Information content analysis of combined lidar-polarimeter retrievals to improve aerosol remote sensing accuracy

Aerosols are small particles suspended in the atmosphere which affect global climate change via scattering and absorbing sunlight and serving as cloud condensation nuclei. Moreover, the prevalence of some anthropogenic and toxic aerosols has a direct adverse impact on public health. At present, aerosols remain the greatest source of uncertainty for radiative forcing. Though accurate characterization of spatially and temporally varying aerosols is difficult, two powerful remote sensing techniques, polarimetric and lidar measurements, have the complementary strengths of resolving column-effective and vertical distributions of aerosol properties, respectively. Vigorous development of these instruments has sparked our interest in 1) their collocation on ground-based, airborne, and space-borne platforms and 2) developing more efficient, versatile forward and inverse models that make use of combined lidar and polarimetric data to enhance aerosol remote sensing accuracy. In our effort to address target 2, the information content analysis (ICA) method is adopted in this study. It uses a priori information of speciated aerosol characteristics and various assumptions of measurement uncertainties as input. Combined with the use of a light scattering model and a radiative transfer model, lidar and polarimetric signals are simulated. The retrieval uncertainties of a suite of aerosol-related geophysical variables (GVs) are output by ICA, which allows us to explore the dependence of GV retrieval capabilities on a priori knowledge of aerosol properties and instrument accuracy. We analyze results to 1) check whether aerosol GV uncertainty thresholds established by NASA’s Aerosol and Cloud, Convection and Precipitation (ACCP) mission are met by different lidar and polarimetric instrument configurations and 2) identify a cost-effective, yet accurate, instrument combination for future missions. Five different methods are used to perturb a priori knowledge of state vector and measurement uncertainties across seven different lidar and/or polarimeter instrument configurations. Calculated GV uncertainties output by our model are compared to threshold GV retrieval uncertainties established by ACCP’s Science and Applications Traceability Matrix (SATM). Results show clear impact of a priori knowledge on retrieval capabilities as well as the importance of specific measurements to accurate retrievals of the GVs considered. Across results, the 2β 2α 1β_attn lidar and polarimeter (L6+POL) instrument combination consistently showed superior abilities of retrieving the GVs considered within SATM-prescribed uncertainty ranges

Managing Vulnerabilities of Tactical Wireless RF Network Systems: A Case Study

Organisations and individuals benefit when wireless networks are protected. After assessing the risks associated with wireless technologies, organisations can reduce the risks by applying countermeasures to address specific threats and vulnerabilities. These countermeasures include management, operational and technical controls. While these countermeasures will not prevent all penetrations and adverse events, they can be effective in reducing many of the common risks associated with wireless RF networks. Among engineers dealing with different scaled and interconnected engineering systems, such as tactical wireless RF communication systems, there is a growing need for a means of analysing complex adaptive systems. We propose a methodology based on the systematic resolution of complex issues to manage the vulnerabilities of tactical wireless RF systems. There are is a need to assemble and balance the results of any successful measure, showing how well each solution meets the system’s objectives. The uncertain arguments used and other test results are combined using a form of mathematical theory for their analysis. Systems engineering thinking supports design decisions and enables decision‐makers to manage and assess the support for each solution. In these circumstances, complexity management arises from the many interacting and conflicting requirements of an increasing range of possible parameters. There may not be a single ‘right’ solution, only a satisfactory set of resolutions which this system helps to facilitate. Smart and innovative performance matrixes are introduced using a mathematical Bayesian network to manage, model, calculate and analyse all the potential vulnerability paths in wireless RF networks

Explaining the effectiveness of performance-based logistics: a quantitative examination

The article of record as published may be located at http://dx.doi.org/10.1108/09574091111181354Purpose – Performance-based logistics (PBL) strategies are providing governments and for-profit organizations with a contractual mechanism that reduces the life cycle costs of their systems. PBL accomplishes this by establishing contracts that focus on the delivery of performance not parts. PBL establishes a metric based governance structure where suppliers make more profit when they invest in logistics process improvements, or system redesign, that reduces total cost of ownership. While work has been done to outline an overall PBL theoretical framework, the underlying theory explaining the enablers that lead to organizational and team-level, team-goal alignment associated with the PBL governance structure requires testing. The purpose of this paper is to quantitatively test previously posited relationships between enablers of PBL and PBL effectiveness. An additional objective is to explore any differences in PBL effectiveness between different business sectors.This material is based upon work supported by the Naval Postgraduate School Acquisition Research Program under Grant No. N00244-10-1-0074

A Case Report of Candida albicans Costochondritis after a Complicated Esophagectomy

This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially.We present an unusual case of Candida albicans costochondritis after a complicated Ivor Lewis esophagectomy. This case exhibits that pain, erythema, and swelling over the costal cartilages should alert the possibility of infective costochondritis, especially in a postoperative patient. If a fungal agent is identified, aggressive surgical debridement and early commencement of antifungal therapy are likely determinants for a satisfactory outcome

Fabrication system, method and apparatus for microelectromechanical devices

A fabrication system and method of fabrication for producing microelectromechanical devices such as field-effect displays using thin-film technology. A spacer is carried at its proximal end on the surface of a substrate having field-effect emitters with the spacer being enabled for tilting movement from a nested position to a deployed position which is orthogonal to the plane of the substrate. An actuator is formed with one end connected with the substrate and another end connected with spacer. The actuator is made of a shape memory alloy material which contracts when heated through the material's phase-change transition temperature. Contraction of the actuator exerts a pulling force on the spacer which is tilted to the deployed position. A plurality of the spacers are distributed over the area of the display. A glass plate having a phosphor-coated surface is fitted over the distal ends of the deployed spacer

Scale development and validation of Transaction Cost Economics typology for contracts: A systems thinking approach

A variety of contract typologies that exist in the literature are helpful in the exploration of different approaches in contractual relations, but only when measured with the right instruments. Although Transaction Cost Economics (TCE) has a distinct, high-level, and abstract typology for contracts, it still lacks a measurement scale. In this paper, a measurement scale for the TCE contract typology (classical, neo-classical, and relational contracts) was developed and validated, using systems thinking approach and experimental design to contribute to the empirical tests of TCE within the contracting realm. First, the antecedents of contract selection within the TCE literature were analyzed using the systemigram technique to visualize and parse out complex relationships that lead to contract selection. The analysis of the TCE Systemigram helped the development of the scale and revealed the need to revisit the risk neutrality assumption embedded in TCE. Second, a measurement scale for the TCE contract typology (classical, neo-classical, and relational contracts) was developed adhering to the original texts of seminal papers and reviews from the TCE literature. Third, the 14-item measurement scale was validated using a series of three vignette-based experimental studies