An analysis is presented of polyimides (PIs) exposed to heat and humidity stress over long periods. Electron spectroscopy for chemical analysis (ESCA) and Fourier transform infrared (FTIR) spectroscopy were used to in...
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An analysis is presented of polyimides (PIs) exposed to heat and humidity stress over long periods. Electron spectroscopy for chemical analysis (ESCA) and Fourier transform infrared (FTIR) spectroscopy were used to investigate the basic physical mechanisms that affect PI when stressed. The results show that changes are confined to a surface layer at the PI-air interface. ESCA data show significant changes at the PI-air interface and that the PI-Si interface remains unchanged. FTIR transmission data indicate that the bulk chemistry is unaffected by such exposure. The surface chemistry is characterized by a significant reduction in the pyromellitic dyanhydride (PMDA) moiety and changes in the bonding of oxygen. There appear to be changes in the imide structure for the PI surface, but the mechanisms of change require further study. This has reliability implications for microelectronic systems using PI as a dielectric.< >
A new single-key-lock (SKL) mechanism used for implementing the access matrix of the computer protection system is proposed. The key selection is very flexible. The lock values are generated recursively based on the N...
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A new single-key-lock (SKL) mechanism used for implementing the access matrix of the computer protection system is proposed. The key selection is very flexible. The lock values are generated recursively based on the Newton's interpolating polynomial. The insertion of a new user/file into the system can be successfully implemented without recomputing all locks/keys. [ABSTRACT FROM AUTHOR]
We report the observation of electrically induced changes in transmissivity in Fabry-Perot devices consisting of spin-cast azo-dye/polymer films deposited between gold mirrors. In poled samples the observed modulation...
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We report the observation of electrically induced changes in transmissivity in Fabry-Perot devices consisting of spin-cast azo-dye/polymer films deposited between gold mirrors. In poled samples the observed modulation shows a linear dependence on the applied modulating voltage. The ratio of the transmissivity modulation observed using incident transverse magnetic polarization to that observed using transverse electric polarization is used to demonstrate that the electrooptic effect dominates the modulation. This is, to our knowledge, the first reported use of a polymeric thin film linear electrooptic material in a Fabry-Perot structure and demonstrates the use of etalons to enhance electrooptic effects in very thin films.
This paper proposes a new ID-based cryptographic scheme for implementing public-key cryptosystem and signature. Instead of generating and publishing a public key for each user, the ID-based scheme permits each user to...
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A neural-network-based approach to decomposing surface EMG signals into a multitude of single muscle-fiber action potentials (SFAP) is presented. This decomposition is done to yield the signal forms of the SFAPs and t...
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A neural-network-based approach to decomposing surface EMG signals into a multitude of single muscle-fiber action potentials (SFAP) is presented. This decomposition is done to yield the signal forms of the SFAPs and to allow for localizing the particular SFAPs relative to the recording (surface) electrodes. The goal of this approach is to allow the physician or medical researcher to observe the waveforms of the electrical activity and to localize SFAPs below the surface of the skin in a noninvasive manner and without discomforting the patient, as is important for several neurological diagnostic purposes. The approach uses a Hopfield neural network in combination with a Kohonen network for discrimination and a conventional computer correlation algorithm.< >
Several different approaches are discussed for implementing conversations in loosely coupled distributed computer systems (DCSs). Important implementation factors considered include the control of exits of processes o...
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Several different approaches are discussed for implementing conversations in loosely coupled distributed computer systems (DCSs). Important implementation factors considered include the control of exits of processes on completion of their conversation tasks and the approach to execution of the conversation acceptance test. Two different exit control strategies, one in a synchronous manner and the other in an asynchronous manner, and three different approaches to execution of the conversation acceptance test, centralized, decentralized, and semi-centralized, are examined and compared in terms of system performance and implementation cost. The effectiveness of these execution approaches also depends on the way conversations are structured initially by program designers. Therefore, the two major types of conversation structures, name-linked recovery block and abstract data type conversations are examined to analyze which execution approaches are the most efficient for each conversation structure. These results provide guidelines for implementing conversations in loosely coupled DCSs.< >
A novel ID-based cryptographic scheme for implementing a public-key cryptosystem and signature is proposed. Instead of generating and publishing a public key for each user, the ID-based scheme permits each user to cho...
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A novel ID-based cryptographic scheme for implementing a public-key cryptosystem and signature is proposed. Instead of generating and publishing a public key for each user, the ID-based scheme permits each user to choose his/her name or network address as his/her public key. This eliminates the needs of a large public field and the exchange of private or public keys. The major advantage of the ID-based cryptosystem based on this scheme over other published ID-based cryptosystems is that the number of users can be extended to t*L users without degrading the system's security even when users conspire, where L is the number of the system's secrets, and t is the number of factors in p-1, where p is a large prime number.< >
A password authentication mechanism based on the public-key distribution cryptosystem is proposed. The scheme uses an authentication table to replace the traditional password file. With this scheme, even if the authen...
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A password authentication mechanism based on the public-key distribution cryptosystem is proposed. The scheme uses an authentication table to replace the traditional password file. With this scheme, even if the authentication table is comprised, the system security is preserved. The user's password is effectively bound to the user's identification in a timely, efficient, and simple manner.< >
We propose that short-period doping superlattices are suitable for the enhancement of a third-order susceptibility arising from free carriers in nonparabolic energy subbands. The inherent advantage lies in the ability...
We propose that short-period doping superlattices are suitable for the enhancement of a third-order susceptibility arising from free carriers in nonparabolic energy subbands. The inherent advantage lies in the ability to simply engineer the superlattice potential profile, yielding control of miniband energy dispersion. We consider short-period GaAs doping superlattices composed of uniformly doped donor and acceptor layers, and planar-doped n- and p-type monolayers separated by intrinsic regions. Calculations of the electronic structure of compensated and n-type noncompensated n-i-p-i superlattices incorporating miniband dispersion at nonzero temperature are reported. We show that small modulations of the superlattice potential lead to large subband nonparabolicities and we calculate a twentyfold improvement in the third-order susceptibility over bulk GaAs at room temperature, comparable to that predicted for GaAs/AlGaAs compositional superlattices.
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