Describes Design Considerations Research Articles

Practical Considerations for a Digital Inductive-Switching DC/DC Converter With Direct Battery Connect in Deep Sub-Micron CMOS

This paper describes design considerations for a digital inductive-switching DC/DC converter suitable for direct battery connection in a deep sub-micron CMOS process. Digital control techniques and robust circuit design methods take advantage of the advanced process technology while avoiding the barriers to direct battery connection and high efficiency, high power density voltage conversion. The approach is verified on a prototype converter, implemented in 40 nm standard bulk CMOS. The design achieves a peak efficiency of 95% for an input range of up to 5.5 V. The transient response is optimized for typical mobile SoC operating conditions and achieves step response times as fast as 35 μs/V under load.

Novel strategies in tendon and ligament tissue engineering: Advanced biomaterials and regeneration motifs.

Tendon and ligaments have poor healing capacity and when injured often require surgical intervention. Tissue replacement via autografts and allografts are non-ideal strategies that can lead to future problems. As an alternative, scaffold-based tissue engineering strategies are being pursued. In this review, we describe design considerations and major recent advancements of scaffolds for tendon/ligament engineering. Specifically, we outline native tendon/ligament characteristics critical for design parameters and outcome measures, and introduce synthetic and naturally-derived biomaterials used in tendon/ligament scaffolds. We will describe applications of these biomaterials in advanced tendon/ligament engineering strategies including the utility of scaffold functionalization, cyclic strain, growth factors, and interface considerations. The goal of this review is to compile and interpret the important findings of recent tendon/ligament engineering research in an effort towards the advancement of regenerative strategies.

Experimental Investigation of Pattern Layout Effect on Radio-Frequency Performance of Thin-Film Silicon-on-Insulator Power Metal–Oxide–Semiconductor Field-Effect Transistors

This paper describes design considerations for the thin-film silicon-on-insulator power metal–oxide–semiconductor field-effect transistors for linear-amplification applications. The linear-amplification characteristics and DC performance depend on the grand interconnection pattern. We prefer to put the grand pattern on the drain (output) side. There are optimum finger lengths that provide the best linear amplification characteristics. The finger length also depends on the operating frequency and total gate width.

Skin Impedance Measurements for Acupuncture Research: Development of a Continuous Recording System

Skin impedance at acupuncture points (APs) has been used as a diagnostic/therapeutic aid for more than 50 years. Currently, researchers are evaluating the electrophysiologic properties of APs as a possible means of understanding acupuncture's mechanism. To comprehensively assess the diagnostic, therapeutic and mechanistic implications of acupuncture point skin impedance, a device capable of reliably recording impedances from 100 kΩ to 50 MΩ at multiple APs over extended time periods is needed. This article describes design considerations, development and testing of a single channel skin impedance system (hardware, control software and customized electrodes). The system was tested for accuracy against known resistors and capacitors. Two electrodes (the AMI and the ORI) were compared for reliability of recording over 30 min. Two APs (LU 9 and PC 6) and a nearby non-AP site were measured simultaneously in four individuals for 60 min. Our measurement system performed accurately (within 5%) against known resistors (580 kΩ–10 MΩ) and capacitors (10 nF–150 nF). Both the AMI electrode and the modified ORI electrode recorded skin impedance reliably on the volar surface of the forearm (r = 0.87 and r = 0.79, respectively). In four of four volunteers tested, skin impedance at LU 9 was less than at the nearby non-AP site. In three of four volunteers skin impedance was less at PC 6 than at the nearby non-AP site. We conclude that our system is a suitable device upon which we can develop a fully automated multi-channel device capable of recording skin impedance at multiple APs simultaneously over 24 h.

Design considerations and implementation of a DSP-based car-radio IF Processor

This paper describes design considerations and the implementation of a software defined radio receiver encompassing intermediate frequency (IF) digitization. The proposed system-on-chip performs the demodulation of both AM and FM stereo signals, digitized at the IF by means of a high dynamic range sigma-delta bandpass A/D converter. The chosen architecture combines hardware and software functions, trading flexible programmability with area occupancy. The software includes also true blind equalization of the FM signals, resulting in the rejection of the neighbor channels and of any other interfering signal, even under severe multipath conditions. The described chip, realized in a 0.18-/spl mu/m CMOS technology, occupies an area of 15.2 mm/sup 2/ and is enclosed in a 64-pin package.

Natural Killer Cell Cytotoxicity: A Methods Analysis of Versus Flow Cytometry Chromium Release

The purpose of this study is to describe design considerations for the use of flow cytometry (FC) compared to 51chromium (51Cr)-release assays utilizing cryopreserved peripheral blood mononuclear cells (PBMCs) to detect natural killer (NK) cell cytotoxicity. Subjects were 10 healthy women aged 18 to 39 years. Intra-assay variability between methods differed only at the lowest effector-target ratios evaluated. Interassay variability was wide but did not differ between methods. The relationship of lytic unit-10 between methods was strongly positive. Cytotoxicity detected by 51Cr release was higher than that detected by FC for all 10 subjects. Cost was comparable. However, had more assays been performed, technician time would have been greater with flow cytometry. More whole blood was needed to perform the flow cytometry cytotoxicity assay than 51Cr-release cytotoxicity assay. The authors found no compelling reason to adopt NK cell cytotoxicity by flow cytometry over 51Cr release.

Robotic stroke therapy assistant

The Rehabilitation Technologies Division of Applied Resources Corp. (RTD-ARC) has engaged in a Phase I effort to commercialize a robotic bi-manual therapy machine for use in stroke rehabilitation, in cooperation with the VA Rehabilitation R&D Center in Palo Alto. The robotic therapy device, called ARCMIME here in order to differentiate it from its clinical predecessor, has the potential to improve rehabilitation outcomes significantly for individuals who have upper limb impairments due to stroke and other brain injuries.This paper describes design considerations and clinical outcomes with regards to the Phase I system. It was found that the kinematically simpler system adequately replicated the data outcomes of the more sophisticated PUMA-based experimental test rig.

Tritium Processing and Tritium Laboratory in the International Fusion Materials Irradiation Facility (IFMIF)

ABSTRACTThis paper describes design considerations on the tritium processing and the tritium laboratory in the International Fusion Materials Irradiation Facility (IFMIF) that is being developed for neutron irradiation testing of candidate fusion materials. In the IFMIF the tritium is generated by various reactions. However, the irradiated materials will have high activities. The tritium processing method is designed on the basis of the evaluation for tritium source and generation rate. The tritium laboratory for post irradiation examination (PIE) of the activated/tritium contaminated materials is evaluated.

Design considerations and verification testing of an SEE-hardened quad comparator

Describes design considerations and single-event effect (SEE) testing results of a hardened quad comparator equivalent to the industry standard "139" device. The hardened part uses redundancy and hardened complementary BiCMOS processing to achieve improved SEE performance.

Smartfire: an Intelligent Cfd Based Fire Model

This paper describes a project aimed at making Computational Fluid Dynamics (CFD)- based fire simulation accessible to members of the fire safety engineering community. Over the past few years, the practice of CFD-based fire simulation has begun the transition from the confines of the research laboratory to the desk of the fire safety engineer. To a certain extent, this move has been driven by the demands of performance based building codes. However, while CFD modeling has many benefits over other forms of fire simulation, it requires a great deal of expertise on the user’s part to obtain reasonable simulation results. The project described in this paper, SMARTFIRE, aims to relieve some of this dependence on expertise so that users are less concerned with the details of CFD analysis and can concentrate on results. This aim is achieved by the use of an expert system component as part of the software suite which takes some of the expertise burden away from the user. SMARTFIRE also makes use of the latest developments in CFD technology in order to make the CFD analysis more efficient. This paper describes design considerations of the SMARTFIRE software, emphasizing its open architecture, CFD engine and knowledge-based systems.

An electrically isolated balanced wideband current source: basic considerations and design.

At relatively high frequencies, the application of an alternating current through the body or a body segment results in electromagnetic stray fields which reduce the amount of current actually injected into the tissue under study. This radiation effect can be reduced by use of a symmetrical configuration current source. The symmetry of such an arrangement, however, depends on the stray capacitances of the source with respect to surrounding equipment. To minimise these effects, it is required that the source is electrically isolated from the surrounding equipment and the subject under study. In this manner stray capacitances with respect to elements of the current source are reduced. In such a configuration common mode voltages to the input amplifier of the measuring system are also reduced. The paper describes design considerations and the implementation of a wideband current source capable of injecting alternating current in the order of 300 microARMS into biological tissue having impedances up to 1 k omega. Current stabilisation is obtained by means of a control circuit which measures the actual current passing through the tissue under study. Leakage currents arising from shielding and stray capacitances are compensated for. The usable frequency range is between 4 kHz and 1024 kHz and current stability is better than 0.2%. Through the use of a symmetrical, floating circuit a configuration is obtained which substantially reduces stray effects. The current source is connected to other circuits by means of two isolation ports: (1) a transformer coupling for the carrier frequency; and (2) an opto-coupler to transfer a phase reference signal obtained from current measurement. The current amplitude can be modulated by controlling the reference input to the control loop by means of a third auxiliary isolation port for transfer of the modulating signal.

Cognitive Research, Learning Theory, & Software Design: The Virtual Library

The idea that theory and research on learning and cognition could influence the way we teach and structure learning environments has established a new paradigm for software designers [1]. According to a social-constructivist perspective, discourse, authentic tasks, exploratory and student-centered learning are integral to learning and understanding. The purpose of this article is to describe design considerations that were made for a software prototype called the Virtual Library—considerations that were framed by cognitive research and learning theory. When completed, the software will assist preservice teachers in learning about educational psychology and instructional design. The software resembles a library where students browse through a series of 3-D, virtual buildings to understand research, theory, and classroom applications of educational psychology and instructional design. Students have access to movies, text, images, and World Wide Web sites. They also have opportunities to participate in interactive lessons and e-mail conversations with other students, classroom teachers, educational psychologists, and instructional designers.

Pan-browser support for annotations and other meta-information on the World Wide Web

This paper describes an innovative approach for groups to create and share commentary about the content of documents accessible via the World Wide Web. In particular, the system described supports the creation, presentation, and control of user-created meta-information, which is displayed with the corresponding documents but stored separately from them. The typical use for this mechanism is to support annotations about documents accessed through browsing clients of the Web. In contrast to other approaches, the system described herein does not depend on changes in, or specializations to, Web browsers or servers. Rather, the system takes advantage of the notion of application-specific stream transducers; most of the functionality of the system is provided by a specialized proxy. We describe design considerations, the system architecture, usage scenarios, our initial implementation, and future work.

An oscillator circuit for electrostatically driven silicon-based one-port resonators

This paper describes design considerations and characteristics of oscillator circuitry for electrostatically driven silicon-based one-port resonators, used as resonant strain gauges. The oscillation conditions for a general, single transconductance oscillator are theoretically derived. In order to start oscillation, guidelines to select proper bias conditions for the resonator are presented, taking the non-linear effects into account. An oscillator circuit has been designed in CMOS technology in order to verify the theory experimentally. Experimental results of the oscillator in combination with a silicon beam resonator are given.

Laboratory Evaluation of Prophylactic Knee Brace Performance Under Dynamic Valgus Loading Using a Surrogate Leg Model

Because of contradictory data accumulating from on-field trials of prophylactic knee braces, benchtop laboratory studies of brace performance have become important. This study (1) describes design considerations for a mechanical leg surrogate developed for prophylactic brace testing, (2) validates surrogate performance under dynamic lateral loading, and (3) reports comparative performance data for eight commercial knee braces tested using this surrogate system.

On the possibility of observing quantum reflection in the scattering of atoms from a nearly resonant light wave

We describe design considerations for an experiments on the scattering of optically cooled atoms from a standing wave light field. We discuss importance of atom-field interaction times and standing wave intensities in the context of an experiment which seeks to observe quantum reflection of cold atoms from the pseudo potential which describes the atom-field interaction.

A desktop computer-based workstation for display and analysis of 3- and 4-dimensional biomedical images

While great advances have been made in developing new and better ways to produce medical images, the technology to efficiently display and analyze them has lagged. This paper describes design considerations and development of a workstation based on an IBM PC/AT personal computer for the analysis of three- and four-dimensional medical image data.

Control Design of an Antenna Pointing Control System with Large On-Board Reflectors

This paper describes design considerations for the antenna pointing control system in ETS-VI. The satellite flexible structures including a 3.5-m main-reflector, a sub-reflector with an antenna pointing mechanism, and large solar paddles were modelled mathematically.The interactions between the satellite main body and antenna reflectors were estimated, and the structural model for application to control design was modified based on the results. By analizing the sensitivities of the control system parameters, it was clarified that the gain change of the control loop must be increased by about 3.6 dB taking the structural parameter variations into consideration.

The Cathedral Square substation anchored excavation, Vancouver, British Columbia

The paper describes the design of and construction experiences at a 20 m deep vertical excavation that was required in the heavily built-up downtown Vancouver area. The subsurface conditions may be generalized as an upper 3 m of sand and gravel followed by a sandstone sequence from fine to coarse with increasing depth. Depending on grain size and cementation, the compressive strength of sandstone varied from 6 to 30 MPa.The excavation support system consisted of soldier piles and posttensioned anchors in the overburden and posttensioned anchors and shotcrete in the rock face. Drainage control was provided by a system of deep, vertical perimeter drains connected to a number of near-horizontal drains in the rock face.The paper describes design considerations for the excavation, including an estimate of seismic-induced deformations. The construction aspects described include the use of a rapid cure method to predict grout strength, the use of couplers in anchor bars, and anchor load tests. During construction, a number of failures, attributed to stress corrosion, occurred in high tensile strength steel anchors. The details of the investigation and testing program used to provide an estimate of remaining anchor life are described. Finally, the paper summarizes results from the field instrumentation. Key words: anchors, construction, corrosion, deformation, drainage, excavation, failure, grout, instrumentation, stress.

A 94-GHz Diode-Based Single Six-Port Reflectometer

This paper describes design considerations and gives measurement results for a single six-port reflectometer constructed from WR-10 waveguide with silicon Schottky diode detectors. Tradeoffs between various types of power detectors are discussed along with criteria for six-port junction design. The merits of two calibration procedures are compared. Measurements at 94 GHz indicate good agreement between expected and experimental values of q-points and of a sliding mismatch with nominal 0.1 reflection coefficient.