18,304 research outputs found
Attenuation performance of a semi-active Helmholtz resonator in a grazing flow duct
No full textAuthor name used in this publication: Mak, Cheuk Ming2012-2013 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishedC
Prediction of flow noise from in-duct spoilers using computational fluid dynamics
No full textThis paper presents a method for the prediction of flow noise from in-duct spoilers using Computational Fluid Dynamics (CFD). Previous work conducted by Mak [Mak CM. A prediction method for aerodynamic sound produced by multiple elements in air ducts. J Sound Vib 2005;287:395-403] and Mak et al. [Mak CM, Wu J, Ye C, Yang J. Flow noise from spoilers in ducts. J Acoust Soc Am 2009;125:3756-65] provides a method for such a prediction based on experimental data. In this work, the advanced Large-eddy Simulation turbulence model (LES) is used to compute the mean pressure drop across spoilers and the fluctuating drag forces acting on them. The predictions of the numerical simulation agree well with those based on experimental data and the actual, measured levels. With the aid of CFD simulation, engineers are now able to use the prediction method developed by the authors to predict the flow noise from in-duct spoilers using the LES turbulence model.Department of Building Services Engineerin
Mak Ko island (Thailand), palms
No full textGoh Mak, Interior and Southern Coast; Amphur Laem Ngop, Changwat Trat. Nov. 28, 1936. Panatomic Proms. Rollerflex. L Br. Granular clay. 0-100 cm. 5.6 1/25 -.GrayscalePendleton nitrate negative, Box 189 of 38
The politics and economics of regulatory impact assessment
No full textThis is the author accepted manuscript. The final version is available from the publisher via the link in this record
Application of computational fluid dynamics to the study of designed green features for sustainable buildings
No full text2009-2010 > Academic research: refereed > Chapter in an edited book (author)Version of RecordPublishedC
Phase Distribution Efficiency of cm-Scale Ultrasonically Powered Receivers
No full textIn the domain of ultrasonically powered biomedical implants, there is an increasing interest in cm-scale ultrasonic receivers (RX). However, when a single-element transducer is used as the RX transducer, an uneven phase distribution across the RX area can significantly reduce the harvestable power. In this paper, we investigate the impact of lateral and angular misalignment on the acoustic field phase distribution across the RX surface. We show that, for a single-element RX transducer, lateral misalignment has minimal effect on the harvestable power, whereas even small angular misalignments can cause a considerable reduction, especially for larger RX sizes. We present a potential solution that consists of subdividing a large RX transducer (e.g. 20 × 20mm2) into smaller elements, which significantly improves power transfer efficiency by taking advantage of the smaller phase variation across the surface of each element. The trade-offs between achieving a minimum acceptable power transfer efficiency and managing the increased complexity in packaging and matching circuitry are also discussed.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 MaterialsBio-Electronic
Highly efficient laser-driven Compton gamma-ray source
No full textThe recent advancement of high-intensity lasers has made all-optical Compton scattering become a promising way to produce ultrashort brilliant gamma-rays in an ultra-compact system. However, so far achieved Compton gamma-ray sources are limited by low conversion efficiency and spectral intensity. Here we present a highly efficient gamma photon emitter obtained by irradiating a high-intensity laser pulse on a miniature plasma device consisting of a plasma lens and a plasma mirror. This concept exploits strong spatiotemporal laser-shaping process and high-charge electron acceleration process in the plasma lens, as well as an efficient nonlinear Compton scattering process enabled by the plasma mirror. Our full three-dimensional particle-in-cell simulations demonstrate that in this novel scheme, brilliant gamma-rays with very high conversion efficiency (higher than 10(-2)) and spectral intensity (similar to 10(9) photons/0.1%BW) can be achieved by employing currently available petawatt-class lasers with intensity of 10(21) W cm(-2). Such efficient and intense gamma-ray sources would find applications in wide-ranging areas. ©2019 The Author(s)
Compte rendu de « Overlapping Cosmologies in Asia : Transcultural and Interdisciplinary Approaches » / edited by M. Mak Bill and Eric Huntington
No full textOverlapping Cosmologies in Asia : Transcultural and Interdisciplinary Approaches / edited by M. Mak Bill and Eric Huntington. – Leiden : Brill, 2022. – xviii + 297 p. – (Crossroads : History of Interactions across the Silk Routes ; 4). – 1 vol. relié de 16 × 24 cm. – 128,40 €. – isbn 978-90-04-51141-5
Perancangan Alat Pengasapan Ikan Ergonomis Berbasis Antropometri dengan Simulasi Desain Menggunakan Software Autodesk Fusion pada UMKM Mak Kum Kendal
No full textUMKM Ikan Asap Mak Kum memproduksi ikan asap di Kendal, Jawa Tengah. Proses pengasapan yang masih dilakukan secara tradisional dengan peralatan sederhana menyebabkan hasil yang tidak konsisten, baik dari segi rasa, warna, maupun tekstur. Selain itu, pekerja mengalami keluhan fisik akibat paparan panas, dan kondisi cuaca lembap menghambat aliran asap, mengurangi efisiensi pengasapan. Oleh karena itu diperlukan alat pengasapan ikan yang lebih efisien, ergonomis, dan mampu meningkatkan kapasitas produksi. Penelitian ini bertujuan untuk merancang alat pengasapan ikan dengan kapasitas lebih besar, pengurangan asap berlebih, serta dilengkapi dengan tuas rotasi untuk mempermudah pekerja. Metode yang digunakan dalam penelitian ini yaitu pendekatan antropometri untuk menentukan dimensi yang ergonomis dan dilakukan simulasi alat menggunakan software Autodesk Fusion untuk menguji kekuatan dan ketahanan struktur alat. Hasil rancangan alat pengasapan ikan UMKM Mak Kum memiliki dimensi tinggi 162 cm, kedudukan rak 104 cm, lebar 61 cm, dan panjang 110 cm, dengan kapasitas rak dari 47 menjadi 78 potong per proses. Pada simulasi analisis tegangan menunjukkan tegangan maksimum 0,4852 Mpa, simulasi perpindahan menunjukkan pergeseran maksimum 0,0039 mm, dan simulasi faktor keamanan dengan nilai 15. Berdasarkan simulasi faktor keamanan dihasilkan warna biru tua yang berarti rangka tersebut aman untuk dibebani gaya sebesar 300 N
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