In recent years there has been a confluence between different fields addressing the broad field of embedded computer systems (cyber-physical systems). Traditional microcontroller-based systems have become more capable and now frequently feature 32-bit processors with networking capabilities. Single-board computers have shrunk to credit-card size and low-cost systems are available-significantly overlapping the application domain of microcontroller systems and, thirdly, mobile platforms (smartphones, tablets, e-readers etc.) also share many characteristics of these systems and overlap their design and application domains. These systems each have their own design communities, tools and standard approaches. However their commonality and overlapping application domains indicate that they share common design problems. The evolution into newer application areas also brings new problems. The situation becomes more complex when these systems are integrated into larger diverse systems.Design approaches and design problems for these different types of embedded system are reviewed. Overlapping and nonoverlapping characteristics and design issues are analyzed. A comprehensive design approach tailored to these cyber-physical systems is proposed. The comprehensive approach addresses design issues not only for all three of the overlapping fields but also systems that incorporate aspects from multiple fields. It also includes factors sometimes neglected when systems are developed within their own narrower design domains.One of the findings of this investigation is that design in this domain requires a diverse set of skills, usually only found in multi-disciplinary teams. One discipline that is needed but has not traditionally contributed much in this domain is Information Technology. Another finding is that designers trained in the IT discipline with a systems-oriented approach have specific design skills that are necessary for successful design of these diverse systems.

In 2-dimensional geometric constraint solving, graph-based techniques are a dominant approach, particularly in CAD context. These methods transform the geometric problem into a graph which is decomposed into small sub-graphs. Each one is solved, separately, and the final solution is obtained by recomposing the solved sub-graphs. To the best of our knowledge, there is no random geometric constraint graph generator so far. In this paper, we introduce a simple, but efficient generator that produces any possible geometric configuration. It would be parameterized to generate graphs with some desirable proprieties, like highly or weakly decomposable graphs, or restricting the generated graph to a specific class of geometric configuration. Generated graphs can be used as a benchmark to make consistent tests, or to observe algorithm behaviour on the geometric constraint graphs with different sizes and structural properties. We prove that our generator is complete and suitable for two main classes of solving approaches.

Advances in computing technologies have provided the needed tools to transform traditional single user architecture Computer Aided Applications (CAx) to multi-user collaborative CAx architectures that supports simultaneous concurrency. To allow for a successful deployment in a corporate enterprise environment, the multi-user CAx architecture will require reliable security mechanisms to ensure protection of intellectual property. In this paper we propose mechanisms for securing user access and communications in a multi-user collaborative CAx software system. The proposed security solution is currently under development and is being tested on a collaborative multi-user version of a popular commercial CAD application.

Cyber-Physical Systems (CPS) or Embedded Systems are now so wide spread that we see applications in almost every aspect of our everyday activities. Application fields include industrial process control, health care, transportation, financial transaction systems, building security systems, home electronics, and automobiles, among others. The "Physical" aspect of CPS indicates that these systems interact mainly with the physical world and thus can significantly impact human and environmental safety as well as large physical infrastructure systems. CPS failure can therefore have catastrophic consequences. It is thus very important that CPS operate in a safe, reliable and secure manner. While these systems have seen a lot of technological improvements resulting in increased functionality, the issue of security has been a low priority in their design, thus exposing them to several security threats. If we are to benefit fully from the many applications of CPS then security needs to take a central role in their design. The challenges of security design for CPS are aggravated by the lack of standardization in hardware, operating systems, networking and the diverse physical environment. Addressing such challenges needs a strong collaboration between those skilled in CPS component design as well as those skilled in security and other aspects of these complex systems. This study includes an analysis of the available literature and design practices in several CPS application fields, with an emphasis on design for security. The Information Technology community has a rich background in security analysis, although not generally applied to CPS design. Thus a security analysis methodology for CPS was developed from recognized security analysis techniques for conventional computing. Assets, security threats and risks are analyzed relative to a CPS environment. Current security solutions are presented and compared. We discuss evolutionary changes of CPS leading to their growing importance within computing disciplines and their increasing role in large, heterogeneous distributed systems. Finally the integrative nature of CPS design is discussed and the role of Information Technology as a major contributor to CPS design for security is emphasized.