bluuebunny/crossref_metadata_2025 huggingface dataset:
Association between nailfold capillaroscopy abnormalities and autoimmune disease in pediatric populations
Authors: Li Andraia R. , Burke Connor D. , Purvis Colby S. , Lee Lara Wine
Published: January 2022

Objective

Time to diagnosis of autoimmune disease in pediatric populations can take years but nailfold capillaroscopy (NFC) may identify early signs of autoimmune disease. The aim of this study is to assess the association between nailfold capillary abnormalities and autoimmune disease in children.

Methods

A systematic search of PubMed, EMBASE, and Scopus was performed to identify all studies published before March 17, 2021. Observational studies reporting NFC outcomes in children with autoimmune disease and healthy controls (HC) were eligible for inclusion. Odds ratios (OR) and 95% confidence intervals (CI) were pooled using a random‐effects meta‐analytical model.

Results

Nine of 3665 studies reporting on 641 patients (398 subjects, 243 controls) were included. Pediatric patients with autoimmune disease were 9.88 (95% CI 3.16–30.87, I2 = 80.1%) times more likely to have abnormal nailfold capillaries than HC. Of the capillaroscopic features, dilated capillaries (OR 27.90, 95% CI 2.17–349.05, I2 = 59.9%) were the most likely abnormality observed on NFC. This was followed by the likelihood of reduced capillary density (<7 capillaries/mm) (OR 19.91, 95% CI 3.79–105.52, I2 = 0%), giant capillaries (OR 12.87, 95% CI 2.38–69.45, I2 = 0%), hemorrhages (OR 13.89, 95% CI 5.34–36.16, I2 = 0%), and avascularity (OR 10.38, 95% CI 2.20–49.04, I2 = 0%).

Conclusions

Children with autoimmune disease are significantly more likely to have nailfold capillary abnormalities. NFC may be useful in identifying early signs of underlying rheumatic disease and potentially decrease the time to diagnosis for this patient population.
Treatment of vitiligo with 308‐nm light emitting diode: Our experience from a two‐year follow‐up of Chinese patients
Authors: Luan Chao , Hu Yu , Ju Mei , Huang Dan , Zhang Rong‐Lin , Zhang Xiao‐Hua , Tian Pan‐Pan , Zhu Yan , Zhuang Chen , Zhang Jia‐An , Chen Kun
Published: January 2022

Background

A light emitting diode (LED), with a wavelength of 308 nm, has been utilized in the dermatologic treatment of vitiligo.

Objectives

We investigated the efficacy and safety of 308‐nm LED for use in the treatment of vitiligo.

Methods

We conducted a retrospective study of 70 stable‐stage vitiligo patients (with a total of 99 lesions) who received 308‐nm LED treatment at the Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College from June 2018 to June 2020. Treatment efficacy was evaluated after 8 treatment sessions, 16 treatment sessions, and the final treatment session, to estimate the percentage of re‐pigmentation in the treated area. The Kruskal–Wallis test was used for data analysis.

Results

Based on the final treatment session analysis of all 99 lesions, 0 lesions showed no response, 21 lesions showed poor response, 29 lesions showed moderate response, 23 lesions showed good response, and 26 lesions showed excellent response. The efficacy rate was 49.49%, and there was a significant correlation between the six distinct anatomical regions treated and re‐pigmentation grade (χ2 = 13.419, p = .009). Among these regions, facial lesions showed the best response to treatment, while the hands and feet lesions showed the poorest response.

Conclusions

The clinical efficacy of 308‐nm LED treatment is limited based on the treatment area. It demonstrated significant practical application in the treatment of vitiligo.
Advancing leaders and leadership: New Zealand women in respiratory medicine
Authors: Yap Elaine , Mooney Sarah
Published: January 2022

See related editorial
The Viscosity of Five Gases: A Re-Evaluation
Authors: Kestin J. , Wang H. E.
Published: January 2022

The paper contains a re-evaluation of the experimental results for the pressure dependence of viscosity obtained by Pilarczyk and described by Kestin and Pilarczyk. The re-evaluation is based on an improved theory of the oscillating-disk viscometer described by Kestin and Wang. The results for air, nitrogen, argon, helium, and hydrogen are given in graphical and tabular form as well as in the form of empirical equations. The range covered is 1 to 70 atm at 25 C. The results constitute a relative measurement which is based on Gibson and Michels’ data for nitrogen. Very good agreement with previously published data for nitrogen, air, and hydrogen has been reported. In the case of helium no comparative data could be found and in the case of argon there is good agreement with the data published by Michels and others but the difference in absolute values is somewhat higher than for the preceding three gases. The agreement as to rate of change with pressure is excellent. It is believed that the data now reported contain an uncertainty of no more than 0.2 per cent for nitrogen, air, hydrogen, and helium and of not more than 0.6 per cent for argon with respect to nitrogen. The data have been summarized in Table 1.
Convection Heat Transfer and Pressure Drop of Air Flowing Across In-Line Tube Banks: II—Correlation of Data for Ten-Row-Deep Tube Banks
Authors: Gram A. J. , Mackey C. O. , Monroe E. S.
Published: January 2022

New heat-transfer and pressure-drop data within a Reynolds-number range of 600 to 40,000 obtained from model 10-row in-line tube banks are presented in a conventional form. The new data are compared with previously reported results for similar surface arrangements. By a process of cross-plotting, heat-transfer and pressure-drop factors are shown as a function of tube-bank arrangement in a series of curves at constant Reynolds numbers. Correlations for tube-bank geometry are proposed and the precision with which they represent the new and previously published data is discussed.
Cold Extrusion of Unalloyed Titanium
Authors: Sabroff A. M. , Huber O. J. , Frost P. D.
Published: January 2022

The first known successful cold extrusion of titanium was accomplished at Battelle on a project for Wright Air Development Center. Working with commercially pure grades of titanium having 45,000 and 70,000-psi yield strengths, and employing a Battelle-developed fluoride-phosphate coating for titanium, billets 1½ in. diam were forward extruded to bars 1.16, 1.06, and 0.95 in. diam. These correspond to reductions of 40, 50, and 60 per cent. The fluoride-phosphate coating, in combination with a conventional oil-graphite-molybdenum disulphide lubricant, prevented seizing and galling and produced a smooth surface finish. The extruded bars exhibited as high as a 60 per cent increase in strength, yet adequate ductility (10 per cent in 1 in. minimum) was maintained.
Experimental Determination of Gear Tooth Stresses in Large Marine Gears
Authors: Semar H. W. , McGinnis R. E.
Published: January 2022

A successful experimental method to measure gear tooth stresses on large marine gears while the teeth are transmitting load is described. Some results obtained using the method are given and discussed.
The Application of Gas/Liquid Cyclones in Oil Refining
Authors: Van Dongen J. R. J. , Ter Linden A. J.
Published: January 2022

The two-phase flow of liquids and vapors is encountered in many refinery processes. As most final products must be either in liquid form or in vapor form, the separation of the two phases is necessary at some stage in the process. Therefore the problem of separating liquids from vapors efficiently is of interest in oil-refinery practice.
Laminar Flow Over an Enclosed Rotating Disk
Authors: Soo S. L.
Published: January 2022

Laminar flow over an enclosed rotating disk was studied to reduce the inconsistency between previous theoretical and experimental results. Unlike the case of a disk in an infinite fluid medium, the friction-moment coefficient of the enclosed disk is proportional to Re−1 in the laminar range and Re−1/4 in the turbulent range. The latter is accurate for the range of disk diameter to gap ratios between 200 and 50. The former correlation, instead of being an approximation according to simple shear as has been suggested, is shown to be true even when recirculation exists. The deviation from Re−1 relation in the laminar range is shown to be due to the inertia effect of recirculation. The significance of inertia effects in addition to that due to centrifugal force has been pointed out and corrections have been presented. Radial outflow has been shown to be more effective than radial inflow for turbine-disk cooling. It has been shown that rotation of the shroud provides an added sealing effect for a centrifugal machine.
On the Theoretical Analysis of a Dynamic Thermocouple
Authors: Gaylord E. W. , Hughes W. F. , Appl F. C. , Ling F. F.
Published: January 2022

The “dynamic” thermocouple formed by the moving junctions of two dissimilar metals is analyzed theoretically. It is found that if the two leads from the cold junction, in series with a potentiometer, are symmetrically placed in two bodies rubbing over each other, the e.m.f. measured by the potentiometer satisfies Laplace’s equation in terms of the positioning of the leads in the body. The boundary condition is that the potential at any contact area is the Seebeck e.m.f. corresponding to the contact area temperature. It is shown that, in the case of two semi-infinite rubbing bodies with many randomly distributed contacts, small in area compared to the distance between them, the potential measured by thermocouple leads placed at an infinite distance away from the contact areas is the average of the Seebeck e.m.f.’s, corresponding to the contact temperatures, weighted by the square root of the areas.
Transient Interface Temperatures in Plain Peripheral Milling
Authors: McFeron D. E. , Chao B. T.
Published: January 2022

The analytical calculation of tool-chip interface temperature has been extended to the plain peripheral milling process. The solution of the equations presented enables an investigation of the effects of material and process variables to be made from fundamental cutting data. It was found that the intermittent nature of this cutting process increases the percentage of heat flow from the tool-chip interface into the tool as compared with single-point turning. A slight increase in the workpiece temperature has a more pronounced influence on the tool-chip interface temperature than would a similar increase in the tool temperature.
On the Stagnation of Natural-Convection Flows in Closed-End Tubes
Authors: Ostrach Simon , Thornton P. R.
Published: January 2022

An analysis of the laminar natural-convection flow and heat transfer in a closed-end tube with a linear wall temperature and large but finite length-radius ratio is presented. It is found that for a given relation between the two physical parameters of the problem, the flow will fill the entire tube length. Representative velocity and temperature profiles are presented to show the effects of the parameters on the flow and heat transfer.
A Model Method for Determining Geometric Factors in Solid-to-Solid Radiation Heat Transfer
Authors: Tea P. L. , Baker H. D.
Published: January 2022

A model method using light is presented for determining the geometric factors which must be known in order to utilize the Stefan-Boltzmann equation for heat transfer by solid-to-solid radiation. The model source is of unique design and closely approximates a uniform, perfectly diffuse plane source of any shape. The detector of radiation has negligible cosine error. The technique is highly suited to handle problems involving interreflections.
Laminar Mass and Heat Transfer from Ellipsoidal Surfaces of Fineness Ratio 4 in Axisymmetrical Flow
Authors: Ko Shao-Yen , Sogin H. H.
Published: January 2022

The calibration of the heat-mass analog given by Sogin (7) is employed to obtain mean coefficients of heat transfer from the nosepieces of ellipsoid-cylinders to air in axisymmetrical flow. The results for the ellipsoidal surface of axis ratio 4:1 are represented by the equation (hGcpNPr,f2/3)(GSμf)1/2=0.76 in the range of the Reynolds number from 32,500 to 280,000. They are compared with the results of a wedge-flow approximation of the boundary-layer solution and with results from other investigations on related shapes.
Investigation of Burnout Heat Flux in Rectangular Channels at 2000 Psia
Authors: Jacket H. S. , Roarty J. D. , Zerbe J. E.
Published: January 2022

Burnout heat-flux data were obtained under conditions of approximately zero exit quality and bulk boiling at the exit of electrically heated test specimens. These specimens were long, narrow channels with various slot thicknesses, surfaces, materials, and length-to-diameter ratios. Tests were run at 2000 psia and mass velocities from approximately 0.2 × 106 to 3 × 106 lb/hr-sq ft. The effect of inclining the channel at 45 deg also was investigated. The rectangular channel burnout results are in reasonable agreement with data previously obtained for round tubes. A design equation is suggested which yields a conservative estimate of the burnout heat flux in the low subcooling and quality regions for the range of variables investigated herein. A burnout loop and method of operation are described.
Properties of Friction Materials II—Theory of Vibration in Brakes
Authors: Basford P. R. , Twiss S. B.
Published: January 2022

A theory of vibration in brakes is developed, based on the statistical nature of friction. The conditions under which an incipient vibration can develop are shown to be (i), 4 bm > a2L2 where b = elastic constant of the lining in shear, m = mass per unit area, a = change in coefficient of friction with speed, and L = load force per unit area; and also, (ii), a < 0.

Whether noise will result from the vibration depends on how close the natural frequency of the lining, (4 bm – a2L2)1/2/(4πm), is to a frequency of the drum which can be excited by resonance.

Observations on the relative noisiness of four kinds of lining were correlated with measurements of a and b. When the linings are ranked in order of increasing tendency to noise as predicted by the theory, it is found that the order is the same as that observed in brake tests on road cars.
Some Methods for the Structural Design of Wings for Application Either at Ambient or Elevated Temperatures
Authors: Semonian J. W. , Crawford R. F.
Published: January 2022

Some new methods are established for the design of aircraft-wing structures. The methods apply either at ambient or moderately elevated temperatures. Designs of a variety of structural configurations based on these methods are compared and discussed.
Design of Multivariable Optimum Filters
Authors: Westcott J. H.
Published: January 2022

The paper considers in detail a case of multivariable optimum filter design which is of engineering interest. This is the problem of extracting the best resemblance, in a minimum mean-square-error sense, of a message available in differently corrupted forms from a number of sources, given the statistical characteristics of message and disturbances. The solution is shown to involve an essential difference from the familiar case for a single source. Other multivariable optimum studies are not in principle different from the one considered here and consequently require the same type of analysis. A numerical example of the design of the optimum combination of filters for deriving a message from two noisy sources is given.
Performance Prediction for a Process Heat-and-Power Complex by Resistance Concept
Authors: Kayan C. F.
Published: January 2022

In process-plant engineering, systems of process-fluid heating combined with power generation are often of such complex character that orthodox analytical methods of mathematical, graphical, and numerical nature prove inadequate. In general, solution of thermal-energy flow processes, particularly under off-design conditions, is fraught with many complications; under these circumstances, recourse to analysis via the resistance concept of energy flow, offers distinct advantages. Furthermore, in terms of the concept which expresses flow as the result of a motivating force acting against resistance, processes may be simulated analytically by electrical flow with its attendant circuitry; that is, by electrical analogy.

In the heat-and-power process plant treated, a prime mover, such as a steam turbine, exhausts directly to a vapor-condensing fluid heater, thus serving, in effect, as a power-producing “reducing valve.” In such an arrangement, the performance of the turbine, as to steam consumption and corresponding steam exhaust, is greatly influenced by the heater conditions; conversely, the heater performance is directly dependent on the associated steam-turbine performance. The prediction of over-all performance characteristics of such an integrated complex is one in which the resistance concept is of unique value. Adaptation to simulation via electrical analogy thus introduces another tool for the study of combined process-and-power systems, the demonstration of which is the particular purpose of the present paper.
A Study of Heat Transfer and Pressure Drop Under Conditions of Laminar Flow in the Shell Side of Cross-Baffled Heat Exchangers
Authors: Test F. L.
Published: January 2022

This paper discusses a study of the laminar region and develops heat-transfer and pressure-drop correlations for an effective Reynolds number below 100. The principal variables were oil-weight rate, mean oil temperature, mean water temperature, and baffle spacing. All runs were performed with an SAE 60 and an SAE 30 oil. An increase in baffle spacing would increase the rate of heat transfer and decrease the pressure drop, particularly at low oil flows. A change in the mean oil temperature had very little effect on the oil-film coefficient of the SAE 60 oil. The oil-film coefficient would change very rapidly with mean water temperature. The heat-transfer and pressure drop results are correlated on the basis of an effective Reynolds number. The effective Reynolds number is a function of the effective area which accounts for various leakage passages. The correlations predict results that rarely differ by more than 10 per cent from the experimental results.
Dynamic Response of Heat Exchangers Having Internal Heat Sources—Part I
Authors: Clark J. A. , Arpaci V. S. , Treadwell K. M.
Published: January 2022

Dynamic response of the bulk temperature of the coolant in a heat exchanger having time-variant heat sources is evaluated analytically as a function of space and time. The mathematical development involves the use of the Laplace-transform technique. Results of the theory are compared with experiment and favorable agreement is obtained. Both theoretical and experimental results are included. Heat exchangers to which the solutions apply include the heterogeneous nuclear reactor.
Heat-Transfer Rates to Cross-Flowing Mercury in a Staggered Tube Bank—II
Authors: Rickard C. L. , Dwyer O. E. , Dropkin D.
Published: January 2022

As part of a continuing liquid-metal heat-transfer program at the Brookhaven National Laboratory, both local and tube-average heat-transfer coefficients have been obtained for the flow of mercury normal to a staggered tube bank. The bank consisted of sixty ½-in. tubes, six wide and ten deep, arranged in an equilateral-triangular array. The paper presents results showing the effects of flow rate, Prandtl number, wetting, gas entrainment, and tube location on the tube-average coefficients. The angular variation of the local coefficient is not considered here, owing to the fact that the values have not been calculated completely from the original data. The mercury results are compared with a few results obtained with water in the same equipment. The heat-transfer runs cover the Reynolds number range of 20,000 to 200,000, whereas the water runs cover the range 8000 to 20,000. Pressure-drop results for both water and mercury flow through the tube bank are reported also. The mercury coefficients for tubes in the interior of the tube bank are well represented by the equationNu=4.03+0.228(Pe)0.67
Heat Transfer to Fluids With Low Prandtl Numbers for Flow Across Plates and Cylinders of Various Cross Section
Authors: Grosh R. J. , Cess R. D.
Published: January 2022

Local and over-all heat-transfer coefficients were determined analytically for one and two-dimensional flow of a fluid with small Prandtl number, such as a liquid metal, across a flat plate and cylinders of various cross section. The possibility of heat generation within the fluid was considered. Certain of the results were simplified for convenient calculation, and the approximations investigated. A comparison of the results with those of Pohlhausen and Squire showed good agreement. The procedure for obtaining these coefficients rested upon a consideration of forced convection in a fluid with small Prandtl number which implied that inviscid flow can be assumed, and eddy transport of heat is negligible in comparison to molecular conduction for flows with small or moderate Peclet numbers. The analysis was simplified greatly by means of a transformation and certain results due to Boussinesq (1). The agreement of the analytical results with those obtained experimentally by Hoe (2) for mercury flowing through tube banks and the method for calculating heat-transfer rates in tube banks will be described in a later paper.
Heat Transfer to Flow in a Round Tube With Arbitrary Velocity Distribution
Authors: Whiteman I. R. , Drake W. B.
Published: January 2022

An extension of the classical Graetz problem is presented to cover various velocity profiles; and the variation of Nusselt modulus with respect to these profiles is shown.
Boundary Layer Along Annular Walls in a Swirling Flow
Authors: Yeh Hsuan
Published: January 2022

The development of incompressible turbulent boundary layers along concave and convex stationary annular walls is investigated analytically and experimentally for a swirling flow; i.e., flow with both tangential and axial mean velocities. It was found that the integral momentum equation describing this type of boundary layer contains three correction terms to the conventional equation. The combined influence of these corrections appears to promote the growth of the boundary layer next to a concave wall. Other differences between the boundary layers with swirl and those without swirl are pointed out and interpreted. Measurements on turbulence intensities appear to confirm such interpretations.
Interpreting Dynamic Measurements of Physical Systems: Part I—Aims and Objectives
Authors: Lees Sidney
Published: January 2022

Background concepts are developed for the interpretation of dynamic measurements. General objectives for a dynamic-measurements program are discussed together with suggested criteria for selecting a test method. A generalized concept of the linear system is developed that has its quantitative form in the idea of the multicoupled operating system with several inputs and outputs. Several schemes to represent the parameters and coefficients of the performance equations associated with the multicoupled operating system are given, according to the test procedure. A general discussion is included of the experimental limitations bounding the interpretation techniques.
Resistance to Rolling and Sliding
Authors: Dunk A. C. , Hall A. S.
Published: January 2022

In general a single “coefficient of friction” is inadequate to define the fractional resistance between contacting bodies. It is necessary to know both the inclination of the resultant force line and the offset of this line from the theoretical point of contact. This paper presents results of experiments, which were made to determine the effects of velocity on the inclination, and the offset of the line of action of the resultant force between two disks in peripheral contact.

The results indicate that the sliding velocity is of primary importance in determining the inclination of the line of action of the resultant force. It is the sum of the sweep velocities that is of primary importance in determining the offset of the resultant force line. The nature of the relationship between the angle of inclination and the offset of the line of action of the resultant force, and the proximity of the contact conditions to those existing for pure rolling, was investigated but no conclusive results were obtained.
General Design Considerations for Smaller Gas Turbines
Authors: Von Der Nuell W. T.
Published: January 2022

Following the general acceptance of its big brother, the smaller gas turbine is entering the market as a strong contender among power producers. While many thousands of units in the range up to 500 hp are in daily use, especially in the Armed Forces, new developments are active on a large scale with the biggest financial input probably aiming at vehicle propulsion. Due to the flexibility in arrangement and working the smaller gas turbine can find application in numerous fields where its outstanding capabilities offer definite advantages. Recent developments have demonstrated that its fuel consumption need not be too high and that it can be a very reliable machine. For further improvements, the most important contributions can be expected through better heat exchangers and better materials in addition to the continued efforts to raise component performance and to develop greater adaptability, such as reversibility.
Ideal Performance of Valved-Combustors and Applicability to Several Engine Types
Authors: Goldstein Arthur W. , Klapproth J. F. , Hartmann Melvin J.
Published: January 2022

Pressure rise and flow capacity of valved combustors are estimated, and engine power and efficiency are calculated using valved-combustor characteristics with and without regenerators for stationary power turbines and for turbojet and ramjet engines. Results are compared with those from similar engines using unvalved combustors.
Advancing Adhesion—Development and Test of a Chemical Formulation to Condition the Running Surface of Rail for Improved Wheel-to-Rail Adhesion
Authors: Fisher F. G. , Allen R. K. , Luvisi G. W.
Published: January 2022

Chemical conditioning of rail running surface to overcome the effects of oil films is capable of producing a definite increase in locomotive adhesion. Extensive tests under operating conditions for more than a year have demonstrated its practicability and economy. Characteristics necessary to permit a chemical formulation to qualify for commercial use have been determined and a practical method of application developed. The ultimate objective of application from the locomotive, as is done with sand, is being sought.
A Method for Studying the Behavior of Cutting Fluids in Wear of Tool Materials
Authors: Colwell L. V.
Published: January 2022

Refinements of design and instrumentation in a new friction and wear machine result in some new types of information which show promise of extending knowledge of the mechanisms of friction, lubrication, and wear. Provision has been made for varying normal load linearly with time and oscillating it between preset values. There is continuous recording of both the normal load and the friction reaction. Continuous recording at oscillating normal loads has discriminated sharply between lubricant additives. Close control of test conditions in wear studies has made it possible to identify high residual compressive stresses produced in finish grinding of cutting tools.
The Pressure-Viscosity Effect: Background
Authors: Hartung H. A.
Published: January 2022

Indications are that the pressure-viscosity effect is an important factor in certain cases of lubrication, notably heavily-loaded elements. How important it is in the lubrication of lightly-loaded elements we do not know, nor do we know what refinements in design may be possible by taking this factor into account. The three papers which follow this introduction are modern contributions to our knowledge in this area. Following them, the Research Proposal on the Machine Element Test program will be discussed. Hopefully, the result of this presentation and discussion will be a better understanding of the importance of this problem and the potential value to industry of a solution to it.
Viscosity-Pressure Effect on Friction and Temperature in a Journal Bearing
Authors: Needs S. J.
Published: January 2022

The recently published report on investigations conducted by the ASME Research Committee on Lubrication on the increase in viscosity of lubricants with pressure brings up the question of the importance of this phenomenon in actual machine elements. The present tests were undertaken to show differences in friction and operating temperature when heavily loaded partial journal bearings were operated with two different oils in the same viscosity range but of widely different viscosity index and viscosity-pressure characteristics. It is hoped that the results obtained in this short study will lead to more comprehensive investigations, not only in the field of journal bearings, but in other machine elements as well.
Symposium on Welded Spiral Cases from the Consulting Engineers’ and Users’ Viewpoint: Hydraulic and Weight Features of Welded Spiral Cases
Authors: Sutherland R. A.
Published: January 2022

An illustrative example of comparative head loss of welded and riveted plate-steel spiral cases shows that a substantial monetary value may accrue by the use of a welded case. An approximate relationship for weight of case in terms of rated head, case-design head, and inlet diameter is derived and checked against known data.
Controlled Starting and Loading of Modern Central Power Stations
Authors: Kuehn F. W.
Published: January 2022

The paper outlines experiences in starting major central-station equipment of all vintages under controlled conditions, with emphasis on a new 160-mw, 1250-lb, 950-F, single-shell tandem-compound turbine. The influence of steam leads between turbine and boiler on turbine end steam temperatures; quenching of valve bowls; and relation between horizontal turbine-flange temperature differentials and permissible loading rates are explained in detail. Use of steam from the first turbine stage for heating massive horizontal flange sections in the first to seventh-stage region of the high-pressure turbine as an operating routine, over a two-year period, to reduce loading time for starts from cold and after weekend shutdown, and to minimize flange distortion, is discussed. Boiler-drum circulation difficulties and remedies, and some innovations in furnace tube-metal temperature measurements are covered.
Study of Corrosion and Cavitation-Erosion Damage
Authors: Lichtman J. Z. , Kallas D. H. , Chatten C. K. , Cochran E. P.
Published: January 2022

The effects of fluid cavitation and cavitation bubble collapse on a guiding surface have been investigated using two water tunnels, a magnetostrictive-transducer apparatus, a piezoelectric transducer apparatus, and a rotating-disk apparatus. Studies of the mechanism of damage to a surface and its relationship to change in fluid pressure and stream velocity were made. These studies and examination of numerous ships in service showed that although fluid cavitation may occur adjacent to underwater appendages of vessels at normal operating speeds, the areas in which cavity collapse is the primary cause of damage are restricted to propellers. Damage to ships’ struts, rudders, and other appendages is shown to be primarily corrosive in nature, aggravated by mechanical scouring action.
Subcritical and Critical Flow Through Straight-Through, Elbow, and Tee A-N Fittings and Sharp-Edged Orifices at Elevated Temperatures
Authors: Ducoffe A. L. , Bennett J. R. , Ray C. G.
Published: January 2022

This paper presents the results of an investigation of the flow through straight-through, elbow, and tee A-N standard fittings at negligible approach velocity with approach temperatures up to 1100 F and head pressures up to 60 psia. The element pressure ratio, i.e., the ratio of downstream to upstream static pressure across the test element, was varied between 1.0 and approximately 0.25. Empirical equations for the subcritical and critical flow regimes are derived for the rate of weight flow as a function of element pressure ratio, flow area, and approach temperature and pressure. Empirical equations for a given geometry are derived for a flow factor which is shown to be a function of pressure ratio only in both the subcritical and critical regions. In addition, previous work at room temperature on the flow through sharp-edged orifices in the subcritical and critical regimes has been extended to include a variation of approach temperature up to 1100 F.
A Method for Predicting Supercompressibility Factors of Natural Gases
Authors: Zimmerman R. H. , Beitler S. R. , Darrow R. G.
Published: January 2022

Accurate prediction of the supercompressibility factor for natural gases is of great importance to the natural-gas industry. This paper presents a working method for the accurate prediction of these factors within the pressure range of 0 to 3000 psi and in terms of gas properties generally known or conveniently determined. This method is the basis upon which the American Gas Association Supercompressibility Tables have been developed.
Comparison of Total Emittances With Values Computed From Spectral Measurements
Authors: Bevans J. T. , Gier J. T. , Dunkle R. V.
Published: January 2022

Spectral and total emittances have been measured for materials exposed to various oxidation conditions (total of 25 samples). The total emittance values computed from the spectral data have been found to compare favorably with the measured total values. The experimental techniques utilized for both types of determinations are described and the effect of temperature, sample preparation, and experimental errors are discussed relative to the differences obtained in the results.
On-Off Control With Periodic Sensing Device
Authors: Izawa Keisuke
Published: January 2022

The paper describes the effectiveness of PD-type control function for the on-off control system with a periodic sensing device. When the system is subject to steady random disturbance, provided that the disturbance is varying rather slowly compared to the time constant of the controlled plant, the properly chosen PD control action can effectively decrease magnitude of fluctuation of the controlled variable.
Investigation of Erosion and Corrosion of Turbine Materials in Wet Oxygenated Steam
Authors: Cataldi H. A. , Cheng C. F. , Musick V. S.
Published: January 2022

Steam from the boiling water reactor of the Dresden Nuclear Power Station will enter the turbine at 869 psia and 525 F with ½ per cent moisture and with oxygen concentration higher than normal in power-plant practice. This paper discusses a series of preliminary laboratory tests evaluating the resistance of various materials for turbines and related components to erosion (impact, washing, wire-drawing) and corrosion (weight loss, pitting depths, crevice, and galvanic attack) in wet, oxygenated steam. Materials tested included carbon and low-alloy steels and cast iron, austenitic and ferritic stainless steels, Monel, cupronickels, leaded bronze, Stellite, and Ductile Ni-Resist No. 3. It is concluded that, with proper design, conventional materials may be used in the Dresden turbine except in a few critical areas.
One-Way Surge Tanks for Pumping Plants
Authors: Parmakian John
Published: January 2022

One-way low-level surge tanks may be used for the control of water hammer at pumping plants where water-column separation occurs in the discharge line subsequent to a power failure at the pump motors. This paper describes the characteristics of these tanks and also includes a typical graphical water-hammer solution of the problem.
Aluminum in Rolling Stock; Impact Tests at Collision Speeds
Authors: Campbell R. A. , Sutherland J. G. , Whiting J. F. , Kemp R. A.
Published: January 2022

The impact tests at collision speeds reported in this paper demonstrate that aluminum has high impact resistance. The tests also prove that the welded aluminum center sill met the published design requirements of the AAR. Moreover, valuable data were obtained on body-to-sill connections and on the performance of draft gear and rear draft lugs. The information gained from these tests already has been incorporated in the design of 30 welded aluminum hopper cars built for the R. & S. Railway in 1957 as well as the 17 covered welded aluminum hopper cars now on order for Aljam and the 5 all-aluminum refrigerator cars now on order for the Canadian National Railways.
Dynamic Characteristics of Cam Forms Calculated by the Digital Computer
Authors: Mercer S. , Holowenko A. R.
Published: January 2022

This paper presents a simple, numerical method for analyzing the residual vibrational-stress characteristics of any cam form for which the cam-acceleration function is known. This may be regarded as a generalization of prior work, because the use of a high-speed digital computer in conjunction with this method makes it possible to analyze those cams which otherwise would be impractical to consider. Results in the form of residual stress-factor curves plotted against follower-system natural frequency are given for fifteen different cam forms. In addition, a relation between the residual vibratory-stress amplitude and the resonant build-up of stress for various follower-system natural frequencies is shown. As a result, it is possible to use the residual-stress-factor curve to determine the frequencies at which resonance is likely to be troublesome, and the strength of the resonant tendency at each critical frequency for a cam with dwells of any duration.
On the Art of Designing Compressor Foundations
Authors: Swiger W. F.
Published: January 2022

The designer of foundations for vibrating machines, such as compressors, must consider several related fields. The behavior of soil under static and vibrational loads and the magnitude and effects of soil distortions must be evaluated. Means of limiting vibration and the possibilities of deterioration or distortion of the actual foundation must be considered. This paper summarizes the relationship of present thinking and recent studies in the various fields to compressor foundations.
Slipper Bearings and Vibration Control in Small Gas Turbines
Authors: Hill H. C.
Published: January 2022

Several new principles of bearing design have proved effective in improving the reliability and smoothness of small gas turbines. The key development was the tilting-slipper thrust bearing which not only provided important radial clearance, but also made possible higher speeds at higher thrust loads. One of the unique features considered important for performance and low production costs is that the slippers float in their retainers instead of having fixed pivots.
Rearrangement of the Temperature Field in Flow Around a Bend
Authors: Eckert E. R. G. , Irvine T. F.
Published: January 2022

Measurements of the temperature and velocity field are reported for a specific duct geometry which bends the flow by 90 deg and simultaneously accelerates it to an average exit velocity which is twice the inlet velocity. The measurements demonstrate that the temperature field existing in a cross section upstream of the bend is considerably rearranged by the action of the secondary flow. The temperature field also influences the velocity field as observed in the exit cross section. A simple calculation method which allows a prediction of these effects in the core of the flow field is presented and good agreement to the results of the measurements is found. The importance of this flow rearrangement to various engineering applications, especially to the design of gas turbines, is discussed.
Present State and Future Outlook of the Free-Piston Engine
Authors: Huber R.
Published: January 2022

The first part of the paper gives a short description of the gasifier, type GS-34 gasifier, with diagrams showing the main operational factors versus gas pressure and stroke length. The present state of its application to ships, stationary plants, and locomotives is reviewed briefly. Details are given when running with a reduced number of gasifiers in service in a stationary power plant of 6000 kw (Cherbourg). In the second part the trend of future development is examined, especially with regard to an increase in power output per gasifier. The possibilities and limits of supercharging and after-burning are studied, as well as twinning of the gas-generators and increase of their size. The general relationship for similar engines but of different sizes is given. A gasifier with a 20-in. diesel bore is studied. Such an engine, supercharged, twinned, and with after-burning would produce 8000 to 10,000 hp on the turbine shaft per unit.
Time Domain Synthesis of Sampled-Data Control Systems
Authors: Jury E. I. , Semelka F. W.
Published: January 2022

This paper deals with the application of the modified z-transform to synthesis of sampled-data control systems. The applicability of the modified z-transform as an analysis tool has been demonstrated in recent publications. Currently, this transform method is being developed to reduce the process of synthesis of both sampled-data and continuous systems to systematic, straightforward numerical processes. In several recent papers [1, 2, 3] the z-transform has been applied to synthesis of sampled-data systems in both time and frequency domain methods. From these papers and their discussions, the need for the refinement in synthesis to include the continuous response characteristics is apparent. The synthesis procedure presented is a time domain technique which permits the designer to achieve control of the continuous behavior of the system. The desired characteristics are specified in terms of standard synthesis criteria, and from such specifications the required compensation transfer functions are determined.
Reinforced Concrete Barrier Modeling In-Series Impacts in LS-DYNA
Authors: Sharma Roshan , Silvestri Dobrovolny Chiara , Hurlebaus Stefan , Kiani Maysam
Published: January 2022

The design of longitudinal barriers using reinforced concrete is typical in roadside safety design. Roadside safety hardware such as bridge rails, median barriers, and transitions are designed to safely contain and redirect impacting vehicles without imposing any significant risks to the occupants. As full-scale crash tests of new designs are expensive and time-consuming, finite element modeling and simulation of the impact event is often involved. In LS-DYNA, one of the most popular software in roadside design, there are multiple material models for concrete modeling and there is no specific guideline on the selection of the concrete material model. This paper evaluates the behavior of material models MAT_CSCM_CONCRETE and MAT_RHT during the study of truck platoon implications. The concrete erosion, deflection, and failure mechanism of two consecutive tractor-van trailer impacts into the barrier FEA models were analyzed to select a representative material model for further study.
Tunable Enhanced Vibration Energy Harvester As a Power Module for Portable Electronics and IoT Sensors
Authors: Nguyen Hieu , Bardaweel Hamzeh
Published: January 2022

This article presents a novel, low-frequency, tunable, and wearable power module that can power portable electronic devices by harvesting power from human body motion. The device features a unique spring system that allows the power module to harvest at low-frequency range; ideal for integrating into daily human activities. The unique design of the power module allows for low-frequency specialization, i.e., less than 5 Hz. The spring system can be tuned into one of two modes. The optimum load resistance is determined to be 96 Ω. When shaken by hand and connected to a smartphone, the power module outputs a power of approximately 35 mW. The power module is handheld and has a small volume of roughly 3.8 × 7.6 × 17.8 cm3. An internal power management circuitry that can convert the AC output voltage from the harvester into a DC voltage is built and tested experimentally. In this work, the ability of the power module to utilize vibrations from human body motion in charging a smartphone is demonstrated.
Simulation of Spatters Sticking Phenomenon in Laser Powder Bed Fusion Process Using the Smoothed Particle Hydrodynamics Method
Authors: Meng Lingbin , Sun Tao , Dube Tejesh , Sagar Sugrim , Yang Xuehui , Zhang Jian , Zhang Jing
Published: January 2022

In this work, a smoothed particle hydrodynamics (SPH) method is developed to simulate the spattering phenomenon in the laser powder bed fusion (L-PBF) process. First, an experiment using the high-speed synchrotron X-ray full-field imaging is conducted to acquire in-situ images during the L-PBF process. Then, a scenario is selected from the X-ray image as a case study of the SPH model. In the case study, a particle is ejected and melted by the metal vapor, impacts with another particle, solidifies, and sticks to the other particle to form a rigid body. As a result, the trajectories of the two particles match well with the experimental observation. The evolution of velocity and temperature of the particle is extracted from the simulation for analysis. The SPH model can be a useful alternative to computational models of simulating the spattering phenomenon of L-PBF.
Design and Construction of a Spherical Mobile Robot Prototype for Monitoring Oil Palm Plantations
Authors: Roa Prada Sebastián
Published: January 2022

Colombia is the biggest producer of palm oil in Latin America. The production of palm oil alone makes up for 6% of the agricultural gross domestic product of the country. However, growing oil palm trees is a risky business since this kind of tree only starts producing its fruits when it reaches the age of three years, and during that time the trees are very prone to contract several diseases, which may completely damage the tree. The most common, and devastating, disease that can affect oil palm trees is the bud rot disease, which destroys the young tissue of the palms. Experts indicate that when the disease is detected in its early stages, a simple pruning of the affected area together with a chemical control may be enough to fight the disease. Therefore, there is a strong need for continuous monitoring of the trees. Some of the main challenges for the monitoring of oil palm plantations are the large areas that must be covered, the difficult environmental conditions with high temperatures and relative humidity, and the irregularities of the terrain. One way to make this monitoring task more cost effective, as compared to doing it only by means of human workers, is with the assistance of mobile robots. There are different kinds of mobile robots that have been used in precision agriculture applications such as tracked robots and wheeled robots. Although these robots offer several advantages such as simple mechanics and good payload capacities, in many cases they may not be the best choice, for example in very uneven or muddy terrain.

This work proposes the study, design and construction of a spherical robot, intended for remote monitoring of oil palm plantations. Spherical robots provide an interesting alternative for monitoring of plantations thanks to their excellent maneuverability and adaptability to various terrain conditions. Spherical robots can rotate in place to change direction, can move over muddy terrain and they can even float and move over water. They also have some disadvantages such as difficulties to pass over an obstacle and lower payload capacity.

This work was carried out in 4 stages, the first one was the selection of a locomotion architecture that adapts to the proposed design conditions. Then, the mathematical model of the robot was obtained, which allowed simulating the dynamic behavior of the robot and designing a control system to guarantee the stability needed for the guidance of the robot. Finally, the prototype was built and validated.