43360105
Factorizations of regular graphs
Let G be a k-regular graph of order 2n such that k≥n. Hilton (J. Graph Theory, 9 (1985), 193–196) proved that G contains at least ⌊k3⌋ edge-disjoint 1-factors. Hilton's theorem is improved in this paper that G contains at least ⌊k2⌋ edge-disjoint 1-factors. The following result is also proved in this paper: Let G be a 2-connected, k-regular, non-bipartite graph of order at most 3k − 3 and x, y be a pair of distinct vertices. If Gβ {x, y} is connected, then G contains an (x, y)-Hamilton path.
20128924
Long path connectivity of regular graphs
Abstract Any pair of vertices in a 4-connected non-bipartite k -regular graph are joined by a Hamilton path or a path of length at least 3 k −6.
38249565
An extreme problem concerning k-arc-cyclic property for a class of tournaments
B. Alspach has proved that a regular tournament is arc-pancyclic. Zhu and Tian proved that if a tournament T = (V, A) with vertex set V, arc set A and order p satisfies that for any arc (vi, vj) of T, if d+(vj)+d-(vi)⩾p−2, then T is arc-pancyclic, where p⩾7. In this paper we study an extreme problem concerning the k-arc-cyclic property for a class of tournaments. 
 
We say that a tournament T=(V, A) satisfies the condition O(p, q) if d+(v)+d-(u)⩾p−q for any arc (u, v) of T, where q is a positive integer and |V|=p. Zhu, Tian, Chen and Zhang proved that if a tournament T satisfies the condition O(p, q) and p⩾3q+3, then T is arc-pancyclic. Let S(p, q) be the set{T=(V, A): T is a tournament with p vertices and T satisfies the condition O(p, q)}; let Ck(u, v) be the set {cycles of T with length k using the arc (u, v)}. The aim of this paper is that for a given integer q, we can find an integer m(q, k) such that if p⩾m(q, k), then for any T ϵ S(p, q), T is k-arc-cyclic; if p⩽m(q, k)−1, then there exists T ϵ S(p, q) such that T is not k-arc-cyclic. We have found that m(q, 4)=5q−7, and m(q, 5)=⌊p∗(q)⌋+1 or ⌈p∗(q)⌉+1, where p∗(q)=(1+312)q−(1+43·3 12).
27692910
Dominating cycles in regular 3-connected graphs
Abstract Let G be a 3-connected, k -regular graph on at most 4 k vertices. We show that, for k ⩾63, every longest cycle of G is a dominating cycle. We conjecture that G is in fact hamiltonian.
1667264
Path extendability of claw-free graphs
Let G be a connected, locally connected, claw-free graph of order n and x,y be two vertices of G. In this paper, we prove that if for any 2-cut S of G, S@?{x,y}=@A, then each (x,y)-path of length less than n-1 in G is extendable, that is, for any path P joining x and y of length h(
3757616
Hamilton cycles in 1-tough triangle-free graphs
A graph G is called triangle-free if G has no induced K3 as a subgraph. We set σ3=min{∑i=13d(vi)|{v1,v2,v3} is an independent set of vertices in G}. In this paper, we show that if G is a 1-tough and triangle-free graph of order n with n⩽σ3, then G is hamiltonian.
1253650
A reconfigurable, multi-gigahertz pulse shaping circuit based on distributed transversal filters
A distributed transversal filter (DTF) is a good candidate for ultrafast pulse shaping in wideband systems like UWB. This paper presents the circuit analysis of DTFs based on transmission line theory. We also show the detailed design procedure of DTFs. A 5-tap prototype DTF is designed and fabricated using microwave PCB substrate and pHEMT discrete transistors. Simulation and initial measurement results demonstrate its pulse shaping capability
6280246
A dynamic load balancing scheme for I/O-intensive applications in distributed systems
In this paper, a new I/O-aware load-balancing scheme is presented to improve overall performance of a distributed system with a general and practical workload including I/O activities. The proposed scheme dynamically detects I/O load imbalance on nodes of a distributed system and determines whether to migrate the I/O requests of some jobs from overloaded nodes to other less- or under-loaded nodes, depending on data migration cost and remote I/O access overhead. Besides balancing I/O load, the scheme judiciously takes into account both CPU and memory load sharing in distributed systems, thereby maintaining the same level of performance as the existing schemes when I/O load is low or well balanced. Results from a trace-driven simulation study show that, compared with the existing schemes that only consider CPU and memory, the proposed scheme reduces the mean slowdown by up to 54.5% (with an average of 39.9%). On the other hand, when compared to the existing approaches that only consider I/O, the proposed scheme reduces the mean slowdown by up to 57.2% (with an average of 31.6%). More importantly, the new scheme improves over a very recent algorithm found in the literature that considers all the three resources by up to 49.6% (with an average of up to 41.9%).
38631034
A Receiver-Centric Transport Protocol for Mobile Hosts with Heterogeneous Wireless Interfaces
Numerous transport protocols have been proposed in related work for use by mobile hosts over wireless environments. A common theme among the design of such protocols is that they specifically address the distinct characteristics of the last-hop wireless link, such as random wireless errors, round-trip time variations, blackouts, handoffs, etc. In this paper, we argue that due to the defining role played by the wireless link on a connection’s performance, locating the intelligence of a transport protocol at the mobile host that is adjacent to the wireless link can result in distinct performance advantages. To this end, we present a receiver-centric transport protocol called RCP (Reception Control Protocol) that is a TCP clone in its general behavior, but allows for better congestion control, loss recovery, and power management mechanisms compared to sender-centric approaches. More importantly, in the context of recent trends where mobile hosts are increasingly being equipped with multiple interfaces providing access to heterogeneous wireless networks, we show that a receiver-centric protocol such as RCP can enable a powerful and comprehensive transport layer solution for such multi-homed hosts. Specifically, we describe how RCP can be used to provide: (i) a scalable solution to support interface specific congestion control for a single active connection; (ii) seamless server migration capability during handoffs; and (iii) effective bandwidth aggregation when receiving data through multiple interfaces, either from one server, or from multiple replicated servers. We use both packet level simulations, and real Internet experiments to evaluate the proposed protocol.
2340130
Improved read performance in a cost-effective, fault-tolerant parallel virtual file system (CEFT-PVFS)
Due to the ever-widening performance gap between processors and disks, I/O operations tend to become the major performance bottleneck of data-intensive applications on modern clusters. If all the existing disks on the nodes of a cluster are connected together to establish high performance parallel storage systems, the cluster's overall performance can be boosted at no additional cost. CEFT-PVFS (a RAID 10 style parallel file system that extends the original PVFS), as one such system, divides the cluster nodes into two groups, stripes the data across one group in a round-robin fashion, and then duplicates the same data to the other group to provide storage service of high performance and high reliability. Previous research has shown that the system reliability is improved by a factor of more than 40 with mirroring while maintaining a comparable write performance. This paper presents another benefit of CEFT-PVFS in which the aggregate peak read performance can be improved by as much as 100% over that of the original PVFS by exploiting the increased parallelism. Additionally, when the data servers, which typically are also computational nodes in a cluster environment, are loaded in an unbalanced way by applications running in the cluster, the read performance of PVFS will be degraded significantly. On the contrary, in the CEFT-PVFS, a heavily loaded data server can be skipped and all the desired data is read from its mirroring node. Thus the performance will not be affected unless both the server node and its mirroring node are heavily loaded.
15780176
Understanding the design space of referencing in collaborative augmented reality environments
For collaborative environments to be successful, it is critical that participants have the ability to generate effective references. Given the heterogeneity of the objects and the myriad of possible scenarios for collaborative augmented reality environments, generating meaningful references within them can be difficult. Participants in co-located physical spaces benefit from non-verbal communication, such as eye gaze, pointing and body movement; however, when geographically separated, this form of communication must be synthesized using computer-mediated techniques. We have conducted an exploratory study using a collaborative building task of constructing both physical and virtual models to better understand inter-referential awareness -- or the ability for one participant to refer to a set of objects, and for that reference to be understood. Our contributions are not necessarily in presenting novel techniques, but in narrowing the design space for referencing in collaborative augmented reality. This study suggests collaborative reference preferences are heavily dependent on the context of the workspace.