Search results for "pump"

A spectrophotometric flow procedure for the determination of cationic surfactants in natural waters using a solenoid micro-pump for fluid propulsion

2006

An automatic flow-analysis procedure for spectrophotometric determination of cationic surfactants in surface water using a solenoid micro-pump for propelling solutions of reagents and sample is des...

Cancellation, pumping and permutation in formal languages

1984

Stability improvement of isolated multiple-output DC/DC converter using coupled inductors

2016

Coupling output inductors is a very popular solution when designing a multiple-output DC/DC system. Space-borne circuits are one of the areas where a custom DC/DC converter design with coupled inductors could be preferred to have a detailed design of all variables. Output voltage regulation can be improved using coupled output inductors on a multiple-output DC/DC converter, and, as demonstrated in this paper, it provides an enhanced stability. This paper presents the small signal analysis of a push-pull converter with seven outputs having all its output inductors coupled together and compares it theoretically to the uncoupled version to demonstrate the stability improvement. The theoretical…

Linear-non-linear digital control for dc/dc converters with fast transient response

2009

A linear-non-linear digital control for multi-module DC/DC converters that improves system stability, solves the limit-cycle problem, reduces recovery time and limits over- and under-shoots in regulated output voltage, is presented. A simulation model in Matlab-Simulink/Active-HDL mixed environment is described. Preliminary hardware tests on a single-phase step-down converter are reported. Simulation and experimental results are shown.

DC/DC converter topologies for electrolyzers: State-of-the-art and remaining key issues.

2017

In recent years, the use of electrolyzers to produce cleanly and efficiently hydrogen from renewable energy sources (i.e. wind turbines, photovoltaic) has taken advantage of a growing interest from researchers and industrial. Similarly to fuel cells, DC/DC converters are needed to interface the DC bus with the electrolyzer. Usually, electrolyzers require a low DC voltage to produce hydrogen from water. For this reason, a DC/DC buck converter is generally used for this purpose. However, other DC/DC converter topologies can be used depending on the feature of the electrolyzer and electrical grid as well. The main purpose of this paper is to present the current state-of-the-art of DC/DC conver…

Energy and spatial distribution of traps in SiO2/Al 2O3 nMOSFETs

2006

The energy and spatial profiling of the interface and near-interface traps in n-channel MOSFETs with SiO2/Al2O3 gate dielectrics is investigated by charge-pumping (CP) measurements. By increasing the amplitude as well as lowering the frequency of the gate pulse, an increase of the charge recombined per cycle was observed, and it was explained by the contributions of additional traps located higher in energy and deeper in position at the SiO2/Al2O3 interface. In addition, CP currents, acquired after different constant voltage stress, have been used to investigate the trap generation in this dielectric stack. © 2006 IEEE.

Comparison of 24-h control of gastric acidity by three different dosages of pantoprazole in patients with duodenal ulcer

1998

Background It is now clear that the extent to which gastric acid secretion must be suppressed varies with the clinical condition being treated. Aim To assess the 24-h control of gastric acidity and the individual response variability of three different doses of pantoprazole. Methods Sixty-four duodenal ulcer patients were recruited for this prospective, randomized, multicentre, double-blind, parallel-group study. They were subdivided into three well-matched groups treated with 20 mg o.m., 40 mg o.m. and 40 mg b.d. of pantoprazole, respectively. Endoscopy and intragastric pH monitoring were performed in each patient before and after 14 days of treatment. Results Fifty-five patients were elig…

Global distributions of diazotrophs nitrogen fixation rates - Depth integrated values computed from a collection of source datasets - Contribution to…

2013

The MAREDAT atlas covers 11 types of plankton, ranging in size from bacteria to jellyfish. Together, these plankton groups determine the health and productivity of the global ocean and play a vital role in the global carbon cycle. Working within a uniform and consistent spatial and depth grid (map) of the global ocean, the researchers compiled thousands and tens of thousands of data points to identify regions of plankton abundance and scarcity as well as areas of data abundance and scarcity. At many of the grid points, the MAREDAT team accomplished the difficult conversion from abundance (numbers of organisms) to biomass (carbon mass of organisms). The MAREDAT atlas provides an unprecedente…

Results of heart retransplantation: subanalysis of the Spanish Heart Transplant Registry

2021

Heart retransplantation (ReHT) is controversial in the current era. The aim of this study was to describe and analyze the results of ReHT in Spain. Methods We performed a retrospective cohort analysis from the Spanish Heart Transplant Registry from 1984 to 2018. Data were collected on donors, recipients, surgical procedure characteristics, immunosuppression, and survival. The main outcome was posttransplant all-cause mortality or need for ReHT. We studied differences in survival according to indication for ReHT, the time interval between transplants and era of ReHT. Results A total of 7592 heart transplants (HT) and 173 (2.3%) ReHT were studied (median age, 52.0 and 55.0 years, respectively…

Extraction of thermal characteristics of surrounding geological layers of a geothermal heat exchanger by 3D numerical simulations

2016

Ground thermal conductivity and borehole thermal resistance are key parameters for the design of closed Ground-Source Heat Pump (GSHP) systems. The standard method to determine these parameters is the Thermal Response Test (TRT). This test analyses the ground thermal response to a constant heat power injection or extraction by measuring inlet and outlet temperatures of the fluid at the top of the borehole heat exchanger. These data are commonly evaluated by models considering the ground being homogeneous and isotropic. This approach estimates an effective ground thermal conductivity representing an average of the thermal conductivity of the different layers crossed by perforation. In order …