Percent Of Full Scale Research Articles

Potential regenerative rehabilitation technology: implications of mechanical stimuli to tissue health.

BackgroundMechanical loads induced through muscle contraction, vibration, or compressive forces are thought to modulate tissue plasticity. With the emergence of regenerative medicine, there is a need to understand the optimal mechanical environment (vibration, load, or muscle force) that promotes cellular health. To our knowledge no mechanical system has been proposed to deliver these isolated mechanical stimuli in human tissue. We present the design, performance, and utilization of a new technology that may be used to study localized mechanical stimuli on human tissues. A servo-controlled vibration and limb loading system were developed and integrated into a single instrument to deliver vibration, compression, or muscle contractile loads to a single limb (tibia) in humans. The accuracy, repeatability, transmissibility, and safety of the mechanical delivery system were evaluated on eight individuals with spinal cord injury (SCI).FindingsThe limb loading system was linear, repeatable, and accurate to less than 5, 1, and 1 percent of full scale, respectively, and transmissibility was excellent. The between session tests on individuals with spinal cord injury (SCI) showed high intra-class correlations (>0.9).ConclusionsAll tests supported that therapeutic loads can be delivered to a lower limb (tibia) in a safe, accurate, and measureable manner. Future collaborations between engineers and cellular physiologists will be important as research programs strive to determine the optimal mechanical environment for developing cells and tissues in humans.

Advances in inductive position sensor technology

PurposeThe purpose of this paper is to outline the basic principles of inductive position sensors.Design/methodology/approachThe paper explains one company's advances in inductive position technology in detail, together with some of the applications for which they are now suitable.FindingsIt is shown that concentrating on high volume applications in market sectors such as automotive, user interfaces, and utility metering, where the low cost of these sensors and their moderate accuracy (typically<1 percent of full scale) offers an attractive price/performance ratio.Originality/valueAn original and useful contribution direct from an international technology consulting, product development, and intellectual property [IP] licensing organisation with a reputation for successfully commercialising emerging science and technology. Which, for more than a decade, has made innovations in inductive position sensors and developed application‐specific sensor systems.

Response linearization of a diode detector type radio frequency electric field probe

An EPROM-based linearization circuit with a resolution of 0.1 percent of full scale has been designed to linearize the response of an orthogonal dipole electric field probe terminated with diodes. Design approach, performance, and probe characteristics are discussed. The nonlinear transducer response is first modeled with a fourth-order polynomial which fits the log-transformed calibration data. The equation is then evaluated at discrete points determined by the memory size and the A/D converter resolution. The antilog of the dependent variable is loaded into an EPROM memory for subsequent readout with a D/A converter and summing network. The response of other nonlinear transducers can be linearized by this method.

Measurement of Position for the Centroid of a Plane Figure Using a Video Camera

This paper describes a method of position measurement. The instrument operates on the principle that the center of gravity of an object is, as in balancing a rod, the null point when it is brought to balance. In the equipment a figure of interest is contrasted against the background image by a video camera. The resulting video signal is processed in the instrument to derive voltages representing the xy coordinates of the centroid of the figure. These measurements can be made with an accuracy of ±0.2 percent of full scale for the selected range and a response time of 33 ms.

Precision Capacitor Ratio Measurement Technique for Integrated Circuit Capacitor Arrays

The recent development of integrated circuit capacitor arrays and the growth of their applications have resulted in a need to perform precision testing as an aid to future design improvements. For reasons discussed in this paper, laboratory instruments such as capacitance bridges are not well-suited to this need. In order to test capacitor arrays accurately, a novel technique has been developed. It is based on a special algorithm in which the capacitor array is used as a precision voltage divider. A capacitor array tester consisting of both hardware and software has been built which executes this algorithm. This system has been used to perform measurements upon a large number (thousands) of NMOS and CMOS capacitor arrays. The standard deviation of this tester's measurement error is approximately 0.0009 percent of full scale (0.0088 LSB referenced to 10 bits). In contrast with manual testing with a capacitance bridge (requiring 10 min per array), the tester requires less than 5 s to fully test an array, mark the circuit and move to the next die position.

A new single-chip C/sup 2/MOS A/D converter for microprocessor systems-Penta-Phase Integrating C/sup 2/MOS A/D converter

A new unique conversion technique named the `Penta-Phase Integration' method, applied to a single-chip C/SUP 2/MOS 12-bit analog-to-digital converter designed for microprocessor system, is introduced and described. The newly developed device, fabricated with a standard metal gate CMOS process including an 8-channel multiplexer and TTL compatibility, has several features: unipolar- and ratiometric-conversion can be performed; conversion accuracy within /spl plusmn/0.05 percent of full scale over the -35/spl deg/C-+85/spl deg/C temperature range can be obtained; conversion time is 1.1 ms at a 20 MHz clock frequency, and the device can be operated with a single 5 V power supply and 6 mW power consumption at a 4 MHz clock frequency. The new technique essentially incorporated several methods which divide one conversion cycle into five-phases, accomplish minimization of the error caused by comparator response delay, provide several narrow flat phases to eliminate switching errors due to parasitic capacitance, and enable high clock frequency operation in digital circuits by utilizing C/SUP 2/MOS circuit technology and a synchronized configuration for counters.

The nuclear magnetic resonance magnetometer type 9298

The nuclear magnetic resonance (NMR) magnetometer described here measured homogeneous magnetic fields at a ppm level precision. It offers automatic frequency tracking and digital read-out of the measured magnetic field strength, and is easier to use and much cheaper than existing commercial instruments of similar versatility. It consists of a dual-width NIM plug-in, a probe amplifier box and various probes. Fields between 1 kG and 21 kG can be measured with four proton probes, and two deuteron probes are used from 20 kG to 68 kG. The corresponding six field ranges overlap comfortably. The search and frequency tracking range is a few percent of full scale; the coarse adjustment of the frequency has to be done manually.

A Digital Recording System for Measuring Root Area and Dimensions of Tree Seedlings

ABSTRACT A digital system for rapid measurement and record-ing of the height, stem diameter, root mass area index, and sample number of tree seedlings is described. A linear, solid-state, image sensing scanner with a mechanical transport is used for measuring area while potentiometric transducers are used for measuring height and diameter. The area measurement resolu-tion is better than a 0.3 by 0.5 mm element in a total measurement region of 20 by 27 cm. The accuracies of the length and diameter measurements are within 0.3 percent and 0.5 percent of full scale, respectively. The measurements are displayed digitally and recorded on a teleprinter in a computer-compatible format.

An RC Logarithmic Converter-Digitizer

Theoretical considerations and experimental data support the suggestion that high accuracy of conversion and long-term stability could be obtained with a logarithmic RC converter-digitizer. The operation of the proposed converter is based on time measurements of the exponential voltage decay across a linear RC network. Linearity error of this converter, built with commonly available and noncritical components, was found to be less than 0.05 percent of full scale for a two-decade operation.

Development and Successful Testing of a Continuous-Wave, Logging-While-Drilling Telemetry System

Patton, B.J., SPE AIME, Mobil Research and Patton, B.J., SPE AIME, Mobil Research and Development Corp. Gravley, W., SPE-AIME, Mobil Research and Development Corp. Godbey, J.K., SPE-AIME, Mobil Research and Development Corp. Sexton, J.H., Mobil Research and Development Corp. Hawk, D.E., Mobil Research and Development Corp. Slover, V.R., Mobil Research and Development Corp. Harrell, J.W., Mobil Research and Development Corp. A logging-while-drilling telemetry system, using a digitally encoded, phase-modulated, continuous-pressure-wave signal in the mud inside the phase-modulated, continuous-pressure-wave signal in the mud inside the drillstring, was tested successfully. In addition to transmission capability, the tests provided information to confirm signal attenuation and depth-range theory. Introduction Mobil Research and Development Corp.'s development of a logging-while-drilling (LWD) telemetry system for sending information from down hole to the surface was concluded with a series of successful field tests during 1971. The field tests were a direct result of many years of exploratory research and 4 years of intensive research and development. This paper describes the development and field testing of a prototype system equipped to transmit 15 channels of information, and one channel for frame synchronization. Most of the information transmitted was related to internal conditions of the down-hole system and was used for operational diagnostics. System diagnostics included internal temperatures and voltages, mud turbine speed, motor slip (torque), a measure of the transmitter coherence, and alternator field current. Other than down-hole mud temperature and tool vibration, the system did not include measurement of conventional logging parameters such as hole direction and inclination, formation properties, drilling variables, and bottom-hole conditions. A later generation of the system that includes those measurements is now being field tested by a major service company. A successful telemetry system for use while drilling will satisfy a long-standing industry need. As early as the 1930's, attempts were being made to solve the many problems involved. Recent reviews list the many problems involved. Recent reviews list the many publications and patents issued during the last 40 years and publications and patents issued during the last 40 years and discuss the principal telemetry methods and the developers involved. Information obtained from down hole while drilling, generally can be placed in two categories: drilling variable or hole information, and formation characteristics. Included in the former might be hole direction and inclination, tool-face heading, weight and torque at the bit, temperature, mud properties, tool vibration and acceleration. Formation logs might include resistivity, natural gamma ray, etc. Data rate specification is critical in this system and is a trade-off between more logs, higher accuracy, and depth range. We concluded that a good compromise would be to specify the minimum data rate necessary to transmit five logs with a data point each foot of depth and with an accuracy of 0.1 percent of full scale (10 data bits plus two bits overhead). This leads to a requirement of 60 bits/ft. The data rate in bits per second required by this specification is ...................(1) JPT p. 1215

Four-quadrant JFET multipliers

A novel four-quadrant /spl plusmn/1 V input, /spl plusmn/1 V output JFET analog multiplier cell is described in this work. The cell consists of one low-power operational amplifier, one commercially available dual JFET pair, three seven-resistor thin-film resistor packages, and one other trim resistor. An amplifier input offset voltage adjust and a trim resistor adjust are sufficient to yield /spl plusmn/0.5 percent of full-scale accuracy at a single temperature. The addition of a second temperature-compensated low-power amplifier results in a high input impedance multiplier with an overall accuracy of /spl plusmn/3 percent of full scale in the temperature range from 0 to 50/spl deg/C. The complete unit has a no-signal power dissipation of 0.3 mW, a full-signal power dissipation of 4 mW, and a half-power frequency response of about 10 kHz.

A Digital Force Transducer

A digital force transducer design, more specifically defined as an indirect digital device, is described. This device retains most of the advantages of analog force transducers and incorporates the stability and computer compatibility of digital systems. The digital force transducer is capable of handling forces of up to 700 g, with the sensor currently used, at an 8-bit resolution of 4 g. The interrogate rate is 7 kHz, permitting identification of force frequencies of well over I kHz. The linearity is better than ±0.1 percent±one-half of the least significant bit (LSB), the repeatability is better than ±0.25 percent of full scale. The device design described has been highly reliable over a three-year period seeing almost daily use. The transducer is used as an integral part of an all-digital tensile tester where its performance exceeds that required by the test system. The transducer is economical to design and build when compared to analog transducers coupled to commercial analog-to-digital (A-D) hardware.

A System for Locating Points, Lines, and Planes in Space

A microprocessor-based system for locating points, lines and planes within a cubic space 50 cm on a side is described and its performance evaluated. The technique is based on measuring the transit times of a shock wave produced by a small electric spark to each of 3 linear orthogonal microphones. Arranging 3 spark gaps in a plane permits the determination of the orientation of lines and planes in space. A technique is described to compensate for air temperature variations which have a direct effect on system repeatability. The effect of random room air currents has been studied. The linearity of the system was measured and found to contain an error of ±0.12 percent of full scale. Overall worst case (99.73-percent confidence interval) system accuracy was found to be 0.08 ± 0.96 mm.

A Digital Feedback Integrator for Precision Photocurrent Measurements at High Data Rates

A digital feedback circuit has been developed that integrates the current from a photomultiplier tube or other current source and delivers a digital output signal. The high conversion rate permits precise integration of the photocurrent resulting from chopped or pulsed-light sources. The processing lag of approximately 300 ns makes this a real-time system for most applications in that it delivers discrete pulse-by-pulse readouts for signals spaced at this or longer intervals. The measurement of pulse area represents optimum processing in photo-limited situations. The circuitry is based upon the delta-modulation encoder with the refinement that return-to-zero (RZ) pulses are used to eliminate nonlinearities due to contiguous-pulse effects. With the component values shown, the circuit area-encodes pulses of 7-?A peak amplitude with a maximum nonlinearity of about 0.1 percent of full scale. The feedback error of the circuit produces a random noise component that varies inversely with the square-root of pulse duration and is about 0.1 percent of full scale, peak-to-peak, for pulses of 10-ms duration.

The Assessment of Emission Analysis Accuracy

An assessment of the accuracy of emission measurements is fundamental to an understanding of the ability of an organization to comply with emission regulations. Without a knowledge of the measurement accuracy, the significance of observed differences cannot be assessed. In addition, the average emission level that a group of engines must achieve for compliance is a function of the accuracy of the measurement of the exhaust constituents; i.e., the less accurate the measurement, the lower the average level must be to assure that essentially all engines pass the compliance tests. The accuracy assessment specifically included: 1) test instrument precision, 2) calibration gas accuracy and 3) sample error due to the distribution of data resulting from gas concentrations that are spatially non-uniform. In addition, the accuracy assessment required the consideration of the following general topics: the propagation of errors in a calibration hierarchy, the proper choice of error units, surveys of instrument precision, the evaluation of the significance of various instrument errors, the assessment of the significance of sampling error, and the consideration of methods for demonstrating representative samples and improving instrument precision. An accuracy assessment considering those factors resulted in the following conclusions: 1) Emission instrument precision is best expressed as percent of full scale. 2) The proper units for bias errors are percent of point. 3) Calibration-to-calibration repeatability may be utilized to estimate instrument precision. 4) Instrument precision shows wide variations from day to day. 5) Correcting past data by post-test calibration adjustments will not, in general, improve emission data altered by instrument drift. 6) Sampling error due to the distribution of emission concentrations in space is the single largest source of uncertainty in gas turbine emission measurements.

A new technique of thermal RMS measurement

A thermal technique of rms measurement is described which uses the base-emitter junction of a bipolar transistor to sense the temperature change of a monolithic chip due to the power dissipation of a companion diffused resistor. An analysis is presented which provides: 1) design equations for performing error compensation to minimize the nonlinearity of the rms-to-dc conversion, and 2) ac feedback network design to optimize the low frequency cutoff and settling time product. Resulting rms converters had midband accuracies of /spl plusmn/0.05 percent of full scale over a dynamic range of 30 dB, high frequency limits of 100 MHz for 2 percent accuracy, and settling times less than 1 s.

A Phantom Burden for Current Transformer Calibration

A technique is presented for applying a burden to a current transf ormer being calibrated in which the power and reactive volt-amperes are returned to the supply rather than being absorbed in a passive network. The transfer is accomplished either by the magnetic shield if a compensated current comparator is used as the ratio standard, or by an auxiliary current transformer in circuits which employ other standards. Electronic circuitry provides the necessary volt-amperes for exciting the magnetic shield of the current comparator or the auxiliary current transformer, and the current transformer being calibrated, to produce the desired power transfer. The circuit requirements are analyzed and equipment which can develop burdens with both in-phase and quadrature components up to 10 ohms, at secondary currents up to 10 amperes, and for a 0.6 percent accuracy class current transformer or better, is described. The burden setting, which is independent of current, may be made by in-phase and quadrature dials to an accuracy of about one percent of full scale.

Delta modulation in DVM design

Existing digital voltmeters (DVM) do not sell as well as analog types having parallel capabilities for the simple reason that they cost more. Though the DVM has the superior performance to compete in the popular class of instruments, it must sell for less than 100 dollars. This means new thinking and radical alteration in present designs. New thinking developed the delta modulation DVM discussed here; it has high performance and is economical. Performance figures include an input impedance of >100 M/spl Omega/, an accuracy typically 0.3 percent of full scale, and a noise rejection figure of >60 dB at main frequencies >49 Hz. Power consumption is about 600 mW.

Magnetoresistance Multiplier for the Accurate Measurement of Power in the Audio Frequency Range

The application of a commercially available component (Misto-R multiplier by American Aerospace Conntrols Inc.) to accurate power measurement over the audio frequenncy range is investigated. It is shown that the errors inherent to the magnetoresistive component can be considerably reduced by appropriate electronic circuitry. Two circuits were constructed and tested: a dc circuit and an ac circuit. The accuracy of the dc multiplier is better than 0.05 percent of full scale. The accuracy of the ac multiplier at a power factor of 1.0 is better than 0.1 percent of full scale up to a frequency of 4000 Hz and approaches 0.5 percent at 10 kHz. Expressions for static and dynamic errors are given and it is shown that the static errors are small with respect to the dynamic errors. It is believed that further broadening of the frequency and power factor ranges for the specified accuracy of 0.1 percent can be achieved by modifying the structure of the bridge and adopting suitable circuitry.

An Electronic Self-Balancing Instrument Transformer Testing Device

A self-balancing instrument transformer testing device is described by which the voltage and current errors and phase displacements of instrument transformers can be read off or recorded directly with a printer or digital instrument. The circuitry correr sponds to the usual difference circuit in which the test transforme- is compared with a standard transformer. The voltage difference between the secondary voltages of the test and the standard transformer is balanced by a voltage that is separated into two components, one being in phase with the voltage of the standard transformer (reference voltage) and the other in quadrature. The direct voltages with which the reference voltages are multiplied to generate the balancing voltage are a measure of the errors and the phase displacements of the instrument transformers. The circuits generating the reference voltages, the zero voltage amplifier, the phase-selective rectifier, and the multiplier circuit are described. The device is designed for measuring the errors of current transformers between 1 and 200 percent of rated current and the errors of voltage transformers between 40 and 120 percent of the rated voltage, to an accuracy of about 1 percent of full scale. It may also be used to measure the impedance of resistors, inductors, and capacitors.