Illinois Institute of Technology

About: Illinois Institute of Technology is a education organization based out in Chicago, Illinois, United States. It is known for research contribution in the topics: Electric power system & Wireless network. The organization has 10188 authors who have published 21062 publications receiving 554178 citations. The organization is also known as: IIT & Illinois Tech.

Power Management of an Ultracapacitor/Battery Hybrid Energy Storage System in an HEV

Abstract: To overcome the power delivery limitations of batteries and energy storage limitations of ultracapacitors, hybrid energy storage systems, which combine the two energy sources, have been proposed. A comprehensive review of the state of the art is presented. In addition, a method of optimizing the operation of a battery/ultracapacitor hybrid energy storage system (HESS) is presented. The goal is to set the state of charge of the ultracapacitor and the battery in a way which ensures that the available power and energy is sufficient to supply the drivetrain. By utilizing an algorithm where the states of charge of both systems are tightly controlled, we allow for the overall system size to reduce since more power is available from a smaller energy storage system.

Distributed heuristics for connected dominating sets in wireless ad hoc networks

Abstract: A connected dominating set (CDS) for a graph G(V, E) is a subset V' of V, such that each node in V — V' is adjacent to some node in V', and V' induces a connected subgraph. CDSs have been proposed as a virtual backbone for routing in wireless ad hoc networks. However, it is NP-hard to find a minimum connected dominating set (MCDS). An approximation algorithm for MCDS in general graphs has been proposed in the literature with performance guarantee of 3 + In Δ where Δ is the maximal nodal degree [1]. This algorithm has been implemented in distributed manner in wireless networks [2]–[4]. This distributed implementation suffers from high time and message complexity, and the performance ratio remains 3 + In Δ. Another distributed algorithm has been developed in [5], with performance ratio of Θ(n). Both algorithms require two-hop neighborhood knowledge and a message length of Ω (Δ). On the other hand, wireless ad hoc networks have a unique geometric nature, which can be modeled as a unit-disk graph (UDG), and thus admits heuristics with better performance guarantee. In this paper we propose two destributed heuristics with constant performance ratios. The time and message complexity for any of these algorithms is O(n), and O(n log n), respectively. Both of these algorithms require only single-hop neighborhood knowledge, and a message length of O (1).

Meaningful assessment of learners' understandings about scientific inquiry—The views about scientific inquiry (VASI) questionnaire

Abstract: Helping students develop informed views about scientific inquiry (SI) has been and continues to be a goal of K-12 science education, as evidenced in various reform documents. Nevertheless, research focusing on understandings of SI has taken a perceptible backseat to that which focuses on the “doing” of inquiry. We contend that this is partially a function of the typical conflation of scientific inquiry with nature of science (NOS), and is also attributable to the lack of a readily accessible instrument to provide a meaningful assessment of learners' views of SI. This article (a) outlines the framework of scientific inquiry that undergirds the Views About Scientific Inquiry (VASI) questionnaire; (b) describes the development of the VASI, in part derived from the Views of Scientific Inquiry (VOSI) questionnaire; (c) presents evidence for the validity and reliability of the VASI; (d) discusses the use of the VASI and associated interviews to elucidate views of the specific aspects of SI that it attempts to assess; and (e) discusses the utility of the resulting rich-descriptive views of SI that the VASI provides for informing both further research efforts and classroom practice. The trend in recent reform documents, unfortunately, ignores much of the research on NOS and SI and implicitly presumes that the “doing” of inquiry is sufficient for developing understandings of SI. The VASI serves as a tool in further discrediting this contention and provides both the classroom teacher and the researcher a more powerful means for assessing learners' conceptions about essential aspects of SI, consonant with the vision set forth in the recently released Next Generation Science Standards (Achieve, Inc., 2013). © 2013 Wiley Periodicals, Inc. J Res Sci Teach 51: 65–83, 2014