Fatigue Life of Austenitic Steel 304 Bolts Strengthened by Surface Treatment with Graphene Oxide Layer and Surface Shot Peening

This paper presents the results of investigations of the effect of graphene oxide and surface shot peening on the mechanical properties and fatigue life of bolts made of austenitic 304 steel. An innovative method for the uniform deposition of graphene oxide on screws is presented. The process involved activating the surface using plasma and then performing graphene oxide deposition using centrifugal force and vacuum drying. The screw specimens prepared in this way were subjected to a surface peening process. Comparative studies have shown that the combination of graphene oxide deposition and shot peening processes results in an increase in fatigue life of approximately 42 ÷ 275% (depending on the stress amplitude level) compared to the as-delivered samples. The results presented are promising and may provide a basis for further research on the application of graphene and its derivatives to increase fatigue life and improve the mechanical properties of machine components.

NLO EW and QCD corrections to polarized ZZ production in the four-charged-lepton channel at the LHC

Measuring the polarization of electroweak bosons at the LHC allows for important tests of the electroweak-symmetry-breaking mechanism that is realized in nature. Therefore, precise Standard Model predictions are needed for the production of polarized bosons in the presence of realistic kinematic selections. We formulate a method for the calculation of polarized cross-sections at NLO that relies on the pole approximation and the separation of polarized matrix elements at the amplitude level. In this framework, we compute NLO-accurate cross-sections for the production of two polarized Z bosons at the LHC, including for the first time NLO EW corrections and combining them with NLO QCD corrections and contributions from the gluon-induced process.

Проблемы локации источников акустической эмиссии

The accuracy of the location of acoustic emission (AE) sources in the concentrator zones (central holes 5 mm in diameter) located at a distance of 40 mm from the receiving transducers during tensile tests of steel, aluminum alloy and composite flat specimens with dimensions of 550x50x4 mm was evaluated. Calculated speed dependence of propagation of pulses on the level of their amplitude and the partial energy of the high-frequency components of the spectrum is studied. With the threshold method of signal registration, the error in the location of AE event sources arising in the near zone of the receiving transducers at a distance 𝛥L<0.1 m can significantly exceed 10% relative to the base size (B) of the location area, when B<0.5 m. Moreover, with a decrease in the distance 𝛥L<0.05 m, the level of possible error will increase, reaching 20-30% relative to the basic size of the antenna array, when recording pulses with an amplitude level um<60 dB and a fraction of the energy of high-frequency spectrum components not exceeding 10%.

A prescription for projectors to compute helicity amplitudes in D dimensions

This article discusses a prescription to compute polarized dimensionally regularized amplitudes, providing a recipe for constructing simple and general polarized amplitude projectors in D dimensions that avoids conventional Lorentz tensor decomposition and avoids also dimensional splitting. Because of the latter, commutation between Lorentz index contraction and loop integration is preserved within this prescription, which entails certain technical advantages. The usage of these D-dimensional polarized amplitude projectors results in helicity amplitudes that can be expressed solely in terms of external momenta, but different from those defined in the existing dimensional regularization schemes. Furthermore, we argue that despite being different from the conventional dimensional regularization scheme (CDR), owing to the amplitude-level factorization of ultraviolet and infrared singularities, our prescription can be used, within an infrared subtraction framework, in a hybrid way without re-calculating the (process-independent) integrated subtraction coefficients, many of which are available in CDR. This hybrid CDR-compatible prescription is shown to be unitary. We include two examples to demonstrate this explicitly and also to illustrate its usage in practice.

Wide band fiber systems and long transmission applications based on optimum optical fiber amplifiers lengths

Article clarified the optimum fiber amplifiers length for wide band fiber system applications. Optical suppressed carrier transceiver with various fiber amplifier lengths in long haul applications is simulated by using optisystem simulation program version 13. Max. Q coefficient and min. BER can be tested for various fiber amplifiers lengths from 5 to 30 m. The optimum performance efficiency is achieved with 5 m amplifier length which the max. Q coefficient is 62.5 and bits error rate is tended to zero. Peak power amplitude level, noise signal power level, noise signal amplitude level (NSAL) and peak signal amplitude level after channel with a 45 km length for optimum fiber optic amplifier length of 5 m are measured.

Optimization of tocols and γ-oryzanol extraction from rice bran using ultrasound and soybean oil as a green solvent

A new process was developed to extract tocols and γ-oryzanol from rice bran using ultrasound with soybean oil as a natural solvent. Results were compared to the conventional solvent method. The extraction process was optimized using response surface methodology (RSM) with three independent process variables as amplitude level (A) (20-60%), extraction temperature (B) (25-65°C) and time (C) (20-60 mins). Statistical analysis indicated that models developed for all responses were significant. Linear terms of all process variables had significant effects on α-tocopherol, γ-tocopherol, and γoryzanol, while quadratic effects of amplitude level (A2), temperature (B2) and time (C2) on all responses were highly significant. Optimal process conditions for maximum yield of tocopherols and γ-oryzanol were 40% amplitude level, 65°C solution temperature and 40 mins. Yields of α-tocopherol and γ-oryzanol in oil extracted under the optimal conditions or ultrasound-assisted soybean oil extraction (O-UASO) were comparable to oil yield produced by conventional solvent extraction (O-CSE). Interestingly, O-UASO showed higher total antioxidant activities compared with O-CSE. Extraction using ultrasound with soybean oil was proposed as an effective alternative green process to improve oil functionality without the need for separating environmentally hazardous organic solvents.

Four bits data sequence generators based ytterbium doped fiber amplifiers for upgrading maximum Q factor and minimum BER

We have simulated four bits data sequence generators based ytterbium-doped fiber amplifiers for upgrading max. Q factor and min. BER. Optical power variations against time duration after fiber cable length of 250 km with the bits sequence generators of 0101, 1000, and 1010 respectively are simulated. As well as the electrical power/total received power variations against frequency after photodetector receiver with the bits sequence generators of 0101, 1000, and 1010 respectively are discussed in details. Moreover, the signal power amplitude level with the time period duration after photodetector receiver/3R regenerator with the bits sequence generators of 0101, 1000, and 1010 respectively are clarified to show the max. Q factor and min. BER values for each case.

FFBPNN-BASED HIGH DROWSINESS CLASSIFICATION USING EMG AND WPT

The detection of drowsiness level is important because it is the main reason for fatal road accidents. Electromyography of the upper arm and shoulder is an important physiological signal affected by drivers’ drowsiness, in which its amplitude level and frequency band of the sleep-deprived case are different than those of the alert state. Therefore depending on electromyography (EMG), its drowsiness frequency (80–100[Formula: see text]Hz) was detected in order to determine high drowsiness state based on wavelet packet transform (WPT) which decomposes the EMG signal into its approximation and detail coefficients up to level 4 using db2, db7, sym5 and coif5 wavelets. In this research after extraction, the two higher order statistical features, kurtosis and skewness, are computed from 3[Formula: see text]s window of the three EMG channels, and analysis of variance test is used to check whether their mean values are different for the different classes as both [Formula: see text]-values are less than 0.005 under db2 wavelet. Therefore, they were supplied to feed forward back propagation neural network (FFBPNN) as this type of neural network is used for distinguishing and classification purposes for different objects. They obtained an accuracy of 75% for detecting high levels among other levels of normal and low drowsiness with an average sensitivity of 78.63% and specificity of 75.97% because the spectrum of the EMG alert (non-drowsiness) signal of 80–100 Hz is different from that of drowsy 80–90[Formula: see text]Hz and high drowsy 78–95[Formula: see text]Hz signals.

PERAWATAN PREVENTIF MESIN BUBUT MENGGUNAKAN METODE ANALISIS GETARAN DALAM BERBAGAI KONDISI KECEPATAN SPINDLE

This research proposes a new idea of the preventive maintenance method of the lathe by analyzing the vibration on the fixed gear gearbox of the Maximat lathe. From the results of the vibrations that occur, checks are carried out on the lubricating oil, disability of the existing gears and bearings, and then repairing the gear and bearing and replacing the lubricating oil. To find out the magnitude of vibration that occurs in this maximat lathe, rotation variations are carried out by 1000 (rpm), 1500 (rpm) and 2000 (rpm). The highest average amplitude value at 1000 RPM engine speed is on the Bu04 machine with a value of 0.034 mm / s RMS while the lowest value is obtained on the Bu03 lathe with a value of 0.029 mm / s RMS. At 1500 RPM engine speed, the highest average amplitude value is obtained on the Bu03 lathe with a value of 0.045 mm / s RMS. On the Bu02 lathe with a value of 0.032 mm / s RMS. At 2000 RPM engine speed, the highest average value of amplitude was obtained in the Bu03 lathe with a value of 0.069 mm / s RMS. While the lowest value obtained on the Bu02 lathe with a value of 0.050 mm / s RMS. The lower the vibration of the lathe, the more optimal the results of turning. There is an influence between the speed of the engine against the vibrations that occur. Lathe with a high amplitude level indicates that there are components that need attention