New Efficient Technique for Finite Element Modeling of Macro Fiber Composite Piezoelectric Materials

A lot of interest to simulate piezocomposite actuators with finite element method has been increased recently. However, there are still open questions regarding the modeling methodology, accuracy, and computational time cost. In this work, a new technique for modeling macro fiber composite piezoelectric actuator by finite element analysis is proposed. The presented technique models the piezocomposite actuator as a simple monolithic piezoceramic material with just two electrodes along its longitudinal extremes instead of using the actual large number of electrodes which results in very fine finite element mesh with high computational time cost. The proposed technique is validated successfully by comparing its results with those of the actual detailed model as well as with the published experimental results and manufacturer’s data.

Monitoring Coastal Reclamation Subsidence in Hong Kong with Distributed Scatterer Interferometry

Land subsidence has been a significant problem in land reclaimed from the sea, and it is usually characterized by a differential settlement pattern due to locally unconsolidated marine sediments and fill materials. Time series Synthetic Aperture Radar Interferometry (InSAR) techniques based on distributed scatterers (DS), which can identify sufficient measurement points (MPs) when point-wise radar targets are lacking, have great potential to measure such differential reclamation settlement. However, the computational time cost has been the main drawback of current distributed scatterer interferometry(DSI) for its applications compared to the standard PSI analysis. In this paper, we adopted an improved DSI processing strategy for a fast and robust analysis of land subsidence in reclaimed regions, which is characterized by an integration of fast statistically homogeneous pixel selection based (FaSHPS-based) DS detection and eigendecomposition phase optimization. We demonstrate the advantages of the proposed DSI strategy in computational efficiency and deformation estimation reliability by applying it to two TerraSAR-X image data stacks from 2008 to 2009 to retrieve land subsidence over two typical reclaimed regions of Hong Kong International Airport (HKIA) and Hong Kong Science Park (HKSP). Compared with the state-of-the-art DSI methods, the proposed strategy significantly improves the computational efficiency, which is enhanced approximately 30 times in DS identification and 20 times in phase optimization. On average, the DSI strategy results in 7.8 and 3.7 times the detected number of MPs for HKIA and HKSP with respect to persistent scatter interferometry (PSI), which enables a very detailed characterization of locally differential settlement patterns. Moreover, the DSI-derived results agree well with the levelling survey measurements at HKIA, with a mean difference of 1.87 mm/yr and a standard deviation of 2.08 mm/yr. The results demonstrate that the proposed DSI strategy is effective at improving target density, accuracy and efficiency in monitoring ground deformation, particularly over reclaimed coastal areas.

An Innovative Time-Cost-Quality Tradeoff Modeling of Building Construction Project Based on Resource Allocation

The time, quality, and cost are three important but contradictive objectives in a building construction project. It is a tough challenge for project managers to optimize them since they are different parameters. This paper presents a time-cost-quality optimization model that enables managers to optimize multiobjectives. The model is from the project breakdown structure method where task resources in a construction project are divided into a series of activities and further into construction labors, materials, equipment, and administration. The resources utilized in a construction activity would eventually determine its construction time, cost, and quality, and a complex time-cost-quality trade-off model is finally generated based on correlations between construction activities. A genetic algorithm tool is applied in the model to solve the comprehensive nonlinear time-cost-quality problems. Building of a three-storey house is an example to illustrate the implementation of the model, demonstrate its advantages in optimizing trade-off of construction time, cost, and quality, and help make a winning decision in construction practices. The computational time-cost-quality curves in visual graphics from the case study prove traditional cost-time assumptions reasonable and also prove this time-cost-quality trade-off model sophisticated.

A FPGA implementation of solder paste deposit on printed circuit boards error detector based in a bright and contrast algorithm

Solder paste deposit on printed circuit boards (PCB) is a critical stage. It is known that about 60% of functionality defects in this type of boards are due to poor solder paste printing. These defects can be diminished by means of automatic optical inspection of this printing. Actually, this process is implemented by image processing software with its inherent high computational time cost. In this paper we propose to implement a high parallel degree image comparison algorithm suitable to be implemented on FPGA, which could be incorporated to an automatic inspection system. The hardware implementation of the algorithm allows us to fulfill time requirements demanded by industry.

A Study on Topological Optimization of Structure Using Cantor Function As Teaching Function

In order to obtain better structural designs, it is important to carry out optimization from primary parts of those designs. Especially, designs of topologies of structures were depended on intuition of the designers and they were not always best fitted to the requirements of the structure. These days, designs of topologies of the structures become important to meet those purposes. In this study, we will propose a new method to obtain optimum topology of the structure to satisfy their requirements by growth and degeneration tutored by Cantor function as teaching function. Cantor function is the one which is very famous as an introduction of the fractal. By operating its order, it is very easy to manipulate its division among 0 and 1. We set skipping and restarting rules of growth and degeneration, and criteria of convergence. We applied the proposed method to the problem similar to the one well-known as Mitchell truss problem to compare the results obtained by the proposed method. From these numerical examples, we can obtain quite similar topological results to the homogenization method in small number of iteration. There, the proposed method has advantages in computational time, cost and memory. More over, we can see the growth of the topology. Although we demonstrate the proposed method in a few examples, we can say that the proposed method can derive optimum oriented topology even with this simple scheme efficiently.