bluuebunny/crossref_metadata_2025 huggingface dataset:
How well do workplace‐based assessments support summative entrustment decisions? A multi‐institutional generalisability study
Authors: Ryan Michael S. , Gielissen Katherine A. , Shin Dongho , Perera Robert A. , Gusic Maryellen , Ferenchick Gary , Ownby Allison , Cutrer William B. , Obeso Vivian , Santen Sally A.
Published: January 2024

Background

Assessment of the Core Entrustable Professional Activities for Entering Residency requires direct observation through workplace‐based assessments (WBAs). Single‐institution studies have demonstrated mixed findings regarding the reliability of WBAs developed to measure student progression towards entrustment. Factors such as faculty development, rater engagement and scale selection have been suggested to improve reliability. The purpose of this investigation was to conduct a multi‐institutional generalisability study to determine the influence of specific factors on reliability of WBAs.

Methods

The authors analysed WBA data obtained for clerkship‐level students across seven institutions from 2018 to 2020. Institutions implemented a variety of strategies including selection of designated assessors, altered scales and different EPAs. Data were aggregated by these factors. Generalisability theory was then used to examine the internal structure validity evidence of the data. An unbalanced cross‐classified random‐effects model was used to decompose variance components. A phi coefficient of >0.7 was used as threshold for acceptable reliability.

Results

Data from 53 565 WBAs were analysed, and a total of 77 generalisability studies were performed. Most data came from EPAs 1 (n = 17 118, 32%) 2 (n = 10 237, 19.1%), and 6 (n = 6000, 18.5%). Low variance attributed to the learner (<10%) was found for most (59/77, 76%) analyses, resulting in a relatively large number of observations required for reasonable reliability (range = 3 to >560, median = 60). Factors such as DA, scale or EPA were not consistently associated with improved reliability.

Conclusion

The results from this study describe relatively low reliability in the WBAs obtained across seven sites. Generalisability for these instruments may be less dependent on factors such as faculty development, rater engagement or scale selection. When used for formative feedback, data from these instruments may be useful. However, such instruments do not consistently provide reasonable reliability to justify their use in high‐stakes summative entrustment decisions.
Peritoneal dialysis‐associated peritonitis: A case first for Aquamicrobium
Authors: Mehta Ashin , Yung Timothy , Davis Whitt , Choi Jennifer , Singh Sanjay
Published: January 2024

Aquamicrobium is an aerobic gram‐negative rod which until recently had only been isolated from wastewater and contaminated soil. In 2021, two cases of Aquamicrobium infection in humans were reported. Both were cases of endophthalmitis following cataract surgery. In this manuscript, we describe the presentation and treatment of a 56‐year‐old immunocompetent male who has peritoneal dialysis‐associated peritonitis caused by Aquamicrobium lusatiense. To our knowledge, this is the third reported case of Aquamicrobium infection in humans and the first example of this agent causing peritonitis.
Prepulse inhibition and the call alert in emergency medical services
Authors: Heathcote Scott D. , Blumenthal Terry D. , Swerdlow Neal R.
Published: January 2024

In emergency medical services, paramedics are informed of an emergency call by a high‐intensity acoustic alarm called the “call alert.” Sudden, loud sounds like the call alert may cause a startle response and be experienced as aversive. Studies have identified an association between the call alert and adverse health effects in first responders; conceivably, these adverse health effects might be reduced by modifying the call alert to blunt its startling and aversive properties. Here, we assessed whether the call alert causes a startle response and whether its startling and aversive properties are reduced when the call alert is preceded by a weak acoustic “prepulse,” a process referred to as “prepulse inhibition” (PPI). Paramedics (n = 50; 34M:13F:3 not reported; ages 20–68) were exposed to four call alerts (two with and two without a prepulse) in counterbalanced order. Responses were measured using electromyography (measuring blink amplitude), visual analog scales (quantifying perceived call alert intensity and aversiveness), and an electrocardiogram (assessing heart rate). Paramedics responded to the call alert with a startle reflex blink and an increased heart rate. Acoustic prepulses significantly reduced the amplitude of the call alert‐induced startle blink, the perceived sound intensity, and the perceived “dislike” of the call alert. These findings confirm that the call alert is associated with an acoustic startle response in paramedics; adding a prepulse to the call alert can reduce its startling and aversive properties. Conceivably, such reductions might also diminish adverse health effects associated with the call alert in first responders.
Prevalence, incidence, risk factors and residual risk associated with viral infections among eligible Brazilian blood donors
Authors: Santos Ana Paula Alves , Rios Danyelle Romana Alves , Trindade Clara Lemos Carneiro , Oliveira Fernanda Eshtefane Garrides , Oliveira Milena Batista , de Melo Saulo Nascimento , Belo Vinícius Silva
Published: January 2024

Knowledge regarding the profile of eligible blood donors presenting positive results in laboratory screening is essential for reducing transfusion‐transmitted human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV). Our study aimed to evaluate the prevalence, incidence, predictor variables and residual risk (RR) of HIV/HBV/HCV in blood bags donated in Minas Gerais, Brazil. This study analysed data retrieved from the records of a large blood bank relating to donations collected at multiple centres within the period 2012–2018, during which 1 991 120 blood bags were screened using immunoassays and nucleic acid tests (NATs). Multilevel modelling was used to investigate the association between sex, civil status and age group with HIV/HBV/HCV. RR was estimated from the incidence values (restricted to negative and positive tests within the study period) and window periods for infections. The prevalence in first time donors, incidence and RR of HCV (223.73 cases per 100 000; 54.84 per 100 000 persons‐year and 1.6527 per 100 000, respectively) were higher than those of HIV (172.65 cases per 100 000; 28.25 per 100 000 persons‐year and 0.8514 per 100 000) and HBV (168.17 cases per 100 000; 18.54 per 100 000 persons‐year and 0.5588 per 100 000). The odds of acquiring infection were greater in male, single and older donors. Sixteen donors were identified as seronegative and NATs+ during the 7‐year span of the study. Our study has clarified some spatiotemporal trends regarding HIV/HBV/HCV infections in donated blood in Brazil. The results will contribute to the formulation of directives addressed to high‐risk donors.
Aeronautic Instruments: General Principles of Construction, Testing, and Use
Authors: Hersey Mayo D.
Published: January 2024

This paper, which is a contribution from the Aeronautic Instruments Section of the National Bureau of Standards, affords a brief sketch of the general principles of such instruments. The discussion takes up successively matters relating to the construction, the testing, and the practical use of instruments for aircraft. In each case principles rather than details are emphasized. In a few instances particular instruments are described or the results of particular investigations stated, in order to illustrate the principle involved. The paper, however, does not pretend to serve as a final or comprehensive report on the subject.

That the general field of aeronautic instruments is a less familiar one to the engineer at large than it logically ought to be, is probably due to the confidential character of the work which has gone forward during the war. Now that attention is again directed to civilian aeronautics the subject of instruments takes on great importance for two chief reasons: first, because the efficiency and safety of air navigation, especially in clouds, depends on the reliability of the instruments which are used; and second, because the whole future development of aeronautic engineering rests upon the measurement of aircraft performance, which requires suitable instruments of precision.
Malleable Castings
Authors: Touceda Enrique
Published: January 2024

Malleable-iron castings, according to the author, are regularly made weighing as high as 500 lb., with an ultimate strength of 50,000 lb. per sq. in. and an elongation of 10 per cent or over. With these properties in mind he compares such castings with gray-iron and steel castings, showing that with respect to the former the malleable casting has equal physical properties, costs no more, is lighter in weight and is not liable to breakage. More than 70 per cent of the steel castings produced in this country, it is stated, are not annealed and are in a state of internal strain. Annealed malleable castings are free from such strain, are less expensive to produce, and in the author’s opinion will stand more abuse in service. Their use is therefore indicated and recommended for any part of such size as can be successfully made where strength combined with ductility and low cost per pound is essential.
Die Castings
Authors: Pack Charles
Published: January 2024

The die-casting process, according to the author, is best adapted to alloys of comparative low fusing points, such as those of zinc, tin, lead and aluminum. While it is stated that no general rules can be laid down governing the design and application of die castings, the paper nevertheless outlines the general properties of the various alloys used and their fields of application and gives particulars regarding such limitations as maximum weight of casting, minimum wall thickness, minimum number of threads and minimum diameter of holes that can be cast, draft for cores and side walls, etc.
An Improved Form of Weir for Gaging in Open Channels
Authors: Herschel Clemens
Published: January 2024

In the following paper are presented the results of a series of investigations on weirs which should mark an epoch in the measurement of water by that means. Asked by the Power Test Code Committee of The American Society of Mechanical Engineers to advise it with regard to weir measurements, and supplied by Engineering Foundation with the necessary funds to conduct the experiments, the author devised an entirely new weir which was tested in the Hydraulic Laboratory of the Massachusetts Institute of Technology. The tests revealed that for discharges of from 0 to 9.55 cu. ft. per sec. per ft. of weir length, the limits covered by the experiments, the quantity of water flowing, Q, was directly proportional to the difference, d, in two pressures, one measured just upstream of the weir, corrected automatically for the velocity of approach, and the other measured at the crest, the formula being Q = 5.50 d. The weir, which bears no resemblance to the sharp-edged weir now in use, has a 2:1 slope of approach to the crest. The crest is made in the form of an arc of a circle and is hollow for observing the pressure at that point. The nappe of the stream is supported for a short distance beyond the crest by another 2:1 slope. The paper opens with a résumé of the history of weir measurements and contains descriptions and diagrams of the apparatus and tests of the new weir, with tabular and graphic reports of the results obtained.
Locomotive Feedwater Heating
Authors: McBride Thomas C.
Published: January 2024

This paper describes a system of locomotive feedwater heating which makes use of the so-called open type of heater in which the exhaust steam comes into direct contact with the cold feedwater. The author describes the construction and operation of the heater and discusses the coal saving, water saving, and possibilities of increased capacity due to locomotive feedwater heating. These are discussed first from a theoretical standpoint and second, from the practical standpoint based upon the reports of actual tests. Tables and curves based on tests are presented and analyzed and the paper is concluded with a discussion of the question as to whether the exhaust steam taken by the feedwater heater would cause trouble with the draft. From actual operating conditions the author states that “there was a surplus of exhaust steam left available for the draft.”
Tight-Fitting Threads for Bolts and Nuts
Authors: Lord Chester B.
Published: January 2024

Although in general the thread forms now in use are quite satisfactory, perfection has by no means been reached. There is still considerable search for what the author of the following paper terms “a thread that will not loosen,” and in the preliminary portion of his paper he discusses the fundamental principles involved in the manufacture of threads. The problem to be solved, he states, is as follows: “Without sacrifice of strength, without increase of rejection, without additional manufacturing costs, find a method whereby a male and female thread of the same lead and pitch diameter may be made after repeated loosenings to fit right without the aid of a locking device.” The reasons for departing from accepted practice are presented and discussed, and as a result of experimental work, the author draws the following conclusions: (1) The cause of stripped threads is lack of room into which the metal can flow; (2) The pitch diameter should be the same in both threads; (3) The lead should be the same; (4) The thread angle should differ by not more than 10 deg.; (5) The limits for the inside diameter of nut need not be adhered to closely, as the inner part of the nut thread holds very little, if any; (6) The outside diameter of plug and pitch diameter of both plug and nut are important and should be adhered to fairly closely.
Foundations for Machinery
Authors: Akimoff N. W.
Published: January 2024

The purpose of building foundations is clearly defined and differs radically from that of providing substructures for machinery. Considerable contradiction can be found in blindly applying the principles of the former to the latter, and the results are sometimes so unsatisfactory as to necessitate the use of cushions and other yielding means, thus entirely undermining the very theory on which the foundation was supposedly built.

Vibrations arise from either lack of balance or from other causes. The proposed theory contemplates the latter, the problem of balancing being considered as capable of complete solution by suitable treatment. After briefly considering the nature of possible displacements of the foundation as acted upon by various causes leading to vibrations, the author introduces, by way of illustration, a double pendulum, a few experiments with which form the basis of his theory. Means for localizing the expected vibration and of controlling the resulting periods are then illustrated in a working sketch of the proposed arrangement.
Power Applications to Cotton–Finishing Plants
Authors: Loeb Leo
Published: January 2024

The following paper presents an analysis of the power applications to cotton-finishing plants in which, under ordinary conditions, the steam required for processing is greater than that for power development. The generation of power and of steam and the applications to the driving of process machinery are traced briefly from the boilers to the motor applications. Charts are presented showing the steam consumption and the proportion of the exhaust steam converted into work and available at the exhaust for different types of prime movers. Illustrations of typical drives are included.
Creosoted Wood–Block Factory Floors
Authors: Ericson Lambert T.
Published: January 2024

This paper deals in a broad way with the problems involved in constructing creosoted wood-block factory floors. The character of the timber commonly used is first discussed; then the problems commonly encountered and the essential requisites for success enumerated. The reasons for the use of thoroughly air-seasoned lumber for solid foundations and for waterproof and elastic binders are also given. The field which may be covered with floors of this character is next described, with the conditions commonly encountered. It is also shown that the conditions encountered in factory floors vary so extremely that it is impossible to lay down general specifications covering the treatment and installation. It is demonstrated that this is a specially which should be handled by those who are thoroughly expert in the work. Methods are described which will permit engineers to specify and build creosoted wood-block factory floors without entailing any risk of the failure of the same. It. is recommended that the manufacturer shall furnish creosoted wood-block factory floors upon an installed basis so as to obviate a division of responsibility and to insure the successful installation.
The Armor-Plate and Gun-Forging Plant of the U. S. Navy Department at South Charleston, W. Va.
Authors: Freeman Roger M.
Published: January 2024

The magnitude of such a project as the establishment of the Navy-owned, built and operated Naval Ordnance Plant at South Charleston, W. Va., has made it impossible for the author to give details on all points of the development of the plant. He describes briefly the establishment of the projectile plant and preliminary steps leading up to the actual construction of the armor-plate and gun-forging plant, a general description of which is the main object of the paper. The general layout of the plant and transportation facilities are covered and then the author passes to a more detailed discussion of the unusual features of design and construction. Among these are the arrangement of the stockyard alongside the open-hearth building, the 30-ton electric furnaces for duplexing, the electric traveling cranes to carry 400,000-lb. ingots, the original “H”-type of forge shop and treatment plant combined, the 14,000-ton steam-intensified hydraulic press, the twenty 15 ft. wide Carbottom furnaces, the machine shop with three 106 ft. wide aisles, and the gun treatment building, the high portion of which contains a 75-ton crane of 104 ft, span on rails 165 ft. above the floor level which serves a 10 by 105 ft. high electric-treatment furnace placed in a concrete pit 55 ft. deep. The 23 electric traveling cranes, twenty of which are 75-ton or larger and three of 250 tons capacity, are discussed. The 25,000-kw. electric substations, the 6500-hp. boiler plant and the 25,000,000-gal. reservoir are also discussed briefly.

The paper concludes by summarizing the various steps in the development, outlining the organization of the project, which was handled entirely within the Navy Department, giving in round numbers construction costs, and reviewing briefly the progress of construction of the plant which is now substantially completed.
Capacity Tests of Dry-Vacuum Pumps by the Low-Pressure Nozzle
Authors: Redfield Snowden B.
Published: January 2024

The method of testing moderate-vacuum pumps described in this paper has a number of advantages. A nozzle is used in which the downstream or back pressure is higher than the critical. This permits the determination of several values of volumetric efficiency over a range of vacua without changing the nozzle. The method of plotting of results described by the author is a graphic proof of the accuracy of the theory of the nozzle and permits ready estimation of approximate performance of a given pump.
Report Upon Efficiency Tests of a 30,000-Kw. Steam Turbine
Authors: Reynolds Herbert B.
Published: January 2024

During 1920 the installation of three 30,000-kw. General Electric turbines was completed at the 59th Street power station of the Interborough Rapid Transit Company, New York City, complete tests upon one of which form the subject of the present paper.

These turbines are of the straight Curtiss impulse type, having 20 pressure stages, each pressure stage consisting of one velocity stage. The normal steam pressure at the throttle is 225 lb. per sq. in., abs. the steam being superheated 150 deg. fahr., and exhausted into a vacuum of 29 in. Hg. The speed is 1500 r.p.m. In addition to the primary steam inlet a secondary valve is provided which opens after the load reaches 24,000 kw. and which enables the turbine to carry a load of 35,000 kw.

The turbine tested was installed on a new reinforced concrete foundation. As no expansion joint was provided between the turbine and condenser, novel spring supports for the condenser were provided which are described in the paper.

The lowest water rate obtained during the tests while operating under normal conditions was 11.03 lb. per kw-hr., while the highest Rankine-cycle and thermal efficiencies obtained were 75.5 per cent and 25 per cent, respectively. Results of tests on the condensers and auxiliaries are also given in the form of tables.

The results obtained in these tests of a large power-station unit form a welcome addition to the data of tests of turbines of the same capacity installed in 1915 at the 74th Street power station of the company, reported in a paper presented before the Society in 1916, by H. G. Stott and W. S. Finlay, Jr.
Avoidable Waste in Car Operation — The Container Car
Authors: Sanders Walter C.
Published: January 2024

This paper describes the “container” cars which have recently been placed in service on the New York Central Lines.

The advantages claimed for the container car are that less-than-carload lots of freight, mail and express may be shipped with a material saving of time to the shipper and the railroad company, in that the container car may be rapidly unloaded and reloaded. The car will also permit the railroad to secure the maximum mileage out of rolling stock.

Valuable commodities of all kinds can be transported from consignor to consignee inviolate from damage by fire, weather, breakage or theft, also eliminating to a great extent rehandling, trucking and checking.
Cotton–Ginning Machinery
Authors: Gillespie Solomon E.
Published: January 2024

Of the two classes of cotton grown in the United States — sea island or long-staple, and upland or green-seed — the former does not adhere to the seed and the lint can be pulled off clean by running it through rollers set close together, leaving the seed behind. Upland cotton, on the other hand, adheres to the seed, and the present paper is devoted to a description of the apparatus developed since Eli Whitney’s epoch-making invention in 1792 for mechanically handling the raw seed cotton, removing the lint therefrom, and forming it into shape suitable for delivery to the baling press.

The cotton-ginning process comprises (a) elevating the cotton from the wagons in which it is brought to the ginnery to (b) a cleaner where the dirt, sand, leaf trash and other foreign substances are extracted; (c) elevating the cleaned cotton to (d) feeders which deliver it uniformly to (e) the gins where the lint is removed from the seed by the teeth of circular saws mounted at close intervals on a rotating shaft, from which teeth it is (f) cleaned off pneumatically and (g) carried to a condenser, where it is formed into a “bat” and delivered to a press box for packing, wrapping and pressing. The latest developments of the various devices employed in these steps are described and illustrated in the paper, and the author has included much valuable information for designers in the way of dimensions, relative proportions, speeds of operation, etc.
The Accuracy of Boiler Tests
Authors: Cotton Alfred
Published: January 2024

This paper points out the unavoidable inaccuracies involved in reports of boiler tests and the absurdity of assigning values carried out to the one-hundredth of one per cent to items which cannot possibly be measured so closely.

The various factors which enter into boiler-test computations are taken up one by one and errors which may be made are covered and the best methods of reducing them considered.

The most important elements are of course the determinations of water and coal used, and of steam produced, both as to quality and quantity. It is shown how the error in obtaining the B.t.u. in the coal burned may easily reach 2.5 per cent in either direction, the water evaporated may be at least one per cent out of the way, and hence the efficiency reported may be 3.6 per cent too high or low.
Boiler-Room Performance and Practice of Colfax Station, Duquesne Light Company
Authors: Clarke C. W. E.
Published: January 2024

The paper describes in detail the operation of the boiler plant of the Colfax Station of the Duquesne Light Co., located at Cheswick, Pa. There are included sample analyses of fuel and ash, the piping schedule, temperature and CO2 records, typical water analyses, observations of dissolved oxygen in boiler feedwater, boiler-test data and a typical heat balance covering four months.
Diesel-Engine Clutch Used in the German Submarine “U-117”
Authors: Nicholson W. H.
Published: January 2024

The purpose of this paper is to give to American builders of Diesel engines the benefit of the author’s knowledge of German Diesel-engine clutches obtained at the time of the dismantling of ex-German submarines in the United States. The U-117’s clutch is described in detail and other types of German Diesel-engine clutches are covered generally.
Safety Engineering in the Compression of Gases
Authors: Risteen A. D.
Published: January 2024

The purpose of this paper is to outline a few of the chief hazards that are associated with the compression of some of the gases in common use in industry. Among the gases considered are air, oxygen, nitrogen, argon, carbon dioxide, hydrogen, acetylene, ammonia, and chlorine. The preparation, utilization, storage, or transportation of the gases, except when some of these items may happen to have an important bearing upon the actual operation of compression, are not discussed. As to the mechanical strength of the apparatus that is used to effect the compression, the paper deals only with the things that are likely to happen even when the apparatus itself is strong enough to withstand the stresses that are thrown upon it in the course of its normal operation.
Hydroelectric Developments in Ontario
Authors: Gaby F. A.
Published: January 2024

Preliminary estimates of the available water power in Ontario indicate a total of 6,000,000 hp., of which 1,300,000 hp. have already been developed. The early developments at Niagara Falls are reviewed, and a detailed description of the recent Qneenston-Chippawa development is given. This development, which is the largest in the world, will ultimately develop 650,000 hp. in ten units operating under 305 ft. head. When this development is complete, the generating capacity at Niagara Falls will be over 900,000 hp. An outline of the work of the Hydro-Electric Power Commission of Ontario is given, showing how it has surveyed and mapped out available powers, years in advance of the necessity of utilizing them, and planning their development, so that when the market for power had developed the power was available.
Lignite Char: Its Production and Possibilities
Authors: Hood O. P.
Published: January 2024

Lignite char is lignite which has been dried and distilled in an oven especially designed for the purpose. About two and one-half tons of raw lignite reduce to one ton of char, the heating value of which is about 12,000 B.t.u. per lb. While raw lignite can be used satisfactorily in large steam-raising operations, the author believes that the search for a means to improve the fuel must continue. American lignites do not briquet well without the addition of a binder, and the Bureau of Mines has therefore been led to investigate the possibilities of an inexpensive carbonizing process and the use of the resulting lignite char direct without briquetting. This process is briefly described in the paper.
Power Required for Cutting Metal
Authors: Parsons Fred A.
Published: January 2024

This paper gives results of an investigation extending over a period of more than ten years, the purpose of which has been to determine the fundamental laws governing milling, turning, planing and drilling operations on the various metals and alloys used in machine construction. In addition to a very large number of tests made on milling machines constructed by the concern with which the author is connected, those reported by Frederick W. Taylor and Professors Bird and Fairfield in the Society’s Transactions have been subjected to analysis, the following variables being studied:

1 The efficiency of the machine

2 The rate of metal removal (cu. in. per min.)

3 The average thickness of chip before distortion

4 The front rake on the cutting blade

5 The material being cut

6 The spiral angle or shear on the cutting blade

7 The condition of the cutting tool, sharp or dull.

The author’s results are presented in the shape of formulas and tables by means of which the power required to machine metal in any given case may be calculated, and an example of their use is worked out in detail. Such calculations, however, are tedious, and the author has accordingly devised a slide rule for the purpose, a description of which forms an appendix to the paper.
The Economical Thickness of Insulation in Refrigerator Cars
Authors: Wood Arthur J. , Rice Philip X.
Published: January 2024

The authors call attention to the increasing importance of the economic design of refrigerator cars and discuss the factors which must be taken into account in finding the proper thickness of insulation. The outstanding feature of the paper is the use of alignment charts to determine readily answers to problems involving many variables. By aid of these, or similar charts, one may determine not only the economic thickness of insulation but also the saving which would result from the adoption of the correct thickness compared with any other thickness; furthermore, the economic advantage of one kind of insulation over another may be found.

The paper gives a brief discussion on the economy of using regranulated cork or air spaces in some constructions. It outlines, by aid of average shade-temperature maps, the means of approximating external surface temperatures and notes the results of tests on roofs, sides, and floors as affected by direct sunlight and color of paint.

Reference is also made to the analysis by the authors of the cost of transporting extra weight of insulation, or extra weight of cars as a whole, and the final average figure is found to be about 0.10 cent per ton-mile for transcontinental routes.

All of the above and other factors form a part of the data for a complete solution for economic thickness, whether it is solved by a formula or by charts.
Boiler Test Results With Pre-Heated Air, Colfax Station, Duquesne Light Company
Authors: Clarke C. W. E.
Published: January 2024

This paper describes the apparatus used and gives the results of an extended series of tests carried out in the. summer of 1923 on one of the units of the Colfax Station of the Duquesne Light Company, Pittsburgh, Pa., in which flue-gas air preheaters had been installed. The normal operating rate of evaporating of the boiler employed was the equivalent of 144,000 lb. of water per hour from and at 212 deg. fahr. and the preheater was designed to supply combustion air to the wind box of the stoker at a temperature of 235 deg. fahr. The results obtained show that the efficiency of the unit was increased by from 5 to 7 per cent by the use of the preheater.
Temperature and Stress Distribution in Hollow Cylinders: Applications to Boiler Tubes, Cylinder Liners, and Ordnance
Authors: Dahl O. G. C.
Published: January 2024

This paper contains an analysis of temperature and stress distribution in hollow cylinders. The results should be applicable to tubes, cylinder liners and ordnance.

Whenever a difference in temperature exists between the two walls of a hollow cylinder, stresses are set up. The magnitude of the temperature stresses depends upon the magnitude of the temperature difference and upon its variation with time. The resultant stresses to which a cylinder is subjected are the sum of the temperature stresses and the stresses due to forces and pressures.

The analysis has been limited to the case where the distribution of temperature is symmetrical with respect to the axis of the cylinder and also independent of distance parallel to the axis. In other words, the temperature at any point is assumed to be a function of radius and time only.

Complete solutions are presented for the case where the temperature difference between the two walls is constant. Steady-state solutions are presented for cases where the temperature difference varies sinusoidally with time, where it consists of a sinusoidally varying temperature superimposed upon a constant temperature, and where it undergoes any cyclic variation expressible as a Fourier series.

Numerical examples of computing the stresses in boiler tubes and in the cylinder liner of a Diesel engine are given and the results discussed.
Production Control
Authors: Babcock George D.
Published: January 2024

The conclusions arrived at by Taylor in his paper on Shop Management in 1903, together with the methods he described, were based upon the thesis that every organized effort of human endeavor can be analyzed into its fundamental elements, and that these elements can be forecast and arranged in an orderly sequence that represents the best combination to attain the desired result. The analysis and arrangement of the elements of production brought about the two great divisions of productive effort that are characteristic of modern industrial management and production control — planning and performance.

In this paper the author presents an outline of the subject of production control in manufacturing, taking up for consideration respectively actual output with given equipment; preplanning; the establishment of manufacturing programs; determination of lot sizes; establishment of the production schedule; operation analysis; stores systems; despatching of work; inspection; maintenance; and forms.
The Strength and Proportions of Wheels, Wheel Centers and Hubs
Authors: Eksergian R.
Published: January 2024

The paper outlines an approximate analysis of the strength of wheel centers, particularly as applied to spoke wheels subjected to heavy lateral loads such as locomotive driving wheels. To generalize the work, the subject is extended to a study of other types of wheels with a view to approximating their strength characteristics. Inertia loadings and proportions of flywheels are considered briefly.

After a discussion of classification and loading, the author analyzes the characteristics of bending loadings and stresses, considering first the transmission of torque for wheels with heavy and with light rims, second, direct loading in the plane of the wheel, and third, lateral bending in wheel centers. The design of hubs subjected to a pressure fit is then analyzed, and the additional stresses in a locomotive driving wheel due to the offset load on the crank pin are considered. This is followed by a mathematical discussion of the effect of the shrinkage of tires on the compressive stresses in wheel centers. The counterbalance of locomotive wheel centers follows and the paper concludes with a consideration of inertia stresses and loadings of flywheels with special consideration of rotors for a. c. generators with rotating fields, and of the inertia proportions of flywheels.
Large Oil Engines, With Special Reference to the Double-Acting Two-Cycle Type
Authors: Lucke Charles Edward
Published: January 2024

Efforts to build large oil engines have been growing in number and in variety of means selected to meet marine requirements, stimulated by the success of motorships and the desire to increase their size or utility in prevailing sizes. Possible stationary applications of larger oil engines have also contributed additional motives and other solutions. Much of this work has not been published and is therefore not as well known to the engineering profession as it deserves by reason of its high quality and the foundation it lays for the future. This paper is concerned with a review of some of this work, with special reference to double-acting engines.

One of the problems considered is that of the possibility of raising the mean pressure in the cylinder to get high horsepower per cubic foot of displacement and without rise of maximum pressure to thereby reduce the weight per horsepower. High injection-air pressures, extra injection air, and supercharging of cylinders are included here in addition to studies of shape of combustion chamber, position of sprayer, and design of spray valve. A second one is that of determining the maximum diameter of cylinder that can be operated at very high or at moderate mean pressures without injury to the metal of cylinder, piston, or cylinder head, with particular reference to the effect of special designs of these parts for resisting heat damage at a given heat-generation rate or the corresponding relation of diameter and mean indicated pressure.

A third problem is that of securing results in two-cycle cylinders as nearly as possible equal to those of the earlier developed and more widely standard four-cycle, to determine how close the former can be brought to half the weight per horsepower of the latter on the one hand, and on the other, for the same size of cylinder and similar engine structures, how close to twice the maximum horsepower of a four-cycle engine it may be possible to build the two-cycle. Still another, from the standpoint of double action of the piston, assuming a given diameter and mean pressure or heat-generation rate established in four- or two-cycle single-acting cylinders, and a construction of cylinder, piston and cylinder head not injured for these values, is that of determining the practicability of making both ends develop the same power in both four-cycle and two-cycle engines. This includes the determination of how close to half the weight per horsepower of the single-acting it may be possible to build the double-acting engine or how close to twice the maximum horsepower of the single-acting it may be possible to make the maximum horsepower of the double-acting engine. Some of the double-acting designs published are reviewed, including the rodless piston and the double opposed pistons.
Comparison of Actual Performance and Theoretical Possibilities of the Lakeside Station
Authors: Drewry M. K.
Published: January 2024

To show the degree of perfection in the design and operation of a high-efficiency, straight-Rankine-cycle station, pointing out the magnitude of each individual heat and availability loss occurring in actual practice, is the object of this paper. Operating and test figures of the Lakeside station have been assembled and a comparison of theory and practice has been recorded.
Mechanical Features Affecting the Reliable and Economical Operation of Hydroelectric Plants
Authors: Dow E. A.
Published: January 2024

This paper deals with the subjects of flashboards, trashracks, rack rakes, sluice gates, headgates, penstock valves, air vents, and discharge-measuring devices, from the standpoint of economy and reliability of operation, based almost entirely on the New England Power Company’s practice. It stresses the importance of reducing head losses and leakage and adhering to strength and simplicity in the design of hydraulic equipment.
Torsional Vibrations and Critical Speeds of Shafts
Authors: Lack Arnold , Jahnke Charles B.
Published: January 2024

This paper is an analysis of torsional vibrations and critical speeds of shafts. These magnitudes can be calculated, as shown here, for any engine when all necessary data are given. The various characteristics of torsional vibrations are measured with a special instrument, called the “Torsiograph,” which shows on “torsiograms” the degree of irregularity of rotation.

The stresses in the shaft due to its vibrations are also computed, and means of avoiding dangerous vibrations are shown. Results of tests are given which were performed on: (a) An apparatus for demonstration of torsional vibrations; (b) an experimental horizontal oil engine; (c) a vertical two-cylinder Diesel engine driving two generators; and (d) a vertical four-cylinder marine engine.
Vibration Phenomena of a Loaded Unbalanced Shaft While Passing Through its Critical Speed
Authors: Kimball A. L. , Hull E. H.
Published: January 2024

The purpose of this paper is to present in a clear manner with experimental demonstration a discussion of the peculiar vibration phenomena to which an unbalanced, loaded shaft is subject while passing through its critical speed. First, the basic theory is given from a somewhat new viewpoint,2 after which an experimental demonstration, which gives a quantitative check on the theory, is described.
Phosphor-Bronze Helical Springs From the Standpoint of Precision Instruments
Authors: Brombacher W. G.
Published: January 2024

This paper gives the results of tests made on phosphor-bronze helical springs investigated at the Bureau of Standards to obtain knowledge useful in the design of springs for precision instruments. The characteristics of the spring material, the method of construction of the springs, the apparatus in which the springs were tested and the procedure followed are set forth by the author. The results relate to stiffness, maximum fiber stress, hysteresis, after-effect, drift, and buckling.
Auxiliaries for Motor Vessels
Authors: Morton John W. , Newell A. B.
Published: January 2024

With the vast increase in motorships it is only natural to expect a variety of installations; and the many designs and variety of types of propelling machinery and modes of drive in turn affect the auxiliary equipment.

The great differences that exist in auxiliaries in such factors as weight, space, duty, capacity, cost, etc., without doubt could be minimized.

Determining the right kind and capacity of auxiliaries, in order to reduce first cost and weight and at the same time have the most economical marine plant both at sea and in port, is a somewhat difficult task, because one has to consider the ship’s trade routes, and whether the ship is new or converted.

It must also be remembered that the assumption regarding continual running with full cargo is rather ideal, but as all ships will be equally liable to runs in ballast or with part cargo or load, the results will be relative.

Comparisons between types of machinery are often based on the relative space required, the weight and fuel-consumption values, and the resulting saving in fuel.

While perhaps these are quite fair to the machinery, they are not to the ship as a whole, and are apt to show differences, the benefits of which in practice are never realized.

The comparisons in the paper have been made without bias for or against any particular type of machinery, and in a manner that shows a more true ultimate saving than that attained by other comparative methods.

The differences brought out by the analysis, although showing no one particular type as vastly superior, do show that certain vessels can be built and operated with more profit than others, and they therefore justify a close investigation of ships’ economies when selecting the type of machinery.
The Locomotive Testing Plant and its Influence on Steam-Locomotive Design
Authors: Fry Lawford H.
Published: January 2024

The paper gives a brief history of locomotive testing plants and their contributions to the development of the locomotive. The work done by the Altoona testing plant is told in brief references to the results of tests as reported in various bulletins published by the Pennsylvania Railroad. Contrasts are made of size and economy of locomotives twenty years ago when the first testing plant was built and the present time. One appendix to the paper develops the method used in determining locomotive efficiencies, and another is an extensive bibliography of locomotive testing.
Duty Tests of Vertical Triple-Expansion Pumping Engines, Milwaukee, Wis.: Results Obtained at Riverside Pumping Station
Authors: Cahill Charles A.
Published: January 2024

Milwaukee, Wisconsin, has equipped its new Riverside Pumping Station with three vertical triple-expansion pumping engines. The reason for the choice of engines of this type was their great reliability, high economy, and low cost of maintenance. The author believes that the units A and B recently tested have shown a duty record that has not been equaled to date by any using steam as a working medium for pumping water.
A Research in the Elements of Metal Cutting: Confined to Tool Sharpness, Tool Form, Chip Dimensions, and the Force Involved
Authors: Boston Orlan W.
Published: January 2024

This paper gives an account of an investigation in the fundamental elements of metal cutting conducted in the Machine Tool Laboratory at the University of Michigan. The object of the investigation was to determine a relation between the force on the tool in the direction of cut for a constant cutting speed of 20 feet per minute, and the degrees of tool sharpness, the various tool angles, the width and depth of cut, and the physical properties of the materials cut. Nine representative types of material were cut including three carbon steels, three alloy steels, brass, and annealed and unannealed cast iron. The cutting was confined to straight-line motion on a planer and the tools used were of the end-cutting type. No cutting fluids were used and but one element was varied at a time.

The results show that the clearance angle has no influence on the force on the tool so long as the tool does not drag on the work, that the force on the tool remains constant for a wide variation of keenness of cutting edge, and for thick chips, particularly, the tool edge may be rounded to 1/64-in. diameter without appreciable increase in the cutting force. It is also shown that the cutting force on the tool is reduced in direct proportion to the increase in front-rake angle, all other factors remaining constant. It is shown that thick chips are removed more efficiently than thin chips, and that narrow chips are removed more efficiently than wide chips. The results also indicate that there is an apparent relation between some of the physical properties of the metals and their machinability or the cutting force on the tool for the carbon steels in one group, the alloy steels in a second group, and cast iron in a third group.

A bibliography on metal cutting has been made a part of the paper to enable those interested in the subject readily to locate those articles of interest or value to them.
Industrial-Boiler Efficiencies
Authors: Fitzsimmons Samuel D.
Published: January 2024

This paper presents results obtained with two boilers installed at the plant of the Brown & Sharpe Manufacturing Company, Providence, R. I., and its purport is to indicate the desirability of low furnace-draft velocities and a more effective use of radiant heat. The premise is assumed that more width in the tube sections of water-tube boilers is desirable. Much that is offered is in the form of conjecture.