Development projects often depend on two or more process models, being not seamlessly integrated. It is therefore useful to have a consistent project-specific process model (PSPM) instead of letting the project members decide individually when inconsistencies occur. For repeatable processes and their direct enactment with workflow engines, the explicit construction of such a PSPM can be efficient, as one and the same type model results in many process instances. However, for the overarching and totally unique macro-process, there already exists a PSPM being updated more or less frequently: the project plan. Considering its central position within plan-based enactment it is well-suited to be used as a central point for the handling of unavoidable inconsistencies of all kinds. Unlike the situation for direct enactment, an adequate theory for plan-based enactment is not yet available and formal prescriptive approaches as used, e.g., for process automation can barely be applied. In this paper, we propose a descriptive mathematical model for project planning and controlling. It is based on functional decomposition and data flow and allows for repository-based consistency checks regarding goals, plans, and project status.

In this paper, we introduce an opportunistic networking protocol, denoted as NOPPoS, that assigns station and access point roles to mobile devices based on the number of mobile devices and access points in the proximity. As main novel feature, NOPPoS is highly responsive to node mobility due to periodic, low-energy scans of its environment. In fact, NOPPoS can determine the exact number of neighbors at any instant of time. Therefore, NOPPoS can assign roles to mobile devices in a more efficient way than previous approaches could do. We compare NOPPoS to WLAN-Opp that approximates the number of neighbors based on the stations in the previous access point. In a comparative performance study using real world mobility trace data, we show that NOPPoS substantially improves the distributed scheduling for activating a Wi-Fi access point on a mobile device. In particular, NOPPoS significantly increases the contact utilization ratio and avoids to open empty access points and therefore nodes spend less time in AP state. Moreover, it creates larger groups than WLAN-Opp and substantially reduces the energy consumption.

The management of a software development project is a demanding task. To plan and control the actions of the project participants, the existence of a suitable project plan is of critical importance. However, elaborating and maintaining such a project plan based on the employed process model typically requires a lot of manual effort, comprising many tedious and error-prone activities. This paper shows how plan-based enactment of processes can improve this situation, providing a basis for adequate method and tool support. The paper presents our approach for an integrated formal model covering process models, project plans and real life project actions. The model is simple, has a well-defined semantics and supports initial planning as well as plan refinement, re-planning and controlling. Furthermore, the paper sketches how the model can be put to practice and integrated into existing tools.

In this paper, we present a measurement study of the multi-hop behavior of the new IEEE 802.11n standard in an indoor mesh testbed. As main contribution, we quantitatively describe characteristics of IEEE 802.11n on multi-hop paths like throughput, aggregate size and utilized MIMO features. Furthermore, we show how to build an IEEE 802.11n indoor testbed capable of multi-hop communication. In an 8-hop chain topology, we observe that channel bonding nearly doubles the throughput for any fixed path length. The mean aggregate size in number of frames at each node is also doubled by channel bonding. The aggregate size decreases with increasing path length. Limiting the aggregate size severely impacts throughput both on single and multi-hop paths. The throughput degrades as the path length is increased as in legacy IEEE 802.11a/b/g. We believe that these findings will enhance the understanding of the performance of IEEE 802.11n in multi-hop networks.

Stream surfaces are an intuitive approach to represent 3D vector fields. In many cases, however, they are challenging objects to visualize and to understand, due to a high degree of self-occlusion. Despite the need for adequate rendering methods, little work has been done so far in this important research area. In this paper, we present an illustrative rendering strategy for stream surfaces. In our approach, we apply various rendering techniques, which are inspired by the traditional flow illustrations drawn by Dallmann and Abraham \& Shaw in the early 1980s. Among these techniques are contour lines and halftoning to show the overall surface shape. Flow direction as well as singularities on the stream surface are depicted by illustrative surface streamlines. ;To go beyond reproducing static text book images, we provide several interaction features, such as movable cuts and slabs allowing an interactive exploration of the flow and insights into subjacent structures, e.g., the inner windings of vortex breakdown bubbles. These methods take only the parameterized stream surface as input, require no further preprocessing, and can be freely combined by the user. We explain the design, GPU-implementation, and combination of the different illustrative rendering and interaction methods and demonstrate the potential of our approach by applying it to stream surfaces from various flow simulations. ;