Absolute beam position monitoring using HOM-damper signals

To preserve the required beam quality in an e+/e- collider it is necessary to have a very precise beam position control at each accelerating cavity. An elegant method to avoid additional length and beam disturbance is the usage of signals from existing HOM-dampers. The magnitude of the displacement is derived from the amplitude of a dipole mode whereas the sign follows from the phase comparison of a dipole and a monopole HOM. To check the performance of the system, a measurement setup has been built with an antenna which can be moved with micrometer resolution to simulate the beam. Furthermore we have developed a signal processing to determine the absolute beam displacement. Measurements on the HOM-damper cell can be done in the frequency domain using a network analyser. Final measurements with the nonlinear time dependent signal processing circuit has to be done with very short electric pulses simulating electron bunches. Thus, we have designed a sub nanosecond pulse generator using a clipping line and the step recovery effect of a diode. The measurement can be done with a resolution of about 10 micrometers. Measurements and numerical calculations concerning the monitor design and the pulse generator are presented

Dynamic demand management and online tour planning for same-day delivery

For providers to stay competitive in a context of continued growth in e-retail sales and increasing customer expectations, same-day delivery options have become very important. Typically, with same-day delivery, customers purchase online and expect to receive their ordered goods within a narrow delivery time span. Providers thus experience substantial operational challenges to run profitable tours and generate sufficiently high contribution margins to cover overhead costs. We address these challenges by combining a demand-management approach with an online tour-planning approach for same-day delivery. More precisely, in order to reserve capacity for high-value customer orders and to guide customer choices toward efficient delivery operations, we propose a demand-management approach that explicitly optimizes the combination of delivery spans and prices which are presented to each incoming customer request. The approach includes an anticipatory sample-scenario based value approximation, which incorporates a direct online tour-planning heuristic. It does not require extensive offline learning and is scalable to realistically sized instances with multiple vehicles. In a comprehensive computational study, we show that our anticipatory approach can improve the contribution margin by up to 50% compared to a myopic benchmark approach. We also show that solving an explicit pricing optimization problem is a beneficial component of our approach. More precisely, it outperforms both a pure availability control and a simple pricing rule based on opportunity costs. The latter idea is one used in other approaches for related dynamic pricing problems dealt with in the literature

The influence of wakefields on superconducting TESLA-cavities in FEL-operation

Due to the additional need of very short bunches for the FEL operation with the TESLA-machine strong wakefield effects are expected. One third of the total wakefield energy per bunch is radiated into the frequency region above the energy gap of Cooper pairs in superconducting niobium. The energy of the cooper pairs in superconducting niobium at 2 K corresponds to a frequency of 700 GHz. An analytical and experimental estimation for the overall energy loss of the FEL bunch above energy gap is presented. The analytical method is based on a study from R. B. Palmer [1]. The results of the wakefield estimations are used to calculate possible quality factor reduction of the TESLA cavities during FEL operation. Results are presented

Energy Propagation through the TESLA Channel: Measurements with Two Waveguides Modes

A new method for the determination of S-matrices of devices in multimoded waveguides and first experimental experiences are presented. The theoretical foundations are given. The scattering matrix of a TESLA copper cavity at a frequency above the cut-off of the second waveguide mode has been measured

Fabrication, analysis and manipulation of systems with spin-polarized electronic states

Diese Arbeit thematisiert die Herstellung und Manipulation von Systemen mit spin-aufgespaltenen Oberflächenzuständen. In einer hochauflösenden SPA-LEED-Studie wird das Wachstum von Bi2Se3 untersucht. Es wird gezeigt, dass dünne Bi2Se3-Filme innerhalb der ersten sechs Quintupel-Lagen (QL) verspannt mit einer vergrößerten Gitterkonstante aufwachsen. Dabei wächst bereits die erste QL epitaktisch. Durch die van-der-Waals-Bindung zwischen den einzelnen QL können diese aufeinander gleiten. Die Filme mit der geringsten Verspannung werden auf einem Bi-rekonstruierten Si(111)-Substrat bei T = 250° C erzeugt und haben für unverspannte Schichten eine laterale Gitterkonstante von a = 0,4136 nm. Durch ex-situ XRD-Messungen wird die vertikale Gitterkonstante zu c = 2,8559 nm bestimmt. Über die Temperaturabhängigkeit der Beugungsintensität kann für Bi2Se3 eine Oberflächen-Debye-Temperatur von T = 89 K ermittelt werden. Nachdem das Wachstum von Bi(111) auf Si(001)-Substraten etabliert ist, wird das Wachstum auf Si(111) optimiert und charakterisiert. Die so gewachsenen Bi(111)-Filme haben Terrassengrößen, die nur durch die Fehlneigung der Probe bestimmt sind. Der Großteil der Ladungsträger befindet sich in Bi-Filmen im Oberflächenzustand. Durch die gezielte Deposition einzelner Bi-Adatome wird der Streuquerschnitt eines einzelnen Bi-Atoms bestimmt. Es zeigt sich in LT-STM-Messungen, dass der Streuquerschnitt einzelner Bi-Adatome und kleiner Inseln identisch ist. Die Ladungsträger werden an strukturellen Defekten, wie einer Stufenkante, gestreut und bilden stehende Wellen. Die gemessenen charakteristischen Periodizitäten liegen auf der Bi(111)-Terrasse für E = 1 meV bei etwa l = 4 nm. Vor- und Rückwärtsstreuung können identifiziert werden. Bei der Verwendung anderer Adsorbat-Systeme wird erstmals ein barrierefreier Einbau von 3d-Übergangsmetallen in die Bi(111)-Oberfläche beobachtet. Durch LT-STM Messungen wird für Co, Fe, Ni und Cu bestätigt, dass diese barrierefrei bei T = 5 K in den Film eindringen und gebunden werden. Ein, nur nahe der Fermienergie sichtbares, dreizähliges Streupattern von mehr als 10 nm Durchmesser wird als Indiz für ein eingebautes Subsorbat-Atom verwendet. Über eine STM-Messung im constant-height-Tunnelmodus kann eine lokale Variation der Zustandsdichte um einen Faktor 3 beobachtet werden. Weiterhin wird der Einbau von Ag und Au in die Bi(111)-Oberfläche verifiziert. Die eingebauten Subsorbat-Atome bleiben bis zu einer Temperatur von T = 255 K in ihrem Einbauplatz stabil. Die maximal mögliche Menge an Subsorbat-Atomen beträgt etwa 1 nm^-2. DFT-Rechnungen bestätigen den barrierefreien Einbau und können den Effekt auf eine Hybridisierung der 4s-Orbitale und eine anschließende Polarisation der 3d-Orbitale zurückführen. Der Einbauplatz wird dabei eindeutig innerhalb der ersten BL bestätigt und ist siebenfach koordiniert. Durch die starke Modulation der lokalen Zustandsdichte, ist von einem großen Einfluss einzelner Ad- und Subsorbat-Atome auf die Leitfähigkeit eines Bi-Films auszugehen. Dies wird in Magnetotransport-Messungen bestätigt. Dabei kann der enorme Effekt geringster Bedeckungen an Bi-Adatomen und Fe-, und Co-Subsorbat-Atomen im Bereich unterhalb eines Prozentes einer ML gezeigt werden. Obgleich der initiale Anstieg bei allen Systemen vergleichbar ist, kommt es durch die Subsorption zu einer Ladungsträgerinjektion und pro eingebautem Subsorbat-Atom werden 0,5 Löcher in den Film injeziert

A review of choice-based revenue management : theory and methods

Over the last fifteen years, the theory and practice of revenue management has experienced significant developments due to the need to incorporate customer choice behavior. In this paper, we portray these developments by reviewing the key literature on choice-based revenue management, specifically focusing on methodological publications of availability control over the years 2004–2017. For this purpose, we first state the choice-based network revenue management problem by formulating the underlying dynamic program, and structure the review according to its components and the resulting inherent challenges. In particular, we first focus on the demand modeling by giving an overview of popular choice models, discussing their properties, and describing estimation procedures relevant to choice-based revenue management. Second, we elaborate on assortment optimization, which is a fundamental component of the problem. Third, we describe recent developments on tackling the entire control problem. We also discuss the relation to dynamic pricing. Finally, we give directions for future research

Mode propagation in an iris type accelerator section loaded with single heavily HOM-damped cells

The wakefield effects in accelerator sections for future linear colliders will be reduced either by damping by detuning or by a combination of both. For the DESY/THD linac [1] it is forseen to employ heavily HOM-damped cells to provide a strong coupling to the TE/TM11-dipole passband as well as to the TM/TE11-dipole passband. For our experiments we have used wall-slotted damping cells. This leads to several problems concerning the propagation of fundamental and HOM-modes. Experimental investigations have been done. Results are presented

Quality factor measurements in cavities with mode overlap

A new method of measuring quality factors in cavities is presented. This method is well suited to measure quality factors in undamped cavities as well as in heavily damped cavities, and in addition this method provides a possibility of separating modes and measuring quality factors especially in cases of overlapping modes. Measurements have been carried out on HOM-damped cavities for the DESY/THD linear collider project. Results are presented

A review of revenue management : recent generalizations and advances in industry applications

Originating from passenger air transport, revenue management has evolved into a general and indispensable methodological framework over the last decades, comprising techniques to manage demand actively and to further improve companies’ profits in many different industries. This article is the second and final part of a paper series surveying the scientific developments and achievements in revenue management over the past 15 years. The first part focused on the general methodological advances regarding choice-based theory and methods of availability control over time. In this second part, we discuss some of the most important generalizations of the standard revenue management setting: product innovations (opaque products and flexible products), upgrading, overbooking, personalization, and risk-aversion. Furthermore, to demonstrate the broad use of revenue management, we survey important industry applications beyond passenger air transportation that have received scientific attention over the years, covering air cargo, hotel, car rental, attended home delivery, and manufacturing. We work out the specific revenue management-related challenges of each industry and portray the key contributions from the literature. We conclude the paper with some directions for future research

Peptide Signatures for Prognostic Markers of Pancreatic Cancer by MALDI Mass Spectrometry Imaging

Simple Summary: Pancreatic cancer remains one of the most lethal tumor entities worldwide given its overall 5-year survival after diagnosis of 9%. Thus, further understanding of molecular changes to improve individual prognostic assessment as well as diagnostic and therapeutic advancement is crucial. The aim of this study was to investigate the feasibility of Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) to identify specific peptide signatures linked to established prognostic parameters of pancreatic cancer. In a patient cohort of 18 patients with exocrine pancreatic cancer after tumor resection, MALDI imaging analysis additional to histopathological assessment was performed. Applying this method to tissue sections of the tumors, we were able to identify discriminative peptide signatures corresponding to nine proteins for the prognostic histopathological features lymphatic vessel invasion, lymph node metastasis and angioinvasion. This demonstrates the technical feasibility of MALDI-MSI to identify peptide signatures with prognostic value through the workflows used in this study. Abstract: Despite the overall poor prognosis of pancreatic cancer there is heterogeneity in clinical courses of tumors not assessed by conventional risk stratification. This yields the need of additional markers for proper assessment of prognosis and multimodal clinical management. We provide a proof of concept study evaluating the feasibility of Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) to identify specific peptide signatures linked to prognostic parameters of pancreatic cancer. On 18 patients with exocrine pancreatic cancer after tumor resection, MALDI imaging analysis was performed additional to histopathological assessment. Principal component analysis (PCA) was used to explore discrimination of peptide signatures of prognostic histopathological features and receiver operator characteristic (ROC) to identify which specific m/z values are the most discriminative between the prognostic subgroups of patients. Out of 557 aligned m/z values discriminate peptide signatures for the prognostic histopathological features lymphatic vessel invasion (pL, 16 m/z values, eight proteins), nodal metastasis (pN, two m/z values, one protein) and angioinvasion (pV, 4 m/z values, two proteins) were identified. These results yield proof of concept that MALDI-MSI of pancreatic cancer tissue is feasible to identify peptide signatures of prognostic relevance and can augment risk assessment