Bounded-time fault-tolerant rule-based systems

Two systems concepts are introduced: bounded response-time and self-stabilization in the context of rule-based programs. These concepts are essential for the design of rule-based programs which must be highly fault tolerant and perform in a real time environment. The mechanical analysis of programs for these two properties is discussed. The techniques are used to analyze a NASA application

Opportunities and obligations for physical computing systems

The recent confluence of embedded and real-time systems with wireless, sensor, and networking technologies is creating a nascent infrastructure for a technical, economic, and social revolution. Based on the seamless integration of computing with the physical world via sensors and actuators, this revolution will accrue many benefits. Potentially, its impact could be similar to that of the current Internet. We believe developers must focus on the physical, real-time, and embedded aspects of pervasive computing. We refer to this domain as physical computing systems. For pervasive computing to achieve its promise, developers must create not only high-level system software and application solutions, but also low-level embedded systems solutions. To better understand physical computing\u27s advantages, we consider three application areas: assisted living, emergency response systems for natural or man-made disasters, and protecting critical infrastructures at the national level

On the Feasibility of Linear Discrete-Time Systems of the Green Scheduling Problem

Peak power consumption of buildings in large facilities like hospitals and universities becomes a big issue because peak prices are much higher than normal rates. During a power demand surge an automated power controller of a building may need to schedule ON and OFF different environment actuators such as heaters and air quality control while maintaining the state variables such as temperature or air quality of any room within comfortable ranges. The green scheduling problem asks whether a scheduling policy is possible for a system and what is the necessary and sufficient condition for systems to be feasible. In this paper we study the feasibility of the green scheduling problem for HVAC(Heating, Ventilating, and Air Conditioning) systems which are approximated by a discrete-time model with constant increasing and decreasing rates of the state variables. We first investigate the systems consisting of two tasks and find the analytical form of the necessary and sufficient conditions for such systems to be feasible under certain assumptions. Then we present our algorithmic solution for general systems of more than 2 tasks. Given the increasing and decreasing rates of the tasks, our algorithm returns a subset of the state space such that the system is feasible if and only if the initial state is in this subset. With the knowledge of that subset, a scheduling policy can be computed on the fly as the system runs, with the flexibility to add power-saving, priority-based or fair sub-policies

Architecture of a Cyberphysical Avatar

REACTION 2012. 1st International workshop on Real-time and distributed computing in emerging applications. December 4th, 2012, San Juan, Puerto Rico.This paper introduces the concept of a cyberphysical avatar which is defined to be a semi-autonomous robotic system that adjusts to an unstructured environment and performs physical tasks subject to critical timing constraints while under human supervision. Cyberphysical avatar integrates the recent advance in three technologies: body-compliant control in robotics, neuroevolution in machine learning and QoS guarantees in realtime communication. Body-compliant control is essential for operator safety since cyberphysical avatars perform cooperative tasks in close proximity to humans. Neuroevolution technique is essential for ”programming” cyberphysical avatars inasmuch as they are to be used by non-experts for a large array of tasks, some unforeseen, in an unstructured environment. QoS-guaranteed realtime communication is essential to provide predictable, boundedtime response in human-avatar interaction. By integrating these technologies, we have built a prototype cyberphysical avatar testbed

Incorporating Resource Safety Verification to Executable Model-based Development for Embedded Systems

This paper formulates and illustrates the integration of resource safety verification into a design methodology for development of verified and robust real-time embedded systems. Resource-related concerns are not closely linked with current xUML model-based software development although they are critical for embedded systems. We describe how to integrate resource analysis techniques into the early phase of an xUML-based development cycle. Our hybrid framework for resource safety verification combines static resource analysis and runtime monitoring. A case study based on an embedded controller for satellite simulation, TableSat, illustrates the benefits obtained by incorporating resource verification into design and combining static analysis and runtime monitoring. 1

Advances in Real-Time Database Systems Research Special Section on RTDBS of ACM SIGMOD Record 25(1), March 1996.

A Real-Time DataBase System (RTDBS) can be viewed as an amalgamation of a conventional DataBase Management System (DBMS) and a real-time system. Like a DBMS, it has to process transactions and guarantee ACID database properties. Furthermore, it has to operate in real-time, satisfying time constraints imposed on transaction commitments. A RTDBS may exist as a stand-alone system or as an embedded component in a larger multidatabase system. The publication in 1988 of a special issue of ACM SIGMOD Record on Real-Time DataBases signaled the birth of the RTDBS research area -- an area that brings together researchers from both the database and real-time systems communities. Today, almost eight years later, I am pleased to present in this special section of ACM SIGMOD Record a review of recent advances in RTDBS research. There were 18 submissions to this special section, of which eight papers were selected for inclusion to provide the readers of ACM SIGMOD Record with an overview of current and future research directions within the RTDBS community. In this paper [below], I summarize these directions and provide the reader with pointers to other publications for further information. -Azer Bestavros, Guest Edito

The Objectization Problem - What It Is And What Can be Done About It

let us understand the problem. 2. The Objectization Problem In order to transform an application requirements into operational software, the computational requirements of the application must eventually be mapped into a set of architectural units. The traditional architectural units are those supplied by the operating system: processes and files. In the era of object-oriented programming, the architectural unit is the object which comprises of a set of methods and a non-shared data space on which the methods of the object operate. We call the mapping of application requirements into objects the objectization problem. In the context of the objectization, the object architectural unit can be seen to serve at least three different purposes which might conflict with one another. Specifically, an #################################### + Supported by a research grant from the Office of Naval Research under ONR contract number N00014-94-1