We give a comprehensive theoretical treatment for calculating the viewshed of a given point, present an analytical solution to the viewshed problem and a new algorithm for finding the viewshed on a triangulated terrain. We implement our algorithm on a real terrain. Some algorithms make use of the horizon information of the terrain to calculate viewshed. The vertices of the horizon of the terrai...

scheduling has become an attractive area for artificial intelligence researchers. on other hand, in today's real-world manufacturing systems, the importance of an efficient maintenance schedule program cannot be ignored because it plays an important role in the success of manufacturing facilities. a maintenance program may be considered as the heath care of manufacturing machines and equip...

There is an urgent need for a reference conceptual framework regarding the understanding of business processes based on the Language-Action Perspective (LAP). Several frameworks have been proposed in the past years, but they appear to differ in several important aspects, and none of them is widely accepted yet. This paper intends to contribute to the establishment of such a framework. It does s...

The aim of this primarely theoretical paper is to discuss the use of e-government frameworks and benchmarking tools. It is frequently claimed that providing an effective egovernment assessment framework is a necessary condition for advancing e-government. However, there are major drawbacks in many of the existing e-government frameworks and surveys, as e.g. lack of a clearly defined purpose, an...

Covalent organic frameworks are a class of crystalline organic porous materials that can utilize π-π-stacking interactions as a driving force for the crystallization of polygonal sheets to form layered frameworks and ordered pores. However, typical examples are chemically unstable and lack intrasheet π-conjugation, thereby significantly limiting their applications. Here we report a chemically s...

Despite theoretical differences between item response theory (IRT) and classical test theory (CTT), there is a lack of empirical knowledge about how, and to what extent, the IRTand CTT-based item and person statistics behave differently. This study empirically examined the behaviors of the item and person statistics derived from these two measurement frameworks. The study focused on two issues:...

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BACKGROUND Tuberculosis is a major cause of morbidity and mortality globally. Recent scholarly attention to public health ethics provides an opportunity to analyze several ethical issues raised by the global tuberculosis pandemic. DISCUSSION Recently articulated frameworks for public health ethics emphasize the importance of effectiveness in the justification of public health action. This pap...

This paper considers the problem of planning collision-free motion of three disks in the plane. One of the three disks, the robot, can autonomously translate in the plane, the other two move only when in contact with the robot. This represents the abstract formulation of a manipulation planning problem. Despite the simplicity of the formulation, the decidability of the problem had remained unpr...

The electronic commerce for Small and Medium Enterprises on the part of Business-to-Business trade is experiencing difficulties due to the nature of the processes involved. SMEs fail to penetrate the B2B market due to lack of understanding, lack of finances and lack of IT experts that can create customized applications for standardized B2B ecommerce, such as ebXML. COTS software costs a lot, an...