Effects of Ta2O5 on the microstructure and electrical properties of ZnO linear resistance ceramics

ZnO-Al2O3-MgO-TiO2-SiO2-Ta2O5 (ZnO-based) linear resistance ceramics with doping different molar percentages of Ta2O5 were prepared by a conventional ceramics method. Effects of Ta2O5 additives on the phase composition, microstructures, and electrical properties of ZnO-based linear resistive ceramics were investigated. The results show that doping Ta2O5 can refine the grains of the main crystalline phase ZnO and the secondary crystalline phase ZnAl2O4 in terms of microstructure, and also can reduce the grain boundary barrier and optimize the I-V characteristics in terms of electrical properties. In addition, the doping of Ta2O5 can improve the stability of the resistivity , and the impedance frequency indicates that the doping of Ta2O5 makes the sample suitable for high-frequency electric fields. The resistivity of the sample doped with 0.2 mol% Ta2O5 is 56.2 Ω·cm, and this sample has the best grain boundary barrier height, nonlinear coefficient and temperature coefficient of resistance of 0.054 eV, 1.04 and -3.48×10-3 / ℃，respectively.

Cathodic Protection Design Consideration for an Offshore Flexible Riser Connected to an Impressed Current System

Flexible risers are regularly used to produce oil and gas in subsea production systems and by nature interconnect the subsea production system to the floating or fixed host facilities. Unbonded flexible pipes are made of a combination of metallic and non-metallic layers, each layer being individually terminated at each extremity by complex end fittings. Mostly submerged in seawater, the metallic parts require careful material selection and cathodic protection (CP) to survive the expected service life. Design engineers must determine whether the flexible pipe risers should be electrically connected to the host in order to receive cathodic protection current or be electrically isolated. If the host structure is equipped with a sacrificial anode system, then electrical continuity between the riser and the host structure is generally preferred. The exception is often when the riser and host structure are operated by separate organizations, in which case electrical isolation may be preferred simply to provide delineation of ownership between the two CP systems. The paper discusses these interface issues between hull and subsea where the hull is equipped with an impressed current cathodic protection (ICCP) system, and provides guidance for addressing them during flexible pipe CP design, operation, and monitoring. Specifically, CP design philosophies for flexible risers will be addressed with respect to manufacturing, installation and interface with the host structure’s Impressed Current Cathodic Protection (ICCP) system. The discussion will emphasize the importance of early coordination between the host structure ICCP system designers and the subsea SACP system designers, and will include recommendations for CP system computer modeling, CP system design operation and CP system monitoring. One of the challenges is to understand what to consider for the exposed surfaces in the flexible pipes and its multiple layers, and also the evaluation of the linear resistance of each riser segment. The linear resistance of the riser is a major determinant with respect to potential attenuation, which in turn largely determines the extent of current drain between the subsea sacrificial anode system and the hull ICCP system. To model the flexible riser CP system behavior for self-protection, linear resistance may be maximized, however the use of a realistic linear resistance is recommended for evaluation of the interaction between the host structure and subsea system. Realistic flexible linear resistance would also reduce conservatism in the CP design, potentially save time during the offshore campaign by reducing anode quantities, and also providing correct evaluation of drain current and stray currents.

REGULATION OF OUTPUT DYNAMIC CHARACTERISTICS OF ELECTRIC DISCHARGE INSTALLATIONS WITH RESERVOIR CAPACITORS

The paper reveals the dependences of the output dynamic characteristics of semiconductor electric discharge installations (EDIs) with reservoir capacitors on the features of the change in the value of their capacitance. In particular, it is substantiated that for any fixed discharge duration less than the duration of reaching the maximum discharge current, an increase in the capacitance of such storage devices causes an increase in the value of the final discharge current both at aperiodic and oscillatory discharges in the linear resistance of the technological load. The change in the value of the discharge current in the load in the case of forced interruption of this current at a certain moment of time is investigated. Based on the obtained regularities, the authors of the work proposed to use the capacitance of the EDI's capacitor, which is larger than capacitance required to implement the maximum value of the discharge current in the load. Using a capacitor with a larger capacity and a fully controlled semiconductor switch in the discharge circuit of the EDI, it is possible to obtain the required maximum current value at a shorter duration of the discharge process. Thus, it is possible to regulate the main dynamic parameters of pulse currents in the load – the rate of their rise and/or their duration by changing the value of the capacitance of the discharge capacitor EDI. This approach is expedient for increasing the productivity of EDIs, focused on the production of dispersed spark powders of metals and alloys. References 15, figures 3.

SOFTWARE FOR MEASURING OF DIFFERENTIAL RESISTANCE BY SCANNING OF DIGITAL IMAGES OF ANALOG OSCILLOGRAMS

A program for measuring the differential resistance of varistor materials by scanning digital images of analog oscillograms is described. The program was created using the languages HTML, CSS, JavaScript and Canvas technology. The software environment for its execution are Internet browsers. The program can be used to measure linear resistance, which limits the nonlinearity of current-voltage characteristics of varistor materials at high electric currents.

A simple method to estimate flow restriction for dual ventilation of dissimilar patients: The BathRC model

Background With large numbers of COVID-19 patients requiring mechanical ventilation and ventilators possibly being in short supply, in extremis two patients may have to share one ventilator. Careful matching of patient ventilation requirements is necessary. However, good matching is difficult to achieve as lung characteristics can have a wide range and may vary over time. Adding flow restriction to the flow path between ventilator and patient gives the opportunity to control the airway pressure and hence flow and volume individually for each patient. This study aimed to create and validate a simple model for calculating required flow restriction. Methods and findings We created a simple linear resistance-compliance model, termed the BathRC model, of the ventilator tubing system and lung allowing direct calculation of the relationships between pressures, volumes, and required flow restriction. Experimental measurements were made for parameter determination and validation using a clinical ventilator connected to two test lungs. For validation, differing amounts of restriction were introduced into the ventilator circuit. The BathRC model was able to predict tidal lung volumes with a mean error of 4% (min:1.2%, max:9.3%). Conclusion We present a simple model validated model that can be used to estimate required flow restriction for dual patient ventilation. The BathRC model is freely available; this tool is provided to demonstrate that flow restriction can be readily estimated. Models and data are available at DOI 10.15125/BATH-00816.

Research into the Textile-Based Signal Lines Made Using Ultrasonic Welding Technology

The article describes research into the transmission properties of textile signal lines (TSLs) made using ultrasonic welding technology. The presented TSLs are made from electroconductive, nickel coated, fabric strips welded between non-conducting textile layers. The article presents an analysis of the usability of the ultrasonic welding method for creating TSLs. This analysis shows that direct welding of an electroconductive path with the substrate increases its linear resistance, making it impossible to create a properly functioning line. This article presents an alternative method of creating the line using ultrasound welding technology.

Temperature-resilient solid-state organic artificial synapses for neuromorphic computing

Devices with tunable resistance are highly sought after for neuromorphic computing. Conventional resistive memories, however, suffer from nonlinear and asymmetric resistance tuning and excessive write noise, degrading artificial neural network (ANN) accelerator performance. Emerging electrochemical random-access memories (ECRAMs) display write linearity, which enables substantially faster ANN training by array programing in parallel. However, state-of-the-art ECRAMs have not yet demonstrated stable and efficient operation at temperatures required for packaged electronic devices (~90°C). Here, we show that (semi)conducting polymers combined with ion gel electrolyte films enable solid-state ECRAMs with stable and nearly temperature-independent operation up to 90°C. These ECRAMs show linear resistance tuning over a >2× dynamic range, 20-nanosecond switching, submicrosecond write-read cycling, low noise, and low-voltage (±1 volt) and low-energy (~80 femtojoules per write) operation combined with excellent endurance (>109 write-read operations at 90°C). Demonstration of these high-performance ECRAMs is a fundamental step toward their implementation in hardware ANNs.