Optimal surface cutting

Surface cutting problems in two dimensions are considered for nonrectangular items. An exact solution method is discussed. Outlines of several possible heuristic algorithms are also presented. For the heuristic methods a first approximation to the optimal solution is obtained by encompassing each item by a rectangle and then using some available strategy for this standard problem. Different approaches are then suggested for more accurate methods

From Meal to Mission

(Excerpt) When it comes to introductions, I remember that when I was young and charming and about to go off to Saint Joseph\u27s Prep in Philadelphia (where I was reared and raised), I was somewhat intimidated. I was so because I was about to take my place along with boys, many of whose fathers, uncles, cousins, and brothers had attended this school. For them the school was going to be familiar, for me most unfamiliar. Adding to my anxiety was the fact that I was also going to be one of 900 boys, only seven of whom were Black. I was a wreck and desperate to introduce myself wisely and well. In a conversation with my parents about proper introductions, one of my grandmothers happened upon the scene and offered some sage advice. She said, when it comes to introductions, when someone asks you who you are, tell \u27em you\u27re a child of God. That is the most important thing for each of you to remember about me, for it is the most important thing that you are to remember about yourself

Higgs with Hadronic Signatures

The decay of the Higgs boson to b quarks should be the dominant decay mode, but it has not yet been conclusively established. The LHC run 1 results are recalled and the current status of the LHC Run 2 studies is reviewed. The analysis is approaching decisive sensitivity.Comment: 4 page Moriond QCD 2017 writeu

Reliability analysis of single-phase photovoltaic inverters with reactive power support

Reactive power support is expected to be an emerging ancillary requirement for single-phase photovoltaic (PV) inverters. This work assesses related reliability issues and focuses on the second stage or inversion process in PV inverters. Three PV inverter topologies are analyzed and their reliability is determined on a component-by-component level. Limiting operating points are considered for each of these topologies. The capacitor in the dc link, the MOSFETs in the inverting bridge, and the output filter are the components affected. Studies show that varying power-factor operation with a constant real power output increases the energy storage requirement as well as the capacitance required in the dc link in order to produce the double-frequency power ripple. The overall current rating of the MOSFETs and output filter must also be sized to accommodate the current for the apparent power output. Modeling of the inverter verifies the conditions for each of the components under varying reactive power support commands. It is shown that the production of reactive power can significantly increase the capacitance requirement, but the limiting reliability issue comes from the increased output current rating of the MOSFETs

Finiteness and the falsification by fellow traveler property

We prove that groups enjoying the falsification by fellow traveler property are of type $F_3$, and have at most an exponential second order isoperimetric function.Comment: Appeared in 2002. I am putting all my past publications on arxi

Tilted accretion discs in cataclysmic variables: tidal instabilities and superhumps

We investigate the growth of tidal instabilities in accretion discs in a binary star potential, using three dimensional numerical simulations. As expected from analytic work, the disc is prone to an eccentric instability provided that it is large enough to extend to the 3:1 resonance. The eccentric disc leads to positive superhumps in the light curve. It has been proposed that negative superhumps might arise from a tilted disc, but we find no evidence that the companion gravitational tilt instability can grow fast enough in a fluid disc to create a measurable inclination. The origin of negative superhumps in the light curves of cataclysmic variables remains a puzzle.Comment: 7 pages, 7 figures, accepted for publication in MNRA

A qualitative study of adjustment to caring for an older spouse with psychiatric illness

An understanding of ways in which older carers' perceptions of their marital relationship and duty to their spouse underlie adjustment to care-giving is required for the development of acceptable and efficacious services for spouse carers. With this aim we conducted qualitative interviews with 20 spouses Of older people with a mental illness identified in a representative community study. While carers acknowledged distressing changes in their spouse, a history of reciprocity and intimacy emerged, comprising positive themes and perceived continuity which favourably influenced adjustment to care-giving. Those who still experience closeness in the relationship see themselves as coping and are reluctant to accept formal help. Others describe long-term unhappiness in marriage and experience feelings of entrapment in the role of carer. They require early and comprehensive services. Hypotheses regarding these themes are proposed

Carter-Payne homomorphisms and branching rules for endomorphism rings of Specht modules

Let n be a positive integer and let p be a prime. Suppose that we take a partition of n, and obtain another partition by moving a node from one row to a shorther row. Carter and Payne showed that if the p-residue of the removed and added positions is the same, then there is a non-zero homomorphism between the corresponding Specht modules for the symmetric group of degree n, defined over a field of characteristic p. In this paper we give a very simple description of such a homomorphism, as a map between polytabloids, using the action of a Murphy-Jucys element. We also present a proof that in this context the homomorphism space is 1-dimensional. S. Lyle has already proved the more general result for Iwahori-Hecke algebras. In the process we give a formula for the Carter-Payne homomorphism as a linear combination of semi-standard homomorphisms. Our methods allow us to compute a lower bound for where the image of this homomorphism lies in the Jantzen filtration of the codomain Specht module. As an application, we show that the endomorphism ring of the restriction of a Specht module to the symmetric group of degree n-1 is an explicit direct product of truncated polynomial rings. A. Kleshchev proved the analogous result for the restriction of irreducible modules.Comment: 19 pages, submitte

Granular synthesis for display of time-varying probability densities

We present a method for displaying time-varying probabilistic information to users using an asynchronous granular synthesis technique. We extend the basic synthesis technique to include distribution over waveform source, spatial position, pitch and time inside waveforms. To enhance the synthesis in interactive contexts, we "quicken" the display by integrating predictions of user behaviour into the sonification. This includes summing the derivatives of the distribution during exploration of static densities, and using Monte-Carlo sampling to predict future user states in nonlinear dynamic systems. These techniques can be used to improve user performance in continuous control systems and in the interactive exploration of high dimensional spaces. This technique provides feedback from users potential goals, and their progress toward achieving them; modulating the feedback with quickening can help shape the users actions toward achieving these goals. We have applied these techniques to a simple nonlinear control problem as well as to the sonification of on-line probabilistic gesture recognition. We are applying these displays to mobile, gestural interfaces, where visual display is often impractical. The granular synthesis approach is theoretically elegant and easily applied in contexts where dynamic probabilistic displays are required

Pointing Without a Pointer

We present a method for performing selection tasks based on continuous control of multiple, competing agents who try to determine the user's intentions from their control behaviour without requiring an explicit pointer. The entropy in the selection process decreases in a continuous fashion -- we provide experimental evidence of selection from 500 initial targets. The approach allows adaptation over time to best make use of the multimodal communication channel between the human and the system. This general approach is well suited to mobile and wearable applications, shared displays and security conscious settings