Acceleration Environment Research Articles

RETRACTED: A novel hybrid optimized and adaptive reconfigurable framework for the implementation of hybrid bio-inspired classifiers for diagnosis

Abstract Due to recent advances in IoT (Internet of Things) technologies, availability of reliable data and emergence of machine learning, bio-inspired learning and artificial intelligence, has demonstrated its ability to solve the large complex problems which is not possible before. In particular, machine learning and bio-inspired learning algorithms provides the effective solutions in image processing techniques. However, the implementation of the above-mentioned algorithms in the general CPU requires the intensive usage of bandwidth, area and power which makes the CPU unhealthy of usage and implementation. To overcome this problem, ASIC (application specific integrated circuits), GPU (Graphics Processing Unit) &FPGA (Field Programmable gate arrays) have been employed to improve the performance of the hybrid machine learning (ML) classifiers and deep learning algorithms. FPGA has been recently employed for an effective implementation and to achieve the high performance of the learning algorithms. But integrating the complex learning algorithms in FPGA still remains to be real challenge among the researchers. The paper proposes new reconfigurable architectures for bio- inspired classifiers to diagnosis the medical casualties which can be suitable for the tele health care applications. This paper aim is as follows (i) Design and implementation of Parallel Fusion of FSM and Reconfigurable shared Distributed Arithmetic for Bio-Inspired Classifiers (ii) Development of Accelerator Environment to test the performance of proposed architecture (iii) Performance evaluation of proposed architecture in terms of accuracy of detection in compared with MATLAB simulation iv) Implementation of proposed architectures in different ARtix-7 architectures and determination of power, throughput and area . Moreover, the proposed architecture has been tested with the and compared with the other existing architectures.

Modal instability suppression in a high-average-power and high-finesse Fabry-Perot cavity.

An experimental method to remove modal instabilities induced by thermoelastic deformation in optical high-finesse resonators is presented and experimentally investigated in this paper. The method is found suitable for multi-mirror folded monolithic and compact cavities, such as those used in the particle accelerator environment. It is also suitable for very high stacked average power. Here we demonstrate stable operation at the 200 kW intracavity average power.

Performance optimization of capacitive motion sensing (CMS) system for intra-fraction motion detection during stereotactic radiosurgery

The purpose of this investigation is to improve intra-fractional motion detection during cranial stereotactic radiosurgery with a novel capacitive motion sensing (CMS) system. Previous work showed that a capacitive detection system, based on a MPR121 capacitance-to-digital converter, provided a number of advantages over existing patient imaging systems used in the clinic, by uniquely offering ionizing-radiation-free and continuous monitoring without modification to the immobilization mask or treatment room. However, in order to provide submillimeter detection accuracy, the MPR121-based CMS system required relatively large sensors in close proximity to the patient. Therefore, the aim of this investigation was to improve sensitivity of the system, allowing reduction in sensor size and preserving its stable operation in the linear accelerator environment. For this, we developed, characterized and compared motion detection capabilities of four CMS systems based on different capacitance-to-digital converters: MPR121, CPT212B, FDC1004 and FDC2214. Among all candidates, the FDC2214-based system was found to uniquely combine accurate 3D motion detection in real time, with stable performance under ionizing radiation. It exhibited an order of magnitude improvement in sensitivity in comparison with the proof-of-study system, allowing a spatial precision as low as 0.3 mm, and its overall performance was found to satisfy the AAPM practice guidelines of positioning tolerance within 1 mm. Furthermore, the high sensitivity of the system allows both reduction of the sensor area and location more distant from the patient surface, which are key improvements with regard to development of a clinical device.

A diagnostic of the orbital spectrum of LS 5039 with Fermi-LAT

LS 5039 is a well-known γ-ray binary system which consists of an unknown compact object and a massive companion O star. It shows rather stable emissions at high energies over years and hence serves as an ideal laboratory to investigate the emission mechanism for such peculiar systems which emit prominent γ-rays. To this end, we take the orbital phase resolved energy spectrum as observed by Fermi-LAT over 10 years. We divide the orbit into four orbital phases, each with an orbital phase range of 0.25, centered at 0.00, 0.25, 0.50 and 0.75 respectively, where the phase 0.0 is the periastron and phase 0.5 is the apastron. The phases around 0.25 and 0.75 are symmetric and hence are supposed to have identical local acceleration environment. The spectral analysis shows that the Fermi-LAT spectra are largely different from these two symmetric orbital phases: the emission from orbital phase 0.25 turns out to be significantly stronger than that from 0.75. This result does not fit a scenario that γ-rays are Doppler boosted emission from bow shock tails if LS 5039 has a shock configuration similar to PSR B1259-63, and indicates that the inverse Compton scatterings between the shock accelerated plasma and the stellar particle environment is the underline procedure. We also find that the previous report for a disappearance of the orbital modulation at 3–20 GeV is due to the similar spectral turn-over energies of the different orbital phases. The spectral properties of periastron and apastron regions are addressed in the context of the measurements in phase regions around 0.25 and 0.75.

Experimental study of consistency degradation of different greases in mixed neutron and gamma radiation

Many of the moving components in accelerator and target environments require lubrication. Lubricants in such environments are exposed to high fluxes of secondary radiation, which originates from beam interactions with the target and from beam losses. The secondary radiation is a mix of components, which can include significant fractions of neutrons. Lubricants are radiation-sensitive polymeric materials. The radiation-induced modifications of their structure reduce their service lifetime and impose additional facility maintenance, which is complicated by the environmental radioactivity. The study of the lubricants radiation resistance is therefore necessary for the construction of new generation accelerators and target systems. Nevertheless, data collected in mixed radiation fields are scarce. Nine commercial greases were irradiated at a TRIGA Mark II Research Reactor to serve for the construction of new accelerator projects like the European Spallation Source (ESS) at Lund (Sweden) and Selective Production of Exotic Species (SPES) at Legnaro, (Italy). Mixed neutron and gamma doses ranging from 0.1 MGy to 9.0 MGy were delivered to the greases. For an experimental quantification of their degradation, consistency was measured. Two of the greases remained stable, while the others became fluid. Post-irradiation examinations evidence the cleavage of the polymeric structure as the dominant radiation effect. Dose and fluence limits for the use of each product are presented. Apart from the scientific significance, the results represent an original and useful reference in selecting radiation resistant greases for accelerator and target applications.

Experimental Study on the Damping Effect of Multi-Unit Particle Dampers Applied to Bracket Structure

Particle damping (PD) is a passive mean of vibration control in which small metallic or ceramic particles are placed inside a cavity that attached to the primary structure at the place of high vibration amplitudes. The kinetic energy of the primary structure is dissipated by non-elastic impact and friction between particles and walls. This paper represents a series of experimental investigations of the effects of multi-unit particle dampers (MUPD) attached to a bracket structure under harmonic excitation and random excitation. As a platform to investigate the particle damping characteristics under extreme acceleration environments, the bracket structure was featured by an extremely high response on the top, and its maximum acceleration exceeds 50 times gravity acceleration when the bracket structure was subjected to resonance. This broad range of acceleration conditions was far beyond the scope concerned in most previous work. The experimental results show that for a small weight penalty (no more than 8.8%), multi-unit particle damper can reduce the resonance of the primary structure by more than 50%, whether under sinusoidal excitation or random excitation. And the response of the primary structure depends on the type of cavities and filled coefficient. Layering the cavity in the direction of the main vibration can improve the damping capacity of the multi-unit particle damper. And the damper with small particle size and large number of features is suitable for vibration reduction under high acceleration conditions.

Cavity Simulator for European Spallation Source

European Spallation Source (ESS) will be the brightest neutron source in the world. It is being built in Lund, Sweden. Over 120 superconducting cavities will be installed in the facility, each regulated by an individual low-level radio frequency (LLRF) control system. To reduce the risk of testing the systems on real cavities, a cavity simulator was designed. It reproduces the behavior of superconducting cavities used in the medium and high beta sections of ESS's Linac. The high power RF amplifier and piezo actuators parameters are also simulated. Based on the RF drive and piezo control signals, the cavity simulator generates the RF signals acquired by the inputs of the LLRF control system. This is used to close the LLRF feedback loop in real time. The RF front end of the cavity simulator consists of vector modulators, down-converting circuits, and a set of fast data converters. The cavity response simulation is performed in a high-speed field programmable gate array logic by a dedicated firmware that was optimized to minimize the processing time. The device also generates clock, local oscillator, and the 704.42-MHz reference signals to allow for system tests outside of the accelerator environment. In this paper, the design of the cavity simulator, description of the algorithms used in the firmware, and measurement results of the device are presented.

Proton-irradiation-immune electronics implemented with two-dimensional charge-density-wave devices.

We demonstrate that charge-density-wave devices with quasi-two-dimensional 1T-TaS2 channels show remarkable immunity to bombardment with 1.8 MeV protons to a fluence of at least 1014 H+cm-2. The current-voltage characteristics of these devices do not change as a result of proton irradiation, in striking contrast to most conventional semiconductor devices or other two-dimensional devices. Only negligible changes are found in the low-frequency noise spectra. The radiation immunity of these "all-metallic" charge-density-wave devices is attributed to the quasi-2D nature of the electron transport in the nanoscale-thickness channel, high concentration of charge carriers in the utilized charge-density-wave phases, and two-dimensional device design. Such devices, capable of operating over a wide temperature range, can constitute a crucial segment of future electronics for space, particle accelerator and other radiation environments.

Model and experiment of scale factor acceleration sensitivity of MEMS gyroscope in high acceleration environment

With the development of MEMS gyroscope, acceleration sensitivity is becoming an important factor in application. The acceleration sensitivity would produce an obvious output error, and researchers mainly focus on bias acceleration sensitivity. Yet, in environment of high acceleration and angular rate, it is the scale factor acceleration sensitivity that influences the output most, and there is little research on it. In this paper, scale factor acceleration sensitivity of MEMS gyroscope in high acceleration environment is investigated with our established theoretical model and experimental measurement. Based on our proposed method of measuring the acceleration sensitivity in environment of high acceleration and angular rate, the MEMS tuning fork gyroscope is used for the measurement. The results show that the output error caused by acceleration can be up to − 30.1°/s and the scale factor acceleration sensitivity contributes the most. The coefficient of scale factor acceleration sensitivity is 35 ppm/g under 50g acceleration, and this coefficient increases linearly with acceleration that coincides with theoretical model. Lastly, some suggestions of decreasing scale factor acceleration sensitivity are given. This work is useful for the researchers to improve the performance of acceleration sensitivity of MEMS gyroscope.

Human perception of whole body roll-tilt orientation in a hypogravity analog: underestimation and adaptation.

Overestimation of roll tilt in hypergravity ("G-excess" illusion) has been demonstrated, but corresponding sustained hypogravic conditions are impossible to create in ground laboratories. In this article we describe the first systematic experimental evidence that in a hypogravity analog, humans underestimate roll tilt. We studied perception of self-roll tilt in nine subjects, who were supine while spun on a centrifuge to create a hypogravity analog. By varying the centrifuge rotation rate, we modulated the centripetal acceleration (GC) at the subject's head location (0.5 or 1 GC) along the body axis. We measured orientation perception using a subjective visual vertical task in which subjects aligned an illuminated bar with their perceived centripetal acceleration direction during tilts (±11.5-28.5°). As hypothesized, based on the reduced utricular otolith shearing, subjects initially underestimated roll tilts in the 0.5 GC condition compared with the 1 GC condition (mean perceptual gain change = -0.27, P = 0.01). When visual feedback was given after each trial in 0.5 GC, subjects' perceptual gain increased in approximately exponential fashion over time (time constant = 16 tilts or 13 min), and after 45 min, the perceptual gain was not significantly different from the 1 GC baseline (mean gain difference between 1 GC initial and 0.5 GC final = 0.16, P = 0.3). Thus humans modified their interpretation of sensory cues to more correctly report orientation during this hypogravity analog. Quantifying the acute orientation perceptual learning in such an altered gravity environment may have implications for human space exploration on the moon or Mars. NEW & NOTEWORTHY Humans systematically overestimate roll tilt in hypergravity. However, human perception of orientation in hypogravity has not been quantified across a range of tilt angles. Using a centrifuge to create a hypogravity centripetal acceleration environment, we found initial underestimation of roll tilt. Providing static visual feedback, perceptual learning reduced underestimation during the hypogravity analog. These altered gravity orientation perceptual errors and adaptation may have implications for astronauts.

Experimental stabilization of transverse collective instabilities in the LHC with second order chromaticity

This paper discusses measurements on the stabilization of single bunches with second order chromaticity (${Q}^{\ensuremath{'}\ensuremath{'}}$) in the Large Hadron Collider (LHC) at CERN. ${Q}^{\ensuremath{'}\ensuremath{'}}$ introduces an incoherent betatron tune spread which can produce Landau damping of transverse instabilities. Although the resulting stabilizing effect is similar to that provided by Landau octupoles, the underlying beam dynamics are different. Since the tune spread from ${Q}^{\ensuremath{'}\ensuremath{'}}$ is based on the longitudinal rather than the transverse action of the particles, it will not be affected by the smaller transverse emittance beams of future machines, such as the High Luminosity LHC or the Future Circular Collider, and may hence provide more efficient Landau damping than magnetic octupoles. This study serves as a proof-of-principle experiment to demonstrate Landau damping from detuning with longitudinal action by means of ${Q}^{\ensuremath{'}\ensuremath{'}}$ in a carefully prepared and well-understood accelerator environment. The agreement between measurements and pyheadtail tracking simulations shows that ${Q}^{\ensuremath{'}\ensuremath{'}}$ indeed contributes to the beam stability, that the numerical model of the LHC is accurate, and that the involved beam dynamics mechanisms are understood from both the single- and multiparticle effects points of view. The results also serve as a first experimental validation of the recently proposed radio frequency quadrupole for Landau damping.

Evolution of Total Ionizing Dose Effects in MOS Devices With Moore’s Law Scaling

The general reduction in the thicknesses of critical dielectric layers driven by Moore’s law scaling has led to increasingly more manageable total-ionizing-dose (TID) response over the last ~50 years. Effects of oxide, interface, and border traps in MOS gate oxides on TID response are now mostly well known for SiO2 gate dielectrics, and the leakage currents due to isolation oxides can be conservatively bounded with existing test methods. Radiation hardened and/or radiation-tolerant technologies have been developed that can survive doses that exceed 1 Mrad(SiO2). Advances in computing technology enabled by Moore’s law scaling and concomitant enhancements in computational techniques have greatly facilitated the modeling and simulation of TID effects in microelectronic devices and ICs. However, the TID response of nanoscale MOS devices with advanced gate stacks and high- ${K}$ gate dielectrics, and/or alternative materials to Si, is often more complex than for MOS devices with SiO2 gate oxides. TID challenges remain for linear bipolar technologies that exhibit enhanced low-dose-rate sensitivity and for microelectronic devices that must function at doses above ~100 Mrad(SiO2), e.g., in high luminosity accelerator environments. TID effects have also recently been observed in wide bandgap semiconductor devices (e.g., GaN/AlGaN HEMTs) with no gate oxide.

Study of the redistribution of solute in eutectic lead-tin alloys solidified under high acceleration

With the objective of studying the effects of gravity in the solidification of materials, a centrifugal that can offer an acceleration environment bigger than gravity during the casting process was developed in the Laboratory of Sensors and Materials of the National Institute for Space Research (LABAS /INPE). So, a lead-tin eutectic alloy was tested and solidified in two different accelerations, 1 g and 9 g (with 1 g equal to 9.8 m/s²). This work presents changes caused by the difference in acceleration in the alloy’s phases distribution along the sample.

A method for radiological characterization based on fluence conversion coefficients

Radiological characterization of components in accelerator environments is often required to ensure adequate radiation protection during maintenance, transport and handling as well as for the selection of the proper disposal pathway. The relevant quantities are typical the weighted sums of specific activities with radionuclide-specific weighting coefficients. Traditional methods based on Monte Carlo simulations are radionuclide creation-event based or the particle fluences in the regions of interest are scored and then off-line weighted with radionuclide production cross sections. The presented method bases the radiological characterization on a set of fluence conversion coefficients. For a given irradiation profile and cool-down time, radionuclide production cross-sections, material composition and radionuclide-specific weighting coefficients, a set of particle type and energy dependent fluence conversion coefficients is computed. These fluence conversion coefficients can then be used in a Monte Carlo transport code to perform on-line weighting to directly obtain the desired radiological characterization, either by using built-in multiplier features such as in the PHITS code or by writing a dedicated user routine such as for the FLUKA code. The presented method has been validated against the standard event-based methods directly available in Monte Carlo transport codes.

The Sun–Earth saddle point: characterization and opportunities to test general relativity

The saddle points are locations where the net gravitational accelerations balance. These regions are gathering more attention within the astrophysics community. Regions about the saddle points present clean, close-to-zero background acceleration environments where possible deviations from General Relativity can be tested and quantified. Their location suggests that flying through a saddle point can be accomplished by leveraging highly nonlinear orbits. In this paper, the geometrical and dynamical properties of the Sun–Earth saddle point are characterized. A systematic approach is devised to find ballistic orbits that experience one or multiple passages through this point. A parametric analysis is performed to consider spacecraft initially on $$L_{1,2}$$ Lagrange point orbits. Sun–Earth saddle point ballistic fly-through trajectories are evaluated and classified for potential use. Results indicate an abundance of short-duration, regular solutions with a variety of characteristics.

Design and Manufacturing of the First Industrial-Grade CLIQ Units for the Protection of Superconducting Magnets for the High-Luminosity LHC Project at CERN

The newly developed concept of coupling-loss-induced quench (CLIQ) used in the domain of superconducting magnets quench protection has opened a new path toward efficient magnet protection. Subsequently to the first trials using ad hoc solutions in order to confirm functionality and performance of the method, two pre-series of three units each with different hardware configurations have been recently manufactured at CERN. Starting from the design phase, the hardware realization follows industrial standards and associated quality control. At the same time, aspects related to the long-term operation of the units have also been addressed. This paper discusses the design and manufacturing issues, the construction details, and the decisions made on choices considering their operation in test stations and in a final accelerator environment. The results of the tests of these units before connecting them to a superconducting magnet will be presented and analyzed.

Coil-free active stabilisation of extended payloads with optical inertial sensors

This paper presents a new active isolation strategy and system which is dedicated to extended payloads, and compatible with the particle accelerator environment. In comparison to the current isolation systems used in this environment, the system proposed does not contain any coil or elastomer, and the supporting frame is dedicated to isolating long payloads from seismic motion. The concept proposed has been tested numerically on 3 and 6 degrees of freedom (DOF) models, and validated experimentally on a 1-DOF scaled test set-up. An attenuation of 40 dB at 1 Hz has been reached with the stage built. The complete description of performance and a noise budgeting are included in this paper.

A Fabry-Pérot interferometer with wire-grid polarizers as beamsplitters at terahertz frequencies.

The design of a compact Fabry-Pérot interferometer (FPi) and results of the experimental studies carried out using the device are presented. Our FPi uses freestanding wire-grid polarizers (WGPs) as beamsplitters and is suitable for use at terahertz (THz) frequencies. The FPi was studied at the LUCX facility, KEK, Japan, and an 8 MeV linear electron accelerator was used to generate coherent Smith-Purcell radiation. The FPi was designed to be easy to align and reposition for experiments at linear accelerator facilities. All of the components used were required to have a flat or well understood frequency response in the THz range. The performance of the FPi with WGPs was compared to that of a Michelson interferometer and the FPi is seen to perform well. The effectiveness of the beamsplitters used in the FPi is also investigated. Measurements made with the FPi using WGPs, the preferred beamsplitters, are compared to measurements made with the FPi using silicon wafers as alternative beamsplitters. The FPi performs well with both types of beamsplitter in the frequency range used (0.3-0.5 THz). The successful measurements taken with the FPi demonstrate a compact and adaptable interferometer that is capable of analyzing THz radiation over a broad frequency range. The scheme is particularly well suited for polarization studies of THz radiation produced in an accelerator environment.

Study of ignition method for firing experiments to visualize boundary layer combustion of paraffin fuel in acceleration environments

Study of ignition method for firing experiments to visualize boundary layer combustion of paraffin fuel in acceleration environments

RLG SINS Dynamic Error Compensation under Vibration Environments

The dither axis bending occurs in the presence of input acceleration acting on the laser block of the ring laser gyro (RLG) due to the limited transverse stiffness of the dither motor, which will cause g-sensitive misalignments under vibration environments. A novel RLG SINS dynamic error compensation method is proposed under vibration environments in this paper. G-sensitive misalignment model of the RLG unit is developed. The equivalent gyro drift model under rotation and acceleration environments is deduced to describe the dynamic error. Optimized vibration experiments are conducted to estimate the unknown parameters. Vibration experiment results prove the validity of this method.