Automatic generation of robot and manual assembly plans using octrees

This paper aims to investigate automatic assembly planning for robot and manual assembly. The octree decomposition technique is applied to approximate CAD models with an octree representation which are then used to generate robot and manual assembly plans. An assembly planning system able to generate assembly plans was developed to build these prototype models. Octree decomposition is an effective assembly planning tool. Assembly plans can automatically be generated for robot and manual assembly using octree models. Research limitations/implications - One disadvantage of the octree decomposition technique is that it approximates a part model with cubes instead of using the actual model. This limits its use and applications when complex assemblies must be planned, but in the context of prototyping can allow a rough component to be formed which can later be finished by hand. Assembly plans can be generated using octree decomposition, however, new algorithms must be developed to overcome its limitations

Patient-reported outcome measures for chronic obstructive pulmonary disease: the exclusion of people with low literacy skills and learning disabilities

<p>Background: Patient-reported outcome measures (PROMs) are intended to reflect outcomes relevant to patients. They are increasingly used for healthcare quality improvement. To produce valid measures, patients should be involved in the development process but it is unclear whether this usually includes people with low literacy skills or learning disabilities. This potential exclusion raises concerns about whether these groups will be able to use these measures and participate in quality improvement practices.</p> <p>Methods: Taking PROMs for chronic obstructive pulmonary disease (COPD) as an exemplar condition, our review determined the inclusion of people with low literacy skills and learning disabilities in research developing, validating, and using 12 PROMs for COPD patients. The studies included in our review were based on those identified in two existing systematic reviews and our update of this search. Results People with low literacy skills and/or learning disabilities were excluded from the development of PROMs in two ways: explicitly through the participant eligibility criteria and, more commonly, implicitly through recruitment or administration methods that would require high-level reading and cognitive abilities. None of the studies mentioned efforts to include people with low literacy skills or learning disabilities.</p> <p>Conclusion: Our findings suggest that people with low literacy skills or learning disabilities are left out of the development of PROMs. Given that implicit exclusion was most common, researchers and those who administer PROMs may not even be aware of this problem. Without effort to improve inclusion, unequal quality improvement practices may become embedded in the health system.</p&gt

Octree-based production of near net shape components

Near net shape (NNS) manufacturing refers to the production of products that require a finishing operation of some kind. NNS manufacturing is important because it enables a significant reduction in: machining work, raw material usage, production time, and energy consumption. This paper presents an integrated system for the production of near net shape components based on the Octree decomposition of 3-D models. The Octree representation is used to automatically decompose and approximate the 3-D models, and to generate the robot instructions required to create assemblies of blocks secured by adhesive. Not only is the system capable of producing shapes of variable precision and complexity (including overhanging or reentrant shapes) from a variety of materials, but it also requires no production tooling (e.g., molds, dies, jigs, or fixtures). This paper details how a number of well-known Octree algorithms for subdivision, neighbor findings, and tree traversal have been modified to support this novel application. This paper ends by reporting the construction of two mechanical components in the prototype cell, and discussing the overall feasibility of the system

The Analysis of design and manufacturing tasks using haptic and immersive VR - Some case studies

The use of virtual reality in interactive design and manufacture has been researched extensively but the practical application of this technology in industry is still very much in its infancy. This is surprising as one would have expected that, after some 30 years of research commercial applications of interactive design or manufacturing planning and analysis would be widespread throughout the product design domain. One of the major but less well known advantages of VR technology is that logging the user gives a great deal of rich data which can be used to automatically generate designs or manufacturing instructions, analyse design and manufacturing tasks, map engineering processes and, tentatively, acquire expert knowledge. The authors feel that the benefits of VR in these areas have not been fully disseminated to the wider industrial community and - with the advent of cheaper PC-based VR solutions - perhaps a wider appreciation of the capabilities of this type of technology may encourage companies to adopt VR solutions for some of their product design processes. With this in mind, this paper will describe in detail applications of haptics in assembly demonstrating how user task logging can lead to the analysis of design and manufacturing tasks at a level of detail not previously possible as well as giving usable engineering outputs. The haptic 3D VR study involves the use of a Phantom and 3D system to analyse and compare this technology against real-world user performance. This work demonstrates that the detailed logging of tasks in a virtual environment gives considerable potential for understanding how virtual tasks can be mapped onto their real world equivalent as well as showing how haptic process plans can be generated in a similar manner to the conduit design and assembly planning HMD VR tool reported in PART A. The paper concludes with a view as to how the authors feel that the use of VR systems in product design and manufacturing should evolve in order to enable the industrial adoption of this technology in the future

The role of institutional and family embeddedness in the failure of Sub-Saharan African migrant family businesses

There is considerable interest among European politicians and policymakers in how to integrate migrants in the local and national economy. Drawing on in-depth qualitative interviews with 20 owners of Sub-Saharan African migrant family businesses (SSAMBs) in the United Kingdom, this article critically examines why SSAMBs fail or underperform. This investigation draws upon three streams of literature – notably migrant business failure, institutional theory and family embeddedness. The findings highlight the challenges of doing business and the reasons for business failure among this group. These are different from other small businesses and include culture, family interference and ethnicity. The main contribution of the article lies in the development of a conceptual model that highlights the relationships between institutional contexts and migrant family business outcomes. The model proposes that institution and family embeddedness results in the enactment of ethnic behaviours that drive migrant businesses into cultural markets leading to business underperformance or failure

Testing and validating the CERES-wheat (Crop Estimation through Resource and Environment Synthesis-wheat) model in diverse environments

CERES-Wheat is a computer simulation model of the growth, development, and yield of spring and winter wheat. It was designed to be used in any location throughout the world where wheat can be grown. The model is written in Fortran 77, operates on a daily time stop, and runs on a range of computer systems from microcomputers to mainframes. Two versions of the model were developed: one, CERES-Wheat, assumes nitrogen to be nonlimiting; in the other, CERES-Wheat-N, the effects of nitrogen deficiency are simulated. The report provides the comparisons of simulations and measurements of about 350 wheat data sets collected from throughout the world

Establishing Consensus Core Criteria for the Protection of Heritage Trees

M.A

A Comparison of Human Decomposition in an Indoor and an Outdoor Environment

In the medicolegal context, forensic anthropologists assist investigators by gathering information from skeletal remains. While humans decompose in both indoor and outdoor environments, little research has been performed on the differences in the decomposition rate and process between subjects in an indoor environment and subjects in an outdoor environment. Limited accessibility to appropriate facilities for a comparison study between indoor and outdoor decomposition rates has prevented such research from being attempted. Documented through daily notes and photographs, six human subjects were observed from the fresh to the end of the bloat stages of decomposition. Three subjects were placed in an indoor structure. The other three decomposed in an outdoor environment. All subjects were compared to determine if decomposition rates differed between the indoor and outdoor subjects. From September 2004 through July 2005, six unembalmed, unautopsied human bodies were observed at the Anthropology Research Facility in Knoxville, Tennessee. The indoor structure was heated in winter and air conditioned during the fall. The air conditioner was broken throughout the spring/summer months. Decomposition rates were compared across seven variables and three stages using accumulated degree days (ADD). ADD was calculated for each subject using weather data gathered from an indoor/outdoor thermometer installed in the indoor structure. In the spring, summer, and fall months, indoor subjects decomposed faster than outdoor subjects. During the winter months, the indoor subject decomposed faster. Further research is necessary to determine the exact source of the differences in decomposition rates

Multiple differences in calling songs and other traits between solitary and gregarious Mormon crickets from allopatric mtDNA clades

The Linnaean Society, The British Ecological Society, The Russell Trust (St. Andrews), The Orthopterists' Society and an NSERC (Canada) grant to DTG. Gordon S. Brown provided assistance with digital imaging and morphological measurements.Background: In acoustic species, traits such as male calling song are likely to diverge quickly between allopatric populations due to sexual selection, and divergence in parameters such as carrier frequency, chirp structure, and other important song characters can influence sexual isolation. Here we make use of two forms of Mormon crickets to examine differences in a broad suite of traits that have the potential to influence speciation via sexual isolation. Mormon crickets in "gregarious" populations aggregate into dense migratory bands, and females are the sexually competitive Fsex ( sex- role reversal). There is also a non-outbreak "solitary" form. These two forms are largely but not perfectly correlated with a significant mtDNA subdivision within the species that is thought to have arisen in allopatry. Combined information about multiple, independently evolving traits, such as morphology and structural and behavioural differences in calling song, provides greater resolution of the overall differences between these allopatric populations, and allows us to assess their stage of divergence. We test two predictions, first that the forms differ in song and second that gregarious males are more reluctant to sing than solitary males due to sex role reversal. We also tested for a difference in the relationship between the size of the forewing resonator, the mirror, and carrier frequency, as most models of sound production in crickets indicate that mirror size should predict carrier frequency. Results: Multivariate analyses showed that solitary and gregarious individuals from different populations representing the two mtDNA clades had almost non-overlapping distributions based on multiple song and morphological measurements. Carrier frequency differed between the two, and gregarious males were more reluctant to sing overall. Mirror size predicted carrier frequency; however, the relationship between mirror size and surface area varied between solitary and gregarious forms, suggesting that factors above and beyond mirror size contribute to carrier frequency. Conclusion: The two clades of Mormon crickets differ in a broad suite of independent traits that probably justify subspecies status ( the two can successfully mate so may not be reproductively isolated). However, our results emphasize the importance of carefully distinguishing the ultimate causation of differences between traits used to delineate species or subspecies boundaries.Publisher PDFPeer reviewe

Spin-dependent transport in a quasiballistic quantum wire

We describe the transport properties of a 5 $\mu$m long one-dimensional (1D) quantum wire. Reduction of conductance plateaux due to the introduction of weakly disorder scattering are observed. In an in-plane magnetic field, we observe spin-splitting of the reduced conductance steps. Our experimental results provide evidence that deviation from conductance quantisation is very small for electrons with spin parallel and is about 1/3 for electrons with spin anti-parallel. Moreover, in a high in-plane magnetic field, a spin-polarised 1D channel shows a plateau-like structure close to $0.3 \times e^2/h$ which strengthens with {\em increasing} temperatures. It is suggested that these results arise from the combination of disorder and the electron-electron interactions in the 1D electron gas.Comment: 4 pages, 5 figures, latex to be published in Phys. Rev. B (15/3/2000