3,183 research outputs found
Total and partial cloud amount detection during summer 2005 at Westerland (Sylt, Germany)
The detection of cloudiness is investigated by means of partial and total cloud amount estimations from pyrgeometer radiation measurements and visible all-sky imager observations. The measurements have been performed in Westerland, a seaside resort on the North Sea island of Sylt, Germany, during summer 2005.
An improvement to previous studies on this subject resulting in the first time partial cloud amounts (PCAs), defined as cloud amounts without high clouds calculated from longwave downward radiation (LDR) according to the APCADA algorithm (DĂĽrr and Philipona, 2004), are validated against both human observations from the National Meteorological Servive DWD at the nearby airport of Sylt and digital all-sky imaging. The aim is to establish the APCADA scheme at a coastal midlatitude site for longterm observations of cloud cover and to quantify errors resulting from the different methods of detecting cloudiness.
Differences between the resulting total cloud amounts (TCAs), defined as cloud amount for all-cloud situations, derived from the camera images and from human observations are within ±1 octa in 72% and within ±2 octa in 85% of the cases. Compared to human observations, PCA measurements, according to APCADA, underestimate the observed cloud cover in 47% of all cases and the differences are within ±1 octa in 60% and ±2 octa in 74% of all cases. Since high cirrus clouds can not be derived from LDR, separate comparisons for all cases without high clouds have been performed showing an agreement within ±1(2) octa in 73(90)% for PCA and also for camera-derived TCA. For this coastal mid-latitude site under investigation, we find similar though slightly smaller agreements to human observations as reported by Dürr and Philipona (2004). Though limited to daytime, the cloud cover retrievals from the sky imager are not really affected by cirrus clouds and provide a more reliable cloud climatology for all-cloud conditions than APCADA
Tensile loaded membrane constructions without cutting patterns - computer based modeling and analysis of high points
In this paper, the high points of a stretch-tent construction are analyzed by using two different software programs. The modeling and results are verified by a puncture resistance testing. The possibilities and limits of the software programs are shown as well as the further research opportunities
Equity-Linked Pension Schemes with Guarantees
This paper analyses the relationship between the level of a return guarantee in an equity-linked pension scheme and the proportion of an investor's contribution needed to finance this guarantee. Three types of schemes are considered: investment guarantee, contribution guarantee and participation surplus. The evaluation of each scheme involves pricing an Asian option, for which relatively tight upper and lower bounds can be calculated in a numerically efficient manner. We find a negative (and for two contracts pecifications also concave) relationship between the participation in the surplus return of the investment strategy and the guarantee level in terms of a minimum rate of return. Furthermore, the introduction of a possibility of early termination of the contract (e.g. due to the death of the investor) has no qualitative and very little quantitative impact on this relationship.pension funds; forward risk adjusted measure; Asian option
Subject and Predicate: A Contribution to the Theory of Grammatical Analysis
Abstract Not Provided
Design and Implementation of a Precision Three-Dimensional Binocular Image Tracker for Departing Aircraft
Abstract
This dissertation presents the result of the conceptualization, design and implementation of a new, novel and low cost Binocular Tracking System for departing Aircraft. This system is a unique design due to the commercial off-the-shelf (COTS) components used and the distinct modular algorithms developed for the implementation of tracking aircraft.
Recent economic pressures and changing Federal Aviation Administration (FAA) regulations have raised serious concern that obstacle clearance requirements are not being met on commercial aircraft departure. Moreover, local airport procedures do not always align with the requirements for Terminal Instrument Procedures (TERPs) established by the FAA. The flight track data collected by this system is being used by the FAA to assess the magnitude of the problem and determine steps to align airport and TERPs procedures, while also mitigating obstacle clearance violations and thus the risk of departing aircraft encountering an obstacle.
Each of the binocular tracking systems uses three cameras. One camera is directed towards the runway, initializes the tracking algorithms, and identifies the type of aircraft. The other two cameras form the binocular tracking system. These dual cameras are aligned in a vergent stereo configuration across the departure path to provide the maximum overlap in the field of view to produce a superior depth resolution.
The modular tracking algorithms allow a large volume of tracking data to be accumulated that provides the FAA information on departing aircraft. This dissertation discusses the details of the binocular tracking system’s conceptualization, design, and implementation, including hardware and software development of the tracking system. This dissertation also includes system setup, data collection, processing and error analysis of the system’s performance in the field
The Basic Course in Communication Theory: A Shift in Emphasis
This essay calls for a change in how the introductory communication theory course is taught. Standard models and texts are examined, described and critiqued. The standard model of communication theory depicts theory as a body of knowledge to be studied and applied to specific situations. This one dominant paradigm of communication theory constrains other possible approaches to understanding and teaching communication theory. The remainder of the essay offers a rationale for a shift in the teaching of communication theory, and directions for preliminary changes in the teaching of communication theory
Logic and Emotion, Persuasion and Argumentation: \u27Good Reasons\u27 as an Educational Synthesis
The purpose of this essay is three-fold. First, I will summarize the history and development of persuasion and rhetoric in the classical and renaissance world, demonstrating the manner in which argumentation, or conviction by means of logical proof, and persuasion, or conviction by means of a unified appeal to emotions and reasons became separated. Second, I will look at the manner in which persuasion and argumentation are presented educationally today by analyzing four of the most popular public speaking texts. Finally, I will argue that there is a more effective method for teaching the combined principles of argumentation and persuasion, as can be seen in the works of Karl Wallace, Walter Fisher and Douglas Hesse, and as seen in the argumentation texts of Barbara Warnick and Edward Inch and also Josina Makau
Critical Thinking Is/As Communication
This essay argues for the place of critical thinking in the basic communication course. Included in the argument is a discussion and critique of traditional modes of critical thinking, an analysis of an alternative approach to critical thinking, the grounding of this alternative approach in a classical communication model, a discussion of why the basic course in communication is the most appropriate home for the teaching of critical thinking, and a sample approach to teaching critical thinking in the basic course
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