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Ma K.,ST Electronics Satcom and Sensor Systems | Jayasuriya R.M.,ST Electronics Satcom and Sensor Systems | Siong D.R.L.C.,Defense Science and Technology Agency
IEEE Transactions on Industrial Electronics | Year: 2011

In this paper, the design and packaging of fully integrated digitally controlled microelectromechanical system (MEMS) filters with low cost, high performance, and compact size are introduced. The four-channel switched filters operating in the frequency range of 1120 GHz have been developed using MEMS technologies and four five-pole edge-coupled bandpass filters, which are modified from the traditional edge-coupled bandpass filter in the input and output feeders to achieve a better stopband performance. Microwave filters, MEMS circuits, and related packaging are investigated and demonstrated theoretically and experientially. © 2006 IEEE.


Oswal M.,Nanyang Technological University | See K.-Y.,Nanyang Technological University | Soh W.,Nanyang Technological University | Chang W.Y.,DSO National Laboratories | And 3 more authors.
2010 IEEE Electrical Design of Advanced Packaging and Systems Symposium, EDAPS 2010 | Year: 2010

This paper describes a methodology to predict farfield (FF) emissions from a high-speed board based on the fields measured in the near-field (NF) region. The NF to FF transformation is based upon an empirical relationship between the measured fields in both the NF and FF regions. Initial results show that the predicted FF emissions from a high-speed board provide the designer a good confidence on the compliance of regulatory emission limits.


Lee H.P.,National University of Singapore | Wang F.,Defense Science and Technology Agency
Computer Methods in Biomechanics and Biomedical Engineering | Year: 2010

Head trauma injury due to impact by a flying golf ball is one of the most severe possible injury accidents on the golf course. Numerical simulations based on the finite element method are presented to investigate head injury in children due to impact by a flying golf ball. The stress and energy flow patterns in a head model during the golf ball impact are computed for various combinations of striking speed, falling angle of the golf ball before impact, and impact location. It is found that a child is more prone to head injury due to golf ball impact on the frontal and side/temporal areas. The simulated results are found to conform to the clinical reports on children's head injuries from flying golf balls. © 2010 Taylor & Francis.


Ma G.,Nanyang Technological University | Zhou H.,Nanyang Technological University | Lu Y.,University of Edinburgh | Chong K.,Defense Science and Technology Agency
Engineering Structures | Year: 2010

When an underground structure is subjected to a subsurface explosion, an in-structure shock occurs. The in-structure shock can be a major cause of disruption and even damage to the instruments and equipment contained in the structure if the detonation is relatively distant. For this reason, an appropriate analysis and prediction of explosion-induced in-structure shock is an important topic in the area of protective design of underground structures. In this paper, a detailed analysis is conducted on a representative buried structural element subjected to soil-transmitted blast. The soil-structure interaction is considered by introducing an interfacial damping between the structural element and the surrounding soil. Two phases of the structural response to the blast load, i.e., a blast loading phase and a free-vibration phase, are analyzed. Based on the analytically derived time histories of the structural response, which represent the in-structure shock, the response spectra concerning the equipment (sub-structures) attached to the main structure are constructed. Besides providing a theoretical approach for the evaluation of the in-structure shock and its subsequent effects, the present analysis is supplementary to the relevant provisions in TM5-855-1 and TM5-1300, in which only rough predictions of in-structure shock for buried structures are specified. © 2010 Elsevier Ltd.


Ibekwe A.U.,Royal Dutch Shell | Pu Y.,Newcastle University | Ham W.L.,Defense Science and Technology Agency | Dow R.S.,Newcastle University
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2014

With the expectation of hull girder asymmetry and corresponding shift in elastic neutral axis resulting from collision damages and other forms of structural deteriorations, the interaction of vertical and horizontal hull girder capacities become quite significant in the assessment of ship structural safety. This paper therefore extends the application of a previously proposed interactive-numerical probabilistic based methodology for structural safety to assess the hull girder ultimate strength reliability of a damaged ship by means of a user-defined numerical framework. Hull girder capacity is calculated using the NS94D ultimate strength code, which is based on the Smith's progressive collapse method. The resulting deterministic responses have been interactively linked to the NESSUS probabilistic framework so that the reliability of the damaged hull girder is predicted using an implicit limit state function defined based on a transformation of coordinates to appropriately account for any shift in the neutral axis. Random deviations of the constituent variables are directly applied to calculate the ultimate strength deterministic responses, thereby circumventing the need to characterize any correlated strength variable, which is at best subjective. The conventional approach of characterizing ultimate strength by an assumed coefficient of variation and distribution type was found to be conservative in predicting structural safety of ships relative to the proposed method. Application of the interactive-numerical technique for structural reliability is therefore considered significant for problems involving correlated random variables with unknown statistical characteristics. The method is being considered to predict the safety of cracked hull girders by accounting for the residual strength and further load bearing capabilities of deteriorated and adjacent elements. Copyright © 2014 by ASME.

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