In this paper we study combinatorial segment visibility, and show how to compute and maintain it as the observer moves in the plane. There are n non-overlapping convex objects in the plane, and we have a segment observer among them. We first consider static case of the problem, in which the observer and objects are static, and then we study dynamic case of the problem, in which the observer can move among obstacles.

Reversible Cellular Automata is applicable in cryptographic functions. A reversible CA can be obtained by employing reversible rules. In this paper, we propose 65280 two-dimensional reversible CA rules by compounding one-dimensional reversible rules. We produce these rules by alternately applying onedimensional CA rule f1 to the rows and applying another rule f2 to the columns of the configuration matrix of twodimensional CA. In addition to describing these rules, we consider the required cryptographic properties such as completeness, strict avalanche criteria, non-linearity, and differential-profile flatness for our proposed approach. According to the obtained results, 9463 rules are specified as appropriate rules for the purpose of applying in cryptographic functions. Only 510 rules do not satisfy any of the mentioned cryptographic properties and the other remain rules satisfy some of the properties.

The dynamic nature of service-oriented architecture (SOA), leads to a need for special attention about the turbulence of the quality attributes (or non-functional requirements) of software during the dynamic changes. If there exists a method for monitoring the whole quality of a service-oriented software, the service selector component of the architecture, which has the responsibility of choosing the best candidate service at runtime, can be aware of the quality state of the whole software at any moment of decision. In this paper, we have focused on the overall quality of an architecture which consists of multiple independent services and present a new method for tracing quality attributes in service oriented architecture based on Graph Transformation System (GTS) as a formal approach.

The existing workflow modeling languages have some limitations and drawbacks. The aim is to introduce a new workflow modeling language based on stochastic activity networks (SANs). SANs are a powerful extension of Petri nets, which have been used in a wide range of applications. SAN-based workflow modeling language (SWML) has some high-level modeling primitives for easily modeling workflow patterns. For analysis of the modeled workflow systems with SWML, we have introduced the transformation techniques from SWML models into ordinary SANs. The transformed models can be analyzed using the existing tools for SANs, such as the Möbius modeling tool. In this paper, we present definitions of SWML modeling language and its primitives and an example of SWML models.

With ever increasing complexity of software systems, it is now more evident than ever that a fundamental change in software engineering practices is required. In this paper we discuss the nature of change and its implications. The notion of passive autonomy is introduced as a reference to the relative autonomy of business entities, and we claim that realizing the passive autonomy in information systems would results in systems far more adaptable and aligned with business’ needs. In order to realize this autonomy, theuse of autonomous agents as representing real world autonomous entities is suggested. After pointing out the shortcomings of current agent based architectures, a new architecture is proposed, based on indirect, multilateral negotiation. The suitability of this architecture is demonstrated in a simple case of beer game and it is shown that the bullwhip effect is remedied to some extent using this new architectural approach.

Uncertainty reasoning has been identified as an important and challenging issue in the database research. Many logic frameworks have been proposed to represent and reason about uncertainty in deductive databases. On the basis of the way in which uncertainties are associated with the facts and rules in programs, the approaches of these frameworks have been classified into “annotation based (AB)” and “implication based (IB).” When extending both frameworks with certainty constraints, they become equivalent in terms of expressive power. In this paper, we propose a uniform environment to evaluate and experiment with logic programs in AB and IB frameworks at the same time. We also extend the existing query processing to handle certainty constraints and we carry out experiments to evaluate its performance. Our experiments and results indicate that the proposed techniques yield tools that are capable to reason with uncertainty.

با افز ايش قيمت ابرکامپ يوترها ا ز طرف ي و ني از به مناب ع محاسباتي با حجم وسيع از طرف ديگر، محقق ين کام پيوتر را بر آن داشته است تا به سراغ استفاده از شبکهاي از منابع محاسبا تي به نا م گريد Grid) روي آورند. گونهاي از گريد به نام گريد محاسباتي Computing Grid مجموعهاي از منابع توزيع شده را براي حل مس ايل با ميزان محاسبات بالا در علوم، مهندس ي و تجارت فراهم آورده اس ت . براي استفاده بهينه از قابليتهاي اين سيستم توزيع شده، الگوريتمه اي زمانبندي کارامدي موردنياز است . در اي ن مقاله الگو ر يتم زمانبن دي جديدي به کمک برنامهسازي ژنتيک و بر مبن اي دو الگور يتم پاي هاي Min-Min و Max-Min طراحي شده است که س ع ي در استفاده از مزاياي اين دو، رفع معايب آنه ا و کوتاه کردن مدت زمانبن د ي نموده است. با مقايسه کارا يي الگو ريتم جدي د با دو الگو ر يتم Min-Min و Max-Min نتايج قابل قبولي بدست آمد.

اين مقاله مسئله جداسازي كور سيستمهاي طيف گسترده پرش فركانسي (FHSS) را با استفاده از يك المان آرايهاي بدون دانستن الگوي پرش و يا جهت سيگنال ورودي (DOA) براي كاربردهاي زمانحقيقي مورد بررسي قرار ميدهد. در اين مقاله الگوريتم مورد استفاده، الگوريتم تخمين و قطري سازي توام ماتريس كاميولنت (JADE) ميباشد. مزيت اين الگوريتم، سرعت بالاي آن ميباشد كه باعث شده است براي كاربردهاي زمان-حقيقي مناسب باشد. اما مشكل الگوريتم JADE رعايت نكردن ترتيب منابع يا جايگشت آنها به هنگام جداسازي است. براي حل مشكل جايگشت در اين مقاله، از ماتريس همبستگي استفاده ميكنيم.