Slide Rule Research Articles

Clinical specular microscopy. Technic, organization and simple calculator morphometry

The use of specular microscopy (SM) as a routine clinical method for qualitative morphological and quantitative morphometric analysis of the corneal endothelium requires a standardized examination technique. Organizational and apparative means are necessary for the analysis, documentation and storage of the data. The results of the immediate analysis are documented on a result form. The morphological changes are classified in 4 different groups (endothelial, pre-endothelial, retro-endothelial, and non-endothelial changes). The morphometric analysis is performed immediately: the mean cell density (mcd) is estimated by comparing the endothelial mosaic in the camera viewfinder with 3 standardized specular micrographs with known cellular density. The good correlation between the results of estimation and definite counting allows this rapid method to be used as a simple clinical screening techniques. The definitive morphometric analysis is carried out directly from the photographic negative using the fixed frame principle. The mcd and mean cell area (mca), m +/- sd, are determined by a simple method which saves time and money, using a scientific pocket calculator programmed in Basic. A specially designed slide rule serves to define the frame. The calculator may also be used for statistical analyses. This is demonstrated in a group of 127 patients (aged 51-87) before IOL implantation. The mcd and mca of the examined population is 2249 +/- 290 cells/mm2 and 444 +/- 57 microns 2. There is no statistically significant difference in mcd between the right and left eye (t-test: p = 0.93). Although statistically mcd decreases significantly with advancing age (p = 0.05), there is a large range of results in this population.(ABSTRACT TRUNCATED AT 250 WORDS)

Slide rule estimates of Fire Growth

A series of prediction methods has been assembled to provide an analytical basis for estimating fire growth in compartments. Solutions for each prediction method can be made using programmable scientific calculators. Prediction methods are presented for: fire size and growth rates, mass loss rates, radiant heat flux, flame height, radial flame impingement, heat flux to a ceiling, smoke filling of a room, carbon monoxide hazard with smoldering fires, temperature rise in a compartment, ventilation flow rate, flashover occurrence, corridor smoke transfer and filling, smoke concentration, visibility, flame spread rates, and fire burn time. These predictive methods are useful for estimating many of the critical elements related to fire behavior and help provide a better understanding of this complex phenomenon. This report appears as Appendix B inFire Growth in Combat Ships by J. G. Quintiere, H. R. Baum and J. R. Lawson, NBSIR 85-3159.

Database ethics: Decision‐making constraints in an environment of change

Without being as pessimistic as Huxley or as moralistic as Rabelais, it is nevertheless clear that the information industry of the 1980s is facing some wrenching decisions. Money is not pouring in as it did in the ’70s, the novelty of online databases is wearing off, and asserting its presence is a new generation of information users: a generation of personal computer owners to whom a slide rule is an antique (if they know about it), access to information is a right, and science — after a generation of ethical scandals — has lost its aura of sanctity and incorruptibility.

Surveying Computations: Backsight — Turning Point — Foresight

Surveying computations are an integral part of the surveying profession. Until only a few decades ago they were performed by logarithms, mechanical calculators and slide rules. Mathematical models had to be given in forms suitable for the computational means available to the profession. The invention of digital or high-speed electronic computers led to a revolution in data handling and problem solving practices. The application of modern computers and calculators in surveying necessitates a radical reorganization of scientific research and everyday engineering work. Analytical methods of computations have not lost their importance, although the domains of their applications have changed. Computers brought a variety of numerical methods which, together with approximation theory, have become the most important part of surveying computations.

SoundOFF: We Have A Choice

The next dozen years can be the best of times or the worst of times for mathematics educators, depending on how we react to the revolution. I'm talking about the revolution that has already eradicated the slide rule, doomed trig tables, and to borrow a phrase from a president of the Mathematical Association of America, will leave paper-and-pencil long division “as dead as a dodo bird.” The world of mathematical computations will be revolutionized by electronic calculators and computers.

Slide rule for gamma-ray flaw detection

This article describes a slide rule which makes it possible to determine the exposure time quickly and with sufficient accuracy when inspecting steel parts using Cs-137 and Ir-192 as radioactive sources and x-ray films of types RT-1, RM-1, RT-5, etc. The slide rule scales were designed on the basis of experimental data regarding absorption of gamma rays in steel. The slide rule is similar in construction to a normal doublesided slide rule with one slide and a cursor. Gamma-ray flow detection is one of the most common methods of identifying defects using radiation. The films of different components shot by different operators using the slide rule for determining exposure time can be simultaneously developed without visually controlling the photographic density.

A slide rule for calculating the power of an intraocular lens.

We have designed a slide rule to calculate the emmetropizing and iseikonizing power of an intraocular lens (IOL). Like the dial biometer currently used for these calculations, the slide rule is inexpensive, easy to use, simple, and a compact pocket size. It can, however, also be used to calculate postoperative refractive error, corneal power when various keratometers are used, and conversion of refractive correction at the spectacle frame to that at the cornea, or vice versa. All the calculated data are within the accuracy suitable for clinical work.

On the Diffusion of Computer Terminals in an Established Engineering Environment

The introduction of new technologies in existing administrative and technical organizations usually represents a significant investment in equipment and training. A prudent manager will attempt to acquire the equipment needed fast enough to encourage its use while avoiding the inefficiencies of under-utilization. This paper presents a method of applying a mathematical model to the specific problem of predicting the approximate rate at which additional computer terminals should be acquired. The model used is in the form of a “logistics” or “diffusion” function. To apply the model to the Aerospace division of a company, a “calibration” of that organization was required. A questionnaire on the use of hand calculators was submitted to a sample group. At the time of the study, hand calculators had virtually displaced slide rules and desk top adding machines, and about 15 percent of the organization was competing for available terminals of the central computer system. Increased use of terminals and on-line computing was anticipated. The response of the organization to the hand calculator innovation was established by determining a “logistics” or “diffusion” function to fit the sample data. The function was modified to accommodate the additional complexity of the more sophisticated computational capability and then used to predict terminal requirements. This study was undertaken to satisfy a management need to plan for its investment in terminals. At the introduction of an interactive computing system, terminals were requested for individuals or projects. As the number of terminals increased, the number of qualifed users increased faster, and requests for terminals became more numerous. Justifications frequently appeared to be overlapping or duplicative. At this point, a better perspective of the money needed was required, and the study was initiated. The results of the study, together with user requirements data, have been used to expedite the acquisition of terminals.

Turns for the Lorentz group

A geometrical description of the composition law for pure inertial transformations in relativity is developed, in close analogy with the description of rotations by means of turns. This affords a very intuitive and visual image of all problems involving a composition of velocities, and clearly shows the appearance of hyperbolic geometry in relativistic kinematics. The pertinent geometrical constructions as well as some applications are discussed. For the case of light the preceding constructions are surprisingly simple, and from them emerges a connection between the geometrical idea of parallelism angle and the physical Doppler effect. A slide rule which can be used to carry out all needed computations is also described.

Array aperture selection in the presence of inhomogeneous noise

Sonar slide rules tell us that the directivity index of an antenna array increases 3 dB per length doubling per array dimension. This directive gain is against isotropic noise an it is clear that calculation of the true antenna signal‐to‐noise gain must consider the actual noise environment. A less obvious consequence of some noise fields is the existence of finite, optimum array dimensions. This paper presents array gain versus aperture computations for a number of representative inhomogeneous noise environments. The important points are the existence, for some environments, of well defined optimum dimensions beyond which gain actually decreases and other environments in which the rate of return (gain increase versus aperture growth) becomes insignificant. [Work supported by ONR.]

Computer Method for Forced Torsional Vibration of Propulsive Shafting System of Marine Engine With or Without Damping

In the preliminary design of a propulsive shafting system, the additional (vibratory) stress due to torsional vibration is one of the important factors that must be considered in addition to the mean stress induced by the steady torque. In this paper, existing information concerning shaft design is reviewed; procedures formerly performed by slide rule, diagrams, and tabulations are formulated; and, based on the induced formulas, computer programs are developed. For an engine either two cycle or four cycle, single cylinder or multicylinder, and for a shafting system either undamped or damped (inner or outer or both inner and outer), it is required only to change the input data to obtain the desired data for various order numbers of torsional vibrations due to various firing orders of the cylinders. The output data include the natural frequencies and the corresponding mode shapes of the torsional vibrations, the amplitudes of twisting angles, and the vibratory stresses of the shafts. The reliability of the induced formulas and the developed computer programs has been confirmed by agreement between the computer output and existing information.

Engineering Calculations on Microcomputers for Power System Studies

Microcomputers have in recent years become economical for any small business and/or individuals. With their ease of operation, high speed, flexibility, and low cost these units provide the engineer with an extremely valuable tool that enables him to perform the most complex engineering calculation and enhances his ability to make optimization studies of all types with ease. Typical computer systems highlighting the state of the art with recommended features for maximum utilization by engineers are described. Also discussed are programs for calculations such as short circuit, load flow, motor acceleration, voltage drop, sag and tension for overhead distribution, and others. Program development for the small computer is limited only by the resourcefulness and imagination of the user. It is expected that in time these units will become as common in the industry as the slide rule or the programmable calculator.

The use of small, low-cost computers in CAD

Historical considerations have ensured that the majority of CAD systems currently in use have originated from the mainframe environment or, more recently, from the large minicomputer. In the current hardware market, is this state of affairs necessary or desirable? Are all CAD applications so complex and/or resource consuming that expensive systems must be purchased? This paper looks at some aspects of CAD which are appropriate to micro-type computers which are relatively slow in the computer market, but rather faster than an engineer with slide rule or even calculator. Some programming philosophy is included with the view of protecting software investment whilst enabling transfer of code to alternative machines as they become cheaper and/or faster.

Travel-time curves for a simple sea floor model

This paper reviews a simple technique for interpreting the velocity structure of upper oceanic crust from travel-time data of sonobuoy and ocean bottom receiver refraction experiments. The technique does not involve sophisticated digital processing or synthetic seismogram analysis. Interpretations can be carried out with a pencil, paper and slide rule.

Computing grassland and forest fire behaviour, relative humidity and drought index by pocket calculator

Summary A Fire Danger (FD) program for a pocket-sized calculator has been developed to provide easy and rapid calculation of McArthur's fire danger indices for grassland and forest fires, a hazard rating and other measures of fire behaviour, together with rederived ancillary computations of a drought index and relative humidity. This allows the replacement of a number of slide rules, charts, and forms with a single small package which can be used rapidly and accurately in the field or office for research or daily operations. The program has initially been designed for an HP-41C calculator using RP notation and a continuous memory. However no programming skills are required to use the program. The computations are suitable for use by any programmable calculator or computer with a memory of about 2000 bytes. Relative humidity and the fire danger can be projected forward using current or forecast.conditions of atmospheric moisture and a forecast of temperature. The equations which were used are appended.

Automated work sampling with unbiased variance estimates

Work sampling is a work measurement tool that was over simplified during the slide rule era by assuming a binomial distribution for observation data totals. The binomial variance was then used to calculate the variance of the proportion estimate(s) and to determine the necessary number of observations needed to attain a certain accuracy. Now a variety of computer programs are being written to perform work sampling calculations incorporating the same quick, easy, but often biased variance estimates. When a sampling study extends over a relatively long period of time better variance estimates for the proportions are available which are essentially sample variances constructed from observation-round proportions, work shift proportions, or daily proportions. These alternate variance estimates will yield different accuracy claims and different determination of the number necessary additional study days, sometimes larger and sometimes smaller than the classic estimates. In the very practical case of unequal number of observations per round and/or per day these calculations are extremly time without a program but relatively simple in any computer language. A Fortran program is presented which calculates three different accuracies and numbers of additional study days (the classic estimates and two others), marking the one prefered based on the amount of data in the system at that point. Properly operated the program will periodically update a data file with additional study data until the operator is satisfied and terminates the work sampling study. Pace rating of work categories, when appropriate, can also be incorporated by the program to modify proportion estimates.

Practical application of the Einhorn (CIE) Glare Index formula

The paper has a twofold purpose. Firstly, to present a method for reducing basic glare formulae to a form simple enough to apply to routine lighting design problems with no more equipment than a slide rule or simple pocket calculator. Secondly, to show how this method can be applied to Dr. Einhorn's new proposed CIE Glare Index formula* including a detailed step-by-step procedure with a worked example. The paper concludes with a brief comparison of the formula with established glare calculation theory and observation, which suggests that it is a useful compromise between the different national schemes.

Use of a photocopied slide rule to complement limited function calculators

Use of a photocopied slide rule to complement limited function calculators

Computer graphics and computer aided design in mechanical engineering at the University of Minnesota

Engineering design in industry is changing as a result of the application of the new tools provided by the digital computer and interactive computer graphics. This shift is placing new demands on engineering curricula. The engineering graduate today must be trained in the use of the computer and computer graphics as a design tool—in much the same way that engineers in the past used the slide rule and today use the hand-held calculator. This paper summarizes the efforts to integrate computer graphics and computer aided design into the design curriculum in the Mechanical Engineering Department at the University of Minnesota. Specific software packages have been developed for use in teaching engineering graphics and mechanism synthesis and analysis. These packages are discussed in detail, including the hardware used.

Preventive cardiology in practice: A device for risk estimation and counseling in coronary disease

A method for the rapid estimation and display of coronary risk is used in counseling and for following progress in the practice of preventive cardiology. The estimator is a slide rule which computes risk of a future coronary event based on current age, smoking habit, serum cholesterol, and blood pressure levels. The device also displays estimated change in risk based on change in risk factors. The estimates are explained to clients as gross approximations. The slide rule is helpful in personalizing the need and the potential of preventive efforts.