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For reactive embedded software — designed by composing existing reactive components — ensuring correctness is not straightforward. The possibility of deadlock across components, mismatch in temporal behaviors at the connected interface signals, etc., could lead to non-reactivity or subtle bugs. Behavioral interface theories have been proposed for checking compatibility of components when reactive...
Embedded software systems respond to multiple events coming from various sources -- some temporally regular (ex: periodic sampling of continuous time signals) and some intermittent (ex: interrupts, exception events etc.). Timely response to such events while executing complex computation, might require multi-threaded implementation. For example, overlapping I/O of various types of events, and computation...
We analyze the actual commuting profiles of vehicles in the US and develop a statistical model to fit the observed data. Subsequently, this model is leveraged in a simulation framework to simulate the behavior of fleets of Plug-in Electric Vehicles (PEV), analyze their impact on the grid and, compute the effective load carrying capacity (ELCC) contributed by PEVs. We develop methodologies to quantify...
The effect of integrating intermittent renewable generation such as wind and solar, as well as plug-in electric vehicles (PEVs) on a grid is an important area of study. Renewable generation depends on weather. Energy consumption, storage, and emergency usage of battery-stored power in PEVs are dependent on the spread of such vehicles in a geographical area, commute patterns, and hours of long-term...
Architecture Analysis and Design Language (AADL) is a standard that originated in the avionics domain, but is now being used in avionics and other critical distributed real-time embedded system design. AADL provides a formal notation and semantics for capturing an entire distributed platform architecture (hardware components, protocols, and software architecture annotated with properties including...
This paper presents an embedding of polychronous programs into synchronous ones. Due to this embedding, it is not only possible to deepen the understanding of these different models of computation, but, more importantly, it is possible to transfer compilation techniques that were developed for synchronous programs to polychronous programs. This transfer is nontrivial because the underlying paradigms...
The functionality of Fused multiply add (FMA) design can be formally verified by comparing its register transition level (RTL) implementation against its system level specification often modeled by C/C++ language using sequential equivalent checking (SEC). However, C-RTL SEC does not scale for FMA because of the huge discrepancy existed between the two models. This paper analyzes the dissimilarities...
We have developed a model for analyzing the system imbalance with different mixes of renewable generation (solar photovoltaic and wind) including in the presence of large pools of plug-in electric vehicles (PEVs) that participate in vehicle-to-grid and grid-to-vehicle operations. Our proposed model also identifies optimal compositions of renewable portfolios that minimize system imbalance reserve...
The post-mortem analysis of few blackouts in US and Europe concluded that the hidden failure induced tripping of distance relays is one of the primary causes of blackouts. In order to provide the distance relays with situational awareness and improve their robustness to hidden failures, a non-intrusive agent based relay supervised distance protection scheme is proposed in [1] and their results seemed...
We have developed a model to identify optimal sizes of aggregate solar PV capacity in a region that maximizes the effective load carrying capacity (ELCC) of the grid in the presence of increasing number of plug-in electric vehicles (PEVs) participating in vehicle-to-grid operations. The model has been implemented using a simulation-based framework performing the following key steps: • Compute optimal...
We performed a study of plug-in electric vehicle (PEV) vehicle-to-grid (V2G) operations to characterize the behavior of effective load carrying capacity (ELCC) contributed by the PEVs. We leveraged the V2G simulation framework developed in [1] and used wider data sets in this study to perform a broader and deeper analysis.
Polychrony, a model of computation, allows us to statically analyze safety properties from formal specifications and synthesize deterministic software for safety-critical cyber physical systems. Currently, the analysis is performed on the formal specifications through Boolean abstractions. Even though it is a sound abstraction, for more precise analysis we might have to refine the abstraction. Refining...
Polychronous specifications express concurrent, multi-clocked models which capture multiple threads of computation operating relatively asynchronous to each other. A clock of a variable in this context, is the totally ordered set of instants at which events occur on that variables. However, the notion of instant here is logical as opposed to real-time instants. The instants of different clocks may...
Intermittent and uncertain nature of power output from weather-dependent renewable energy sources like solar is a major challenge in integrating them with traditional power grids that mostly consist of reliable power sources. We have created a framework for efficiently managing the weather-related uncertainty risk of solar generators and facilitating their integration into power grids while optimizing...
For the description of reactive systems, there is a large number of languages and formalisms, and depending on a particular application or design phase, one of them may be better suited than another one. In the design of reactive systems, their integration is a key issue for a system-wide simulation, analysis and verification. In this paper, we propose clocked guarded actions as a unified intermediate...
In this paper, we propose a distributed agent based supervisory scheme to make Zone 3 relays robust to hidden failure induced tripping, facilitated by the communication network -- soon to become an integral parts of the smart grid. Possible elimination of Zone 3 relays (remote backup protection) has been studied in the recent past and these remote backup relays have been adjudged to be essential for...
In order to prevent cascading events caused by hidden failures in zone 3 relays, agent based relay architectures have been suggested in the recent past. In such architectures each zone 3 relay contains agents that require communication with other agents at various relevant relays in order to distinguish a real zone 3 event from a temporary overload. In the presence of hidden failures such temporary...
Clock gating and operand isolation are two techniques to reduce the power consumption in state-of-the-art hardware designs. Both approaches basically follow a two-step procedure: first, they statically analyze a hardware circuit to determine irrelevant computations. Second, all parts which are responsible for these computations are replaced by others that consume less power in the average case, either...
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