12385194
Key research issues in grid workflow verification and validation
In the grid architecture, a grid workflow system is a type of high-level grid middleware which is supposed to support modelling, redesign and execution of large-scale sophisticated e-science and e-business processes in many complex scientific and business applications. To ensure the correctness of grid workflow specification and execution, grid workflow verification and validation must be conducted so that we can identify any violations and consequently take proper action to remove them in time. However, current research on the grid workflow verification and validation is just at the early stage and very few projects focus on them. Therefore, a systematic identification of key research issues in the grid workflow verification and validation field is no doubt helpful and should be presented so that we can be on the right track and reduce unnecessary work as far as possible. Hence, in this paper, we systematically analyse the grid workflow verification and validation and investigate their key research issues. Especially, we identify some important open research points which are not discussed by the current research and hence need further investigation. All these analyses form a big picture for the grid workflow verification and validation.
15506877
Flexible Temporal Consistency for Fixed-Time Constraint Verification in Grid Workflow Systems
To verify fixed-time constraints in grid workflow systems, the consistency and inconsistency conditions have been defined in the conventional work. However, in this paper, we argue that although the conventional consistency condition is reasonable, the conventional inconsistency condition is too rigorous and covers several different situations. These situations which are handled conventionally by the same exception handling should be handled differently for cost saving. Therefore, we divide the conventional inconsistency into weak consistency,weak inconsistency and strong inconsistency and treat the conventional consistency as strong consistency. Correspondingly, we discuss how to verify them. Especially, for the weak consistency, we present a method on how to adjust it to the strong consistency. For the weak inconsistency, we analyse why it can be handled by simpler and more economical exception handling. The final comparison and discussion further demonstrate that our research can achieve better cost effectiveness than the conventional work.
26682479
Web-Based Collaborative Tools for Geospatial Data Exploration
Federal government agencies have collected large and highly complex federal statistical summaries and geo-reference data. Methods and tools for identifying patterns and uncovering multivariate relationships in the complex datasets have drawn attention in multiple fields. The approach we present here extends from and integrates perspectives from multiple fields, including exploratory data analysis (EDA), geovisualization, information visualization, and data mining. Important components of our research are supported by a NSF Digital Government grant (#99883451). Other support comes from a National Cancer Institute (NCI) contract. Our DG research is now being extended to develop comprehensive multivariate analysis methods and tools, through a grant from NCI (CA95949).
35624108
Optimal Parallel Routing in Star Graphs
Star graphs have been recently proposed as attractive alternatives to the popular hypercube for interconnecting processors on a parallel computer. In this paper, we present an efficient algorithm that constructs an optimal parallel routing in star graphs. Our result improves previous results for the problem.
204766
Scalability, fidelity, and containment in the potemkin virtual honeyfarm
The rapid evolution of large-scale worms, viruses and bot-nets have made Internet malware a pressing concern. Such infections are at the root of modern scourges including DDoS extortion, on-line identity theft, SPAM, phishing, and piracy. However, the most widely used tools for gathering intelligence on new malware -- network honeypots -- have forced investigators to choose between monitoring activity at a large scale or capturing behavior with high fidelity. In this paper, we describe an approach to minimize this tension and improve honeypot scalability by up to six orders of magnitude while still closely emulating the execution behavior of individual Internet hosts. We have built a prototype honeyfarm system, called Potemkin, that exploits virtual machines, aggressive memory sharing, and late binding of resources to achieve this goal. While still an immature implementation, Potemkin has emulated over 64,000 Internet honeypots in live test runs, using only a handful of physical servers.
44387886
Fuzzy logic or Lukasiewicz logic: A clarification
Abstract We discuss some issues on fuzzy logic developed by Pavelka [Z. Math. Logic 25 (1979) 45–52, 119–134, 447–464] vs. the many-valued Lukasiewicz's logic. The focus is on the proper choice of fuzzy implication operations, a question which has been addressed many times in the fuzzy research literature. Pavelka had shown in 1979 that the only natural way of formalizing fuzzy logic for truth values in the unit interval [0, 1] is by using Lukasiewicz's implication operator a → b = min {1, 1 - a + b } or some isomorphic form of it. Many other papers around the same time had attempted to formulate alternative definitions for a → b by giving intuitive justifications. There continues to be some confusion, however, even today about the right notion of fuzzy logic. Much of this confusion lies in the use of improper “an” (“or”) and the “not” operations and a misunderstanding of some of the key differences between “proofs” or inferencing in fuzzy logic and those in Lukasiewicz's logic. We point out the need for defining the strong conjunction operator “⊗” in connection with fuzzy Modus-ponens rule and why we do not need the fuzzy Syllogism inference rule. We formulate two requirements of the fuzzy implication operator, which are satisfied by Lukasiewicz's a → b , but which fail for many of the alternative definitions for “→”.
208047947
New Directions in 3D User Interfaces
Three-dimensional user interfaces (3D UIs) support user tasks in many non-traditional interactive systems such as virtual environments and augmented reality. Although 3D UI researchers have been successful in identifying basic user tasks and interaction metaphors, evaluating the usability of 3D interaction techniques, and improving the usability of many applications, 3D UI research now stands at a crossroads. Very few fundamentally new techniques and metaphors for 3D interaction have been discovered in recent years, yet the usability of 3D UIs in many real-world applications is still not at a desirable level. What directions should 3D UI researchers next explore to improve this situation? In this paper, we make some observations about the history of 3D UIs and the current state-of-the-art. Using this evidence, in addition to our own experience, we argue that 3D UI researchers should approach this problem using some new research approaches, which cluster around the concepts of specificity, flavors, implementation, and emerging technologies. We illustrate and discuss some of these new directions using case studies of research projects undertaken in our group. These explorations indicate the promise of these directions for further increasing our understanding of 3D interaction and 3D UI design, and for ensuring the usability of 3D UIs in future applications.