Kinetics of Domain Growth in Ordered Ni4Mo

The kinetics of domain growth in Ni4Mo in the temperature range of 600 to 850 °C were investigated using transmission electron microscopy. It was found that domain growth in Ni₄Mo is analogous to metallurgical grain growth and can be described by the expressionD ⁿ =kt, whereD is the average domain size, t is the aging time, k is a constant, and the exponent n is the reciprocal of the slope of the log D vs log t plot. The value of n changed with temperature from 2.0 at 850 and 800 °C to 2.9 at 700 and 600 °C. This change was explained in terms of relative domain orientation effects. The activation energy for domain growth was obtained as 69 Kcal/mole (2.9 × 105 Joules/mole) in the temperature range of 800 to 850 °C and as 92 Kcal/mole (3.85 x 105 Joules/mole) in the temperature range of 600 to 700 °C, which on comparison with available diffusion data established that the growth process was interface-controlled at the higher temperatures and bulk diffusion-controlled at the lower temperatures.     

On artificial vorticity in numerical simulation of incompressible flow

For incompressible flows the addition of artificial vorticity in the vicinity of wall barriers can be useful in the numerical satisfaction of no-slip. It is shown that a method of Briley which appears to have order one error near the wall is in reality a clever means of inducing the no-slip condition through implicit addition of artificial vorticity to the calculations. This appears to explain the rapid convergence experienced by Briley's method.     

Solution of inverse dynamics problems for contour error minimization in CNC machines

For CNC machines governed by typical feedback controllers, the problem of compensating for inertia and damping of the machine axes is solved by a priori modifications to the commanded path geometry. Standard second-order models of axis dynamics are expressed in terms of the path parameter ξ rather than the time t as independent variable, incurring ordinary differential equations with polynomial coefficients. For a commanded path specified as a Pythagorean-hodograph curve R(ξ) and a P controller, a modified path $\hat{\bf R}(\xi)$ can be determined as a rational Bézier curve, that precisely compensates for the axis inertia and damping, and thus (theoretically) achieves zero contour error. For PI, PID, or P–PI controllers, exact closed-form solutions for $\hat{\bf R}(\xi)$ are no longer possible, but polynomial approximations may be computed in the numerically stable Bernstein basis on ξ?∈?[ 0,1 ]. The inverse-dynamics path modification procedure is applicable to both constant feedrates and variable feedrates defined by polynomial functions V(ξ) of the curve parameter. The method is described in the general context of PID controllers, and its implementation is then demonstrated for both P and PI controllers, governing motion along paths with extreme variations of curvature and/or parametric speed.     

Exploring the design space of reliable multicast protocols for wireless mesh networks

Many important applications in wireless mesh networks require reliable multicast communication, i.e., with 100% packet delivery ratio (PDR). Previously, numerous multicast protocols based on automatic repeat request (ARQ) have been proposed to improve the packet delivery ratio. However, these ARQ-based protocols can lead to excessive control overhead and drastically reduced throughput. In this paper, we present a comprehensive exploration of the design space for developing high-throughput, reliable multicast protocols that achieve 100% PDR.Motivated by the fact that 802.11 MAC layer broadcast, which is used by most wireless multicast protocols, offers no reliability, we first examine if better hop-by-hop reliability provided by unicasting the packets at the MAC layer can help to achieve end-to-end multicast reliability. We then turn to end-to-end solutions at the transport layer. Previously, forward error correction (FEC) techniques have been proved effective for providing reliable multicast in the Internet, by avoiding the control packet implosion and scalability problems of ARQ-based protocols. In this paper, we examine if FEC techniques can be equally effective to support reliable multicast in wireless mesh networks. We integrate four representative reliable schemes (one ARQ, one FEC, and two hybrid) originally developed for the Internet with a representative multicast protocol ODMRP and evaluate their performance.Our experimental results via extensive simulations offer an in-depth understanding of the various choices in the design space. First, compared to broadcast-based unreliable ODMRP, using unicast for per-hop transmission only offers a very small improvement in reliability under low load, but fails to improve the reliability under high load due to the significantly increased capacity requirement which leads to congestion and packet drop. Second, at the transport layer, the use of pure FEC can significantly improve the reliability, increasing PDR up to 100% in many cases, but can be inefficient in terms of the number of redundant packets transmitted. In contrast, a carefully designed ARQ–FEC hybrid protocol, such as RMDP, can also offer 100% reliability while improving the efficiency by up to 38% compared to a pure FEC scheme. To our best knowledge, this is the first in-depth study of high-throughput, reliable multicast protocols that provide 100% PDR for wireless mesh networks.     

A study on the behaviour of TLD-100 glow peaks at extreme ambient temperatures in Riyadh, Saudi Arabia

In this study, the temperature-induced variations in the TLD-100 response and the modifications in its glow peaks are investigated in real environmental exposure conditions in Riyadh, Saudi Arabia, where ambient temperatures during summer reach >45 degrees C and with relative humidity of <10%. Three groups of 12 TLD-100 cards in Harshaw type 8814 TLD cardholders were deployed as environmental dosemeters for a period of approximately 1 month for 12 consecutive months. One group was irradiated to 5 mGy 137Cs prior to deployment; another was irradiated to the same dose after deployment, while the last group was left unirradiated. Analysis of glow curves was done using commercially available glow curve deconvolution software (CGCD). Monthly variations in peak 3, 4 and 5 areas relative to the corresponding peak areas of a prompt glow curve are presented. Results of this study show good TL signal compensation between peaks 4 and 5 at all ambient temperatures encountered in this experiment, despite the observed individual variations experienced by each of these peaks. The sum of peak 4 and 5 areas is constant to within approximately 10%, for both pre- and post-irradiated dosemeters, during this 12-month cycle.     

Smart homes and their users: a systematic analysis and key challenges

Published research on smart homes and their users is growing exponentially, yet a clear understanding of who these users are and how they might use smart home technologies is missing from a field being overwhelmingly pushed by technology developers. Through a systematic analysis of peer-reviewed literature on smart homes and their users, this paper takes stock of the dominant research themes and the linkages and disconnects between them. Key findings within each of nine themes are analysed, grouped into three: (1) views of the smart home—functional, instrumental, socio-technical; (2) users and the use of the smart home—prospective users, interactions and decisions, using technologies in the home; and (3) challenges for realising the smart home—hardware and software, design, domestication. These themes are integrated into an organising framework for future research that identifies the presence or absence of cross-cutting relationships between different understandings of smart homes and their users. The usefulness of the organising framework is illustrated in relation to two major concerns—privacy and control—that have been narrowly interpreted to date, precluding deeper insights and potential solutions. Future research on smart homes and their users can benefit by exploring and developing cross-cutting relationships between the research themes identified.     

Mobolic: An automated approach to exercising mobile application GUIs using symbiosis of online testing technique and customated input generation

The increasingly prevalent use of mobile devices has raised the popularity of mobile applications. Therefore, automated testing of mobile applications has become an extremely important task. However, it is still a challenge to automatically generate tests with high coverage for mobile applications due to their specific nontrivial structure and the highly interactive nature of graphical user interfaces (GUIs). In this paper, we propose a novel automated GUI testing technique for mobile applications, namely, Mobolic. In this approach, tests with high coverage are automatically generated and executed by combining the online testing technique and customated input generation. Employing the online testing technique, Mobolic systematically explores the app GUI without falling in a loop. It generates relevant events “on the fly” that are followed by an immediate execution. In addition, involving the customated input generation, Mobolic automatically generates relevant user inputs such as user‐predefined, concrete, or random ones. We implemented Mobolic and evaluated its performance on 10 real‐world open‐source Android applications. Our experimental results show the effectiveness and efficiency of Mobolic in terms of achieved code coverage and overall exercising time.     

Novel Approach for Automatic Region of Interest and Seed Point Detection in CT Images Based on Temporal and Spatial Data

Accurately finding the region of interest is a very vital step for segmenting organs in medical image processing. We propose a novel approach of automatically identifying region of interest in Computed Tomography Image (CT) images based on temporal and spatial data . Our method is a 3 stages approach, 1) We extract organ features from the CT images by adopting the Hounsfield filter. 2)We use these filtered features and introduce our novel approach of selecting observable feature candidates by calculating contours’ area and automatically detect a seed point. 3) We use a novel approach to track the growing region changes across the CT image sequence in detecting region of interest, given a seed point as our input. We used quantitative and qualitative analysis to measure the accuracy against the given ground truth and our results presented a better performance than other generic approaches for automatic region of interest detection of organs in abdominal CT images. With the results presented in this research work, our proposed novel sequence approach method has been proven to be superior in terms of accuracy, automation and robustness.