics, with realistic controller frequency response assumptions, and a complex multi-body model of the whole vehicle using TruckSim. Specific safety issues of concern associated with the primary active steering function are: (a) the necessary actuation bandwidth for stable response at high speeds, and (b) the performance implications of disturbance rejection requirements, e.g. side winds and split friction braking. It is found that vehicle tracking improves with increased bandwidth up to 8.3 Hz, but beyond this, performance is limited by other factors. Also, the steering system is able to reject off-tracking disturbances from side winds and split-friction braking, although the latter has a small effect. Additional ‘failsafe’ issues of concern are: (a) whether an independent centring system is necessary on each steerable axle or whether failure of an axle can be safely managed by steering the remaining axles in opposition, (b) the force levels needed in the automatic safety centring system, and (c) the maximum slew rate for centring the axles in an emergency. It is found that individual centring systems for each axle are necessary because axle ‘opposition’ is not a safe strategy for a trailer with two steered axles. The steering actuator is required to generate 32 kN during all modes of operation in order to maintain safety during the specified manoeuvre. A maximum steering slew rate of 11°/s is found to limit additional lateral acceleration to less than 0.2 g.

An Odd Couple?: A First Glance at Chesterton and Newman

I. Introduction Why are Chesterton and Newman so linked in the minds of people who know anything about either of the two figures? On the surface, a few similarities are obvious. Both came from what might be called middle-class families. two seemed natural leaders, even as children--Newman forming his Spy Club and Chesterton, with E. C. Bentley, the famous Junior Debating Club. They were also omnivorous readers who devoured much of the classics. Though Newman's tutors claimed Newman was only a moderately good classicist, he was later regarded as quite a skilled composer of Latin. Similarly, though Chesterton's study of Latin under the famous A. E. Housman ended at the suggestion of none other than Housman, Chesterton's friend, that wild Dominican distributist, Fr. Vincent McNabb, would compare him to Thomas More: the two men, said McNabb, were cockneys whose lack of technical knowledge of the classical languages was more than made up for by an instinctual knowledge of what the words should mean. (1) Both Chesterton and Newman were Englishmen to the core who, nevertheless, found in the Roman Catholic Church--to the dismay and horror of many an Englishman--the pillar and foundation of the truth spoken of by St. Paul in his first letter to Timothy. Neither were the two shy about writing controversially about religion either before or after their voyages across the Tiber. Both also excelled in a variety of fields not limited to religious controversy. Much of Newman's poetry is still well regarded, his Dream of Gerontius likely to live on forever, not least in the musical setting given it by Edward Elgar. His hymn Lead kindly, light seems similarly enshrined both in the literary canons and the hymnbooks. Chesterton's poetry, still being discovered in scribbles on the backs of envelopes or published in obscure newspapers and journals, also has its gems. In an interview late in his career, Graham Greene, upon being asked what poetry he read, responded that he still went back again and again to The Ballad of the White Horse.. (2) And of course, Newman and Chesterton both found only a modest success as novelists. But any list of their similarities is nearly overwhelmed by the flood of differences that one encounters in a first look. They seem truly an odd couple. Chesterton was manifestly fat. driver responsible for him when he lived in South Bend, Indiana, and lectured at Notre Dame in 1930 recalled later that he thought Chesterton nearer to four hundred pounds than three hundred. Newman was thin. Chesterton went to a trade school and entered the world of journalism and publishing. Newman was an Oxonian quite comfortable in the common room of Oriel College. Though neither Chesterton nor Newman had any offspring, Chesterton was a married layman while Newman was a celibate cleric. In fact, Newman recorded that from the age of seventeen he was convinced that his own particular vocation would demand freedom from the demands of a wife and family, however much they were attractive to him. (3) Like that earlier Oxford reformer John Wesley, Newman encouraged many of his own friends to remain single--and sometimes showed disappointment when they did not. Chesterton, on the other hand, included in his youthful notebook lines containing his hopes for a young boy: Sunlight in a child's hair It is like the kiss of Christ upon all children I blessed the child: and hoped the blessing would go with him And never leave him; And turn first into a toy, and then into a game And then into a friend. And as he grew up, into friends And then into a woman. (4) Newman played the violin well and had a mind for music and mathematics. Chesterton loved to sing or hum, but his friends could rarely detect any actual tune in the mix. And his habits with money seem to reveal a sort of pure ignorance about mathematics. Newman was the consummate Victorian correspondent whose letters and diaries would fill thirty-one volumes. …

Differential Geometrical Performance and Poiesis

Conventionally, we construe mathematics as knowledge, and the mathematical sign as representation of knowledge. In this essay I propose an alternative approach, pairing mathematical practice as performance with mathematical writing as technology of performance. This foregrounds mathematics as a poietic rather than a tautological practice, and to interpret this poietic practice I outline a materialist phenomenology. I argue that particular attention to differential geometers’ practices of diagramming or sketching shapes, manipulating algebra, estimating analytic functions, or tracing kinetic processes offers us a chance to grasp how mathematical signs function outside speech yet in a thoroughly material way. What seems fruitful is to treat these practices not as recording or encoding mathematical entities, but as generating them. In other words, I treat mathematical writing not as a technology of representation but as a technology of embodied performance. Moreover, by looking at differential geometrical writing as a performance practice, I offer some examples of how finite gestures enact smooth (“infinitely differentiable”), “abstract,” “objective,” or infinite entities via finite traces. By recognizing that geometers exteriorize and materialize their imagination in common technologies of mathematical writing such as the backs of envelopes or chalk and chalkboard, we can avoid the problem of intersubjective communication. Shared and therefore objective mathematical entities are constituted in the interaction of geometers, their disciplinary logics, and technologies.

Microcomputers and Backs of Envelopes

Microcomputers and Backs of Envelopes

“I Write These Messages That Come”

Thoughts come to my mind at any point, anywhere—I could be on the subway—and if I am alert enough and I have a pencil and paper, I write these messages that come. It might be just a thought, like a statement about something, an insight, or it could be a line of dialog. It could be something that someone says in my head.I have a box filled with these scribbles. Some of them are on paper napkins or the backs of envelopes. These things are often the beginning of a play. Most of the lyrics of the songs that I write are based on these notes—as opposed to a play, which, once it starts, I make. I usually gather a number of those things that have some relation—again, I do not even know why I consider that they are related—and I put them together.

Custer in ’76: Walter Camp’s Notes on the Custer Fight ed. by Kenneth Hammer

Japanese woman) as protagonist, goes on too long, repeating the same sexual imagery. Still — it is a charming book. L. L. LEE, Western Washington State College 266 Western American Literature Custer in ’76: Walter Camp’s Notes on the Custer Fight. Edited by Kenneth Hammer. (Provo, Utah: Brigham Young University Press, 1976. xiii -f303 pages, $10.95.) Americans continue to be fascinated with books about Custer and the saga of the western Indians, if the volume of such publications is a reliable indicator. Custer in ’76 is different from most in that it is a primary source book filled with interviews of many of the participants in the Battle of the Little Bighorn. It is a work of beauty with its fine photographs and clearly illustrated maps. Walter Camp, a civil engineer and railroad magazine editor, had hoped to write a history of Custer’s battle with the Sioux but, unfortunately, he died in 1925 before he could fulfill his dream. Prior to his death, Camp interviewed over two hundred survivors of the battle and scribbled their responses on cards and on backs of envelopes. He left this large collec­ tion of materials to his widow and in 1972 Brigham Young University officials obtained them for their library. The editor of Camp’s notes, Kenneth Hammer, has included material on various aspects of the Sioux battle of 1876. There are lists of Medal of Honor winners from the Little Bighorn battle, muster rolls of the 7th Cav­ alry, and names of Indian scouts and Indians who lost their lives in the battle. Hammer also included biographical material on Walter Camp and a speech he gave for the members of the Order of Indian Wars of the United States. The heart of the book concerns the interviews with 7th Cavalry officers and men, Indian scouts who served the army, Indians who fought against Custer, and miscellaneous people who were involved in some other capacity. These interviews, taken by this early practitioner of oral history, make a fine source collection for research scholars. It relates where people were during the battle and actions they took. Some interviewees expressed their feelings about key people in the battle or suggested how one officer felt about another officer. In general one receives a rather positive view of Custer. At the close of the book Camp gave a lengthy discussion concerning the orders that General Alfred Terry, Custer’s superior, gave to the Colonel before they split forces and Custer rode to his death. The author feels that Terry gave Custer the necessary flexibility he needed in his orders and that Reviews 267 Custer conducted himself properly in pushing the attack against the Indians. It would appear that Camp was rather one-sided in this evaluation and generally indicates his bias in favor of Custer. For researchers this book is a welcome addition to the several other source books on the battle now available (Graham — The Custer Myth and Overfield — Official Documents of the Little Bighorn). Although it is a book that will have limited appeal to a general audience, it will be greatly appre­ ciated by western buffs and Custer scholars. JOHN W. BAILEY, Carthage College Even Cowgirls Get the Blues. By Tom Robbins. (Boston: Houghton Mifflin Company, 1976. 365 pages, $10.95 cloth; $4.95 paper.) Imagine Ken Kesey writing a novel to proclaim he is not a sexist; add the playfulness, the literary self-consciousness, and the philosophizing of John Barth; reduce cynicism and difficulty to the level of Richard Brautigan. And the result would be something akin to Even Cowgirls Get the Blues, a book which (like the author’s first novel, Another Roadside Attraction) seems geared for instant popularity. Tom Robbins comes out valiantly on the right side of many simple issues. He is in favor of women and whooping cranes, freedom and individuality, poetry and magic and humor and sex. He is opposed to vaginal deodorants, and is therefore in favor of the revolution which occurs on the Rubber Rose — a beauty ranch dedicated originally to internal cleanliness, and afterwards to the liberation of its cowgirl staff. Somewhat more idiosyncratically, he is opposed to the chauvinism of the Brain. The...

SI Units applied to aircraft performance calculations

The advent of SI units makes it necessary to revise many standard constants and numerical values which are familiar to a generation of aeronautical engineers whose education and practical experience have been solely with the British system of units.Most affected by these changes are not so much those who spend all their time carrying out (computer-aided) calculations, but those who direct such work and whose personal calculations are limited to the backs of envelopes. The task, for the latter, of assessing and communicating data presented in unfamiliar units is very daunting, and the possibility, for them, of ever being able to think in the new units may seem remote.