Search

An overhead crane transports cargoes of various weights and volumes depending on the operation case. Friction factors characterized by damped coefficients are changeable in terms of the operating environment. In this study, an adaptive version of the sliding mode control of a crane system is developed in the case of no priori knowledge of the payload mass and damped elements. Using two inputs, namely, trolley driving force and cargo lifting force, the proposed adaptive robust controller simultaneously executes four duties, including tracking the trolley, hoisting the cargo, keeping the cargo swing small during transient state, and completely eliminating the payload angle at steady destination. Numerical simulations and experiments are conducted to investigate the quality of the proposed controller. The results show that the proposed controller works well and all system responses are asymptotically stabilized. [ABSTRACT FROM AUTHOR]

Abstract: This study consists of two parts: mathematical modeling for the start-up period (transient system) and an optimum design analysis of a thermoelectric cooler (TEC). In the mathematical modeling for the transient system, a dimensionless time to reach the steady state is determined, which can be practically adopted to reduce the start-up period during the operation of a thermoelectric module (TEM). The objectives of the optimum design analysis are to investigate the effect of key parameters characterizing the TEC on the coefficient of performance (COP) and to determine the optimal conditions for the TEC design. It is found that the COP increases up to 44% with an increase of the ratio of heat transfer area of the insulator to that of the TEM, γ. For micro-TEC, the COP is significantly affected by the TEM depth and spacer. Especially in the case of TEM depth of 100 μm, the COP is enhanced up to 110% at an optimal spacer depth ratio () of 10. The results show that the effect of figure of merit on the COP appears differently according to the combination of thermal conductance , electric resistance R and Seebeck constant S of the TEM. It reveals that when a new thermoelectric material is developed, the optimal combination among , and S as well as Zm should be considered simultaneously. [Copyright &y& Elsevier]

This paper presents direct visualization of uptake directionality for cell-membrane impermeant fluorescent molecules and fluorescence-doped nanoparticles at a single-cell level during electroporation. To observe directly the uptake direction, we used microchannel-type electroporation that can generate a relatively symmetric and uniform electric field. For all the image frames during electroporation, fluorescence intensities that occurred at cell membranes in both uptake directions toward the electrodes have been sequentially recorded and quantitatively analyzed pixel by pixel. In our experiments, we found that fluorescent molecules, even not labeled to target biomolecules, had their own uptake direction with different intensities. It is also observed that the uptake intensity toward the cell membrane had a maximal value at a certain electric voltage, not at the highest value of voltages applied. The results also imply that the uptake direction of fluorescence-doped nanoparticles can be determined by a net surface charge of uptake materials and sizes in the electroporative environments. In summary, we performed a quantitative screening and direct visualization of uptake directionality for a set of fluorescent molecules and fluorescence-doped nanoparticles using electric-pulsation. Taking a closer look at the uptake direction of exogenous materials will help researchers to understand an unknown uptake phenomenon in which way foreign materials are inclined to move, and furthermore to design functional nanoparticles for electroporative gene delivery.