Analytical Study on the Influence of Parasitic Elements in a Memristor

We study a memristive circuit with included parasitic elements, such as capacitance and inductance. In the multiple-scale scheme, we analytically show how the parasitic elements affect the voltage and the current. Finally, we provide an analytical expression for the intersection point coordinates, through which we discuss the functional behavior of the pinched hysteresis loop versus the operating frequency and the parasitic elements

Derailment detection and data collection in freight trains, based on a wireless sensor network

We report the development of a network of wireless ultralow-power sensors to be deployed on freight railway cars, with the main purpose of detecting derailment events and alerting the engineer in the cab of the leading locomotive. Because no power bus is available on freight cars, we plan to rely on energy scavenging from vibrations; therefore, minimization of the power consumption has been one of our main priorities. We have, therefore, focused on ultralow-power hardware and strived to reduce the time intervals during which it is in active mode, achieving an average power consumption of ~0.5 mW with an active cycle of ~20 ms every 2 s. We discuss the overall concept that we propose, including the self-initialization protocol and the communication strategy that we have developed, and present the results of measurements on a prototype network that we have implemented

Experimental analysis of overcharged Li-polymer batteries

Since safety hazards can occur during the life of a Li-ion battery, understanding its behavior under abusive conditions is important for the development of a safe cell. In this work, overcharge tests on commercial Li-polymer cells were conducted in a climatic chamber, resulting in gas evolution. A comprehensive post-mortem analysis of the abused cells was carried out: the exhaust gases were identified by gas phase chromatography coupled with a thermal conductivity detector (micro-GC/TCD), then flammable and toxic species were detected; the cathode and anode materials were analysed using scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS), while the electrolyte composition was studied by Fourier-transform infrared spectroscopy (FT-IR). Interestingly, the ambient temperature seemed to affect the degradation of the cell materials and hence the composition of the evolved gas

Study of an inductive sensor for measuring high frequency current pulses

The objective of this paper is to present a simple sensor based on Faraday’s Law together with an integration and amplifying stage and used this for measuring fast current pulses. Its behavior in time and frequency is tested by measuring Partial Discharges (PD) in electric insulation systems following the guidelines given in the standard IEC 60270. The measurements are also taken with two other sensors, a commercial high frequency current transformer and a resistive transducer, with the aim of comparing the results obtained with the proposed probe and obtaining an estimation of its sensitivity. An estimation of the uncertainty of the measurements is also calculated obtaining an error similar to other commercial devices.This research was supported by the Spanish Science and Technology Ministry under contract DPI 2009-14628-C03-02

Electromagnetic and mechanical gyro stabilization in railgun launcher

This paper presents two new strategies to provide gyroscopic stabilization for armatures launched by railgun launchers. The rotating motion of the projectile is obtained by means of an electromagnetic field or, alternatively, of an appropriately shaped bore. In the first case windings, coiled in the bore axis direction, generate a rotating magnetic field. The interaction between the field and the conducting sleeve implies a rotation of the latter. The mechanical solution consists in a helicoidally extruded square bore launcher. In this way, the projectile moves along the main axis and it rotates at the same time. Results of a theoretical analysis are reported and the feasibility of both techniques is discussed

Design of accurate rogowski coil for high transient currents

This paper deals with the design and construction of accurate Rogowski coils for the measurement of high transient currents. By means of the mutual partial inductance method, the shape of cylindrical structures applicable to the coil is analytically derived to ensure a given accuracy of the transducer, independently of the position, tilt and path of the primary wire. To this purpose, different coil configurations with the same number of turns, internal radius and cross-section area of the torus are considered and together to the defined cylindrical accessories, they are constructed by a commercial 3D printer