Ball Size Research Articles

Performance Improving of a Concentrating Photovoltaic System by Using a New Optical Adhesive

The objective of this present study is to manufacture a new silicone-based adhesive which is used for gluing and bonding the second optical elements (SOE) with Concentrating Photovoltaic solar cell (CPV) in order to guarantee a thickness that can provide a good silicone adherence to obtain long term stability and keeping a good solar transmittance performance, too. This new adhesive is made up of a mixture of silicone and transparent glass balls. The experimental part consists of the choice of the best size of glass balls with the suitable proportion of the glass balls weight in the mixture. For this purpose, ten samples were manufactured for every category of glass balls and weight ratio. Glass ball sizes between 100 and 1100 μm, and weight ratios between 1 and 10% were analyzed. For each category of glass balls, four proportions were mixed with the silicone. The thicknesses and transmittance of every sample were measured with appropriate instruments. The experimental results illustrate that the mixture containing balls with sizes inferior to 106 μm, is the best mixture which assures adhesive minimum thickness value necessary for an efficient mechanical bond and preserves also a good transmittance of solar irradiance.

Quantifying the destructuring of a thixotropic colloidal suspension using falling ball viscometry

The settling dynamics of falling spheres inside a Laponite suspension is studied. Laponite is a colloidal synthetic clay that shows physical aging in aqueous suspensions due to the spontaneous evolution of inter-particle electrostatic interactions. In our experiments, millimeter-sized steel balls are dropped in aqueous Laponite suspensions of different ages (i.e., time elapsed since sample preparation). The motion of the falling balls is captured using a high-speed camera, and the velocities of their centroids are estimated from the images. Interestingly, we observe that balls of larger diameters fail to achieve terminal velocity over the entire duration of the experiment. We propose a mathematical model that accounts for rapid structural changes (expected to be induced by the falling ball) in Laponite suspensions whose aging time scales are much slower than the time of fall of the ball. For a range of ball sizes and Laponite suspension ages, our model correctly predicts the time dependence of the ball velocity. Furthermore, fits to our model allow us to estimate the rates of destructuring of the thixotropic suspensions due to the passage of the falling ball.

Research on ball milling process of Mn powder for ceramic metal welding

The main content of this experiment is to study the optimal ball milling process of Mn powder by controlling the factors such as ball milling ratio, ball milling time and grinding ball size. In the experiment, the Mn powder was ground by wet ball milling method. Ethanol was used as the medium to set different powder: ball: ethanol ratio. The microstructures of Mn were studied by grinding for 6 h, 18 h and 24 h at 400 r/min. The XRD, Scanning Electron Microscope and particle size analyzer were used to analyze the phase, microstructure and particle size of the powder. The results show that the ratio of the crushing rate of material to the time of ball milling are not related. In the initial stage of ball milling, Mn powder was rapidly crushed and refined, but the particle size gradually stabilized after 18 hours. The grinding ball with smaller diameter is slower to crush, but the particle size of Mn powder is more uniform. When the quality of powder: ball: ethanol =1:1.5:1.5, the obtained Mn powder has the finest particle size and uniform particles, which is the best grinding condition. After ball milling, the average particle size of Mn powder is 2.04 μm.

RETRACTED: Optimization of volleyball motion estimation algorithm based on machine vision and wearable devices

Volleyball is a team sport of track video-based analysis essential. However, this is difficult, especially in machine vision and wearable devices. Due to the ball's small size, its speed of motion blur is generated, generally blocked. Older systems find it difficult to analyze the level of volleyball. When tracking with machine vision and wearable devices, it is recommended that Volleyball Motion Estimation Algorithms improve robustness to player confusion between different particle series. Faster processing speed and less confusing players presented herein as a method superior to the conventional particulate filter. The ball and Volleyball Motion Estimation Algorithm uses machine vision and wearable devices to detect differential picture, and motion machine vision wearable device is optimized. Optimized toss Volleyball is correct by the Volleyball Motion Estimation Algorithm, and the trajectory is almost equal to the false prediction of the ball's size. Machine vision and wearable devices can provide a new sports attendance watching experience through predictive images superimposed on live broadcasts. This also shows that the method can identify some important parts of the body to help predict thrown. Compared to the previous system, which provides better results.

The Effect of Using Different Ball Weights and Sizes on Developing Some Fundamental Skills in Soccer

The research aimed at identifying the effect of using exercises with different ball sizes and weights on developing some fundamental skills in soccer players aged 9 – 10 years old. The researchers used the experimental method on (20) soccer players from Amo Baba Soccer School. The subjects were equally divided into two groups. The results showed that using different ball weights and sizes have positive effects on fundamental skill development and significantly improving the level of performance in the experimental group that used ball with lesser weights and smaller size compared to the controlling group. The researchers recommended that coaches and supervisors should use balls of different weights and sizes when teaching soccer to younger age groups U10.

Multidisciplinary Management of a Rare Case of a Huge LowGrade Chondrosarcoma of the Lumbar Spine: A Case Report

Introduction: Chondrosarcoma is the second most common primary bone sarcoma and arising in the spine. It is estimated to be 2% to 12% in incidence from various series. The use of neoadjuvant and adjuvant chemotherapy for chondrosarcomas is controversial. Low- and intermediate-grade chondrosarcomas respond poorly to chemotherapy. Although not much data on the efficacy of chemotherapy in the treatment of high-grade chondrosarcomas, it should be considered in any young patient with a high-grade tumor. Radiation is recommended when anything other than wide excision is performed for chondrosarcoma of any grade.Case Presentation: A 24-year old female presented to the clinic with a chief complaint of persistent low back pain and a lump in her back. Initially, the lump was the size of a tennis ball three years ago. At the time of the examination, the lump was at the size of a volleyball about 65 x 63 x 58 centimeters. Systemic and general examinations were unremarkable. There were no comorbid conditions. From the results of the Clinicopathological Conference conducted by neurologists, pathologists, radiologists, orthopedic spine and oncology surgeons, it is advisable to conduct investigations such as x-rays, CT scans, MRI, biopsy, and surgery is recommended for evaluation of expansion of chondrosarcoma, evolving the spinal cord, and for resection of tumors.Conclusion: Early diagnosis and complete resection of tumor and treatment of relevant symptoms represent a viable treatment for this rare disorder to achieve increased life expectancy, low recurrence of tumor, and improvement of quality of life.

Ultrafine dry grinding of talc by planetary mill: effects of operating conditions

Ultrafine grinding is required in most industrial applications of talc. In this work, a planetary mill was used to produce a d50 product of less than 5 μm. The effects of grinding time, media size, mill filling, rotational speed, and media-to-powder ratio, as the main grinding parameters, were initially investigated by the one-variable-at-a-time strategy. In addition, the statistical design method was applied to optimize and correlate the d90 and d50 of the ground product to the media-to-talc percentage and grinding time, being the most significant variables for talc grinding in a planetary mill. The results indicate that the ball size significantly affects the product fineness up to a certain ball size (i. e., 4 mm), after which the product becomes coarser. At the same time, lower mill filling and higher mill rpm yield finer products. The agglomeration of particles under dry conditions is the main constraint to size reduction below certain limits. The maximum size reduction obtained in grinding with the 85 % media-to-powder ratio, 30 % mill filling, and higher rotational speed (300 rpm) during 30 min grinding cycles was 14.6 μm and 4.5 μm for d90 and d50 of the ground product, respectively.

Kinetics of Dry-Batch Grinding in a Laboratory-Scale Ball Mill of Sn–Ta–Nb Minerals from the Penouta Mine (Spain)

The optimization of processing plants is one of the main concerns in the mining industry, since the comminution stage, a fundamental operation, accounts for up to 70% of total energy consumption. The aim of this study was to determine the effects that ball size and mill speed exert on the milling kinetics over a wide range of particle sizes. This was done through dry milling and batch grinding tests performed on two samples from the Penouta Sn–Ta–Nb mine (Galicia, Spain), and following Austin methodology. In addition, the relationships amongst Sn, Ta and Nb content, as metals of interest, the specific rate of breakage Si, the kinetic parameters, and the operational conditions were studied through X-Ray fluorescence (XRF) techniques. The results show that, overall, the specific rate of breakage Si decreases with decreasing feed particle size and increasing ball size for most of the tested conditions. A selection function, αT, was formulated on the basis of the ball size for both Penouta mine samples. Finally, it was found that there does exist a direct relationship amongst Sn, Ta and Nb content, as metals of interest, in the milling product, the specific rate of breakage Si and the operational–mineralogical variables of ball size, mill speed and feed particle size.

Application of discrete element simulation in mechanical activation of boron concentrate

We have studied the change of the specific surface area of the ground powder and the dynamics of balls and powders with several milling parameters such as the ball to powder ratio, the size of balls, the filling ratio, and the rotational speed of the vial in the mechanical activation process of boron concentrate by high-energy planetary ball mill. The results have shown that the ball movement regime for good grinding efficiency of the planetary ball mill is “cascading” or light “cataracting”, and contact forces have a greater effect on the grinding of powders than collision forces. The grinding efficiency is related to the compressive force, the contact force, the kinetic energy of the balls, and the number of contacts, however, the compressive force and contact force seem to have a significant effect. The greater the compression and contact forces, the greater the grinding efficiency of powders.

Exploring the End-Liner Forces Using DEM Software

The main roles of liners are to protect the mill shell and promote effective ball motion for grinding. For this reason the liner profile is carefully selected to ensure that the productivity is maximized and due liner replacement is made when this objective is no longer met. These issues have been extensively studied on shell liners as mill relining is a significant cost component of ball milling. To date, not much has been written about end-liners and the kind of forces they are subjected to. A discrete element method (DEM) simulation scheme is conducted to look at how ball size distribution, mill filling, end-liner configuration and shape affect the distribution of forces acting on the liners that were assessed to understand end-liner wear and damage. The results showed how forces varied both radially and tangentially for the different sections of end-liner, with important insights drawn for end-liner manufactures.

Data-Driven Optimization of Reward-Risk Ratio Measures

We investigate a class of fractional distributionally robust optimization problems with uncertain probabilities. They consist in the maximization of ambiguous fractional functions representing reward-risk ratios and have a semi-infinite programming epigraphic formulation. We derive a new fully parameterized closed-form to compute a new bound on the size of the Wasserstein ambiguity ball. We design a data-driven reformulation and solution framework. The reformulation phase involves the derivation of the support function of the ambiguity set and the concave conjugate of the ratio function. We design modular bisection algorithms which enjoy the finite convergence property. This class of problems has wide applicability in finance, and we specify new ambiguous portfolio optimization models for the Sharpe and Omega ratios. The computational study shows the applicability and scalability of the framework to solve quickly large, industry-relevant-size problems, which cannot be solved in one day with state-of-the-art mixed-integer nonlinear programming (MINLP) solvers.

Evaluation of Temperature Distribution Around the Probe in Cryoablation of Lipiodol-Mixed-Tissue Phantom.

To determine whether lipiodol, which has low thermal conductivity, influences ice ball formation during cryoablation of a lipiodol-mixed-tissue phantom. Lipiodol-mixed-tissue phantoms were created by injecting lipiodol (4-6ml) into the renal arteries of ex vivo porcine kidneys (lipiodol group). A cryoprobe (CryoHit™ Needle S) with a holder that was set with thermocouples at various positions around the cryoprobe was inserted. After freezing for 300s, the followings were evaluated: ice ball size on CT, temperature distribution around the cryoprobe, and calculated distances at 0°C and -20°C. Each variable was compared between lipiodol group (n = 6) those obtained in a control group without lipiodol injection (n = 6). Mean ice ball diameter (width/length) on CT was 22.1 ± 2.3/22.9 ± 2.3mm in the lipiodol group and 21.6 ± 0.7/22.2 ± 1.3mm in the control group. Mean cryoprobe temperature was -118 ± 3.0°C in the lipiodol group and -117 ± 2.6°C in the control group. In both groups, temperature at the 3mm thermocouple reached approximately -50°C and was < 0°C within ~ 10mm of the cryoprobe. Temperature of 0/-20°C occurred at a mean distance from the cryoprobe of 11.1 ± 0.5/6.9 ± 0.4mm in the lipiodol group and 11.0 ± 0.2/6.9 ± 0.2mm in the control group. There was no significant difference in any variable between the groups. The inclusion of lipiodol in a tissue phantom had no negative effects on ice ball formation that were related to thermal conductivity.

Application of an Inertia Dependent Flow Friction Model to Snow Avalanches: Exploration of the Model Using a Ping-Pong Ball Experiment

Snow avalanches are catastrophic phenomena because of their destructive power. Therefore, it is very important to forecast the affected area of snow avalanches using numerical simulations. In our study, we focus on applying a numerical model to snow avalanches. The inertia-dependent flow friction model, which we call the “I-dependent” model, is a promising numerical model based on granular flow experiments and includes the local inertial effect. This model was introduced in previous studies as it predicts the shape and velocity of the granular flow accurately. We numerically investigated the particle diameter effect of the I-dependent model, and found that the smaller the particle diameter is, the faster the flow front velocity becomes. The final flow shape is similar to a crescent shape when the particle diameter is small. We applied this model to the ping-pong ball flow experiment, which imitated a snow avalanche on a ski jump slope. Comparing between the experimental and simulated results, the flow shape is better reproduced when the particle diameter is small, while the numerical simulation using a real ping-pong ball diameter did not show the clear crescent shape. Moreover, the relative error analysis shows that the best fit between experimental and simulated flow front velocity occurs when the particle diameter is larger than the actual size of a ping-pong ball. We conjecture that this discrepancy is mainly caused by aerodynamic effects, which, in this case, are large due to the low density of ping-pong balls. Therefore, it is necessary to explore the granular features of ping-pong balls or snow avalanches by conducting experiments, as done in previous experimental studies. Through such efforts, it may be possible to apply this I-dependent model to snow avalanches in the future.

Differences in the reproductive behaviour and larval development of two Canthon rutilans subspecies reinforce their thermal regional segregation

AbstractTwo dung beetle subspecies of Canthon rutilans Castelnau (Coleoptera: Scarabaeidae, Scarabaeinae), C. rutilans rutilans and C. rutilans cyanescens, inhabit different environmental temperature conditions in southern Brazil. We developed a laboratory breeding experiment with 60 pairs of individuals of the two subspecies at five temperature conditions (from 15 to 35 °C) to compare the influence of temperature on the behaviour of adults and the development of larvae. The behavioural patterns of the adults in both subspecies differ according to temperature. The size of food balls was smaller and lighter in C. rutilans cyanescens. Although temperature did not influence the feeding behaviour (measured as the number of food balls made), reproductive behaviour (measured as the number of brood balls made by pair) was significantly lower at 15 °C for both subspecies. Besides that, brood balls from C. rutilans rutilans were bigger and heavier at lower temperatures. The number of offspring and the time of emergence depend on temperature too. However, the weight of the offspring and the longevity of adults depend on the subspecies and temperature treatment. These results demonstrate that the subspecies have different thermal adaptations: C. rutilans rutilans has reproductive behaviour adapted to living under colder and broader conditions than C. rutilans cyanescens.

Behavioural responses to warming differentially impact survival in introduced and native dung beetles.

Anthropogenic changes are often studied in isolation but may interact to affect biodiversity. For example, climate change could exacerbate the impacts of biological invasions if climate change differentially affects invasive and native species. Behavioural plasticity may mitigate some of the impacts of climate change, but species vary in their degree of behavioural plasticity. In particular, invasive species may have greater behavioural plasticity than native species since plasticity helps invasive species establish and spread in new environments. This plasticity could make invasives better able to cope with climate change. Here our goal was to examine whether reproductive behaviours and behavioural plasticity vary between an introduced and a native Onthophagus dung beetle species in response to warming temperatures and how differences in behaviour influence offspring survival. Using a repeated measures design, we exposed small colonies of introduced O. taurus and native O. hecate to three temperature treatments, including a control, low warming and high warming treatment, and then measured reproductive behaviours, including the number, size and burial depth of brood balls. We reared offspring in their brood balls in developmental temperatures that matched those of the brood ball burial depth to quantify survival. We found that the introduced O. taurus produced more brood balls and larger brood balls, and buried brood balls deeper than the native O. hecate in all treatments. However, the two species did not vary in the degree of behavioural plasticity in response to warming. Differences in reproductive behaviours did affect survival such that warming temperatures had a greater effect on survival of offspring of native O. hecate compared to introduced O. taurus. Overall, our results suggest that differences in behaviour between native and introduced species are one mechanism through which climate change may exacerbate negative impacts of biological invasions.

Pulmonary Hamartoma, A Relatively Common Diagnosis with a Rare Presentation

Abstract Casestudy: Pulmonary hamartomas (PH) are the most common benign tumors of lung, accounting for 75% of all the benign tumors and 8% of all the pulmonary neoplasms. These lung tumors are generally solitary and are observed in middle-aged and older adults with the peak incidence during the sixth decade of life. PH presents as asymptomatic nodule, found incidentally on routine radiographs and CT scans. The majority of PH are located in the lung parenchyma. Endobronchial hamartomas occur much less frequently. An extremely rare presentation of Hamartoma as a mediastinal mass is also reported in the past. The present article reports a case of a 72-year-old female, presented to her primary care physician with the complains of right lower abdominal pain. CT scan of the abdomen and pelvis revealed a partially visualized right paracardiac /mediastinal lipomatous mass. Patient stated that she was informed about a pericardial cyst of about golf ball size, noticed on a routine radiograph 40 years ago. Further workup with CT chest angiography revealed an 8.6 x 5.6 x 5.6 cm mediastinal mass associated with the right heart border and the right cardiophrenic angle, abutting the right diaphragm as well as the medial pleural reflection. A differential diagnosis of teratoma, lipoma/liposarcoma, and hamartoma was considered. Patient underwent robotic assisted surgical resection of the mass which emanated from right lower lung lobe. The histologic features and immunoreactivity pattern were consistent with a benign pulmonary hamartoma. Approximately 90 percent of PH presents as a peripheral intraparenchymal nodule whereas endobronchial hamartoma occurs much less frequently and represents 1.4% - 10 % of PH. A few cases of pulmonary hamartomas presenting as a mediastinal mass have been reported in the past few decades. Here in we report such a case of pulmonary hamartoma presenting as a mediastinal mass.

Factors affecting peak impact force during soccer headers and implications for the mitigation of head injuries.

It has been documented that up to 22% of all soccer injuries are concussions. This is in part due to players purposely using their head to direct the ball during play. To provide a more complete understanding of head trauma in soccer athletes, this study characterized the effects of four soccer ball characteristics (size, inflation pressure, mass, velocity) on the resulting peak impact force as it relates to the potential for incurring neurophysiological changes. A total of six hundred trials were performed on size 4 and 5 soccer balls as well as a novel lightweight soccer ball. Impact force was measured with a force plate and ball velocity was determined using motion capture. These data were used, in conjunction with dimensional analysis to relate impact force to ball size, mass, velocity, and pressure. Reasonable reductions in allowable ball parameters resulted in a 19.7% decrease in peak impact force. Adjustments to ball parameters could reduce a high cumulative peak translational acceleration soccer athlete down into a previously defined safer low loading range. In addition, it was noted that water absorption by soccer balls can result in masses that substantially increase impact force and quickly surpass the NCAA weight limit for game play. Additional research is required to determine whether varying soccer ball characteristics will enable soccer players to avoid persistent neurophysiological deficits or what additional interventions may be necessary and the legal implications of these data are discussed.

Effect of milling ball size on the densification and optical properties of transparent Y2O3 ceramics

In this study, we report highly transparent Y2O3 ceramics fabricated by hot-pressing only at 1500 °C without a HIP treatment, featuring in-line transmittance levels of 77% and 84% at a wavelength of 400 and 1100 nm, respectively with the grain size suppressed to 710 nm. The effect of the ball size during the grinding of Y2O3 powders on the correlation between the thus-prepared Y2O3 powders and the optical properties of the hot-pressed samples is demonstrated for the first time. With a decrease in the diameter of the ZrO2 balls from 5 mm to 1 mm, the milling efficiency was enhanced and admirable transparency of Y2O3 was attained at a short milling time. However, several micron-sized pores remained in the transparent specimens prepared with 1 mm balls, originating from the inhomogeneously packed region of the green body. Finally, the 2 mm was found to be optimum for obtaining a fine-grained and pore-free microstructure with the best in-line transmittance of Y2O3 ceramics.

An innovative approach for determining the grinding media system of ball mill based on grinding kinetics and linear superposition principle

Herein, an innovative approach for determining the grinding media system of ball mill based on grinding kinetics and linear superposition principle was proposed. The optimal media ball size of −2 + 0.45 mm, −0.45 + 0.15 mm, and − 0.15 mm feeding samples were 40 mm, 30 mm, and 30 mm, respectively. According to the linear superposition principle, the media size ratio is equal to the yield of ores. The optimal media proportion was φ 50 mm: φ 40 mm: φ 30 mm = 28%: 28%: 44% via wet grinding experiment, in which the yield of qualified granular material (−0.074 + 0.03 mm) suitable for beneficiation was the largest in the ground products. The optimized space-filling factor and material media ratio was 35% and 1.0 through the wet grinding experiment. According to the energy consumption method, the mathematical function models of installed power and mill productivity vs. space-filling factors were established to calculate the installed power and productivity of an industrial ball mill (Φ5.03 m × 6.40 m).

Microstructural and Passivation Response of Severely Deformed AISI 304 Steel Surface: The Role of Surface Mechanical Attrition Treatment

The present study investigates the microstructural and passivation behavior of surface mechanical attrition treated (SMAT) AISI 304 stainless steel in a 0.6 M NaCl solution at room temperature. SMAT process, which is more advanced than the classical shot-peening, causes 2-3 times improvement in surface hardness of the steel. Ball size, a vital SMAT parameter, plays a significant role in controlling the microstructure and corrosion behavior of the steel. Larger diameter (6 mm) balls induce thicker deformed layer (450 μm), a higher proportion of deformation-induced martensite (~ 50%), a higher density of dislocations and twins, and higher lattice strain. TEM results confirm the presence of {111} twins throughout the deformed layer. SMAT enhances the corrosion properties of the steel. Specimen SMATed with 4-mm-diameter-balls displays the lowest corrosion rate (1.80 × 10−4 mmpy). SMAT increases the pitting resistance of the steel surface. XPS is utilized to understand the passivation mechanism of steel comprehensively. SMAT alters the proportion of Cr2O3, Cr(OH)3, Fe2O3, and FeO compounds in the passive layer. SMAT increases the thickness of the passive layer.