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Here, we report measurements made with an external vibration-insensitive single-shot interferometer, which is applicable for on-machine measurement. Previously, we developed a simple single-shot interferometry method in which the optical intensities of interference fringes appear not as sinusoidal distributions but have a sawtooth-like distribution, and the peak distortion direction depicts the slope of the measured surfaces. These properties allow use of this method in vibration-insensitive interferometry. In this study, we have experimentally confirmed this concept through measurement of a quarter of a Si wafer specimen 50 mm in diameter. The vibration source was a motorized linear stage the surface of which fluctuated between ±400 nm in height. The obtained surface profiles of the Si wafer were consistent with measurements made with a commercial interferometer within 30 nm. • A novel vibration-resistant optical interferometry method was achieved. • Metal was deposited on one surface of a glass reference plate. • Optical intensity of interference fringe has a sawtooth-like distribution. • A single interferogram is sufficient for determination of surface inclination. • Measured profiles were coincident with target values within 30 nm. [ABSTRACT FROM AUTHOR]

• A newly developed runaway detection system on HL-2M tokamak withn time-resolution of 10 µs. • This diagnostic system is based on the Cherenkov effect, and Al 2 O 3 is chose as the radiator. • The clear experimental evidences of enhanced losses of REs during sawtooth instabilities have been obtained by means of the Cherenkov probe system. An energetic particle diagnostic system based on the Cherenkov effect has been developed to detect the characteristics of runaway electrons (REs) in the HL-2M tokamak. The Cherenkov radiator is a cylinder made of sapphire with a diameter of 5 mm and a height of 10 mm. Its surface is coated with molybdenum film with thickness of 5 µm. The Cherenkov light spectrum which is emitted by REs when they pass through radiator with different energy is simulated by Geant4. Simulation results show that REs with energy above 120 keV can be effectively measured. The A l 2 O 3 radiator is mounted at the end of an adjustable long shaft. The shaft can enter or withdraw from the chamber to optimize the radial position of the radiator. The Cherenkov signal can be transmitted through an optical path to the Silicon Photomultiplier (SiPM) and the sampling frequency of the signal acquisition system is 100 kHz. This probe was installed on the HL-2M device in 2022 and successfully obtained valid data during the autumn experiments. Measurements of the RE losses by the Cherenkov probe have been performed during HL-2M Ohmic discharges. Clear experimental evidences of the enhancement of RE losses during sawtooth instabilities have been obtained by the Cherenkov probe system. A detailed description of the probe system and the first experimental results are reported. [ABSTRACT FROM AUTHOR]

The microstructure and mechanical properties of Sn-0.7Cu solder alloy and Sn-0.7Cu with 1.0–5.0 wt% indium addition were investigated in this study. With indium added into Sn-0.7Cu solder, the melting temperature decreased and the reaction temperature increased. Coarse grains of Cu 6 (Sn,In) 5 intermetallic compounds (IMCs) were formed in the alloy matrix when the indium content increased to 1.0 wt%. Indium was evenly distributed in the β-Sn phase and Cu 6 (Sn,In) 5 IMCs in as-prepared In-containing solder alloys. After isothermal aging, indium accumulated gradually in the Cu 6 (Sn,In) 5 IMCs while decreasing its content in the β-Sn phase. Tensile test results indicated that the ultimate tensile strength increased obviously and that the elongation decreased significantly with indium addition. Sawtooths were observed in the stress-strain curves of all aged In-containing alloys. A model describing a coherent relationship between the β-Sn phase and the Cu 6 (Sn,In) 5 phase was proposed to explain this phenomenon. The fracture surface of the Sn-0.7Cu alloy exhibited a ductile fracture mode while a mixed ductile-brittle fracture mode occurred when excessive indium was added into Sn-0.7Cu alloys. [ABSTRACT FROM AUTHOR]

A laser microscope with a wide field of view developed in our previous study allowed us to observe the whole surface of a cylinder in a very short time. In that study, resolution of the laser microscope in the depth direction was sacrificed to obtain a wide field of view. To overcome this shortcoming and achieve nano-level measurement of 3-dimensional profiles of various objects, we have introduced two-beam interferometry to the wide field of view laser microscope. To achieve a high contrast interference fringe pattern, a glass reference plate was coated with a thin Cr film or other pure metals. The interference fringe pattern was distorted from sinusoidal wave into a sawtooth-like waveform. The distortion of the interference fringe pattern appeared to correspond to the inclination of the specimen surface measured. This shows the possibility of realizing a novel single shot interferometry method capable of determining the surface profile from only one image of the interference fringe pattern without using the phase shift method. The type of distortion of intensity distribution was different for each metal. The mechanisms by which the intensity distribution of the interference fringes changed to sawtooth pattern are discussed from both a Fourier-transform analysis and an electromagnetic approach. [ABSTRACT FROM AUTHOR]

Installing cycling infrastructure well-separated from motorized traffic is hypothesized to increase children's transportation cycling. However, in some streets it may not be possible to install such cycling paths (e.g. due to financial or space constraints). The current paper investigates which physical factors could increase parents' perceptions of environmental supportiveness for children's transportation cycling, across six different types of cycling infrastructure. Parents completed a choice-based conjoint task by indicating which photographed street they preferred to let their child cycle along. The streets were experimentally manipulated on 7 physical factors (e.g. traffic speed, vegetation). Interactions between type of cycle path and the other environmental factors were identified. When no or limited separation from motorized traffic is present, street characteristics increasing parents' safety perceptions (traffic density and speed) should be prioritized when aiming to improve the supportiveness of streets for children's transportation cycling. Comfort and aesthetics can further improve streets' environmental supportiveness when cycling paths are more separated from traffic. [ABSTRACT FROM AUTHOR]

A new fast infrared camera was purchased on the COMPASS tokamak recently. It is equipped with a medium wavelength infrared (3–5 mm) InSb detector and is capable of reaching framerate up to 1.9 kHz in full frame acquisition mode (320 × 256 px.) and up to 90 kHz in sub-windowed mode (64 × 4 px.). First experimental measurements of plasma heat flux to inner and outer wall limiters of the COMPASS tokamak using the new camera are presented. Time evolution of parallel heat flux during sawtooth instability is studied showing strong modulation of the heat flux absolute value whilst keeping constant its radial decay length. Fast modulation of outboard midplane limiter heat loading due to runaway electrons is also presented. The camera will be part of a new fast divertor thermographic system with exceptional spatial resolution (∼0.6–1.3 mm/px. on the target plane, 0.04–0.14 mm/px. mapped to the outer midplane) with a possibility of measurements of radial profiles on the divertor with 320 × 4 px. with temporal resolution better than 20 μs. A design of the foreseen optical divertor system is described together with a design of a special divertor graphite tile used for the IR thermography, that will allow in-situ surface emissivity calibration. [ABSTRACT FROM AUTHOR]

The aim of this paper is to analyze the main features of weakly non-linear waves propagating in a compressible, inviscid, non-ideal gas with infinite electrical conductivity modelled by van der Waals equation of state permeated by transverse magnetic field. An asymptotic approach is used to derive the evolution equation, which characterizes the wave phenomena in a high frequency domain. The growth equation of an acceleration wave is derived as a special case. Further, we also discuss the propagation of disturbances in the form of sawtooth profile. The effect of magnetic field and van der Waals parameter on the decay of sawtooth profile is presented. A remarkable difference between planar and nonplanar flows in magnetic case and nonmagnetic case has been drawn. Also the variation in velocity profile between planar and nonplanar flows has been discussed. [ABSTRACT FROM AUTHOR]

The increased density of the urban population and frequent transportation movement has lead to parking issues in these areas. Many efforts have been made to efficiently utilize the existing parking facilities. Most of these solutions target the large-scale private and public parking facilities; however, the individual parking facilities are not much explored and exploited for reducing the parking issues. In the last few years, the Online-to-Offline (O2O) model has witnessed huge attention from the research community due to its versatile applications in many domains. The main objective of the O2O model is to create service awareness online, allowing potential users to review different offers and then visit local physical places for purchasing. The security of the users' data has always been considered a crucial factor in any public sharing platform. The blockchain model has been regarded as a solid security platform for many public sharing platforms. This work designed a blockchain framework with a novel data verification and role-based Access control method for securing the parking service data. Several experiments are performed using the sawtooth blockchain tool to investigate the performance of the proposed blockchain framework against the baseline approach concerning latency, meantime testing (MTT), throughput, transaction sending rate (TPS), and average response time (ART). The obtained results confirm that the proposed approach is scalable and feasible for smart parking and other IoT-based applications. • To the best of our knowledge, this is our novel contribution to develop an O2O based parking sharing service. • This work designed a blockchain framework with a novel data verification and role-based Access control method for securing the parking service data. • The implementation is done using the Sawtooth blockchain and then performance evaluation using the hyper-ledger caliper tool. • The experimental evaluation confirms that the proposed approach is scalable and is feasible for smart parking and other IoT-based applications. [ABSTRACT FROM AUTHOR]

In the present paper, an asymptotic approach is used to analyse the main features of weakly nonlinear waves propagating in a compressible, inviscid, nonideal gas in the presence of magnetic field. An evolution equation, which characterizes the wave process in the high frequency domain and points out the possibility of wave breaking at a finite time, is derived. The growth equation governing the behaviour of an acceleration wave is recovered as a special case. Further, we consider a sufficiently weak shock at the outset and study the propagation of the disturbance given in the form of a sawtooth profile. It is observed that the non-idealness of the gas causes an early decay of the sawtooth wave as compared to ideal case however the presence of magnetic field causes to slow down the decay process as compared to non-ideal non-magnetic case. A remarkable difference in wave profiles for planar and cylindrically symmetric flows has been observed. The effect of non-idealness, in the presence of magnetic field, on the formation of shock is more dominant in case of cylindrical symmetry as compared to planar case. [ABSTRACT FROM AUTHOR]

Highlights: [•] A X-mode W-band reflectometer is designed and installed on Experimental Advanced Superconducting Tokamak (EAST) for the first time. [•] Both density profile and fluctuations can be measured by the newly developed reflectometer. [•] The core density profile has been measured in high magnetic field condition together with V-band reflectometer. [•] Sawtooth precursor has been measured by fluctuation reflectometer in the low magnetic field condition. [Copyright &y& Elsevier]

Abstract: In accordance with the problems in test for scale factor of resonant micro optical gyro (RMOG) by turntable, a new method based on equivalent input is proposed, and this is by adding sawtooth waveform to the RMOG's phase modulator, the scale factor experimental setup is constructed, the closed-loop transfer functions under turntable input and equivalent input are analyzed, relationship between parameters of the sawtooth waveform and equivalent input is derived, the scale factor and nonlinearity are obtained by the scale factor experimental setup, the scale factor is basically identical to the test result on the turntable, but the nonlinearity also to raise from 0.98% to 0.53%, the results of test demostrate that the method can not only accurately measure the scale factor, but also effectively eliminate the measurement errors due to the vibration and imperfect precision of the turntable. [Copyright &y& Elsevier]

Abstract: The high performance mode (H-mode) is one of the baseline plasma scenarios for the experimental fusion reactor ITER. This scenario features a periodic crash-like reorganization of the plasma pressure and the magnetic flux in the plasma core and plasma periphery. The core instability is often referred to as the sawtooth instability while the instability at the edge of the plasma is referred to as ELM. In this paper we present an algorithm for optimized (low latency, robust and high fidelity) real-time sensing of the crashes. The algorithm is based on time-scale wavelet theory and edge-detection. It is argued that detection of crashes has considerably less delay than the other methods. The realized accuracy of the detection algorithm is well below the uncertainty of the crash period for most crashes. Multiresolution analysis enables distinction between different sizes of sawtooth crashes due to the different sizes of wavelets (scales), resulting in an algorithm, which is robust and accurate. Although strictly speaking, the crash detection method is demonstrated for sawteeth measured with ECE only, it can be applied to any periodic crash, measured with any temporally resolved data. Note that the possibility of differentiating between crash like events of different nature depends on their individual time-scales and used measurement setup. [Copyright &y& Elsevier]

Abstract: Three elderly patients with a clinical diagnosis of posterior crocodile shagreen of the cornea underwent penetrating keratoplasty. Each of the patients had the characteristic symmetrical, polygonal opacities with indistinct edges and intervening clear spaces in the central posterior corneal stroma. Electron microscopic examination of the keratoplasty specimens disclosed the presence of vacuoles throughout the corneal stroma, many of which contained electron-dense material. The vacuoles were observed with increasing density posteriorly and were most concentrated adjacent to the anterior banded portion of Descemet''s membrane. A sawtooth-like configuration of the stromal collagenous lamellae was noted in the posterior cornea in one case. We reviewed the three cases of central corneal clouding reported with histopathological findings as well as the clinical descriptions of this entity. Although a sawtooth-like lamellar configuration of the stromal collagen may be seen by electron microscopy, characteristic vacuoles appear to be the only consistent finding. We believe that posterior crocodile shagreen is most likely a degenerative disorder and that it should be distinguished from central cloudy dystrophy of François by its non-familial pattern of occurrence. [Copyright &y& Elsevier]

Abstract: A soft X-ray (SXR) imaging system composed of three miniature SXR pinhole array camera designed and installed on the joint texas experimental tokamak (J-TEXT) for the study of plasma equilibrium and fluctuation properties during ohmic discharges. The imaging system functions well, giving good resolution and maneuverability. Combined with the use of the biorthogonal decomposition technique, it helps us to analyze the sawtooth crashes and their basic parameters such as reversal surface and modes. Furthermore, the plasma displacement is measured using SXR emission and the results are compared with those from magnetic diagnostic tools. The comparisons verify that the SXR imaging system is a legitimate alternative for non-magnetic plasma offset observation. In addition, it can form the basis of a real-time feedback control system for magnetic-confined plasma. [Copyright &y& Elsevier]

Abstract: Sawtooth oscillations with post-cursor were observed in LHCD plasma on HT-7 tokamak. The mode exists and decays gradually after the crash, which implies that the magnetic reconnection is incomplete and the central safety factor remains below unity after the crash. From results of the singular value decomposition (SVD) and tomographic reconstructions describing the magnetic surface structures in the crash, it was found that the mode survives in the crash. It is shown that, the appearance of the preservation of this mode is inconsistent with the secondary reconnection theory, and we conjecture that the evolving of this mode may be understood with the stochastic field model. [Copyright &y& Elsevier]

TRIUMF's ARIEL pre-buncher is powered by a sawtooth waveform which is the combination of 11.79 MHz, 23.57 MHz and 35.36 MHz harmonics. To upgrade the existing analog and digital hybrid LLRF control system, reduce the hardware cost, and achieve more flexible control of the system, an FPGA based digital daughter board is designed. The generation, control, and regulation of these three harmonics are all incorporated digitally inside a single FPGA. To reduce the number of RF interfaces on the motherboard, the new daughter board is designed to control the amplitude and phase of the sawtooth waveform with one channel ADC and DAC. To lock the output phase of the sawtooth waveform to the reference signal, a digital phase-locked loop is designed to lock all three harmonics to the external reference signal. The related work, including the system design of the LLRF control system and the development of the digital phase-locked loop, are presented in this paper. [ABSTRACT FROM AUTHOR]

• The causal link between the sawtooth-induced heat pulses at the plasma edge and a spontaneous L-H transition is proposed. • The edge turbulence level increases significantly when the sawtooth-induced heat pulse arriving at the plasma edge. • First time to see that the turbulent decorrelation rate increases significantly just before the L-H transition by experiment. • Both turbulent decorrelation rate and nonlinear energy transfer rate play key roles on the turbulence quench. H-modes induced by sawtooth events can be often observed in discharges with marginal auxiliary power injection in EAST. Poloidal flow shear at the very plasma edge, increasing ∼25% up to the threshold value, is observed just before the L-H transition by means of a fast reciprocating probe array in EAST. This suddenly risen poloidal flow shear, caused by the increased turbulent driven Reynolds force, is motived by the heat pulse originally released by a sawtooth crash at the plasma core. Associated with the critical poloidal flow shear, the local turbulent decorrelation rate increases significantly. The increased turbulent decorrelation rate compensated by nonlinear energy transfer rate from the turbulence to the low-frequency shear flows, exceeding the turbulence energy input rate, is sustained for several hundred microseconds till the turbulence quench happening. [ABSTRACT FROM AUTHOR]