Output-only modal identification by in-operation modal appropriation for use with enhanced frequency domain decomposition method

Journal of Mechanical Science and Technology - Output-only modal identification or operational modal analysis (OMA) has gained increasing popularity in many fields of engineering. In the context of...     

An integrated optimisation for the weight,the structural performance and the cost of composite structures

An integrated optimisation methodology is proposed to optimise the manufacturing cost as well as the structural performance and the weight of composite laminated plates manufactured by the resin transfer moulding (RTM) process. In the present approach, the fibre type, the number of fabrics, the layer stacking sequence and the fibre volume fraction are optimised to minimise the structural weight and the material cost of composite structure under the stiffness constraint and the mould filling time constraint which is a part of process cycle time. With the results obtained, it is investigated how the weight and the material cost are traded-off. The optimisation methodology suggests a guide to cost-effective material selection in the preliminary conceptual design stage.     

Physicochemical characterization and adsorptive properties of some Moroccan clay minerals extruded as lab-scale monoliths

Textural, structural and adsorptive properties of some Moroccan clays were investigated. The minerals were used as raw material for extrusion of honeycomb monoliths. Adsorption and desorption tests were performed with selected model pollutants such as volatile organic compounds (VOCs). The clays have been chosen, apart from their abundance and price, on the basis of successful extrusion as integral lab-scale honeycomb monoliths. The obtained monoliths have been subjected to measurements of the mechanical strength.     

An online approach for multi-sprite generation based on camera parameters estimation

We propose in this work to synthesize online the visual content of a complex video into multiple sprites, while detecting on-the-fly each sprite’s limits. For each received frame, physically meaningful camera rotation angles and focal lengths are firstly estimated from frame-to-sprite homography. These physical parameters are then used by a thresholding-based assignment stage to confirm whether the frame can be added without distortions on one of the sprites that have been built up to that instant. In this case, the selected sprite will be updated online accordingly by applying direct frame-to-sprite warping and advanced median blending of only the newly discovered background content. Else, a new sprite must be defined while selecting the current frame as a reference frame. Extensive experiments accomplished on challenging videos demonstrate that the proposed approach can process online a long video while preventing accumulation of alignment errors.     

Screening of four vascular aquatic plants for uptake of monosodium methanearsonate (MSMA)

The post-emergent herbicide, MSMA, is used extensively for weed control in non-edible crops and for chemical mowing along roadside rights-of-way. Herbicide may gain access to adjacent water bodies by accidental application or by runoff from sprayed plots. This study utilized floating and rooted plant species in hydroponic solution to monitor the uptake of trace levels of the herbicide from an aqueous concentration of 24 μg/ml. Plant species evaluated included Eichhornia crassipes, Alternanthera philoxeroides, Hydrophila lacustris and Lemna minor. Plants were analyzed for total arsenic over the 6 weeks of study using the silver diethyldithiocarbamate (SDDC) procedure. Bioaccumulation ratios were then determined for each plant species.     

String Matching Over Compressed Text on Handheld Devices Using Tagged Sub-Optimal Code (TSC)

This paper presents Tagged Sub-optimal code (TSC), a new coding technique to speed up string matching over compressed databases on personal digital assistants (PDA). TSC is a variable-length sub-optimal code that supports minimal prefix property. It always determines its codeword boundary without traversing a tree or lookup table. TSC technique may be beneficial in many types of applications: speeding up string matching over compressed text, and speeding decoding process. This paper also presents two algorithms for string matching over compressed text using TSC (SCTT) and the Byte Pair Encoding (BPE) technique (SCTB). indent Several experiments were conducted to compare the performance of TSC, Byte Pair Encoding (BPE), and Huffman code. Several PDA databases with different record sizes were used: the well-known Calgary dataset and a set of small-sized PDA databases. Experimental results show that SCTT is almost twice as fast as the Huffman-based algorithm. SCTT has also the same performance in search time as the search in uncompressed databases and is faster than the SCTB algorithm. For frequently updated PDA databases such as phone books, to-do list, and memos, SCTT is the recommended method regardless of the size of the average record length, since the time required to compress the updated records using BPE poses significant delays compared to TSC.Abdeghani Bellaachia is an associate professor at the Computer Science Department, George Washington University. He received his Diploma of Engineering from Mohammadia School of Engineering in Rabat, Morocco, in 1983, the MS and Doctoral of Science degrees from the George Washington University in 1992. He was the chief architect of the Arabization of the Palm-OS platform. His research interests include data mining, multi-lingual information retrieval systems, cross-language retrieval systems, database management systems, bio-informatics, design and analysis of algorithms, handheld computing, and parallel processing.Iehab AL Rassan works for Ministry of higher education in Saudi Arabia, director of information technology department. He received his B.A. in Computer Information Systems from King Faisal University. He then received his M.S. in Computer Science from Fairleigh Dickinson University and his Doctor of Science in Computer Science from the George Washington University. His research interests include coding theories, information retrieval, string-matching algorithms, data compression, and handheld computing.