Easy Way To Determine The Feasibility Of Coarse Aggregate On All Pavement Layers Using The Los Angeles Tatonas TA-700 Machine

The use of coarse aggregate with poor quality can cause bumpy roads, cracked roads, potholes, and others. Coarse aggregate wear is an indicator of the aggregate resistance index against friction with other objects. Any aggregate to be used in a pavement mix must meet the wear requirements. Low wear causes the aggregate to be easily crushed when exposed to friction and has an impact on a low level of stability. The purpose of this research is to determine the feasibility of coarse aggregate in Kedak Village, Kediri. One of the feasibility of coarse aggregate is reviewed based on wear with abrasion testing. This research was conducted by using an abrasion test using the Los Angeles TA-700 machine and SNI 2417:2008 as a reference. The specimens were taken at random and met the criteria for passing the number 3/4 sieve and stuck on the 2500 gram sieve number 1/2 and the aggregate that passed the 1/2 sieve was stuck on the 3/8 sieve as much as 2500 grams. The results obtained stated that the average wear of the abrasion test was 26.6%. Based on these results, the aggregate can be said to be feasible because it does not exceed 40% in accordance with the provisions of the 2018 Binamarga General Specifications. So that coarse aggregate from Kedak Village, Kediri can be used for all mixtures of road pavement layers.

Physical and economic impacts of studded tyre use on pavement structures in cold climates

ABSTRACT In cold regions like Alaska of USA, Canada and the northern parts of Europe, using studded tyres is common among the public when driving in icy and snowy conditions. However, studded tyres cause extensive wear to asphalt pavement, reducing pavement life. This study addresses the physical and economic impacts of winter studded tyres on the roadway system to better inform decision makers as they develop alternative solutions and future polices. The approach is applied in a case study from a sample of Alaska statewide road segments. Surveys were employed to examine the extent of the use of studded tyres and cost-effective alternatives. A pavement life-cycle cost review was established considering several variables to discover a realistic cost of roadway resurfacing and rehabilitation. Wear rates due to studded tyres and rut rates due to wheel loads were found for different highway classes. The results indicate higher average wear rates due to studded passenger vehicles on freeways than average rut rates due to heavy wheel loads. The results also indicate lower average wear rates on arterial and collector roads. The estimates show that studded tyre use reduced asphalt surface life by about 7 years on the selected freeway sample in the case study, which is about 47% loss in pavement life based on the initial design life of 15 years. Other road classes experienced lower reductions in service life. Finally, cost analysis was provided to reflect the impact of studded tyres on the state's budget. Countermeasures were suggested, which in turn may help other cold regions develop strategies on the use of new winter tyre technology.

Characterization and Tribological Performances of Graphene and Fluorinated Graphene Particles in PAO

Graphene has been widely used as a lubricating additive to reduce the energy consumption of engines and improve fuel economy because of its unique crystal structure. Herein, graphene (GR) and fluorinated graphene (F-GR) nanoparticles were prepared by ball milling and liquid-phase exfoliation. The SEM/EDS, HRTEM, XPS, Raman spectrometer, X-ray spectrometer, FTIR were used to investigate the morphologies, surface groups, and crystal structure of two kinds of graphene materials. The influence of loads on the tribological properties of two kinds of particles was investigated in Poly Alpha Olefin (PAO6) using a UMT-2 reciprocating tribometer. Results showed that the crystal structure of GR is better than F-GR. F-GR can improve the lubrication performance of PAO6. For PAO6 containing 1 wt% F-GR at 10 N, the average friction coefficient and average wear rate decreased by 12.3% and 87% relative to pure PAO6, respectively. However, the high load resulted in an inconspicuous anti-wear and anti-friction effect. The influence of F-GR on the tribological behavior of PAO6 was more substantial than that of GR. The friction and wear mechanisms attributed to F-GR quickly entered the interface between the friction pairs. Friction-induced F-GR nanosheets mainly took the tribo-chemical reactions to participate in the lubrication film formation and helped achieve a low friction coefficient and wear rate.

Some Regularities of Life Time and Damage for the New Structural Material MoNiCa during Sliding Friction and Mechano-Sliding Fatigue

The results of an experimental study of damage for the structural material MoNiCa (it is high-strength cast iron VCHTG – patent of the Republic of Belarus № 15617) on sliding friction and mechano-sliding fatigue are analyzed in the report. Tests of the mechanical system shaft (a sample with a working part diameter of 10 mm made of 0.45 % carbon steel) - an insert (a prismatic counter sample with a cross section of 10 ´ 10 mm made of MoNiCa) were carried out. The kinetics of the change in average wear at 8 local points along the perimeter of the dangerous area of the sample is given for contact loads FN from 20 to 92 N of the mechanical system under study with MoNiCa inserts without heat treatment and with heat treatment. The test results of the system under study are also presented in the form of sliding friction and mechano-sliding fatigue curves in coordinates of the contact load FN – the number of cycles N until the limit state.

Wearable Cardioverter Defibrillator (WCD) in Italy: results from the nationwide multicenter registry WEAR-ITA

Funding Acknowledgements Type of funding sources: None. BACKGROUND The Wearable Cardioverter Defibrillators (WCD) has been used extensively in Italy since 2015, following long years of experience in other countries. This technology provides temporary protection from Sudden Cardiac Death (SCD) for patients with an evolving risk profile that may not yet be eligible for an Implantable Cardioverter Defibrillator (ICD). Collecting national data on use of the device can help build a picture that will enable an understanding on how to use the WCD appropriately in the future. PURPOSE Our purpose has been to investigate WCD usage on a nationwide level. This is in terms of target population, average wear time, patient compliance, diagnosed and treated arrhythmic events and patient outcome once they stopped wearing the device. METHODS WEAR-ITA is a nationwide, multi-centre retrospective observational project. Patient data was retrospectively collected from the Italian hospitals that agreed to take part in the data collection for all patients fitted with a WCD between April 2015 to May 2018. All data refers to the range from the first day of wear until the end of use. RESULTS We collected data for 411 patients from 15 (75%) Italian regions. WCD use among the different regions was heterogeneous with a median of 0.5 (0.2-1.2) WCD wore/105 inhabitants. The mean age of the population was 55(±14) and the majority of patients were male (79%). Main WCD indication was non-ischemic cardiomyopathy with reduced ejection fraction (51%), ischemic etiology with severe systolic dysfunction (31%), uncertain or unidentified diagnosis (10%) that then revealed to be predominantly channelopathies or myocarditis and after ICD extraction (8%). Patients wore the WCD for a median of 59 (33-90) days and the median daily weartime was 23 (22,7-23,8) hours. In 15 patients (4%), the WCD recorded non sustained ventricular tachycardia (VT), 10 patients (2%) had hemodynamically well-tolerated sustained VT not needing a shock. 8 patients (2%) received effective appropriate shocks. Time to episodes were respectively 61 (14-61) days for non-sustained VT and 28 (19-70) days for VT/VF. 2 patients (0.5%) received inappropriate shocks for sinus tachycardia and atrial fibrillation (AF) respectively. WCD recorded new onset of supra ventricular tachycardia episodes in 12 patients (3%) and of atrial fibrillation (AF) in 7 patients (2%). 7 patients (2%) died while wearing WCD; none of them from SCD. At the end of the WCD use, 195 patients (47%) did not receive an ICD while 209 patients (51%)were implanted. CONCLUSIONS WCD is an effective therapy for the treatment of SCD with a very low complication rates. The indication and penetration in Italy is quite heterogeneous. The patient’s compliance is high over time. The incidence of appropriate shock is not negligible; only half of patients, who wore WCD, received an ICD. There is however still a requirement to conduct further randomized trials to understand which patients could most benefit from the use of WCD. Abstract Figure. Wereable Cardioverter Defibrillator

Designing a Bioinspired Surface for Improved Wear Resistance and Friction Reduction

This study used 2-photon 3D lithographic printing and replica molding to fabricate a micro-texture based on the Ocellated Skink. The fabricated surface texture was studied for friction and wear behavior using linear reciprocating tribological tests with a chrome steel ball counterface under various loading conditions and compared to samples fabricated with the same methods without a surface texture. The texture was found to decrease friction at low loads and provide steady friction under all loading conditions. The textured samples also decreased the average wear track width up to 61%. Wear was reduced on surfaces by the texture through the controlled formation of microcracking, which both reduced the amount of debris built up on samples and effectively reduced the worn area.

Predictive Modeling of Surface Wear in Mechanical Contacts under Lubricated and Non-Lubricated Conditions

The surface wear in mechanical contacts under running conditions is always a challenge to quantify. However, the inevitable relationship between the airborne noise and the surface wear can be used to predict the latter with good accuracy. In this paper, a predictive model has been derived to quantify surface wear by using airborne noise signals collected at a microphone. The noise was generated from a pin on disc setup on different dry and lubricated conditions. The collected signals were analyzed, and spectral features estimated from the measurements and regression models implemented in order to achieve an average wear prediction accuracy of within 1mm3.

Mathematical Model of Influence of Geometric Parameters on Wave Gear Teeth Wear

The object of the research is a wave gear with a cam wave generator. One of the requirements for wave gears is to increase the wear resistance of the teeth flanks. A mathematical model that makes it possible to assess the influence of the geometrical parameters of the gear on the teeth wear is proposed in this work. To assess the specified effect, the maximum and average wear coefficients are introduced. To calculate these coefficients, a spatial mathematical model of a wave gear is used, taking into account the volumetric and contact deformations of gear wheels and a flexible bearing. Using the developed technique, the dependences of the wear coefficients on the radial deformation and the length of the flexible gear were obtained. The given dependences increase the knowledge concerning the influence of geometric parameters on the wave gear teeth wear.

MEASURES TO ENSURE THE SAFETY AND OPERATIONAL RELIABILITY OF THE FUNCTIONING OF IRRIGATION AND DRAINAGE SYSTEMS WITH A LONG SERVICE LIFE

The issues of ensuring the safety and operational reliability of the functioning of irrigation and drainage systems with a long service life are considered. It has been established that the service life of irrigation and drainage systems in the south of Russia is about 40-50 years, the average wear is 72%. In the Krasnodar territory the rate of wear of reservoirs, ponds and canals is about 80-100% which indicates to a signifi cant siltation and loss of throughput capacity. Depreciation of dams and dikes is 35-40%. The main damages of the HTS are erosion of the upper slope, malfunction of the spillway and silting of the reservoir bowl (pond) which leads to increased filtration through the dam body, an increase in the level of the depression curve and complication of the passage of fl ood water. Changes in the rules for the operation of hydraulic structures, in particular, a decrease in the normal retaining level in comparison with the design level is not a rare occurrence. At the same time, the HTS operation in the sparing mode can be considered a temporary measure used until repair or reconstruction is carried out. The operational efficiency of hydraulic structures with a high degree of wear at the level of ultimate loads and impacts below the design values is noticeably getting reduced. The use of constant monitoring, as well as forecasting the reliability of hydraulic structures, can reduce the severity of the problem. Safe and effi cient operation of hydraulic structures with a high degree of wear during the period preceding repair or reconstruction can be ensured by introducing a system for automated monitoring of hydraulic structures in combination with a decision support system (DSS).

PENGARUH PROSES HARDENING BAJA AISI 1045 TERHADAP SIFAT KEAUSAN

AISI 1045 steel is a steel classified as medium carbon alloy steel which is widely used as the main material in machinery so it must have good mechanical properties such as hardness, wear resistance. The purpose of this study was to determine the effect of heat treatment on the wear rate of AISI 1045 steel. The research method used was AISI 1045 steel which was given a hardening heat treatment with a temperature variation of 800ºC, 850ºC, 900ºC with a holding time of 60 minutes, followed by rapid cooling using water . after that the specimen will be tested for wear by using a standard Pin On Disc. the results of the study show that the wear value at 800ºC has an average wear value of 15.0762 mg / cm², then at a temperature of 850ºC has an average wear value of 11.33933 mg / cm² and at a temperature of 900ºC has an average wear value of 9 9488 mg / cm². In conclusion, there was a very strong influence on the use of hardening temperature variations on the AISI 1045 steel wear and the smallest wear value on the specimen given by the hardening process at 900ºC with an average wear value of 9.9488 mg / cm².