Solving the Uncalibrated Photometric Stereo Problem using Total Variation

International audienceIn this paper we propose a new method to solve the problem of uncalibrated photometric stereo, making very weak assumptions on the properties of the scene to be reconstructed. Our goal is to solve the generalized bas-relief ambiguity (GBR) by performing a total variation regularization of both the estimated normal field and albedo. Unlike most of the previous attempts to solve this ambiguity, our approach does not rely on any prior information about the shape or the albedo, apart from its piecewise smoothness. We test our method on real images and obtain results comparable to the state-of-the-art algorithms

PRACTICAL APPLICATION OF SUSPENSION CRITERIA SCENARIOS: RADIOTHERAPY.

In 2007, the European Commission (EC) commissioned a group of experts to undertake the revision of Report RP91 'Criteria for Acceptability of Radiological (including Radiotherapy) and Nuclear Medicine Installations' written in 1997. The revised draft report was submitted to the EC in 2010, which issued it for public consultation. The EC commissioned the same group of experts to consider the comments of the public consultation for further improvement of the revised report. The EC intends to publish the final report under its Radiation Report Series as RP162. This paper presents a selection of practical applications of suspension criteria scenarios in radiotherapy, mostly in brachytherapy, with special emphasis on the critical roles and responsibilities of qualified radiotherapy staff (radiation oncologists, medical physicists and radiotherapy technicians)

A Technique for Better Energy Management of Single-Stage Topology of Stand-Alone Photovoltaic System

This paper proposes a technique for energy managing of a stand-alone photovoltaic system. The proposed system employs a power processing inverter, which contains high PV voltage at the input to mitigate the magnitude of AC signal at the output, eliminating use of DC-DC converter and reduces the input capacitor size of PV array. To meet the power requirement of load and to maintain the maximum power point operation of PV array, battery bank is utilized with a bi-directional converter. An impedance model of the complete system is executed. Based on the model, the control architecture is designed which works in four modes: 1)  if load demands >  MPP of PV, additional current is extracted from the battery; 2) if load demands <  MPP of PV array, extra current is given to the battery; 3) only load management is utilized since the battery bank is not available because of over-charging or under-charging; 4) if irradiation varies then first mode is used for load requirement. The technique is designed which guarantees the maximum power point tracking of PV system even without using any intermediate stage of DC-DC converter, hence making it single-stage, MPPT is achieved by effectively controlling bi-directional converter used for battery charging and discharging purpose. To ensure better utilization of dc voltage enhanced efficiency and low less harmonic distortion, sinusoidal PWM technique is used to drive the inverter. Simulation results are carried out for ensuring better energy management along with MPPT operation demonstrated under uniform operating conditions

Automated uninterruptible power supply battery protector: case study of Tanzania atomic energy commission, Arusha-Tanzania

A Project Report Submitted in Partial Fulfilment of the Requirements for the Degree of Master of Science in Embedded and Mobile Systems of the Nelson Mandela African Institution of Science and TechnologyUninterruptible Power Supply (UPS) is electrical apparatus that provides emergency power to its load when the input power source fails and manages power fluctuations through its battery during power failure to allow a user to save work and shut down a system procedurally. The UPS’ electrical ability depends on its battery’s strength. At Tanzania Atomic Energy Commission (TAEC) users mostly leave their UPS on as they go home, and when there is blackout, the UPS batteries get drained to zero leading to a significant number of UPS getting damaged in a year. Automated Uninterruptible Power Supply Battery Protector (AUPSBP) is developed to protect UPS battery at the institution using Kanban Agile methodology which supported teamwork. The AUPSBP monitors the voltage from mains to UPS using a voltage sensor. When the sensor detects a lack of voltage from the mains to UPS, AUPSBP triggers timer counting down towards switching the UPS off. When tested, AUPSBP switched off the UPS when the set time of 5 minutes elapsed, and when UPS battery voltage was <100V protecting UPS battery from draining to zero during blackout. It sent Short Messages using Global System for Mobile communication when mains power was switched off, and when UPS was switched off before the set time of 5 minutes elapsed. The AUPSBP is effective for switching off UPS before its battery drains to zero to prevent battery damage on different types and sizes of UPSs with only changes in switch and timer. Therefore, AUPSBP is needed to protect UPS at TAEC

Composite variable formulations for express shipment service network design

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (p. 181-187).In this thesis, we consider large-scale network design problems, specifically the problem of designing the air network of an express shipment (i.e., overnight) delivery operation. We focus on simultaneously determining the route structure, the assignment of fleet types to routes, and the flow of packages on aircraft. Traditional formulations for network design involve modeling both flow decisions and design decisions explicitly. The bounds provided by their linear programming relaxations are often weak. Common solution strategies strengthen the bounds by adding cuts, but the shear size of the express shipment problem results in models that are intractable. To overcome this shortcoming, we introduce a new modeling approach that 1) removes the flow variables as explicit decisions and embeds them within the design variables and 2) combines the design variables into composite variables, which represent the selection of multiple aircraft routes that cover the demands for some subset of commodities. The resulting composite variable formulation provides tighter bounds and enables very good solutions to be found quickly. We apply this type of formulation to the express shipment operations of the United Parcel Service (UPS). Compared with existing plans, the model produces a solution that reduces the number of required aircraft by almost 11 percent and total annual cost by almost 25 percent. This translates to potential annual savings in the hundreds of millions of dollars. We establish the composite variable formulation to be at least as strong as the traditional network design formulation, even when the latter is strengthened by Chvital-Gomory rounding, and we demonstrate cases when strength is strictly improved. We also place the composite variable formulation in a more general setting by presenting it as a Dantzig-Wolfe decomposition of the traditional (intractable) network design formulation and by comparing composite variables to Chvital-Gomory cuts in the dual of a related formulation. Finally, we present a composite variable formulation for the Pure Fixed Charge Transportation Problem to highlight the potential application of this approach to general network design and fixed-charge problems.by Andrew P. Armacost.Ph.D

Schematics of Graphs and Hypergraphs

Graphenzeichnen als ein Teilgebiet der Informatik befasst sich mit dem Ziel Graphen oder deren Verallgemeinerung Hypergraphen geometrisch zu realisieren. Beschränkt man sich dabei auf visuelles Hervorheben von wesentlichen Informationen in Zeichenmodellen, spricht man von Schemata. Hauptinstrumente sind Konstruktionsalgorithmen und Charakterisierungen von Graphenklassen, die für die Konstruktion geeignet sind. In dieser Arbeit werden Schemata für Graphen und Hypergraphen formalisiert und mit den genannten Instrumenten untersucht. In der Dissertation wird zunächst das „partial edge drawing“ (kurz: PED) Modell für Graphen (bezüglich gradliniger Zeichnung) untersucht. Dabei wird um Kreuzungen im Zentrum der Kante visuell zu eliminieren jede Kante durch ein kreuzungsfreies Teilstück (= Stummel) am Start- und am Zielknoten ersetzt. Als Standard hat sich eine PED-Variante etabliert, in der das Längenverhältnis zwischen Stummel und Kante genau 1⁄4 ist (kurz: 1⁄4-SHPED). Für 1⁄4-SHPEDs werden Konstruktionsalgorithmen, Klassifizierung, Implementierung und Evaluation präsentiert. Außerdem werden PED-Varianten mit festen Knotenpositionen und auf Basis orthogonaler Zeichnungen erforscht. Danach wird das BUS Modell für Hypergraphen untersucht, in welchem Hyperkanten durch fette horizontale oder vertikale – als BUS bezeichnete – Segmente repräsentiert werden. Dazu wird eine vollständige Charakterisierung von planaren Inzidenzgraphen von Hypergraphen angegeben, die eine planare Zeichnung im BUS Modell besitzen, und diverse planare BUS-Varianten mit festen Knotenpositionen werden diskutiert. Zum Schluss wird erstmals eine Punktmenge von subquadratischer Größe angegeben, die eine planare Einbettung (Knoten werden auf Punkte abgebildet) von 2-außenplanaren Graphen ermöglicht

The UPS Problem

The UPS Problem consists of the following: given a vertex set V , vertex probabilities (p v ) v2V , and distances l : V 2 ! R + that satisfy the triangle inequality, nd a Hamilton cycle such that the expected length of the shortcut that skips each vertex v with probability 1 p v (independently of the others) is minimum. This problem appears in the following context. Drivers of delivery companies visit customers daily to deliver packages. For the company, the shorter the distance traversed, the better. For a driver, routes that change dramatically from one day to the other are inconvenient; it is better if one only has to shortcut a xed route. The UPS problem, whose objective captures these two points of view, is at least as hard to approximate as the Metric TSP. We show that the performance ratio of a TSP tour for the UPS problem is 1=p min , where p min := min v2V p v . We also show that this is tight. Consequently, Christodes&apos; algorithm for the TSP has a performance ratio of ..