Managing transactions is a key issue in Service Oriented Computing where particular relevance is given to the so called Long Running Transactions (LRT). Here, we show how to apply a formal approach to the specification and refactoring of LRT. Specifically, we consider a methodology arising on process calculi and show how it can be applied to a case study.

In the statistics literature, a number of procedures have been proposed for testing equality of several groups’ covariance matrices when data are complete, but this problem has not been considered for incomplete data in a general setting. This paper proposes statistical tests for equality of covariance matrices when data are missing. AWald test (denoted by T1), a likelihood ratio test (LRT) (de...

Large number of taxicabs in major metropolitan cities are now equipped with a GPS device. Since taxis are on the road nearly twenty four hours a day (with drivers changing shifts), they can now act as reliable sensors to monitor the behavior of traffic. In this paper we use GPS data from taxis to monitor the emergence of unexpected behavior in the Beijing metropolitan area. We adapt likelihood ...

Light Rail Transit (LRT) is a kind of rail vehicle form which includes from modern tramcars to speed transport. These vehicles go on special road, underground, floor or specific altitude. Today the number of active serving LRT systems in 50 countries is more than 400. Moreover, a forceful increase has been expected for next years. It is clear that this growing up has certain reasons. In this st...

A performance analysis of likelihood ratio test (LRT)-based and generalized likelihood ratio test (GLRT)based array receivers for the detection of a known real-valued signal corrupted by a potentially noncircular interference is considered in this paper. The distribution of the decision statistics associated with the LRT and GLRT is studied. This allows us to give exact closed-form expressions ...

The likelihood ratio test (LRT) method is a commonly used method of hypothesis test construction. The intersection-union test (JUT) method is a less commonly used method. We will explore some relationships between these two methods. We show that, under some conditions, both methods yield the same test. But, we also describe conditions under which the size-a JUT is uniformly more powerful than t...

Long-running transactions consist of tasks which may be executed sequentially and in parallel, may contain sub-tasks, and may require to be completed before a deadline. These transactions are not atomic and, in case of executions which cannot be completed, a compensation mechanism must be provided. In this paper we develop a model of Hierarchical Timed Automata suitable to describe the aspects ...

Relations among phenomena at different linguistic levels are at the essence of language properties but today we focus mostly on one specific linguistic layer at a time, without (having the possibility of) paying attention to the relations among the different layers. At the same time our efforts are too much scattered without much possibility of exploiting other people’s achievements. To address...

For i = 1, ... ,p, let Xi!, ... ,Xini denote independent random samples from normal populations. The ith population has unknown mean Jli and unknown variance a;. We consider the sign testing problem of testing Ho : Jli :::; ai, for some i = 1, ... ,p, versus HI : Jli > ai, for all i = 1, ... ,p, where al,." ,ap are fixed constants. Here, HI might represent p different standards that a product m...

This paper proposes a novel methodology to detect data hidden in the least significant bits of a natural image. The goal is twofold: first, the methodology aims at proposing a test specifically designed for natural images, to this end an original model of images is presented, and, second, the statistical properties of the designed test, probability of false alarm and power function, should be p...