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Abstract. Piezoelectric energy harvesting has advantages over other alternative sources due to its large power density, ease of applications, and capability to be fabricated at different scales: macro, micro, and nano. This paper presents an electromechanical-traffic model for roadway compression-based piezoelectric energy harvesting system. A twodegree-of-freedom (2-DOF) electromechanical model has been developed for the piezoelectric energy harvesting unit to define its performance in power generation under a number of external excitations on road surface. Lead Zirconate Titanate (PZT-5H) is selected as the piezoelectric material to be used in this paper due to its high Piezoelectric Charge Constant (d) and Piezoelectric Voltage Constant (g) values. The main source of vibration energy that has been considered in this paper is the moving vehicle on the road. The effect of various frequencies on possible generated power caused by different vibration characteristics of moving vehicle has been studied. A single unit of circle-shape Piezoelectric Cymbal Transducer (PCT) with diameter of 32 mm and thickness of 0.3 mm be able to generate about 0.12 mW and 13 mW of electric power under 4 Hz and 20 Hz of excitation, respectively. The estimated power to be generated for multiple arrays of PCT is approximately 150 kW/ km. Thus, the developed electromechanical-traffic model has enormous potential to be used in estimating the macro scale of roadway power generation system.

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Performance optimization in very-large-scale integration (VLSI) design is the key success in today's design automation methodologies. One of the performance issues is the interconnect delay in deep sub-micron VLSI circuits. The interconnect delay becomes more dominant compared to gate delay when the size of the gates is reduced. This paper presents an algorithm to optimize the timing performance of the routing tree under obstacle constraints. It is known that simultaneous routing and buffer insertion is proven to be NP-complete while the two-step approach may produce a poor solution. Therefore, we propose a hybrid algorithm that can modify a given routing tree simultaneously with buffer insertion. This paper describes this algorithm and we present experimental results that show the proposed algorithm can improve the timing of the routing tree significantly with low execution time.

This paper demonstrates a simple and cost-effective bio-energy generation through biochemical reaction between yeast and sugar. Correlation of energy released between baker yeast Saccharomyces cerevisiae concentration and sugar solution concentration can be observed significantly over laboratory works. A certain number of electrons is released during the process of ethanol fermentation, in which sugars are broken down into ethanol and carbon dioxide. Consequently, bio-energy can be captured via two copper rods during the fermentation period from different concentration variables using the principle of microbial fuel cell (MFC). In this case, yeast and sugar have been selected as the concentration variables. The experiment works concluded that higher concentration of sugar solution correlates to the increment of energy output. However, the concentration of sugar beyond 0.6g/ml causes instability of the energy output. At the same time, another considerable limiting factor of the energy output is the area of separation membrane. The overabundance of sugar concentration can lead to adverse effects in harvesting the bio-energy.