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Hviid Mead posted an update 1 week ago
A unified approach to achieve a start-to-end ion optics simulation of an ion beam apparatus coupled to an electrospray ionization source is presented. GSK3326595 research buy We demonstrate that simulations enable reliable information on the behavior and operation of the apparatus to be obtained, but due to the collisions with the buffer gas in the initial stages of the setup, the results concerning the kinetic energy of the ion beam must be treated with care.In order to supplement manufacturers’ information, this department will welcome the submission by our readers of brief communications reporting measurements on the physical properties of materials which supersede earlier data or suggest new research applications.A module of a wireless high voltage generator was tested immersed in both gaseous and liquid environments providing electrical insulation. The overall performance of the module as well as a detailed performance of the key components are reported, and a comparison between the results in gas and liquid is given. The tests performed on the liquid dielectric show that it is a valid alternative to high pressure gas electrical insulation.Nanosecond pulsed liquid discharge has attracted significant attention in various applications, in which adjustable parameters and compact volume of nanosecond pulsed power are essential for the convenience of researchers. In this paper, a compact volume (0.6 × 0.8 × 0.4 m3) nanosecond pulsed power supply is built for the liquid discharge with the capacity charging power supply technology. Moreover, a high-frequency induction feed control system is adopted to achieve synchronizations between insulated gate bipolar transistors to realize the adjustable pulse width and frequency. A non-inductive resistor is used to test the properties of the nanosecond pulse power supply, and results show that the rising time of nanosecond pulse power is 100 ns with the pulse width in the range of 4 µs to ∼100 µs, and the output pulse voltage and repetition frequency are 0 kV-20 kV and 1 Hz-300 Hz, respectively. Moreover, the needle-to-needle electrode discharge in the liquid phase is successfully excited by this power supply with different working conditions.This paper describes a new method of frequency measurement based on lock-in amplifiers (LIAs). In contrast to other frequency measurement methods, such as fast Fourier transformation (FFT), zero crossing, and scanning autocorrelation, this method is based on an adaptable LIA design for high-precision determination of not only the frequency but also the amplitude and phase of periodic signals, even when they are buried in heavy noise with low signal-to-noise ratios. Mathematical derivation of the local spectrum around the center frequency is performed, and the local frequency spectrum waveform of the sinusoidal signal, regardless of whether it is pure or noisy, is found to be exactly of a bell shape that can be described by a three-parameter sine function. Based on the principle of LIAs, the correct frequency can produce a peak amplitude in the local spectrum. As a result, the amplitudes of three frequency points around the target frequency can be used to precisely determine the peak frequency via sinusoidal fitting. The efficiency of the proposed method is log2(N) times that of FFT. Simulation results show that the new algorithm can reach the theoretical Cramer-Rao lower bound and remain below a lock-in upper bound. The new frequency measurement method has been implemented in an field-programmable gate array (FPGA)-based device and systematically tested for its dependence on the frequency, amplitude, and signal-to-noise ratio with typical noise types. Theoretical and experimental results show that the new method can be used in fine determination of the frequency if the user has prior knowledge of the approximate location of the frequency.The potential of optical spectroscopic techniques such as diffused reflectance and fluorescence as non-invasive, in vivo diagnostic tools is being explored and validated recently. In this paper, we present the design and development of a handheld, portable, multimodal fiber optic based probe scheme to sequentially measure diffuse reflectance and fluorescence. The proposed prototype is designed to sequentially acquire diffused reflectance in the broad wavelength range of 400 nm-1600 nm and fluorescence using custom-chosen spectrophotometers, monochromatic and broadband light sources, fibers to accommodate a wide wavelength range, custom-built probe distal end, and a real-time spectral stitching and display unit. The prototype is characterized using in-house fabricated phantom tissue samples with tunable optical properties such as scattering and absorption. The depth profile study is carried out using phantom tissue layers of known optical parameters followed by the sequential measurement of diffused reflectance and fluorescence from the tissue mimicking sample.The distinctive features of a well-known NaI(Tl) scintillation detector, by virtue of its crystal size, are experimentally investigated by observing changes in parameters such as intrinsic efficiency (εi), photo-peak efficiency (εp), resolution, and response function to incident gamma photon energy. This study provides a better understanding for the choice of crystal size of the scintillation detector in Compton scattering experiments. The response function of the NaI(Tl) detector is in the form of an inverse matrix focusing on the retort of the crystal when gamma photons are incident upon it. The response function of the NaI(Tl) detector depends upon the distance between the source and the detector, composition of the material for the crystal itself, photo-fraction, solid angle, incident gamma energy, and geometry of the experimental setup. The factors responsible for broadening of full energy and backscattered peaks are discussed for present investigations. The observed results indicate that the resolution of the detector varies with the incident energy of gamma radiation, and it also depends upon the size of the crystal of the detector. Statistical fluctuations related with the scintillation mechanism are found to be responsible for broadening of instrumental line width (photo-peak). The signal-to-noise ratio and photo-fraction for different crystal sizes of the scintillation detector corrected for efficiency of the detector are also discussed.