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Moscow, Russia

Semenov S.,Keele University | Kellam J.,Carolinas Medical Center | Sizov Y.,TRINITI | Nazarov A.,INTEGRIT | And 5 more authors.
Physics in Medicine and Biology | Year: 2011

Microwave tomography (MWT) is a novel imaging modality which might be applicable for non-invasive assessment of functional and pathological conditions of biological tissues. Imaging of the soft tissue of extremities is one of its potential applications. The feasibility of this technology for such applications was demonstrated earlier. This is the first of two companion papers focused on an application of MWT for imaging of the extremity's soft tissues. The goal of this study is to assess the technical performance of the developed 2D MWT system dedicated for imaging of functional and pathological conditions of the extremity's soft tissues. Specifically, the system's performance was tested by its ability to detect signals associated with physiological activity and soft tissue interventions (circulatory related changes, blood flow reduction and a simulated compartmental syndrome) - the so-called physiological signatures. The developed 2D MWT system dedicated to the imaging of animal extremities demonstrates good technical performance allowing for stable and predictable data acquisition with reasonable agreement between the experimentally measured electromagnetic (EM) field and the simulated EM field within a measurement domain. Using the system, we were able to obtain physiological signatures associated with systolic versus diastolic phases of circulation in an animal extremity, reperfusion versus occlusion phases of the blood supply to the animal's extremity and a compartment syndrome. The imaging results are presented and discussed in the second companion paper. © 2011 Institute of Physics and Engineering in Medicine.

Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV | Year: 2010

The article proposes a fundamentally new approach to the problem of breaking high currents of 100kA or more. The vacuum discharger and the vacuum interrupter differ significantly in the rate of electric strength recovery, size of electrode erosion and etc. This is due to the difference in the type of the discharge. In the report considered we suggested that to align these values the current I should be closed through the spark gap prior to moving the electrodes of the vacuum interrupter; at this its value is above the initial by ΔI (ΔI-current, ΔI/I0 ∼5÷10•10 -2). The excess ΔI-current flows through the vacuum interrupter, but in the reverse direction. In the course of moving the electrodes apart, the ΔI-current falls to zero with a time constant t=L/R, where L and R are the inductance of the contour (vacuum interrupter- spark gap) and resistance of the discharge of the discharge gap, respectively. This makes it possible to quickly recover the electric strength of the gap between the contacts, substantially reduce the electrode erosion and significantly decrease the breaking voltage of the ΔI-current. At the final stage the discharge of the countercurrent battery recovers the vacuum strength of the discharge gap. Such method of current breaking allows for the effective interruption of direct currents of high power. The method was developed in terms of the combination current breaker (vacuum interrupter and plasma opening switch). Spark gap is replaced to mobile plasma gap in design of combination opening switch. The article considers -construction of switch; -described of action steps; -energy characteristics of circuit, in the context to progress of conception pulsed generators based on inductive storage. ©2010 IEEE.

Digest of Technical Papers-IEEE International Pulsed Power Conference | Year: 2015

The technical solutions are proposed for the pulse generator based on a transformer-like inductive storage of energy (TIS). This work describes construction and components of a single turn TIS, as well as some basic operation principles of a semi-conductor switch used in combination with the TIS the fact that there is no need in opening of the primary winding permitting one to consider a construction capable to generate high power pulses in the repetitive pulse mode is among the advantages of the proposed technical solution the next important aspect that should be noted here is the coefficient of power gain, which is ∼104 and more the poloidal current of the energy storage is among the unsolved problems. This current requires additional components that need to be introduced into the pulse generator construction with the goal of maximum possible compensation of the poloidal current. One of possible ways to solve the above problem is to use an inductively-coupled duel transformer storage the solution allows one to solve the following two problems simultaneously: compensation of the poloidal current and increase of the load current. © 2015 IEEE.

Proceedings of the 2014 IEEE International Power Modulator and High Voltage Conference, IPMHVC 2014 | Year: 2014

The process of generating series pulses and pulse trains based on inductive storage is associated with solving several common problems, such as attaining high resources of opening switches, adapting separate components of opening switch construction, and adapting load construction to solve a required task while maintaining pulse parameters. This paper proposes to consider the main parts of generation technology in providing pulse series and pulse train. © 2014 IEEE.

Digest of Technical Papers-IEEE International Pulsed Power Conference | Year: 2015

Generation of series of repetitive shots by a railgun is associated with solution of some basic and applied problems. The very first basic one is a high-density energy source with long-Time energy storage and fast-Time release of the stored energy to the load. Another ones are associated with the pulsed generator operating either without additional external power sources or, at least, with the minimum number of ones, and the time varying external magnetic field which is inherent to all railguns. All the applied problems are associated with the type of the load. The revolver railgun design is proposed to solve these problems. This design has a number of advantages over the conventional railgun design. One can see for example that the railgun discharge current decreases proportionally to number of armature in the revolver railgun while the applied voltage increases, which is subject of the equality of both mass and velocity of armature. This allows one to optimize the parameters of the inductive storage and its opening switch. The revolver railgun design also increases its own spatial stability during series of repetitive shots of armatures, as well as stability of radial component of the railgun discharge currents and stability of launched armatures, which is associated with non uniformity of the radial magnetic field. Some specific space applications of a revolver railgun combined with a space-propulsion ion engine is discussed in the Appendix. © 2015 IEEE.

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