Evaluation of torque moment in esthetic brackets from bendable alloy wires

ABSTRACT Objectives To examine the torque moment that occurs between esthetic brackets and bendable alloy (stainless steel [SS], titanium-molybdenum [Ti-Mo], and titanium-niobium [Ti-Nb]) wires. Materials and Methods This study examined ceramic (CR), zirconium oxide (ZC), polycarbonate (PC), and conventional metallic brackets (MT) (upper, 0.018-inch and 0.022-inch slots) combined with SS, Ti-Mo, and Ti-Nb wires using elastic module ligation. The torque moments delivered by various wire and bracket combinations were measured using a torque gauge apparatus. The wire torque angles at 5–40° were examined. Results The torque value increased in the order of CR, ZC, MT, and PC brackets for both 0.018-inch and 0.022-inch slots. The fracture points of the CR and ZC brackets combined with SS and Ti-Mo wires were approximately more than 30° and 35°, respectively. No fracture points were detected in the combination of ZC brackets and Ti-Nb wires. Conclusions The current study identified the material characteristics of CR, ZR, and PC brackets during torque tooth movements. The present results demonstrate a characteristic combined effect between different esthetic brackets and bendable alloy wires.

Improving the design of an internal combustion engine with counter pistons

A new layout of a two-cylinder internal combustion engine with counter-pistons is proposed, which increases its efficiency by reducing the pressure angles. The dynamics of the proposed arrangement of a two-shaft crank-slider internal combustion engine, which provides maximum torque moment at maximum gas pressure in the minimum volume of the combustion chamber, is investigated, which reduces the load on the engine design and its weight and dimensional parameters. The research was carried out by comparing the dynamic characteristics of different engines using vector modular models and the KDAM program. Keywords: internal combustion engine, crank mechanism, indicator diagram, dynamic characteristics, torque moment, vector, contour, model, module [email protected]

Calculation of interference fits under combined loading

At determining the interference fits using conventional methodic the loads acting on a joint such as torque moment and axial force are taken into account. It is shown that it is necessary to take into account also the radial and cantilever loads. An example of calculating the fit of a bevel gear on a shaft under combined loading is considered. Keywords: interference, fit, limit interference, tolerance, radial force, cantilever load. [email protected]

Usefulness of Hulled Wheats Grown in Polish Environment for Wholegrain Pasta-Making

The best pasta raw material is durum wheat (Triticum turgidum subsp. durum (Desf.) Husn.). Recently, old wheat species have also attracted interest. The aim of the study was to evaluate their usefulness for industrial pasta production. The technological characteristics of grains and the organoleptic characteristics of pasta obtained from hulled emmer (T. turgidum subsp. dicoccum) and spelt (T. aestivum ssp. spelta) were determined and compared to durum wheat, as a standard pasta raw material, and common wheat (T. aestivum). All wheats were grown under identical conditions. The hardness of kernels was assessed using the practical size index, wheat hardness index, torque moment, milling work of 50 g of flour, semolina yield, and starch damage. The technological and nutritional values of semolina, i.e., protein and ash content, wet gluten yield and quality, and falling number, were determined. Moreover, the organoleptic characteristics of cooked pasta were analysed in terms of appearance, colour, taste, smell, and consistency. The milling parameters of emmer were comparable to those of durum wheat; moreover, the content of protein, gluten, and ash was higher in emmer. Spelt was found to be similar to common wheat. Hulled wheats, especially emmer, show good quality parameters and can be an alternative raw material for industrial pasta production.

TEST RESULTS FOR BALL-BEARINGS IN THE DRIVES OF SYSTEMS AND SCIENTIFIC EQUIPMENT OF A SPACECRAFT IN OSCILLATORY OPERATIONAL MODE

This paper aims at elucidating some special operational aspects of instrument ball bearings used in systems and scientific equipment of a spacecraft in oscillatory mode in vacuum with the lubricant VNII NP-274n. The service life of such bearings is mostly determined by the lubrication mode, as well as anti-torque moment, which is an indicator of internal energy losses. To observe these parameters in the course of bearings operation in oscillatory mode in vacuum an electromechanical test rig was set up. The test data obtained in oscillatory mode were compared with data obtained during continuous rotation of the same bearings. Based on the results of the tests, a lubricating mode was determined, an empirical formula was proposed for the relationship between the anti-torque moment and oscillatory motion parameters, as well as recommendations on extending the service life were provided. The paper may be of use to developers of systems and scientific instrumentation of a SC with oscillating shaft, which uses as supports ball bearings with predominantly axial load. Key words: spacecraft life, oscillatory motion, rotational resistance, lubrication mode, inertial slippage

Critical Output Torque of a GHz CNT-Based Rotation Transmission System Via Axial Interface Friction at Low Temperature

It was discovered that a sudden jump of the output torque moment from a rotation transmission nanosystem made from carbon nanotubes (CNTs) occurred when decreasing the system temperature. In the nanosystem from coaxial-layout CNTs, the motor with specified rotational frequency (ωM) can drive the inner tube (rotor) to rotate in the outer tubes. When the axial gap between the motor and the rotor was fixed, the friction between their neighbor edges was stronger at a lower temperature. Especially at temperatures below 100 K, the friction-induced driving torque increases with ωM. When the rotor was subjected to an external resistant torque moment (Mr), it could not rotate opposite to the motor even if it deformed heavily. Combining molecular dynamics simulations with the bi-sectioning algorithm, the critical value of Mr was obtained. Under the critical torque moment, the rotor stopped rotating. Accordingly, a transmission nanosystem can be designed to provide a strong torque moment via interface friction at low temperature.

Evaluation of Flange Calculations Using Strain-Based Acceptance Criteria

The Nuclear Power Plant KKG in Gösgen, Switzerland was designed according to the ASME Boiler and Pressure Vessel Code. The ASME BPVC, Section III, Appendix 11 regulates the flange calculation for class 2 and 3 components, it is also used for class 1 flanges. A standard for the determination of the required gasket characteristics is not well established which leads to a lack of clarity. As a hint different y and m values for different kinds of gasket are invented in ASME BPVC Section III [1]. The KTA 3201.2[2] and KTA 3211.2[3] regulate the calculation of bolted flanged joints in German nuclear power plants. The gasket characteristics required for these calculation methods are based on DIN 28090-1[4], they can be determined experimentally. In Europe, the calculation code EN 1591-1 [5] and the gasket characteristics according to EN 13555[6] are used for flange calculations. Because these calculation algorithms provide not only a stress analysis but also a tightness proof, it would be preferable to use them also in the NPP’s in Switzerland. Additionally, for regulatory approval also the requirements of the ASME BPVC must be fullfilled. For determining the bolting up torque moment of flanges several tables for different nominal diameters of flanges using different gaskets and different combinations of bolt and flange material were established. As leading criteria for an allowable state, the gasket surface pressure, the allowable elastic stress of the bolts and the strain in the flange should be a good and conservative basis for determining allowable torque moments. The herein established tables show only a small part according to a previous paper [7] where different calculation methods for determining bolting up moments were compared to each other. In this paper the bolting-up torque moments determined with the European standard EN 1591-1 for the flange, are assessed on the strain-based acceptance criteria in ASME BPVC, Section III, Appendices EE and FF. The assessment of the torque moment of the bolts remains elastically which should lead to a more conservative insight of the behavior of the flanges.

Young Athletes Upper Knee Muscular Strength Isokinetic Testing / Izokinetičko testiranje snage natkolene muskulature mladih sportista

This research main goal is to determine differences in maximum upper knee musculature torque moment of judo, football and handball players. For the needs of the research, 30 respondents were tested, of which 10 were football, 10 handball players and 10 judo athletes. Testing was conducted in Isokinetic Diagnostic Cabinet of the Provincial Institute for Sports and Sports Medicine in Novi Sad on the isokinetic dynamometer “Easytech prima DOC”. Significant differences were noted in the maximum torque moment of both legs extensors force (PTQR, PTQL) between judo athletes and football players, in favor of judo. Obtained results between observed groups can be attributed to the various sports branches training processes specificities, i.e. performing certain techniques in the sport itself

Pengaruh Jumlah Sudu Terhadap Kinerja Turbin Savonius

Savonius wind turbines are wind turbines that canoperate at low wind speeds, this type of turbine is very suitable tobe used in several places in Indonesia. The research aims toimprove the performance of the Savonius wind turbine withvariations in the number of turbine blades as well as variations inthe velocity of wind speed. The research method wasexperimental where wind turbine testing was carried out withvariations in the number of turbine blades with number of 2, 3and 4 blades, other variations carried out were wind speed at 3.5;4,5; 5.5 and 6.5 m/s. The study results show that the 2-bladeturbine produces greater rotation, but the torque moment islower than the 3 and 4 blade turbines, this can be seen in the lowefficiency of the 2 blade turbine at low wind speeds with highloading. At 3.5 m / s wind turbines 2 blade turbines haveefficiency that tends to be the same as 3 and 4 blade turbines upto 0.5 N but at loads of 0.6 - 1.2 N 2 blade turbines have lowerefficiency, while at wind speeds of 4.5 - 6.5 m / s 2 blade turbineshave greater efficiency than turbines 3 and 4 blades up to a loadof 1.2 N but if the load is added then the efficiency of 2-bladeturbines can be smaller than efficiency 3 and 4-blade.