Analog Instruments Research Articles

Digital processing of hot wire anemometer signals in intermittently turbulent flows

Fast data acquisition and digital signal processing techniques with a 16-bit microcomputer are applied to the study of intermittently turbulent flow in the transitional boundary layer. The digital methods compare favourably with traditional analogue instrumentation and the potential for futher detailed processing is extensive. The results have highlighted some structural features of the intermittent transitional boundary layer which are masked when using bulk time-averaged techniques.

A measurement technique for the output power in a drive motor system

The possibility of using ‘observers’ in the output power for a class of drive motor systems is considered in the paper. The idea presented calls for transferring the standard power measurements made by analogue instruments to the A D power converters and computer.

A microcomputer-microprocessor-based DC motor speed controller for undergraduate electric machinery laboratory

A microcomputer-microprocessor-based control system is described for speed control of a 7.5 hp separately excited DC motor in the undergraduate electric machinery laboratory at Montana State University. The system uses a Hewlett-Packard (HP) 3497A data acquisition system and a HP/85B microcomputer in conjunction with a Z80 microprocessor. It is used by students to obtain the characteristic of the motor and control its speed under various load conditions. Increased efficiency has been observed in computerized data collection as compared with the traditional method of data collection using analog instrumentation. The control strategy is such that students at the junior level, with limited background in control theory and electronics, can understand its operation. Some experimental results are presented, laboratory experiences are reported, and student responses are evaluated. Additional experiments for the electrical machinery laboratory are also proposed. >

The selection of resistors for precise analogue instrument circuits: a statistical method

A method involving a computer is described for selecting resistors for precise analogue instrument circuits. A statistical analysis is carried out which provides formulae for calculating the probability of non-duplication of resistors, and also the predicted discrepancy for specified group and batch sizes. Theoretical and actual values are compared: the agreement is such that the theoretical formulae can be used confidently to specify batch sizes to obtain indicated discrepancies for given group sizes. The method is of practical importance in selecting closely matched resistor ratios, and matched resistors, for precise analogue circuits.

Stress analysis with a magnetic anisotropy sensor and its application: 37160 Yamada, H.; Kishimoto, S.; Itoh, M.; Takenaka, Y. 11th World Conference on Nondestructive Testing, Las Vegas, Nevada (United States), 3–8 Nov. 1985. Vol. 1, pp. 607–614. Taylor Publishing Co., Dallas (1985)

This chapter focuses on electrical measuring instruments and measurements. To detect electrical quantities, such as current, voltage, resistance or power, it is necessary to transform an electrical quantity or condition into a visible indication. This is done with the aid of instruments (or meters) that indicate the magnitude of quantities either by the position of a pointer moving over a graduated scale, known as an analog instrument, or in the form of a decimal number, known as a digital instrument. All analog electrical indicating instruments require three essential devices, namely, a deflecting or operating device, a controlling device, and a damping device. There is no difference between the basic instrument used to measure current and voltage as both uses a milli ammeter as their basic part. This is a sensitive instrument that gives FSD for currents of only a few milli amperes. When an ammeter is required to measure currents of larger magnitude, a proportion of the current is diverted through a low value resistance connected in parallel with the meter. Such a diverting resistance is called a shunt.

Experiment on “discovery” STS 51-C: Aggregation of red cells and thrombocytes in heart disease, hyperlipidaemia and other conditions

The aim of this experiment was to study aggregation of red cells in the blood of patients with ischaemic heart disease, diabetes, hyperlipidaemia, and (silent) cancer, and in two normal donors. Reconstituted blood using IgG was also used. The instrument, the automated slit-capillary photo-viscometer (100 kg weight) was set on the middeck of the Space Shuttle. An analogous instrument was at the Kennedy Space Center. Blood was obtained from donors, anticoagulated, and adjusted to haematocrit of 30% using native plasma. Experiments took place at 25°C, during which blood was forced to flow in the slit formed by two parallel glass plates. Macro and microphotography was carried out at specific intervals controlled by a computer. During stasis, lasting 6 minutes, aggregates (or clumps) of the red cells were formed. Results indicated that red cell aggregates do form under zero-G; that such aggregates are smaller than the ones obtained at one-G; that morphology is different, the zero-G showing rouleaux while one-G showing usual sludge-like clumps of red cells in all severe disorders. Platelets appeared to remain monodisperse under zero-G. Assuming that these data can be confirmed, one could suggest that zero-G affects cell-cell interaction, and may consequently influence the internal microstructure of the cell membrane and of the receptors, as well as their activity. Gravitational studies may thus open a new door on immunology and haematology in general.

飯島製錬所におけるコンピュータを利用した改善

Since 1973, the oil crises have deeply influenced to the zinc industry in the world. In order to overcome a rise in energy cost, Iijima electrolytic zinc refinery has carried out various improvements for plant modernization and energy saving. Extensive application of the computer control system to the plant operation is a typical example.In 1984, Fujitsu's super mini-computer (S-3500) was installed, and the “Akita Zinc Refinery Total Information Control System” abbreviated to “ATICS” was developed for the pursuit of more effective operation in the plant and administration in the office. From 1985 to 1987, Yokogawa's digital control stations (CENTUM) were installed to replace the analog instruments in the field control rooms. The combination of the field side digital control stations and the host computer has brought not only the effective reduction in labor and energy cost, but also the significant improvements for stable plant operation.This paper presents a summary of the Factory Automation System and the Office Automation System at Iijima Zinc Refinery, including the effectiveness of the several automatic process controls as an example.

Data acquisition system for chemical kineticstudies

A microcomputer-interfaced data acquisition system for chemical kinetics (interfacing with laboratory analogue instruments) has been developed. Analogue signals from instruments used in kinetics experiments are amplifed by a wide-range adjustable high-gain operational amplifier and smoothed by an op-based filter, and then digitized at rates of up to 104 samples per channel by an ADC 0816 digitizer. The ADC data transfer and manipulation routine was written in Assembler code and in high-level language; the graphics package and data treatment package is in Basic. For the various sampling speeds, all of the program can be written using Basic-Assembler or completely in Assembler if a high sampling rate is needed. Several numerical treatment methods for chemical kinetics have been utilized to smooth the data from experiments. The computer-interfaced system for second-order chemical kinetic studies was applied to the determination of the rate constant of the saponification of ethyl acetate at 35°C. For this specific problem, an averaging treatment was used which can be called an interval method. The use of this method avoids the diffcully of measuring the starting time of the reaction. Two groups of experimental data and results were used to evaluate the systems performance. All of the results obtained are in agreement with the reference value.

Mathematical modeling of the dynamical properties of analog instruments using first- and second-order differential equations

The simplest optimal transfer function is found by means of a multistep procedure [2]. The procedure entails the exhaustive sequential inspection of transfer functions, beginning with WI(p) = I/(Tp + i), followed by successive incrementation of their structural complexity from one step to the next and the determination of the optimum coefficients of the transfer function of the adopted structure in each step. ~ This set of values of the coefficients of the transfer function is considered to be optimal when a quadratic functional of the difference in the values of the experimental and theoretical output signals is minimized.

Measurements of coda buildup and decay rates of western Pacific P, Po, and So phases and their relevance to lithospheric scattering

We use empirical functions to characterize the shape of band‐passed P, Po, and So coda envelopes of 93 earthquakes. The data sets consist of earthquake data from the western and northwestern Pacific recorded by arrays of several stations and include both hydrophone and geophone recordings on analog and digital instruments. Each earthquake was band‐passed into six octave‐wide frequency bands between 0.8 and 50 Hz. The empirical function (a Poisson function, Pn(γ,t) = A γn+1 tn e−γt /n!) has parameters A (a measure of energy), γ (falloff rate), and nç//γ (time of the maximum). The study showed that these parameters varied in systematic ways. Po/So area (A) ratios were found to be considerably higher for hydrophone data in the 20°–35° range than for geophone and hydrophone data in the 8°–20° range. The difference was significantly larger than between vertical and hydrophone data in the same range. In some instances a strong frequency dependence or “reverse dispersion” of the time of maximum amplitude (n/γ) was observed, with the lower (1–2 Hz) frequencies arriving up to 25s later than the higher (10–20 Hz) frequencies. P, Po, and So average falloff rates ã vary systematically with frequency, where the lowest frequencies most commonly have the minimum falloff rates and the middle frequencies have the maximum falloff rates. The variation in falloff between earthquakes is large, with the trends only becoming apparent upon averaging many measurements. A strong increase in falloff rates at about 3 Hz may be associated with a decrease in the amount of scatterers with scale lengths of about one half the wavelength of a 3‐Hz compressional wave, which is about 1.3 km. Falloff rates were seen to decrease with epicentral range, reflecting an increased scattering with length of propagation path. The scattering that produces the coda is thus not concentrated in the source region but distributed along the propagation path. Falloff rates were seen to decrease with increasing age of crust. The difference may be due to the different average age of the lithosphere in these two geographical areas. Earthquakes at a depth of 100–300 km have systematically lower Po falloff values than shallower events. This effect is clearly seen in trench earthquakes and indicates that significant scattering occurs within (or near) the deeper buried part of the subducting plate. The So/Po falloff ratio is a factor of 2 lower for the hydrophone data than for the geophone measurements. This difference is most likely due to conversion of shear waves at or below the seafloor. If we assume that the coda decay is controlled by intrinsic attenuation, then measurements of coda decay can be converted into estimates of the quality factor Q. At 10 Hz our falloff rates give QPo = 1250, which is a reasonable number for a compressional wave quality factor in the uppermost mantle, and QSo ≈ QPo/2 The low snear wave Q is in disagreement with inferences made by other observers. However, the fact that the falloff rates are fairly constant in the frequency range 5–30 Hz but vary with propagation distance suggests that attenuation cannot be the only phenomenon determining the decay of the coda. Other factors, such as reverberations in the water column, may play an important part in the coda formation as well and may bias these estimates Q.

Do patients sleep in the hospital?

T HE PURPOSE of this study was to compare 14 sleep characteristics of hospitalized adult patients with those of nonhospitalized healthy adults who were in their usual sleep environment. Although it is presumed that patients sleep less than adequately during hospitalization, delineation of the actual nature of sleep in the hospital and comparison with a similar group of nonhospitalized subjects has not been done. The conceptual framework for this study is based on a taxonomy of sleep factors and characteristics that delineates sleep disturbance, sleep effectiveness, and sleep supplementation. A descriptive design was used to collect study data from subjects hospitalized at a University hospital and from subjects with residences in a southwestern community. The Verran-Snyder-Halpem (VSH) Sleep Scale, used for data collection, is a visual analog instrument. Subjects completed the VSH within 2 hours of awakening in the morning. The sample of 76 hospitalized adults ranged in age from 20 to 81 years. The 48 healthy adults

Islamicate Celestial Globes: Their History, Construction, and Use by Emilie Savage-Smith

670 Book Reviews TECHNOLOGY AND CULTURE enon analogous to the new history of science movement in Latin America) gives great hope for an explosive expansion of our knowl­ edge of this area. Thomas F. Glick Dr. Glick is the author of Islamic and Christian Spain in the Early Middle Ages and numerous essays on the transmission of techniques from the Islamic to the Hispanic worlds. Islamicate Celestial Globes: Their History, Construction, and Use. By Emilie Savage-Smith. Washington, D.C.: Smithsonian Institution Press, 1985. Pp. ix + 354; illustrations, notes, bibliography, indexes. Paper. This comprehensive study was initiated when Emilie Savage-Smith was asked to read the Arabic inscriptions on a globe acquired by the Smithsonian Institution’s National Museum of History and Technol­ ogy (now National Museum of American History). Becoming in­ trigued with the globe, she undertook a more detailed survey of it. This led to a ten-year project of research into Islamicate globes. (“Is­ lamicate” as opposed to “Islamic” is defined by the author on page vi: . . Islamicate can be used to refer to objects or cultural features that are not related directly to the religion but are often based upon traditions taken over from other cultures and nurtured and developed by Muslims and non-Muslims alike.”) She sought out globes in public and private collections in America, England, France, Egypt, and other countries. Each globe was examined, photographed, and documented. The results of this research are presented here in three ways. First, there is a descriptive catalog in which the globes are divided into three major categories. For each of the 126 globes (with a further six in an addendum), the location, date, and maker’s name are given, with occasional omissions when the data were not available. The markings and construction are described briefly, and the entry ends with cita­ tions from modern writers. Second, tables of the basic characteristics of the globes are provided. Third, the major Arabic inscriptions on the globes are given. If this detailed and scrupulous cataloging of all the known Islamicate globes were the only content of the book, it would still have provided us with a valuable addition to the literature on astronomical instruments; but the work has further merits. The development of the techniques of globe making from GrecoRoman into Islamic times is fully discussed. The contributions of various astronomers to the different features that may appear on celestial globes are documented, thus placing Islamicate globes clearly in their historical context. Considerable attention is paid to the con­ struction of globes. The material could be wood, papier-mache, or metal. The last was the most common, usually an alloy of copper and lead with small amounts of zinc and tin. They were made by three TECHNOLOGY AND CULTURE Book Reviews 671 methods. In the first, two hollow hemispheres were cast, then soldered together with an internal backing ring. Seamless globes were made either by cire-perdu casting or by hammering the sheet metal around a series of spherical anvils. The engraving of the various markings is also described in detail. These included constellations, stars, ecliptic circle, equator, latitude circle, and so on. In order to make full use of a globe, it was necessary to mount it with a meridian and a horizon ring, set to the latitude of the observer. Globes could be used for didactic purposes in much the same way as armillary spheres, but they were also used by astronomers and astrologers as analog instruments for deriving astronomical data such as the risings and settings of the sun and the stars, altitudes of those bodies at given times, and so forth. Somewhat analogous procedures were used with the astrolabe. In­ deed, some useful comparisons are made between globes and astro­ labes—both plane and spherical. The third, fourth, and fifth chapters are concerned mainly with a detailed description of the Smithsonian globe. Chapter 3 discusses the attribution of the globe from its technical and astronomical features, while chapter 4, contributed by art historian Andrea P. A. Belloli, ex­ amines the globe as an art-historical document. Both approaches yield the specific attribution to a certain Qa’ im Muhammad, who worked in Lahore in the early...

Tin in Antiquity: Its Mining and Trade throughout the Ancient World with Particular Reference to Cornwall by Roger David Penhallurick

TECHNOLOGY AND CULTURE Book Reviews 671 methods. In the first, two hollow hemispheres were cast, then soldered together with an internal backing ring. Seamless globes were made either by cire-perdu casting or by hammering the sheet metal around a series of spherical anvils. The engraving of the various markings is also described in detail. These included constellations, stars, ecliptic circle, equator, latitude circle, and so on. In order to make full use of a globe, it was necessary to mount it with a meridian and a horizon ring, set to the latitude of the observer. Globes could be used for didactic purposes in much the same way as armillary spheres, but they were also used by astronomers and astrologers as analog instruments for deriving astronomical data such as the risings and settings of the sun and the stars, altitudes of those bodies at given times, and so forth. Somewhat analogous procedures were used with the astrolabe. In­ deed, some useful comparisons are made between globes and astro­ labes—both plane and spherical. The third, fourth, and fifth chapters are concerned mainly with a detailed description of the Smithsonian globe. Chapter 3 discusses the attribution of the globe from its technical and astronomical features, while chapter 4, contributed by art historian Andrea P. A. Belloli, ex­ amines the globe as an art-historical document. Both approaches yield the specific attribution to a certain Qa’ im Muhammad, who worked in Lahore in the early decades of the 17th century. Chapter 5 is a history of star names based on the Smithsonian globe. Classical Greek and other pre-Islamic sources, traditional Bedouin names, and classical Arabic terminology are adduced in order to provide a comprehensive ances­ try for the names of lunar mansions, constellations, and major stars. This is an exhaustive study of a useful—and often beautiful—ar­ tifact. It will be of great value to historians of science and technology. Although other information may come to light to supplement the data presented by Savage-Smith, it is likely that this book will remain the standard work on the subject for many years to come. Donald R. Hill Dr. Hill is Honorary Research Fellow in the Department of the History and Phi­ losophy of Science, University College, London. His publications include translations of the major Arabic machine treatises; Arabic Water-Clocks (Aleppo, 1981); A History of Engineering in Classical and Medieval Times (La Salle, II!., 1984); and numerous papers on Islamic technology. Currently he is working on Mechanical Engineering in Islam for Cambridge University Press. Tin in Antiquity: Its Mining and Trade throughout the Ancient World with Particular Reference to Cornwall. By Roger David Penhallurick. Lon­ don: Institute of Metals (1 Carlton House Terrace SW1Y 5DB), 1986. Pp. xiii + 271; illustrations, maps, notes, appendix, bibliog­ raphy, index. £29.95; $59.00. Available from Institute of Metals 672 Book Reviews TECHNOLOGY AND CULTURE North American Publications Center, Old Post Road, Brookfield, Vermont 05036. Roger Penhallurick has undertaken an enormousjob of research— to describe the occurrences of tin in Africa, Asia, and Europe, and to determine when and how tin was first used and how it continued to be exploited. Fulfillment of this task requires knowledge of all the geological literature on Old World tin and all the archaeological and archaeometallurgical literature on early sites from Britain to China. That Penhallurick does not successfully accomplish this in all cases is not surprising, but he does bring extraordinary insights into tin win­ ning in Cornwall, his home. His intimate knowledge of all aspects of Cornish tin—geology, mining and miners’ tales, historical and anti­ quarian literature, associated artifacts and their find circumstances— makes this book an important contribution to the understanding of tin in antiquity. Penhallurick clarifies the nature of the tin deposits accessible to the ancient Cornish miner. He believes that alluvial or placer tin was never very important and that shode tin (surface outcroppings) was signif­ icant only as a guide to the tin grounds buried at depths of as much as 10 meters during geological history. The popular (among archae­ ologists) misconception of Cornish tinners panning streams for allu­ vial cassiterite—similar to our view of the California ’49ers (which also...

Recommendations for Measurements on Inverters for Photovoltaic Applications

The most complex and most vulnerable component in a photovoltaic system is the inverter. Its quality influences the efficiency and reliability and thus the economy of the total PV system in a high degree. For optimal system design, it is therefore important to know exactly the inverters attributes of which the most important is efficiency in the whole power range a PV system operates. For precise efficiency measurements the specific conditions around the inverter have to be taken into consideration which are mainly: input ripple in current resp. voltage, non-sinusoidal inverter output and variable power factor. It is therefore important to use only instrumentation which is able to cope with these boundary conditions. The basic measurement scheme is given in Figure 1. The most critical aspect is that current and voltage may not be in phase at the inverters inand output. Power measurements are therefore only valid, if current and voltage are multiplied instantaneously (multiplication of mean effective-values may lead to substantial faults). This can be done by using fast electronic equipment working with sample(and multiplying) rates above 10 KHz or with analogous instruments. Integrating instruments of this type are the well-known

Development of a Compact Digital Reactivity Meter and a Reactor Physics Data Processor

Reactor physics tests at initial startup and after refuelings are performed to verify the nuclear design and to assure safe operation. Analog computers and instruments are widely used for the acquisition of data, and these data are reduced by hand. These conventional procedures, however, require much time and labor. Since there has been great progress in the development of digital computers and devices, these procedures are digitalized, which successfully reduces the time and labor required for reactor physics tests.

An Overview of the Use and Installation of Electrical Databus Cable in an Industrial Process Plant

Digital control of process equipment has become a major new tool, providing efficient solutions to today's more exacting and complex manufacturing needs. A databus cable transmits high-speed logic signals, interconnecting these digital control systems. A databus cable's electronic function is thus far more sophisticated than customary analog instrumentation or control cable. The presented information will assist the user in the analysis, design, selection, and installation of databus cable.

A technique for ground characterization using automated production drill monitoring

Abstract The monitoring and interpretation of production drill performance data enables a determination of rock mass strength and structure. Correlation of drill performance parameters with changes in intact rock strength, lithology and frequency of fractures has been shown to provide a means of accurately profiling variation in these rock properties with depth. Case studies undertaken in surface operations, using both analog and digital drill monitoring instrumentation, illustrate the potential of this technique for rock mass characterization in surface mine environments.

Panoramic views of strange attractors

An electronic instrument for displaying any perspective of a three-dimensional surface S generated by three time-varying (not necessarily periodic) signals is described. The surface S is a three-dimensional Lissajous figure which need not be a closed curve as is typical of all strange attractors. This analog (not digital) instrument is designed to rotate S along any axis (not just the X-, Y-, Z-axis) through any prescribed solid angles (0°-360°) in the three-dimensional coordinate system in real time. The instrument works as a preprocessor for a standard oscilloscope and is built with components capable of displaying time-varying signals with a frequency spectrum from 0 to 20 kHz. To illustrate some immediate applications of this instrument, strange attractors associated with both autononmus and nonautonomous circuits are presented in many different perspectives and cross sections. In particular, numerous cross sections of these strange attractors which have never been seen before can be easily displayed in any desired perspective in real time. Such cross sections have proved to be most revealing and invaluable in dissecting and uncovering the fine structures of strange attractors.

Detroit's 1987 models: New electronic inroads: Suspensions are the latest conquest in the trend toward total electronic control of all major automotive subsystems

New and updated electronic controls for automobiles are described. The discussion covers engine controls, electric speedometers, low-tire-pressure warnings, analog instruments, and various miscellaneous features.

Reliability in instrumentation

Instrument reliability is defined and related to other measures of durability such as MTTF and failure rate. The need for reliability in modern instrumentation is discussed. A quantitative analysis is given of both maintained and nonmaintained instruments. Various measures for improving an instrument's reliability and availability are described, two of which, redundancy and maintenance, are treated in more detail. Illustrations of specific forms of redundancy are taken from the domain of analogue instrumentation. Preventive and corrective maintenance and their effectiveness are discussed.