Multi-phase Series Research Articles

Digital Control of Multiphase Series Capacitor Buck Converter Prototype for the Powering of HL-LHC Inner Triplet Magnets

Digital Control of Multiphase Series Capacitor Buck Converter Prototype for the Powering of HL-LHC Inner Triplet Magnets

A control strategy for multiphase series capacitor boost converter with automatic current sharing and n-times gain capability

Inspired by the advantages of multiphase series capacitor boost converter, its automatic current sharing and N-times gain control strategy is proposed and investigated. Theoretical analysis is developed through capacitor charge balance and inductance volt-second balance. Then the constraint conditions of operating modes time are obtained to balance the phase current and achieve N-times gain. The final control strategy was obtained by the optimized timing sequence arrangement of the modes. The proposed control strategy is applied in 4-phase series capacitor Boost converter for CCM operation for duty cycle 0 to 1. Without any additional sensors or other devices, the automatic current sharing is achieved. The current of each phase is automatically distributed evenly among the phases, and N-times voltage gain is achieved. Finally, simulation results are given to verify the analysis of the proposed control strategy.

Wide input/output control strategy for multiphase series capacitor bidirectional DC–DC converters

The series capacitor converter is one kind of high-gain bidirectional DC–DC converter based on interleaved and switched capacitor techniques. For the n-phase series capacitor converter, n times voltage gain when compared with the traditional boost converter under a specific duty cycle, as well as automatic current sharing among phases can be achieved. The specific duty cycle is (n − 1)/n to 1 in the boost mode and 0 to 1/n in the buck mode, which means that it is not suitable for wide input and/or wide output applications. To solve this issue, an 180° interleaved switching strategy is proposed in this paper. The proposed strategy is more suitable for converters to widen the working duty cycle range. The working principle, voltage gain and current distribution/sharing characteristics with the duty cycle ranging from 0 to 1 are analyzed and calculated in greater detail. In addition, as one of the n-phase series capacitor converters, a small signal model of a three-phase series capacitor converter is built, and a dual closed-loop controller is studied and designed. Finally, an experimental prototype with an input voltage that varies from 10 to 30 V and an output voltage of 100 V is built and tested. Results obtained with the prototype verify the correctness of the proposed switching strategy.

Establishing a comprehensive census of undergraduate economics curricula: Foundational and special requirements for major programs in the U.S.

This study is the first of a series of studies, collectively embodying a multiphase mixed methods design. The overall objective of these studies is to explore and address a variety of issues and features of the discipline of economics, particularly as they relate to and represent past present and future factors of globalization, education, citizenship, and society. This is done by collecting and analyzing data on numerous aspects of the undergraduate economics curriculum, economics as a discipline, and economics as applied in the real world. The overall purpose of these studies is to inform ongoing debates concerning the future of the discipline of economics and how it is taught, by examining and creating paradigms and methods that may be of aide. Additionally these studies collectively aim to outline, and in small ways develop, potential technological and organizational solutions for detailed longitudinal curriculum tracking. The frameworks employed and developed in these studies may eventually be scaled and adapted for all sorts of curricula. Ideally, the completion of this study’s overall objective yields practical insights and tools that empower faculty and departments, in economics and eventually in general, to better understand and design their own curriculum. This immediate study fills gaps in and updates data on the curriculum of undergraduate economics majors in U.S. institutions, while also establishing a baseline data set for future studies to build on. A qualitative census methodology is adapted and employed to explore how various institutional and program factors relate to certain types of major program requirements. Descriptive statistics are used for analysis, primarily to allow for comparisons to previous studies. In sum, the purpose of the data collected and analyzed in this census is to give a glimpse into the current state of the undergraduate economics curriculum in the U.S., and to inform the qualitative, quantitative, and transformative studies that are to follow in this multiphase series.

Possibilities for improving the diagnosis of clinically significant prostate cancer based on 3D modeling.

e17617 Background: The purpose of the study was improving the accuracy of diagnosis of clinically significant prostate cancer, using 3D models based on multiparametric MRI. Methods: We examined a total of 126 patients using a 12-point transrectal biopsy supplemented with an MRI targeted biopsy. The study included patients with a PSA in plasma of 1-20 ng / ml and symptoms of the lower urinary tract. We used a GE Signa HD 1.5T tomograph and an Advantage workstation. The scanning protocol included DWI, T2-FS, T2, 3D-Cube and a multiphase series with contrast. We evalueted focal changes in the structure of the prostate during MRI, using the PiRads v2.0 system, the results were processed at the GEAW 4.7 workstation, the prostate gland, urethra, seminal vesicles and sections were separated in layers. In the final 3D model, the prostate was labeled transparent, the urethra and seminal vesicles were labeled white. This model was saved and used as a visual three-dimensional image of the volume, size and localization of the foci of the prostate gland. When conducting a standard 12-point biopsy of the prostate under ultrasound control, based on a visual analysis of the 3D model, 2 additional injections were made into each part of the prostate, graded according to the PiRads≥ 3 scale. Results: We compared MRI with the histological results of a 12-point biopsy on the main 3D models of the prostate gland Among 126 patients, changes in MRI using the PiRads v2.0 system had 3 points in 48, PiRads 4 points - 32, PiRads 5 in 46 Among patients with PiRads 3 who underwent a standard 12-point biopsy, supplemented by targeted biopsy based on analysis of 3D models after MRI in 4 (8.3%) revealed clinically significant prostate cancer. Among patients with PiRads 4, clinically significant cancer was found in 11 (34.4%). In patients with PiRads 5, clinically significant cancer was found in 33 (71.7%). Conclusions: A transrectal biopsy of the prostate (using 3D modeling based on MRI with focal marking according to PI-RADS v2.0) allows to effectively identify clinically significant prostate cancer. Performing a transrectal biopsy of the prostate based on 3D modeling is the result of the effective application of an interdisciplinary approach to solving the problem of diagnosing clinically significant prostate cancer.

Establishing a Comprehensive Census of Undergraduate Economics Curricula: Foundational and Special Requirements for Major Programs in the U.S.

This study is the first of a series of studies, collectively embodying a multiphase mixed methods design. The overall objective of these studies is to explore and address a variety of issues and features of the discipline of economics, particularly as they relate to and represent past present and future factors of globalization, education, citizenship, and society. This is done by collecting and analyzing data on numerous aspects of the undergraduate economics curriculum, economics as a discipline, and economics as applied in the real world. The overall purpose of these studies is to inform ongoing debates concerning the future of the discipline of economics and how it is taught, by examining and creating paradigms and methods that may be of aide. Additionally these studies collectively aim to outline, and in small ways develop, potential technological and organizational solutions for detailed longitudinal curriculum tracking. The frameworks employed and developed in these studies may eventually be scaled and adapted for all sorts of curricula. Ideally, the completion of this study’s overall objective yields practical insights and tools that empower faculty and departments, in economics and eventually in general, to better understand and design their own curriculum. This immediate study fills gaps in and updates data on the curriculum of undergraduate economics majors in U.S. institutions, while also establishing a baseline data set for future studies to build on. A qualitative census methodology is adapted and employed to explore how various institutional and program factors relate to certain types of major program requirements. Descriptive statistics are used for analysis, primarily to allow for comparisons to previous studies. In sum, the purpose of the data collected and analyzed in this census is to give a glimpse into the current state of the undergraduate economics curriculum in the U.S., and to inform the qualitative, quantitative, and transformative studies that are to follow in this multiphase series.

Optimal scan delay depending on contrast material injection duration in abdominal multi-phase computed tomography of pancreas and liver in normal Beagle dogs.

This study was conducted to establish the values for optimal fixed scan delays and diagnostic scan delays associated with the bolus-tracking technique using various contrast material injection durations in canine abdominal multi-phase computed tomography (CT). This study consisted of two experiments employing the crossover method. In experiment 1, three dynamic scans at the porta hepatis were performed using 5, 10 and 15 sec injection durations. In experiment 2, two CT scans consisting of five multi-phase series with different scan delays of 5 sec intervals for bolus-tracking were performed using 5, 10 and 15 sec injection duration. Mean arrival times to aortic enhancement peak (12.0, 15.6, and 18.6 sec for 5, 10, and 15 sec, respectively) and pancreatic parenchymal peak (17.8, 25.1, and 29.5 sec) differed among injection durations. The maximum mean attenuation values of aortas and pancreases were shown at the scan section with 0 and 5, 0 and 10 and 5 and 10 sec diagnostic scan delays during each injection duration, respectively. The optimal scan delays of the arterial and pancreatic parenchymal phase in multi-phase CT scan using fixed scan delay or bolus-tracking should be determined with consideration of the injection duration.

A multiphase series-resonant converter with a new topology and a reduced number of thyristors

Multiphase series resonant (SR) power converters provide a flexible way to transform power between a utility grid and a multiphase load or source. The current implementations all suffer from a high component count, which makes the use of these power converters unattractive from an economical point of view. A new topology for multiphase SR power converters has been proposed in the literature in a simulation context. This topology uses half the number of power semiconductors compared to the existing multiphase SR power converters. The present paper addresses the implementation of the new topology in a prototype power converter. The old and new topologies are presented. The operation of the new topology is explained. In the new topology the resonant circuit is grounded at one side, which compared to the old topology imposes a restriction on the operation. The paper shows both simulation data and measured waveforms. It is explained that the economical gain due to the reduction in component count is offset by a lower power rating. The paper finishes with conclusions and acknowledgments.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

EXACT AND ASYMPTOTIC SOLUTIONS OF SYSTEMS WITH TURNING POINTS

A system of linear ordinary differential equations with analytic coefficients and small parameters on the derivative is considered. In a neighborhood of a turning point a new representation is constructed for the exact solution of the system in the form of a multiphase series. It is proved that this series converges uniformly with respect to the parameter. An expression is obtained for the Stokes constant at the maximal exponential. Bibligraphy: 10 titles.