5876317
Framework of performance evaluation for mobile process based on mobile ambient
Formal methodology for distributed and concurrent system, especially computation system with mobility, is increasingly important both in the theory and the practice. Based on the calculus of mobile ambient (MA), a widely studied formal mechanism for mobile computation, this paper focuses on the quantitative analysis of mobile computation system and provides a framework of performance evaluation for it. In details, this paper introduces an enhanced labelled transition system as the system model, and assigns rate to each label through so-called cost function. Based on it, the labelled transition system can be mapped to continuous time Markov chains and thus performance evaluation can be carried out by standard numerical techniques and tools. In some sense the main work of this paper can be regarded as integrating behavior and performance analysis in a compositional formal framework, which provides some basis of unified formal methodology for the development of mobile system.
17432425
Structure analysis for dynamic software architecture
The open and dynamic Internet environment greatly urges software entities that are distributed on different locations to coordinate with each other to accomplish a computing task. Software architecture is applied to abstract the software entities to be components and the coordination between them to be connectors and then a model is extracted as the architecture on which the design, analysis and verification are based. Currently, the notion of dynamic software architectures that can modify their architecture and enact modifications during the system execution has become one of the most active research areas. In this paper, we focus on the dynamic evolution of system structure other than coordination mechanisms (e.g. communication protocols). It is widely recognized that some restrictions should be imposed on the system evolution to ensure that the system structure may remain one style or transform within a scope. These conditions, to a large extent, make the system execute under control as expected.
1214419
On the Axiomatizability of Priority
This paper studies the equational theory of bisimulation equivalence over the process algebra BCCSP extended with the priority operator of Baeten, Bergstra and Klop. It is proven that, in the presence of an infinite set of actions, bisimulation equivalence has no finite, sound, ground-complete equational axiomatization over that language. This negative result applies even if the syntax is extended with an arbitrary collection of auxiliary operators, and motivates the study of axiomatizations using conditional equations. In the presence of an infinite set of actions, it is shown that, in general, bisimulation equivalence has no finite, sound, ground-complete axiomatization consisting of conditional equations over BCCSP. Sufficient conditions on the priority structure over actions are identified that lead to a finite, ground-complete axiomatization of bisimulation equivalence using conditional equations
5970126
On the Complete Axiomatization for Prefix Iteration modulo Observation Congruence
Prefix iteration is a variation on the original binary version of the Kleene star operation P*Q, obtained by restricting the first argument to be an atomic action. Aceto and Ingolfsdottir provided an axiom system for observation congruence over basic CCS with prefix iteration. However hitherto the only direct completeness proof given for such a system is very long and technical. In this paper, we provide a new proof for the completeness of the axiom system in [3], which is a considerable simplification comparing to the original proof. Thus the open problem to find a direct completeness proof is closed.
4863
On Finite Alphabets and Infinite Bases II: Completed and Ready Simulation
We prove that the equational theory of the process algebra BCCSP modulo completed simulation equivalence does not have a finite basis. Furhermore, we prove that with a finite alphabet of actions, the equational theory of BCCSP modulo ready simulation equivalence does not have a finite basis. In contrast, with an infinite alphabet, the latter equational theory does have a finite basis.
8665982
Structure analysis for dynamic software architecture based on spatial logic
The requirement for modifying system structure during system execution is specified by dynamic software architectures. The system architecture style should remain one style or transform within a scope so that some constraints need to be imposed on during the system execution. Our work expands such an idea along two directions in the setting of formalism. The first direction is to model the system by a graph-based calculus stressing the structure. The other direction lies in that we tailor spatial logic to be a suitable logic as the system specification for structure. The model and specification are basis for the model checking algorithm that is to verify whether the system evolution satisfies some structure constraints. We invite a master-slave architecture style as a running example from the beginning and throughout the paper to demonstrate our approach. Such work can be seen as the basis of the structure analysis for architectures.
23513255
A public verifiable copy protection technique for still images
It is well known that a digital signature scheme and digital timestamp are two well-defined security methods for copyright protection. However, these techniques are not suitable for directly dealing with digital images. For this reason, digital watermarking has received considerable attention for copyright protection. Unfortunately, there are still some challenges in the proposed watermarking schemes. Here, we will introduce cryptographic tools into watermarking, in such a way that both the advantages of cryptographic tools and digital watermarking are available. The publicly verifiable property and tolerant distortion property are therefore possible. Based on this idea, a lossless and robust copyright-protection scheme, distinct from conventional watermarking techniques, is proposed. Our scheme is strong enough to resist common image processing, geometric distortions and some intentional attacks. Some of the attacks are still challenges for the proposed watermarking methods. A series of experiments are conducted to prove the robustness property. The StirMark and unZign attacks are adopted as benchmark verification.
4650146
A New Coarse-to-Fine Framework for 3D Brain MR Image Registration
Registration, that is, the alignment of multiple images, has been one of the most challenging problems in the field of computer vision. It also serves as an important role in biomedical image analysis and its applications. Although various methods have been proposed for solving different kinds of registration problems in computer vision, the results are still far from ideal when it comes to real world biomedical image applications. For instance, in order to register 3D brain MR images, current state of the art registration methods use a multi-resolution coarse-to-fine algorithm, which typically involves starting with low resolution images and working progressively through to higher resolutions, with the aim to avoid the local maximum "traps". However, these methods do not always successfully avoid the local maximum. Consequently, various rather sophisticated optimization methods are developed to attack this problem. In this paper, we propose a novel viewpoint on the coarse-to-fine registration, in which coarse and fine images are distinguished by different scales of the objects instead of different resolutions of the images. Based on this new perspective, we develop a new image registration framework by combining the multi-resolution method with novel multi-scale algorithm, which could achieve higher accuracy and robustness on 3D brain MR images. We believe this work has great contribution to biomedical image analysis and related applications.
295636
Agent-Based Forwarding Strategies for Reducing Location Management Cost in Mobile Networks
An important issue in location management for dealing with user mobility in wireless networks is to reduce the cost associated with location updates and searches. The former operation occurs when a mobile user moves to a new location registration area and the network is being informed of the mobile user's current location; the latter operation occurs when there is a call for the mobile user and the network must deliver the call to the mobile user. In this paper, we propose and analyze a class of new agent-based forwarding schemes with the objective to reduce the location management cost in mobile wireless networks. We develop analytical models to compare the performance of the proposed schemes with existing location management schemes to demonstrate their feasibility and also to reveal conditions under which our proposed schemes are superior to existing ones. Our proposed schemes are particularly suitable for mobile networks with switches which can cover a large number of location registration areas.
17774823
Scalable Partitioning and Exploration of Chemical Spaces Using Geometric Hashing
Virtual screening (VS) has become a preferred tool to augment high-throughput screening(1) and determine new leads in the drug discovery process. The core of a VS informatics pipeline includes several data mining algorithms that work on huge databases of chemical compounds containing millions of molecular structures and their associated data. Thus, scaling traditional applications such as classification, partitioning, and outlier detection for huge chemical data sets without a significant loss in accuracy is very important. In this paper, we introduce a data mining framework built on top of a recently developed fast approximate nearest-neighbor-finding algorithm(2) called locality-sensitive hashing (LSH) that can be used to mine huge chemical spaces in a scalable fashion using very modest computational resources. The core LSH algorithm hashes chemical descriptors so that points close to each other in the descriptor space are also close to each other in the hashed space. Using this data structure, one can perform approximate nearest-neighbor searches very quickly, in sublinear time. We validate the accuracy and performance of our framework on three real data sets of sizes ranging from 4337 to 249 071 molecules. Results indicate that the identification of nearest neighbors using the LSH algorithm is at least 2 orders of magnitude faster than the traditional k-nearest-neighbor method and is over 94% accurate for most query parameters. Furthermore, when viewed as a data-partitioning procedure, the LSH algorithm lends itself to easy parallelization of nearest-neighbor classification or regression. We also apply our framework to detect outlying (diverse) compounds in a given chemical space; this algorithm is extremely rapid in determining whether a compound is located in a sparse region of chemical space or not, and it is quite accurate when compared to results obtained using principal-component-analysis-based heuristics.
44631758
Agent-based forwarding strategies for reducing location management cost in mobile networks
A major issue with location management in mobile wireless networks is the high cost associated with location updates and searches. A search occurs when a caller needs to connect to a mobile user whose location is unknown to the caller and the network must locate the callee. An update occurs when a mobile user moves into a new registration area and the network is informed of the location change. We propose and analyze a class of new agent-based forwarding strategies with the objective to reduce the location management cost in mobile wireless networks. We develop analytical Markov models to compare the performance of the proposed strategies with existing location management schemes to demonstrate their feasibility and also to reveal conditions under which the proposed schemes are superior to existing ones.