16630001
Model-based Runtime Verification Framework for Self-optimizing Systems
This paper describes a novel on-line model checking approach offered as service of a real-time operating system (RTOS). The verification system is intended especially for self-optimizing component-based real-time systems where self-optimization is performed by dynamically exchanging components. The verification is performed at the level of (RT-UML) models. The properties to be checked are expressed by RT-OCL terms where the underlying temporal logic is restricted to either time-annotated ACTL or LTL formulae. The on-line model checking runs interleaved with the execution of the component to be checked in a pipelined manner. The technique applied is based on on-the-fly model checking. More specifically for ACTL formulae this means on-the-fly solution of the NHORNSAT problem while in the case of LTL the emptiness checking method is applied.
30853891
Comprehensive Verification Framework for Dependability of Self-optimizing Systems
By integrating formal specification and formal verification into the design phase of a system development process, the correctness of the system can be ensured to a great extent. However, it is not sufficient for a self-optimizing system that needs to exchange its components safely and consistently over time. Therefore, this paper presents a comprehensive verification framework to guarantee the dependability of such a self-optimizing system at the design phase (off-line verification) as well as at the runtime phase (on-line verification). The proposed verification framework adopts AsmL as intermediate representation for the system specification and on-the-fly model checking technique for alleviating the state space explosion problem. The off and the on -line verifications are performed at (RT-UML) model level. The properties to be checked are expressed by RT-OCL where the underlying temporal logic is restricted to time-annotated ACTL/LTL formulae. In particular, the on-line verification is achieved by running the on-the-fly model checking interleaved with the execution of the checked system in a pipelined manner.
36457558
Verification Framework for UML-Based Design of Embedded Systems
System level design incorporating system modeling and formal specification in combination with formal verification can substantially contribute to the correctness and quality of the embedded systems and consequently help reduce the development costs. Ensuring the correctness of the designed system is, of course, a crucial design criterion especially when complex distributed (realtime) embedded systems are considered. Therefore, this paper aims at presenting a verification framework designated for formal verification and validation of UML-based design of embedded systems. It first introduces an approach of using the AsmL language for acquiring formal models of the UML semantics and consequently presents an on-the-fly model checking technique designed to run the formal verification directly over those semantic models.
15935019
Statistical interval-valued fuzzy systems via linear regression
In recent years, the type-2 fuzzy sets theory has been used to model and minimize the effects of uncertainties in rule-base fuzzy logic system. In order to make the type-2 fuzzy logic system reasonable and reliable, a new simple statistical linear method to decide interval-valued fuzzy membership functions and a new probability type reduce reasoning method for the interval-valued fuzzy logic system are proposed in this paper. An example of statistical interval-valued FLS is performed and results show that the developed method is more accurate to design a fuzzy logic system than type-1 method and computation is efficient.
38902380
Construction Algorithm of Principal Curves in the Sense of Limit
Principal curves have been defined as self-consistent, smooth, one-dimensional curves which pass through the middle of a multidimensional data set. They are nonlinear generalization of the first Principal Component. In this paper, we take a new approach by defining principal curves as continuous curves based on the local tangent space in the sense of limit. It is proved that this new principal curves not only satisfy the self-consistent property, but also are the unique existence for any given open covering. Based on the new definition, a new practical algorithm for constructing principal curves is given. And the convergence properties of this algorithm are analyzed. The new construction algorithm of principal curves is illustrated on some simulated data sets.
11721850
Estimating LOC for information systems from their conceptual data models
Effort and cost estimation is crucial in software management. Estimation of software size plays a key role in the estimation. Line of Code (LOC) is still a commonly used software size measure. Despite the fact that software sizing is well recognized as an important problem for more than two decades, there is still much problem in existing methods. Conceptual data model is widely used in the requirements analysis for information systems. It is also not difficult to construct conceptual data models in the early stage of developing information systems. Much characteristic of an information system is actually reflected from its conceptual data model. We explore into the use of conceptual data model for estimating LOC. This paper proposes a novel method for estimating LOC for an information system from its conceptual data model through the use of multiple linear regression model. We have validated the method through collecting samples from both the industry and open-source systems.
8299246
HyLog: A High Performance Approach to Managing Disk Layout
Our objective is to improve disk I/O performance in multi-disk systems supporting multiple concurrent users, such as file servers, database servers, and email servers. In such systems, many disk reads are absorbed by large in-memory buffers, and so disk writes comprise a large portion of the disk I/O traffic. LFS (Log-structured File System) has the potential to achieve superior write performance by accumulating small writes into large blocks and writing them to new places, rather than overwriting on top of their old copies (called Overwrite). Although it is commonly believed that the high segment cleaning overhead of LFS makes it a poor choice for workloads with random updates, in this paper we find that because of the fast improvement of disk technologies, LFS significantly outperforms Overwrite in a wide range of system configurations and workloads (including the random update workload) under modern and future disks. 
 
LFS performs worse than Overwrite, however, when the disk space utilization is very high due to the high cleaning cost. In this paper, we propose a new approach, the Hybrid Log-structured (Hy-Log) disk layout, to overcome this problem. Hy-Log uses a log-structured approach for hot pages to achieve high write performance, and Overwrite for cold pages to reduce the cleaning cost. We compare the performance of HyLog to that of Overwrite, LFS and WOLF (the latest improvement on LFS) under various system configurations and workloads. Our results show that, in most cases, Hylog performs comparably to the best of the other three approaches.
184418
Self-adaptive clock synchronization for computational grid
This paper presents an innovative method to synchronize physical clocks for a computational grid, in particular for a computational grid linked through the asynchronous Intranet or Internet environments. The method discussed is an asynchronous self-adaptive clock synchronization mechanism. Two strategies for clock synchronisationare introduced. (1), Use continuous time intervals to calculate the precision of clocks, which can reduce the effect of network delay efficiently. (2) Every node synchronizes its clock, with its leader actively. In addition, a node self-adaptive model is presented, and the relationship between the clock precision and synchronization time is induced, hence a node can predict when it should begin the synchronization process. Detailed simulation and extension of this issue are provided at the end of the paper. The presented model is both practical and feasible.