低温地层钻进特点及其钻井液技术现状综述

在低温地层(主要包括冰层、极地、永冻层以及赋存天然气水合物的永冻层)的钻进对于科学研究和矿产与油气资源的勘探开发都非常重要。介绍了低温地层钻进的国内外研究背景,分析了其钻进特点,对相关的低温钻井液的研究现状和应用情况进行了讨论,对低温地层钻进及其钻井液的研究提出了几点建议。     

More Than Stories With Buttons: Narrative,Mechanics, and Context as Determinants of Player Experience in Digital Games

Recent research has attempted to describe meaningful experiences with entertainment media that go beyond hedonic enjoyment. Most of this research focuses on noninteractive media, such as film and television. When applied to digital games, however, such research needs to account for not only the content of the medium, but also the unique dimensions of digital games that distinguish them from noninteractive media. Experiences with digital games are shaped by the game mechanics that define the users' interaction with game content, as well as by the opportunities for social interaction that many games offer. We argue that the complex interplay of these dimensions (narrative, mechanics, and context) facilitates or inhibits meaningful user experiences in ways that are unique to digital games.     

Implementation of electron beam grey scale lithography and proximity effect correction for silicon nanowire device fabrication

An electron beam lithography exposure strategy combining efficient proximity effect correction (PEC) with multi-pass grey scale is compared with a more conventional strategy based on a single-pass exposure without PEC. Exposure results for different types of nanowire structures are presented. Line edge and line width roughness (LER and LWR) values for both approaches are determined. The novel exposure strategy presented in this work reduced LER by ∼25% and LWR by ∼40%.     

Kraftwerkseigenschaften von Windenergieanlagen hinsichtlich Kurzschlussverhalten, Engpass- und Blindleistungsmanagement sowie Spannungsregelung

The increasing number of wind turbines will lead to new demands for transmission and distribution system control in the years to come. In order to ensure a smooth integration of wind energy into an electrical energy system structure, wind farms will have to possess power plant properties and be able to provide ancillary services. The ENERCON concept offers solutions not only for critical situations, such as short-circuits and bottlenecks in the grid, but also for normal operation, such as reactive power management or voltage control. Wind farms will essentially function in a manner similar to conventional power plants and moreover offer additional advantages in the distribution grid.     

Internet traffic engineering

The main goal of Internet traffic engineering is to efficiently optimize the performance of operational networks in order to avoid the well-known shortcomings of the typical destination-based IP routing. Traffic engineering attempts to reduce or even avoid congestion hot spots and to improve resource utilization across the backbone IP network. During the last years traffic engineering has become an inevitable tool concerning performance optimization in large Internet backbones. The core objective of this paper is to give an overview of the architectures and mechanisms for traffic engineering.     

Nichtlinearer digitaler Reibungsbeobachter zur adaptiven Reibungskompensation bei Bewegungsregelungen

Friction can deteriorate the tracking behavior of motion control. By use of a friction observer an estimated value of the friction can be determined and through adaptive compensation of the friction its influence can be weakened. The following article developes a new digital nonlinear friction observer on ground of an already known continuous nonlinear friction observer, which can easily be parametrized. A mechanical model is used to compare this nonlinear friction observer with a linear one during simulations and real time investigation. The investigation shows that the effect of deterioration of the tracking behavior through friction is less significant with the new digital nonlinear friction observer than with the linear friction observer.     

Macrodiversity analysis of anM-ary noncoherent orthogonal DS/CDMA system on shadowed Rayleigh channels

DS/CDMA noncoherentM-ary orthogonal signaling is presented in a hexagonal cell with three and six corner-based antennas. Multipath Rayleigh channel with lognormal shadowing and perfect power control are assumed. The asynchronous case (uplink) is studied. Bit error rate analysis is carried out to investigate the benefits of combining theM-ary orthogonal signaling and macrodiversity techniques either with uncorrelated or correlated base stations. Comparative analysis between the one central antenna arrangement and the proposed one is presented. The results show that the combination ofM-ary signaling with multiple corner-based antennas improves system performance especially in terms of accommodating more users and supporting new services. The results also show that shadowing does not degrade system performance significantly.     

Shape optimization of inclined ribs as heat transfer augmentation device

This work presents numerical optimization techniques for the design of a rectangular channel with inclined ribs toenhance turbulent heat transfer.The response surface method with Reynolds-averaged Navier-Stokes analysis isused for optimization.Shear stress transport turbulence model is used as a turbulence closure.Computational re-sults for local heat transfer rate show a reasonable agreement with the experimental data.Width-to-rib height ratioand attack angle of the rib are chosen as design variables.The objective function is defined as a linear combina-tion of heat-transfer and friction-loss related terms with the weighting factor.Full-factorial experimental designmethod is used to determine the data points.Optimum shapes of the channel have been obtained in a range of theweighting factor.     

FGTO — A fine structured GTO-thyristor with improved switching characteristics

Contents A fine structured GTO thyristor, abbreviated FGTO, has been developed to improve the switching characteristics. The new device has a cathode finger width of only 20 m and can be turned off without a negative gate bias at an anode current level of more than 200 A/cm². The turn-off time can be shortened down tot _off 500 ns by increasing the negative gate current. A snubber circuit is not necessary to turn off the FGTO's. The maximum rate of rise of anode voltage du/dl reaches more than 10 kV/s. Analytical models are developed to describe the turn-off transients of the FGTO's. Good agreement between the theoretical and experimental results could be achieved.

---

FGTO — Ein feinstrukturierter GTO-Thyristor mit verbessertem Schaltverhalten

Übersicht Zur Verbesserung des Schaltverhaltens ist ein feinstrukturierter GTO-Thyristor, abgekürzt FGTO, entwickelt worden. Dieses neue Bauelement hat eine Kathoden-streifenbreite von nur 20 m und kann ohne negative Gatevorspannung bei einer Anodenstromdichte von mehr als 200 A/cm² abgeschaltet werden. Die Abschaltzeit läßt sich durch Erhöhung des negativen Gatestroms bis zut _off 500 ns verkürzen. Beim Abschalten von FGTOs ist keine RC-Beschaltung erforderlich. Der maximale du/dl-Wert erreicht mehr als 10 kV/s. Zur Beschreibung des Abschalt-verhaltens von FGTOs werden analytische Modelle entwickelt, die eine gute Übereinstimmung mit den Meßergebnissen liefern.

     

Algorithmen zur Pulsweitenmodulation für Wechselrichter mit in Echtzeit berechnetem Pulsmuster

Übersicht Mit Hinblick auf die zunehmend Verbreitung findende Pulsmusterberechnung in Echtzeit werden in dem Aufsatz Gesichtspunkte diskutiert, die sich aus den Eigenschaften des leistungselektronischen Stellgliedes, des Pulswechselrichters, ergeben. Die bei Abtastregelungen für die Dauer einer Abtastperiode konstante Stellgröße muß bei ihm durch Pulsweitenmodulation in ein Pulsmuster mit konstanter Amplitude und Pulsen variabler Breite umgesetzt werden. Durch ein neues Verfahren mit versetzter Abtastung haben dabei Rechentotzeiten bis zur Dauer einer halben Abtastperiode keinen Einfluß mehr auf das Pulsmuster.

---

Algorithms for pulswidth modulation of inverters with online calculated pulse patterns

Contents Online calculation of pulse patterns will be employed more intensively in the future. Aspects concerning the powereleotronic circuit, the pulsewidth-modulated inverter, are to be discussed. The set value being constant for the duration of a sampling interval, has to be converted by a modulation algorithm into a pulse pattern with constant amplitude and pulses of variable width. Calculation dead-times up to half of sampling interval have no influence on the pulse pattern when using a new algorthm with shifted sampling instants.

---

---

Herrn Prof. Dr.-Ing. Klemens Heumann zum 60. Geburtstag gewidmet