Patch models and their applications to multivehicle command and control.

We introduce patch models, a computational modeling formalism for multivehicle combat domains, based on spatiotemporal abstraction methods developed in the computer science community. The framework yields models that are expressive enough to accommodate nontrivial controlled vehicle dynamics while being within the representational capabilities of common artificial intelligence techniques used in the construction of autonomous systems. The framework allows several key design requirements of next-generation network-centric command and control systems, such as maintenance of shared situation awareness, to be achieved. Major features include support for multiple situation models at each decision node and rapid mission plan adaptation. We describe the formal specification of patch models and our prototype implementation, i.e., Patchworks. The capabilities of patch models are validated through a combat mission simulation in Patchworks, which involves two defending teams protecting a camp from an enemy attacking team.     

Architecture, Infrastructure, and Broadband Civic Network Design: An Institutional View

Cultural values frame architectures, and architectures motivate infrastructures-by which we mean the foundational telecommunications and Internet access services that software applications depend on. Design is the social process that realizes architectural elements in an infrastructure. This process is often a conflicted one where transformative visions confront the realities of entrenched power, where innovation confronts pressure from institutionalized interests and practices working to resist change and reproduce the status quo in the design outcome. We use this viewpoint to discuss design aspects of the Urban-net, a broadband civic networking case. Civic networks are embodiments of distinctive technological configurations and forms of social order. In choosing some technological configurations over others, designers are favoring some social structural configurations over alternatives. To the extent that a civic network sets out to reconfigure the prevailing social order (as was the case in the Urban-net project considered here), the design process becomes the arena where challengers of the prevailing order encounter its defenders. In this case the defenders prevailed, and the design that emerged was conservative and reproduced the status quo. What steps can stakeholders take so that the project’s future development is in line with the original aim of structural change? We outline two strategies. We argue the importance of articulating cultural desiderata in an architecture that stakeholders can use to open up the infrastructure to new constituents and incremental change. Next, we argue the importance of designing the conditions of design. The climate in which social interactions occur can powerfully shape design outcomes, but this does not usually figure in stakeholders’ design concerns.     

Minimizing Phase Noise Variation in CMOS Ring Oscillators

The variation of phase noise across the frequency of operation of a CMOS ring oscillator is described analytically. The delay element of the ring oscillator considered comprises of a source-coupled differential pair with an active load element. In this circuit topology where the frequency of oscillation is varied by changing the resistance of the load, theory derived in this work predicts that phase noise will remain constant if constant output swing is maintained. Such an oscillator is designed in a 0.5 m CMOS process and the simulation results verify the theoretical analysis. Consequently, an oscillator design methodology is provided that dramatically reduces the phase noise optimization problem to just one frequency within the oscillator's output frequency range.     

Adaptivity in hybrid-Trefftz finite element formulation

With the advent of computer aided design (CAD), the development of fully or semi-automated procedures by which a solution warranting the specified accuracy can most efficiently be reached has become a necessity. It is now of utmost interest to investigate finite element (FE) formulations offering a simple form of adaptivity, easy to implement. The present study (which is a sequel to an earlier paper¹ on error estimation by the authors) identifies as a particularly promising approach of attaining this goal the p-method associated with the so-called hybrid-Trefftz FE model.² Based on a simple stress error estimator¹ and prior knowledge of the convergence rate, the solution warranting specified stress accuracy may be reached in a single trial by suitably respecifying just one parameter in the input data. The reported approach has successfully been implemented into the general purpose FE program SAFE³ and its high efficiency is illustrated in the paper through practical applications involving corner singularities and stress concentrations.     

An optimal control analysis for baseflow externalities in an interconnected lake–aquifer system

Groundwater resources play a vital role in regional growth and development. From a sustainability viewpoint, it is, however, imperative to ensure that groundwater extractions do not lead to deleterious environmental consequences. The interconnections between groundwater in the aquifers and surface water bodies are increasingly being recognized in recent times and groundwater discharges to surface water bodies are critical to maintain water levels and water quality during summer months and periods of drought. Excessive groundwater withdrawals can cause water levels in streams and lakes to drop below unacceptable levels. This phenomenon is referred to as baseflow externality in this study. The primary goal of this investigation was to develop a mathematical model useful to assess policy options pertaining to groundwater withdrawals considering baseflow externalities. The model was used to evaluate five wide-ranging policy options that emphasize economic gains and ecological impacts to different levels. The weak sustainability policy option represents a reasonable compromise and identifies groundwater pumping that maximizes economic benefits while maintaining acceptable water levels in an interconnected lake. However, the implementation success of this approach hinges on achieving consensus among stakeholders and the ability to find reliable additional water supplies at the end of the planning period. The developed model can be a useful tool for facilitating stakeholder discussions that foster participatory groundwater management.     

Light-Weight Frame Wall Assemblies: Parameters for Consideration in Fire Resistance Performance-Based Design

With the advent of performance-based codes and fire safety design options, it is essential to determine parameters that affect the fire-resistance performance of assemblies. This paper presents the results of 17 full-scale fire-resistance tests conducted as part of a major industry-government research program investigating parameters that affect the fire-resistance performance of light-weight frame wall assemblies. These include the effects of insulation type, insulation width between studs, resilient channel location, gypsum board thickness, number of gypsum board layers, glass fiber in the gypsum board core, gypsum board mass per unit area, and stud type for light-weight frame wall assemblies finished with gypsum board. The effects of these parameters on the fire resistance are discussed.     

An espoused cultural perspective to understand continued intention to use mobile applications: a four-country study of mobile social media application usability

As most mobile applications are tailored for worldwide consumption, it is a significant challenge to develop applications that satisfy individuals with various cultural backgrounds. To address this issue, we drew on a recently developed conceptualization and associated instrument of mobile application usability to develop a model examining the impact of mobile social media application usability on continued intention to use. Drawing on Hofstede’s five cultural values, we incorporated espoused cultural values of masculinity/femininity, individualism/collectivism, power distance, uncertainty avoidance, and long-term orientation into our model as moderators. To test the model, we collected data from 1,844 consumers in four countries – the U.S., Germany, China, and India – who use mobile social media applications on their smartphones. The results provided support for the role of espoused national cultural values in moderating the impact of mobile social media application usability on continued intention to use and the model, with espoused cultural values explaining significantly more variance in continued intention to use (i.e., 38%) than the main effects-only model (i.e., 19%). Interestingly, our results demonstrated that culture at the national level did not play a significant role in affecting the relationship between usability constructs and continued intention to use, thus underscoring the importance of espoused culture.     

Glycerol Esters from Real Waste Cooking Oil Using a Robust Solid Acid Catalyst

Notwithstanding the food-for-fuel debate, turning waste cooking oil and fat (WCO) into a valuable product is a classic example of green chemistry. We demonstrate that sulfated zirconia and lanthanum-supported sulfated zirconia are good catalysts for the esterification of WCO free fatty acids (FFAs) with glycerol, giving high-value monoglycerides. Various catalysts were first screened using palmitic acid as a model FFA. Subsequently, six 10-kg batches of actual WCO were collected from commercial cookeries over a period of 28 weeks, pre-treated in a purpose-built decanter and esterified with industrial grade glycerol using heterogeneous catalysis. Good yield and turnovers were obtained. The pre-treatment stage and the catalytic esterification experiments are described and discussed.