bluuebunny/crossref_metadata_2025 huggingface dataset:
A 7R-Based, Two Degrees of Freedom Robomech
Authors: Smaili Ahmad A.
Published: December 2020

A robomech is a crossbreed of a mechanism and a robot arm. It has a parallel architecture equipped with more than one end effector to accomplish tasks that require the coordination of many functions. Robomechs with multi degrees of freedom that are based on the 4R and 5R chains have found their way into the literature. This article presents a new, two-degree of freedom robomech whose architecture is based on the 7R chain. The robomech is capable of performing two-function tasks. The features, kinematic constraints, and synthesis procedure of the robomech are outlined and an application example is given.
Resolving Velocity-Degenerate Configurations (Singularities) of Redundant Manipulators
Authors: Podhorodeski Ron P. , Nokleby Scott B. , Wittchen Jonathan D.
Published: December 2020

A kinematically-(joint)-redundant spatial manipulator will not be velocity degenerate (singular) if any combination of six of its joints span the 6-system of general velocity. Therefore, all 6x6 sub-matrices of the matrix of joint screw coordinates J (commonly referred to as the Jacobian) must be rank deficient for a spatial joint-redundant manipulator to be velocity degenerate. Concurrency of zero 6x6 sub-matrix determinants of J allows sets of joint-displacement conditions leading to velocity-degenerate configurations to be identified. For actual manipulators, each set of degeneracy conditions must be checked to see if the conditions are feasible for existing device dimensions and occur within existing joint displacement limits. Within this work, the concept of concurrency of zero 6x6-sub-matrix determinants of J is considered and applied to the identification of velocity degeneracies for the Canadian Space Agency (CSA)/International Submarine Engineering (ISE) STEAR Testbed Manipulator (STM). The STM consists of two 7-jointed arms that are kinematically similar to the arms of the Special Purpose Dextrous Manipulator (SPDM) proposed for use on the International Space Station (ISS). Five unique 2-condition families of velocity degenerate configurations are found to cause velocity degeneracies for each of the 7-jointed arms. It is shown that only four of these five potential degeneracies correspond to reachable families of joint-displacement configurations for the CSA/ISE STM arms.
Design of Planar Miniaturized Mechanisms With Flexural Pivots
Authors: Schönherr Jürgen , Müglitz Jörg
Published: December 2020

The paper deals with synthesis, modeling and analysis of mechanisms with flexural pivots preferably used in micro-systems, measuring devices, or medical devices. Among other things, it will be shown that rotary joints can be replaced by flexural pivots so that the kinematic performance will be kept. Already in the phase of kinematic design, one has pay attention to material properties, load, and strain to ensure both the mobility and the strength of the mechanism. Using two examples, a Robert’s straight line generator and a trunk-like motion generating mechanism, it is shown here, how a relatively simple multi-body model can be used effectively for mechanism analysis and optimization.
Statically Balanced Compliant Mechanisms (SBCM’S): An Example and Prospects
Authors: Herder Just L. , van den Berg Fred P. A.
Published: December 2020

In some applications of compliant mechanisms, the fact that energy is stored in the elastic members presents a problem. For instance, in manually operated instruments, such as surgical forceps, the operating force should preferably be proportional to the gripping force, while forces introduced by the bending of elastic elements would disturb this force transmission process. To restore the force transmission quality, compliant mechanisms may be statically balanced, resulting in statically balanced compliant mechanisms (SBCM’s). This paper presents an example of a compliant surgical forceps mechanism, which is statically balanced by a low-friction rolling-link compensation mechanism. Force feedback is restored to the extent that the pulse in an artificial artery can be perceived clearly.
3-D Extension for MIT-MANUS: A Robot-Aided Neuro-Rehabilitation Workstation
Authors: Krebs Hermano I. , Buerger Stephen P. , Jugenheimer Kristin A. , Williams Dustin , Hogan Neville
Published: December 2020

An extension to an existing planar manipulator for robot-aided therapy is described. The MIT-MANUS rehabilitation workstation, shown to be effective in sensorimotor training of recovering stroke patients, is augmented by the addition of a module permitting movements in a 3-dimensional workspace. Key analyses in the mechanical design of the new module are described. A compact, screw-driven, low mechanical impedance module meets the target requirements. Manufacturing of this novel device will be followed shortly by its deployment in clinical trials.
Characterization of Dynamics in Special 6-6 PKMs
Authors: Shamblin Scott A. , Wiens Gloria J.
Published: December 2020

This paper presents a study on the contributions of the dynamics on the performance of a special 6-6 parallel kinematic mechanisms, with application to machine tools. Using Kane’s method, the dynamics equations of motion are derived with inclusion of the strut masses. Comparative observations are made using both workspace and sample trajectory based characterizations.
Improving Kinematic Characteristics of Geneva Mechanisms Using Variable Input Speed
Authors: Lee Jyh-Jone , Cho Chih-Chong , Chang Sun-Lai
Published: December 2020

A method is proposed to improve the kinematic characteristics of the conventional Geneva mechanism. Rather than driving the input crank at a uniform speed, suitably changing the crank speed can not only eliminate the impact loading at the beginning and end of the motion cycles but also reduce the wheel peak velocity and/or the peak acceleration values. In this paper, we investigate design criteria and formulation for the planning of such input crank motion. Examples for the input planning via the general Bezier’s curve model are then given to illustrate the procedure. With no need to alter the conventional structure, the result provides a simple and practical tool for designing an intermittent motion generating mechanism with excellent kinematic characteristics.
On the Application of Kinematic Units to the Topological Analysis of Geared Mechanisms
Authors: Liu Chia-Pin , Chen Dar-Zen
Published: December 2020

Based on the concept of kinematic fractionation, a systematic approach for the topological analysis of geared mechanisms is presented in this paper. It is shown that a geared kinematic chain (GKC) can be regarded as a combination of kinematic unit(s). By identifying the embedded kinematic units, kinematic insight in the GKC can be exposed. The disclosed information leads to a straightforward and promising approach to prevent inducing redundant links. This approach forms the basis of a by-inspection procedure to determine admissible assignments of the ground, input and output links in a GKC. Admissible assignments of the ground, input and output links of one degree-of-freedom 5 link GKCs are obtained as an illustrative example.
Compliant Mechanism Prototyping
Authors: Mortensen Clinton R. , Weight Brent L. , Howell Larry L. , Magleby Spencer P.
Published: December 2020

Flexible segments present challenges to prototyping compliant mechanisms. This paper discusses methods for prototyping compliant mechanisms, including use of 3-axis CNC milling, laser cutting, and wire EDM. Rapid prototyping methods and hybrid methods are also discussed. A method for machining living hinge prototypes with good fatigue life is also documented.
A Multi-Variable Approach to Determine the “Best” Gear Design
Authors: Houser Donald R. , Harianto Jonny , Chandrasekaran B. , Josephson John , Iyer Naresh
Published: December 2020

Gear design requires the designer to compromise many design variables in order to determine the best performance of a gear set. Unfortunately the designer has a multiplicity of goals including keeping both bending and pitting stresses under an allowable value, minimizing scoring, achieving minimum efficiency and trying to minimize noise. This latter response variable is rarely considered in the initial gear design. In this work, noise is considered to be one of the more important design considerations.

One approach to multi-variable gear design that has been tried is design optimization. Usually optimization techniques are limited in the number of variables that can be handled and with so many response variables, it is difficult to come up with an objective function that reflects the considerations of a real gear designer.

In this paper we present a simulation-based approach to gear design that allows the designer to essentially “run all of the cases”. The simulation accounts for the true load distribution of the gears when computing response variables. Also, such factors as manufacturing tolerances may be included in the simulation so that truly robust designs may be obtained. Rather than using an objective function approach, designs are analyzed with a dominance filter that assesses each response variable in a manner that results in the “best” design. After these “best” designs are found, an interactive viewer allows the selection of those designs that best meet the designer’s goals with regard to all design variables.

Several examples are presented in this paper. In each case, over 65,000 designs are evaluated and the dominance filter results in from 200 to 900 successful designs, depending on the tolerances that are applied. After sorting with the viewer the designer usually ends up with from 5 to 20 designs whose features may vary significantly, but have similar performances.
Theory and Programming of a Generic Gear Library
Authors: Häussler U.
Published: December 2020

This paper discusses an approach, which combines theoretical consideration and object oriented thoughts in order to make gear computing extentable.

A generalized calculus is investigated, which has no loss of geometrical information. Calculating the fundamental forms of the conjugated surface, the enveloped surface will have the same properties as the tool surface.

By using object oriented programming in a gear specific way, it is shown, that all programms for gear and tool design may have the same structure, and are based on the same virtual methods and classes.
The Instantaneous Friction Force for Relative Motion
Authors: Perumean Don W.
Published: December 2020

This paper derives the free-body diagram for involute spur gears. The principles of this derivation are applicable to any two bodies moving with relative motion having a sliding contact between them.

The derived free-body diagram shows that the equation for the instantaneous sliding friction force includes a term for the instantaneous percent sliding of the contact. This percent sliding term allows the equation for the instantaneous sliding friction force to express the influence of the exact relative motion that is taking place at the point of contact.

The instantaneous sliding friction force equation for any two bodies moving with relative motion will include a term for the instantaneous percent sliding of the contact when observed from a third reference plane considered at rest.

The derived friction force equation will require the instantaneous coefficient of sliding friction to be redefined for relative motion.
Tooth Surface Fatigue Strength of Normalized Steel Conical Involute Gears
Authors: Ohmachi Tatsuya , Iizuka Koji , Komatsubara Hidenori , Mitome Ken-ichi
Published: December 2020

The tooth surface fatigue strength of the conical involute gear is evaluated in this paper. Test gears are straight intersecting-axis conical gears. The material of the test gear is normalized steel. The power circulating testing machine is used in this experiment. The circulating torque is kept constant and the number of times of contact is 107. The tooth surface life is evaluated by the pitting area rate. The critical value of the circulating torque is found between 147 N·m and 157 N·m. For critical torque, the pitting area rate does not progress over 4%. The Hertzian contact stress of the test gear is calculated at the circulating torque. The contact stress should be evaluated in consideration of the wearing effects.
New Toothed Belt Matches Various Pulley-Profiles
Authors: Schaefer Frank H.
Published: December 2020

This paper examines the possibility of a new toothed belt construction to run in various pulley-types. The measurements from a laboratory dynamometer test stand show the belt life under special test conditions by use of HTD-, STPD- and RPP-pulleys, each with an angle of wrap of 180°. In case of locked center distance the increase of torque causes tooth climbing until belt jumping occurs. The pretension was brought into line with the torque each time the torque was increased and the jumping limit torque was determined. From literature it is expected that the results for the behavior of the HTD- and the RPP-pulley are similar. Another parameter to describe the quality of motion is the noise. Here sound power is a very effective descriptor of how noisy an object is. It was determined from sound intensity measurements for HTD- and STPD-pulleys. The ratio of the toothed belt drive used for the noise measurement was 0.63.
Full Sliding “Adhesive-Like” Contact of V-Belts
Authors: Gerbert Göran , Sorge Francesco
Published: December 2020

Analysis of power transmission in a belt drive consisting of e. g. two pulleys might be treated as a boundary value problem. Tight side tension FT, slack side tension FS and the wrap angle α are the three natural boundary conditions.

In the literature, theories are developed where seating and unseating as well as the power transmitting part of the contact are considered. The solutions presented so far don’t fulfil the boundary conditions properly, since a certain tension ratio FT/FS is associated with a certain contact angle and not an a priori specified one.

It appears that a new type of full sliding solution must be introduced to handle the boundary condition problem. During part of the contact there is almost no tension variation in spite of the full sliding conditions. The designation adhesive like solution is here introduced for that part. Conditions and character of the adhesive like solution are outlined in the paper.
Measurements of Forces Between a Synchronous Belt and a Pulley
Authors: Distner Martin , Johannesson Tomas
Published: December 2020

In modern belt profiles, power is transmitted by both normal forces and friction forces. To control the load distribution between a belt and a pulley, avoiding power circulation and local tooth load peaks, it is necessary to take into account both types of forces. An analytical model for the load distribution has previously been presented by the authors. This work also introduces the effective pitch difference, EPD, which is the actual pitch difference between a pulley and a loaded belt.

To examine these matters and verify the model, a series of 270 experiments was carried out in a two-pulley test rig. Parameters investigated are: torque, tension, belt speed, pitch difference and running time. All of the measurements were conducted under quasi-static conditions. The equipment used included a specially designed measurement pulley that can measure four different engagement forces.

Experiments show that belt speed within automotive application range has no effect on load distribution, apart from engagement and disengagement peaks. Tooth flank normal forces and land area friction forces often work against each other. Belts with dissimilar pitch difference give rise to great differences in load distributions. Even a short running time causes a redistribution of the friction forces, although their sum remains constant.

The results show that it is possible to tailor the load distribution by adjusting the EPD. This offers an opportunity to avoid power circulation and unnecessary high contact forces. Changing the EPD for the correct load distribution at each interaction is easily achieved by individual adjustment of the pulley radius.
Applications of Numerical Analysis of Hobbing to Hob Wear, Cutting Force and Gear Tooth Surface Topography
Authors: Ariura Yasutsune , Umezaki Yoji
Published: December 2020

A new analytical technique is developed to calculate the volume cut with every hob tooth, cutting forces and feed mark patterns. The results of calculation are compared with experimental data, resulting in their good agreements. The estimation of wear of each hob tooth, hobbing forces and errors in hobbing can be obtained by calculation using this analytical method.
Robotic Deburring of Precision Gears
Authors: Nanlawala Michael , Manesh Ali
Published: December 2020

Machining processes such as milling, drilling, turning, hobbing or gear teeth cutting create burrs on the edges of metal parts when the cutting tool pushes material over an edge, instead of cutting cleanly through the material. The size, shape and characteristics of the resulting burrs depend upon a number of process factors such as: tool material and its hardness, tool sharpness, tool geometry, cutting forces, ductility of the material being machined, speed and feed of the cutting tool, and depth of the cut. Except for the turning operation, a subsequent deburring operation is often required to remove the “loose” burrs and also to produce a chamfer to “break” or smooth the edges of the machined part.

Gears, in general are deburred manually or by simple mechanical equipment such as Redin™ Deburring Machine. Because of the complexity and/or specific chamfering requirements of aerospace gears, most of these gears have to be deburred manually. In general, manual deburring is a very labor intensive process. Poor quality resulting from inconsistent manual operation, health, safety and environmental related issues, and high turnover of operators incur indirect cost as well. The “Redin Deburring Machines”, however, lack the dexterity and the programmability, which are essential to meet the specific chamfering needs of usually complex shaped aerospace gears. Automating the deburring process can therefore result in significant cost reduction, improved productivity, and improved quality of deburred edges. Mainly because of these reasons, there has been industry wide demand to replace manual deburring by more efficient, reliable and safer automated deburring system.
Prediction of Automotive Gearboxes Dynamic Behavior: Part B — Numerical Simulations for the Determination of New Mechanical Design Trends
Authors: Bourdon Adeline , Yakhou Karim , Play Daniel
Published: December 2020

Prediction of automotive gearboxes dynamic behavior during design is made possible through the use of numerical models and virtual prototypes. But market pressures require a formalization of new mechanical design activities. The aim of the second part of these two companion papers is to exploit the results to highlight future trends in mechanical design.

Simulations performed with numerical models enable us to obtain a better understanding of the vibratory phenomena which appear in gearboxes. These models dissociate local effects, such as gear mesh phenomena, from “global” effects, due to the gearbox architecture and allow us to evaluate interactions between components. They are used for explaining some experimental observations, such as the large differences between the dynamic transmission error in “pullup position” — corresponding to an established speed or to an acceleration phase — and “pulldown position” — corresponding to a decreasing speed phase. Local gear mesh effects can not explain these large differences. They are also used for evaluating the influences of mechanical modifications to the bearing environment, on the dynamic transmission error. Then, the consequences of these results are applied to the design and optimization of new gearboxes.
New Evaluation Method on Gear Dynamics Using Continuous and Discrete Wavelet Transforms
Authors: Ohue Yuji , Yoshida Akira
Published: December 2020

The aim of this study is to propose a new evaluation method of gear dynamics using continuos and discrete wavelet transforms. The Wavelet Transform (WT) is a method for the time-frequency analysis of signals. In order to evaluate the difference in the gear dynamics due to the gear material, the dynamic characteristics of gear were measured using a power circulating gear testing machine. The gear dynamics were analyzed in a time-frequency domain by the continuos and discrete WTs. The new evaluation method using the WTs proposed in this paper was very useful compared with the conventional one to investigate the damping characteristic and the dynamic condition of the gear equipment.
Static and Dynamic Tooth Loading in Spur and Helical Geared Systems: Experiments and Code Validation
Authors: Baud Sébastien , Velex Philippe
Published: December 2020

The primary objective of this study is to validate a specific finite element code aimed at simulated dynamic tooth loading in geared rotor systems. Experiments have been conducted on a high-precision single stage spur and helical gear reducer with flexible shafts mounted on hydrostatic or hydrodynamic bearings. The numerical model is based on classical elements (shaft, lumped stiffnesses, ...) and on an original gear element which accounts for non-linear time-varying mesh stiffness, gear errors and tooth shape modifications. External and parametric excitations are derived from the instantaneous contact conditions between the mating flanks by using an iterative contact algorithm inserted in a time-step integration scheme.

In a first step, experimental and numerical results at low speeds are compared and it is demonstrated that the proposed tooth mesh interface model is valid. Comparisons are then extended to dynamic fillet stresses on both spur and helical gears between 50–6000 rpm on pinion shaft. Despite a localized problem in the case of spur gears with one particular bearing arrangement, the broad agreement between the experimental and numerical response curves proves that the model is representative of the dynamic behavior of geared systems.
Reducing Vibration on Gears by the Means of Damping Disks
Authors: Funk Wolfram , Gassner Oliver G.
Published: December 2020

In the past, the concepts involving secondary measures for the reduction of solid-borne noise emissions of gearings were for the most part aimed at reducing the noise emission rate of the toothed gears. Other secondary measures were not so much concerned with the gears themselves, but with other gearing components. A new approach, however, includes the use of rotating damping disks bolted to the toothed gears. The use of bolted components results in small shifts of the resonance frequencies, in nonlinear effects and finally in friction damping of vibration amplitudes due to energy dissipation. A mathematical model for calculating the damping behavior of rotating damping disks will be developed on the basis of the equations first used by Valanis [4] and will be verified by testing.
Gear Noise Diagnosis System for Automobile Transmission Using Artificial Intelligence: Improvement of Judgement Performance
Authors: Moriwaki Ichiro , Nishiyama Masahiko
Published: December 2020

Gear noise emitted from transmission units for automobiles should be evaluated by an expert of gear noise. Although on some production lines, quietness performance estimates from measured noise levels of the units, the estimation must be severe. There is no definite relationship between the measured noise levels and the evaluations by the experts. Therefore, for standing on the safe side, the estimation should be severe. As a result, such an automatic gear noise diagnosis system must yield transmission units with over-quality. The present study deals with a new gear noise diagnosis system to which an artificial intelligence is applied; i.e., a neural net is applied. The former evaluations by the new gear noise diagnosis system were quite good when the statistical property of the teacher signals from which the system learned was similar to that of population. This fact means many teacher signals are necessary on the practical use. The present paper describes a new method for digitizing the measured noise levels. This method provided good evaluations of the system even when the statistical property of the teacher signals were not similar to that of the population. In addition, a new method, “Moment Method” for determining the construction of the neural net was introduced instead of “Back Propagation Method”. The Moment. Method contributed to the improvement of the system judgements.
Analytical Procedure for Prediction of Radiated Noise From a Gear-Shaft-Plate System
Authors: Park Chan Il
Published: December 2020

In order to predict the gear noise, a simplified model of gear-shaft-housing system is studied. The gear is modeled as a single degree of freedom mass-spring-damper system. The shaft-housing system is modeled as a clamped circular plate connected with a beam. The moment components of the beam excited by the gear mesh force are considered in the calculation of the plate vibration and radiated noise. The displacements of the clamped circular plate due to the r-direction moment and θ-direction moment are analytically derived. Radiated noise from the plate is also derived using Rayleigh integral. Using the derived results, the numerical examples are given.
Development of Transmission and Transfer Gear With Locomotive Noise (Whine Noise)
Authors: Kawasaki Yoshiki , Karube Masahiko , Kubo Aizoh , Khargonkar B. S. , Rao N. K. , Manjrekar Vikas
Published: December 2020

Between 1990 and 1995, ISUZU (ISZ) automobiles RV lines, specifically Trooper with MUA Type Transfer (Fig.1), had problems with loud locomotive noise, also known as whine noise. In July 1992, HINDUSTAN MOTORS (HM) found the same problem with its 4X2 MSG Type Transmission (Fig.2).† At first, we looked to the gear precision and tooth contact pattern on both good and defective transfer units for the cause of the whine noise; unfortunately, after investigation, nothing was found. In total, we checked the involute helicoid, outer shape of shaft and all faces of gear and root of gear. Consequently, we found the whine noise was caused by the root running out of gear resulting in an imbalance in the face and the shape of shaft, causing each to run out. At the same time, we found that minimized the unbalance value will solve the whine noise issue. We used two test units (good and defective) to conduct the research and to resolve the whine noise problem.
A Wave Generator of New Concept for Flex Gear of Harmonic Drive With Pure Involute Tooth Gear Pairs
Authors: Maiti R. , Roy A. K.
Published: December 2020

A new wave generator (or cam) is proposed (Maiti, Patent 1995) to drive the flex gear of strain wave gearing i.e., harmonic drives with gear pairs of pure involute profiles. The cam profile is made of circular arcs at the two contact zones and shifted elliptical curves for the other zones. The geometric constniction is made in such a way that tip interference is properly avoided for both engagement and disengagement with nominally stubbed or full depth involute gears. The theories are established to verify other geometric and gearing conditions. Evidently, in the existing products (all are patented design) the profiles are non-involute and none of them offers ideal gear kinematics. It is expected that this new harmonic drive will offer the best gearing kinematics and will have desired accurate performance.
On the Linear Line Complex and Hyperboloidal Gearing
Authors: Dooner David B.
Published: December 2020

The concept of a line complex is introduced and then a brief discussion of a linear line complex is given. A linear line complex can be very useful in specifying the spiral angle in hyperboloidal gearing. Ball’s reciprocity condition is used in conjunction with the linear line complex to specify the spiral angle using a system of cylindroidal coordinates. This spiral angle is such that the gear ratio is independent of the pressure angle.
Detection of Machine and Structure Assemblies With Bolt Looseness
Authors: Yeh J. H. , Liou F. W.
Published: December 2020

Machine and structural safety and reliability are important issues in engineering. Since self-looseness is one of the most frequent causes of failure in bolted joint structures, it is highly desirable to detect bolted joint looseness early. The focus of this study is to model the structure natural frequency variation as the bolted joint is loosened. A virtual spring approach, incorporating finite element analysis, is proposed to model bolted structure assemblies. The spring constant estimation based on the Hertz theory is addressed, and the relationship between the spring constant and structure natural frequency is presented. An experimental study is used to verify the analytical model. A load bolt is used to measure the existing force in a bolted joint. The changes in the natural frequency of fixed-fixed beams due to the presence of joint looseness were investigated both analytically and experimentally.
Design and Analysis of a Fuze-Configurable Trajectory Correction Device for an Artillery Projectile
Authors: Hollis Michael S. L. , Brandon Fred J.
Published: December 2020

With the advances in microelectronics, sensor technology, and packaging design, the reality of an artillery projectile, range correction device is conceivable. A previous report entitled “Preliminary Design of a Range Correction Module for an Artillery Shell” (Hollis 1996) demonstrated a possible concept called the D-ring range correction device. One of the main objectives of the range correction device concept was to contain all the mechanical and electrical components within a fuze-like envelope, while maintaining certain constraints that would allow the fuze to fit into a variety of artillery shells used by North Atlantic Treaty Organization (NATO) countries. Another objective of the range correction device concept was to avoid any changes within the ogive of any of the projectiles in the existing stockpile.

Range correction is achieved by a mechanism that symmetrically deploys four D-shaped blades, or drag blades, with the sole purpose of increasing drag. Estimates have been made of the percent change in drag as related to increases in frontal area. The deployed D-rings, with a spread of 80 mm, will increase the frontal area by 1.63 times. If the D-rings are extended a centimeter farther to a deployment diameter of 100 mm, the increase in frontal area is 2.39 times. An initial study by Brandon and Jara has indicated that reasonable maneuver authorities can be achieved for frontal areas of 7.3 in2 (47.1 cm2) and 10.7 in2 (69.0 cm2), which corresponds, respectively, to the 80-mm and 100-mm deployment diameters.

This report is a culmination of many design iterations, numerical analyses, shock tests, and actual cannon launchings. Most of the design iterations and numerical analyses are not mentioned in this report simply because they were stepping stones that led to the final design. Structural analyses indicate that the overall prototype design is durable enough to withstand the most severe artillery cannon launching available today. The design should be capable of withstanding 15,000 g’s of inertial set-back loads with 150,000 rad/s2 of angular acceleration. In addition, the design is also capable of deploying at a velocity of 650 m/s, while spinning at 250 cycles per second. The next step would be to fabricate the design in order to truly verify the integrity of the structure and to determine the overall effect of the deployed drag blades on the range of flight.
Parabolic Log-Log Fatigue Life Model
Authors: Savage M.
Published: December 2020

A rapid method for determining service fatigue strength data is to test the product or device at an elevated load. Load-life relationships for engineering materials normally show a large reduction in life for a small increase in load. Unfortunately, there is little agreement on the exact nature of this load-life relationship. Some sources show a linear semi-log relationship. Some show a single linear log-log relationship. And some show a two-line log-log relationship with the shallower slope line active after ten-million load cycles or more. The two-line relationship agrees more closely with expected behavior. It predicts a difference between the load-life characteristics in the field at moderate service loads and the load-life characteristics in the laboratory with high test loads. However, the determination of the location and slope of the second, shallow, high-life line is an expensive proposition. In this paper, a parabolic log-log load-life model which predicts a gradual transition from the short-life testing environment to the long-life use environment is presented and compared to the two linear models. Fitting the model to test data is described as is the use of the model in planning tests for failure prevention prediction.
A Fuzzy System for Train Driver Support Towards an Efficient Handling of Engine Malfunctions
Authors: Drakatou S. , Karakassis K. , Dentsoras A.
Published: December 2020

In the present paper, an approach based on fuzzy logic is presented concerning a fuzzy decision support system for faults’ handling in train driving. A short introduction is given first that contains the problem’s description and its major aspects. A literature review follows that refers to the last advances in the field of man–machine interface, fuzzy logic applications and fault handling procedures in train driving. The paper emphasizes also on the important role of fuzzy logic in capturing, expressing and exploiting the existing experience on faults’ manipulation during train operation.

Furthermore, a theoretical approach is proposed for the development of a fuzzy decision support system that advises the train operator on faults’ handling during its operation. Except of the advice that could offer, it is expected that — after its development — the system will be able to continuously check on-line the operator’s actions and operations in order to conclude, in a fuzzy manner, about both their correctness and efficiency and to suggest further actions and operations to be undertaken.
Scenario-Based FMEA: A Life Cycle Cost Perspective
Authors: Kmenta Steven , Ishii Kosuke
Published: December 2020

Failure Modes and Effects Analysis (FMEA) is a method to identify and prioritize potential failures of a product or process. The traditional FMEA uses three factors, Occurrence, Severity, and Detection, to determine the Risk Priority Number (RPN). This paper addresses two major problems with the conventional FMEA approach: 1) The Detection index does not accurately measure contribution to risk, and 2) The RPN is an inconsistent risk-prioritization technique.

The authors recommend two deployment strategies to address these shortcomings: 1) Organize the FMEA around failure scenarios rather than failure modes, and 2) Evaluate risk using probability and cost. The proposed approach uses consistent and meaningful risk evaluation criteria to facilitate life cost-based decisions.
Vibrational Characteristics of Tapered Roller Bearing Cages
Authors: Karloff J. A. , Weins W. N. , Arnold R. C.
Published: December 2020

One of the important components of a tapered roller bearing is the cage. The main function of the cage during operation is to maintain roller spacing. Although being one of the more complicated parts of a tapered roller bearing, historically, very little specific engineering has been published to provide a design basis for the tapered roller bearing cage. This work analyzed specifically, the cages from tapered roller bearings as used in the railway industry.

As the load carrying requirements for railcars have increased, the size of bearing has also increased. Although cage dimensions have increased with bearing size, little specific engineering has been published to document the effect the change in size has on the durability of the larger cages. Testing was conducted to determine the amount of stress induced on the cage due to the vibration environment of a tapered roller bearing used in rail service. Cages evaluated were steel cages from 6 ½ × 12 and 7 × 12 tapered roller bearings and a plastic cage from a 6 ½ × 12 bearing.

The natural frequencies of the cages were determined and then compared to the exciting frequencies of the bearings. Vibrations, internal and external to the bearing were measured at various simulated train speeds. The magnitude and frequencies of these excitation vibrations were input into the finite element modeling software, ALGOR®, to find the response of the cage. It was found that the stresses generated in the small end cage pocket of larger 7 × 12 steel cages were as much as twice that of the 6 ½ × 12 steel cages. The stress generated at the pocket of the 6 ½ × 12 plastic cage was smaller than the 6 ½ × 12 steel cage.
Thermoplastic Stress Analysis of Graphite Reinforced Composite Cantilever Beam of Arbitrary Orientation, Subjected to Uniformly Distributed Loads
Authors: Okumus Fuat , Turgut Aydin , Sancaktar Erol
Published: December 2020

In this study, an elastic-plastic stress analysis is performed in a carbon fiber reinforced thermoplastic composite beam, which is loaded uniformly at the upper surface. An analytical solution is obtained including both the governing differential equations and boundary conditions. The composite beam is loaded uniformly at the upper surface, therefore the normal stress component σy is neglected in comparison with other stress components. The orientation angle of the composite is changed as 0°, 15°, 30° and 45°. The intensity of the residual stress component of σx is maximum at the upper and lower surfaces of the composite beam. The intensity of the residual stress component of the shear stress τxy is maximum around the central axis for the beam.
Sun glints and luminous wriggles by the seashore
Authors: De Luca R.
Published: December 2020

A rather delightful optical phenomenon, related to sun glints observed by the seashore, is illustrated: tiny spots of lights can be seen to move randomly in front of an observer wearing sunglasses with polarized lenses. On the seabed beneath the shallow waters, luminous wriggles can also be detected with or without sunglasses. By means of Fresnel equations, a plausible explanation of these two optical phenomena is given.
Standing waves in a coaxial cable: A simple and low-cost experiment for an instructional wave laboratory
Authors: Lenart Vinícius M. , Szmoski Romeu M. , Turchiello Rozane F. , Gómez Sergio L.
Published: December 2020

The basic physics of traveling waves and standing waves are fundamental topics in the education of science and engineering students. These concepts are found in many areas, including classical mechanics, quantum mechanics, and electromagnetism. Typically, laboratory demonstrations of traveling waves and standing waves are based on mechanical systems such as vibrating strings and sound waves. This paper presents a simple benchtop experiment for producing and observing electromagnetic standing waves in a coaxial cable and determining the phase velocity of their underlying component traveling waves. We also discuss the experimental requirements for this experiment.
High-speed escape from a circular orbit
Authors: Blanco Philip R. , Mungan Carl E.
Published: December 2020

You have a rocket in a high circular orbit around a massive central body (a planet or the Sun) and wish to escape with the fastest possible speed at infinity for a given amount of fuel. In 1929, Hermann Oberth showed that firing two separate impulses (one retrograde and one prograde) can be more effective than a direct transfer that expends all the fuel at once. This is due to the Oberth effect, whereby a small impulse applied at periapsis can produce a large change in the rocket's orbital mechanical energy, without violating energy conservation. In 1959, Theodore Edelbaum showed that this effect could be exploited further by using up to three separate impulses: prograde, retrograde, and then prograde. The use of more than one impulse to escape can produce a final speed even faster than that of a fictional spacecraft that is unaffected by gravity. We compare the three escape strategies in terms of their final speeds attainable, and the time required to reach a given distance from the central body. To do so, in the Appendix we use conservation laws to derive a “radial Kepler equation” for hyperbolic trajectories, which provides a direct relationship between travel time and distance from the central body. The 3-impulse Edelbaum maneuver can be applied to interplanetary transfers, exploration of the outer solar system and beyond, and (in time reverse) efficient arrival and orbital capture. The physics principles employed are appropriate for an undergraduate mechanics course.
Chaos in the monopole ion trap
Authors: Perez Edgar , Essick John
Published: December 2020

The theory and practical design of a monopole ion trapping system are presented, along with our experimental observations of nonlinear motion of a single charged polyethylene microsphere in the trap. For these observations, the trap was operated at a drive frequency of 70 Hz and easily produced voltages in the kV range. The resulting ion motion was captured using a high-speed camera acquiring images at up to 4000 frames per second. These data yielded time series, phase space portraits, and power spectra of the ion motion in a range of applied voltages, allowing us to observe a period-doubling route to chaos and a period-3 window within the chaotic regime. It is shown that these observations agree with a numerical integration of the ion's nonlinear equation of motion in the monopole electric field.
Teaching college writing from a physicist's perspective
Authors: Thompson Kristen L. , Kuchera Anthony N. , Yukich John N.
Published: December 2020

College writing has conventionally been taught by faculty in the humanities, but many schools have begun to encourage writing instruction by faculty from a variety of disciplines. Our institution, Davidson College, has a college-wide writing requirement of all first-year students, and encourages a broad spectrum of faculty to contribute to the writing curriculum. We describe our recent experiences teaching three different writing courses that focus on topics in 20th century physics and astronomy. The goal of this teaching is to prepare students to be intellectual writers on scientific and technical topics, while focusing on concepts in physics and related areas. The writing and rhetorical skills emphasized in our classes have wide applicability for students seeking various professions. Our writing courses have required us to develop teaching methods unfamiliar to some physicists but have proven to be popular with many students and warmly received by our colleagues. Teaching these courses has helped to increase student interest in physics and has also helped the authors to grow intellectually and professionally. Here, we share our experiences teaching courses within our college's first-year writing program. We find the endeavor to be beneficial to our college, faculty, and students and hope to encourage other non-writing faculty to consider contributing to the writing programs at their institutions.
The Feasibility of a Combined Lifestyle Physical Activity and Cognitive Training Intervention to Prevent Cognitive Impairment in Older Women With Cardiovascular Disease
Authors: Halloway Shannon , Wilbur JoEllen , Braun Lynne T. , Schoeny Michael E. , Volgman Annabelle Santos
Published: December 2020

Background: Cognitive impairment disproportionately affects older women with cardiovascular disease (CVD). Physical activity (PA) and cognitive training (CT) may have synergistic effects in combined interventions. However, no combined intervention has targeted women with CVD or utilized a sustainable and preferable lifestyle approach. The purpose was to test feasibility and acceptability of the 24-week MindMoves program, a lifestyle intervention that combined PA and CT developed for older women with CVD. Methods: The PA component included goal setting with Fitbits and 5 behavioral group meetings. The CT component was evidence-based BrainHQ delivered on a tablet in three 30-minute weekly sessions. Participants included 10 women aged ≥65 years with CVD. Exclusion criteria were cognitive impairment, regular PA, and CT use. Measures were feasibility (recruitment, attendance, participation, retention, and acceptability), change in PA (Fitbit min/steps), and change in cognitive function (NIH Toolbox®). Results: Of the 10 participants, 70% attended ≥4/5 group meetings, and overall attendance was 76%. Participants completed 2.3/3 CT sessions weekly. Participant retention was 100%. Over 90% of participants rated MindMoves with the highest levels of satisfaction. Participants had significant improvements in steps, light PA, and moderate PA, and there was a trend for improved cognition. Conclusions: Findings support testing MindMoves in an efficacy trial.
Multiple Single-Nucleotide Polymorphism Detection for Antimalarial Pyrimethamine Resistance via Allele-Specific PCR Coupled with Gold Nanoparticle-Based Lateral Flow Biosensor
Authors: Jiang Tingting , Huang Yan , Cheng Weijia , Sun Yifei , Wei Wei , Wu Kai , Shen Chen , Fu Xiaolong , Dong Haifeng , Li Jian
Published: December 2020

Molecular genotyping holds tremendous potential to detect antimalarial drug resistance (ADR) related to single nucleotide polymorphisms (SNPs). However, it relies on the use of complicated procedures and expensive instruments.
Salmonella enterica Serovars Dublin and Enteritidis Comparative Proteomics Reveals Differential Expression of Proteins Involved in Stress Resistance, Virulence, and Anaerobic Metabolism
Authors: Martinez-Sanguiné A. Y. , D’Alessandro B. , Langleib M. , Traglia G. M. , Mónaco A. , Durán R. , Chabalgoity J. A. , Betancor L. , Yim L.
Published: December 2020

The Enteritidis and Dublin serovars of
Salmonella enterica
are phylogenetically closely related yet differ significantly in host range and virulence.
S
. Enteritidis is a broad-host-range serovar that commonly causes self-limited gastroenteritis in humans, whereas
S
. Dublin is a cattle-adapted serovar that can infect humans, often resulting in invasive extraintestinal disease.
Lipopolysaccharide Transport Involves Long-Range Coupling between Cytoplasmic and Periplasmic Domains of the LptB
2
FGC Extractor
Authors: Lundstedt Emily A. , Simpson Brent W. , Ruiz Natividad
Published: December 2020

Gram-negative bacteria are intrinsically resistant to many antibiotics due to the presence of lipopolysaccharide (LPS) at their cell surface. LPS is transported from its site of synthesis at the inner membrane to the outer membrane by the Lpt machine.
Driving Laboratory Standardization of Bacterial Culture and Antimicrobial Susceptibility Testing in Veterinary Clinical Microbiology in Europe and Beyond
Authors: Timofte Dorina , Broens Els M. , Guardabassi Luca , Pomba Constanca , Allerton Fergus , Ikonomopoulos John , Overesch Gudrun , Damborg Peter
Published: December 2020

Globally, antimicrobial resistance is one of the most important public health challenges in which the clinical microbiology laboratory plays a critical role by providing guidance for antimicrobial treatment. Despite the recognition of its importance, there is still a real need for the standardized training of clinical microbiologists and harmonization of diagnostic procedures.