Current Issue : April - June Volume : 2011 Issue Number : 2 Articles : 4 Articles
Power management is addressed in the context of embedded systems from energy-aware design to energy-efficient implementation. A set of mechanisms specifically conceived for this scenario is proposed, including a power management API defined at the level of user-visible system components, the infrastructure necessary to implement that API (namely, battery monitoring, accounting, autosuspend, and autoresume), an energy-event propagation mechanism based on Petri nets and implemented with aspect-oriented programming techniques, and an autonomous power manager build upon the proposed API and infrastructure. These mechanisms are illustrated and evaluated using realistic wireless sensor network cases that sustain comparisons with other proposals at each of the considered levels. As a result, this paper has its main contribution on the introduction of a comprehensive and systematic way to deal with power management issues in resource-constrained, battery-operated systems....
We propose theoretically a spectroscopic ellipsometer in which the polarizer and the analyzer are rotating synchronously in the same direction with the same angular speed. The light intensity received by the detector contains four components, one dc and three AC terms, with frequencies of 2ω, 4ω, and 6ω. The main advantage of the proposed ellipsometer is that: one can extract the ellipsometric parameters ψ and Δ from the AC Fourier coefficients without relying on the dc component which is considered to be a serious problem in rotating-analyzer or -polarizer ellipsometers. This allows measurements in semi-dark room without worrying about stray light problems, dark currents in detectors, and long term fluctuations in light sources. The results from the simulated spectra of the complex refractive index of c-Si, and Au are presented. The noise effect on the proposed ellipsometer was simulated and plotted for the two samples....
With rapid advancements in sensing, networking, and computing technologies, recent years have witnessed the emergence of cyber-physical systems (CPS) in a broad range of application domains. CPS is a new class of engineered systems that features the integration of computation, communications, and control. In contrast to general-purpose computing systems, many cyber-physical applications are safety critical. These applications impose considerable requirements on quality of service (QoS) of the employed networking infrastruture. Since IEEE 802.15.4 has been widely considered as a suitable protocol for CPS over wireless sensor and actuator networks, it is of vital importance to evaluate its performance extensively. Serving for this purpose, this paper will analyze the performance of IEEE 802.15.4 standard operating in different modes respectively. Extensive simulations have been conducted to examine how network QoS will be impacted by some critical parameters. The results are presented and analyzed, which provide some useful insights for network parameter configuration and optimization for CPS design....
This paper investigates the assimilation of embodied virtuality with parametric modelling to inform various stages of architectural design. Embodied virtuality is a term introduced by Mark Weiser in 1991 to describe the era of ubiquitous computing. Traditionally, the data used as input to a parametric model needs to co-exist in the digital world, stored in an archive or file system of our computer. However, with the proliferation of sensor and mobile devices, data can now be found everywhere in the physical world and the boundaries between the physical and the digital has become blurred. There is a need to integrate the real world and the digital information space for designing parametric models. The assimilation of digital data from the physical world with the existing CAD tools will create a synergy between form finding and form making. This paper introduces the notion of form fostering, which stands in between physical form making and digital form finding. Form fostering takes various inputs from the physical world to inform a parametric model or to actuate a physical model in the built environment. We present early experiments of Form Fostering, which include the use of a Wii Remote, an Arduino processing board, servo actuators and a camera as haptic input and interaction devices. The potential benefits of designing in embodied virtuality are significant since designers can get real-time input from both the physical context and from interaction with the parametric model....
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