137 research outputs found
Mechanisms beneath rectangular shallow foundations on sands: vertical loading
No full textThis paper details analysis of deformation behaviour of silica and carbonate sands under a rectangular foundation subject to uniaxial vertical load based on results from a series of centrifuge model tests. A multiscale Particle Image Velocimetry/Digital Image Correlation (PIV/DIC) technique was used to record and analyse the foundation tests with high resolution and measurement precision. Cone penetrometer and pressuremeter tests provide in situ soil characterisation of the tested sand sample in the centrifuge environment. The soil behaviour is analysed through foundation load-settlement response and the observed soil deformation measurements. Different soil deformation mechanisms and strain behaviours were observed in the different sands tested, and particle shape effect is considered, with data from scanning electron microscopy, to explain the differences. The results and analyses contribute towards better understanding of different soil behaviours under shallow foundations in different sands
Synchronised multi-scale image analysis of soil deformations
No full textNew apparatus and techniques for performing synchronised multi-scale particle image velocimetry or digital image correlation (PIV/DIC) soil deformation measurements have been developed. A central camera records a full field of view (FoV) of the model capturing the ‘macro’ deformation mechanism and the boundaries of the model. Simultaneously, an adjacent slave camera records a subset of the full FoV capturing the ‘micro’ soil response in a region of special interest, such as under the corner of footing. The ‘micro’ FoV images have higher resolution in terms of particle/pixel size ratio (d/p), resulting in the ability to measure localised deformations that are invisible to lower resolution images. Recommendations are made with respect to appropriate subset size and spacing for highresolution images. A photogrammetric correction process requiring a small number of static control points is proposed and the performance is validated against a conventional photogrammetric calibration utilising a large array of static control points. Lastly, results from a validation experiment are presented comparing the PIV/DIC output from the ‘macro’ and ‘micro’ FoV, illustrating that: (a) the photogrammetric correction method proposed is robust and (b) that there has been an improvement in spatial resolution of the strain measurements that can be obtained through the ‘micro’ FoV camera.</p
Numerical investigation of oblique detonation waves on a truncated cone in hydrogen-air mixtures
No full textTraditional methods of initiating oblique detonation waves (ODWs) using wedges and cones face a fundamental challenge in reconciling the need for rapid initiation with stable combustion, especially at low flight Mach numbers (Ma < 8). This study introduces an innovative initiation configuration involving a truncated cone. By utilizing Euler equations coupled with detailed hydrogen-air chemical reaction models, the wave dynamics induced by the truncated cone configuration are systematically explored. The findings reveal that the truncated cone configuration enables more rapid initiation of ODWs compared to conventional cones, while also preserving improved stability when contrasted with wedge. This behavior can be attributed to the planar flow characteristics in the post-shock field of truncated cone, generated by the upstream wedge-shaped shock, and the Taylor-Maccoll flow characteristics, caused by the downstream conical shock. Furthermore, the study delves into the initiation and morphological changes with respect to the inner radius and angle of the truncated cone. As inner radii or truncated cone angle increase, three initiation wave systems emerge: stable, oscillatory, and detached modes. Analysis of the dynamic variations in pressure and velocity within the induction zone highlights that the upstream oscillation originates from the flow velocity in the induction zone falling below the local Chapman-Jouguet velocity of normal detonation wave (NDW). However, the upstream region of the truncated cone exhibits more pronounced expansion effects, leading to momentum loss, and subsequently, the weakening and even vanishing of the NDW. This prompts the downstream oscillation of the initiation structure, instigating a cyclic oscillation pattern
Statistical analysis plan for the second INTEnsive blood pressure Reduction in Acute Cerebral hemorrhage Trial (INTERACT2): a large-scale investigation to solve longstanding controversy over the most appropriate management of elevated blood pressure in the hyperacute phase of intracerebral hemorrhage
No full textCraig Anderson, Emma Heeley, Stephane Heritier, Hisatomi Arima, Mark Woodward, Richard Lindley, Bruce Neal, Yining Huang, Ji-Guang Wang, Mark Parsons, Christian Stapf, Tom Robinson, Pablo Lavados, Candice Delcourt, Stephen Davis, and John Chalmers for the INTERACT2 Investigator
Increasing interpretability in XAI: Addressing the design principles for interactive XUIs to increase interpretability in XAI for end-users
No full textRecent advancements in artificial intelligence (AI), particularly in deep learning, have significantly enhanced AI capabilities but have also led to more complex and less interpretable algorithms. This research addresses the challenge of Explainable AI (XAI) by focusing on enhancing the interpretability of AI decisions through the use of Explainable User Interfaces (XUI). The study identifies two primary knowledge gaps: the predominance of XAI research targeting technically skilled users, neglecting the end-user who often lacks technical expertise, and the insufficient exploration of user-centric design principles in real-world XUI applications.The research adopts the Design Science Research Method (DSRM) to develop an XUI tailored for the FOKUS project, which uses Electrocardiogram (ECG) data to detect myocardial infarctions. The study emphasises the strategic application of interactive design principles such as complementary naturalness, flexibility in explanation methods, and responsiveness through progressive disclosure to improve the system’s interpretability. Notably, sensitivity to context and mind, though not initially implemented, emerged as a critical design principle from the analysis and was subsequently positioned at the pinnacle of a restructured pyramid model of design principles.Key findings highlight the effectiveness of the selected design principles in enhancing interpretability and underscore the importance of involving stakeholders early in the development process to align the XAI and XUI with end-user needs. The research proposes a structured design approach framework for XUI, involving sequential phases from pre-XAI to XUI design, to systematically integrate user feedback and improve the design iteratively. The proposed framework restructured pyramid model of the design principles aim to guide future developments in XAI and XUI, enhancing their practical application and effectiveness in various contexts.Management of Technology (MoT
Early Carboniferous high-silica granites in the Kalejun Mountains, Chinese western Tianshan: Petrogenesis, tectonic setting and geodynamic implications for the South Tianshan Ocean
No full textEarly Carboniferous granitoids, distributed in the Yining and Central Tianshan blocks, Chinese western Tianshan, are important for deciphering their tectonic contexts and evolutionary history of the South Tianshan Ocean. Here we present LA-ICP-MS zircon U-Pb ages, in situ Hf isotopic data, and whole-rock geochemical data of the monzogranites and syenogranites from the Kalejun Mountains, southern part of the Yining Block, aiming to constrain their petrogenesis and geodynamic background. The results reveal that these monzogranites and syenogranites were emplaced at 356 Ma and 344 Ma, respectively. Geochemically, they are characterized by high SiO2 (68.74–75.76 wt.%) and K2O (4.58–6.18 wt%), low MgO (0.14–0.76 wt.%) and P2O5 (0.04–0.24 wt.%) contents. In addition, they are depleted in Ba, Sr, Eu, Ti, Nb, and Zr, and enriched in Rb, Cs, Th, and U. These features indicate that the Kalejun granites are high-silica I-type granites. The low positive εHf(t) values (+1.1 to +8.2) and old TDM2Hf model ages (1294 to 827 Ma) of the studied zircons imply that the parental magma of these granites were derived from the reworking of Proterozoic basement with minor involvement of juvenile materials. Combined with the Late Devonian to Early Carboniferous magmatic activities in the Yining and Central Tianshan blocks (e.g. the discovery of A-type bubble rhyolites and high-Mg andesites), it is suggested that the Kalejun granites were likely related to the roll-back of the South Tianshan oceanic slab. Finally, we argue that the subduction of South Tianshan Ocean probably terminated at the end of the Early Carboniferous.</p
Montgomery County Outdoor Classroom and Learning Landscape Conceptual Master Plan
No full textThe Izaak Walton League (IWL) is a national organization "formed in 1922 to save outdoor America for future generations. The League's founders, who were avid anglers, chose to name the organization after Izaak Walton, the 17th century author of The Complete Angler, one of the most famous books on fishing. The IWL is one of the earliest conservation organizations to set an aggressive course to defend wild America by changing public policy. Almost every major, successful conservation program that America has in place today can be traced directly to a League activity or initiative.Throughout more than 270 communities, IWL chapters advance the mission of the organization - restoring watersheds, reducing air pollution, fighting litter, protecting wildlife habitat and open spaces, and instilling conservation ethics in outdoor recreationists." (http://www.iwla.org/index.php?id=9).In line with this mission, the Christiansburg-Montgomery Chapter of the IWL has initiated a partnership with the Montgomery County Public School System (MCPS) to utilize portions of their site as a county-wide outdoor classroom. The site's central location in the county as well as its existing resources and opportunities make it an excellent site for watershed education. Here county teachers can engage their students in hands-on learning opportunities and instill a love of and appreciation for the natural environment, particularly watersheds and fishing. Some key site attributes include a spring, a fish run, two ponds, a stream, a wetland area, and a small trail system. Site habitat areas include wetland, meadow, stream, spring, pond, and wooded hillslope.The Community Design Assistance Center, an outreach Center in the College of Architecture and Urban Studies, was asked to assist Montgomery County Public Schools in preparing a conceptual site master plan for the site. The conceptual master plan looks to enhance safe and ADA accessible access to site resources and develop additional learning opportunities on site as well. Support facilities and structures such as ADA restrooms, adequate bus turn-arounds, parking, and storage are also addressed.Virginia. Department of EducationLearn & Serve GrantCover title."Prepared for the Montgomery County Public School System and the Christiansburg-Montgomery Izaak Walton League Chapter, June 1010."Project team: Elizabeth Gilboy, director; Kim Steika, project coordinator; Daniel (Yu) Ling, Yining Xu
Architecture Design of High Safety Helicopter Flight Control System with Direct Control Mode
No full textExperience of Parameter Optimization of the High-Cycle Accumulation Model for Undrained Triaxial Tests on Sand
No full textAnalysis of Failure Mechanisms in Silica and Carbonate Sands Beneath a Strip Foundation Under Vertical Loading
No full textThis paper reports the deformation behavior of silica and carbonate sands under a strip foundation subjected to uniaxial vertical load. Small-scale physical modelling tests of a strip surface foundation under vertical load were conducted in a geotechnical centrifuge and Particle Image Velocimetry/Digital Image Correlation (PIV/DIC) was used to analyze images of an exposed plane of the model beneath the foundation to visualize the failure mechanisms. The observed mechanisms are interpreted in conjunction with load-settlement response and cone penetrometer resistance profiles. The failure mechanisms are illustrated through normalized vertical and horizontal displacement fields and shear and volumetric strain fields derived from the PIV analysis. Different soil deformation mechanisms and load-settlement responses were observed in the different sands. Soil resistance profiles measured using a miniature cone penetrometer do not correlate with the measured foundation bearing resistance and an interpretation of particle shape effect is introduced to explain the differing behaviors. The results presented improve understanding of the different responses in carbonate sands and silica sand beneath a shallow foundation under vertical load.</jats:p
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