Aeroelastic analysis for propellers - mathematical formulations and program user's manual

Mathematical development is presented for a specialized propeller dedicated version of the G400 rotor aeroelastic analysis. The G400PROP analysis simulates aeroelastic characteristics particular to propellers such as structural sweep, aerodynamic sweep and high subsonic unsteady airloads (both stalled and unstalled). Formulations are presented for these expanded propeller related methodologies. Results of limited application of the analysis to realistic blade configurations and operating conditions which include stable and unstable stall flutter test conditions are given. Sections included for enhanced program user efficiency and expanded utilization include descriptions of: (1) the structuring of the G400PROP FORTRAN coding; (2) the required input data; and (3) the output results. General information to facilitate operation and improve efficiency is also provided

Open Vehicular Data Interfaces for In-Car Context Inference

In this paper, we present a concept for an open vehicular data interface and describe it's components and architecture. We discuss the enabled applications in the context of advanced driver assistance systems with a focus on humanmachine interfaces, vehicle-to-x (V2X) communication and context inference systems. We conclude by a presentation of the initial implementation and deployed system

An Efficient Two-Party Protocol for Approximate Matching in Private Record Linkage

The task of linking multiple databases with the aim to identify records that refer to the same entity is occurring increasingly in many application areas. If unique identifiers for the entities are not available in all the databases to be linked, techniques that calculate approximate similarities between records must be used for the identification of matching pairs of records. Often, the records to be linked contain personal information such as names and addresses. In many applications, the exchange of attribute values that contain such personal details between organisations is not allowed due to privacy concerns. The linking of records between databases without revealing the actual attribute values in these records is the research problem known as 'privacy-preserving record linkage' (PPRL).While various approaches have been proposed to deal with privacy within the record linkage process, a viable solution that is well applicable to real-world conditions needs to address the major aspect of scalability of linking very large databases while preserving security and linkage quality. We propose a novel two-party protocol for PPRL that addresses scalability, security and quality/ accuracy. The protocol is based on (1) the use of reference values that are available to both database owners, and allows them to individually calculate the similarities between their attribute values and the reference values; and (2) the binning of these calculated similarity values to allow their secure exchange between the two database owners. Experiments on a real-world database with nearly two million records yield linkage results that have a linear scalability to large databases and high linkage accuracy, allowing for approximate matching in the privacy-preserving context. Since the protocol has a low computational burden and allows quality approximate matching while still preserving the privacy of the databases that are matched, the protocol can be useful for many real-world applications requiring PPRL

Cybersecurity Index for undergraduate computer science courses in the UK

The paper proposes a novel index to classify how well UK Computer Science courses articulate cybersecurity-related content through their course/module pages. The aim of this work is to raise awareness among British Universities to pay more attention to include and standardize cybersecurity content in computer science courses. Our results show that 80% of analyzed courses scored 1 or 2-stars on a 5-Stars scale. The results also suggest the need for a formal delivery of cybersecurity content from the first year of the courses and possibly in a collaborative manner with the British Computer Society (BCS). To emphasize cybersecurity education in mitigating security lapses, the analogy is: it is better if most people know how to use a match than to train many fire-fighters

Temporal Price Dispersion: Evidence from an Online Consumer Electronics Market

Economic theory indicates that E-retailers competing at price comparison sites, such as Shopper.com, must charge prices that cannot be systematically predicted by their rivals. Consistent with theory, we find significant variation in the identity of the lowprice firm as well as the level of the lowest price for 36 of the best-selling consumer electronics products sold at Shopper.com between November 1999 and May 2001. The observed pricing patterns can be explained by firms engaging in short-term price promotions in an attempt to avoid the deleterious outcome associated with price competition. Based on our arguments and the evidence presented, the managerial implications are clear: Strategic unpredictability in prices—through the use of hit and run sales—is a widely used and effective weapon for avoiding all-out price competition in online markets.Temporal price dispersion, price comparison sites, e-retail, sales promotion

Comparative analysis of lost circulation material particle size and degradation in drilling fluids

textLost Circulation Materials (LCM) are used to plug natural and induced fractures to minimize drilling fluid loss to formations. Various LCMs are available in field application, such as calcium carbonate and graphite. Design of the particle size distribution is crucial to successfully mitigate loss circulation. It is common industry practice to rely on the particle size distribution as specified by the product data sheet when designing lost circulation pills. During mud circulation, there are several instances where LCMs are exposed to high shear rates, such as during fluid mixing at the hopper, going through mud pumps, and exiting through the bit nozzles. Using sensitive focused beam reflectance measurement (FBRM) techniques, reliable laser diffraction and sophisticated image analysis, we have found that size degradation of calcium carbonate and graphite under such shearing conditions occurs at a lower shearing rate - and to a much larger extent - than previously assumed. This, then, calls into question the effectiveness of calcium carbonate and graphite for LCM applications that rely on size maintenance for effective bridging purposes.. Based on the experimental results, the field personnel can take size degradation effects into account and compensates accordingly. Unexpectedly, particle measurements from sieve analysis, FBRM, laser diffraction and image analysis are quantitatively different. This can be attributed to the various definitions of particle diameters and the limitation of each techniques. Image analysis provides the most accurate particle sizing information but the reproducibility of the corresponding equipment is questionable. Laser diffraction is fast and reliable but will be affected by the sampling method and the degree of dispersion. FBRM requires no dilution to the sample, but provides chord length measurement which is very different from the equivalent spherical diameter (the prevailing diameter definition). In this study, we will show the size degradation results of calcium carbonate and graphite, and the detailed evaluation of the three commercial particle size analyzers used in the experiments.Petroleum and Geosystems Engineerin

Comprehensive rotorcraft analysis methods

The development and application of comprehensive rotorcraft analysis methods in the field of rotorcraft technology are described. These large scale analyses and the resulting computer programs are intended to treat the complex aeromechanical phenomena that describe the behavior of rotorcraft. They may be used to predict rotor aerodynamics, acoustic, performance, stability and control, handling qualities, loads and vibrations, structures, dynamics, and aeroelastic stability characteristics for a variety of applications including research, preliminary and detail design, and evaluation and treatment of field problems. The principal comprehensive methods developed or under development in recent years and generally available to the rotorcraft community because of US Army Aviation Research and Technology Activity (ARTA) sponsorship of all or part of the software systems are the Rotorcraft Flight Simulation (C81), Dynamic System Coupler (DYSCO), Coupled Rotor/Airframe Vibration Analysis Program (SIMVIB), Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics (CAMRAD), General Rotorcraft Aeromechanical Stability Program (GRASP), and Second Generation Comprehensive Helicopter Analysis System (2GCHAS)