giáng ya - Academia.edu (original) (raw)

Related Authors

Woontack Woo

Woontack Woo

Korea Advanced Institute of Science and Technology

Mohammed Fahim

g pan

Hellenic Open University

Willy Susilo

Uploads

Papers by giáng ya

Research paper thumbnail of A Flexible Trust-Based Access Control Mechanism for Security and Privacy Enhancement in Ubiquitous Systems

It is the ubiquity and mobility absolutely necessary for ubiquitous computing environments that r... more It is the ubiquity and mobility absolutely necessary for ubiquitous computing environments that raise new challenges for pervasive service provision invisibly. Particularly, mobility of users/devices causes unpredefined and unpredictable changes in physical location and in available resources and services, event at runtime and during the same service session, thus forcing us to consider very dynamic aspects of evaluation when designing an access control mechanism. Alternatively, there is generally no a priori trust relationship among entities interacting in pervasive computing environments which makes it essential to establish trust from scratch. This task becomes extremely challenging when it is simultaneously necessary to protect the privacy of the users involved. In this paper * , we first show how trust evaluation process of the user's system can be based on previous accesses and peer recommendations. A solution then relied on trust to control access is proposed that depends upon pre-defined access control security policy. Several tuning parameters and options are suggested so that end-users can customize to meet the security and privacy requirement of a ubiquitous system.

Research paper thumbnail of Realization and simulation of rocket multiple ignition system based on fuzzy control air-pasty

Aiming at the limited problem of multiple ignition time interval for pasty propellant rocket, pla... more Aiming at the limited problem of multiple ignition time interval for pasty propellant rocket, plasma ignition plan was proposed. Based on working process of plasma multiple ignitions, fuzzy control system was designed accordingly. On the base of electronic performance of plasma arc, the design of fuzzy controller was introduced in detail, and status recognition, control and detection of the whole ignition process was realized. Simulation of Matlab and semi-physical experimental simulation were performed. Results show the fuzzy controller has good control property. The purpose of design was attained.

Research paper thumbnail of A configuration for future giant telescope

Chinese Astronomy and Astrophysics, 2004

A configuration for the Future Giant Telescope is proposed. It is a 30 m telescope with segmented... more A configuration for the Future Giant Telescope is proposed. It is a 30 m telescope with segmented primary mirror and alt-azimuth mounting. The aspherical f/1.2 primary mirror is made up of 1095 partial annular submirrors. The optical system includes a Nasmyth system, a coud6 system and a wide field system. The Nasmyth system has a novel design with four mirrors and provides a ,~10 arcmin field of diffraction-limited images, a much larger field than can be obtained by the traditional Nasmyth system. Several diffractionlimited observations each over a small field, can be carried out simultaneously. By applying active optics to change the shape, tip, tilt and piston of the submirrors, thereby to effect a new aspherical surface of the primary, excellent quality images can be obtained for the coud4 system and the wide field system. The wide field system has a field of 25 arcmin, the focal surface is only slightly curved and the atmospheric dispersion could be corrected. The tolerances of the surface shape and position for the submirrors, and the telescope mounting and structure are also discussed. The innovations in this configuration should have a general significance for future giant telescopes.

Research paper thumbnail of Du lich sinh thai

Research paper thumbnail of A Flexible Trust-Based Access Control Mechanism for Security and Privacy Enhancement in Ubiquitous Systems

It is the ubiquity and mobility absolutely necessary for ubiquitous computing environments that r... more It is the ubiquity and mobility absolutely necessary for ubiquitous computing environments that raise new challenges for pervasive service provision invisibly. Particularly, mobility of users/devices causes unpredefined and unpredictable changes in physical location and in available resources and services, event at runtime and during the same service session, thus forcing us to consider very dynamic aspects of evaluation when designing an access control mechanism. Alternatively, there is generally no a priori trust relationship among entities interacting in pervasive computing environments which makes it essential to establish trust from scratch. This task becomes extremely challenging when it is simultaneously necessary to protect the privacy of the users involved. In this paper * , we first show how trust evaluation process of the user's system can be based on previous accesses and peer recommendations. A solution then relied on trust to control access is proposed that depends upon pre-defined access control security policy. Several tuning parameters and options are suggested so that end-users can customize to meet the security and privacy requirement of a ubiquitous system.

Research paper thumbnail of Realization and simulation of rocket multiple ignition system based on fuzzy control air-pasty

Aiming at the limited problem of multiple ignition time interval for pasty propellant rocket, pla... more Aiming at the limited problem of multiple ignition time interval for pasty propellant rocket, plasma ignition plan was proposed. Based on working process of plasma multiple ignitions, fuzzy control system was designed accordingly. On the base of electronic performance of plasma arc, the design of fuzzy controller was introduced in detail, and status recognition, control and detection of the whole ignition process was realized. Simulation of Matlab and semi-physical experimental simulation were performed. Results show the fuzzy controller has good control property. The purpose of design was attained.

Research paper thumbnail of A configuration for future giant telescope

Chinese Astronomy and Astrophysics, 2004

A configuration for the Future Giant Telescope is proposed. It is a 30 m telescope with segmented... more A configuration for the Future Giant Telescope is proposed. It is a 30 m telescope with segmented primary mirror and alt-azimuth mounting. The aspherical f/1.2 primary mirror is made up of 1095 partial annular submirrors. The optical system includes a Nasmyth system, a coud6 system and a wide field system. The Nasmyth system has a novel design with four mirrors and provides a ,~10 arcmin field of diffraction-limited images, a much larger field than can be obtained by the traditional Nasmyth system. Several diffractionlimited observations each over a small field, can be carried out simultaneously. By applying active optics to change the shape, tip, tilt and piston of the submirrors, thereby to effect a new aspherical surface of the primary, excellent quality images can be obtained for the coud4 system and the wide field system. The wide field system has a field of 25 arcmin, the focal surface is only slightly curved and the atmospheric dispersion could be corrected. The tolerances of the surface shape and position for the submirrors, and the telescope mounting and structure are also discussed. The innovations in this configuration should have a general significance for future giant telescopes.

Research paper thumbnail of Du lich sinh thai

Log In