The emission properties, structure and stability of ionic liquid menisci undergoing electrically assisted ion evaporation

The properties and structure of electrically stressed ionic liquid menisci experiencing ion evaporation are simulated using an electrohydrodynamic model with field-enhanced thermionic emission in steady state for an axially symmetric geometry. Solutions are explored as a function of the external background field, meniscus dimension, hydraulic impedance and liquid temperature. Statically stable solutions for emitting menisci are found to be constrained to a set of conditions: a minimum hydraulic impedance, a maximum current output and a narrow range of background fields that maximizes at menisci sizes of 0.5–3 ${\rm \mu}{\rm m}$ in radius. Static stability is lost when the electric field adjacent to the electrode that holds the meniscus corresponds to an electric pressure that exceeds twice the surface tension stress of a sphere of the same size as the meniscus. Preliminary investigations suggest this limit to be universal, therefore, independent of most ionic liquid properties, reservoir pressure, hydraulic impedance or temperature and could explain the experimentally observed bifurcation of a steady ion source into two or more emission sites. Ohmic heating near the emission region increases the liquid temperature, which is found to be important to accurately describe stability boundaries. Temperature increase does not affect the current output when the hydraulic impedance is constant. This phenomenon is thought to be due to an improved interface charge relaxation enhanced by the higher electrical conductivity. Dissipated ohmic energy is mostly conducted to the electrode wall. The higher thermal diffusivity of the wall versus the liquid, allows the ion source to run in steady state without heating.

Effect of Electric Field On Electron Mobility in Sub-100 nm InAlN/GaN High Electron Mobility Transistors

Electron mobility is important for electron velocity, transport current, output power, and frequency characteristics. In conventional mobility extraction methods, electron mobility is usually extracted directly from the measured gate capacitance (CG) and current-voltage characteristics. When device gate length (LG) scales to sub-100 nm, the determination of CG becomes more difficult not only for the measure equipment but also the enhanced effect from parasitic capacitance. Here in this paper, the CG extracted from high-frequency small-signal equipment circuit is used for the InAlN/GaN high electron mobility transistors (HEMTs). Electron mobility of the device with LG of 60-nm under VDS of 0.1 V and 10 V is extracted using two-dimensional scattering theory, respectively. The obtained results show that under a high electric field, the electron temperature (Te) and addition polarization charges (∆σ) increase, resulting in the enhanced polar optical phonon (POP) as well as polarization Coulomb field (PCF) scatterings and degradation of the electron mobility. This study makes it possible to improve the electron mobility by reducing Te and ∆σ for the InAlN/GaN HEMTs application.AlGaN/GaN heterostructure field-effect transistors with different gate lengths were fabricated. Based on the chosen of the Hamiltonian of the system and the additional polarization charges, two methods to calculate PCF scattering by the scattering theory were presented. By comparing the measured and calculated source-drain resistances, the influence of the different gate lengths on the PCF scattering potential was confirmed.

Failure Analysis of Some Commercial Spotlights Based on Light Emitting Diodes

The failure mechanism of two commercial light-emitting diode (LED)-based spotlights with GU10 form factor is analyzed. Through component testing and comparison to nominal values as well as to simulations, it is found that the cause of both device failures is related to damaged components within the drive circuits rather than the LEDs themselves. Both LED heads work as normal when connected to an external direct current (DC) source. The results show that the lack of light output of one spotlight is related to the open circuit caused by damaged resistors and inductors in its drive circuit, while the flickering of the other is related to the malfunction of the integrated circuit providing constant current output. Therefore, improving the quality of the LED drive circuits is considered the most effective way for manufacturers to reduce catastrophic failures of LED spotlights.

Development of Stand-Alone DC Energy Datalogger for Off- Grid PV System Application Based on Microcontroller

This article presents a microcontroller-based direct current (DC) energy data logger developed by adapting low-cost ATmega328 by measuring the PV system DC and voltage characteristics while simultaneously recording the measured value over time to compute the energy production Watt-hour (Wh). The prototype logger has been tested on a live 1 kW standalone PV system where the voltage sensor detects PV series array output voltage ranging between 0–50 VDC by a voltage divider sensing circuit. For accurate sensing of the current output measurement from the PV array, 50A ACS756 hall effect IC was integrated as the current sensor. The data was measured and saved in text format with comma-separated values (CSV) in an SD card, read using Microsoft Excel software. The liquid crystal display (LCD) showed the actual value of the recording process’s current, voltage, power, and duration in minutes. The recorded data has been compared to the standard laboratory digital multimeter for calibration manually to justify the measurement value. The error is minimized to 0.6% average by varying the constant float value in the programming code. The advantage of developing this logger is that the development cost is much cheaper than the standard commercial PV energy meter, can be reproduced for other DC application energy measurements, and easily modify the voltage and current range to suit the application. Apart from that, this logger also provides high accuracy performance, and its independent characteristic is practical for off-grid or off-site PV system use.

Haze Prediction Model Using Deep Recurrent Neural Network

In recent years, haze pollution is frequent, which seriously affects daily life and production process. The main factors to measure the degree of smoke pollution are the concentrations of PM2.5 and PM10. Therefore, it is of great significance to study the prediction of PM2.5/PM10 concentration. Since PM2.5 and PM10 concentration data are time series, their time characteristics should be considered in their prediction. However, the traditional neural network is limited by its own structure and has some weakness in processing time related data. Recurrent neural network is a kind of network specially used for sequence data modeling, that is, the current output of the sequence is correlated with the historical output. In this paper, a haze prediction model is established based on a deep recurrent neural network. We obtained air pollution data in Chengdu from the China Air Quality Online Monitoring and Analysis Platform, and conducted experiments based on these data. The results show that the new method can predict smog more effectively and accurately, and can be used for social and economic purposes.

Application of pulse current for dissolution of heat-resistant GS32-VI alloy

Objectives. To identify the regularities of electrochemical processing of the heat-resistant GS32-VI alloy in a sulfuric acid electrolyte with a concentration of 100 g/dm3 under the action of a pulsed current in a pulsed mode.Methods. Using the electrochemical technological complex EHK-1012 (developed by IP Tetran) and a non-compensatory method of measuring potential, polarization and depolarization curves with a change in pulse duration and a pause between them were recorded. The current pulses had an amplitude ranging from 0 to 3.5 A (when recording the polarization and depolarization curves), pulse durations ranging from 200 to 1200 ms, and a pause (delay) between pulses ranging from 50 to 500 ms. There were no reverse current pulses.Results. The parameters of the current program that provide the maximum values of the alloy dissolution rate and current output were determined: with a current pulse amplitude of 2 A, a current pulse duration of 500 ms, and a pause duration between pulses of 250 ms, the maximum dissolution rate of the alloy is 0.048 g/h·cm2, while the current output for nickel is 61.6% with an anode area of 10 cm2. The basic technological scheme for processing the heat-resistant GS32-VI alloy, which includes anodic alloy dissolution in a pulsed mode, is proposed.Conclusions. Electrochemical dissolution of GS32-VI alloy under pulsed current action results in an optimal dissolution rate ratio of the alloy components, ensuring the production of a cathode precipitate with a total nickel and cobalt content of 97.5%.

Electrochemical Biosensor for Markers of Neurological Esterase Inhibition

A novel, integrated experimental and modeling framework was applied to an inhibition-based bi-enzyme (IBE) electrochemical biosensor to detect acetylcholinesterase (AChE) inhibitors that may trigger neurological diseases. The biosensor was fabricated by co-immobilizing AChE and tyrosinase (Tyr) on the gold working electrode of a screen-printed electrode (SPE) array. The reaction chemistry included a redox-recycle amplification mechanism to improve the biosensor’s current output and sensitivity. A mechanistic mathematical model of the biosensor was used to simulate key diffusion and reaction steps, including diffusion of AChE’s reactant (phenylacetate) and inhibitor, the reaction kinetics of the two enzymes, and electrochemical reaction kinetics at the SPE’s working electrode. The model was validated by showing that it could reproduce a steady-state biosensor current as a function of the inhibitor (PMSF) concentration and unsteady-state dynamics of the biosensor current following the addition of a reactant (phenylacetate) and inhibitor phenylmethylsulfonylfluoride). The model’s utility for characterizing and optimizing biosensor performance was then demonstrated. It was used to calculate the sensitivity of the biosensor’s current output and the redox-recycle amplification factor as a function of experimental variables. It was used to calculate dimensionless Damkohler numbers and current-control coefficients that indicated the degree to which individual diffusion and reaction steps limited the biosensor’s output current. Finally, the model’s utility in designing IBE biosensors and operating conditions that achieve specific performance criteria was discussed.

Measurement-based extrapolation of spectral responsivity by using a low-NEP pyroelectric detector

In case the primary realization of the spectral responsivity scale is not conducted at all target wavelengths but at only a small part of them, one needs to extrapolate values at the specific wavelengths to an extended range. In this work, we present a fully experimental procedure to extrapolate a single value of spectral responsivity at 633 nm into the whole working wavelength range (250 – 1100) nm of Si photodiodes. It is based on spectral responsivity comparison between a Si trap detector and a low-NEP pyroelectric detector of nearly flat spectral response. For this purpose, we developed a setup specialized to compare a Si-trap detector of dc-current output with a pyroelectric detector of ac-voltage output by using a modulated probing light source and a monitoring technique. To keep the probing light chopped even for the dc-photocurrent readout, we adopted a low chopping frequency of 4 Hz and a triggered readout for the Si-trap detector, which leads to a speedy comparison between the Si-trap detector and the pyroelectric detector. For the reference pyroelectric detector, we characterized the spectral absorptivity of the black-coating and the nonlinearity of the lock-in amplifier readout. Compiling all the required information, the spectral responsivity of the Si trap detector could be measured with the minimum uncertainty of 0.3 % (k = 2), which was validated by comparing with that of our previous method based on a numerical extrapolation.