Steady-state analysis and design of a switched-capacitor DC-DCconverter

A representative switched-capacitor DC-DC converter topology is presented, circuit operation is explained, and control strategies are identified. State-space averaging is used to analyze steady-state performance and to develop control criteria and design equations. The analytical results are verified by SPICE simulation     

The Freja ultraviolet imager

Auroral images acquired by satellite instrumentation have proven to be a crucial component of the scientific equiry into the physical processes of the Earth's magnetosphere. TheFreja mission provided an opportunity to extend these measurements into the temporal and spatial regime commonly associated with ground-based optical imagers. Employing the basic procedure used successfully in theViking program allowed image repetition rates of 6 s to be achieved with simultaneous exposure of all pixels within the field-of-view. Typical exposure times of 0.3 s required development of an improved image intensifier system and operational requirements resulted in image formats covering approximately one-third of a spin. Simultaneously exposing two broad-band UV cameras, the instrument generates in its normal operational mode 264.6 kbytes per image pair. Results from initial operations confirm the design approach and suggest such imagers can be routinely included on challenging low cost missions such asFreja.     

Implementation of hand geometry: an analysis of user perspectives and system performance

This discusses the implementation issues of installing a commercially available hand geometry system in the current infrastructure of Purdue University's Recreational Sports Center. In addition to a performance analysis of the system, a pre- and post-data collection survey was distributed to the 129 test subjects gathering information on perceptions of biometrics, in particular hand geometry, as well as participants' thoughts and feelings during their interaction with the hand geometry device. The results of the survey suggest that participants were accepting of hand geometry. Additionally, analyses of the participants' survey responses revealed that 93% liked using hand geometry, 98% thought it was easy to use, and 87% preferred it to the existing card-based system, while nobody thought the device invaded their personal privacy. System performance achieved a 3-try match rate of 99.02% (FRR 0.98%) when "gaming"/potential impostor attempts were removed from analysis. The failure to enroll rate was zero. Statistical analyses exposed a significant difference in the scores of attempts made by users with prior hand geometry usage, and subjects that could not straighten out their hand on the device. However, there were no statistical difference in the effects of rings/no rings, improper hand placements/proper hand placements, or gender on hand geometry score.     

Global Response of Martian Plasma Environment to an Interplanetary Structure: From Ena and Plasma Observations at Mars

As a part of the global plasma environment study of Mars and its response to the solar wind, we have analyzed a peculiar case of the subsolar energetic neutral atom (ENA) jet observed on June 7, 2004 by the Neutral Particle Detector (NPD) on board the Mars Express satellite. The “subsolar ENA jet” is generated by the interaction between the solar wind and the Martian exosphere, and is one of the most intense sources of ENA flux observed in the vicinity of Mars. On June 7, 2004 (orbit 485 of Mars Express), the NPD observed a very intense subsolar ENA jet, which then abruptly decreased within ∼10 sec followed by quasi-periodic (∼1 min) flux variations. Simultaneously, the plasma sensors detected a solar wind structure, which was most likely an interplanetary shock surface. The abrupt decrease of the ENA flux and the quasi-periodic flux variations can be understood in the framework of the global response of the Martian plasma obstacle to the interplanetary shock. The generation region of the subsolar ENA jet was pushed towards the planet by the interplanetary shock; and therefore, Mars Express went out of the ENA jet region. Associated global vibrations of the Martian plasma obstacle may have been the cause of the quasi-periodic flux variations of the ENA flux at the spacecraft location.     

Towards a coherent remote sensing data policy

Access to space-based remote sensing data is critical for Earth science and the study of global change. This article summarizes a variety of US government Earth science data policies and problems. The authors examine current efforts to develop data policies for the next generation of US remote sensing programmes, noting likely problems based on past experiences. They argue that the goal of US Earth science data policy should be to provide the widest possible dissemination of data. Setting such a goal permits the development of a simple, coherent data policy that serves scientific, commercial and US government interests.     

Family of constrained signal detectors for hyperspectral imagery

Generalized likelihood ratio tests (GLRTs) are derived for the problem of detecting targets in hyperspectral images. These detectors are derived under the assumptions that the signals from the materials in the image mix linearly and that the noise in the system is Gaussian. It is also assumed that the abundances of the signals from the various materials in a pixel must sum to one. This constraint models the fact that the material abundances in a pixel are just the fraction of the pixel that they occupy. Under these assumptions, detectors are derived which outperform the detectors derived without the sum-to-one constraint.     

Use of combined light flash and plasma measurements to study hypervelocity impact processes

We present new measurements concerning generation of light flash during hypervelocity impacts. We use iron particles (10⁻¹³ to 10⁻¹⁷ kg) with velocities over the range 1 to 42 km/s impacting semi-infinite targets (aluminium and molybdenum). The main results of previous work in the field are found to be reproduced with some slight deviations. For iron projectiles with given mass and velocity the energy of the flash (normalized to mass) is proportional to velocity to the power of 3.5 for aluminium targets and 3.9 for molybdenum targets. The duration of the flash is of order 1 microsecond. Simultaneous measurements of the generation of impact plasma do not change this. The onset of plasma generation of the bulk target material does not affect the total light flash energy. We discuss the duration of the flash compared to a simple calculation of temperature in the target and plasma vs time.     

Nanotechnology-based molecular test equipment (MTE)

This paper describes original research efforts in the design, simulation, and development of nanotechnology-based molecular test equipment (MTE). This is a research effort for testing printed circuit boards independent of traditional automatic test equipment (ATE) through the fabrication of MTE within integrated circuits (ICs). The MTE is embedded within the IC substrate and encapsulated within nanoprobes that connect between the surface and the substrate of the IC at various functional areas. A process is followed whereby IC device simulation is performed to assess the electrical, chemical, and structural properties of integrated and adjacent substrate devices. Through this approach the nominal and failed device performance parameters of interest to substrate-based MTE are found. Discussion of the development and application of MTE within IC architectures is provided, including such topics as the effect of substrate composition on the design and realization of MTE, interfaces between MTE and IC devices, and reporting of MTE results to the IC surface and technician. Potential application areas within different device functions will also be identified. A chemical structure diagram is also provided to illustrate the implementation of MTE using discrete device configurations with MTE-augmented logic