Microsecond fast, battery powered, 100 kV modular pulse charger utilizing pulse transformers.

Multiple pulse charging modules were designed and tested for synchronous use in scaled experiments. The pulse chargers are each capable of charging a nanofarad-sized capacitive load to 100 kV in less than 10 µs. This is achieved by initially charging a microfarad-sized capacitor to a maximum of 3 kV, then, using a thyristor switch, discharging the capacitor into two transformers paralleled on the primary side. Each transformer steps the voltage up to 50 kV, with the transformer having opposing polarities and a common neutral on the secondary. Thus, the full 100 kV is obtained by placing the nanofarad-sized capacitor between the +50 and -50 kV terminals. The pulse chargers use a microcontroller to monitor and control the pulse charger in addition to communicating with the user as well as other pulse chargers. For increased battery life, each pulse charger is kept in a low-power state while not in use. Upon startup, the pulse chargers automatically detect the number of modules in the system, the position of itself in the system, and the timing delays associated with each pulse charger in the system. This information is essential for synchronous charging and provides individual information and controls for the pulse chargers.

Apparatus for skidding sensitivity testing of energetic materials.

A remote-operated apparatus for testing the detonation sensitivity of energetic materials is detailed. Using an air ram and rotating disk, the normal force and transverse velocity of the impact plane are controlled independently, enabling the exploration of varying impact conditions over a wide parameter space. A microcontroller local to the apparatus is used to automate apparatus operation and ensure temporal alignment of the impacting ram head with the rotating disk. Calculation of the firing parameters and issuing of operational commands are handled by a remote computer and relayed to the local microcontroller for execution at the hardware level. Impact forces are taken from fast strain measurements obtained from gauges incorporated into the ram head. Infrared imaging of explosive samples provides insight into the peak thermal temperatures experienced at the sample surface during the impact event.

Scientific evidence based rare disease research discovery with research funding data in knowledge graph.

BACKGROUND: Limited knowledge and unclear underlying biology of many rare diseases pose significant challenges to patients, clinicians, and scientists. To address these challenges, there is an urgent need to inspire and encourage scientists to propose and pursue innovative research studies that aim to uncover the genetic and molecular causes of more rare diseases and ultimately to identify effective therapeutic solutions. A clear understanding of current research efforts, knowledge/research gaps, and funding patterns as scientific evidence is crucial to systematically accelerate the pace of research discovery in rare diseases, which is an overarching goal of this study. METHODS: To semantically represent NIH funding data for rare diseases and advance its use of effectively promoting rare disease research, we identified NIH funded projects for rare diseases by mapping GARD diseases to the project based on project titles; subsequently we presented and managed those identified projects in a knowledge graph using Neo4j software, hosted at NCATS, based on a pre-defined data model that captures semantics among the data. With this developed knowledge graph, we were able to perform several case studies to demonstrate scientific evidence generation for supporting rare disease research discovery. RESULTS: Of 5001 rare diseases belonging to 32 distinct disease categories, we identified 1294 diseases that are mapped to 45,647 distinct, NIH-funded projects obtained from the NIH ExPORTER by implementing semantic annotation of project titles. To capture semantic relationships presenting amongst mapped research funding data, we defined a data model comprised of seven primary classes and corresponding object and data properties. A Neo4j knowledge graph based on this predefined data model has been developed, and we performed multiple case studies over this knowledge graph to demonstrate its use in directing and promoting rare disease research. CONCLUSION: We developed an integrative knowledge graph with rare disease funding data and demonstrated its use as a source from where we can effectively identify and generate scientific evidence to support rare disease research. With the success of this preliminary study, we plan to implement advanced computational approaches for analyzing more funding related data, e.g., project abstracts and PubMed article abstracts, and linking to other types of biomedical data to perform more sophisticated research gap analysis and identify opportunities for future research in rare diseases.

Pulsed characterization of a UV LED for pulsed power applications on a silicon carbide photoconductive semiconductor switch.

The electrical and optical characteristics of a high-power UV light emitting diode (LED) (365 nm wavelength) were evaluated under pulsed operating conditions at current amplitudes several orders of magnitude beyond the LED's manufacturer specifications. Geared towards triggering of photoconductive semiconductor switches (PCSSs) for pulsed power applications, measurements were made over varying pulse widths (25 ns-100 µs), current (0 A-250 A), and repetition rates (single shot-5 MHz). The LED forward voltage was observed to increase linearly with increasing current (∼3.5 V-53 V) and decrease with increasing pulse widths. The peak optical power observed was >30 W, and a maximum system efficiency of 23% was achieved. The evaluated LED and auxiliary hardware were successfully used as the optical trigger source for a 4H-SiC PCSS. The lowest measured on-resistance of SiC was approximately 67 kΩ.

Pulsed magnetic field excitation sensitivity of match-type electric blasting caps.

This paper presents a study on energy deposition and electromagnetic compatibility of match-type electroexplosive devices (EEDs), which recently have found more usage in pulsed power environments with high electromagnetic interference (EMI) background. The sensitivity of these devices makes them dangerous to intended and unintended radiation produced by devices commonly used in pulsed power environments. Match-type EEDs have been found to be susceptible to such low levels of energy (7-8 mJ) that safe operation of these EEDs is vital when in use near devices that produce high levels of pulsed EMI. The scope of this paper is to provide an investigation that incorporates results of similar studies to provide detonation characteristics of these EEDs. The three topics included in this study are sensitivity testing, modeling of the thermodynamic heat propagation, and electromagnetic compatibility from pulsed electromagnetic radiation. The thermodynamic joule heating of the primary explosive has been modeled by a solution to the 1D heat equation. A simple pulsed generator, Marx generator with an inductive load, was used for the electromagnetic compatibility assessment of the coupled field between the pulse generator and shorted EED. The results of the electromagnetic compatibility assessment relate the resistive, inductive, and capacitive components of the pulse generator to the area of the shorted EED.