Small Ball Research Articles

The set of intersections of several independent Brownian motions on Carnot group

In this paper the existence of intersections for functions of several Brownian motions on the Carnot group is studied. A condition is presented for the existence of such intersections with Probability 1, which is in the form of the asymptotics of a measure on a specific family of small balls. The measure is arbitrary but can be chosen as a surface measure on the manifold related to intersections, and the balls are constructed using the distances related to the processes. Additionally, if the same condition holds in a weaker form, it is shown that there is a Hausdorff measure, such that the value of this Hausdorff measure on the set of intersection points is finite with Probability 1.

Are gel blasters a safe toy? A study into their kinetic energy per unit area

Gel blasters are currently imported and marketed as children’s toys in Australia. Gel blasters closely imitate the appearance of many genuine firearms of all types and are designed to propel small hydrated gel balls of approximately 7–8 mm in diameter, by means of compressed air or gas. They are considered illegal in all states of Australia except Queensland but these items aren’t specifically written into most state firearms legislation. However, to be considered as children’s toys, they must not exceed the recommended kinetic energy (KE) of 2500 J/m2 as outlined in the Australian/New Zealand Standard Safety of Toys – Part 1: Safety aspects related to mechanical and physical properties (Safety of Toys ASNZS ISO 8124.1:2019) [1]. The aim of this study was to determine if a range of gel blasters would conform to the Australian & New Zealand Standard and have projectiles with kinetic energy of less than 2500 J/m2. Utilising the testing procedure outlined in ASNZS ISO 8124.1:2019 (Australian/New Zealand Standard Safety of Toys – Part 1: Safety Aspects related to Mechanical and Physical Properties (Safety of Toys ASNZS ISO 8124.1:2019) [1]), a range of gel blasters were tested. In addition, a number of NERF™ toys and airsoft firearms were tested to provide reference between an accepted child’s toy and items considered to be a firearm, such as airsoft firearms. A NERF™ toy (commonly referred to as a blaster) fires a foam projectile at very low velocities through direct spring/striker impact to the rear of the dart, battery-powered motorised flywheel, or by compressed air generated by a small piston inside a cylinder. Airsoft firearms are designed to fire hard plastic balls (typically 6 mm in diameter) and can achieve velocities upwards of 90 m/s with the potential to cause injuries to soft tissue. Results showed the KE per unit area of pellets fired from airsoft firearms significantly exceeded the recommended 2500 J/m2 ranging from approximately 10,620 J/m2 to 69,650 J/m2. Twenty of the twenty-four gel blasters tested (83 %) exceeded 2500 J/m2, with values ranging between 2112 J/m2 and 42,645 J/m2. NERF™ toys were found to be notably under 2500 J/m2, ranging from approximately 1230 J/m2 to 2129 J/m2. The results suggest that the majority of gel blasters (items of seizures) tested, currently being imported and marketed as children’s toys in Australia, easily exceed 2500 J/m2 as outlined in the ASNZS ISO 8124.1:2019 and are not safe to be marketed and sold as children’s toys. Reinforcing the position of most jurisdictions, the Australian Federal Police (AFP) in Canberra made the following statement in 2019: ‘ACT (Australian Capital Territory) Policing is reminding the public that replica firearms known as gel blasters are illegal in the ACT’. Taking the results determined throughout this research and the statement by AFP into consideration, gel blasters should not be exempt from control under Firearms Legislation because they are claimed to be toy.

How the Science Behind Video Games Helps Kids Walk

Did you know that some of the same technology used to make video games and movie special effects can help scientists better understand human movement? During motion capture, also called mocap, small reflective balls, or markers as they are called, are placed on specific points of a person’s body. Mocap systems work using multiple cameras around the room that track the motion of the markers as a person walks, runs, jumps, or plays. The information gathered during mocap can be used to help doctors decide the best possible care to improve a child’s walking. It can also be used to determine when someone is ready to go back to sports after an injury, to help prevent people from getting injuries in the first place, or to improve their sports performance.

Contribution Of Hand Reaction Speed And Feet Movement Speed With Table Tennis Playing Skills

Table tennis is a very unique type of small ball game. This is because table tennis uses a small ball made of celluloid, lightweight, and uses a bat to hit. This game is played on a table bounded by a net at the center of the table. The purpose of this study was to determine the contribution of hand reaction speed and footwork speed to playing tennis skills. This research belongs to the type of descriptive correlational research using a population of all male students state high school 1Marioriawa Soppeng Regency with a total sample of 40 people selected by random sampling. The data analysis technique used is the correlation analysis technique using the SPSS version 22.00 system at a significant level of 95% or 0.05. Starting from the results of data analysis, this study concludes that: (1) Hand reaction speed has a contribution to playing tennis skills by 61.6%; (2) Footwork speed has a contribution to the skills of playing tennis by 72.4%; and (3) Hand reaction speed and footwork speed have a contribution to the skill of playing tennis by 73.9%.

Tunable rebound of millimeter-sized rigid balls by magnetic actuation of elastomer-based surface microstructures

A novel method for controlling the rebound behavior of small balls made of Al2O3 with a radius of 2.381 mm is presented. It uses different types of micro-structured surfaces of soft magnetoactive elastomers. These surfaces were fabricated via laser micromachining and include fully ablated surfaces as well as micrometer-sized lamellas with a fixed width of 90 µm, height of 250 µm and three different gap sizes (15, 60 and 105 µm). The lamellas can change their orientation from edge-on to face-on configuration according to the direction of the external magnetic field from a permanent magnet. The orientation of the external magnetic field significantly influences the rebound behavior of the balls, from a coefficient of restitution e of ≈0.5 to < 0.1. The highest relative change in the coefficient of restitution between zero field and face-on configuration of ≈80% is observed for lamellas with a gap of 60 µm. Other characteristics of the ball rebound such as the penetration depth into an Magnetoactive elastomer and the maximum deceleration are investigated as well. The proposed method does not require a constant power supply due to the use of permanent magnets. It may find novel applications in the field of impact engineering.

Discriminant Analysis: the Influence of Exercise Modes on the Effectiveness of the Process of Learning to Throw A Small Ball for 9-Year-Old Boys

The purpose of the study is to determine the effect of the number of repetitions on the effectiveness of the process of learning to throw a small ball for 9-year-old boys. Materials and methods. The study involved 27 9-year-old boys, divided into three groups of 9 people in random order. Children and their parents were aware of all the features of the study and gave consent to participate in the experiment. The influence of the number of repetitions on the effectiveness of the process of learning to throw a small ball at a target in 9-year-old boys was studied. In a pedagogical experiment, the effect of 6, 12 and 18 repetitions with a rest interval of 60 s on the increase in the level of training in exercises of 9-year-old boys was studied. In the first group, boys repeated the task 6 times with a rest interval of 60 s, in the second group - 12 times with a rest interval of 60 s, in the third group 18 times with a rest interval of 60 s. In the process of teaching throwing exercises in a lesson, the level of training (“completed”, “failed to complete”) was assessed using an alternative method, and the probability of completing the exercise was calculated (p = n/m, where n is the number of successfully completed attempts, m is the total number of attempts). The method of algorithmic prescriptions was used in teaching 9-year-old boys. The transition to the next exercise was carried out after three successful attempts. Throwing a ball at a vertical target was studied. The research materials were processed in the statistical analysis program - IBM SPSS 20. In the process of discriminant analysis, a prognostic model for group membership was created. Results. Discriminant analysis made it possible to determine the influence of the number of repetitions on the effectiveness of developing the skills of throwing a small ball at a target; answer the question how reliably the repetition modes differ in terms of the effectiveness of the formation of motor skills, what class the object belongs to based on the discriminant values of the variables. Conclusions. Based on the analysis of group centroids, it was determined that 18 repetitions (6 sets of 3 times with a rest interval of 60 s) has a significant impact on the increase in the level of learning in physical education lessons. The group classification results show that 63.0% of the original grouped observations were correctly classified.

Thermal, microstructural, wettability and mechanical properties of Sn1.0Ag0.5Cu composite solder modified with Ti nanoparticles

In this study, highly active Ti nanoparticles (Ti NPs) were added to a low silver Sn-1.0Ag-0.5Cu (SAC105) solder. The thermal, microstructural, interfacial, wettability and mechanical properties of SAC105-xTi NPs (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 wt%) solders were investigated. The results showed that adding Ti NPs had little effect on the melting point and melting point range of SAC105 solder alloy. The solder alloy containing 0.2 wt% Ti NPs had the lowest coefficient of thermal expansion (CTE) of 21.1 × 10−6 m/°C. The SAC105–0.4 Ti NPs solder has a contact angle of 24.3°, 7.57° lower than the SAC105 solder. However, Ti NPs deteriorate the surface of the solder joint as they oxidize to produce TiO2 during the soldering process, resulting in a higher number of small solder balls precipitating from the surface of the joint. In addition, EPMA showed that Ti NPs adsorbed on the Cu6Sn5 grains, leading to changes in the morphology of the Cu6Sn5 grains and a decrease in the thickness of the IMC layer. The addition of Ti NPs had little effect on the mechanical properties of solder alloys. Excessive Ti NPs will agglomerate, leading to a sharp decrease in the shear strength of the solder joints.

DAT: A robust Discriminant Analysis-based Test of unimodality for unknown input distributions

This letter introduces a Discriminant Analysis-based unimodality Test (DAT) for automatically identifying whether a dataset is unimodal or multimodal, detecting deviations in time series datasets, estimating statistical parameters, and identifying the skewness of the data. DAT is effective in classifying datasets under both unimodal and multimodal conditions and is suitable for bi-classification applications. The performance of DAT was compared to two well-known unimodality tests, namely the dip and folding tests, and is shown to perform better. We then extended DAT to the development of a fault detection technique, which was tested against five different machine learning classifiers using data from the Case Western Reserve University (CWRU) ball bearing database. The results obtained show that the proposed approach is effective, achieving 99.999% accuracy for detecting small ball bearing fault sizes (0.007 inches). Our conclusion indicates a significant potential of the proposed test for improving anomaly detection in industrial and other related fields.

Some Remarks on Smooth Mappings of Hilbert and Banach Spaces and Their Local Convexity Property

We analyze smooth nonlinear mappings for Hilbert and Banach spaces that carry small balls to convex sets, provided that the radii of the balls are small enough. We focus on the study of new and mildly sufficient conditions for the nonlinear mapping of Hilbert and Banach spaces to be locally convex, and address a suitably reformulated local convexity problem analyzed within the Leray–Schauder homotopy method approach for Hilbert spaces, and within the Lipschitz smoothness condition for both Hilbert and Banach spaces. Some of the results presented in this work prove to be interesting and novel, even for finite-dimensional problems. Open problems related to the local convexity property for nonlinear mappings of Banach spaces are also formulated.

Expert Equestrians: How the Game of Polo Forged Masculinities in British India and the British Metropole, 1862–1914

ABSTRACT Polo is a team sport played on horseback hitting a small ball through the opposing team’s goal. In today’s form, it originated in Northern India and is an example of colonial encounter and the formation of colonial masculinities. This paper follows Mrinalini Sinha’s findings that see power at the centre of masculinity in arguing that the emerging dynamics between elite colonisers and colonised displayed in the game of polo aided both groups’ interest to rule. The late nineteenth century was defined by shifts in imperial social relations and the outdoors became a space to practice changes linked to racial, class, sex, ethnic, or national differences and discourses. Threatened not least by the emergence of Indian nationalism, British elite colonisers and Indian nobility played polo to assure each other of their social, cultural, and political power arrangement within a mostly homosocial milieu. In playing polo a cross-racial (elite) form of masculinity was practiced that allowed both groups to showcase their manliness and upkeep existing social hierarchies and status. After arriving in the metropole, polo turned into an even more elite form of masculinity to defend fragile class divides and reassure British upper classes of their status and privilege.

Impact detection method based on the ratio of mechanoluminescence intensity

This paper proposes an impact detection method based on the ratio of mechanoluminescence (ML) intensity, as an improvement over traditional methods that rely on absolute ML intensity. The study utilized two types of ML materials, ZnS:Cu2+ and ZnS:Mn2+, which were physically mixed and embedded them in polydimethylsiloxane (PDMS) to fabricate a flexible film sensor. A drop ball experimental setup was constructed, and the ML spectrum of the film sensor under the impact of a small ball was collected through a spectrometer. This established the relationship between impact velocity and the ratio of ML intensities. Experiments proved that the distance of spectral collection has a minimal effect on the measurement results of this method. Compared to traditional methods based on absolute ML intensity, this method has stronger resistance to environmental interference and better applicability. This new impact detection method based on the ratio of ML intensities has broad application prospects in future engineering applications, safety assessments, and material testing.

Using Discrete Element Method to Analyse the Drop Ball Test

The drop ball test (DBT) is a common quality control procedure used in many grinding media manufacturing units to evaluate the quality of manufactured balls. Whilst DBTs have provided reasonable data over many years, the quantitative comparison of the energy that the balls are subjected to during the DBT and in high-impact loading environments such as semi-autogenous grinding (SAG) mills remains a grey area. To that end, DBT experiments were conducted, and the discrete element method (DEM) was used to assess the grinding media collision behaviour and the extent of ball impact loading to determine the impact energy spectra of the ball collisions. The impact energy spectra data obtained were used to quantify the energy that the grinding balls are exposed to in the DBT environment. The results showed that larger balls were exposed to relatively higher energy levels and had a higher probability of fracture than smaller balls. Furthermore, early ball breakage in a grinding environment is mostly attributed to the existence of imperfections or pre-existing defaults within the ball, whilst continuous wear is a gradual consequence that deplete balls in the mill.

A reduction of the separability problem to SPC states in the filter normal form

It was recently suggested that a solution to the separability problem for states that remain positive under partial transpose composed with realignment (the so-called symmetric with positive coefficients states or simply SPC states) could shed light on entanglement in general. Here we show that such a solution would solve the problem completely.Given a state in $ \mathcal{M}_k\otimes\mathcal{M}_m$, we build a SPC state in $ \mathcal{M}_{k+m}\otimes\mathcal{M}_{k+m}$ with the same Schmidt number. It is known that this type of state can be put in the filter normal form retaining its type. A solution to the separability problem in $\mathcal{M}_k\otimes\mathcal{M}_m$ could be obtained by solving the same problem for SPC states in the filter normal form within $\mathcal{M}_{k+m}\otimes\mathcal{M}_{k+m}$. This SPC state can be built arbitrarily close to the orthogonal projection on the symmetric subspace of $ C^{k+m}\otimes C^{k+m}$. All the information required to understand entanglement in $ \mathcal{M}_s\otimes\mathcal{M}_t$ $(s+t\leq k+m)$ lies inside an arbitrarily small ball around that projection. We also show that the Schmidt number of any state $\gamma\in\mathcal{M}_n\otimes\mathcal{M}_n$ which commutes with the flip operator and lies inside a small ball around that projection cannot exceed $\lfloor\frac{n}{2}\rfloor$.

COACHING CLINIC OLAHRAGA TONNIS BAGI MAHASISWA STKIP MELAWI

This Community Service activity aims to introduce and deepen STKIP Melawi students' understanding of the game of tennis starting from equipment and other supporting equipment, playing techniques and game rules. This PkM is carried out on the basis of achievements for playing tonnis in Melawi Regency and there are very few seeds in the sport of playing tonnis because there are many obstacles in the formation of tennis players due to the lack of socialization and introduction to the community about tonnis. The benefit of this service is that STKIP Melawi students have a new reference for teaching small ball games in learning, besides that tennis can also be used in the educational curriculum at school.

On the design and the digital implementation of observer‐based controllers for tracking of nonlinear time‐delay systems

AbstractIn this article, the tracking control problem for a class of nonlinear time‐delay systems is investigated. In particular, a new methodology for the design and the digital implementation of observer‐based tracking controllers is provided for a class of control‐affine nonlinear systems with state delays. First, a procedure for the design of continuous‐time observer‐based tracking controllers ensuring the global asymptotic stability of the corresponding closed‐loop tracking error system is provided for the considered class of systems. Then, sufficient conditions are provided for the existence of a suitably fast sampling and of an accurate quantization of the input/output channels such that the digital implementation of the proposed continuous‐time observer‐based tracking controller ensures the semi‐global practical stability property of the related sampled‐data quantized closed‐loop tracking error system, with arbitrarily small final target ball of the origin. Moreover, it is shown that, in the special case of delay‐free nonlinear systems, the sufficient conditions provided for the digital implementation of the proposed continuous‐time observer‐based tracking controller can be strongly relaxed. In the theory here developed, time‐varying sampling periods and nonuniform quantization of the input/output channels are taken into account. The proposed results are validated through examples concerning a class of neural networks systems and a class of time‐delay systems including, as a special case, a delay‐free actuated inverted pendulum.

Pendampingan Pembuatan Label Dan Banner Sebagai Upaya Strategi Pemasaran Produk UMKM Cenil Mbok Mini

Cenil or Cetil is a traditional food or snack made from a mixture of starch and granulated sugar, colored, shaped into small balls, eaten with grated coconut. Cenil is a traditional Javanese snack, especially in the East Java area. Cenil mbok mini was founded in 1967 and is still active until now in 2023, so for around 56 years cenil mbok mini has become one of the culinary mainstays of Mojowiryo village, Kemlagi subdistrict, Mojokerto regency. Cenil is neatly packaged and increasingly modern in terms of packaging and manufacturing methods. This Community Service aims to introduce traditional food to the community, as well as to preserve traditional food so that it does not become extinct. The method used in this training is Preparation Step, Implementation Step, and Evaluation Step. As a result of this dedication, traditional snacks have labels to be marketed. Marketing strategies can help improve MSMEs.

CONVEXITY OF REACHABLE SETS OF QUASILINEAR SYSTEMS

This paper investigates convexity of reachable sets for quasilinear systems under integral quadratic constraints. Drawing inspiration from B.T. Polyak's work on small Hilbert ball image under nonlinear mappings, the study extends the analysis to scenarios where a small nonlinearity exists on the system's right-hand side. At zero value of a small parameter, the quasilinear system turns into a linear system and its reachable set is convex. The investigation reveals that to maintain convexity of reachable sets of these systems, the nonlinear mapping's derivative must be Lipschitz continuous. The proof methodology follows a Polyak's scheme. The paper's structure encompasses problem formulation, exploration of parameter linear mapping and image transformation, application to quasilinear control systems, and concludes with illustrative examples.

Media Development Based on Equipment Modifications in Table Tennis Games for Elementary Students

The purpose of this study was to introduce the game of small ball to elementary school students specifically in table tennis with a modification of the tool in the form of a table size that fits the body of elementary school children. This research method is development (Research and Development). The population of the research is sixth grade students at State Elementary Schools in Patumbak District, Deli Serdang Regency. The validation results of the expert questionnaire assessment were declared valid and usable with the percentage of media experts obtained at 83% in the valid category. Meanwhile, the percentage value from the meter expert was obtained at 80% in the valid category. Results of the questionnaire instrument assessment given to students during initial testingIt is known that the score obtained was 82% which was in the 80%-100% interval in the valid category. Results of the questionnaire instrument assessment given to students at the time large scale trialsIt is known that the score obtained was 83% which is in the 80%-100% valid category interval.So it can be said that teaching media products based on tool modification in table tennis games meet the criteria or are suitable for use by elementary school students as learning media. Conclusion, 1.The ideal size for mini table tennis has been created for class VI students at State Elementary Schools in Patumbak District. 2. Mini table tennis can be used by teachers and students in the physical education learning process in elementary schools.

ОСОБЛИВОСТІ ПОСТАНОВКИ ТЕОРЕТИЧНИХ НАВЧАЛЬНО-ДОСЛІДНИЦЬКИХ ЗАВДАНЬ З ФІЗИКИ

The article considers the necessity of introducing theoretical methods of idealization and mode ling in educational research. A brief overview of the problem of involving talented students in educational research not on a competitive basis, but for the organic development of their creative potential is given. The importance of theoretical educational research tasks in teaching physics is analyzed. A possible direction for organizing educational research aimed at developing the creative potential of talented students in physics and other natural-mathematical disciplines is proposed. Since curious students often put forward technically unrealizable ideas due to lack of factual knowledge and experience, the article provides an example of using a pedagogical technique known as “Socratic dialogue”. Examples of setting purely theoretical educational research tasks aimed at implementing methods for measuring the electric charge of a small ball suspended on a thread are given. Possible solutions to such problems are indicated for the case: 1) static equilibrium of such a ball in a horizontal electric field; 2) harmonic oscillations of a pendulum with a charged ball in a vertical electric field. A theoretical assess ment of the order of magnitude of results obtained from the practical creation of proposed measuring devices is carried out. The article’s conclusions provide an author’s vision of recommendations for implementing theoretical educational research in physics.

FRICTION STIR WELDING (FSW) APPLICATION TO JOINTS ALUMINUM FOR SEVERAL RADIUS

The FSW solid weld joint method can be used to joint several radius joints, which will be investigated for the strength of welded joints with 6061 aluminum material. with a size of 100 mm x 250 mm and a thickness of 5 mm, cut into a radius of 700mm, 900mm, 1000 mm, 1100mm, 1200 mm, and 1500 mm. The butt joint is joined by the friction stir welding (FSW) method using a milling machine. This experiment was carried out manually using universal milling with good results, it can be applied to modern machine buildings. The microstructure of the good results did not occur defects and manganese formed small balls in the FSW with a radius of 700 mm, the highest hardness test results occurred in the FSW with a radius of 1100 mm, namely 45 VHn, and the highest tensile strength occurred at a radius of 700 mm, which was 92 MPa.