980 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
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Novel fuzzy logic controllers with self-tuning capability
No full textTwo controllers which extend the PD+I fuzzy logic controller to deal with the plant having time varying nonlinear dynamics are proposed. The adaptation ability of the first self tuning PD+I fuzzy logic controller (STPD+I_31) is achieved by adjusting the output scaling factor automatically thereby contributing to significant improvement in performance. Second controller (STPD+I_9) is the simplified version of STPD+I_31 which is designed under the imposed constraint that allows only minimum number of rules in the rule bases. The proposed controllers are compared with two classical nonlinear controllers: the pole placement self tuning PID controller and sliding mode controller. All the controllers are applied to the two-links revolute robot for the tracking control. The tracking performance of STPD+I_31 and STPD+I_9 are much better than the pole placement self tuning PID controller during high speed motions while the performance are comparable at low and medium speed. In addition, STPD+I_31 and STPD+I_9 outperform sliding mode controller using same method of comparison study
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
Division and Unity: The History and Historiography of the Pennsylvania Constitution
No full textAbout the author:
Wen Li Teng is pursuing a double major in History and Political Science at the University of Chicago
The Menkaure Triad, Numerical Thinking, and Divine Configurations in Ancient Egypt
No full textAbout the Author
Formerly an undergraduate at the University of California, Los Angeles, Wen Li Teng is a transfer student at the University of Chicago. Wen Li is currently pursuing a major in History
Civilization and Nature: A Reading of Ancient Texts
No full textAbout the Author
Hailing from Singapore, Wen Li Teng is a first-year student at the University of California, Los Angeles. She intends to declare a major in History
The Advances in Conversion Techniques in Triboelectric Energy Harvesting: A Review
No full textA triboelectric nanogenerator (TENG) is a new transducer utilizing contact electrification and electrostatic induction to transform mechanical energy into electric energy. Due to its high energy density and flexibility, it can be employed to make electronic devices self-powered by harvesting ambient mechanical energy in many application scenarios, such as biomedical devices, wearable electronics, and Internet-of-Things (IoT) sensors. However, due to the time-varying and low internal capacitance of a TENG, it is challenging to extract electrical energy from it. Hence, good power conversion techniques are crucial in TENG energy harvesting systems. Currently, studies on dedicated integrated power conversion techniques are very limited. Due to the exponentially increasing research interests in TENG, a comprehensive study on the TENG energy harvesting system, emphasizing integrated-circuit (IC) power conversion techniques, is urgently needed. This paper summarizes and compares the state-of-the-art triboelectric energy harvesting systems, focusing on different power conversion techniques for output power enhancement. Some techniques, which have been widely used in other relevant energy harvesting systems, are also mentioned to inspire innovative design strategies for TENG systems.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and MaterialsElectronic Instrumentatio
A CRITICAL REVIEW ON THE MATERIAL ASPECTS OF TRIBOELECTRIC NANOGENERATORS (TENG)
No full textTriboelectric nanogenerators (TENG) take the advantage of coupling effect for harvesting energy in the area of electronics for various self-powered applications. These nanogenerators are capable of converting energy in our surroundings into electrical energy by using the process of electrostatic induction and contact electrification. Triboelectric layers of a TENG are formed basically with the use of various polymers, metals and other inorganic materials like PTFE (Poly tetra fluoro ethylene), PDMS (polydimethyl siloxane), FEP (Fluorinated ethylene propylene) and Kapton. Selection of different materials for the device fabrication is very important since it contribute towards the triboelectric effect and also forms the fundamental structure for the proposed TENG device. In this review article, we emphasis mainly on various triboelectric materials considering factors such as stability, flexibility, power density etc., to improve upon the electrical output of the devices for different applications
[[alternative]]Semantics and Pedagogical Grammar of verb-particles in Modern Chinese
No full text[[abstract]]This thesis intends to analyze and sub-divide nine verb-particles in Modern Chinese. Teng (1977) first pointed out the core meanings of verb-particles and established the framework of verb-particles in Chinese. When “上(shang4)、下(xia4)、起(qi3)、出(chu1)、開(kai1)、到(dao4)、走(zou3)、掉(diao4)、住(zhu4) ” are placed after verbs and their semantics have grammaticalized, they present the force from motion-through-location. Furthermore, as the meanings of verb-particles are varied and indistinct, it is very difficult for learners to distinguish nuances of each one. According to Bolinger (1971), the semantics of a verb-particle derive from the original meanings of the word and are limited by both verbs and objects. After sub-dividing the nine verb-particles, this thesis seeks to establish some principles for the pedagogical grammar of verb-particles in Modern Chinese and suggests some ideas for teaching.
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