Estimating 2-D vector velocities using multidimensional spectrum analysis

Wilson (1991) presented an ultrasonic wideband estimator for axial blood flow velocity estimation through the use of the 2-D Fourier transform. It was shown how a single velocity component was concentrated along a line in the 2-D Fourier space, where the slope was given by the axial velocity. Later, it was shown that this approach could also be used for finding the lateral velocity component by also including a lateral sampling. A single velocity component would then be concentrated along a plane in the 3-D Fourier space, tilted according to the 2 velocity components. This paper presents 2 new velocity estimators for finding both the axial and lateral velocity components. The estimators essentially search for the plane in the 3- D Fourier space, where the integrated power spectrum is largest. The first uses the 3-D Fourier transform to find the power spectrum, while the second uses a minimum variance approach. Based on this plane, the axial and lateral velocity components are estimated. Several phantom measurements, for flow-to-depth angles of 60, 75, and 90 degrees, were performed. Multiple parallel lines were beamformed simultaneously, and 2 different receive apodization schemes were tried. The 2 estimators were then applied to the data. The axial velocity component was estimated with an average standard deviation below 2.8% of the peak velocity, while the average standard deviation of the lateral velocity estimates was between 2.0% and 16.4%. The 2 estimators were also tested on in vivo data from a transverse scan of the common carotid artery, showing the potential of the vector velocity estimation method under in vivo conditions.     

Mobile home automation: merging mobile value added services and home automation technologies

In this paper we study mobile home automation, a field that emerges from an integration of mobile application platforms and home automation technologies. We motivate our research and provide a conceptual introduction, which illustrates the need for such applications by a two-dimensional conceptual model of mobility. As a first steps towards a solution we take the user’s perspective and discuss different options of how he might access a mobile home automation service and the controlled devices. Subsequently, we suggest a general system architecture for mobile home automation services and discuss related design decision. This design has been implemented in a research prototype, which we named Remotile. This helps us to discuss typical components, such as modules that integrate various home automation devices. A previous version of this paper was presented at the Sixth International Conference on Mobile Business, 2007. “Andreas Rosendahl, J. Felix Hampe, and Goetz Botterweck, Mobile Home Automation, Merging Mobile Value Added Services and Home Automation Technologies, Proceedings, Sixth International Conference on Mobile Business, 8–11 July 2007, IEEE Computer Society, ISBN 0-7695-2803-1”.     

Continuous-time interface for a micromachined capacitive accelerometer with NEA of 4 g and bandwidth of 300 Hz

A continuous-time accelerometer interface is feasible when a high dynamic range together with a wide signal band is required. In this paper the implementation of a continuous-time force-feedback loop for a capacitive sensor element with a full-scale signal of ±1.5 g is presented. The interface is measured to attain a noise equivalent acceleration (NEA) density of 500  at 30 Hz for the on-chip digitized output and 300  at 30 Hz for the analog output using a capacitive half-bridge sensor element with a single pair of electrodes. The essential circuit structures of the closed-loop sensor will be presented and analyzed in detail.     

Performance and energy impact of parallelization and vectorization techniques in modern microprocessors

While Moore’s law states that the number of transistors is approximately doubled every 2 years, powering these transistors simultaneously is only possible as long as Dennard scaling continues. Unfortunately, voltage scaling has slowed down in recent years, and microprocessor designers have hit what is known as the “utilization wall” or the “dark silicon” effect. Vectorization, parallelization, specialization and heterogeneity are the key approaches to deal with this utilization wall. However, how software developers can maximize energy efficiency of these architectures remains an open question. This paper presents an energy evaluation of parallelization using both physical and logical cores (i.e., SMT/Hyper-Threading), vectorization (SSE, Advanced Vector Extensions and NEON) and dynamic core reconfiguration [ \(\hbox {Intel}^{\circledR }\) ’s Turbo Boost Technology (TBT)]. The evaluation spans microprocessors for embedded, laptop, desktop and server markets, since there is a convergence among them towards energy efficiency. The analyzed processors include Intel’s Core \(^\mathrm{TM}\) i5 and i7 family and ARM \(^{\circledR }\) ’s Cortex \(^\mathrm{TM}\) A9 and A15. Results show that software developers should prioritize vectorization over thread parallelism when possible, as it yields better energy efficiency, especially on the Intel platforms. Application scalability can be reduced drastically when using vectorization and threading simultaneously since vectorization increases pressure on the memory subsystem. Intel’s TBT further improves energy efficiency by an additional 10–20 % depending on the number of active threads.     

Interface and control electronics for a bulk micromachined capacitive gyroscope

An interface and control electronics have been designed and implemented for a bulk micromachined capacitive gyroscope. The system is composed of an application-specific integrated circuit (ASIC) that implements the analog parts of the system and a field-programmable gate array (FPGA) chip that implements the digital signal processing part. Both the system architecture and details of the different circuit blocks will be discussed. The system utilizes phase coherent demodulation to resolve the final output signal. In a typical implementation, phase delay and phase noise in the clock generation cause the signal quality to degrade. A method for correcting these errors will be introduced. A prototype of a microelectromechanical gyroscope has been realized and characterized. The measurement results show that the gyroscope achieves 0.042°/s/  spot noise and 51.6-dB signal-to-noise ratio (SNR) over the 40-Hz bandwidth with a 100°/s input signal.     

Future directions of graphics in entertainment

The author discusses some future directions of computer graphics in entertainment, including: native digital format; digital distribution; Web pages; and coming attractions     

Bayesian network model of overall print quality: Construction and structural optimisation

Prediction of overall visual quality based on instrumental measurements is a challenging task. Despite the several proposed models and methods, there exists a gap between the instrumental measurements of print and human visual assessment of natural images. In this work, a computational model for representing and quantifying the overall visual quality of prints is proposed. The computed overall quality should correspond to the human visual quality perception when viewing the printed images. The proposed model is a Bayesian network which connects the objective instrumental measurements to the subjective opinion distribution of human observers. This relationship can be used to score printed images, and additionally, to computationally study the connections of the attributes. A novel graphical learning approach using an iterative evolve-estimate-simulate loop learning the quality model based on psychometric data and instrumental measurements is suggested. The network structure is optimised by applying evolutionary computation (evolve). The estimation of the Bayesian network parameters is within the evolutionary loop. In this loop, the maximum likelihood approach is used (estimate). The stochastic learning process is guided by priors devised from the psychometric subjective experiments (performance through simulation). The model reveals and represents the explanatory factors between its elements providing insight to the psychophysical phenomenon of how observers perceive visual quality and which measurable entities affect the quality perception. By using true data, the design choices are demonstrated. It is also shown that the best-performing network establishes a clear and intuitively correct structure between the objective measurements and psychometric data.     

A Fixed-Bed Reactor Study of Catalytic Partial Oxidation over Rh/Al2O3: An Indication of a Direct Pathway to CO

Catalytic partial oxidation (CPO) of CH₄ in air was investigated over Rh/Al₂O₃ catalysts (0.01, 0.05, 0.1 and 1 wt% Rh⁰) in co-feed modus in laboratory scale fixed-bed reactors. Main focus was on catalyst stability and selectivity at low temperatures (<700 °C). A particularly high selectivity to CO was observed, indicating existence of a direct pathway.