Article
Optics
Jingyi Li, Wei Zhang, Ye Li, Guangyong Jin
Summary: The propagating evolution of shock waves induced by a nanosecond pulse laser (ns laser) irradiating silicon assisted by a millisecond pulse laser (ms laser) was experimentally investigated. A numerical model was established to obtain the spatial distribution of shock wave velocity. Two types of shock wave acceleration phenomenon were found, and the mechanism was discussed. The results showed that the initial stage of ms laser-induced plasma can provide the initial ions to increase probability of collision ionization between free electrons and vapor atoms, thus accelerating the velocity of the ns laser-induced shock wave. Furthermore, the ms laser-induced plasma as the propagation medium can also accelerate the ns laser-induced shock wave. The shock wave acceleration methods obtained in this paper can promote the development of laser propulsion technology.
Article
Engineering, Multidisciplinary
Wensheng Wei, Yueda Mo, Shouhao Yu, Xiaoling Yang, Wenxi Huang, Senrong Dai
Summary: A CPU-based instrument was designed for measuring the reverse recovery time and charge of low power switching diodes, utilizing ECL circuit for shaping reverse voltage pulse, achieving high-speed signal processing. The application of ECL provided an effective means for signal processing and the design was successfully validated.
Article
Astronomy & Astrophysics
Eoin P. Carley, Baptiste Cecconi, Hamish A. Reid, Carine Briand, K. Sasikumar Raja, Sophie Masson, Vladimir Dorovskyy, Caterina Tiburzi, Nicole Vilmer, Pietro Zucca, Philippe Zarka, Michel Tagger, Jean-Mathias Griessmeier, Stephane Corbel, Gilles Theureau, Alan Loh, Julien N. Girard
Summary: The study observed a type II radio burst and found that the fine structure is related to power-law distribution of density perturbations, closely matching the expected value for fully developed turbulence. The turbulent density inhomogeneities upstream of the shock show the possibility of fine structure and fragmentation occurring due to shock propagation through turbulent coronal plasma.
ASTROPHYSICAL JOURNAL
(2021)
Article
Engineering, Electrical & Electronic
Gabriel Fellner, Lucas Speckbacher, Seyed Mostafa Mousavi, David Johannes Pommerenke, Satyajeet Shinde, Michael Hillstrom, Ram Chundru, Cheung-Wei Lam
Summary: This article presents a novel peak detect and hold (PDH) circuit for the measurement of the peak voltage of electromagnetic-field probes. The circuit combines small size, low power consumption, and nanosecond operation using a discrete bipolar transistor structure with operational transconductance amplifier (OTA) and common-base storage capacitor charge control. The circuit performance is demonstrated for different bias point settings, showing unmatched speed and power consumption compared to the literature. The PDH circuit can be adjusted to the sensor's frequency response using bias settings to minimize power consumption in a multichannel system.
IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT
(2023)
Article
Astronomy & Astrophysics
Noemie Globus, Anatoli Fedynitch, Roger D. Blandford
Summary: The origin of ultra-high-energy cosmic rays is a 60 yr old mystery. With more events at the highest energies, we can limit the sources and study the intervening magnetic fields. A composition-dependent observatory can help distinguish between steady and transient or highly variable sources and provide insight into source models. Prediction of Extreme Energy Cosmic Rays doublets can be used to identify promising detection directions.
ASTROPHYSICAL JOURNAL
(2023)
Article
Biochemistry & Molecular Biology
Yan Mi, Jin Xu, Quan Liu, Xiao Wu, Qian Zhang, Junying Tang
Summary: The study improved the original electroporation mathematical model and proposed a new one considering IRE effect. By simulating the dynamic processes of cells under high-frequency nanosecond pulse bursts, the research revealed the impact of multipulse bursts and intraburst frequency on cell electroporation characteristics.
BIOELECTROCHEMISTRY
(2021)
Article
Physics, Fluids & Plasmas
Jintao Qiu, Cheng Zhang, Zehui Liu, Bangdou Huang, Tao Shao
Summary: The experimental investigation on the runaway electron spectrum showed that at atmospheric pressure and with gap spacing of 5 mm, applied voltages of 70-130 kV, the number of runaway electrons can reach the level of billions. The rough surface cathode creates a more inhomogeneous electric field and larger emission site for the runaway electrons around the cathode.
PLASMA SCIENCE & TECHNOLOGY
(2021)
Article
Astronomy & Astrophysics
Rostom Mbarek, Damiano Caprioli, Kohta Murase
Summary: We calculate the flux of ultrahigh-energy cosmic rays (UHECRs) and high-energy neutrinos produced by active galactic nuclei (AGNs) using 3D relativistic magnetohydrodynamic jet simulations. We find that UHECRs in AGN jets are not significantly affected by photodisintegration, consistent with observations favoring a heavy composition at the highest energies. We also estimate the flux of high-energy neutrinos from AGN jets and find that these neutrinos may account for a sizable fraction of the expected flux, but cannot fully explain the observed flux. Our results suggest that nearby radio galaxies may be more promising as potential sources of UHECRs and neutrinos.
ASTROPHYSICAL JOURNAL
(2023)
Article
Energy & Fuels
Shuangrui Jia, Yunfei Jia, Zewei Bu, Simeng Li, Liang Lv, Shengchang Ji
Summary: The detection of partial discharge (PD) in transformers is important for preventing insulation defects from becoming insulation failures. Optical detection method has strong anti-electromagnetic interference ability and unique advantages. In this study, an optical signal measuring device was designed to detect partial discharge inside the transformer and the characteristics of the optical signal were obtained.
Article
Instruments & Instrumentation
Wojciech Skrzeczanowski, Marek Skorczakowski, Waldemar Zendzian
Summary: The paper describes the results of single and double-pulse LIBS measurements in collinear geometry using a self-made Nd:YAG laser. The laser allows for easy mode change, energy ratio adjustment, and delay time variation between pulses. Strong self-absorption and signal enhancement were observed in the double-pulse mode, confirmed by statistical factorial analysis of LIBS spectra.
METROLOGY AND MEASUREMENT SYSTEMS
(2023)
Article
Engineering, Multidisciplinary
Sharifi A. M. Mohammad Saleh, Afarideh Hossein, Ghergherehchi Mitra, Ahmady Hesam, Simiari Mehdi
Summary: Nuclear Quadrupole Resonance (NQR) is commonly used for detecting Nitrogen-containing materials. An adaptive noise canceling method was employed to improve the signal to noise and interference ratio (SNIR) in FID signals. The proposed system effectively reduced noise and interference and amplified the FID signal.
Article
Astronomy & Astrophysics
Shin-nosuke Ishikawa, Hideaki Matsumura, Yasunobu Uchiyama, Lindsay Glesener
Summary: A concept for machine-learning classification of hard X-ray emissions from solar flares observed by RHESSI is presented, demonstrating a classification accuracy better than 90% using deep-learning techniques. The model can detect occulted flares without the need for image reconstruction nor for visual inspection by experts, showing potential for event screening or event alert for occulted flares.
Article
Instruments & Instrumentation
Toshiyuki Yuhara, Tomokazu Numano
Summary: An additive image can be created from two different dose DR images, allowing estimation of the image noise of the unacquired dose and adjusting it to match the image taken at the actual dose.
JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY
(2021)
Article
Astronomy & Astrophysics
Andrea Caputo, Hongwan Liu, Siddharth Mishra-Sharma, Maxim Pospelov, Joshua T. Ruderman
Summary: In this paper, a new class of dark sector models is proposed, where dark photons oscillate into ordinary photons that contribute to the radio background, explaining both its magnitude and spectral index. These models predict new relativistic degrees of freedom and spectral distortions of the cosmic microwave background, which could be detected in the next generation of experiments.
Article
Engineering, Electrical & Electronic
Dongmei Li, Zhiyuan Xu, Lei Gu, Lanxiang Zhu
Summary: The research focused on adjusting the signal square spectrum bandwidth ratio to solve the problem of identifying radar intra-pulse modulation types. The experimental results demonstrated that the CEEMD method has better decomposition performance.
EURASIP JOURNAL ON ADVANCES IN SIGNAL PROCESSING
(2021)