The formulation and revision of low voltage design guidelines for Southern Africa

Author(s):  
R. Herman
2015 ◽  
Vol 54 (4S) ◽  
pp. 04DC04 ◽  
Author(s):  
Hiroshi Fuketa ◽  
Kazuaki Yoshioka ◽  
Koichi Fukuda ◽  
Takahiro Mori ◽  
Hiroyuki Ota ◽  
...  

Author(s):  
Liran Li ◽  
◽  
Zhiwu Huang ◽  
Heng Li ◽  
Xiaohui Qu ◽  
...  

Electronically controlled pneumatic (ECP) brake systems have become popular in heavy-duty train applications because of their advantages, which include shorter stopping distances, improved handling, and less brake-shoe and wheel wear. In ECP brake systems, an improved power supply is required to support efficient and reliable operations. In this paper, we propose a new power converter for ECP brake systems, which is derived from a conventional push-pull converter. As opposed to conventional push-pull converters, we insert a clamping capacitor into the proposed circuit. This clamping capacitor simultaneously enables a greater number of operation modes for the proposed converter and absorbs the voltage spikes in the switch. The proposed converter is more suited for ECP brake applications that require high power, low voltage ripple, and high impedance. We theoretically analyze the proposed converter, and present the design guidelines. Further, we discuss the modeling and control aspects. We demonstrate the operations of the proposed model by performing both simulations and experiments.


Electricity ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 271-284
Author(s):  
Edoardo Barteselli ◽  
Luca Sant ◽  
Richard Gaggl ◽  
Andrea Baschirotto

Reverse bandgaps generate PVT-independent reference voltages by means of the sums of pairs of currents over individual matched resistors: one (CTAT) current is proportional to VEB; the other one (PTAT) is proportional to VT (Thermal voltage). Design guidelines and techniques for a CMOS low-power reverse bandgap reference are presented and discussed in this paper. The paper explains firstly how to design the components of the bandgap branches to minimize circuit current. Secondly, error amplifier topologies are studied in order to reveal the best one, depending on the operation conditions. Finally, a low-voltage bandgap in 65 nm CMOS with 5 ppm/°C, with a DC PSR of −91 dB, with power consumption of 5.2 μW and with an area of 0.0352 mm2 developed with these techniques is presented.


Author(s):  
Marek Malecki ◽  
J. Victor Small ◽  
James Pawley

The relative roles of adhesion and locomotion in malignancy have yet to be clearly established. In a tumor, subpopulations of cells may be recognized according to their capacity to invade neighbouring tissue,or to enter the blood stream and metastasize. The mechanisms of adhesion and locomotion are themselves tightly linked to the cytoskeletal apparatus and cell surface topology, including expression of integrin receptors. In our studies on melanomas with Fluorescent Microscopy (FM) and Cell Sorter(FACS), we noticed that cells in cultures derived from metastases had more numerous actin bundles, then cells from primary foci. Following this track, we attempted to develop technology allowing to compare ultrastructure of these cells using correlative Transmission Electron Microscopy(TEM) and Low Voltage Scanning Electron Microscopy(LVSEM).


Author(s):  
Marek Malecki ◽  
James Pawley ◽  
Hans Ris

The ultrastructure of cells suspended in physiological fluids or cell culture media can only be studied if the living processes are stopped while the cells remain in suspension. Attachment of living cells to carrier surfaces to facilitate further processing for electron microscopy produces a rapid reorganization of cell structure eradicating most traces of the structures present when the cells were in suspension. The structure of cells in suspension can be immobilized by either chemical fixation or, much faster, by rapid freezing (cryo-immobilization). The fixation speed is particularly important in studies of cell surface reorganization over time. High pressure freezing provides conditions where specimens up to 500μm thick can be frozen in milliseconds without ice crystal damage. This volume is sufficient for cells to remain in suspension until frozen. However, special procedures are needed to assure that the unattached cells are not lost during subsequent processing for LVSEM or HVEM using freeze-substitution or freeze drying. We recently developed such a procedure.


Author(s):  
T. Miyokawa ◽  
S. Norioka ◽  
S. Goto

Field emission SEMs (FE-SEMs) are becoming popular due to their high resolution needs. In the field of semiconductor product, it is demanded to use the low accelerating voltage FE-SEM to avoid the electron irradiation damage and the electron charging up on samples. However the accelerating voltage of usual SEM with FE-gun is limited until 1 kV, which is not enough small for the present demands, because the virtual source goes far from the tip in lower accelerating voltages. This virtual source position depends on the shape of the electrostatic lens. So, we investigated several types of electrostatic lenses to be applicable to the lower accelerating voltage. In the result, it is found a field emission gun with a conical anode is effectively applied for a wide range of low accelerating voltages.A field emission gun usually consists of a field emission tip (cold cathode) and the Butler type electrostatic lens.


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