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There are two designs of large area, vacuum interrupter contacts: the transverse magnetic field (TMF) contact and the axial magnetic field (AMF) contact. These contacts are required to perform a wide variety of roles within vacuum circuit breakers. One duty is to pass short-circuit currents with the vacuum interrupters' contacts closed for a period of time (1 to 4 seconds), after which the circuit...
We present a multi-query recovery policy for a hybrid system with goal limit cycle. The sample trajectories and the hybrid limit cycle of the dynamical system are stabilized using locally valid Time Varying LQR controller policies which probabilistically cover a bounded region of state space. The original LQR Tree algorithm builds such trees for non-linear static and non-hybrid systems like a pendulum...
In vivo visualization and quantification of surface tissue edema, or ‘tissue swelling’ following injury or as diagnostic criteria for the detection of disease remains a clinical challenge. The most common method for evaluating edema is by clinical examination, during which tissue swelling and turgor are routinely examined. This technique, however, is qualitative, difficult to standardize, and requires...
THz impulse communications is a new system concept based on an imaging radar that we have been developing for biomedical imaging applications the past ten years. Its hybrid architecture combines the high-peak-power and spread-spectrum of photoconductive-switch transmitters with the high-responsivity and broad-bandwidth (RF and video) of Schottky-rectifier receivers. The data is impressed by simple...
Experimental data for the repulsion or blow-off force FB between closed contacts carrying current were compiled in order to derive an empirical relationship for this force. The data cover a period of 65 years, and includes data from contacts in both air and in vacuum with currents ranging from 1–200 kA peak. Plotting the blow-off force vs. the current reveals a simple relationship independent of the...
Low-cost sensors for mass deployment or personal use must often be calibrated to account for poor mechanical and electrical tolerances. Equally important to the initial calibration, however, is the characterization of sensor drift. This paper presents a method for evaluating drift for inexpensive optical air quality sensors. A total of 29 calibrated sensors were circulated through a public lending...
In combination with high temperature superconductive (HTS) equipment (e.g. current limiters) or in HTS subnets, which constitute a possible option for increasing the overall efficiency of electrical power distribution systems, only vacuum interrupters can be used directly in the liquid nitrogen environment. This would, however, be desirable for economic reasons. Circuit breakers and switches, respectively,...
Circuit breakers using vacuum interrupters (VI) are often tested according to the IEC standard 62271-100. This standard specifies a series of current interruption tests to verify the operation of the circuit breaker under a variety of different failure conditions. The IEC 62271-100 standard will be updated at the end of 2016 to include additional new tests for medium voltage circuit breakers, designed...
Vacuum interrupters are required to perform a wide variety of roles within vacuum circuit breakers. One duty is to pass short-circuit currents with the vacuum interrupters' contacts closed for a period of time (1 to 4 seconds), after which the circuit breaker's mechanism must be able to open the contacts, Thus the possibility of contact welding must be minimized. The flow of current through practical...
The primary application of vacuum interrupters (VI) is to interrupt short-circuit currents during faults on electrical power systems. One common VI design uses an axial magnetic field (AMF) to force the arc to remain diffuse, thereby allowing the interruption of very high short-circuit currents. In this work, VI's with 62 mm diameter AMF contacts were short-circuit tested in a synthetic circuit at...
Vacuum circuit breakers are well established in the distribution voltage level (Us ≤ 52 kV) due to their various advantages, e.g. frequent switching operations, low life-cycle-costs, excellent arc quenching capabilities and nearly maintenance free operation. In order to establish this technology at higher voltages, Us > 52 kV, the dielectric withstand reliability must be increased. In particular,...
Vacuum circuit breakers are well established in the distribution levels of the electrical power grids. To minimize contact erosion, an RMF-contact design forces the arc to rotate. The performance of the RMF-contact designs is usually evaluated in specific model vacuum chambers with viewing ports allowing high speed cameras to observe the arc rotation. These setups differ significantly from commercial...
Diffusion MRI offers the ability to noninvasively characterize the microstructure of myocardium tissue and detect disease related pathology in cardiovascular examination. This study investigates the feasibility of in vivo cardiac diffusion MRI under free-breathing condition. A high-speed imaging technique, correlation imaging, is used to enable single-shot turbo spin echo for free-breathing cardiac...
Research into the application of THz frequency imaging to medical diagnostics has yielded a significant body of work reporting the properties of in vitro and ex vivo samples. However, there a dearth of in vivo imaging results owing to the practical difficulties of acquiring data of sufficient fidelity on living animal and/or human subjects. This limited data set has hindered widespread acceptance...
The effect of rough surface scattering on the contrast observed in THz medical imaging is explored. A Frequency Modulated Continuous Wave (FMCW) THz imaging system operating at a center frequency of 650 GHz with a time averaged bandwidth varied between ∼ 0.01% and 1% bandwidth was used to image rough surface targets to explore the effect of rough surface scattering on the contrast observed in THz...
Interoperability in sharing work through services between organizations requires understanding the perspective of each partner. Available resources and requirements are widely distributed with heterogeneous descriptions and enactments. No centralized registration and discovery process exists, nor automated means to map the variety of formal organizations within various overlapping domains, some defined...
The National Ignition Facility (NIF) is a 192-beam inertial confinement fusion machine that has been fully operational since May 2009, with more limited operation as far back as 2002. The Power Conditioning System (PCS) supports the NIF mission by driving 7680 flashlamps that pump laser slabs in the main and power amplifiers of the infrared section of the laser. On a typical target shot PCS stores...
In this paper the design of programmable bit-serial Reed-Solomon encoders is considered using the traditional Berlekamp multiplier. It is suggested that there are certain advantages to be gained by deriving the generator polynomial of the code using combinational logic, or equivalently using look-up tables, rather than using an iterative LFSR based approach. The use of the recently proposed Berlekamp-like...
Microstructured semiconductor neutron detectors (MSNDs) have long been investigated as a replacement for inefficient thin-film-coated semiconductor neutron detectors. Thin-film-coated semiconductor thermal neutron detection efficiency is restricted to 4–5%. MSNDs improved upon these devices with etched perforations into the diode backfilled with neutron conversion material. Neutron absorption and...
Future development of electrical distribution and transmission technologies is driving the development of direct current (DC) circuit breakers (CB). The absence of a natural current zero, the required short interruption time and the absorption of energy during every switching process are some of the challenges for these breakers. One possible DC CB concept is to create an "artificial" current...
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