Vol. 32 · No. 3

Based on the ring signature technology, the multi-receiver ID-based anonymous signcryption (MIBAS) is proposed, and its goal is to protect the privacy of the sender or so-called signer. In an MIBAS scheme, every receiver can verify whether the sender is a member of a trusted group and thus ensure the reliability of the message source, but he could not get the real sender. However, MIBAS paid no attention to privacy of the receivers and has not taken the privacy of the receivers into account during its design. Our analyses show that there widely exist the receiver privacy exposure and decryption unfairness problems in the existing multi-receiver ID-based signcryption schemes. Motivated by these concerns, a new multi-receiver ID-based anonymous signcryption (nMIBAS) is proposed to protect the identity of the receivers. The nMIBAS scheme can not only solve the problem that the existing schemes cannot protect the privacy of receivers, but also meet the fairness of decryption to prevent the possible cheating behavior of the sender effectively. Analysis shows that this scheme is a secure and effective signcryption scheme.

Cloud computing has paved the way for advance of IT-based on demand services. This technology helps decrease capital expenditure and operation costs, solve scalability issue and many more user and provider constraints. However, development and deployment of distributed applications on cloud environment becomes a more and more complex task. Cloud users must spend a lot of time to prepare, install and configure their applications on clouds. In addition, after development and deployment, the applications almost cannot move from one cloud to another due to the lack of interoperability between them. To address these problems, in this paper we present a novel development and deployment framework for cloud distributed applications/services. Our approach is based on abstraction and object-oriented programming technique, allowing users to easily and rapidly develop and deploy their services into cloud environment. The approach also enables service migration and interoperability among the clouds.

Nowadays, nonlinear control is a very important task because machines are playing an ever increasing role in life. Lyapunov's 2 rm nd method is a popular tool by the use of which various controllers can be designed like adaptive neural networks, fuzzy controllers, and neuro-fuzzy solutions, or the sliding mode controllers and the well-known PID feedback controllers. Robust Fixed Point Transformation is a procedure which can be built for almost any type of controller in case an approximate model is used to estimate the controlled system's behavior. In this paper, a new approach to Robust Fixed Point Transformations (RFPT) is introduced by integrating a second controller in the system. Authors show that this additional, ``recalculated'' controller not just improves the original controller's results, but halves the tracking errors achieved by the previous RFPT methods.

This paper presents DSP blocks which were developed to be used as basic elements for realization of the DSP algorithms. For this purpose the description DSL (Domain Specific Language) language was used. The goal of this paper is to define and present a high level language that allows description and development of signal processing algorithms. With the usage of a domain specific language, one can create a compact and easy to understand definition of algorithms. In the paper the authors present the advantages granted by DSL for DSP applications. The created definitions are hardware independent and they can be executed and functionally verified. Efficient code can be generated for various targets without porting. The design of the presented DSL allows code generation for multi-core targets in case of computing-intensive algorithms, code generation for multiple streams and threads. To validate the results these blocks were made available for use to students as an easy method for the introduction of the DSP algorithms in sound and image processing. The main purpose was for the students to gain some basic insight into elementary techniques needed for design, implementation and merging of hardware and software components used in testing of the algorithms for digital signal processing in real time. Through the work with the students it was concluded that the developed DSP blocks presented very good assistance in educational process and therefore this paper was elaborated on that idea. Since real hardware systems were used in this case noise was introduced in the system which does not exist in simulation software and therefore this option produced much larger capabilities for development of the robust algorithms.

A simple and robust greedy algorithm has been proposed for efficient and quality decimation of polygonal models. The performance of a simplification algorithm depends on how the local geometric deviation caused by a local decimation operation is measured. As normal field of a surface plays key role in its visual appearance, exploiting the local normal field deviation in a novel way, a new measure of geometric fidelity has been introduced. This measure has the potential to identify and preserve the salient features of a surface model automatically. The resulting algorithm is simple to implement, produces approximations of better quality and is efficient in running time. Subjective and objective comparisons validate the assertion. It is suitable for applications where the focus is better speed-quality trade-off, and simplification is used as a processing step in other algorithms.

Despite the fact that using the services of outsourced data stream servers has been welcomed extremely, still the problem of obtaining assurance about the received results from these untrusted servers in unsecure environment is one of the basic challenges. In this paper, we present a probabilistic model for auditing received results from an outsourced data stream server through unsecure communication channels. In our architecture, the server is considered as a black box and the auditing process is fulfilled by cooperation between the data stream owner and users. Our method imposes an ignorable overhead on the user and needs no change in the structure of the server. The probabilistic modeling of the system proves algorithms convergence and the experimental evaluations show very acceptable results.

Considering predominant aspect-oriented software development (asymmetric AOSD), this paper discusses the application of aspect-oriented UML use case diagrams and formal language AspectZ to part of a classic AOSD case study, the Health-Watcher software system. In addition, this article proposes an extension of AspectZ to reach a new property for asymmetric AOSD which reacts after a schema successfully finishes, or not, showing messages for that situation, with an implicit join point; and a way for generalizing similar operations in a system using AspectZ. Thus, the main goal of this article is to show the application of and differences between asymmetric aspect-oriented formal and non-formal modeling, and to highlight potential advantages of aspect-oriented formal modeling over aspect-oriented non-formal modeling. First, this article describes the main concepts of the classic AOSD paradigm focusing on problems unsolved by previous forms of software development and resolved by AOSD. Second, by applying aspect-oriented UML use case diagrams, this paper highlights the use of dominion classes and extend-relationships. Considering the Health-Watcher case study and an asymmetric AOSD approach, this study found that using extend-relationships in UML use cases does not completely follow the basic principles of the prevailing AOSD approach in which a base element does not know about aspects, whereas an extending use case must explicitly know its extension points. Third, this article shows a formal modeling of the case study using AspectZ. Moreover, extensions of this aspect-oriented formal language are proposed and applied to the same case study to show their practical properties for modeling. These extensions allow showing success or error messages, and inserting or not a new item in a set of elements to take care of invalid situations.

Grammatical Evolution Guided by Reinforcement is an extension of Grammatical Evolution that tries to improve the evolutionary process adding break a learning process for all the individuals in the population. With this aim, each individual is given a chance to learn through a reinforcement learning mechanism during its lifetime. The learning process is completed with a Lamarckian mechanism in which an original genotype is replaced by the best learnt genotype for the individual. In a way, Grammatical Evolution Guided by Reinforcement shares an important feature with other hybrid algorithms, i.e. global search in the evolutionary process combined with local search in the learning process. In this paper the role of the Lamarck Hypothesis is reviewed and a solution inspired only in the Baldwin effect is included as well. Besides, different techniques about the trade-off between exploitation and exploration in the reinforcement learning step followed by Grammatical Evolution Guided by Reinforcement are studied. In order to evaluate the results, the system is applied on two different domains: a simple autonomous navigation problem in a simulated Kephera robot and a typical Boolean function problem.

Learners learn differently because they are different – and they grow more distinctive as they mature. Personalized learning occurs when e-learning systems make deliberate efforts to design educational experiences that fit the needs, goals, talents, and interests of their learners. Researchers had recently begun to investigate various techniques to help teachers improve e-learning systems. In this paper we present our design and implementation of an adaptive and intelligent web-based programming tutoring system – Protus, which applies recommendation and adaptive hypermedia techniques. This system aims at automatically guiding the learner's activities and recommend relevant links and actions to him/her during the learning process. Experiments on real data sets show the suitability of using both recommendation and hypermedia techniques in order to suggest online learning activities to learners based on their preferences, knowledge and the opinions of the users with similar characteristics.