The structural and electronic properties of the hydrides of silicene and germanene have been studied using ab initio calculations. The trend for the M–H (M= C, Si, and Ge) bond lengths, and corresponding bond energies, is consistent with the atomic size trend, and comparable to those of MH4 hydrides. Band structures were also obtained for the buckled configuration, which is the stable form for both silicene and germanene. Upon hydrogenation, both silicane (indirect gap) and germanane (direct gap) are semiconducting.

In this paper, we describe a tool-set for managing the configuration and management of large-scale networks. In particular, we focus on managing limited processing and communication resources for coordinated network cyber-defense applications. Our implementation encompasses the complete cycle, from initial network modeling and extraction of the relevant constraints, through translation into a formal constraint model, and finally the application of a Linear Programming solver to determine feasibility. This system has been demonstrated on realistic cyber-defense network models provided by domain experts, as well as on automatically-generated models, used to explore the scaling behavior of the system.

We propose a reference architecture aimed at supporting the safety and security of medical devices. The ISOSCELES (Intrinsically Secure, Open, and Safe Cyber-Physically Enabled, Life-Critical Essential Services) architecture is justified by a collection of design principles that leverage recent advances in software component isolation based on hypervisor and other separation technologies. The instantiation of the architecture for particular medical devices is supported by a development process based on Architecture Analysis and Design Language. The architecture models support safety and security analysis as part of a broader risk management framework. The models also can be used to derive skeletons of the device software and to configure the platform’s separation policies and an extensive set of services. We are developing prototypes of the architecture and example medical device instantiations on low-cost boards that can be used in product solutions. The prototype and supporting development and assurance artifacts are being released under an open-source license.

Time series data has been exploited for use with Case Based Reasoning (CBR) in many applications. We present a novel application of CBR that combines intelligent tutoring using Augmented Reality (AR) and prediction. The MonitAR system, presented in this paper, is intended for use as an intelligent guidance system for astronauts conducting complex procedures during periods of a communication time delay or blackout from Earth. Our approach takes advantage of the relational nature of time-series data to detect a task that the user is completing and diagnose the issue when the user is about to make a mistake.

A communications system is provided that includes a communications scheduler adapted to receive messages from a plurality of message sources and sensors. The messages comprise human and generated messages. The sensors comprise situational, neurophysiological and physiological sensors. The cognitive state profile processing unit receives sensor data and produces a current cognitive state profile for the user. The communications scheduler includes a context manager that receives outputs from the plurality of sensors, monitors a current user’s tasks, and retains information about the user’s environment, a message characterization unit that characterizes the messages using the attributes of the message, outputs from the sensors, and the user’s specific baseline profile data and a presentation unit that receives the characterized messages, the cognitive state profile, and context information and queues the characterized messages into a prioritized message list and presents the message list to the user via the display unit.

While creating a software suite of ontology tools for operations, we encountered several reasoner performance scaling issues. This paper describes the symptoms, the diagnosis, and the mitigation strategies used.

This thesis documents several new developments in the theory of parsing, and also the practical value of their implementation in the Copper parser generator.
The most widely-used apparatus for syntactic analysis of programming languages consists of a scanner based on deterministic finite automata, built from a set of regular expressions called the lexical syntax, and a separate parser, operating on the output of this scanner, built from a context-free grammar and utilizing the LALR(1) algorithm.

While the LALR(1) algorithm has the advantage of guaranteeing a non-ambiguous parse, and the approach of keeping the scanner and parser separate make the compilation process more clean and modular, it is also a brittle approach. The class of grammars that can be parsed with an LALR(1) parser is not closed under grammar composition, and small changes to an LALR(1) grammar can remove the grammar from the LALR(1) class. Also, the separation of scanner and parser prevent the use, in any organized way of parser context to resolve ambiguities in the lexical syntax.

One area in which both of these drawbacks pose a particular problem is that of parsing embedded and extensible languages. In particular, it forms one of the last major impediments to the development of an extensible compiler in which language extensions are imported and composed by the end user (programmer) in an analogous manner to the way libraries are presently imported. This is due not only to the problem of the LALR(1) grammar class not being closed under composition, but to the very real possibility that the lexical syntax of two different extensions will clash, making it impossible to construct a scanner without extensive manual resolution of ambiguities, if at all.

This thesis presents three innovations that are a large step towards eliminating parsing as an Achilles’ heel in this application. Firstly, it describes a new algorithm of scanning called context-aware scanning, in which the scanner at each scan is made aware of what sorts of tokens are recognized as valid by the parser at that point. By allowing the use of parser context in the scanner to disambiguate, context-aware scanning makes the specification of embedded languages much simpler — instead of specifying a scanner that must explicitly switch “modes” to scan on the different embedded languages, one simply compiles a context-aware scanner from a single lexical specification, which has implicit “modes” to scan properly on each embedded language. Similarly, in an extensible language, this puts a degree of separation between the lexical syntax of different language extensions, so that any clashes of this sort will not be an issue.

Secondly, the thesis describes an analysis that operates on grammar extensions of a certain form, and can recognize their membership in a class of extensions that can be composed with each other and still produce a deterministic parser—enabling end-users to compose extensions written by different language developers with this guarantee of determinism. The analysis is made practical by context-aware scanning, which ensures a lack of lexical issues to go along with the lack of syntactic nondeterminism. It is this analysis — the first of its kind — that is the largest step toward realizing the sort of extensible compiler described above, as the writer of each extension can test it independently using the analysis and thus resolve any lexical or syntactic issues with the extension before the end user ever sees it.

Thirdly, the thesis describes a corollary of this analysis, which allows extensions that have passed the analysis to be distributed in parse table form and then composed on-the-fly by the end users, with the same guarantee of determinism. Besides expediting the operation of composition, this also enables the use of the analysis in situations where the writer of a language or language extension does not want to release its grammar to the public.

Finally, the thesis discusses how these approaches have been implemented and made practical in Copper, including runtime tests, implementations and analyses of real-world grammars and extensions.

A device to prevent, detect and respond to one or more security threats between one or more controlled hosts and one or more services accessible from the controlled host. The device determines the authenticity of a user of a controlled host and activates user specific configurations under which the device monitors and controls all communications between the user, the controlled host and the services. As such, the device ensures the flow of only legitimate and authorized communications. Suspicious communications, such as those with malicious intent, malformed packets, among others, are stopped, reported for analysis and action. Additionally, upon detecting suspicious communication, the device modifies the activated user specific configurations under which the device monitors and controls the communications between the user, the controlled host and the services.

The Unified Cross Domain Management Office (UCDMO) states that its mission is to provide coordination and oversight for the cross domain community’s vision of “secur[ing] cross domain access to and sharing of timely and trusted information, creating a seamless Enterprise that enables decision advantage.” The UCDMO defines three types of cross domain solution (CDS) — transfer, access and multi-level — to satisfy this vision.
The transfer CDS, or guard, moves information securely between software applications running in different information security domains. Since the guard must approve all information flows between domains, it is traditionally deployed on a standalone computer host that provides the only physical link between the domains’ networks. This deployment strategy ensures that the guard cannot be bypassed. Unfortunately, as the demand for sharing increases, this strategy can prove costly.  Data centers, for example, may charge more for custom guard hardware that cannot be reallocated easily for other uses

A graph G with q edges is said to be harmonious if there is an injection f  from the vertices of G to the group of integers modulo q such that when each edge xy is assigned the label f (x) + f (y) (mod q), the resulting edge labels are distinct. If G is a tree, exactly one label may be used on two vertices. Over the years, many variations of harmonious labelings have been introduced.
We study a variant of harmonious labeling. A function f  is said to be a properly even harmonious labeling of a graph G with q edges if f  is an injection from the vertices of G to the integers from 0 to 2 (q-1) and the induced function f*  from the edges of G to 0,2,…,2 (q-1) defined by f* (xy) = f (x) + f (y) (mod 2q) is bijective. We investigate the existence of properly even harmonious labelings of families of disconnected graphs with one of C3, C4, K4 or W4as a component.