Shape and diffusion instabilities of two non-spherical gas bubbles under ultrasonic conditions

Ultrasonic cavitation involves dynamic oscillation processes induced by small bubbles in a liquid under the influence of ultrasonic waves. This study focuses on the investigation of shape and diffusion instabilities of two bubbles formed during cavitation. The derived equations for two non-spherical gas bubbles, based on perturbation theory and the Bernoulli equation, enable the analysis of their shape instability. Numerical simulations, utilizing the modified Keller–Miksis equation,are performed to examine the shape and diffusion instabilities. Three types of shape instabilities, namely, Rayleigh–Taylor,Rebound, and parametric instabilities, are observed. The results highlight the influence of initial radius, distance, and perturbation parameter on the shape and diffusion instabilities, as evidenced by the R_0–P_a phase diagram and the variation pattern of the equilibrium curve. This research contributes to the understanding of multiple bubble instability characteristics, which has important theoretical implications for future research in the field. Specifically, it underscores the significance of initial bubble parameters, driving pressure, and relative gas concentration in determining the shape and diffusive equilibrium instabilities of non-spherical bubbles.

Flow Behaviors of Non-spherical Granules in Rectangular Hopper

Flow behaviors of four kinds of granular particles(i.e. sphere,ellipsoid,hexahedron and binary mixture of sphere and hexahedron) in rectangular hoppers were experimentally studied. The effects of granular shape and hopper structure on flow pattern,discharge fraction,mean particle residence time and tracer concentration distribu-tion were tested based on the visual observation and particle tracer technique. The results show that particle shape affects significantly the flow pattern. The flow patterns of sphere,ellipsoid and binary mixture are all parabolic shape,and the flow pattern shows no significant difference with the change of wedge angle. The flowing zone be-comes more sharp-angled with the increasing outlet size. The flow pattern of hexahedron is featured with straight lines. The discharge rates are in increasing order from hexahedron,sphere,binary mixture to ellipsoid. The dis-charge rate also increases with the wedge angle and outlet size. The mean particle residence time becomes shorter when the outlet size increases. The difference of mean particle residence time between the maximum and minimum values decreases as the wedge angle increases. The residence time of hexahedron is the shortest. The tracer concen-tration distribution of hexahedron at any height is more uniform than that of binary mixture. The tracer concentra-tion of sphere in the middle is lower than that near the wall,and the contrary tendency is found for ellipsoid particles.

Preparation of Non-spherical Colloidal Silica Nanoparticle and Its Application on Chemical Mechanical Polishing of Sapphire

Non-spherical colloidal silica nanoparticle was prepared by a simple new method, and its particle size distribution and shape morphology were characterized by dynamic light scattering(DLS) and the Focus Ion Beam(FIB) system. This kind of novel colloidal silica particles can be well used in chemical mechanical polishing(CMP) of sapphire wafer surface. And the polishing test proves that non-spherical colloidal silica slurry shows much higher material removal rate(MRR) with higher coefficient of friction(COF) when compared to traditional large spherical colloidal silica slurry with particle size 80 nm by DLS. Besides, sapphire wafer polished by non-spherical abrasive also has a good surface roughness of 0.460 6 nm. Therefore, non-spherical colloidal silica has shown great potential in the CMP field because of its higher MRR and better surface roughness.

Mechanism study of producing non-spherical powder in gas atomization

Gas atomization was usually regarded as a good method for producing the spherical or approximate spherical powders. We found a lot of non-spherical powders in production processes, especially in larger particle size distribution area. The causes of producing non-spherical powders are explained and some analyses are done in order to find a better condition of producing spherical powders in this paper. The following morphologies were obtained by atomized Fe50 Co50 and pure iron and investigated by scanning electron microscopy （SEM）.

Distribution of non-spherical nanoparticles in turbulent flow of ventilation chamber considering fluctuating particle number density

The Reynolds-averaged general dynamic equation(RAGDE)for the nanoparticle size distribution function is derived,including the contribution to particle coagulation resulting from the fluctuating concentration.The equation together with that of a turbulent gas flow is solved numerically in the turbulent flow of a ventilation chamber with a jet on the wall based on the proposed model relating the fluctuating coagulation to the gradient of mean concentration.Some results are compared with the experimental data.The results show that the proposed model relating the fluctuating coagulation to the gradient of mean concentration is reasonable,and it is necessary to consider the contribution to coagulation resulting from the fluctuating concentration in such a flow.The changes of the particle number concentration M_(0) and the geometric mean diameter dg are more obvious in the core area of the jet,but less obvious in other areas.With the increase in the initial particle number concentration m00,the values of M_(0) and the standard deviation of the particle sizeσdecrease,but the value of d_(g) increases.The decrease in the initial particle diameter leads to the reduction of M_(0) andσand the increase in d_(g).With the increase in the Reynolds number,particles have few chances of collision,and hence the coagulation rate is reduced,leading to the increase in M_(0) andσand the decrease in d_(g).

Simulation on hydrodynamics of non-spherical particulate system using a drag coefficient correlation based on artificial neural network

Fluidization of non-spherical particles is very common in petroleum engineering.Understanding the complex phenomenon of non-spherical particle flow is of great significance.In this paper,coupled with two-fluid model,the drag coefficient correlation based on artificial neural network was applied in the simulations of a bubbling fluidized bed filled with non-spherical particles.The simulation results were compared with the experimental data from the literature.Good agreement between the experimental data and the simulation results reveals that the modified drag model can accurately capture the interaction between the gas phase and solid phase.Then,several cases of different particles,including tetrahedron,cube,and sphere,together with the nylon beads used in the model validation,were employed in the simulations to study the effect of particle shape on the flow behaviors in the bubbling fluidized bed.Particle shape affects the hydrodynamics of non-spherical particles mainly on microscale.This work can be a basis and reference for the utilization of artificial neural network in the investigation of drag coefficient correlation in the dense gas-solid two-phase flow.Moreover,the proposed drag coefficient correlation provides one more option when investigating the hydrodynamics of non-spherical particles in the gas-solid fluidized bed.

Application of a Neural Network to Store and Compute the Optical Properties of Non-Spherical Particles

Radiative transfer simulations and remote sensing studies fundamentally require accurate and efficient computation of the optical properties of non-spherical particles.This paper proposes a deep learning(DL)scheme in conjunction with an optical property database to achieve this goal.Deep neural network(DNN)architectures were obtained from a dataset of the optical properties of super-spheroids with extensive shape parameters,size parameters,and refractive indices.The dataset was computed through the invariant imbedding T-matrix method.Four separate DNN architectures were created to compute the extinction efficiency factor,single-scattering albedo,asymmetry factor,and phase matrix.The criterion for designing these neural networks was the achievement of the highest prediction accuracy with minimal DNN parameters.The numerical results demonstrate that the determination coefficients are greater than 0.999 between the prediction values from the neural networks and the truth values from the database,which indicates that the DNN can reproduce the optical properties in the dataset with high accuracy.In addition,the DNN model can robustly predict the optical properties of particles with high accuracy for shape parameters or refractive indices that are unavailable in the database.Importantly,the ratio of the database size(~127 GB)to that of the DNN parameters(~20 MB)is approximately 6810,implying that the DNN model can be treated as a highly compressed database that can be used as an alternative to the original database for real-time computing of the optical properties of non-spherical particles in radiative transfer and atmospheric models.

NUMERICAL SIMULATIONS OF POLARIZED SCATTERING FROM RANDOM CLUSTERS OF SPATIALLY-ORENTED, NON-SPHERICAL SCATTERS

Employing multiple scattering formulation of T-matrix method, numerical simulations are developed and applied to polarized scattering from random clusters of spatially-oriented, non-spherical particles. Polarized scattering is numerically presented for the functional dependence on particle shape, size, spatial distribution and orientation, and other physical parameters. Numerical calculations of backscattering from randomly clustered particles are well compared with that from independent particles and clusters. It can be seen that spatial distribution and orientation of non-spherical particles can have significant effect on scattering.

Non-spherical particle mixing behaviors by spherical inert particles assisted in a fluidized bed

Fluidized beds are widely used in many industrial fields such as petroleum,chemical and energy.In actual industrial processes,spherical inert particles are typically added to the fluidized bed to promote fluidization of non-spherical particles.Understanding mixing behaviors of binary mixtures in a fluidized bed has specific significance for the design and optimization of related industrial processes.In this study,the computational fluid dynamic-discrete element method with the consideration of rolling friction was applied to evaluate the mixing behaviors of binary mixtures comprising spherocylindrical particles and spherical particles in a fluidized bed.The simulation results indicate that the differences between rotational particle velocities were higher than those of translational particle velocities for spherical and non-spherical particles when well mixed.Moreover,as the volume fraction of the spherocylindrical particles increases,translational and rotational granular temperatures gradually increase.In addition,the addition of the spherical particles makes the spherocylindrical particles preferably distributed in a vertical orientation.

A CFD-DEM-Wear Coupling Method for Stone Chip Resistance of Automotive Coatings with a Rigid Connection ParticleMethod for Non-Spherical Particles

The stone chip resistance performance of automotive coatings has attracted increasing attention in academic and industrial communities.Even though traditional gravelometer tests can be used to evaluate stone chip resistance of automotive coatings,such experiment-based methods suffer from poor repeatability and high cost.The main purpose of this work is to develop a CFD-DEM-wear coupling method to accurately and efficiently simulate stone chipbehaviorof automotive coatings inagravelometer test.Toachieve this end,an approach coupling an unresolved computational fluid dynamics(CFD)method and a discrete element method(DEM)are employed to account for interactions between fluids and large particles.In order to accurately describe large particles,a rigid connection particle method is proposed.In doing so,each actual non-spherical particle can be approximately described by rigidly connecting a group of non-overlapping spheres,and particle-fluid interactions are simulated based on each component sphere.An erosion wear model is used to calculate the impact damage of coatings based on particlecoating interactions.Single spherical particle tests are performed to demonstrate the feasibility of the proposed rigid connection particle method under various air pressure conditions.Then,the developed CFD-DEM-wear model is applied to reproduce the stone chip behavior of two standard tests,i.e.,DIN 55996-1 and SAE-J400-2002 tests.Numerical results are found to be in good agreement with experimental data,which demonstrates the capacity of our developed method in stone chip resistance evaluation.Finally,parametric studies are conducted to numerically investigate the influences of initial velocity and test panel orientation on impact damage of automotive coatings.

Epidemiology of work-related hand and wrist injuries in a referral center: A descriptive study

BACKGROUND Occupational hand and wrist injuries(OHWIs)account for 25%of work-related accidents in low-and middle-income countries.In Colombia,more than 500000 occupational accidents occurred in 2021,and although the rate declined to less than 5%in 2020 and 2021,at least one in four accidents involved a hand or wrist injury.AIM To describe the OHWIs in workers seen at the emergency room at a second-level hospital in Colombia.METHODS An observational study was performed using data from workers who experienced OHWIs and attended a second-level hospital,between June,2020 and May,2021.The overall frequency of OHWIs,as well as their distribution by sociodemo-graphic,clinical,and occupational variables,are described.Furthermore,association patterns between sex,anatomical area(fingers,hand,wrist),and type of job were analyzed by correspondence analysis(CA).RESULTS There were 2.101 workers treated for occupational accidents,423(20.3%)were cases of OHWIs,which mainly affected men(93.9%)with a median age of 31 years and who worked mainly in mining(75.9%).OHWIs were more common in the right upper extremity(55.3%)and comprised different types of injuries,such as contusion(42.1%),laceration(27.9%),fracture(18.7%),and crush injury(15.6%).They primarily affected the phalanges(95.2%),especially those of the first finger(25.7%).The CAs showed associations between the injured anatomical area and the worker’s job that differed in men and women(explained variance>90%).CONCLUSION One out of five workers who suffered occupational accidents in Cundinamarca,Columbia had an OHWI,affecting mainly males employed in mining.This occupational profile is likely to lead to prolonged rehabilitation,and permanent functional limitations.Our results might be useful for adjusting preventive measures in cluster risk groups.

Clinical and laboratory features of juvenile idiopathic arthritis with wrist involvement:Results of a retrospective cohort study

BACKGROUND Previous studies in the pre-biological era showed an association of wrist inflammation in juvenile idiopathic arthritis(JIA)with progressive disease course,polyarticular involvement and failure of methotrexate treatment.AIM To describe features of JIA,associated with wrist arthritis.METHODS Data from about 753 JIA patients were included in this retrospective cohort study.The clinical and laboratory features of patients with and without wrist involvement were analyzed.RESULTS Wrist involvement was found in oligoarthritis(5.8%),RF(−)/RF(+)polyarthritis(44.9%/15.0%),enthesitis-related arthritis(17.7%),and systemic(58.6%)JIA categories.Unilateral wrist involvement was typical for oligoarthritis patients,bilateral involvement was either equal to that of unilateral involvement or was more frequent in other categories.Wrist arthritis was found to be associated with female sex,a low incidence of uveitis,and more indications of systemic inflammation,including elevated levels of C-reactive protein,erythrocyte sedimentation rate,and platelets,as well as involvement of the cervical spine,temporomandibular,shoulder,elbow,metacarpophalangeal,proximal interphalangeal,distal interphalangeal,hip,ankle,and tarsus arthritis.The number of patients with hip osteoarthritis and hip replacement was also higher.Wrist arthritis was associated with a lower probability of achieving remission[hazard ratio(HR)=1.3(95%CI:1.0-1.7),P=0.055],and a higher probability of being treated with biologics[HR=1.7(95%CI:1.3-2.10,P=0.00009)].CONCLUSION Wrist arthritis in JIA patients is a marker of a severe disease course,characterized by more intensive inflammation,unfavorable outcomes,and.requiring more intensive treatment with early administration of biologics.Close monitoring of wrist inflammation with ultrasound and MR assessment with early biological treatment might improve the outcomes.

腕关节镜辅助Wristore外固定架治疗Barton骨折患者的效果

目的探讨腕关节镜辅助Wristore外固定架治疗Barton骨折患者的效果。方法选取2019年12月至2022年12月聊城市第三人民医院收治的100例Barton骨折患者进行随机对照试验,采用随机数字表法将其分为对照组和观察组,各50例。对照组男26例,女24例,年龄(40.26±3.58)岁;观察组男22例,女28例,年龄(43.55±2.44)岁。对照组采用常规治疗方法,观察组在常规治疗基础上采用腕关节镜辅助Wristore外固定架进行治疗。比较两组Gartland-Werley腕关节功能评分、疼痛视觉模拟量表(Visual Analogue Scale,VAS)评分、关节活动度及并发症发生率。统计学方法采用t检验、χ^(2)检验。结果治疗后,观察组Gartland-Werley腕关节功能评分(5.29±0.61)分,显著低于对照组的(12.42±2.90)分,差异有统计学意义(t=17.013,P<0.05)。观察组术后1周、1个月VAS评分均低于对照组[(3.24±1.16)分比(6.88±1.33)分、(1.45±0.94)分比(4.63±1.11)分],差异均有统计学意义(t=14.585、15.459,均P<0.05)。观察组关节活动度优于对照组[82%(41/50)比42%(21/50)],差异有统计学意义(χ^(2)=16.978,P<0.05)。观察组并发症发生率低于对照组[12%(6/50)比48%(24/50)],差异有统计学意义(χ^(2)=15.429,P<0.05)。结论腕关节镜辅助Wristore外固定架治疗Barton骨折患者效果良好,可以显著改善患者腕关节功能,降低疼痛程度,提高关节活动度,减少并发症的发生,值得在临床上广泛应用。

The Development of Dynamic Compliant Wrist for Robots

Based on an analysis of the relative shaft-to-hole position and attiude errors, as well as of the mechanics and Kinematics in the process of automatic assembly of industrial robots, the paper studies the principle of construction of dynamic wrists. Type I-3 and Ⅱ-6 dynamic compliant wrists have been designed and made. Prblems in the production of compliant elements and the connection between compliant elements and wrists were also solved. A study on the results of tests of the function of two kinds of dynamic compliant wrists shows that the dynamic compliant wrist's compliancy function can be improved by adding metallic materials having higher longitudinal and transverse rigidity into the softer elstomer. And the design Principle is proved to be feasible and practicable. It can be expected that the use of dynamic compliant wrist will greatly lower the technical requirements of the shaft-hole assembly and the requirements in the resetting accuracy.

Arthrodesis of the wrist in rheumatoid arthritis

In rheumatoid arthritis the small joints of the feet and hands are the first targets of the autoimmune process. In about one half of the patient the wrist is involved in the first stages of the disease(two years) increasing up to nearly 90 percent after a decade often including both sides. Osteoarthritis of the wrist is one of the most common conditions encountered by hand surgeons. One aim of all treatment options is to achieve the best possible hand function without pain. If conservative treatment fails, operative treatment is necessary. Choice of surgical treatment depends on the soft tissue and bone situation. Techniques can be differentiated by joint preservation or joint replacement. The first include radio-synoviorthesis, synovectomy and tendon repair, the latter resection-arthroplasty, total joint arthroplasty and arthrodesis. In this paper arthrodesis of the wrist as one treatment option is reviewed.

Free Flow-through Anterolateral Thigh Flaps for Wrist High-tension Electrical Burns:A Retrospective Case Series

Objective The objective of this report was to demonstrate the clinical application of free flow-through anterolateral thigh flaps for the treatment of high-tension electrical wrist burns.Methods We collected the data of 8 patients with high-tension electrical wrist burns admitted to Beijing Jishuitan Hospital from January 2014 to December 2018.The clinical and pathological data were extracted from electronic hospital medical records.We obtained follow-up information through clinic visits.Results The injury sites for all 8 patients were the wrists,specifically 5 right and 3 left wrists,all of which were on the flexor side.Five patients had ulnar artery embolism necrosis and patency,with injury to the radial artery.Two patients had ulnar and radial arterial embolization and necrosis.The last patient had ulnar arterial embolization and necrosis with a normal radial artery.After debridement,the wound area ranged from 12 cm×9 cm to 25 cm×16 cm.The diagnoses for the eight patients were type II to type III high-tension electrical wrist burns.Free flow-through anterolateral thigh flaps(combined with great saphenous vein transplantation if necessary)were used to repair the wounds.The prognosis for all patients was good after six months to one year of follow-up.Conclusion Treating wrist types II and III high-tension electrical burns is still challenging in clinical practice.The use of free flow-through anterolateral thigh flaps(combined with great saphenous vein transplantation if necessary)to repair the wound and to restore the blood supply for the hand at the same time is a good choice for treating severe wrist electrical burns.

Wrist circumference: A new marker for insulin resistance in African women with polycystic ovary syndrome

BACKGROUND Insulin resistance(IR)is the main complication found in 35%-80%of women with polycystic ovary syndrome(PCOS).However,there is no definite consensus regarding which marker to use for its assessment in PCOS women.Research has shown that hyperinsulinemia is correlated with increased bone mass.Given that most women with PCOS are insulin resistant,which is independent from body fat and characterized by hyperinsulinemia,it could be hypothesized that there would be an increased bone mass in the patient as a result.Subsequently,increased bone mass could be measured using the wrist circumference method.AIM To assess the wrist circumference as an easy-to-detect marker of IR in Congolese women with PCOS.METHODS Seventy-two Congolese women with PCOS and seventy-one controls from the same ethnic group,were enrolled in the study(mean age 24.33±5.36 years).Fasting biochemical parameters,and the Homeostasis Model Assessment of insulin resistance(HOMA-IR)and body composition were evaluated.The nondominant wrist circumference was measured manually,as was the waist circumference(WC),hip circumference,height and weight.Calculated measures included evaluation of body mass index(BMI),Waist-to-Height(WHtR)and Waist-to-hip ratio(WHR).In addition,body composition was assessed by Bioelectrical Impedance Analysis using a body fat analyzer.RESULTS The non-dominant wrist circumference was more closely correlated with HOMAIR(r=0.346;P=0.003)and was the best anthropometrical marker correlated with IR(P=0.011)compared with other anthropometrical markers in women with PCOS:Dominant Wrist Circumference(r=0.315;P=0.007),Waist Circumference(WC)(r=0.259;P=0.028),BMI(r=0.285;P=0.016),WHR(r=0.216;P=0,068)and WHtR(r=0.263;P=0.027).The diagnostic accuracy of the non-dominant wrist circumference for the presence or absence of IR using Receiver-operating characteristic(ROC)curve analysis showed that the area under the ROC curve was 0.72.A cutoff value for the non-dominant wrist circumference of 16.3 cm was found to be the best predictor of IR in Congolese women with PCOS.CONCLUSION Non-dominant wrist circumference is,to date,the best anthropometrical marker of IR in Sub-Saharan African women with PCOS.It could be suggested as an easy-to-detect marker for assessing IR.

Idiopathic tenosynovitis of the wrist with multiple rice bodies: A case report and review of literature

BACKGROUND Multiple rice bodies in the wrist is a rare disorder that requires surgery,and there are still many uncertainties regarding its diagnosis and treatment.CASE SUMMARY We described a rare case of chronic idiopathic tenosynovitis with rice bodies of the wrist in a 71-year-old man and reviewed similar topics in the literature.A total of 43 articles and 61 cases were included in the literature review.Our case had a usual presentation:it was similar to those in the literature.The affected population was mainly older adults,with an average age of 59.43(range,3 to 90)years.The male-to-female ratio was 1.54:1(37/24).Most of them showed limited swelling and pain,only 23.0%had carpal tunnel symptoms,and the average disease duration was 18.03(0.5-60)mo.Wrist flexor tendon sheath involvement was the most common(95.1%,58/61),and only 3 cases had extensor tendon sheath involvement.The main causes were tuberculosis(34.4%,21/61),nontuberculous mycobacteria(24.6%,15/61),idiopathic tenosynovitis(31.1%,19/61),and others(9.84%,6/61).There were 10 patients with recurrences;in 6 of them,were due to non-tuberculous mycobacterial infections.CONCLUSION We reported a case of wrist idiopathic tenosynovitis with rice body formation,and established a clinical management algorithm for wrist tenosynovitis with rice bodies,which can provide some reference for our clinical diagnosis and treatment.The symptoms of rice-body bursitis of the wrist are insidious,nonspecific,and difficult to identify.The aetiology is mainly idiopathic tenosynovitis and mycobacterial(tuberculosis or non-tuberculous)infections;the latter are difficult to treat and require long-duration systemic combination antibiotic therapies.Therefore,before a diagnosis of idiopathic tenosynovitis is made,we must exclude other causes,especially mycobacterial infections.

Deep Learning Based Classification of Wrist Cracks from X-ray Imaging

Wrist cracks are the most common sort of cracks with an excessive occurrence rate.For the routine detection of wrist cracks,conventional radiography(X-ray medical imaging)is used but periodically issues are presented by crack depiction.Wrist cracks often appear in the human arbitrary bone due to accidental injuries such as slipping.Indeed,many hospitals lack experienced clinicians to diagnose wrist cracks.Therefore,an automated system is required to reduce the burden on clinicians and identify cracks.In this study,we have designed a novel residual network-based convolutional neural network(CNN)for the crack detection of the wrist.For the classification of wrist cracks medical imaging,the diagnostics accuracy of the RN-21CNN model is compared with four well-known transfer learning(TL)models such as Inception V3,Vgg16,ResNet-50,and Vgg19,to assist the medical imaging technologist in identifying the cracks that occur due to wrist fractures.The RN-21CNN model achieved an accuracy of 0.97 which is much better than its competitor`s approaches.The results reveal that implementing a correct generalization that a computer-aided recognition system precisely designed for the assistance of clinician would limit the number of incorrect diagnoses and also saves a lot of time.

WRIST FORCE SENSOR'S DYNAMIC PERFORMANCE CALIBRATION BASED ON NEGATIVE STEP RESPONSE

Negative step response experimental method is used in wrist force sensor＇s dynamic performance calibration. The exciting manner of negative step response method is the same as wrist force sensor＇s load in working. This experimental method needn＇t special experiment equipments. Experiment＇s dynamic repeatability is good. So wrist force sensor＇s dynamic performance is suitable to be calibrated by negative step response method. A new correlation wavelet transfer method is studied. By wavelet transfer method, the signal is decomposed into two dimensional spaces of time-frequency. So the problem of negative step exciting energy concentrating in the low frequency band is solved. Correlation wavelet transfer doesn＇t require that wavelet primary function be orthogonal and needn＇t wavelet reconstruction. So analyzing efficiency is high. An experimental bench is designed and manufactured to load the wrist force sensor orthogonal excitation force/moment. A piezoelectric force sensor is used to setup soft trigger and calculate the value of negative step excitation. A wrist force sensor is calibrated. The pulse response function is calculated after negative step excitation and step response have been transformed to positive step excitation and step response. The pulse response function is transferred to frequency response function. The wrist force sensor＇s dynamic characteristics are identified by the frequency response function.