Proportional Topology Optimization: A new non-gradient method for solving stress constrained and minimum compliance problems and its implementation in MATLAB

A new topology optimization method called the Proportional Topology Optimization (PTO) is presented. As a non-gradient method, PTO is simple to understand, easy to implement, and is also efficient and accurate at the same time. It is implemented into two MATLAB programs to solve the stress constrained and minimum compliance problems. Descriptions of the algorithm and computer programs are provided in detail. The method is applied to solve three numerical examples for both types of problems. The method shows comparable efficiency and accuracy with an existing gradient optimality criteria method. Also, the PTO stress constrained algorithm and minimum compliance algorithm are compared by feeding output from one algorithm to the other in an alternative manner, where the former yields lower maximum stress and volume fraction but higher compliance compared to the latter. Advantages and disadvantages of the proposed method and future works are discussed. The computer programs are self-contained and publicly shared in the website www.ptomethod.org.Comment: 18 pages, 8 figures, and 2 appendices (MATLAB codes

Myrtaceae, a cache of fungal biodiversity

Twenty-six species of microfungi are treated, the majority of which are associated with leaf spots of Corymbia, Eucalyptus and Syzygium spp. (Myrtaceae). The treated species include three new genera, Bagadiella, Foliocryphia and Pseudoramichloridium, 20 new species and one new combination. Novelties on Eucalyptus include: Antennariella placitae, Bagadiella lunata, Cladoriella rubrigena, C. paleospora, Cyphellophora eucalypti, Elsinoë eucalypticola, Foliocryphia eucalypti, Leptoxyphium madagascariense, Neofabraea eucalypti, Polyscytalum algarvense, Quambalaria simpsonii, Selenophoma australiensis, Sphaceloma tectificae, Strelitziana australiensis and Zeloasperisporium eucalyptorum. Stylaspergillus synanamorphs are reported for two species of Parasympodiella, P. eucalypti sp. nov. and P. elongata, while Blastacervulus eucalypti, Minimedusa obcoronata and Sydowia eucalypti are described from culture. Furthermore, Penidiella corymbia and Pseudoramichloridium henryi are newly described on Corymbia, Pseudocercospora palleobrunnea on Syzygium and Rachicladosporium americanum on leaf litter. To facilitate species identification, as well as determine phylogenetic relationships, DNA sequence data were generated from the internal transcribed spacers (ITS1, 5.8S nrDNA, ITS2) and the 28S nrDNA (LSU) regions of all taxa studie

Verification of a localization criterion for several disordered media

We analytically compute a localization criterion in double scattering approximation for a set of dielectric spheres or perfectly conducting disks uniformly distributed in a spatial volume which can be either spherical or layered. For every disordered medium, we numerically investigate a localization criterion, and examine the influence of the system parameters on the wavelength localization domains.Comment: 30 pages, LateX, amstex, revtex styles, 20 figure

A slip model for micro/nano gas flows induced by body forces

A slip model for gas flows in micro/nano-channels induced by external body forces is derived based on Maxwell's collision theory between gas molecules and the wall. The model modifies the relationship between slip velocity and velocity gradient at the walls by introducing a new parameter in addition to the classic Tangential Momentum Accommodation Coefficient. Three-dimensional Molecular Dynamics simulations of helium gas flows under uniform body force field between copper flat walls with different channel height are used to validate the model and to determine this new parameter

Collaborative Development of Open Educational Resources for Open and Distance Learning

Open and distance learning (ODL) is mostly characterised by the up front development of self study educational resources that have to be paid for over time through use with larger student cohorts (typically in the hundreds per annum) than for conventional face to face classes. This different level of up front investment in educational resources, and increasing pressures to utilise more expensive formats such as rich media, means that collaborative development is necessary to firstly make use of diverse professional skills and secondly to defray these costs across institutions. The Open University (OU) has over 40 years of experience of using multi professional course teams to develop courses; of working with a wide range of other institutions to develop educational resources; and of licensing use of its educational resources to other HEIs. Many of these arrangements require formal contracts to work properly and clearly identify IPR and partner responsibilities. With the emergence of open educational resources (OER) through the use of open licences, the OU and other institutions has now been able to experiment with new ways of collaborating on the development of educational resources that are not so dependent on tight legal contracts because each partner is effectively granting rights to the others to use the educational resources they supply through the open licensing (Lane, 2011; Van Dorp and Lane, 2011). This set of case studies examines the many different collaborative models used for developing and using educational resources and explain how open licensing is making it easier to share the effort involved in developing educational resources between institutions as well as how it may enable new institutions to be able to start up open and distance learning programmes more easily and at less initial cost. Thus it looks at three initiatives involving people from the OU (namely TESSA, LECH-e, openED2.0) and contrasts these with the Peer-2-Peer University and the OER University as exemplars of how OER may change some of the fundamental features of open and distance learning in a Web 2.0 world. It concludes that while there may be multiple reasons and models for collaborating on the development of educational resources the very openness provided by the open licensing aligns both with general academic values and practice but also with well established principles of open innovation in businesses

Accent on communication: the impact of regional and foreign accent on comprehension in adults with aphasia

PURPOSE: This study explored whether an unfamiliar non-native accent, differing in both segmental and prosodic features was more difficult for individuals with aphasia to understand than an unfamiliar native accent, which differed in segmental features only. METHOD: Comprehension, which was determined by accuracy judgments on true/false sentences, and speed of response were assessed in the following three conditions: a familiar Southern Standard British English (SSBE) accent, an unfamiliar native Grimsby accent, and an unfamiliar non-native Chinese accent. Thirty-four English speaking adults (17 people with and 17 people without aphasia) served as listeners for this study. RESULTS: All listeners made significantly more errors in the unfamiliar non-native accent, although this difficulty was more marked for those with aphasia. While there was no affect of speaker accent on the response times of listeners with aphasia, listeners without aphasia were significantly slower with the unfamiliar non-native accent. CONCLUSION: The results indicate that non-native accented speech affects comprehension even on simple tasks in ideal listening conditions. The findings suggest that speaker accent, especially accents varying in both segmental and prosodic features, can be a barrier to successful interactions between non-native accented speakers and native listeners, particularly those with aphasia. IMPLICATIONS FOR REHABILITATION: Aphasia is an acquired language disorder, often occurring after stroke, which affects an individual’s understanding and use of language. People with and without aphasia find an unfamiliar accent more difficult to understand than a familiar accent, and these problems are more significant for those with aphasia. Problems are greater when the accent differs from the familiar accent by both individual sounds and prosody. Health professionals need to be aware that their accent is likely to affect an individual’s performance on assessments as well as their understanding of information, and could consider the use of other mediums to present information (e.g. drawing) and minimizing other variables that might compromise comprehension (e.g. background noise)

A Modified Distortion Measurement Algorithm for Shape Coding

Efficient encoding of object boundaries has become increasingly prominent in areas such as content-based storage and retrieval, studio and television post-production facilities, mobile communications and other real-time multimedia applications. The way distortion between the actual and approximated shapes is measured however, has a major impact upon the quality of the shape coding algorithms. In existing shape coding methods, the distortion measure do not generate an actual distortion value, so this paper proposes a new distortion measure, called a modified distortion measure for shape coding (DMSC) which incorporates an actual perceptual distance. The performance of the Operational Rate Distortion optimal algorithm [1] incorporating DMSC has been empirically evaluated upon a number of different natural and synthetic arbitrary shapes. Both qualitative and quantitative results confirm the superior results in comparison with the ORD lgorithm for all test shapes, without any increase in computational complexity

Phyllosticta citriasiana sp. nov., the cause of Citrus tan spot of Citrus maxima in Asia

Guignardia citricarpa, the causal agent of Citrus Black Spot, is subject to phytosanitary legislation in the European Union and the U.S.A. This species is frequently confused with G. mangiferae, which is a non-pathogenic, and is commonly isolated as an endophyte from citrus fruits and a wide range of other hosts. Recently, necrotic spots similar to those caused by G. citricarpa were observed on fruit of Citrus maxima intercepted in consignments exported from Asia. In these spots, pycnidia and conidia of a Guignardia species closely resembling G. citricarpa were observed, and therefore measures were taken for the consignments in line with the European Union legislation for G. citricarpa. To determine the identity of the causal organism on this new host, fungal isolates were subjected to DNA sequence analysis of the internal transcribed spacer region (ITS1, 5.8S, ITS2), translation elongation factor 1-alpha (TEF1) and actin genes. A combined phylogenetic tree resolved three species correlating to G. citricarpa, G. mangiferae and a previously undescribed species, Phyllosticta citriasiana sp. nov., closely related to G. citricarpa. Morphologically P. citriasiana can be distinguished from G. citricarpa by having larger conidia, longer conidial appendages, and in not producing any diffuse yellow pigment when cultivated on oatmeal agar (OA). Furthermore, it is distinguishable from G. mangiferae by having smaller conidia, with a narrower mucoid sheath. In culture, colonies of P. citriasiana can also be distinguished from G. citricarpa and G. mangiferae by being darker shades of grey and black on OA, malt extract agar (MEA), potato-dextrose agar, and cornmeal agar. Furthermore, cultures of P. citriasiana achieved optimal growth after 2 weeks at 21-27°C, and ceased to grow at 30-33°C. In contrast, colonies of G. citricarpa and G. mangiferae achieved optimal growth at 27-30°C, and ceased to grow at 30-36°C Colonies of P. citriasiana also grew faster than those of G. citricarpa and G. mangiferae on OA and MEA. Phyllosticta citriasiana appears to be a harmful pathogen of Citrus maxima, causing a tan spot on fruit, underlining the need for further surveys and research to determine its distribution and host range