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A Study on Improve Share Image of Visual Cryptography
Chao-Ming Wu,Wen-Jan Chen,Yu-Yen Shen 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7
The visual cryptography is a method of encrypt secret image in to two or several share images and use the mankind's visual scheme to decipher. The sizes of the two share images produced by our method will be different. So, the transmission bandwidth and storage space needed are less than the traditional visual cryptography system. In addition the security of the data is increased.
A Study of Optical Properties of InGaAs/GaAs Quantum Dots
Gwo-Jen Jan,Chih-Ming Lai,Fu-Yu Chang,Hao-Hsing Lin 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.III
The optical properties of InGaAs/GaAs quantum dots (QDs) were investigated by temperature-dependent photoluminescence (PL) and photoreflectance (PR) spectroscopies. The surface morphology and structure analysis of InGaAs QDs were also examined and characterized by a field emission scanning electron microscope (SEM) and an atomic force microscope (AFM). The In$_{0.5}$Ga$_{0.5}$As/GaAs self-assembled QDs specimens were grown with gas-source molecular beam epitaxy and migration enhanced techniques. The area density of the QDs is on an order of magnitude about 1 $\times$ 10$^{10}$ dots/cm$^2$. The measured PL results exhibited 5 major energy peaks, two of which are attributed to InGaAs QDs, one is attributed to the InGaAs wetting layer and the other two are attributed to GaAs band-gap transitions. Two of the low energy features are identified to the optical transitions of the ground state. They were originated from the two kinds of InGaAs QDs which might be formed with slight change of the indium composition. An inverted ``S curve'' shape of the temperature-dependent PL peak energies was observed. This abnormal behavior of the line-shape is attributed to carrier localization. The results of PR measurement which reveal energy features on the high energy side contributed by GaAs is also reported.
Development of a full-scale magnetorheological damper model for open-loop cable vibration control
Ru Zhang,Yi-Qing Ni,Yuanfeng Duan,Jan-Ming Ko 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.23 No.6
Modeling of magnetorheological (MR) dampers for cable vibration control to facilitate the design of even more effective and economical systems is still a challenging task. In this study, a parameter-adaptive three-element model is first established for a full-scale MR damper based on laboratory tests. The parameters of the model are represented by a set of empirical formulae in terms of displacement amplitude, voltage input, and excitation frequency. The model is then incorporated into the governing equation of cable-damper system for investigation of open-loop vibration control of stay cables in a cable-stayed bridge. The concept of optimal voltage/current input achieving the maximum damping for the system is put forward and verified. Multi-mode suboptimal and Single-mode optimal open-loop control method is then developed. Important conclusions are drawn on application issues and unique characteristics of open-loop cable vibration control using MR dampers.
Design formulas for vibration control of sagged cables using passive MR dampers
Yuanfeng Duan,Yi-Qing Ni,Hongmei Zhang,Billie F. Jr. Spencer,Jan-Ming Ko,Shenghao Dong 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.23 No.6
In this paper, a method for analyzing the damping performance of stay cables incorporating magnetorheological (MR) dampers in the passive control mode is developed taking into account the cable sag and inclination, the damper coefficient, stiffness and mass, and the stiffness of damper support. Both numerical and asymptotic solutions are obtained from complex modal analysis. With the asymptotic solution, analytical formulas that evaluate the equivalent damping ratio of the sagged cable-damper system in consideration of all the above parameters are derived. The main thrust of the present study is to develop an general design formula and a universal curve for the optimal design of MR dampers for adjustable passive control of sagged cables. Two sag-affecting coefficients are derived to reflect the effects of cable sag on the maximum attainable damping ratio and the optimal damper coefficient. For the cable configurations commonly used in cable-stayed bridges, the sag-affecting coefficients are directly expressed in terms of the sag-extensibility parameter to facilitate the control design. A case study on adjustable passive vibration control of the longest cable (536 m) on Stonecutters Bridge is carried out to demonstrate the influence of the sag for the damper design, and to figure out the necessity of adjustability of damper coefficients for achieving maximum damping ratio for different vibration modes.
Terminology of metal-organic frameworks and coordination polymers (IUPAC Recommendations 2013)
Batten, Stuart R.,Champness, Neil R.,Chen, Xiao-Ming,Garcia-Martinez, Javier,Kitagawa, Susumu,Ö,hrströ,m, Lars,O’Keeffe, Michael,Paik Suh, Myunghyun,Reedijk, Jan De Gruyter 2013 Pure and applied chemistry. Vol.85 No.8
<P>A set of terms, definitions, and recommendations is provided for use in the classification of coordination polymers, networks, and metal–organic frameworks (MOFs). A hierarchical terminology is recommended in which the most general term is coordination polymer. Coordination networks are a subset of coordination polymers and MOFs a further subset of coordination networks. One of the criteria an MOF needs to fulfill is that it contains potential voids, but no physical measurements of porosity or other properties are demanded per se. The use of topology and topology descriptors to enhance the description of crystal structures of MOFs and 3D-coordination polymers is furthermore strongly recommended.</P>
Design formulas for vibration control of taut cables using passive MR dampers
Yuanfeng Duan,Yi-Qing Ni,Hongmei Zhang,Billie. F., Jr. Spencer,Jan-Ming Ko,Yi Fang 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.23 No.6
Using magnetorheological (MR) dampers in multiswitch open-loop control mode has been shown to be cost-effective for cable vibration mitigation. In this paper, a method for analyzing the damping performance of taut cables incorporating MR dampers in open-loop control mode is developed considering the effects of damping coefficient, damper stiffness, damper mass, and stiffness of the damper support. Making use of a three-element model of MR dampers and complex modal analysis, both numerical and asymptotic solutions are obtained. An analytical expression is obtained from the asymptotic solution to evaluate the equivalent damping ratio of the cable-damper system in the open-loop control mode. The individual and combined effects of the damping coefficient, damper stiffness, damper mass and stiffness of damper support on vibration control effectiveness are investigated in detail. The main thrust of the present study is to derive a general formula explicitly relating the normalized system damping ratio and the normalized damper parameters in consideration of all concerned effects, which can be easily used for the design of MR dampers to achieve optimal open-loop vibration control of taut cables.