Low-frequency noises as a tool for UV detector characterisation

2006 ◽  
Vol 14 (2) ◽  
Author(s):  
R. Ćwirko ◽  
Z. Bielecki ◽  
J. Ćwirko ◽  
L. Dobrzański
Keyword(s):  
Energy Gap ◽  
Supply Voltage ◽  
Low Frequency ◽  
Measuring System ◽  
Semiconductor Detectors ◽  
Uv Detector ◽  
Uv Detectors ◽  
Noise Characteristics ◽  
Wide Range ◽  
Wide Energy

AbstractUltraviolet (UV) semiconductor detectors are mainly made of materials with wide energy gap, i.e., of AlGaN, GaP, SiC, and diamond. The article describes methodology of measurements of characteristics of low-frequency noises of UV detectors and presents the developed measuring system. Basing on analysis of noise characteristics of detectors, an optimal working point of detector can be determined. The results of measurements of noise characteristics of UV detectors made of AlGaN are shown. The measurements have been carried out in wide range of temperatures for several values of a detector supply voltage.

Diagnostic Train for High Speed Line: A Tool for Improving Vehicle and Track Maintenance

2007 ◽  
Author(s):  
Giorgio Diana ◽  
Federico Cheli ◽  
Paolo Belforte ◽  
Ferruccio Resta ◽  
Michele Elia ◽  
...  
Keyword(s):  
High Speed ◽  
Low Frequency ◽  
Measuring System ◽  
Acceleration Measurement ◽  
Railway Network ◽  
Track Geometry ◽  
Track Maintenance ◽  
Wide Range ◽  
Set Up ◽  
Multi Body

During 2005, the Italian railway Network Operator (RFI – Rete Ferroviaria Italiana) realized two ETR500 train sets completely dedicated to diagnostic operation on the new high speed lines being built in Italy. During 2006, these train were equipped with a complete acceleration measuring system for test activities on new Italian high speed line Turin – Novara and Rome – Neaples. A complete accelerometric measurement set up has been installed for track investigation. To this aim, the experimental set up is able to identify vertical profile of track geometry, without the limitation to 25 – 30 m, typical of the traditional measuring methods. On the other hand, a tool for predictive identification of hunting instability has been developed. For each run, it is possible to define a map, highlighting all the irregularity wavelengths involved as a function of the space: for high speed application wavelength over 100 m can become really important both for comfort and safety, because they are able to interest low frequency dynamic (around 0.8 – 1.5 Hz). Moreover, with the aim of identifying the beginning of hunting instability, a tool has been developed in order to identify yaw instability vibration mode and thus its non-dimensional damping, just by bogie yaw acceleration measurement. Both this tools have been developed by means of comparison between numerical multi body simulations and experimental measurements. Numerical simulation have been used to simulate a wide range of operating condition, that was of fundamental importance in tuning of such tools. Full evidence on these method will be given in the paper, together with an example of the obtained results.

scholarly journals Low Noise Programmable DC Amplifier with Remote Control

2019 ◽  
Vol 22 (4) ◽  
pp. 99-108
Author(s):  
Viktor E. Ivanov ◽  
Chye En Un
Keyword(s):  
Flicker Noise ◽  
Experimental Studies ◽  
Low Frequency ◽  
Intrinsic Noise ◽  
Measuring Channel ◽  
Low Noise ◽  
Measuring System ◽  
Frequency Noise ◽  
Measuring Systems ◽  
Wide Range

Introduction. In modern experimental technology, the direction associated with the development of information-measuring systems for recording, pre-processing and analyzing excess low-frequency noise (flicker noise) is well known. Currently, such measuring systems are mainly presented in the form of particular solutions, due to the large variety of research goals and objectives. At the same time, for automation of the experiment, multichannel measuring complexes with the possibility of flexible reconfiguration of the measuring channel according to the task are highly demanded. It is obvious that any distributed measuring channel is represented as a multi-stage scheme with given functions and parameters of each stage, which makes it difficult for the measuring system to adapt to different conditions and tasks of the experiment. The logical solution to this problem is a deep unification of all components of the measuring channel while maintaining good performance characteristics. One of the main problems with this is the evaluation of the intrinsic noise of electronic elements, which provide for changing the parameters of the amplifier.Objective. Experimental analysis of the intrinsic noise of electronic potentiometers, development of the concept and study of parameters of a low-noise DC amplifier with a high degree of unification, the possibility of external electronic control and the use of built-in characteristics correction algorithms.Materials and methods. To achieve the set result, a method for measuring the noise of electronic potentiometers was proposed and experimental studies were carried out.Results. According to the calculation results and experimental studies, it was shown that the specific noise of the electronic potentiometers corresponds to the noise of the metal-film resistors, which makes it possible to use them in low-noise amplification stages. The developed circuit solutions allow the implementation of a unified amplifying module with cascading to build low-noise measuring DC paths based on electronic potentiometers. External and internal digital control allows you to significantly improve the performance of the measuring path as a whole and allows you to adapt it to a wide range of tasks.Conclusion. As part of the study, a method was proposed for measuring the noise of electronic potentiometers, analytical and experimental studies were carried out, and a prototype of a low-noise amplifier was developed and investigated.

scholarly journals Practical application of wavelets in the engine's vibroacoustic analysis

2018 ◽  
Vol 19 (12) ◽  
pp. 282-284
Author(s):  
Radosław Wróbel ◽  
Monika Andrych-Zalewska ◽  
Wojciech Ambroszko ◽  
Szymon Fryda
Keyword(s):  
Low Frequency ◽  
Measuring System ◽  
Turbine Engines ◽  
Automotive Safety ◽  
Measuring Point ◽  
Engine Vibration ◽  
Lower Accuracy ◽  
Wide Range ◽  
On Line ◽  
Line Analysis

Vibrations are most often measured using ceramic piezoelectric sensors - accelerometers. The accelerometer uses a piezoelectric effect to measure the dynamic acceleration of its housing. They are mounted directly on the measuring system (moving or rotating, such as gearboxes, rotating blades, turbine engines or bearings). This is not their only use, because they can also be used in shock measurements, such as NCAP in the field of automotive safety or diagnostics (unfortunately they have lower accuracy than low-frequency LDV). The main advantage of using a piezoelectric accelerometer is its linearity in a wide range frequency and a huge range of work dynamics. Engine vibration measurements are usually made at different points of the engine to be independent of each other. The engine block is a characteristic measuring point because it is best available. Accelerometers are assembled by glue, screwing or magnetic connection. The obtained vibroacoustic signal is most often analyzed using Fourier analysis. The following article presents another possibility of on-line analysis: short-term wavelet analysis "on-line".

A Generalized Dynamic Conductance Model for High Intensity Discharge Lamps and its Prospective Application to Design Dimmable Electronic Ballast

2021 ◽  
pp. 59-71
Author(s):  
Biswadeep Gupta Bakshi ◽  
Biswanath Roy
Keyword(s):  
High Intensity ◽  
Supply Voltage ◽  
Low Frequency ◽  
Maximum Deviation ◽  
Design Algorithm ◽  
Electronic Ballast ◽  
Wide Range ◽  
Lamp Current ◽  
Prospective Application ◽  
Dynamic Conductance

A generalized model for high intensity discharge (HID) lamp is developed based on the Francis-Damelincourt dynamic conductance model of electric discharge by replacing the model constants A, B, C, D with four experimentally determined coefficient functions of rated lamp power and root mean square supply voltage. Experimental validation of this model is done, which shows a maximum deviation of about 5 %. Moreover, sensitivity analysis for the model coefficients is also performed, results of which conform to the physical behaviour of high pressure sodium (HPS) and metal halide (MH) lamps. This model is capable to simulate electrical characteristics of HPS and MH lamps of wide range of commercially available rated power (70–400) W fed by a wide range of supply voltage (180–250) V, 50 Hz. As a prospective application, the model is applied to design dimmable low frequency square wave electronic ballast for HID lamps. A design algorithm is proposed for this purpose. Performance analysis of the designed ballast is conducted in Matlab-Simulink environment, which shows fairly good performance of the circuit in terms of dimming accuracy (maximum deviation 2.64 %), lamp power factor (≥ 0.993), and lamp current crest factor (equal to 1.0). The model can also be utilized for designing electronic ballasts of other topologies.

scholarly journals The n–Si/p–CVD Diamond Heterojunction

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3530 ◽  
Author(s):  
Szymon Łoś ◽  
Kazimierz Paprocki ◽  
Mirosław Szybowicz ◽  
Kazimierz Fabisiak
Keyword(s):  
Energy Gap ◽  
Defect Density ◽  
Polycrystalline Diamond ◽  
Cvd Diamond ◽  
Silicon Substrates ◽  
Deposition Parameters ◽  
Current Saturation ◽  
Current Voltage ◽  
Wide Range ◽  
Wide Energy

Due to the possible applications, materials with a wide energy gap are becoming objects of interest for researchers and engineers. In this context, the polycrystalline diamond layers grown by CVD methods on silicon substrates seem to be a promising material for engineering sensing devices. The proper tuning of the deposition parameters allows us to develop the diamond layers with varying crystallinity and defect structure, as was shown by SEM and Raman spectroscopy investigations. The cathodoluminescence (CL) spectroscopy revealed defects located just in the middle of the energy gap of diamonds. The current–voltage–temperature, I−V−T characteristics performed in a broad temperature range of 77–500 K yielded useful information about the electrical conduction in this interesting material. The recorded I−V−T in the forward configuration of the n–Si/p–CVD diamond heterojunction indicated hopping trough defects as the primary mechanism limiting conduction properties. The Ohmic character of the carriers flux permitting throughout heterojunction is intensified by charges released from the depletion layer. The magnification amplitude depends on both the defect density and the probability that biasing voltage is higher than the potential barrier binding the charge. In the present work, a simple model is proposed that describes I−V−T characteristics in a wide range of voltage, even where the current saturation effect occurs.

scholarly journals Low-Frequency 1/f Noise Characteristics of Ultra-Thin AlOx-Based Resistive Switching Memory Devices with Magneto-Resistive Responses

Electronics ◽  
2021 ◽  
Vol 10 (20) ◽  
pp. 2525
Author(s):  
Jhen-Yong Hong ◽  
Chun-Yen Chen ◽  
Dah-Chin Ling ◽  
Isidoro Martínez ◽  
César González-Ruano ◽  
...  
Keyword(s):  
Resistive Switching ◽  
Empirical Relation ◽  
Low Frequency ◽  
High Resistance State ◽  
Noise Power ◽  
Memory Devices ◽  
Noise Power Spectral Density ◽  
Noise Characteristics ◽  
Wide Range ◽  
Resistance State

Low-frequency 1/f voltage noise has been employed to probe stochastic charge dynamics in AlOx-based non-volatile resistive memory devices exhibiting both resistive switching (RS) and magneto-resistive (MR) effects. A 1/fγ noise power spectral density is observed in a wide range of applied voltage biases. By analyzing the experimental data within the framework of Hooge’s empirical relation, we found that the Hooge’s parameter α and the exponent γ exhibit a distinct variation upon the resistance transition from the low resistance state (LRS) to the high resistance state (HRS), providing strong evidence that the electron trapping/de-trapping process, along with the electric field-driven oxygen vacancy migration in the AlOx barrier, plays an essential role in the charge transport dynamics of AlOx-based RS memory devices.

The Attenuation of Very Low Frequency Brain Oscillations in Transitions from a Rest State to Active Attention

2009 ◽  
Vol 23 (4) ◽  
pp. 191-198 ◽  
Author(s):  
Suzannah K. Helps ◽  
Samantha J. Broyd ◽  
Christopher J. James ◽  
Anke Karl ◽  
Edmund J. S. Sonuga-Barke
Keyword(s):  
Brain Activity ◽  
Sampling Rate ◽  
Low Frequency ◽  
Future Research ◽  
Adhd Symptoms ◽  
Default Mode ◽  
Very Low Frequency ◽  
Wide Range ◽  
Interference Hypothesis ◽  
Mode Interference

Background: The default mode interference hypothesis ( Sonuga-Barke & Castellanos, 2007 ) predicts (1) the attenuation of very low frequency oscillations (VLFO; e.g., .05 Hz) in brain activity within the default mode network during the transition from rest to task, and (2) that failures to attenuate in this way will lead to an increased likelihood of periodic attention lapses that are synchronized to the VLFO pattern. Here, we tested these predictions using DC-EEG recordings within and outside of a previously identified network of electrode locations hypothesized to reflect DMN activity (i.e., S3 network; Helps et al., 2008 ). Method: 24 young adults (mean age 22.3 years; 8 male), sampled to include a wide range of ADHD symptoms, took part in a study of rest to task transitions. Two conditions were compared: 5 min of rest (eyes open) and a 10-min simple 2-choice RT task with a relatively high sampling rate (ISI 1 s). DC-EEG was recorded during both conditions, and the low-frequency spectrum was decomposed and measures of the power within specific bands extracted. Results: Shift from rest to task led to an attenuation of VLFO activity within the S3 network which was inversely associated with ADHD symptoms. RT during task also showed a VLFO signature. During task there was a small but significant degree of synchronization between EEG and RT in the VLFO band. Attenuators showed a lower degree of synchrony than nonattenuators. Discussion: The results provide some initial EEG-based support for the default mode interference hypothesis and suggest that failure to attenuate VLFO in the S3 network is associated with higher synchrony between low-frequency brain activity and RT fluctuations during a simple RT task. Although significant, the effects were small and future research should employ tasks with a higher sampling rate to increase the possibility of extracting robust and stable signals.

scholarly journals Quantification of assembly forces during creation of head-neck taper junction considering soft tissue bearing: a biomechanical study

Arthroplasty ◽  
2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Toni Wendler ◽  
Torsten Prietzel ◽  
Robert Möbius ◽  
Jean-Pierre Fischer ◽  
Andreas Roth ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Work Experience ◽  
Soft Tissues ◽  
Force Sensor ◽  
Biomechanical Study ◽  
Measuring System ◽  
Wide Range ◽  
Head Neck

Abstract Background All current total hip arthroplasty (THA) systems are modular in design. Only during the operation femoral head and stem get connected by a Morse taper junction. The junction is realized by hammer blows from the surgeon. Decisive for the junction strength is the maximum force acting once in the direction of the neck axis, which is mainly influenced by the applied impulse and surrounding soft tissues. This leads to large differences in assembly forces between the surgeries. This study aimed to quantify the assembly forces of different surgeons under influence of surrounding soft tissue. Methods First, a measuring system, consisting of a prosthesis and a hammer, was developed. Both components are equipped with a piezoelectric force sensor. Initially, in situ experiments on human cadavers were carried out using this system in order to determine the actual assembly forces and to characterize the influence of human soft tissues. Afterwards, an in vitro model in the form of an artificial femur (Sawbones Europe AB, Malmo, Sweden) with implanted measuring stem embedded in gelatine was developed. The gelatine mixture was chosen in such a way that assembly forces applied to the model corresponded to those in situ. A study involving 31 surgeons was carried out on the aforementioned in vitro model, in which the assembly forces were determined. Results A model was developed, with the influence of human soft tissues being taken into account. The assembly forces measured on the in vitro model were, on average, 2037.2 N ± 724.9 N, ranging from 822.5 N to 3835.2 N. The comparison among the surgeons showed no significant differences in sex (P = 0.09), work experience (P = 0.71) and number of THAs performed per year (P = 0.69). Conclusions All measured assembly forces were below 4 kN, which is recommended in the literature. This could lead to increased corrosion following fretting in the head-neck interface. In addition, there was a very wide range of assembly forces among the surgeons, although other influencing factors such as different implant sizes or materials were not taken into account. To ensure optimal assembly force, the impaction should be standardized, e.g., by using an appropriate surgical instrument.

Investigation of Low-Frequency Noise Characteristics in Gated Schottky Diodes

2021 ◽  
Vol 42 (3) ◽  
pp. 442-445
Author(s):  
Dongseok Kwon ◽  
Wonjun Shin ◽  
Jong-Ho Bae ◽  
Suhwan Lim ◽  
Byung-Gook Park ◽  
...  
Keyword(s):  
Schottky Diodes ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Noise Characteristics

scholarly journals The Band-Gap Studies of Short-Period CdO/MgO Superlattices

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Ewa Przeździecka ◽  
P. Strąk ◽  
A. Wierzbicka ◽  
A. Adhikari ◽  
A. Lysak ◽  
...  
Keyword(s):  
Band Gap ◽  
Layer Thickness ◽  
Energy Gap ◽  
Band Gaps ◽  
Short Period ◽  
Wide Range ◽  
Salt Structure ◽  
Short Period Superlattices ◽  
Direct Band ◽  
Sublayer Thickness

AbstractTrends in the behavior of band gaps in short-period superlattices (SLs) composed of CdO and MgO layers were analyzed experimentally and theoretically for several thicknesses of CdO sublayers. The optical properties of the SLs were investigated by means of transmittance measurements at room temperature in the wavelength range 200–700 nm. The direct band gap of {CdO/MgO} SLs were tuned from 2.6 to 6 eV by varying the thickness of CdO from 1 to 12 monolayers while maintaining the same MgO layer thickness of 4 monolayers. Obtained values of direct and indirect band gaps are higher than those theoretically calculated by an ab initio method, but follow the same trend. X-ray measurements confirmed the presence of a rock salt structure in the SLs. Two oriented structures (111 and 100) grown on c- and r-oriented sapphire substrates were obtained. The measured lattice parameters increase with CdO layer thickness, and the experimental data are in agreement with the calculated results. This new kind of SL structure may be suitable for use in visible, UV and deep UV optoelectronics, especially because the energy gap can be precisely controlled over a wide range by modulating the sublayer thickness in the superlattices.

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