Xin QI - Academia.edu (original) (raw)

Papers by Xin QI

Research paper thumbnail of A Virtual Deadline Scheduler for Window-Constrained Service Guarantees

This paper presents a new approach to windowconstrained scheduling, suitable for multimedia and w... more This paper presents a new approach to windowconstrained scheduling, suitable for multimedia and weakly-hard real-time systems. We originally developed an algorithm, called Dynamic Window-Constrained Scheduling (DWCS), that attempts to guarantee no more than x out of y deadlines are missed for real-time jobs such as periodic CPU tasks, or delay-constrained packet streams. While DWCS is capable of generating a feasible windowconstrained schedule that utilizes 100% of resources, it requires all jobs to have the same request periods (or intervals between successive service requests). We describe a new algorithm called Virtual Deadline Scheduling (VDS), that provides window-constrained service guarantees to jobs with potentially different request periods, while still maximizing resource utilization.

Research paper thumbnail of Structured optimal and robust control with multiple criteria: a convex solution

IEEE Transactions on Automatic Control, 2004

In this paper, the design of controllers that incorporate structural and multiobjective performan... more In this paper, the design of controllers that incorporate structural and multiobjective performance requirements is considered. The control structures under study cover nested, chained, hierarchical, delayed interaction and communications, and symmetric systems. Such structures are strongly related to several modern-day and future applications including integrated flight propulsion systems, platoons of vehicles, micro-electro-mechanical systems, networked control, control of networks, production lines and chemical processes. It is shown that the system classes presented have the common feature that all stabilizing controllers can be characterized by convex constraints on the Youla-Kucera parameter. Using this feature, a solution to a general optimal performance problem that incorporates time domain and frequency domain constraints is obtained. A synthesis procedure is provided which at every step yields a feasible controller together with a measure of its performance with respect to the optimal. Convergence to the optimal performance is established. An example of a multinode network congestion control problem is provided that illustrates the effectiveness of the developed methodology.

Research paper thumbnail of Optimal controller synthesis with multiple objectives

We present a methodology to address the general multiobjective (GMO) control problem involving th... more We present a methodology to address the general multiobjective (GMO) control problem involving the L1 norm, U2 norm, U, norm and time-domain constraint (TDC). We show that the problem resulted from imposing a regularizing condition always admits an optimal solution, and suboptimal solutions with performance arbitrarily close to the optimal cost can be obtained by constructing two sequences of finite dimensional convex optimization problems whose objective values converge to the optimum from below and above.

Research paper thumbnail of Secure web applications via automatic partitioning

Operating Systems Review, 2007

Swift is a new, principled approach to building web applications that are secure by construction.... more Swift is a new, principled approach to building web applications that are secure by construction. In modern web applications, some application functionality is usually implemented as client-side code written in JavaScript. Moving code and data to the client can create security vulnerabilities, but currently there are no good methods for deciding when it is secure to do so.

Research paper thumbnail of J&: nested intersection for scalable software composition

This paper introduces a programming language that makes it convenient to compose large software s... more This paper introduces a programming language that makes it convenient to compose large software systems, combining their features in a modular way. J& supports nested intersection, building on earlier work on nested inheritance in the language Jx. Nested inheritance permits modular, type-safe extension of a package (including nested packages and classes), while preserving existing type relationships. Nested intersection enables composition and extension of two or more packages, combining their types and behavior while resolving conflicts with a relatively small amount of code.

Research paper thumbnail of Secure web application via automatic partitioning

Swift is a new, principled approach to building web applications that are secure by construction.... more Swift is a new, principled approach to building web applications that are secure by construction. In modern web applications, some application functionality is usually implemented as client-side code written in JavaScript. Moving code and data to the client can create security vulnerabilities, but currently there are no good methods for deciding when it is secure to do so.

Research paper thumbnail of New BODIPY Derivatives as OFF−ON Fluorescent Chemosensor and Fluorescent Chemodosimeter for Cu 2+ : Cooperative Selectivity Enhancement toward Cu 2

Journal of Organic Chemistry, 2006

New 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives (1 and 2) were synthesized as... more New 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives (1 and 2) were synthesized as an "off-on" fluorescent chemosensor and fluorescent chemodosimeter for Cu2+ and Pb2+. Compound 1 displayed selective and large chelation enhanced fluorescence effects with Pb2+ and Cu2+ among the metal ions examined. On the other hand, compound 2, a fluorescent chemodosimeter, effectively recognized Cu2+ via a selective hydrolysis of the acetyl group.

Research paper thumbnail of Paper

Research paper thumbnail of A Virtual Deadline Scheduler for Window-Constrained Service Guarantees

This paper presents a new approach to windowconstrained scheduling, suitable for multimedia and w... more This paper presents a new approach to windowconstrained scheduling, suitable for multimedia and weakly-hard real-time systems. We originally developed an algorithm, called Dynamic Window-Constrained Scheduling (DWCS), that attempts to guarantee no more than x out of y deadlines are missed for real-time jobs such as periodic CPU tasks, or delay-constrained packet streams. While DWCS is capable of generating a feasible windowconstrained schedule that utilizes 100% of resources, it requires all jobs to have the same request periods (or intervals between successive service requests). We describe a new algorithm called Virtual Deadline Scheduling (VDS), that provides window-constrained service guarantees to jobs with potentially different request periods, while still maximizing resource utilization.

Research paper thumbnail of Structured optimal and robust control with multiple criteria: a convex solution

IEEE Transactions on Automatic Control, 2004

In this paper, the design of controllers that incorporate structural and multiobjective performan... more In this paper, the design of controllers that incorporate structural and multiobjective performance requirements is considered. The control structures under study cover nested, chained, hierarchical, delayed interaction and communications, and symmetric systems. Such structures are strongly related to several modern-day and future applications including integrated flight propulsion systems, platoons of vehicles, micro-electro-mechanical systems, networked control, control of networks, production lines and chemical processes. It is shown that the system classes presented have the common feature that all stabilizing controllers can be characterized by convex constraints on the Youla-Kucera parameter. Using this feature, a solution to a general optimal performance problem that incorporates time domain and frequency domain constraints is obtained. A synthesis procedure is provided which at every step yields a feasible controller together with a measure of its performance with respect to the optimal. Convergence to the optimal performance is established. An example of a multinode network congestion control problem is provided that illustrates the effectiveness of the developed methodology.

Research paper thumbnail of Optimal controller synthesis with multiple objectives

We present a methodology to address the general multiobjective (GMO) control problem involving th... more We present a methodology to address the general multiobjective (GMO) control problem involving the L1 norm, U2 norm, U, norm and time-domain constraint (TDC). We show that the problem resulted from imposing a regularizing condition always admits an optimal solution, and suboptimal solutions with performance arbitrarily close to the optimal cost can be obtained by constructing two sequences of finite dimensional convex optimization problems whose objective values converge to the optimum from below and above.

Research paper thumbnail of Secure web applications via automatic partitioning

Operating Systems Review, 2007

Swift is a new, principled approach to building web applications that are secure by construction.... more Swift is a new, principled approach to building web applications that are secure by construction. In modern web applications, some application functionality is usually implemented as client-side code written in JavaScript. Moving code and data to the client can create security vulnerabilities, but currently there are no good methods for deciding when it is secure to do so.

Research paper thumbnail of J&: nested intersection for scalable software composition

This paper introduces a programming language that makes it convenient to compose large software s... more This paper introduces a programming language that makes it convenient to compose large software systems, combining their features in a modular way. J& supports nested intersection, building on earlier work on nested inheritance in the language Jx. Nested inheritance permits modular, type-safe extension of a package (including nested packages and classes), while preserving existing type relationships. Nested intersection enables composition and extension of two or more packages, combining their types and behavior while resolving conflicts with a relatively small amount of code.

Research paper thumbnail of Secure web application via automatic partitioning

Swift is a new, principled approach to building web applications that are secure by construction.... more Swift is a new, principled approach to building web applications that are secure by construction. In modern web applications, some application functionality is usually implemented as client-side code written in JavaScript. Moving code and data to the client can create security vulnerabilities, but currently there are no good methods for deciding when it is secure to do so.

Research paper thumbnail of New BODIPY Derivatives as OFF−ON Fluorescent Chemosensor and Fluorescent Chemodosimeter for Cu 2+ : Cooperative Selectivity Enhancement toward Cu 2

Journal of Organic Chemistry, 2006

New 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives (1 and 2) were synthesized as... more New 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives (1 and 2) were synthesized as an "off-on" fluorescent chemosensor and fluorescent chemodosimeter for Cu2+ and Pb2+. Compound 1 displayed selective and large chelation enhanced fluorescence effects with Pb2+ and Cu2+ among the metal ions examined. On the other hand, compound 2, a fluorescent chemodosimeter, effectively recognized Cu2+ via a selective hydrolysis of the acetyl group.

Research paper thumbnail of Paper