bluuebunny/crossref_metadata_2025 huggingface dataset:
Chip Formation When Hard Turning Steel
Authors: Vyas Amitabh , Shaw Milton C.
Published: March 2022

Hard turning of machine parts is a production process that holds considerable promise for the future since it is an effective means of increasing productivity. Instead of machining a product in the soft state, hardening the part by heat treatment, and then providing the required finish and dimensional accuracy by grinding the expensive grinding operation is eliminated. This is possible because of the availability of improved hard tool materials (polycrystalline cubic boron nitride and ceramics), and more rigid machine tools. The nature of chip formation in hard turning is quite different than in more conventional machining. As might be expected, fracture plays a much more important role in the machining of very hard materials. As in all facets of production engineering it is important to identify the key element involved in the operation and to give far less attention to secondary effects that tend to cloud an issue. The objective of this paper is to establish the key action involved in hard turning chip formation and then to develop the mechanics involved as far as possible at the moment.
White Layers and Thermal Modeling of Hard Turned Surfaces
Authors: Chou Y. Kevin , Evans Chris J.
Published: March 2022

White layers in hard turned surfaces are identified, characterized and measured as a function of tool flank wear and cutting speed. White layer depth generally increases with flank wear. It also increases with speed, but approaches an asymptote. A thermal model based on Jaeger’s moving heat source problems (Jaeger, 1942) is applied to simulate the temperature field in machined surfaces and to estimate white layer depth in terms of the penetration depth for a given critical temperature. The analysis shows good agreement with the trend in experimental results. White layer formation seems to be dominantly a thermal process, possibly plastic strain activated; flank wear land rubbing may be a primary heat source for white layer formation. A strong material dependence of surface alteration is also observed.
Some Observations on the Uniqueness of Machining
Authors: Madhavan V. , Chandrasekar S.
Published: March 2022

It has been suggested by R.Hill (1954b) that the machining process is not uniquely determined by the input conditions. A finite element simulation capable of representing the physics behind machining with high fidelity is used to explore the uniqueness of the machining process. It is found that a stable unique mode of deformation does exist for a given set of input conditions. Experimental and theoretical studies also indicate that the mode of deformation is indeed unique and that this uniqueness is possibly due to the applicability of the principle of minimization of plastic work to the machining process.
A Study of Wave-Removing Cutting Process Using a Model of Shear Zone With Parallel Boundaries
Authors: Hayajneh M. T. , Osman M. O. M. , Latinovic V. N.
Published: March 2022

A shear zone model with parallel boundaries is used to formulate a cutting force model and analyze the dynamic behavior of the machining process in orthogonal cutting. The cutting system was modeled using a single degree-of freedom dynamic system where the variations of the cutting forces are represented by their total differentials. The model is derived based on the principles of the cutting mechanics, and takes into account the variations of the shear stress in the primary deformation zone as well as at the chip-tool interface (secondary deformation zone).
Closing the Gap Between CAD/CAM and Machining Process Simulation: A Generic Solution
Authors: El-Mounayri Hazim A. , Imani Behnam M. , Elbestawi Mohamed. A. , Spence Allan D.
Published: March 2022

In this paper, an enhanced CAD/CAM system for simulating 3-axis milling of complex parts is proposed. The system consists of the conventional CAD/CAM system enhanced with a milling process simulator. The latter includes a geometric module and a physical module. The geometric simulator integrates solid, surface and curve modelling to accurately represent the geometric entities involved in the milling simulation and extract the geometric information required for predicting different process parameters. The physical simulator is composed of force models for flat and ball end mills which compute instantaneous cutting forces. The applicability of the approach is demonstrated for the case of 3-axis milling using a ball end tool. The validity is shown by predicting cutting forces and comparing them with experimental measurements. This system can be used to verify and optimize NC codes, thus contributing to improving the reliability, accuracy, and productivity of NC machining.
A Dynamic Model of the Cutting Force System in Peripheral Milling Characterizing the Effects of Flank Face Interference
Authors: Narayanan Kannan , Ranganath Santosh , Sutherland John W.
Published: March 2022

An enhanced model for the dynamic behavior of the end milling process is described. The model predicts the cutting forces and cutter deflections by including the effects of the flank face interference mechanism in addition to the chip removal effects. The interference mechanism is accounted for by considering the flank interference forces to be proportional to the interference volume. The volume of interference is estimated numerically. The total force acting on the tool is a combination of the forces due to the cutting action and forces due to the interference. Experiments performed on 6061-T6 Aluminum validate the simulation results.
A 3-D Kinematic Model of Complex Chip Curling With Chip Breaker Tools in Metal Cutting: Part I — Analytical Modelling
Authors: Fang Y. J. , Fang X. D. , Basu A.
Published: March 2022

It has been realised that the analytical model of 3-D chip curling plays a central role in the chip formation that would predict the chip forms/shapes efficiently for the aim of chip control. The purpose of the two-part paper is to investigate and model the 3-D chip curling processes in theory. In part I, an analytical modelling procedure is described in detail and a general mathematical model for predicting chip forms /shapes in 3-D cutting processes with complex chip breaker tools is presented on the basis of three basic chip curling patterns, i.e. up-curl, side-curl and twisting. In part II, the theoretical analysis and discussion have been done systematically based on the model presented. Therefore a group of criterions for the effects of three chip angular velocity components ωx, ωy, ωz, and chip flow angle η0 on the chip forms/shapes is derived. The varying tendency of the chip radius and chip pitch with varying ωx, ωy, ωz, and η0 is discussed based on the group of criterions. For better understanding, a group of 3-D diagrams is given to visualise the varying tendency of chip geometry. The 3-D analytical model and the group of criterions presented in part I and part II of the paper reveal new insights in to the nature of chip curling in 3-D machining in theory and are significant for the analytical prediction of the chip curling and the chip breaking, as well as the geometric design of the chip breaker/groove.
An Experimental Investigation of the Variability of Edge Hones and Their Effects on Machining Forces
Authors: Schimmel Roy J. , Manjunathaiah Jairam , Endres William J.
Published: March 2022

A new, non-contact instrument is identified for measuring the edge radii of cutting tools to a very high degree of accuracy. The instrument uses white light interferometry combined with accurate axis movements and software algorithms to make the measurements. Using this technique, the edges of several commercial cutting inserts are measured and compared. It is found that the radius of the hone varies along the length of the edge in a parabolic manner. The difference between the edge radius at the center of the edge to the radius at the start of the nose can be as large as 25μm (0.001in). The variation between the edges on an insert and across inserts in a batch of tools can be as high as 25μm (0.001in). In order to investigate the effect of these variations in edge radii on cutting forces, orthogonal cutting tests are performed with tools of measured edge radius in the zone of cut. The results indicate that the machining forces (especially the thrust force component) are sensitive to changes in edge radius on the order of measured variations.
Design of a High Speed Milling Machine for Aluminum Aircraft Parts
Authors: Tlusty Jiri , Smith Scott , Badrawy Sinan J. , Smith David A. , Smith Andrew P.
Published: March 2022

This paper deals with the design of a medium-sized high speed milling machine for end milling of thin-walled aluminum parts. Specifications for top parameters of spindle speed, feedrates, and accelerations are derived, and it is shown how the worldwide maximum values have been achieved. Design criteria of stiffness of the individual subsystems and high gain of control loops are discussed, and solutions are presented. Strategies for milling of thin ribs and thin webs arc explained, and examples of cutting conditions for two sample parts are given as machined on the three-axis configuration of the machine Alternative designs for extending the machine to five axes are described.
Analysis of Tapered Roller Bearing Stiffness
Authors: Rowell Timothy , Shin Yung C.
Published: March 2022

This paper presents a computational model and analysis of tapered roller bearing stiffness. A five degree of freedom model is coupled with a spindle model and implemented in a computer code. The predicted results are verified by other published data. The importance of proper modeling of the spindle and bearing interaction is identified. A sensitivity analysis of the bearing stiffness in terms of geometric and operational parameters is presented.
Nonlinearities in a Single Nut, Preloaded, Precision Ball Screw
Authors: Cuttino James F. , Dow Thomas A. , Knight Byron F.
Published: March 2022

The nonlinear performance of a single-nut, preloaded ball screw actuator is analyzed in this paper. The study identifies the source of nonlinear torque in the ball screw and subsequently maps that torque into the nonlinear displacement response due to windup in the shaft. The study is complemented with an experimental verification using a small angle rotation fixture (ARC) to input very small amplitude angular displacements to the screw while measuring induced torque and displacements. The experimental results are obtained from a Precision Linear Optimization Testbed (PLOT) which was developed to study the ability of different actuator systems to provide long range motion with nanometer accuracy. The analysis is conducted for the case of no axial loading. The study shows that the nonlinearities in the ball screw originate in the rolling friction between the balls and the races which induces torque in the nut and subsequently windup in the shaft. It also shows that the torque can be deduced from a relationship of the torque between a ball spinning in a race.
Simulation and Measurement of Chatter in Diamond Turning
Authors: Yantek David S. , Marsh Eric R. , Davies Matthew A. , Gilsinn David E.
Published: March 2022

This paper considers chatter in diamond turning of aluminum. A nonlinear chip area model is developed for use with the classic single degree of freedom cutting model. The chip area model is formulated as a function of the change in depth of cut between consecutive passes. This function is shown to be highly dependent on the quadratic term when turning the diameter of cylindrical workpieces with round-nosed diamond tools. The cutting model is further extended to include an impact disturbance to the cutting process. The recent research in ultra-precision machining is incorporated to properly account for the rise in specific cutting energy at extremely light depths of cut. Simulations of the resulting tool displacement show close agreement with experimental measurements.
Autonomous Calibration of Hexapod Machine Tools
Authors: Zhuang Hanqi , Liu Lixin , Masory Oren
Published: March 2022

Hexapod machines are emerging as a new type of CNC machine tools. Among other things, stringent calibration is an important means to improve their accuracy. Traditionally, to perform system calibration, one needs to measure a number of machine poses using an external measuring device. However, this process is often labor-intensive and invasive, and difficult for on-line calibration.

In this paper, a systematic way of self-calibrating a hexapod machine tool is introduced. By adding a small number of redundant internal sensors, errors of the hexapod machine tool can be measured. This approach has the potential of automatically producing accurate measurement data over the entire workspace of the system with an extremely fast measurement rate. Once the measurement data is available, a recursive filter is applied to estimate machine parameter errors from the predicted geometric errors, and to update the model residing in the machine controller. Thus, it is possible to dynamically calibrate and compensate for various types of machine errors including those induced by thermal and loading variations, without interrupting the normal operation of the machine tool. To verify the concept, preliminary experimental studies were conducted on a Stewart platform built at Florida Atlantic University.
Compatibility Analysis of Vehicle-to-Vehicle in Head-On Collision
Authors: Jawad Saad A. W.
Published: March 2022

An eight-degrees of freedom, two dimensional lumped-mass simulation model have been developed to study aggressivity of mass and stiffness ratio of vehicles in head-on collisions. Other factors like length of crumple zone, offset overlap and speed are also considered. The model assumes that the two colliding structures geometrically interact with each other. Engine assembly mass, primary and secondary stiffness parameters are considered in the model. Three injury risk criteria have been considered in this study; delta V or change in velocity of vehicle after impact, maximum acceleration sustained by the passenger compartment throughout impact, and length of deformation sustained by the car front. The most crucial aggressivity parameter is the mass ratio for the delta V criterion. The second and third aggressivity parameters are mass ratio and stiffness ratio for deformation length criterion. A slightly softer and longer crumple zone is proposed to be used for heavier vehicles to achieve compatibility of crashes of vehicles of different mass. This measure would alleviate aggressivity by a factor of about 20%. It was found that both mass and stiffness ratio have no aggressivity on the partner vehicle, as far as acceleration injury criterion is concerned. Acceleration is determined by the vehicle’s own mass and stiffness.
Aluminum Intensive Vehicle Crashworthiness Design Approach
Authors: Barbat Saeed D. , Mahmood Hikmat F. , Prasad Priya P.
Published: March 2022

A successful design approach and procedures for Ford’s Aluminum Intensive Vehicle (AIV) build and evaluation with emphasis on crashworthiness and front end design are described. Several issues and concerns related to design and assembly of all-aluminum body structure such as material selection, joining techniques, crush behavior and structural integrity were addressed and resolved. An experimental and analytical approach was adopted to investigate the static and dynamic behavior of spot-welded and weld-bonded aluminum crush members. Design and analyses tools for establishing target component forces, assessing energy absorption and stability of collapse of the front end structure are also presented. Sections, components and sub-system analyses were conducted to establish the AIV target forces, energy levels and collapse modes. Extensive testing on generic section columns and production component and sub-systems were also performed. This helped in addressing critical issues associated with the introduction of all aluminum body structure into high volume production. Other tests were also conducted for design verification.

Aluminum alloys AA5XXX and AA6XXX-T4 were used for the structural components of the AIV. AA5XXX was used for the front end frame and a mix of AA5XXX/AA6XXX was used for the roof structure. Doors and hoods utilized AA6XXX-T4 alloy for their construction. It was demonstrated that the all-aluminum body structure can achieve equivalent crashworthiness performance as its steel counterpart with a weight saving of 30%. The all-aluminum vehicles were tested in frontal and rear crash, roof crush, side intrusions in side impact and all met or exceeded the Federal Motor Vehicle Safety Standard (FMVSS) requirements.
Application of Optical Triangulation Ranging in Automobile Collision Avoidance
Authors: Saikia Siddarth
Published: March 2022

This system is conceptualised for the avoidance of extensive damage during collision in road vehicles. The system uses optical triangulation to gauge distances in the environment.

A laser beam will scan the environment horizontally, a camera will locate the image of the reflected ray. The data of the scan will be analysed as per the formulated algorithm, if certain parameters are exceeded and a collision is deduced to be inevitable, then external airbags mounted in the front and on the sides of the car will be inflated.

Better accuracy of optical triangulation ranging over radar ranging in short distances, enables the use of external air bags along with other regular collision avoidance features.
Investigation of Brain Injury Kinematics: Introduction of a New Technique
Authors: Hardy Warren N. , Foster Craig D. , King Albert I. , Tashman Scott
Published: March 2022

The principal focus of this study is the measurement of relative brain motion with respect to the skull and between different regions of the brain. Using a high-speed bi-planer x-ray system and reduced density targets (RDT’s), the strain in a relatively small volume of brain can be determined. Relative motion between the brain and skull can be determined using implanted triaxial neutral density accelerometers (NDA-3’s) and a rigid-body accelerometer array (3-2-2-2) mounted to the apex of the skull. A suspension fixture is used for inverted, isolated-head testing. Two occipital impacts, 2.7 m/s and 4.2 m/s, are conducted on a single specimen. The high-speed x-ray system provides validation of the NDA-3 performance, and allows tracking of the RDT locations. Relative displacements between the brain and skull are found to be on the order of 3–5 mm, and stretch levels within the RDT array reach approximately 9 percent. These initial results provide the opportunity to introduce the new technologies and techniques designed for use in this ongoing study.
Numerical Characterization of the Viscoelastic Behavior of the Butyl Rubber in the Hybrid III Dummy Neck
Authors: Deng Yih-Charng , Li Xiaowei
Published: March 2022

Quasi-static and stress relaxation tests were conducted to characterize the rubber material in the Hybrid III dummy neck structure. Test data showed that the rubber can sustain large deformation without failure and the material exhibited nonlinear elastic behavior and high viscous properties. Analytical relaxation responses were obtained for material model Type 6 and Type 77 in the DYNA3D program for linear loading conditions. Based on these analytical responses a numerical procedure was developed for identifying the viscoelastic parameters for the two material types. Due to its generality we found that material Type 77 is better suited to simulate the viscoelastic behavior of the rubber. Using this material model, the relaxation response of the rubber can be captured with a high degree of accuracy.
Accident Investigation for Safety Regulations, Crashworthiness, Occupant Protection, Biomechanics: A Survey of the CIC Approach
Authors: Kecman Dusan
Published: March 2022

The paper presents a summary of the recent activities in the Cranfield Impact Centre (CIC) in the fields of : accident investigation leading to development of the new international safety regulations in buses, heavy goods vehicles (also with reference to Formula I cars); air accident investigation and flight data visualiser software ; crashworthiness of aircraft, cars, buses, rail vehicles, safety seats and crash data recording ; pedestrian and occupant / pilot protection in vehicle cab interiors and military aircraft cockpits and biomechanics studies of the brain injuries and femur tolerance levels to bending. The general approach combines the systems approach to problems, hybrid method of treating components both separately and as part of the whole system and uses design, analysis and test work under one roof.
Characterisation of Open-Cell Aluminum Alloy Foams as Heat Sinks for High Power Electronic Devices
Authors: Bastawros A.-F. , Evans A. G.
Published: March 2022

A heat sink comprising an Al alloy open cell material within an insulated channel is described. It is attached to a silicon substrate and cooled with circulating air. The influence of foam morphology and heat sink dimensions on both the heat transfer coefficient and the pressure drop are measured. Trends in the cell wall diameter, d, the heat sink thickness, b, and the air velocity, v, are established. The findings are compared with a model based on the cross flow of a fluid over a bank of cylinders. There is qualitative consistency with the measured effects of d and v, but significant differences in details. Moreover, measured trends with b oppose those in the model. The implication is that the fluid flows are influenced by the heat sink thickness. Further studies are needed to assess these effects.
Thermo-Mechanical Analysis of Solder-Sealed Electronic Modules During Power Cycling
Authors: Sherif Raed A. , Edwards David L. , Ellsworth Michael J.
Published: March 2022

This paper is concerned with the design of hermetic, solder-sealed electronic modules. In particular, the thermal strains developing in the solder seal, potentially leading to solder cracking and module loss of hermeticity are analyzed using a 3D FEM model. It is shown that a full transient thermo-mechanical analysis of the module during power cycling is needed to be able to select the right lid material in order to maximize the solder fatigue life. This is especially true when the module power dissipation is too high for thermal cycling to be representative of module operating conditions.

The IBM AS/400 MCM, called Muskie, is considered as a model problem. This high performance MCM dissipates about 4–5 times the power of its predecessors. At this high power, it is shown via modeling that traditional alumina lids which match the ceramic substrate CTE will lose hermeticity prematurely in the field. Model verification was done by power cycling a set of nine modules and reading out their hermeticity level every few hundred cycles. The experimental results agreed well with the model. The model was then used to select another lid material with an optimized lid-substrate CTE mismatch. The new lid material, made of WCu, has been used successfully by IBM over the past two years.
Experimental Study of Automotive Brake System Temperatures
Authors: Emery A. F. , Kumar P. , Firey J. C.
Published: March 2022

Modern automotive disk brake systems can generate extremely high temperatures under high but short time braking loads or relatively light but continuous braking. One consequence of the high disk and pad temperatures is a gradual heating of the brake hydraulic fluid which can lead to boiling of absorbed water and loss of braking. This paper describes an experiment in which fluid and braking system temperatures, pressures, and operating conditions (vehicle speed, braking energy dissipation, etc) were measured in three different classes of operating vehicles during brake application and subsequent brake release. Brake failure was observed and correlated to moisture content of the fluid, severity of brake application and application time. Temperatures predicted by a finite element analysis agree well with the measured temperatures and can be used to estimate the time at which the fluid boils.
Hydrostatic Response of Piezoresistive Stress Sensors
Authors: Kang Y. , Mian A. K. M. , Suhling J. C. , Jaeger R. C.
Published: March 2022

The (111) surface of silicon offers unique advantages for fabrication of piezoresistive stress sensors. Resistive sensor elements fabricated on this particular surface respond to all six components comprising the state of stress. Hence, a multi-element rosette has the capability of measuring the complete stress state at a point in the material. To extract the stress state at points on the die from the resistance changes measured with the sensor rosettes, it is necessary to have accurately calibrated values of six piezoresistive coefficients. Four-point bending and wafer-level calibration methods can measure four out of six piezoresistive coefficients for both p- and n-type resistors. To measure the other two coefficients, a hydrostatic test method has been developed where a high capacity pressure vessel is used to apply triaxial load on a single die. During the test procedure, resistance changes of resistors on the die are monitored. The slopes of the adjusted resistance change versus pressure plots are then used to calculate the desired last two coefficients. A step-by-step hydrostatic test procedure is demonstrated and sample data are presented.
Creep Behavior Study of Plastic Power Package by Real Time Moiré Interferometry and FEM Modeling
Authors: Zou Daqing , Wang Jianjun , Lu Minfu , Liu Sheng
Published: March 2022

In this paper, the creep behavior of the plastic power package at high temperature 155 °C was studied by real time moiré interferometry and FEM modeling. 1200 l/mm grating was replicated onto the cross-section of the specimen at room temperature. The specimen was held at 155°C (around the Tg of the epoxy molding compound) in the vacuum chamber for about 13 hours. The thermal deformation and creep of the specimen was recorded and measured in situ by moiré interferometry. The experimental results show that creep deformation occurs in the epoxy molding compound. The non-linear viscoelastic constitutive model was used for FEM simulation. The simulation results were compared with the experimental results and they were matched quite well on the global deformation of the specimen. The calculation results also show that, accompanied with the global creep deformation in molding compound epoxy, local stress concentration decreased significantly.
Resolving Deformation Field Near Corners and Interfaces by Phase Shifting Moiré Interferometry
Authors: Zou Daqing , He Xiaoyuan , Liu Sheng , Guo Yifan , Dai Fulong
Published: March 2022

Although it is challenging to resolve deformation fields near corners or interfaces for layered structures, it is essential for a measurement technique to deal with of stress/strain concentrations, strain gradients, failure initiation and growth, local microstructure evolutions, etc. In this study, an innovative phase shifting technique is proposed, coupled with an image processing software, to investigate several interesting problems in electronic packaging. A power plastic IC package and a flip-chip package are selected to demonstrate the powerfulness of the system. A nanoscale deformation field is obtained for both the corner area and the underfilled containing flip-chip solder balls.
Testing and Constitutive Modeling of Thin Polymer Films and Underfills by a 6-Axis Submicron Tester
Authors: Qian Zhengfang , Lu Minfu , Wang Jianjun , Liu Sheng
Published: March 2022

The thermo-mechanical testing of Polycarbonate, Kapton, and Nylon films and underfill HYSOL FP4526 is reported, including the details of specimens, test procedures, and the 6-axis mini tester. The constitutive framework proposed for polymer films is, for the first time, applied to model the thermo-mechanical properties of underfill HYSOL FP4526 in this paper.
Thermal Mechanical Properties of Two Solder Alloys
Authors: Ren Wei , Qian Zhengfang , Lu Minfu , Liu Sheng , Shangguan Dongkai
Published: March 2022

The thermal-mechanical behaviors of a new lead free solder and eutectic 63Sn37Pb are investigated in this paper. A series of tests including tensile, creep and fatigue, are carried out on a computer controlled 6-axis mini fatigue tester. The thin strip specimen is used in this research, which is specially designed and verified to be suitable for the testing of solder alloys and comparable to the data from the literature. Based on the experimental study it is clear that the new lead free solder alloy is a potential replacement for the currently used Sn-Pb solders for electronics packaging applications.
Laminar Natural Convection in a Triangular Enclosure
Authors: Hasani S. M. F. , Chung B. T. F.
Published: March 2022

Previous studies on buoyancy driven pure convective motion in triangular enclosures have produced conflicting results in regards to the convective stability of the fluid. The purpose of this paper is to address many of the unexplained observations of previous studies as well as to provide validation of some of the earlier results. The time-dependent, two-dimensional vorticity transport and energy equations are solved numerically for a triangular enclosure having isothermal boundary conditions at the base and inclined surfaces by using the third-order accurate QUICK scheme. All previous studies had utilized schemes of second-order accuracy. The vorticity at the boundaries is computed by using second-order accurate, third degree polynomial approximation of Jensen’s type and the stream function equation is solved by successive overrelaxation. Results are presented for air as the convective fluid with Rayleigh numbers in the range of 7.1 × 102 to 7.1 × 105 while the aspect ratio of the enclosure varies from 0.2 to 1.0. Two types of flow configurations are investigated with the inclined surfaces considered hot for one and cold for the other. The paper discusses in detail the phenomena of cell bifurcation, cell detachment and reversal in cell rotation observed for fluids heated from the base. Numerical correlations are obtained for steady state values of Nusselt number as a function of Rayleigh number and aspect ratio.
On the Recirculation Zones in a Cylindrical Container
Authors: Jahnke C. C. , Valentine D. T.
Published: March 2022

The flow field induced inside a cylindrical container by the rotation of the two end walls is described. It is shown that stagnation points leading to separation bubbles occur on the axis of rotation and/or the bottom end wall for certain ranges of the characteristic parameters; the Reynolds number, the aspect ratio of the container, and the ratio of the rotation rates of the end walls. Flow fields in a container of aspect ratio 2.0 is examined for Reynolds numbers from 100 to 3000 and ratios of the rotation rates of the top and bottom end walls from −0.10 to 1.0. For a range of ratios of the rotation rates of the top and bottom end walls and Reynolds numbers it is shown that ring vortices surrounding a columnar vortex core exist.
Interaction Between a Liquid and a Moving Blade
Authors: Yedidiah S.
Published: March 2022

This paper discusses different approaches toward calculating the effect of a blade moving in a liquid. It demonstrates that a recently-developed approach has the potential to produce more reliable results, than either Euler’s equation or the aerofoil theory.

This conclusion is supported by results of actual tests.
Finite Element Modeling of Submerged Aquaculture Net-Pen Systems
Authors: Gosz M. , Kestler K. , Swift M. R. , Celikkol B.
Published: March 2022

In the design of offshore aquaculture net-pens, computer based models are needed in order to evaluate and optimize design criteria prior to the construction and testing of expensive prototype net-pen systems. Two fundamental criteria that must be addressed are dynamic response and reliability. Practical computer modeling methods must be capable of handling the complex fluid/pen interactions that occur in high energy open ocean environments for a broad range of net-pen designs. The resulting dynamic response and stress and stress cycling information are essential input for design modification and lifetime predictions. In the paper, the finite element method is used to predict the three-dimensional dynamic response of submerged offshore net-pens and their associated moorings. Solid-framed and pre-stressed net-pen designs are modeled using simple structural elements. The solution to the nonlinear dynamic equilibrium equations is obtained using an incremental-iterative method based on an updated Lagrangian formulation. The resulting semi-discrete equations are integrated in time using the trapezoidal rule, and full Newton-Raphson equilibrium iteration is employed during each time step. Fluid loading is implemented using the Morison equation, along with Airy wave theory. The contributions to the element stiffness matrices that arise from the fluid loading are continually updated during the iterative process. Initial validation of the finite element results for a basic cage configuration is made by comparison to experimental data obtained from a simple cage model subjected to a constant current in a flume.
“Mirror, Mirror, Am I as My Coach Sees Me?”: Discrepancy Between Athlete Self-Appraisals and Reflected Appraisals of Their Coach, and Relations With Athlete Burnout
Authors: Trouilloud David , Isoard-Gautheur Sandrine , Roux Valentin
Published: March 2022

Using a person-centered approach, this study was conducted to identify (a) specific athlete profiles in terms of degree of discrepancy between their self-appraisals and the reflected appraisals of their coach and (b) the relations between these profiles and athlete burnout. Athletes (N = 369; Mage = 21.15 years) fulfilled measures of self-appraisals, reflected appraisals of their coach, and burnout. Latent profile analysis allowed the identification of three profiles: concordance (84%), positive discrepancy (11%), and negative discrepancy (5%). Analyses revealed relationships between athletes’ profile membership and the three dimensions of burnout: emotional and physical exhaustion, sport devaluation, and reduced sense of accomplishment. More specifically, results indicated that athletes with a positive discrepancy profile (i.e., who rated themselves more positively than they think their coaches see them) were more at risk of burnout. This study contributes to existing research on psychosocial determinants of athlete burnout in the context of the coach–athlete relationship.
Topological magnon band structure of emergent Landau levels in a skyrmion lattice
Authors: Weber T. , Fobes D. M. , Waizner J. , Steffens P. , Tucker G. S. , Böhm M. , Beddrich L. , Franz C. , Gabold H. , Bewley R. , Voneshen D. , Skoulatos M. , Georgii R. , Ehlers G. , Bauer A. , Pfleiderer C. , Böni P. , Janoschek M. , Garst M.
Published: March 2022

The motion of a spin excitation across topologically nontrivial magnetic order exhibits a deflection that is analogous to the effect of the Lorentz force on an electrically charged particle in an orbital magnetic field. We used polarized inelastic neutron scattering to investigate the propagation of magnons (i.e., bosonic collective spin excitations) in a lattice of skyrmion tubes in manganese silicide. For wave vectors perpendicular to the skyrmion tubes, the magnon spectra are consistent with the formation of finely spaced emergent Landau levels that are characteristic of the fictitious magnetic field used to account for the nontrivial topological winding of the skyrmion lattice. This provides evidence of a topological magnon band structure in reciprocal space, which is borne out of the nontrivial real-space topology of a magnetic order.
Vernier template synthesis of molecular knots
Authors: Ashbridge Zoe , Kreidt Elisabeth , Pirvu Lucian , Schaufelberger Fredrik , Stenlid Joakim Halldin , Abild-Pedersen Frank , Leigh David A.
Published: March 2022

Molecular knots are often prepared using metal helicates to cross the strands. We found that coordinatively mismatching oligodentate ligands and metal ions provides a more effective way to synthesize larger knots using Vernier templating. Strands composed of different numbers of tridentate 2,6-pyridinedicarboxamide groups fold around nine-coordinate lanthanide (III) ions to generate strand-entangled complexes with the lowest common multiple of coordination sites for the ligand strands and metal ions. Ring-closing olefin metathesis then completes the knots. A 3:2 (ditopic strand:metal) Vernier assembly produces +3
1
#+3
1
and −3
1
#−3
1
granny knots. Vernier complexes of 3:4 (tetratopic strand:metal) stoichiometry selectively form a 378-atom-long trefoil-of-trefoils triskelion knot with 12 alternating strand crossings or, by using opposing stereochemistry at the terminus of the strand, an inverted-core triskelion knot with six alternating and six nonalternating strand crossings.
Life-changing biology
The Genesis Machine
Amy Webb and Andrew Hessel
PublicAffairs, 2022. 368 pp.
Authors: Woolfson Adrian
Published: March 2022

Genetically engineered genomes will disrupt the bioeconomy and rewrite human nature—are we ready?
Anthropogenic influences on bee foraging
Authors: Goulson Dave , Nicholls Elizabeth
Published: March 2022

Efficient foraging is vital to bee fitness but is challenging in the Anthropocene
Black colleges can’t do it all
Authors: Mervis Jeffrey
Published: March 2022

At historically Black colleges and universities, tight funding threatens an extraordinary record of nurturing Black physicists
Michigan’s surprising path to diversity
Authors: Mervis Jeffrey
Published: March 2022

Black graduate students find a nurturing culture in its applied physics program
In Science Journals
Authors: Norton Melissa , Zahn Laura M. , Stajic Jelena , Yeston Jake , Jiang Di , Smith Keith T. , Vinson Valda , Okamoto Ryo , Purnell Beverly A. , Scanlon Seth Thomas , Hines Pamela J. , Stern Peter , Suleymanov Yury , Osborne Ian S. , Wong Wei , Olingy Claire , Alderton Gemma , Sugden Andrew M.
Published: March 2022

Highlights from the
Science
family of journals
A reconstruction of Apennine uplift history and the development of transverse drainages from longitudinal profile inversion
Authors: Pazzaglia* Frank J. , Fisher† James A.
Published: March 2022

Numerous examples of transverse drainages in the Apennines inspired early, forward-thinking models to describe how rivers established and maintained their courses as mountains were being raised beneath them. We assemble the rate of base-level fall (τ-U) and associated channel χ-z data of ten transverse rivers draining the Apennine pro-wedge using a channel stream power linear inverse approach. We apply the results to evaluate competing models of transverse drainage development as well as the underlying dynamic and tectonic processes responsible for Apennine topography. The channel inversion approach employs the simplifying assumption of uniform uplift and erosion at the catchment scale, but accounts for variable rock erodibility as the first-order determinant of regional, mean channel steepness. Accordingly, local deviations in channel steepness are interpreted by the model as transient upstream-propagating waves of base-level fall originating at the catchment mouth. Modeled timing, rate, and unsteadiness of these base-level falls are broadly consistent with geomorphic, geologic, thermochronologic, and paleo-elevation isotopic data, indicating that the Apennines emerged impulsively at ~2.5 Ma at rates ranging from ~0.2–0.3 mm/yr for the central Apennines to rates of ~0.7 mm/yr for the southern Apennines. Syn-deformation and foreland-propagating superposition dominate transverse drainage development for the northern and north-central Apennines, which are underlain by an intact Adriatic slab. In contrast, further south where a slab window separates the Adriatic slab from the base of the Apennine wedge, dynamic uplift prevails and the transverse drainages have developed in response to regional superposition and integration of catchments through spillover and headwater capture processes.
Periscapular mass in a refugee patient: a case of musculoskeletal extrapulmonary tuberculosis
Authors: Schiller Morgan , Mathews Anita , Buck Sean , Kvach Elizabeth J
Published: March 2022

This report discusses the case of a male refugee from East Africa who presented with persistent right shoulder pain and was found to have a periscapular mass, whose diagnostic and therapeutic delay was due not only to fragmentation of care, but also a lack of awareness of musculoskeletal manifestations of extrapulmonary tuberculosis. This case underscores the importance of including tuberculosis in the differential diagnosis for a variety of symptoms in patients with risk factors, even if they report previous negative screening.
Application of mydriasis and eye steering in ultrawide field imaging for detecting peripheral retinal lesions in myopic patients
Authors: Li Meiyan , Yang Danjuan , Shen Yang , Shang Jianmin , Niu Lingling , Yu Yongfu , Wang Xiaoying , Yao Peijun , Zhou Xingtao
Published: March 2022

Purpose

To compare mydriatic and eye-steering ultrawide field imaging (UWFI) with standard non-mydriatic UWFI examination in detecting peripheral retinal lesions in myopic patients.

Methods

Cross-sectional, observational study. 220 eyes of 110 myopic patients with known peripheral retinal lesions in at least one eye under Goldmann three mirror contact lens examination were recruited. Non-mydriatic standard and eye-steering UWFI images were taken centrally and with eye-steering technique in upper, lower, nasal and temporal gazes under Optomap UWFI (Daytona, Optos, UK). Mydriatic standard and eye-steering UWFI was captured in central gaze and four different peripheral gazes. Sensitivity of detecting peripheral retinal lesions under different UWFI settings was compared.

Results

141 (64.09%) eyes were with peripheral retinal lesions. The sensitivity for detecting peripheral lesions from low to high was 41.84% (95% CI 33.62% to 50.54%) under non-mydriatic standard UWFI setting, 52.48% (95% CI 44.08% to 60.75%) under mydriatic standard setting, 75.18% (95% CI 67.21% to 82.06%) under non-mydriatic eye-steering setting and 86.52% (95% CI 79.76% to 91.69%) under mydriatic eye-steering setting. Both mydriasis and eye-steering technique increased sensitivity of detecting peripheral lesions with statistical significance (p<0.001). By applying eye-steering technique, sensitivity of detecting lesions located in superior and inferior quadrants witnessed a greater increase compared with other two quadrants (p<0.05). Neither spherical equivalence (p>0.05) nor axial length (p>0.05) was an independent influence factor for detecting peripheral lesions.

Conclusions

Eye-steering technique and mydriasis could both efficiently improve the sensitivity of detecting peripheral retinal lesions in myopic patients. Lesions of superior and inferior quadrants benefited more from eye-steering technique.
Are young military personnel at a disproportional risk of heat illness?
Authors: Ogden Henry B , Rawcliffe A J , Delves S K , Roberts A
Published: March 2022

Heat illnesses (HI) define a continuum of conditions where patients become incapacitated due to uncompensable heat stress. In the military, HI has a significant health, financial and operational burden that requires vigilant management. Military training and operations regularly expose personnel to known HI risk factors, meaning that prevalence remains high despite stringent attempts to reduce risk to as low as reasonably practicable. While prepubertal children and elderly adults are widely demonstrated to be at greater risk of classic HI than young adults due to impaired physiological and/or behavioural thermoregulation, in military personnel, it is young recruit-age individuals (16–19 years) who consistently experience the highest prevalence of exertional HI. Mechanistically, controlled laboratory studies have never directly compared thermoregulation between young recruit-age individuals and other groups of adults, though research highlighting impaired thermoregulation in prepubertal children potentially has some relevance to late-developing young recruit-age personnel. Aside from potential age-related differences in thermoregulation, a major consideration must also be given to the increased prevalence of organisational risk factors for HI in younger military personnel (eg, education, physical load, rank, job roles), which is likely to be the primary explanation behind age-related trends in HI prevalence, at least in the military. The aims of this article are to review: (i) the epidemiology of HI between young recruit-age individuals and older military personnel; (ii) the theoretical basis for age-associated differences in thermoregulatory function and (iii) pertinent areas for future research.
Evaluating interventions to improve ethical decision making in clinical practice: a review of the literature and reflections on the challenges posed
Authors: Ignatowicz Agnieszka , Slowther Anne Marie , Bassford Christopher , Griffiths Frances , Johnson Samantha , Rees Karen
Published: March 2022

Since the 1980s, there has been an increasing acknowledgement of the importance of recognising the ethical dimension of clinical decision-making. Medical professional regulatory authorities in some countries now include ethical knowledge and practice in their required competencies for undergraduate and post graduate medical training. Educational interventions and clinical ethics support services have been developed to support and improve ethical decision making in clinical practice, but research evaluating the effectiveness of these interventions has been limited. We undertook a systematic review of the published literature on measures or models of evaluation used to assess the impact of interventions to improve ethical decision making in clinical care. We identified a range of measures to evaluate educational interventions, and one tool used to evaluate a clinical ethics support intervention. Most measures did not evaluate the key impact of interest, that is the quality of ethical decision making in real-world clinical practice. We describe the results of our review and reflect on the challenges of assessing ethical decision making in clinical practice that face both developers of educational and support interventions and the regulatory organisations that set and assess competency standards.
Getting there together: highlights, challenges and opportunities for tobacco control in the Oceania region
Authors: Gifford Heather , Tautolo El-Shadan , McCool Judith P , Gartner Coral E , Edwards Richard , Maddox Raglan
Published: March 2022

Background

The paper focuses on the geographical region of Oceania. We highlight the tobacco control leadership demonstrated in this region and describe the challenges and opportunities to achieving country-specific smoke-free goals.

Results

Significant achievements include smoke-free nation goals, world-leading initiatives such as plain packaging, and a bold plan by New Zealand to reduce the retail availability of smoked tobacco products and remove virtually all the nicotine from cigarettes and rolling tobacco. There are significant challenges and opportunities before reaching smoke-free status including implementation pathways requiring strong governance and leadership and compliance monitoring and enforcement.

Conclusions

We conclude that achieving a smoke-free Oceania is possible through already existing bold country and regional smoke-free goals, excellent tobacco control leadership, experience and resources, and an understanding of how to work collectively. However, a commitment to focus tobacco control efforts regionally is required to achieve a smoke-free Oceania together.