Entangled photon apparatus for the undergraduate laboratory

We present detailed instructions for constructing and operating an apparatus to produce and detect polarization-entangled photons. The source operates by type-I spontaneous parametric downconversion in a two-crystal geometry. Photons are detected in coincidence by single-photon counting modules and show strong angular and polarization correlations. We observe more than 100 entangled photon pairs per second. A test of a Bell inequality can be performed in an afternoon.Comment: 6 pages, 9 figure

Bi-Directional Safety Analysis for Product-Line, Multi-Agent Systems

Abstract. Safety-critical systems composed of highly similar, semi-autonomous agents are being developed in several application domains. An example of such multi-agent systems is a fleet, or “constellation ” of satellites. In constellations of satellites, each satellite is commonly treated as a distinct autonomous agent that must cooperate to achieve higher-level constellation goals. In previous work, we have shown that modeling a constellation of satellites or spacecraft as a product line of agents (where the agents have many shared commonalities and a few key differences) enables reuse of software analysis and design assets. We have also previously developed efficient safety analysis techniques for product lines. We now propose the use of Bi-Directional Safety Analysis (BDSA) to aid in system certification. We extend BDSA to product lines of multi-agent systems and show how the analysis artifacts thus produced contribute to the software’s safety case for certification purposes. The product-line approach lets us reuse portions of the safety analysis for multiple agents, significantly reducing the burden of certification. We motivate and illustrate this work through a specific application, a product-line, multi-agent satellite constellation

Shear-wave vibrational directions and related fault movements in Southern California Earthquakes

Vibrational directions of direct shear waves from a number of small local earthquakes in southern California, recorded at Pasadena and Riverside, are determined and related to corresponding faulting at the source. A theoretical relationship between wave vibrational directions and fault displacements is proposed. Directions of SV and SH motions from various fault types are adduced from this relationship. Observations of initial shear wave motions indicate generally consistent SH displacements, usually less consistent SV displacements, and ratios of SV/SH which usually vary widely. Polarization of SH waves is indicated; that of SV wave, suggested. The entire shear wave is probably approximately plane-polarized. The results of this study indicate that horizontal components of faulting in southern California usually follow the same general direction, whereas vertical fault components appear to vary in direction. Comparison of observed SV and SH motions with (1) theoretical shear motions and (2) Gutenberg's (1941) observations of compressional wave impulses, provides analysis of faulting at the source. Seismic data and regional surface geology indicate a fault pattern involving, primarily, northwesterly-trending right-handed transcurrent faults in some parts of southern California, approximately east-west-trending reverse or thrust faults in other parts, and the coexistence of the two in a few localities. Simplified stress distributions in agreement with the data are discussed briefly

Entangled photons, nonlocality and Bell inequalities in the undergraduate laboratory

We use polarization-entangled photon pairs to demonstrate quantum nonlocality in an experiment suitable for advanced undergraduates. The photons are produced by spontaneous parametric downconversion using a violet diode laser and two nonlinear crystals. The polarization state of the photons is tunable. Using an entangled state analogous to that described in the Einstein-Podolsky-Rosen ``paradox,'' we demonstrate strong polarization correlations of the entanged photons. Bell's idea of a hidden variable theory is presented by way of an example and compared to the quantum prediction. A test of the Clauser, Horne, Shimony and Holt version of the Bell inequality finds $S = 2.307 \pm 0.035$, in clear contradiciton of hidden variable theories. The experiments described can be performed in an afternoon.Comment: 10 pages, 6 figure

Architecting Secure Software Systems Using an Aspect-Oriented Approach: : A Survey of Current Research

The importance of security in the development of complex software systems has increasingly become more critical as software becomes increasingly more pervasive in our everyday lives. Aspect-orientation has been proposed as a means to handle the crosscutting nature of security requirements when developing, designing and implementing security-critical applications. This paper surveys some of the approaches and contributions of integrating an aspect-oriented approach into designing and implementing secure software systems

A Privacy Policy Comparison of Health and Fitness Related Mobile Applications

AbstractMany mobile device end users believe that privacy is important when dealing with personal health-related information, but the challenge is to develop privacy policies in a meaningful way so that mobile software application developers can adequately meet the requirements of their intended end users. Comprehensive privacy policies, which meet self-regulatory guidelines of increasing transparency on data collection, are often written in a way that average mobile users cannot understand or completely ignore. This paper provides the results of a privacy policy comparison including application permissions requested and several readability metrics used to assess the current state of privacy policies in the health and fitness mobile application market. Our analysis indicates that developers may not be considering their end-users’ reading comprehension levels and specific application permissions are not adequately addressed when developers are creating their privacy policies

Formalizing generalized maps in Coq

AbstractThis paper is the first half of a two-part series devoted to an exemplary formal proof of a fundamental result in the field of geometry—the theorem of classification of surfaces—which has major implications in computer graphics. We study here the specification of generalized maps, a topological combinatory model for surfaces subdivisions. We show how we developed in Coq two fundamentally distinct formalizations of generalized maps, each based on one of the standard definitions, in a single common framework, then used this specification to prove for the first time their complete equivalence

A Grounded Theoretical and Linguistic Analysis Approach for Non-Functional Requirements Analysis

An important aspect of the requirements engineering process is the specification of traceable, unambiguous and operationalizable non-functional requirements. This remains a non-trivial task due to the lack of well-documented, systematic procedures that facilitate a structured analysis of the qualitative data that is typically the input to this activity. This research investigates the development of a procedural approach that can potentially fill this gap by incorporating procedural perspectives from Grounded Theory Method, Linguistic Analysis and the Non-Functional Requirement Framework, without significantly deviating from existing practice. This paper describes a preliminary version of this procedural approach along with empirical illustrations using data from a redesign initiative of a library website of a public university in the United States. The paper concludes with a preliminary assessment of the approach and a discussion of the contributions of the research the research