Embankment damaging marine organisms and their control measures using calcium carbide

Five species of crabs and three species of fishes were the main marine organisms found damaging embankments owing to their burrowing nature. Among crabs, Scylla serrata was in the highest percentage, while among fishes, Boleopthalamus dussumieri was recorded in maximum percentage calcium carbide 10-15 per burrow was effective in eradicating the crabs.

Influence of particle properties on the erosive wear of sintered boron carbide

Sintered boron carbide is very hard, and can be an attractive material for wear-resistant components in critical applications. Previous studies of the erosion of less hard ceramics have shown that their wear resistance depends on the nature of the abrasive particles. Erosion tests were performed on a sintered boron carbide ceramic with silica, alumina and silicon carbide erodents. The different erodents caused different mechanisms of erosion, either by lateral cracking or small-scale chipping; the relative values of the hardness of the erodent and the target governed the operative mechanism. The small-scale chipping mechanism led to erosion rates typically an order of magnitude lower than the lateral fracture mechanism. The velocity exponents for erosion in the systems tested were similar to those seen in other work, except that measured with the 125 to 150 μm silica erodent. With this erodent the exponent was initially high, then decreased sharply with increasing velocity and became negative. It was proposed that this was due to deformation and fragmentation of the erodent particles. In the erosion testing of ceramics, the operative erosion mechanism is important. Care must be taken to ensure that the same mechanism is observed in laboratory testing as that which would be seen under service conditions, where the most common erodent is silica.

Comparative switching behaviour of silicon transistors and practical silicon carbide transistors

The motivation for our work is to identify a space for silicon carbide (SiC) devices in the silicon (Si) world. This paper presents a detailed experimental investigation of the switching behaviour of silicon and silicon carbide transistors (a JFET and a cascode device comprising a Si-MOSFET and a SiC-JFET). The experimental method is based on a clamped inductive load chopper circuit that puts considerable stress on the device and increases the transient power dissipation. A precise comparison of switching behaviour of Si and SiC devices on similar terms is the novelty of our work. The cascode is found to be an attractive fast switching device, capable of operating in two different configurations whose switching equivalent circuits are proposed here. The effect of limited dv/dt of the Si-MOSFET on the switching of the SiC-JFET in a cascode is also critically analysed.

Parameter extraction and calorimetric validation for a silicon carbide jfet pspice model

This paper focuses on the PSpice model of SiC-JFET element inside a SiCED cascode device. The device model parameters are extracted from the I-V and C-V characterization curves. In order to validate the model, an inductive test rig circuit is designed and tested. The switching loss is estimated both using oscilloscope and calorimeter. These results are found to be in good agreement with the simulated results.

Hydrogen sensor based on silicon carbide (SiC) MOS capacitor

Silicon carbide (SiC) based MOS capacitor devices are used for gas sensing in high temperature and chemically reactive environments. A SiC MOS capacitor structure used as hydrogen sensor is defined and simulated. The effects of hydrogen concentration, temperature and interface traps on C-V characteristics were analysed. A comparison between structures with different oxide layer types (SiO2, TiO2 and ZnO) and thicknesses (50..10nm) was conducted. The TiO2 based structure has better performance than the SiO2 and ZnO structures. Also, the performance of the SiC MOS capacitor increases at thinner oxide layers. © 2012 IEEE.

A discretized proportional base driver for Silicon Carbide Bipolar Junction Transistors

Silicon Carbide Bipolar Junction Transistors require a continuous base current in the on-state. This base current is usually made constant and is corresponding to the maximum collector current and maximum junction temperature that is foreseen in a certain application. In this paper, a discretized proportional base driver is proposed which will reduce, for the right application, the steady-state power consumption of the base driver. The operation of the proposed base driver has been verified experimentally, driving a 1200V/40A SiC BJT in a DC-DC boost converter. In order to determine the potential reduction of the power consumption of the base driver, a case with a dc-dc converter in an ideal electric vehicle driving the new European drive cycle has been investigated. It is found that the steady-state power consumption of the base driver can be reduced by approximately 63 %. The total reduction of the driver consumption is 2816 J during the drive cycle, which is slightly more than the total on-state losses for the SiC BJTs used in the converter. © 2013 IEEE.