Wear Mechanisms of the Working Surface of Gears after Scuffing Tests.

Identification of changes occurring on the working surface of lubricated gears using analytical equipment, e.g., an FE-SEM scanning electron microscope with an EDS microanalyzer, a WLI interferometric microscope, or a GDEOS optical discharge spectrometer, enables the characterisation of wear mechanisms of this surface. Definition of the phenomena occurring on the surface of tribo-couples after scuffing tests enables a comparative analysis of scuffing resistance and surface properties of the micro- and nanostructure, and elemental composition of the tested gears. Recognition and analysis of the wear mechanisms occurring on the working surface of gears will reduce the risk of damage and losses resulting from the need for maintenance and repair. The study concerned the working surfaces of gears made of 17HNM and 35HGSA steels on which a W-DLC/CrN coating was deposited. Shell Omala S4 GX 320 commercial industrial oil with a synthetic PAO (polyalphaolefin) base was selected for the lubrication of the gears. Tribological tests employed an FZG gear scuffing under severe conditions test method and they were carried out on a T-12U test rig for cylindrical gear analysis.

Abrasive Wear Resistance of Ultrafine Ausferritic Ductile Iron Intended for the Manufacture of Gears for Mining Machinery.

The purpose of this study was to experimentally determine the abrasion wear properties of ausferritic ductile iron austempered at 250 °C in order to obtain cast iron of class EN-GJS-1400-1. It has been found that such a cast iron grade makes it possible to create structures for material conveyors used for short-distance transport purposes, required to perform in terms of abrasion resistance under extreme conditions. The wear tests addressed in the paper were conducted at a ring-on-ring type of test rig. The test samples were examined under the conditions of slide mating, where the main destructive process was surface microcutting via loose corundum grains. The mass loss of the examined samples was measured as a parameter characteristic of the wear. The volume loss values thus obtained were plotted as a function of initial hardness. Based on these results, it has been found that prolonged heat treatment (of more than 6 h) causes only an insignificant increase in the resistance to abrasive wear.

Study of the Impact of Coals and Claystones on Wear-Resistant Steels.

This paper discusses the impact of coal abrasive materials of varied petrographic composition and claystones containing admixtures of coal matter on the surface wear of wear-resistant martensitic steels. Wear tests were conducted at a test stand for three petrographic varieties of hard coal: vitrinite, clarinite, and durinite, and five samples of claystone. These tests revealed no significant effect of the type of coal abrasive used on the value of mass loss from the surface of the wear-resistant steel samples. The reason behind the foregoing is the observed tendency of coal abrasives, irrespective of their petrographic variety, to penetrate surface irregularities, especially those attributable to previous surface treatment of the samples and the impact of wear products. The dominant forms of surface damage were surface fatigue chipping and scratches caused by the particles which detached themselves from the surface of the steel samples, as observed for all the analysed coal variants. On the surfaces of the samples seasoned in the presence of claystones, highly varied forms of damage were observed: microcutting, scaly surface cracks, delamination, and deep cracks. In these cases, it was possible that the abrasive grains had been pressed into the steel surface irregularities, but no layered forms of the pressed-in abrasive material were observed to have developed. The paper also presents a model for the formation of coal films and discusses their possible effect on wear minimisation.

Abrasive Wear of Mining Chain Drums Made of Austempered Ductile Iron in Different Operating Modes.

The paper presents results of testing the resistance of chain wheels made of alloyed austempered ductile iron (ADI) with various content of retained austenite and subjected to shot peening, to the dynamic and abrasive wear by solid particles. The impact of the additional environmental factor-external dynamic forces-accompanying the operation of the chain wheels in the presence of the quartz particles has a synergistic effect on the abrasive wear in the contact area between the wheels and the chain links for all the considered variants, except for the ADI with the structure of the upper ausferrite. Based on the results obtained, it was found that the abrasive wear by solid particles increased and that the hardness of the surface layer of the chain wheels subjected to shot peening decreased. The relative increase in the wear ΔVDYN/δMAX,(A), representing the share of the additional dynamic force in the process of wear, was in the range of 16-40% for the group of tested cast iron ADI not subjected to shot peening, while for the shot peened-in the range of 16-64%. Demonstration of phase changes during the operation of chain wheels and the change in their intensity depending on the combination of environmental factors is the work novelty. In the opinion of the authors, the presented results will be of great practical importance as they will allow to increase the knowledge on the proper selection of ADI cast iron for environmental conditions.

A Complex Vibration Analysis of a Drive System Equipped with an Innovative Prototype of a Flexible Torsion Clutch as an Element of Pre-Implementation Testing.

The paper presents how an important aspect of introducing new machines, especially in the mining industry, is testing a prototype under laboratory conditions. For this purpose, advanced methods of analyzing the vibrations of a drive system equipped with an innovative prototype of a flexible torsion clutch are presented. The main goal is to present a comprehensive method for analyzing vibration signals in various dimensions of the signal analysis. As a result of this approach, it can be seen how much important information about the tested clutch can be obtained by using various analysis methods in terms of time-frequency distributions or order analysis. To emphasize the differences in the functioning of the tested clutch and the possibility of monitoring these differences on the basis of the observation of residual processes, such as vibrations, the results for the flexible and locked clutch are compared.

Research on Vibroactivity of Toothed Gears with Highly Flexible Metal Clutch under Variable Load Conditions.

The article provides a discussion on a methodology intended for testing of power transmission systems featuring an innovative highly torsionally flexible metal clutch patented by the co-authors of this paper. What this methodology takes into account is the amplitude and frequency analyses discussed in the article, as well as a sensing system based on diverse piezoelectric and magnetic phenomena, the Doppler effect, etc. Both contact and non-contact (laser measurement) methods were used during the tests. The purpose of the tests conducted at the stand, originally designed by the authors in accordance with the methodology proposed, was to evidence that using the innovative and patented, highly torsionally flexible metal clutch makes it possible to reduce the vibrations of multi-stage toothed gears, consequently reducing the forces affecting the gear bearings and those acting at the tooth space, which is to enable the service life of individual components of the power transmission systems intended for mining scraper conveyors to be significantly extended. Based on the studies and analyses performed by the authors, one can observe and conclude that the methodology proposed in the paper makes it possible to use an example of a relatively complex power transmission system in order to examine the relationships between the processes at work, i.e., the decline of the linear vibrations of the gear housing (which is undoubtedly positive in power transmission systems) at the expense of increasing torsional vibrations of the innovative clutch, the latter not to be considered unfavourable to users in the case analysed.

Multidimensional Data Interpretation of Vibration Signals Registered in Different Locations for System Condition Monitoring of a Three-Stage Gear Transmission Operating under Difficult Conditions.

This article provides a discussion of the results of studies on the original system condition monitoring of a three-stage transmission with a bevel-cylindrical-planetary configuration installed in an experimental scraper conveyor. Due to the high vibroactivity of gear transmissions operating under the impact of a scraper conveyor's chain drive, these unwanted effects of machine operating vibrations were assumed to be applied. For purposes of the study, vibrations were measured on the driving transmission housing in an idling scraper conveyor. The main purpose of the study was to establish the frequencies characteristic of the gear transmission, and to determine whether it was possible to run vibroacoustic diagnostics of the same transmission under conditions with a considerable impact of the conveyor chain. An additional cognitively significant research goal was the analysis of the dependence of the diagnostic utility of the signal depending on the sensor mounting point. Five different locations of three-axis sensors oriented to the next stages and various types of gears were determined, as well as places characterized by high spatial accessibility, which are often selected as places for measuring the vibration of gears. Using MATLAB software, a program was written that was calibrated and adapted to the specifics of the measuring equipment based on the collected test results. As a result, it was possible to obtain a multidimensional data interpretation of vibration signals of system condition monitoring of a three-stage gear transmission operating under difficult conditions. The results were based on signals registered on the real three-stage gear transmission operating under the impact of a scraper conveyor's chain drive.

Abrasive Wear, Scuffing and Rolling Contact Fatigue of DLC-Coated 18CrNiMo7-6 Steel Lubricated by a Pure and Contaminated Gear Oil.

Due to extreme working conditions of mining conveyors, which contaminate gear oil with solid particles, their transmissions are exposed to intensive abrasion, scuffing, and even rolling contact fatigue (pitting). These effects shorten gear life. To prevent their occurrence, a wear-resistant coating can be deposited on gear teeth. The resistance to abrasive wear, scuffing, and pitting was investigated and reported in the article. Simple, model specimens were used. Abrasive wear and scuffing were tested using a pin-and-vee-block tribosystem in sliding contact. A cone-three-ball rolling tribosystem was employed to test pitting. The material of the test specimens (pins, vee blocks, cones) was 18CrNiMo7-6 case-hardened steel. Two types of DLC (Diamond-like Coatings) coatings were tested, W-DLC and W-DLC/CrN. The vee blocks and cones were coated. Two industrial gear oils were selected to lubricate the specimens: one with a mineral and one with a synthetic PAO (polyalphaolephine) base, as pure oil or contaminated with solid particles from a coal mine. The results show that, to minimize the tendency to abrasion, scuffing, and pitting of specimens made of 18CrNiMo7-6 steel, the W-DLC/CrN coating should be deposited. This coating also gives very good protection when the lubricating oil is contaminated.

Are There Differences in Concentric Isokinetic Strength Perfor-Mance Profiles between International and Non-International Elite Soccer Players?

The purpose of this study is to evaluate the differences in concentric isokinetic strength characteristics of the knee extensor and knee flexor musculature between international (IL) and non-international level (N-IL) soccer players. The second aim is to establish strength symmetry status in knee muscles for dominant (DL) and non-dominant (NDL) legs for both within and between groups. 100 male top elite soccer players (IL: n = 36, age = 27.5 ± 3.4 years and N-IL: n = 64, age = 27.7 ± 6.4 years) underwent concentric isokinetic strength tests, using a Biodex System 3 dynamometer. Results indicate that statistically significant differences between groups were noted for peak torque of hamstrings (PT-H), hamstrings/quadriceps (H/Q) ratio, and total work of hamstrings (TW-H), where mean values for the IL were similarly higher than for the N-IL group (p = 0.006, p < 0.001, and p = 0.012, respectively). Our results also showed statistically significant differences for peak torque of quadriceps (PT-Q), PT-H, total work of quadriceps (TW-Q) and TW-H between legs, where mean values noted for the DL were higher than for the NDL for both groups (p = 0.021, p < 0.001, p = 0.006, and p = 0.004, respectively). Additional results show that IL players presented more symmetrical strength between legs than N-IL. The results of this study indicate that that the greatest differences in isokinetic strength performance across players at different soccer levels relate to the hamstring muscle. As a result, systematic strength training of these muscle groups is strongly recommended.

Jumping Height Does Not Increase in Well Trained Volleyball Players After Transcutaneous Spinal Direct Current Stimulation.

Transcutaneous spinal direct current stimulation (tsDCS) increases corticospinal and spinal reflex excitability, and may be a new tool for increasing muscle explosive performance in sports training. The aim of the study was to evaluate whether tsDCS can enhance jumping ability in trained humans practicing volleyball. Twenty eight participants completed the study, including 21 men and 7 women. We investigated the effects of a single 15-minute session of sham, anodal, and cathodal tsDCS over spine and shoulder on repeated counter movement jump (CMJ) and squat jump (SJ) performance at 0, 30 and 60 min post-stimulation. The order of SJs and CMJs sets in each session was randomized. Each SJ and CMJ set consisted of 3 jumps. The break between each attempt was 1 min and the interval between the sets was 3 min. Two-way repeated measures ANOVA did not show effect of time, nor stimulation method, nor stimulation method × time interactions on SJ (time: F ( 1 . 8,142 . 1 ) = 1.054; p = 0.346, stimulation: F ( 2,78 ) = 0.019; p = 0.981, stimulation × time: F ( 3 . 6,142 . 1 ) = 0.725; p = 0.564) or CMJ (time: F ( 1 . 8,140 . 9 ) = 2.092; p = 0.132, stimulation: F ( 2,78 ) = 0.005; p = 0.995, stimulation × time: F ( 3 . 6,140 . 9 ) = 0.517; p = 0.705) performance. Single session of tsDCS over spine and shoulder does not increase jumping height in well-trained volleyball players. This is an important finding for coaches and strength conditioning professionals for understanding the practical utility of tsDCS for enhancing muscular explosiveness.

Analysis of static balance performance and dynamic postural priority according to playing position in elite soccer players.

BACKGROUNDS: Balance performance and postural priority are important components of motor skill development. No published reports have investigated the differences in static balance abilities and postural priority among professional soccer players according to field position. RESEARCH QUESTION: We hypothesized that static balance as well as dynamic postural priority is influenced by playing position in professional soccer players. METHODS: The study covered a group of 101 elite professional soccer players who were divided into six subgroups according to playing positions: goalkeepers (G) (n = 10), central defenders (CD) (n = 15), external defenders (ED) (n = 15), central midfielders (CM) (n = 23), external midfielders (EM) (n = 15) and forwards (F) (n = 23). All participants completed the Delos Postural System Test using the standard protocol. The tests were performed unilaterally on non-dominant (NL) and dominant leg (DL) under static conditions (with open and closed eyes) standing on a stable platform and under dynamic conditions on an unstable base. RESULTS: In the static test with open eyes (ST OE) there were no statistically significant differences between the legs and positions. In the static test with closed eyes (ST CE), the differences are statistically significant only between positions. Players on the CM position have significantly higher differences than G. In the dynamic postural priority test (DPPT) there is a difference between positions and legs. In fact, the statistically higher differentiation refers to players in the CM position relative to ED, CD, EM and F. We noticed a significantly greater difference in the NL compared to the DL. SIGNIFICANCE: Static balance performance and postural priority varied with playing position in elite soccer players. Midfield players have better postural priority than players in other positions. Professional soccer players present greater balance postural priority on the non-dominant leg.

Testicular Sonographic Color Doppler Dynamic Tissue Perfusion Measurements in Adolescents with Varicocele.

AIM: The aim of the study was an assessment of the effects of varicocele on testis parenchyma and microcirculation with the use of the dynamic tissue perfusion measurements. METHODS: Color Doppler sonographic dynamic testis parenchyma perfusion measurements were performed with Pixel-Flux software in 30 children with left testis varicocele. The right testes without varicocele comprised the control group. RESULTS: Testicular parenchymal perfusion in testes with varicocele was reduced when compared to the control testes. The differences were found in all measured perfusion parameters. Statistical significance was found in the case of mean velocity and resistance index parameters. According to the grade of varicocele, the perfusion was the most reduced in patients with grade III of varicocele. CONCLUSION: Testicular parenchymal perfusion decreases in patients with varicocele, mostly in higher grades of varicocele. In case of validation, the method can be used in determining the damage of the testis with varicocele and the need for surgery.

Nuck Canal Hernias, Typical and Unusual Ultrasound Findings.

BACKGROUND: Inguinal hernia in girls is a very rare condition. The cause of this pathology is incomplete closure of the processus vaginalis of the peritoneum, in girls named the canal of Nuck. Failed obliteration of this canal could result in hernia or hydrocele. Also less frequent findings, such as uterus herniated to the canal, were observed. OBJECTIVE: The purpose of this study was to describe the possible findings in female inguinal hernias and its ultrasound appearance. METHODS: Thirty-five patients with surgically confirmed hernias of the canal of Nuck were identified at our institution between January 2007 and November 2015. All the patients underwent ultrasonography before surgery. RESULTS: In 14 cases, there was hydrocele of the canal of Nuck. In 9 cases, intestinal hernia was found. In 10 patients, the hernia content appeared as mass-containing cysts and was confirmed at surgery as ovary. In 1 patient, the ovary was herniated together with uterus. In 1 patient, atypical hypoechoic lesion was found, which turned out to be angiofibrolipoma. In all patients, ultrasound diagnosis was confirmed by surgery. CONCLUSIONS: Ultrasound examination performed with high-frequency transducer is an examination of choice in female patients with pathological mass in inguinal region.

The use of testicular prostheses in boys.

Lack of the testis is an important factor in psycho-sexual development of the boys, and implantation of the prosthesis plays a very essential role in the treatment of that group of patients. Currently there are no standards regarding when prosthesis should be implanted, and which access is connected with minimal rates of complications. We present our experience of primary prosthesis implantations in boys treated in our department.From 2000 to 2014, primary implantation of the testicular prosthesis was performed in 290 boys. The early and late post-operative complications and long-term therapeutic results were analyzed, considering age at the time of implantation, the time between the initial operation and implantation of the prosthesis, and the surgical approach.Best results were observed in 267 patients and bad outcome in 23 patients. Prosthesis implantation in young boys operated within the first three years of life or during the first year after primary surgery was connected with statistically fewer complications (P = .002 and P < .05, respectively). Supra-scrotal access was connected with the lowest rate of complications (P = .01).Long-term therapeutic results in boys with testicular prostheses were good in the majority of cases. Implantation of the first prosthesis should be performed early between 1 and 3 years of life in boys with lack of the testis. Implantation of a prosthesis should also be performed within 1 year after removing of testis or during orchiectomy. Supra-scrotal access should be chosen for testicular prosthesis implantation due to the best long-term results.

Ultrasound image of malignant bone tumors in children. An analysis of nine patients diagnosed in 2011-2016.

INTRODUCTION: The diagnostic process of bone tumors, including malignant ones, is based on conventional radiological methods, such as radiography and computed tomography, and with precise assessment of local advancement in magnetic resonance imaging. Ultrasonography is not included in the diagnostic algorithms as a tool suitable to detect this type of pathology. More and more frequent usage of musculoskeletal ultrasound in children as the first imaging method or, in some cases, as the only diagnostic method, makes it necessary to be familiar with sonographic presentation of bone tumors to suggest this diagnosis early enough and, after its verification, start treatment without a significant delay. Aim: The aim of this study was to determine changes in the sonographic image that might indicate a bone malignancy and suggest the need to extend the diagnostic process in this direction. MATERIAL AND METHOD: This article discusses 10 bone tumors in 9 children who had an ultrasound scan performed at the beginning of the diagnostic process before the histopathological diagnosis was established and treatment initiated. The assessment involved ultrasonographic features indicating the presence of a tumor. Results: In the group of 9 patients, 8 malignant bone tumors were diagnosed in ultrasonography and later verified histopathologically: 4 osteosarcomas and 4 Ewing's sarcomas. In one case, two bone tumors were detected in ultrasonography without specification of their nature (malignant/benign, primary/secondary). MATERIAL AND METHOD: In the analyzed cases, ultrasonography enabled the correct diagnosis of a focal bone lesion, and in most cases (8/9) it presented an image that suggested its malignant nature and the necessity of further diagnosis and treatment.

3D/4D contrast-enhanced urosonography (ceVUS) in children - is it superior to the 2D technique?

BACKGROUND: By now, two-dimensional contrast-enhanced voiding urosonography (ceVUS) has become a well-established method for the diagnosis and treatment monitoring of vesicoureteral reflux in children, particularly after the recent approval for this application in children in the USA and in Europe. The introduction of three-dimensional static (3D) and real-time (4D) techniques with ultrasound contrast agents opens up new diagnostic opportunities for this imaging modality. OBJECTIVE: To analyze whether 3D and 4D ceVUS is a superior technique compared to standard 2D ceVUS in diagnosing vesicoureteral reflux in children. MATERIAL AND METHODS: The study included 150 patients (mean age 3.7 years) who underwent 2D and 3D/4D ceVUS for the diagnosis and grading of vesicoureteral reflux. RESULTS: 2D ceVUS and 3D/4D ceVUS diagnosed the same number of vesicoureteral refluxes, however, there was a statistically significant difference in grading between the two methods. Performing 3D/4D ceVUS resulted in changing the initial grade compared to 2D ceVUS in 19 out of 107 refluxing units (17.76%) diagnosed. The 4D technique enabled a more conspicuous visualization of vesicoureteral reflux than the 3D technique. CONCLUSIONS: 2D ceVUS and 3D/4D ceVUS diagnosed the same number of vesicoureteral refluxes, however, there was a statistically significant difference in grading between the two methods. Thus 3D/4D ceVUS appears at least a valid, if not even a more conspicuous technique compared to 2D ceVUS.

Variation in geographical treatment intensity affects survival of non-small cell lung cancer patients in England.

OBJECTIVES: We aimed to determine the geographical variation in the proportion of non-small cell lung cancer (NSCLC) patients undergoing curative treatment and assess the relationship between treatment access rates and survival outcomes. METHODS: We extracted cancer registration data on 144,357 lung cancer (excluding small cell tumours) patients diagnosed between 2009 and 2013. Surgical and radiotherapy treatment intensity quintiles were based on patients' Clinical Commissioning Group (CCG) of residence. We used logistic regression to assess the effect of travel time and case-mix on treatment use and Cox regression to analyse survival in relation to treatment intensity. RESULTS: There was wide variation in the use of curative treatment across CCGs, with the proportion undergoing surgery ranging from 8.9% to 20.2%, and 0.4% to 16.4% for radical radiotherapy. The odds of undergoing surgery decreased with socioeconomic deprivation (OR 0.91, 95% CI 0.85-0.97), whereas the opposite was observed for radiotherapy (OR 1.16, 95% CI 1.08-1.25). There was an overall effect of travel time to thoracic surgery centre on the odds of undergoing surgery (OR 0.81, 95% CI 0.76-0.87 for travel time >55 min vs ≤15 min) which was amplified by the effect of deprivation. No clear association was observed for radiotherapy. Higher mortality rates were observed for the lower resection and radiotherapy quintiles (HR 1.08, 95% CI 1.04-1.12 and HR 1.06, 95% CI 1.02-1.10 for lowest vs. highest resection and radiotherapy quintile). CONCLUSION: There was wide geographical variation in the use of curative treatment and a higher frequency of treatment was associated with better survival.

Six-Year Experience in Teaching Pelvic Floor Ultrasonography Using Pelvic Floor Phantoms.

OBJECTIVE: To review our 6-year experience (2009-2015) in teaching three-dimensional pelvic floor ultrasonography workshops that utilized pelvic floor phantoms in the setting of an Objective Structured Assessment of Technical Skills methodology. METHODS: Four-hour Objective Structured Assessment of Technical Skills workshops were given at several society meetings and involved a didactic session, a hands-on session using the pelvic floor phantoms, and a computer station session reviewing pelvic floor pathologies. We analyzed improvement in participants' diagnostic skills using a test with 60 illustrated questions of normal and pathologic findings in live human models. RESULTS: Two hundred forty-three attendees completed the 60-question test before and after attending the workshop. Paired t test showed a significant improvement in attendees' average scores after the workshop in all categories: anatomy, normal, or pathologic endovaginal imaging and normal or pathologic endoanal imaging (P<.001 for all). McNemar test showed a statistically significant increased number of correct answers in 50 of 60 (83%) questions. CONCLUSION: Our Objective Structured Assessment of Technical Skills workshops incorporating pelvic floor phantoms enhanced trainees' pelvic floor ultrasound diagnostic skills.

The relationship between jumping performance, isokinetic strength and dynamic postural control in elite youth soccer players.

BACKGROUND: The aim of this study was to investigate the relationship between vertical jumping performance, isokinetic strength of knee extensors/flexors, and postural priority and to describe a multiple regression model that accounts for the effects of selected parameters of isokinetic strength and postural priority on vertical jumping performance. METHODS: Thirty-one professional male soccer players, aged from 17 to 20 years, participated in this study (age, mean±SD: 18.6±1.26 years; height: 1.78±0.74 m and weight: 73.1±6.77 kg). The correlations between isokinetic knee strength, jumping performance, and postural control were evaluated using the Pearson correlation coefficient. A linear regression model was used to evaluate the effect of hamstrings and quadriceps peak torque of both legs at 60º·s-1, total work of both legs at 240º·s-1, and postural priority on jumping performance. RESULTS: The peak torque of right leg knee flexor (quadriceps) muscles, evaluated at 60º·s-1 speed, showed correlations with counter movement jump, 30 second jumping and squat jump (P=0.005, P=0.003, and P=0.007, respectively). We also observed a strong relationship between counter movement jump and 30 second jumping and peak torque of left leg evaluated at the same speed of 60º·s-1 (P=0.26 and P=0.22, respectively). No significant correlations were found between any of the jumping tests and peak torque of knee extensors of both legs at 60º·s-1. For the 30 second jumping test, it appears that jumping endurance has a significant relationship with total work of knee flexors for right and left legs at 240º·s-1. CONCLUSIONS: The results of this study demonstrate practical implications for soccer performance, but further exploration is required.