16675541
The GAPLA: a globally asynchronous locally synchronous FPGA architecture
This paper proposes GAPLA: a globally asynchronous locally synchronous programmable logic array architecture. The whole FPGA area is divided into locally synchronous blocks wrapped with asynchronous I/O interfaces. Data communications between synchronous blocks are controlled by 2-phase handshaking signals. The size and shape of each locally synchronous block are programmable so that different modules in a design can be effectively implemented. Each block could run at higher speed because only the fast local interconnections are used. Experimental results show an up to 28% performance improvement compared to the conventional FPGAs with small area overhead (around 2%).
14531853
A novel asynchronous FPGA architecture design and its performance evaluation
This paper proposes GAPLA: a globally asynchronous locally synchronous programmable logic array architecture. The whole FPGA area is divided into locally synchronous blocks wrapped with asynchronous I/O interfaces. Data communications between synchronous blocks are controlled by 2-phase handshaking signals under bundled-data delay assumption. The size and shape of each locally synchronous block are programmable so that different modules in a design can be effectively implemented. By dividing the FPGA area into smaller blocks, the delays of long interconnect wires, which could easily dominate other delays in conventional FPGAs, only come into picture when there are communications between blocks. Therefore, each block could run at higher speed. The area overhead of adopting the GALS style in GAPLA architecture is estimated to be very small (about 7%). Experimental results show an up to 55% performance improvement compared to the conventional FPGAs.
26178565
A Design Methodology for Self-Timed Event Logic Pipelines
42148814
Using GALS architecture to reduce the impact of long wire delay on FPGA performance
2524138
Code synthesis based on object-oriented design models and formal specifications
Presents an approach to synthesizing functional and robust code from object-oriented design models and Z data and operation specifications. The approach used is based on an integrated notation of the Unified Modeling Language (UML) and a slightly extended Z notation to include object-oriented concepts and structures. Our approach generates fully functional code which can be compiled and executed without modifications. The information from object-oriented analysis and design models along with the formal specifications are combined, analyzed and translated into an intermediate representation from which code can be generated. A research prototype has been developed to demonstrate the feasibility and the effectiveness of our approach.
1493304
On random points in the unit disk
Let n be a positive integer and λ > 0 a real number. Let Vn be a set of n points in the unit disk selected uniformly and independently at random. Define G(λ, n) to be the graph with vertex set Vn, in which two vertices are adjacent if and only if their Euclidean distance is at most λ. We call this graph a unit disk random graph. Let λ = c √ lnn/n and let X be the number of isolated points in G(λ, n). We prove that almost always X ∼ n1−c2 when 0 ≤ c < 1. It is known that if λ = √ (ln n + φ(n))/n where φ(n) → ∞, then G(λ, n) is connected. By extending a method of Penrose, we show that under the same condition on λ, there exists a constant K such that the diameter of G(λ, n) is bounded above by K · 2/λ. Furthermore, with a new geometric construction, we show that when λ = c √ lnn/n and c > 2.26164 · · · , the diameter of G(λ, n) is bounded by (4 + o(1))/λ; and we modify this construction to yield a function c(δ) > 0 such that the diameter is at most 2(1 + δ + o(1))/λ when c > c(δ). ∗This is a preprint of an article accepted for publication in Random Structures and Algorithms c ©2005. †Partially supported by NSF grant DMS-9977354. ‡Partially supported by NSF grant DMS-0245526, DMS-0308827 and a Sloan Fellowship. The author is also affiliated with Dalian University of Technology.
19271257
Extremal Cayley Digraphs of Finite Cyclic Groups
Let $\cay(m,A)$ denote the Cayley digraph on ${\bf Z}_m$ generated by $A$, where ${\bf Z}_m$ is the cyclic group of residues modulo $m$. Let $r(m,A)$ denote the average distance of $\cay(m,A)$. For any $r\ge1$ and $k\ge1$ define $m^*(r,k)$ as the largest positive integer $m$ such that the average distance of the Cayley digraph $\hbox{Cay}(m,A)$ is at most $r$ for some set $A$ with $k$ elements. In this paper, an asymptotic formula for $m^*(r,2)$ is proved and a lower bound for $m^*(r,k)$ is also obtained for $k\ge3$. Applications to the construction of optimal distributed loop networks is discussed in this paper. A lower bound of the average order of subsets for asymptotic bases in number theory is proved using the main theorem of this paper.
6166247
Virtual backbone construction in multihop ad hoc wireless networks
Summary Recent research points out that the flooding mechanism for topology update or route request in existing ad hoc routing protocols greatly degrades the network capacity. If we restrict the broadcast of control packets within a small subset of hosts in the network, the protocol overhead can be substantially reduced. This motivates our research of constructing a virtual backbone by computing a connected dominating set (CDS) in unit-disk graphs. In this paper, we propose two distributed algorithms to approximate a minimum CDS. These algorithms take linear time. Their performance is verified by a complete theoretical analysis. Copyright # 2006 John Wiley & Sons, Ltd.
18149163
SMOQE: a system for providing secure access to XML
XML views have been widely used to enforce access control, support data integration, and speed up query answering. In many applications, e.g., XML security enforcement, it is prohibitively expensive to materialize and maintain a large number of views. Therefore, views are necessarily virtual. An immediate question then is how to answer queries on XML virtual views. A common approach is to rewrite a query on the view to an equivalent one on the underlying document, and evaluate the rewritten query. This is the approach used in the Secure MOdular Query Engine (SMOQE). The demo presents SMOQE, the first system to provide efficient support for answering queries over virtual and possibly recursively defined XML views. We demonstrate a set of novel techniques for the specification of views, the rewriting, evaluation and optimization of XML queries. Moreover, we provide insights into the internals of the engine by a set of visual tools.