Pulse Generation System Research Articles

Completely explosive ultracompact high-voltage nanosecond pulse-generating system

A conventional pulsed power technology has been combined with an explosive pulsed power technology to produce an autonomous high-voltage power supply. The power supply contained an explosive-driven high-voltage primary power source and a power-conditioning stage. The ultracompact explosive-driven primary power source was based on the physical effect of shock-wave depolarization of high-energy Pb(Zr52Ti48)O3 ferroelectric material. The volume of the energy-carrying ferroelectric elements in the shock-wave ferroelectric generators (SWFEGs) varied from 1.2 to 2.6cm3. The power-conditioning stage was based on the spiral vector inversion generator (VIG). The SWFEG-VIG system demonstrated successful operation and good performance. The amplitude of the output voltage pulse of the SWFEG-VIG system exceeded 90kV, with a rise time of 5.2ns.

Pulsed neutron generator system for astrobiological and geochemical exploration of planetary bodies

A pulsed neutron/gamma-ray detection system for use on rovers to survey the elemental concentrations of Martian and Lunar surface and subsurface materials is evaluated. A robotic survey system combining a pulsed neutron generator (PNG) and detectors (gamma ray and neutron) can measure the major constituents to a depth of about 30cm. Scanning mode measurements can give the major elemental concentrations while the rover is moving; analyzing mode measurements can give a detailed elemental analysis of the adjacent material when the rover is stationary. A detailed map of the subsurface elemental concentrations will provide invaluable information relevant to some of the most fundamental astrobiological questions including the presence of water, biogenic activity, life habitability and deposition processes.

Practice Advisory for the Perioperative Management of Patients with Cardiac Rhythm Management Devices: Pacemakers and Implantable Cardioverter–Defibrillators

Practice Advisory for the Perioperative Management of Patients with Cardiac Rhythm Management Devices: Pacemakers and Implantable Cardioverter–Defibrillators

Pulsed Operation of a Compact Fusion Neutron Source Using a High-Voltage Pulse Generator Developed for Landmine Detection

Preliminary experimental results of pulsed neutron source based on a discharge-type beam fusion called Inertial Electrostatic Confinement Fusion (IECF) for landmine detection are presented. In Japan, a research and development project for constructing an advanced anti-personnel landmine detection system by using IECF, which is effective not only for metal landmines but also for plastic ones, is now in progress. This project consists of some R&D topics, and one of them is R&D of a high-voltage pulse generator system specialized for landmine detection, which can be used in the severe environment such as that in the field in Afghanistan. Thus a prototype of the system for landmine detection was designed and fabricated in consideration of compactness, lightness, cooling performance, dustproof and robustness. By using this prototype pulse generator system, a conventional IECF device was operated as a preliminary experiment. As a result, it was confirmed that the suggested pulse generator system is suitable for landmine detection system, and the results follow the empirical law obtained by the previous experiments. The maximum neutron production rate of 2.0×108 n/s was obtained at a pulsed discharge of -51 kV, 7.3 A.

Transient flow analysis of pulse-jet generating system in ceramic filter

In an experimental set-up of pulse-jet generating system, the instantaneous velocity of pulse-jet from nozzle was measured and the transient flowrate of the pulse-jet nozzle was determined. The influences of reservoir pressure and pulse duration were discussed. The results show that the pulse-jet flowrate increases with the reservoir pressure. The long pulse duration results in an increase of the duration of the pulse-jet and has no influence on the maximum mass flowrate of the pulse-jet. The gas flow from the reservoir was treated as an adiabatic process to calculate the mass consumption of compressed gas per pulse. Based on flow transients theory and thermodynamic relations, a dynamic model was presented for the pulse-generating system consisting of pulse gas reservoir, nozzle, solenoid valve and connecting pipelines. The model was used to simulate the variations of the pulse-jet consumption and the mass flowrate versus time. The modeling results of the mass flowrate agree well with the experimental data. The effects of pulse nozzle diameter, compressed gas reservoir volume, and interconnecting pipeline length on mass flowrate of the pulse-jet cleaning system were analyzed. The results show that the dynamic model can be applied to optimize the design of the pulse cleaning system of industrial ceramic filters.

An ultrafast time-resolved fluorescence spectroscopy system for metal ion complexation studies with organic ligands

A dedicated spectrofluorimeter using ultrashort laser pulses as an excitation source was developed to measure the fluorescence properties of organic ligands for metal ion complexation with organic ligands. The laser system consists of an oscillator system for generation of femtosecond laser pulses, an amplifier system to increase the pulse energy of the generated pulses to about 2 mJ and an optical parametrical amplifier system to provide tunable laser pulses over a wide wavelength range (280 nm–10 μm). The laser pulses were applied to the sample and the emitted fluorescence was detected using a fast-gating intensified CCD camera-based spectrometer. To verify the performance of the laser, the well-known protonation constant [Pure Appl. Chem. 69 (1997) 329] of 2,3-dihydroxybenzoic acid was determined. The fluorescence lifetime of the excited species was determined as 375±32 ps in the pH range from 1.0 to 6.0, having a fluorescence emission maximum at 438 nm. The first protonation constant was determined from fluorescence data as log K 3=3.17±0.05 at an ionic strength of 0.1 M and at 294 K exploiting the Stern–Volmer mechanism. The agreement of the protonation constant with literature data (log K 3=3.10±0.20, I=0.1 M, T=298 K [Bull. Soc. Jpn. 44 (1971) 3459]) demonstrates the excellent performance of our system. Furthermore, we determined the complex formation constant log K 1=−3.11±0.16 by measuring the fluorescence properties of the ligand for the 1:1 uranyldihydroxobenzoate complex in the pH range from 3.0 to 4.5 at ionic strength of 0.1 M and at 294 K. We also determined the complex formation constant via the fluorescence emission of the metal ion uranium(VI). The fluorescence of the uranyl ion is influenced by dynamic quenching of the non-dissociated ligand and by static quenching due to the complex formation. After correction of these effects using the determined fluorescence lifetime, the complex formation constant was calculated to be log K 1=−3.99±0.44. A 1:1 metal:ligand stoichiometry was determined with both measurement methods. However, the difference of the obtained formation constants and the derived standard deviations indicate a superimposition of effects with the excited-state reactions of the ligand.

Resonant antenna-source system for generation of high-power wideband pulses

High-power electromagnetic pulse sources are of interest for a variety of applications such as transient radar and for investigations concerning radio-frequency effects on electronic systems. For such work, a simple, mobile, and robust source system has been developed at the Defence Science and Technology Organization, Edinburgh, Australia. It is comprised of a pulsed-resonant transformer, a spark-gap switch, and a modified biconical antenna. The antenna is charged to a high voltage, in the order of hundreds of kV, by the transformer and then is shorted at the bicone center by the spark-gap switch. The charge energy stored in the antenna then oscillates at the resonant frequency of the system and produces high-power electromagnetic pulses. In this paper, we describe the system design, present results of numerical simulations and measurements, and discuss areas for further improvements in energy-transfer efficiency, and power output.

Evolución menstrual y reproductiva favorable en mujeres adultas, que presentaron en la adolescencia trastornos menstruales por disfunción hipotalámica con respuesta alterada al clomifeno

Hypothalamic dysfunction is a cause of menstrual disturbances in women, in whom other diseases have been discarded. This condition is characterized by a failure of the GNRH pulse generation system and is associated to psychological and environmental factors. A lack of ovulatory response to the administration of clomiphene can be a sign of bad prognosis in hypothalamic dysfunction. To report the natural history of patients with hypothalamic dysfunction and a bad or deficient response to the administration of clomiphene. Fifty patients with hypothalamic dysfunction, that consulted for menstrual disturbances at the age of 15 to 20 years old, were studied. All received clomiphene and 31 had an ovulatory response, 12 had menses without ovulation and 7 did not menstruate. Of these 19 women eleven were interviewed again about their menstrual and reproductive history, after a lapse of 9 to 17 years of loss from follow up. Eight of the eleven women had stressful events during adolescence (going away from family house in 3, starting university studies in 3, migration out of the natal country in one and non competitive physical activity in one). All restarted their menses and eight with active sexual life had spontaneous pregnancies, giving birth from two to five children. Ovulatory cycles were documented in women without active sexual life. In teenagers with hypothalamic dysfunction and menstrual disturbances, a deficient or bad response to clomiphene does not necessarily indicate a bad prognosis in terms of menses or fertility.

Analysis of Effect of Chromatic Dispersion for Wavelength Tunable Ultrashort Soliton Pulse Generation

The performance characteristics of generated soliton and anti-Stokes pulses for the wavelength tunable ultrashort soliton pulse generation system are discussed for different fiber dispersion parameters of β2 and β3 at the pump wavelength. Numerical analysis showed that the broadband wavelength tunability is improved as both the absolute value of negative β2 and the value of β3 are decreased. When β3 is the usual value, the best performance of broadband continuous wavelength tunability which broadens symmetrically to the pump wavelength is obtained for β3 of around 蜢2 psβ2/km. The reason for this is that the behaviors of both the generated soliton and anti-Stokes pulses are due to the β2. Through simulations for different fiber dispersion parameters of β2 or β3 we obtained interesting results. When β3 is negative and the zero dispersion wavelength is set at the longer wavelength side than the pump wavelength, such as around 2 μm, it is possible to convert the generated soliton into new components at the longer wavelength side over 2 μm.

Measurement of Chromatic Dispersion of Optical Fibers Using Wavelength-Tunable Soliton Pulses

The chromatic dispersion of optical fibers is measured using a compact wavelength-tunable soliton pulse generation system. In this system, an ultrashort optical pulse can be generated in a wide wavelength region and the wavelengths of the optical pulses can be changed simply by varying the fiber input power. Since the system is compact and changing the wavelength is very easy, measurement of the chromatic dispersion can be demonstrated easily using a simple setup. The magnitudes of the second- and third-order dispersions in the optical fibers are measured in the wide wavelength region from 1.32 to 1.93 µm. Since the pulse width of the soliton pulse is as narrow as 200 fs, the dispersion of the fiber can be measured in an optical fiber as short as 10 m.

Performance of pulsed power generator using high-voltage static induction thyristor

In a present pulsed power generator system using semiconductor switches, saturable magnetic switches are usually connected in series to compress the output pulse because the current rise-time of semiconductor switches are generally not short enough, However, the magnetic switches are heavy and they reduce the energy transfer efficiency. So we propose a pulsed power generator system using a 5500-V static induction thyristor (SI-Thy), a Blumlein line for pulse formation, and a step-up pulse transformer. The fundamental characteristics of the generator are evaluated. From experiments using only one SI-Thy, turn-on time of several tens of nanoseconds and the maximum rise rate of the output voltage of 115-kV//spl mu/s are obtained. It is confirmed that an SI-Thy will have sufficient performance as a main switch of the pulsed power generator for the flue gas treatment and decomposition of hazardous gases when several SI-Thys are connected in series.

Pulse Nebulization in Pneumatic Devices

Aerosols of a physiological salt solution and aqueous solutions of salbutamol, sodium cromoglicate, and dornase aifa were generated in a pneumatic nebulizer and analyzed in a system with controlled humidity of air as a carrier gas. Mass distribution of aerosol particles and yield of generation for pulse nebulization were measured. Pulsation of generation was realized with an attachment maintained by a computer program. Opening times of the valve were in the range 50-800 ms. The results indicate the possibility of improving aerosol particle delivery to the lung using a pulse generation system.

Data acquisition and pulse generation system for nuclear magnetic resonance spectrometers on a single PC-ISA compatible board

A data acquisition and pulse generation system for NMR spectrometers is described. It has been implemented on a single board for MS-DOS personal computers with an ISA standard bus interface and uses a simple architecture optimizing the integration of the hardware and software resources. The system, owing to its versatility and low cost, is particularly suitable to upgrade old pulsed NMR instruments with outdated data and control systems, for applications where expensive new cryomagnetic instruments would be inappropriate, such as in industrial control or as educational tools. The board provides two simultaneous data acquisition channels allowing 250 000 12-bit conversions per second per channel, including real-time signal averaging, and is able to produce essentially any pulse sequence on several output lines. The duration of each pulse can range from s to 180 s with a minimum pulse separation of s and with a resolution of s. All classic NMR pulse sequences are allowed in addition to those required for self-diffusion coefficient measurements using pulsed magnetic field gradients. All functions of the system are managed by machine-language routines callable from within a VisualBASIC program. The cost of the hardware of this device is under US$500.

Fiber-laser-based femtosecond parametric generator in bulk periodically poled LiNbO_3

A diode-pumped system for optical parametric generation of wavelength-tunable femtosecond pulses is demonstrated. It comprises an Er-doped fiber mode-locked laser, a fiber chirped-pulse amplifier, and a bulk periodically poled LiNbO(3) (PPLN) optical parametric generator. The parametric generator is pumped at 777 nm with frequency-doubled microjoule pulses from the fiber amplifier and produces 300-fs pulses tunable from 1 to 3microm with output energies up to ~200 nJ. Use of a PPLN nonlinear crystal substantially reduces the pump energies required for efficient parametric generation. Saturated single-pass parametric energy conversion of 38% (internal) has been achieved with only 220 nJ of pump inside the crystal. A parametric generation threshold of 54 nJ is observed, and efficient parametric conversion is obtained with repetition rates up to 200 kHz.

The Impact of Pulse Generator Longevity on the Long‐Term Costs of Cardiac Pacing

The long-term costs of cardiac pacing include the device costs, the procedural costs, the follow-up costs, and the replacement costs. At present, there is significant variability in the efficiencies of the integrated circuits and the total battery capacity among different pulse generators that will influence replacement rates over time. Accordingly, we compared the influence of pulse generator longevity on the long-term costs of pacing. The longevity of pulse generators was calculated based on the electrical characteristics of the device and the percentage of time the patient is paced. Replacement rates of pulse generators were estimated for our patient population over a 20-year period, based on patient survival and pulse generator longevity. The costs of pacing over this 20-year follow-up period were then calculated. The longevity of DDDR devices presently implanted in the United States ranges from 8-14 years, assuming that patients are paced 50% of the time. Replacement rates in this population over a 20-year follow-up period were calculated to range from 0.34-0.66, and the total costs of pacing would range from $11,898-14,900 per patient. The longevity of SSIR devices ranges from 7-20 years, assuming that patients are paced 50% of the time. Replacement rates were calculated over the 20-year follow-up period to range from 0.20-0.84, and the total costs of VVIR pacing would range from $8,331-13,286. Based on the proportion of pulse generator models implanted in patients in the United States, the maximum cost differential to the health care system is approximately $424 million/year comparing the devices with the shortest and greatest longevities. Thus, pulse generator longevity may significantly influence the long-term costs of pacing. Patient survival and pulse generator system longevity should be considered when selecting the appropriate pacing system for the individual patient.

波長可変ピコ秒赤外パルス発生システム

波長可変ピコ秒赤外パルス発生システム

Mitochondrial Calcium Uptake from Physiological-type Pulses of Calcium: A DESCRIPTION OF THE RAPID UPTAKE MODE

A controversy in the field of bioenergetics has been whether mitochondria are capable of sequestering enough Ca2+ from cytosolic Ca2+ pulses to raise their intramitochondrial free Ca2+ level ([Ca2+]m). This is significant because an increase in [Ca2+]m has been linked to an increase in cellular metabolic rate through various mechanisms. To resolve this question, we exposed isolated liver mitochondria to physiological type pulses of Ca2+ produced using a pulse-generating system (Sparagna, G. C., Gunter, K. K., and Gunter, T. E. (1994) Anal. Biochem. 219, 96-103). We then measured the resulting mitochondrial Ca2+ uptake. The uniporter was previously thought to be the only specific Ca2+ uptake mechanism in mitochondria. Our studies have uncovered an additional uptake mechanism, the rapid mode of uptake or RaM, which functions at the beginning of each pulse and allows mitochondria to sequester a considerable amount of Ca2+ from short pulses. We have shown that the RaM is reset by decreasing the [Ca2+] between pulses for a very short time, making this uptake mode ideally suited for Ca2+ sequestration from Ca2+ pulse sequences. With rapid Ca2+ uptake occurring at the beginning of each pulse, liver mitochondria may be able to sequester sufficient Ca2+ from a short sequence of pulses to activate the cellular metabolic rate.

Performance characteristics of a compact D-T neutron generator system

A new pulsed neutron generator system has been introduced which uses the deuterium-tritium fusion reaction to produce 14 MeV neutrons. The new system incorporates the latest technology in its electronics, sealed tube neutron head and computer control. The system is extremely flexible and adaptable to a wide range of applications in the field of materials non-destructive analysis.

Generation of 1-10 Ps Hard X-Rav Pulses for Time Resolved X-Ray Diffraction

We present a further improvement of our experimental system for the generation of hard x-ray pulses in the range 1-10 ps, A laser system based on a cw mode locked Nd:YLF laser is utilized for the emission of deep UV pulses at 193 nm with duration 1.5 ps and repetition rate of 300 Hz, This UV radiation is used to pump an x-ray diode which produces CuKa x-ray pulses with a duration shorter than 10 ps at 300 Hz.

A neutron activation gamma ray spectrometer for planetary surface analysis

A pulsed DT neutron generator system, similar to that used in commercial well logging, offers the possibility of performing accurate elemental analyses to depths of tens of centimeters in a few seconds with the probe on the body's surface. Through time-phased measurements of the gamma-ray spectrum synchronized with the neutron pulses, concentrations of hydrogen, carbon and key mineral forming elements can be determined even with a low-resolution spectrometer. If a high resolution spectrometer is used, the number of elements measured and the sensitivity for measurement is increased. An implanted probe system, such as in a comet or ice cap penetrator, would offer the highest possible sensitivity. An inexpensive neutron probe system based on modifications of the Schlumberger well-logging system has been proposed for the Discovery/Venera/SAGE Mission to Venus and the Mars Polar Pathfinder. Preliminary experiments on a simulated Venusian surface indicate that high quality results can be obtained.