Ball Type Research Articles

Determining the tactical and technical level of competitive tennis players using a competency model: a systematic review.

The aim of this systematic review is to provide an evidence-based synthesis of the literature on the topic of technical and tactical competencies of tennis players and to answer the following research questions: (1) What is the state of the art of research on technical and tactical competencies (i.e., skills and knowledge) and tennis; (2) What are the most important topics related to technical and tactical competencies in tennis players. Electronic searches were conducted in Web of Science, PubMED and SPORTDiscus (August to September 2023). This systematic review was conducted in accordance with PRISMA guidelines. To reduce risk, all published literature was searched and primary studies were included. The search terms included skills or competencies, match or play, player and tennis and excluded studies on non-competitive tennis players-notation analysis, AI method, systematic review and validation of tools. Of the 390 publications found in these searches, 13 articles were considered relevant and included in this study. They were divided into three categories: (1) technical-tactical skills, (2) match situations and (3) match performance. There was clear evidence that there is a test instrument for analyzing tactical-technical skills that has sufficient reliability and validity and is of practical value to tennis coaches. The development of tactical-technical skills is influenced by method (variability between/within skills), conditions (court size, ball type) and areas of development (situational awareness, anticipation, decision making). There are differences in match and stroke performance between different quality groups (professionals, juniors), which can also be influenced by mental strength. For a comprehensive study of tennis players' abilities, the use of modern technologies is possible and necessary in the future. Future research should focus on the creation of competency models for the playing level of tennis players, which could include at least three key elements: (1) key competencies, (2) description of standards, (3) evidence.

Ball type (4-(tert-butyl)-1,2-phenylene)dimethanolate bridged dinuclear metallo phthalocyanines: Synthesis, characterization, electrochemistry, and in situ spectroelectrochemistry

In this research, cofacial ball type metallo phthalocyanines (MPcs) with a longer bridge, which by adding a –CH2 group to the oxo bridge, were obtained by working the 4,4′-(((4-(tert-butyl)-1,2-phenylene)bis(methylene))bis(oxy))diphthalonitrile beginning complex. Molecular characterizations of the starting compound and dinuclear ball-type MPcs (Co, Fe, Mn, Zn, Ni) obtained from it were made using elemental analysis, 1H-NMR, 13C-NMR, FT-IR, UV–Vis, and MALDI-TOF mass spectroscopy. In addition, how the macromolecule’s spectral, electrochemical, in situ spectroelectrochemical, and electrochromic properties changed was investigated when the phthalocyanine (Pc) rings moved away from each other due to the increasing linking bridge length. The electrochemical properties of ball-type Pcs were investigated via Cyclic Voltammetry (CV) and Square Wave Voltammetry (SWV) in the non-aqueous solvent system on a Pt working electrode (WE). In situ spectroelectrochemical measurements also were carried out to support the electrochemical measurements. In situ electrocolorimetric techniques revealed color changes relevant to the redox processes. Electrochemical and spectroelectrochemical measurements showed that ball type metallo-Pcs form steadfast mixed-valence species based on metal and/or Pc ring on account of the fact that there are forceful and striking intramolecular interactions between the two Pc segments. As a result of the cofacial molecular structure of ball type metallo-Pcs and the split molecular orbitals, the complexes have rich redox properties. They can be utilized as a material in electrochemical technologies since they have plentiful redox behaviors. In situ spectroelectrochemical and in situ electrocolorimetric measurements demonstrated that they also have rich spectral and chromatic features. Due to the apparent color and spectral variations, they are appropriate for electrochromic appliances.

New Technique of Glenohumeral Joint Dissection

Objectives: Glenohumeral is a ball and socket type of synovial joint which permits a wide range of movement. During the typical shoulder joint dissection, we are unable to see the intracapsular view of shoulder joint. Methods: A dissection technique that was performed in Sharir Rachana Dept. of NIA, Jaipur, which exposes the glenohumeral joint's internal capsule, the glenoid labrum, the proximal insertion of the long head of the biceps tendon, and the surfaces of the joint while protecting the posterior aspect of the capsule and the surrounding muscles and tendons that support the joint. Results: This new dissection method allowed the preservation of glenohumeral joint structures and provides a better understanding of its intracapsular view and related structures. Conclusion: The glenohumeral joint can be dissected using this new technique, by which we can prevent the damage to the structures that surround it and enabling visualization of its intracapsular view.

Deep Rolling of Al6061-T6 Material and Performance Evaluation with New Type Designed WNMG Formed Rolling Tool

In deep rolling, ball and roller type burnishing tools are generally used. It is generally difficult to deep roll contours with curved and conical shapes with the existing rolling tools. The aim of this study is to design experiments with a roller insert that will be an alternative to deep rolling inserts being used now and that can be fixed on the present tool holders; and to investigate the usability of them including curve and conical formed workpieces with the help of this designed tool. For this purpose, a spherical insert with a radius of 1 mm in the form of WNMG was designed based on the WNMG insert model and used in deep rolling of Al6061-T6 material using different forms and parameters. 143, 330, 495 N rolling force, 0.04, 0.08, 0.12 mm/rev feed and 400, 600, 800 rpm spindle speed were selected as rolling parameters. By examining the microhardness and surface structure of deep-rolled Al6061 parts, the achievability of the results of existing tools in deep rolling was investigated. At the end of the study, it was determined that the new type of rolling tool produced results similar to the existing tools in deep rolling in terms of microhardness and surface morphology, which enabled that the workpieces with curve and conical forms could also be rolled, and that this rolling tool could be used as an alternative in deep rolling.

Effects of Increasing Pitch Count on Pitch Type Ball Metrics and Release Height in High School Softball Pitchers.

Softball research has investigated changes in physical characteristics, mechanics, and ball speed as elements of fatigue. However, the influence of pitch volume on ball metrics is unclear. The purpose of this study was to investigate the influence of pitch volume on ball performance and release metrics in softball pitchers across different pitch types. As pitch volume increased, there would be a decrease in ball metrics of the fastball and changes in breaking pitches would be observed earlier than the fastball or changeup. Descriptive laboratory study. Level 5. A total of 21 (15.4 ± 1.6 years; 1.6 ± 0.2 m; 76.0 ± 17.2 kg) softball pitchers participated. Procedures consisted of participants pitching a simulated game consisting of 100 pitches, taking a 30-minute break, and then throwing 12 pitches to simulate the first inning of a doubleheader. Participants randomly threw each pitch type (fastball, changeup, curveball, or dropball). Ball performance and release metrics were measured using a Rapsodo portable pitch tracker. A 3 (time) by 4 (pitch type) multivariate analysis of variance revealed that pitch speed was significantly higher in the first inning compared with the last inning and the doubleheader inning. The fastball, curveball, and dropball revealed a significant difference in pitch speed between timepoints. Specifically, the curveball and dropball first-inning pitch speed was significantly greater than the last and doubleheader inning. Alternatively, the fastball had a significant increase in pitch speed from the last inning to the doubleheader inning. The typical 30-minute break given between games for doubleheaders may be sufficient recovery time for the fastball but not for the curveball and dropball. The Rapsodo device is an accessible method of tracking ball performance and pitch release metrics and could be helpful in identifying when a pitcher may be experiencing performance detriments in response to increasing pitch count.

Effect of grinding conditions on oil shale surface: FTIR analysis

Grinding is an indispensable process in many industrial plants. Nonetheless, the ground products may pass through the surface and/or undergo structural changes that may affect subsequent processes. In this study, the changes in the oil shale surface during its dry grinding in a ball mill were followed by Fourier-transform infrared (FTIR) analysis under different grinding conditions such as grinding time, ball type (i.e. ceramic or steel), and number of balls. Moreover, the generated heat limits during grinding were revealed by correlating the change in surface function groups of the ground products with those of conventionally heated oil shale samples in a furnace. The results indicated that the more intense the grinding action, in terms of the number or size of grinding balls and the grinding time, the higher the variations in the ground products’ FTIR spectra, indicating the higher the surface oxidation of oil shale. More interestingly, correlating the FTIR spectra of the heated samples with those of the ground products indicated that the temperature inside the mill does not exceed 150 °C.

An In Vitro Study regarding the Wear of Composite Materials Following the Use of Dental Bleaching Protocols.

Composite materials used in dental restorations are considered resistant, long-lasting and aesthetic. As the wear of restorations is an important element in long-term use, the aim of this study was to evaluate the surface condition of nanohybrid and microfilled composite resins, after being subjected to the erosive action of dental bleaching protocols. This paper reflects a comparative study between one nanofilled composite and three microfilled composites used in restorations. For each composite, three sets of samples (under the form of composite discs) were created: a control group, an "office bleach" group with discs bleached with 40% hydrogen peroxide gel, and a "home bleach" group with discs bleached with 16% carbamide peroxide gel. Wear was numerically determined as the trace and the coefficients of friction obtained using a tribometer, the ball-on-disk test method, and two balls: alumina and sapphire. For all composite groups, there were statistically significant differences between the wear corresponding to the control and bleaching groups, for both testing balls. Regarding the composite type, the largest traces were recorded for GC Gradia direct anterior, for all groups, using the alumina ball. In contrast, for the sapphire ball, 3M ESPE Filtek Z550 was characterized by the largest traces. With respect to the friction coefficients, the "office bleach" group recorded the largest values, no matter the composite or the ball type used. The 3M ESPE Valux Plus composite recorded the largest friction coefficients for the alumina ball, and 3M ESPE Filtek Z550 for the sapphire ball. Overall, the "office bleach" group was characterized by higher composite wear, compared to the "home bleach" protocol or control group. Nanofilled composite resins showed superior wear resistance to microfilled resins after undergoing a bleaching protocol.

Evaluation of computed tomography metal artifact and CyberKnife fiducial recognition for novel size fiducial markers.

This study aimed to compare fiducial markers used in CyberKnife treatment in terms of metal artifact intensity observed in CT images and fiducial recognition in the CyberKnife system affected by patient body thickness and type of marker. Five markers, ACCULOC 0.9mm×3mm, Ball type Gold Anchor (GA) 0.28mm×10mm, 0.28mm×20mm, and novel size GA 0.4mm×10mm, 0.4mm×20mm were evaluated. To evaluate metal artifacts of CT images, two types of CT images of water-equivalent gels with each marker were acquired using Aquilion LB CT scanner, one applied SEMAR (SEMAR-on) and the other did not apply this technique (SEMAR-off). The evaluation metric of artifact intensity (MSD ) which represents a variation of CT values were compared for each marker. Next, 5, 15, and 20cm thickness of Tough Water (TW) was placed on the gel under the condition of overlapping the vertebral phantom in the Target Locating System, and the live image of each marker was acquired to compare fiducial recognition. The mean MSD of SEMAR-off was 78.80, 74.50, 97.25, 83.29, and 149.64 HU for ACCULOC, GA0.28mm×10mm, 20mm, and 0.40mm×10mm, 20mm, respectively. In the same manner, that of SEMAR-on was 23.52, 20.26, 26.76, 24.89, and 33.96 HU, respectively. Fiducial recognition decreased in the order of 5, 15, and 20cm thickness, and GA 0.4×20mm showed the best recognition at thickness of 20cm TW. We demonstrated the potential to reduce metal artifacts in the CT image to the same level for all the markers we evaluated by applying SEMAR. Additionally, the fiducial recognition of each marker may vary depending on the thickness of the patient's body. Particularly, we showed that GA 0.40×20mm may have more optimal recognition for CyberKnife treatment in cases of high bodily thickness in comparison to the other markers.

Exploring the influence of task and environmental constraints on batting and bowling performance in cricket: A systematic review

Cricket is an unique international sport where environmental and task constraints have shown to have a significant impact on batting and bowling performance. The aim of this systematic review was to determine the effect of task and environmental constraints on cricket performance. A systematic literature search was conducted across Scopus, PubMed, Web of Science, CINAHL, and SportDiscus. Studies were deemed eligible if they reported the effects of pitch type, pitch length, equipment (e.g. cricket bat, batting pads, ball type, etc.) on cricket performance. A total of 20 studies met the inclusion criteria with Kmet score ranging between 75% and 92%. The results from this study demonstrate that environmental constraints such as pitch-type and task constraints such as equipment modification (e.g. type of cricket bat, batting pads, ball) and pitch length can influence cricketer's batting and bowling performance. Scaling cricket bats and reducing pitch length were acutely beneficial to cricket batting, while ball type, pitch length and soil properties were impactful on bowling performance. Importantly though, the impact of constraint manipulation seemed to be influenced by the skill level of the performer. The findings from this study may help to inform coaches and practitioners improve skill acquisition, through constraint manipulation, to develop highly adaptive cricket batting and bowling skill.

Quantum healthcare computing using precision based granular approach

Previously, doctors interpreted diseases and their outcomes according to their experience in diagnosis. However, with the rapid increase in technology and population, the task of examining the patient becomes cumbersome and sometimes human efforts produce inconsistent results. Several research is being done for healthcare in terms of improving visualization and accuracy by using machine learning models. The current research targets to explore quantum computing as a different way of processing information compared to classical computer systems such as the use of quantum bits (qubits) along with superposition and entanglement for extending the computation capabilities at an unprecedented level of thinking in the healthcare domain. Quantum computing systems provide exponential benefits in terms of high-speed processing, faster and easier diagnostic assistance, unimaginable reduction in processing throughput, and many more. An extensive comparative analysis of existing approaches has been made which benchmarks the need for quantum healthcare computing. The objective of this work is to interpret whether Quantum computers prove to be more trusted when it comes to patient diagnosis, and faster analysis leading to cost optimization. In order to accelerate patient diagnosis, different approaches have been presented. The authors have proposed a precision-based granular approach for patient diagnosis that incorporates diagnosing the disease with enhanced precision and granularity. It involves reporting symptoms by the patient, encountering by healthcare expert on multiple factors, precise examination, granular health status (understanding past and present medical history), followed by a precise intervention by understanding biomolecular simulations. The algorithm has been presented to describe the flow process for patient diagnosis modeling using quantum computing. It involves qubits initialization, pairing the values, assigning probabilistic values, cross-validation, and quantum circuit formation. Precision-based granular approach has been implemented for a scenario (consisting of medical parameters such as oxygen and heart rate level, with the functionality of diagnosing oxygen level and heart range which lies as either normal or not normal (high/low)). Precision-based granular approach deals specifically with the individual ‘biomolecular simulation by understanding variations in the individual body whereas the umbrella-based approach does not deal with specifically to individual mechanisms. Granular level of encounter is not possible in umbrella-based treatment. Python Jupyter notebook and IBM Composer tool is used for the implementation of results. Bloch sphere and computational state graph are obtained as an output for better visualization and understanding. Falcon r5.11H processor is used with the version of 1.0.24 of IBM Composer to simulate the experiment. The methodology using precision based granular approach provides timely encounter of disease along with umbrella diagnosis and precise treatment. The time is taken and frequency of qubits have been presented with promising results. The diagnosis process and optimizing cost efficiency can aid in an early detection of the disease.

Parametric study on four station ball mill for synthesis of ultrafine powders

One of the most common approaches to creating ultrafine materials is ball milling. Among the various types of ball mills, planetary ball mills are widely used by the research community. A planetary type ball mill is economical, simple to operate, and ideally suited for small-quantity batch type synthesis of powders and alloys and for reactive processing of powders. The size of the jar and balls, rotational speed, milling duration, ball-to-powder ratio, jar material, milled material, and temperature are the most important process factors in ball milling. Temperature was determined with the help of non-contact temperature measuring device. The rate of grain size reduction and the minimum grain size that can be achieved for a given powder material depend on the above parameters. A huge number of tests would be needed to find the optimal values for the approximately ten process parameters with interaction effects. As part of this research effort, a Taguchi Design of Experiments (DOE) approach was adopted to determine the optimum process parameters to obtain the fine grain sizes for iron, cobalt, and nickel powders. Although the ball-to-powder ratio and ball milling time each have around a 20–25% impact on the grain size reduction rate, ball milling speed has almost a 48% impact. The powders were characterised for grain size using an x-ray diffraction technique, and the powder morphology was studied using a scanning electron microscope.

Electrochemical properties of the CaNi4.8M0.2(MMg, Zn, and Mn) mechanical milling alloys used as anode materials in nickel‐metal hydride batteries

AbstractThe present research work examines the electrochemical properties of CaNi4.8M0.2(MMg, Zn) type alloy applied as an anode in nickel metal hybrid batteries. Based on an extensive study of the CaNi4.8Mn0.2 compound prepared by mecano‐synthesis; under an argon atmosphere, with a variation of milling time and weigh ratio, using a Retsch PM400 type ball mill. The experimental results show that the excellent electrochemical properties were obtained for a milling time of 40 h and a ball‐to‐powder weight ratio equal to 8:1. Based on this study, we examined electrochemically the CaNi4.8M0.2(MMg, Zn, and Mn) compound according to the optimized parameters. Several methods, such as galvanostatic polarization and potentiodynamic polarization, were applied to characterize these electrodes. CaNi4.8M0.2(MMg, Zn, and Mn) electrodes were activated, respectively, during the first, second, and third cycles. The maximum discharge capacity was about 87, 60, and 96 mAhg−1 at ambient temperature. These electrochemical findings correlate with the kinetic results provided during a long cycle.

In Medias Res

In Medias Res Ross Berger (bio) EAST COAST CONNECTION I grew up in a rural suburb of Hartford, Connecticut, about 35 miles away from Philip Roth's home in Warren. Charlotte Hungerford, in nearby Torrington, served as Roth's hospital for standard care for a better part of four decades. I was born there in the 1970s. Warren is located in Litchfield County, the northwest section of Connecticut, known for its remote beauty and two-hour drive to Manhattan. The latter, along with the area's woodsy calm, is why it has been a popular residential destination for many luminaries in the performing arts and literature, including Meryl Streep, Mia Farrow, Arthur Miller, William Styron, and Terrence McNally. Roth's name would be included among this list when proud Litchfield County residents rattled off its bona fides: "Bucolic and peaceful…" "Home to the first American law school…" "Plenty of celebs including…" I never once saw Philip Roth when I set foot in Litchfield County, and believe me, I was on the lookout in my early twenties whenever I was on break from college or grad school. But he was a man who protected his privacy dearly, so I tempered my expectations—eliminated them actually, as I was accustomed to doing (more about this later). I'd like to think I spotted him in person one Saturday evening in July 2000, among an exodus of participants of Midsummer Night Swing, a weekly summer-long "outdoor dance party" at Lincoln Center. The glut of people around me made it impossible to verify. Perhaps it was a random accountant who bore a resemblance to the great author. Or maybe it was Moishe Pipik, Roth's fictional doppelgänger from Operation: Shylock. Or maybe—no: likely—it was just wishful thinking. For a couple of years after that evening, I had tried to draw connections to Roth any way that I could, but to no avail. I didn't know anyone who went to Bucknell or University of Chicago in or around the time he did. And I had no publishing network to speak of. [End Page 119] The closest I got, which is not close at all, is my New Jersey story—a slight echo of American Pastoral through my mother, a native of Trenton. Her brother, my uncle, was a high school athletic star and war veteran just like American Pastoral's Swede Levov, who once hailed from a city bigger than Trenton—Newark. My uncle was slightly younger and served not in Korea like the Swede, but in a different conflict in the Pacific (Vietnam). Both were Jewish, physical, mythic. Both married non-Jews. Both could assimilate in either Jewish or gentile crowds, and, in either, be idolized and accepted as one of their own. Alas, these details are not unique or special in America's most populated state per square foot. It's just that American Pastoral is a deeply relatable fiction. If I must admit the obvious, my true connection to Roth has been as a reader. In this role, I found consolation as a student dealing with the long aftermath of a family tragedy and, once more, as a young writer in need of basic guidance. During each of these times, Roth served as a comforting sage-on-the-page, whose words were radar through the fog of trauma. WORDS OF HEALING I came to Roth's work after an on-again-off-again journey of reading Saul Bellow in my mid-to-late teenage years. It started when I studied Henderson the Rain King for a term paper in my tenth grade American Literature class. From a list of authors typed likely on an IBM Selectric (this was 1992, mind you, well past the era of the typewriter), I chose Bellow because of two descriptors next to his name: "Jewish" and "Nobel Prize-winning." (Admittedly, the former was the bigger enticement after months of reading nineteenth-century works with strong Christian overtones and Lost Generation novels rife with anti-Semitism.) I did not take to Henderson the Rain King. Finding it too tame and, at times, culturally exploitative, I moved on to Dangling Man and Seize the...

Orthonormal System for a Matrix Ball of the Second Type $\mathbb B_{m,n}^{(2)}$ and Its Skeleton (Shilov's Boundary) $\mathbb X_{m,n}^{(2)}$

Orthonormal System for a Matrix Ball of the Second Type $\mathbb B_{m,n}^{(2)}$ and Its Skeleton (Shilov's Boundary) $\mathbb X_{m,n}^{(2)}$

振動台実験による剛体球式感震器搭載ガスメーターの地震応答時における遮断特性の評価

Following earthquakes, it is essential to immediately assess the damage sustained in buildings and make judgments about the safety of their reoccupation. As instrumenting buildings with accelerometers is expensive, damage assessments are primarily done by entering the building and performing visual observations. As an alternative, the emergency gas shut-off feature available in gas meters installed in buildings is considered as a potentially effective indicator for identifying damage in structures. In this study, the commonly used gas meters equipped with `rigid ball type seismic sensor' are subjected to earthquake demands via shake-table testing to evaluate the shut-off characteristics.

Estimating the stability of steady motion of vibration machines operating on the somerfeld effect using an empirical method

One-, two-, and three-mass vibration machines with translational motion of platforms and a vibration exciter of a ball, roller, or pendulum type with several loads were studied. The empirical criterion for the onset of auto-balancing was applied in the extended formulation. It has been established that a single-mass vibration machine has one resonant speed, and: – at the after-resonance speeds of rotation of loads synchronously with the rotor, the auto-balancing mode becomes stable; – at the pre-resonance speeds of rotation of loads, loads tend to gather together. In a dual-mass vibration machine, there are two resonant speeds and one additional speed located between two resonant ones. The auto-balancing mode is stable when the loads rotate synchronously with the rotor at the following speeds: – between the first resonant speed and the additional speed; – greater than the second resonant speed. At other speeds of rotation of loads, loads tend to gather together. The three-mass vibration machine has three resonant speeds and two additional speeds, located one by one between adjacent resonant speeds. The auto-balancing mode is stable when the loads rotate synchronously with the rotor at the following speeds: – between the first resonant speed and the first additional speed; – between the second resonant speed and the second additional speed; – greater than the third resonant speed. At other speeds of rotation of loads, loads tend to gather together. In a single-mass vibration machine, the value of the resonant speed does not depend on the viscosity of supports. In dual-mass and three-mass vibration machines, all characteristic speeds depend on the viscosity of supports. With small forces of viscous resistance, the values of these speeds are close to the characteristic speeds found in the absence of resistance forces.

Does the New Resin-Free Molten d60 Ball Have an Impact on the Velocity and Accuracy of Handball Throws?

The aims of this study were (i) to examine gender differences between the Molten H3X5000 ball and the resin-free Molten d60 ball with regard to throwing velocity and accuracy according to two conditions, throwing situation and instruction received, and (ii) to analyse the player’s subjective perception on throwing velocity according to ball types. The sample comprised 29 handball players (18 men and 11 women), who carried out a throwing protocol to measure velocity, accuracy, and subjective perception. The main results found significant throwing velocity differences between the new balls and traditional balls with resin in short-distance actions (7 m). Specifically, males did not perceive a loss of throwing velocity with the new ball. For target accuracy, men showed higher velocities with the traditional balls with resin and new balls than with the traditional balls with no resin. Women reached higher velocities with the new balls and the traditional balls with resin than with the traditional balls with no resin. Furthermore, throwing accuracy and effectiveness were not influenced by the ball type or throwing distance. While uneven results in relation to throwing velocity according to ball type, gender, and throwing distance were identified, the accuracy and effectiveness were not affected by the ball type. As the throws were made from further away (9 m), the impact of the new ball on the throwing velocity decreased.

With or without replacement? Sampling uncertainty in Shepp’s urn scheme

AbstractWe introduce a variant of Shepp’s classical urn problem in which the optimal stopper does not know whether sampling from the urn is done with or without replacement. By considering the problem’s continuous-time analog, we provide bounds on the value function and, in the case of a balanced urn (with an equal number of each ball type), an explicit solution is found. Surprisingly, the optimal strategy for the balanced urn is the same as in the classical urn problem. However, the expected value upon stopping is lower due to the additional uncertainty present.

FEPPCON XI: Powering Global Progress

In June 2022, the IEEE Power Electronics Society (PELS) held its eleventh biannual long-term strategic outlook meeting the Future of Electronic Power Processing and Conversion (FEPPCON XI) in Reykjavik, Iceland ( <xref ref-type="fig" rid="fig1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Figure 1</xref> ). FEPPCON XI was postponed by one year from 2021 due to the global pandemic to allow a face-to-face meeting. Most invited participants were able to attend in person. In plain vernacular, FEPPCON is a forward-looking, crystal ball type of meeting of invited participants to assist PELS foresee where power electronics technologies and applications are heading over the next 5–10 years so that the Society can best position itself in terms of organization, programs, and member services to meet those emerging and growing elements of the field.

Determining experimentally the patterns of the manifestation of the Sommerfeld effect in a ball auto-balancer

This paper proposes an experimental method for studying the Sommerfeld effect in auto-balancers or exciters of resonant vibrations of pendulum, ball, or roller type. The method is based on the processing of signals acquired from analog sensors of rotations and vibration acceleration using regression analysis. The method is tested on a specially designed rotor bench on isotropic viscoelastic supports, which executes spatial motion, and an auto-balancer with one ball. Checking the accuracy of the method using stroboscopic lighting demonstrates the accuracy of determining the speed of rotation of the rotor, ball, oscillation frequency of the rotor, etc. with an error of several hundredths of a percent. When fixing the ball relative to the rotor, a classic inertial vibration exciter is obtained. The rotor has two resonant velocities. The Sommerfeld effect is almost not manifested. With a gradual increase in the frequency of the current, the rotor speed increases monotonously. There is no significant slip or jump in the rotor speed. There are two distinct peaks on the amplitude-frequency characteristic. Therefore, such a vibration exciter is not suitable for the excitation of resonant vibrations. With the free placement of the ball in the oil, the behavior of the system changes significantly in the vicinity of the first resonant velocity. The first narrow resonant peak disappears in the roto. Instead, there is a long, gentle resonant rise. It lasts at a current frequency of 9.4 Hz to 19.3 Hz. The amplitude at the reference point on the resonant rise increases from 0.7 mm to 2.84 mm. Therefore, by changing the frequency of the current, it is possible to smoothly change the amplitude of the rotor oscillations by almost 4 times. The maximum amplitude of rotor oscillations is the same as at the first resonance with a fixed ball. Due to the gentleness of the resonant rise, a freely installed ball itself is a reliable exciter of resonant vibrations