Modeling and Analysis of Power Processing Systems

The feasibility of formulating a methodology for the modeling and analysis of aerospace electrical power processing systems is investigated. It is shown that a digital computer may be used in an interactive mode for the design, modeling, analysis, and comparison of power processing systems

Data Cache-Energy and Throughput Models: Design Exploration for Embedded Processors

Most modern 16-bit and 32-bit embedded processors contain cache memories to further increase instruction throughput of the device. Embedded processors that contain cache memories open an opportunity for the low-power research community to model the impact of cache energy consumption and throughput gains. For optimal cache memory configuration mathematical models have been proposed in the past. Most of these models are complex enough to be adapted for modern applications like run-time cache reconfiguration. This paper improves and validates previously proposed energy and throughput models for a data cache, which could be used for overhead analysis for various cache types with relatively small amount of inputs. These models analyze the energy and throughput of a data cache on an application basis, thus providing the hardware and software designer with the feedback vital to tune the cache or application for a given energy budget. The models are suitable for use at design time in the cache optimization process for embedded processors considering time and energy overhead or could be employed at runtime for reconfigurable architectures

The Importance of Disk Structure in Stalling Type I Migration

As planets form they tidally interact with their natal disks. Though the tidal perturbation induced by Earth and super-Earth mass planets is generally too weak to significantly modify the structure of the disk, the interaction is potentially strong enough to cause the planets to undergo rapid type I migration. This physical process may provide a source of short-period super-Earths, though it may also pose a challenge to the emergence and retention of cores on long-period orbits with sufficient mass to evolve into gas giants. Previous numerical simulations have shown that the type I migration rate sensitively depends upon the circumstellar disk's properties, particularly the temperature and surface density gradients. Here, we derive these structure parameters for 1) a self-consistent viscous-disk model based on a constant \alpha-prescription, 2) an irradiated disk model that takes into account heating due to the absorption of stellar photons, and 3) a layered-accretion disk model with variable \alpha-parameter. We show that in the inner viscously-heated regions of typical protostellar disks, the horseshoe and corotation torques of super-Earths can exceed their differential Lindblad torque and cause them to undergo outward migration. However, the temperature profile due to passive stellar irradiation causes type I migration to be inwards throughout much of the disk. For disks in which there is outwards migration, we show that location and the mass range of the "planet traps" depends on some uncertain assumptions adopted for these disk models. Competing physical effects may lead to dispersion in super-Earths' mass-period distribution.Comment: 12 pages, Submitted to Ap

Methodologies for Designing Power-Aware Smart Card Systems

Smart cards are some of the smallest computing platforms in use today. They have limited resources, but a huge number of functional requirements. The requirement for multi-application cards increases the demand for high performance and security even more, whereas the limits given by size and energy consumption remain constant. We describe new methodologies for designing and implementing entire systems with regard to power awareness and required performance. To make use of this power-saving potential, also the higher layers of the system - the operating system layer and the application domain layer - are required to be designed together with the rest of the system. HW/SW co-design methodologies enable the gain of system-level optimization. The first part presents the abstraction of smart cards to optimize system architecture and memory system. Both functional and transactional-level models are presented and discussed. The proposed design flow and preliminary results of the evaluation are depicted. Another central part of this methodology is a cycle-accurate instruction-set simulator for secure software development. The underlaying energy model is designed to decouple instruction and data dependent energy dissipation, which leads to an independent characterization process and allows stepwise model refinement to increase estimation accuracy. The model has been evaluated for a high-performance smart card CPU and an use-case for secure software is given

A case for code-representative microbenchmarks

Microbenchmarks are fundamental in the design of a microarchitecture. They allow rapid evaluation of the system, while incurring little exploration overhead. One key design aspect is the thermal design point (TDP), the maximum sustained power that a system will experience in typical conditions. Designers tend to use hand-coded microbenchmarks to provide an estimation for TDP. In this work we make the case for a systematic methodology to automatically generate code-representative microbenchmarks that can be used to drive the TDP estimation

Quantum Fluctuations, Decoherence of the Mean Field, and Structure Formation in the Early Universe

We examine from first principles one of the basic assumptions of modern quantum theories of structure formation in the early universe, i.e., the conditions upon which fluctuations of a quantum field may transmute into classical stochastic perturbations, which grew into galaxies. Our earlier works have discussed the quantum origin of noise in stochastic inflation and quantum fluctuations as measured by particle creation in semiclassical gravity. Here we focus on decoherence and the relation of quantum and classical fluctuations. Instead of using the rather ad hoc splitting of a quantum field into long and short wavelength parts, the latter providing the noise which decoheres the former, we treat a nonlinear theory and examine the decoherence of a quantum mean field by its own quantum fluctuations, or that of other fields it interacts with. This is an example of `dynamical decoherence' where an effective open quantum system decoheres through its own dynamics. The model we use to discuss fluctuation generation has the inflation field coupled to the graviton field. We show that when the quantum to classical transition is properly treated, with due consideration of the relation of decoherence, noise, fluctuation and dissipation, the amplitude of density contrast predicted falls in the acceptable range without requiring a fine tuning of the coupling constant of the inflation field ($\lambda$). The conventional treatment which requires an unnaturally small $\lambda \approx 10^{-12}$ stems from a basic flaw in naively identifying classical perturbations with quantum fluctuations.Comment: 35 pages, latex, 0 figure

Electronic/electric technology benefits study

The benefits and payoffs of advanced electronic/electric technologies were investigated for three types of aircraft. The technologies, evaluated in each of the three airplanes, included advanced flight controls, advanced secondary power, advanced avionic complements, new cockpit displays, and advanced air traffic control techniques. For the advanced flight controls, the near term considered relaxed static stability (RSS) with mechanical backup. The far term considered an advanced fly by wire system for a longitudinally unstable airplane. In the case of the secondary power systems, trades were made in two steps: in the near term, engine bleed was eliminated; in the far term bleed air, air plus hydraulics were eliminated. Using three commercial aircraft, in the 150, 350, and 700 passenger range, the technology value and pay-offs were quantified, with emphasis on the fiscal benefits. Weight reductions deriving from fuel saving and other system improvements were identified and the weight savings were cycled for their impact on TOGW (takeoff gross weight) and upon the performance of the airframes/engines. Maintenance, reliability, and logistic support were the other criteria