On the binding of nanometric hydrogen–helium clusters in tungsten

In this work we developed an embedded atom method potential for large scale atomistic simulations in the ternary tungsten–hydrogen–helium (W–H–He) system, focusing on applications in the fusion research domain. Following available ab initio data, the potential reproduces key interactions between H, He and point defects in W and utilizes the most recent potential for matrix W. The potential is applied to assess the thermal stability of various H–He complexes of sizes too large for ab initio techniques. The results show that the dissociation of H–He clusters stabilized by vacancies will occur primarily by emission of hydrogen atoms and then by break-up of V–He complexes, indicating that H–He interaction does influence the release of hydroge

Sampling in the multicanonical ensemble: Small He clusters in W

We carry out generalized-ensemble molecular dynamics simulations of the formation of small Helium (He) clusters in bulk Tungsten (W), a process of practical relevance for fusion energy production. We calculate formation free energies of small Helium clusters at temperatures up to the melting point of W, encompassing the whole range of interest for fusion-energy production. From this, parameters like cluster break-up or formation rates can be calculated, which help to refine models of microstructure evolution in He-irradiated Tungsten.Comment: 27th Annual CSP Workshop on Recent Developments in Computer Simulation Studies in Condensed Matter Physics, Athens, GA, 201

MS-220: Homer W. Schweppe Papers

This collection is made up of a vast variety of materials pertaining to Homer William Schweppe’s experiences during World War II. Schweppe compiled various items during his initial military service in the United States, such as his Seattle Port Officer I.D. badge and his uniform patches. There are also items from his time at Camp Ritchie, including his glossary of “Nazi Deutsch” terms and a book on the Order of Battle of the German Army, to which he contributed. Schweppe also included items he collected while overseas, such as a German Map of the D-Day Invasion area, a welcome pamphlet from Stratford-Upon-Avon in England, the signatures of both Hitler and Himmler, Russian Identification cards, and multiple military medals. He also kept a collection of German letters and other paraphernalia related to the German P.O.W.s at Camp Ritchie following the war’s conclusion. There is some uncertainty of what Schweppe did specifically once he went to Europe, but his collection certainly gives an indication to where he was. Special Collections and College Archives Finding Aids are discovery tools used to describe and provide access to our holdings. Finding aids include historical and biographical information about each collection in addition to inventories of their content. More information about our collections can be found on our website http://www.gettysburg.edu/special_collections/collections/.https://cupola.gettysburg.edu/findingaidsall/1188/thumbnail.jp

An Interview With Albert W. Tucker

The mathematical career of Albert W. Tucker, Professor Emeritus at Princeton University, spans more than 50 years. Best known today for his work in mathematical programming and the theory of games (e.g., the Kuhn-Tucker theorem, Tucker tableaux, and the Prisoner\u27s Dilemma), he was also in his earlier years prominent in topology. Outstanding teacher, administrator and leader, he has been President of the MAA, Chairman of the Princeton Mathematics Department, and course instructor, thesis advisor or general mentor to scores of active mathematicians. He is also known for his views on mathematics education and the proper interplay between teaching and research. Tucker took an active interest in this interview, helping with both the planning and the editing. The interviewer, Professor Maurer, received his Ph.D. under Tucker in 1972 and teaches at Swarthmore College

Elements with finite Coxeter part in an affine Weyl group

Let $W_a$ be an affine Weyl group and $\eta:W_a\longrightarrow W_0$ be the natural projection to the corresponding finite Weyl group. We say that $w\in W_a$ has finite Coxeter part if $\eta(w)$ is conjugate to a Coxeter element of $W_0$. The elements with finite Coxeter part is a union of conjugacy classes of $W_a$. We show that for each conjugacy class $\mathcal{O}$ of $W_a$ with finite Coxeter part there exits a unique maximal proper parabolic subgroup $W_J$ of $W_a$, such that the set of minimal length elements in $\mathcal{O}$ is exactly the set of Coxeter elements in $W_J$. Similar results hold for twisted conjugacy classes.Comment: 9 page