Characterization of mechanical properties of γAl2O3 dispersed epoxy resin cured by γ‐ray radiation

Epoxy resins are widely utilized as high performance thermosetting resins for many industrial applications, but they are characterized by relatively low toughness. Incorporation of rigid inorganics is suggested to improve the mechanical properties of epoxy resins. An attempt is made to disperse nanosized γ‐Al₂O₃ particles into diglycidyl ether of bisphenol A epoxy resins for the improvement of the mechanical properties. These hybrid epoxy–alumina composites are prepared using by the γ‐ray curing technique conducted at 100 kGy under nitrogen at room temperature. The composites are characterized by determining the gel content, flexural strength, Youngis modulus, and toughness at room temperature using scanning electron microscopy and FTIR studies. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1898–1903, 2004     

Search for Barley (Hordeum vulgare L.) with higher lipid content

The search for a barley with a higher lipid content was concentrated on the USDA Barley World Conllection. Seeds of 14,000 entries were examined visually for an embryo size: total seed size ratio greater than the cultivated barley variety Prilar, and 60 entries were selected. Seeds of the 60 entries were assayed for lipid content by NMR spectroscopy, and the 7 entries with the highest oil content, along with Prilar, were prepared for further analysis. Barley lipids were solvent extracted, classified by silicic acid column chromatography, and separated by thin layer chromatography, and the fatty acid composition was determined by gas liquid chromatography. Total lipid contents of the 8 barleys ranged from 3.4% for Prilar to 4.6% for CI 12116. The seven selections had lipid contents which ranged from 9–35% higher than Prilar. Only slight qualitative differences were noted among the lipid classes of the eight barleys analyzed.     

Image-based spacecraft pointing model using single-bank dual-band registration

The growing interest in the development of small satellites and the demand for high-resolution imaging has made the pointing and drift rate requirements of a satellite more stringent. To achieve high pointing accuracy, star sensors can be used, but their size and weight are too large for small satellites. The need for keeping the overall cost of the spacecraft down and still achieve adequate pointing accuracies has provoked the development of relatively inexpensive and high-performance attitude systems that can provide competitive pointing accuracies during imaging operations. In order to realize such a system, this research describes a novel approach for finding the attitude of a satellite at any arbitrary rotation by using inter-band offsets from a single multi-spectral imager (MSI). For Earth observational imagery, UK Disaster Monitoring Constellation Earth-pointing MSI is used. This research focuses on the potential use of a narrow angle between the bands of a pushbroom sensor for determining the attitude of a spacecraft. The technique investigated does not require ground control points or knowledge of any ground features, but rather estimates the orientation of the platform through analysis of perspective and timing-based distortions between images. These distortions are assumed translational and affine in nature, with two-dimensional shifts being extracted from imagery using a Singular Value Decomposition-based registration scheme. In order to better understand the effect of attitude on imagery, a model was developed for predicting inter-band shifts given an attitude. This was then used to estimate the shifts between imagery at nominal attitude and given a series of simulated manoeuvres. Several simulations have shown that the row and column offsets represented a straight line. Hence, we expressed the row and column shifts in terms of straight line parameters. These geometric attributes are then represented in terms of Euler axis/angle to find the mapping for the elements of the general rotation matrix. Once the mapping is computed for the elements of the rotation matrix, we used the standard equations to determine the angle of rotation and Euler axis. The accuracy of attitude estimates depends on the magnitude of angular separation between the cameras, orientation of spacecraft, sensor resolution, image texture, and image registration method. The technique proposed in this study may however be applied to any satellite with pushbroom sensors that have a discernable along track separation and sufficient overlap.     

Milepost GCC: Machine Learning Enabled Self-tuning Compiler

Tuning compiler optimizations for rapidly evolving hardware makes porting and extending an optimizing compiler for each new platform extremely challenging. Iterative optimization is a popular approach to adapting programs to a new architecture automatically using feedback-directed compilation. However, the large number of evaluations required for each program has prevented iterative compilation from widespread take-up in production compilers. Machine learning has been proposed to tune optimizations across programs systematically but is currently limited to a few transformations, long training phases and critically lacks publicly released, stable tools. Our approach is to develop a modular, extensible, self-tuning optimization infrastructure to automatically learn the best optimizations across multiple programs and architectures based on the correlation between program features, run-time behavior and optimizations. In this paper we describe Milepost GCC, the first publicly-available open-source machine learning-based compiler. It consists of an Interactive Compilation Interface (ICI) and plugins to extract program features and exchange optimization data with the cTuning.org open public repository. It automatically adapts the internal optimization heuristic at function-level granularity to improve execution time, code size and compilation time of a new program on a given architecture. Part of the MILEPOST technology together with low-level ICI-inspired plugin framework is now included in the mainline GCC. We developed machine learning plugins based on probabilistic and transductive approaches to predict good combinations of optimizations. Our preliminary experimental results show that it is possible to automatically reduce the execution time of individual MiBench programs, some by more than a factor of 2, while also improving compilation time and code size. On average we are able to reduce the execution time of the MiBench benchmark suite by 11% for the ARC reconfigurable processor. We also present a realistic multi-objective optimization scenario for Berkeley DB library using Milepost GCC and improve execution time by approximately 17%, while reducing compilation time and code size by 12% and 7% respectively on Intel Xeon processor.     

Projection‐based head‐tracking 3‐D displays

Abstract— This paper describes the construction and operation of four 3‐D displays in which each display produces two images for each eye and thus fits into the category of projection‐based binocular stereoscopic displays. The four 3‐D displays described are pico‐projector‐based, liquid‐ crystal—on—silicon (LCOS) conventional projector‐based, 120‐Hz digital‐light‐processor (DLP) projector‐ based, and the HELIUM3D system. In the first three displays, images are produced on a direct‐view LCD whose conventional backlight is replaced with a projection illumination source that is controlled by a multi‐user head tracker; novel steering optics direct the projector output to regions referred to as exit pupils located at the viewers' eyes. In the HELIUM3D display, the image information is supplied by a horizontally scanned, fast, light valve whose output is controlled by a spatial light modulator (SLM) to direct images to the appropriate viewers' eyes. The current statu s and the multimodal potential of the HELIUM3D display are described.     

A sub goal seeking approach for reactive navigation in complex unknown environments

Reactive-based approaches are widely used in autonomous navigation. However, in complex unknown environments, pure reactive-based navigation still poses a few challenges since it can be easily trapped by a local minimum and may produce some extra manoeuvres. This paper presents the design of a reactive-based approach for navigation in complex and unknown environments called sub goal seeking, in which depth point maps of the environment are analysed to extract free spaces around the robot. These spaces are then evaluated the one that is most likely to lead to the final goal is chosen as a sub goal. The robot then drives towards these sub goals, instead of the final goal until it is visible. By analysing the environmental structure, dead-ends within robot sensory range are able to be detected thus reducing the chance of being trapped and also reducing unnecessary manoeuvres. This paper also evaluates the performance of the sub goal seeking approach using three criteria, goal achievable ability, safety and maneuvering through extensive simulation and real mobile robot experiments.     

Building personalised synthetic voices for individuals with severe speech impairment

For individuals with severe speech impairment accurate spoken communication can be difficult and require considerable effort. Some may choose to use a voice output communication aid (or VOCA) to support their spoken communication needs. A VOCA typically takes input from the user through a keyboard or switch-based interface and produces spoken output using either synthesised or recorded speech. The type and number of synthetic voices that can be accessed with a VOCA is often limited and this has been implicated as a factor for rejection of the devices. Therefore, there is a need to be able to provide voices that are more appropriate and acceptable for users.This paper reports on a study that utilises recent advances in speech synthesis to produce personalised synthetic voices for 3 speakers with mild to severe dysarthria, one of the most common speech disorders. Using a statistical parametric approach to synthesis, an average voice trained on data from several unimpaired speakers was adapted using recordings of the impaired speech of 3 dysarthric speakers. By careful selection of the speech data and the model parameters, several exemplar voices were produced for each speaker. A qualitative evaluation was conducted with the speakers and listeners who were familiar with the speaker. The evaluation showed that for one of the 3 speakers a voice could be created which conveyed many of his personal characteristics, such as regional identity, sex and age.     

Security monitoring in heterogeneous globally distributed environments

Keeping control of a highly heterogeneous network of distributed systems in any global company is a difficult task. This problem cannot be brought under control with any single approach or technology. We must focus on the objectives and build tools into a common integrated framework to provide a security state and event monitoring concept for the entire organisation.     

Characterization of the effects of β‐carotene on the thermal oxidation of triacylglycerols using HPLC‐ESI‐MS

RP HPLC method coupled to ESI‐MS was used for the analysis and characterization of the oxidation of model triacylglycerols (TAGs) in presence of β‐carotene. β‐Carotene was added to the TAGs and oxidized in the Rancimat at 110°C. The samples were separated isocratically using a mixture of isopropanol with methanol and a Phenomenex C18 column. β‐Carotene degradation was measured using high performance TLC. We found that β‐carotene plays an important role during the thermal degradation of high oleic acid model TAGs. Half of the β‐carotene was degraded before 3 h of thermal treatment. β‐Carotene significantly increases the peroxide value of the TAGs after the third hour, suggesting a pro‐oxidant action. However, different TAGs show different activity toward thermal treatment and β‐carotene. The LLL was found to be less stable, OLL and OLO were stable till 10 and 12 h respectively, while POO, OOO, and OSO were the stable TAGs till 14 h. In TAGs, replacing linoleic acid by oleic acid, the stability of the corresponding TAG was found to increase by 2 h. A new class of oxidized TAGs was reported for the first time, together with previously reported species. The proposed mechanism of formation and identification of the newly identified species have been explained. Among the oxidized species of TAGs, mono‐hydroperoxides, bis‐hydroperoxides, epoxy‐epidioxides, and epoxides were the major compounds identified.     

用于热管理的散热铜柱凸点

当接近热源时，任何设备的主动冷却都是最有效的。今天一切先进的中央处理单元（CPU）和图形处理器（GPU）都采用倒装芯片的封装形式，其焊料凸点直接放在芯片中较活跃的区域。一种新的方法已经可以将热活性物质集成在这些焊料凸点中，尤其是铜柱凸点。当热电材料放在封装中，性能系数（COP），或者说散去的功率与可散功率之比一般为1左右；但若该材料被放置在凸点中，则性能系数可达4、6或8。这为电子行业中非常令人困扰的热问题提供了十分具有吸引力的解决方案。