scholarly journals Comparison of Interleaving Methods of Parallel Connected Three-Level Bi-Directional Converters

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 6
Author(s):  
Hae-In Kim ◽  
Su-Hwan Kim ◽  
Seung-Woo Baek ◽  
Hag-Wone Kim ◽  
Kwan-Yuhl Cho ◽  
...  
Keyword(s):  
Phase Difference ◽  
Power Converter ◽  
The Other ◽  
Two Phase ◽  
Circulating Current ◽  
Voltage Ripple ◽  
Other Hand ◽  
Current Ripples ◽  
Current Ripple ◽  
Interleaving Technique

The voltage and current ripples in the three-level bi-directional converter (TLBC) can be reduced by an interleaving technique that controls a phase difference between the modules of power converter. On the other hand, the inductor current ripple in TLBC is increased due to the circulating current between the modules. In this paper, the effects of two interleaving methods on a two-phase TLBC, Z-type and N-type, are investigated and compared. In particular, capacitor current ripple, and voltage ripple are compared by two interleaving methods verified through Powersim (PSIM) simulation.

Interleaved Boost Converter for Photovoltaic Energy Generation

2014 ◽  
Vol 622 ◽  
pp. 97-103
Author(s):  
V. Karthikeyan ◽  
Venkatesan Jamuna ◽  
D. Rajalakshmi
Keyword(s):  
Renewable Energy ◽  
Output Voltage ◽  
Energy Generation ◽  
Energy System ◽  
Boost Converter ◽  
Voltage Ripple ◽  
Interleaved Boost Converter ◽  
Voltaic Cell ◽  
Current Ripples ◽  
Current Ripple

Renewable energy is derived from natural resources and most commonly used renewable energy system is photovoltaic cells. DC-DC boost converter serves many purposes and usually required in many applications which has a low output voltage such as batteries, photo-voltaic cell. In this paper interleaved boost converter (IBC) topology is discussed for solar energy generation. IBC have better performance characteristics compared to a conventional boost converter due to increased efficiency. DC-DC IBC have been considered and analyzed by input current ripple and output current ripple and output voltage ripple. The waveforms of voltage and current ripples and the output voltage are obtained by using MATLAB/SIMULINK are presented. The design of inductor, capacitor and analysis of ripples has been presented.

scholarly journals Effect of temperature on growth of Pseudomonas protegens Pf-5 and Pseudomonas aeruginosa PRD-10 in LB Lennox medium

2018 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Optical Density ◽  
The Other ◽  
Temperature Adaptation ◽  
Effect Of Temperature ◽  
Metabolic Processes ◽  
Two Phase ◽  
Ph Variation ◽  
Temperature Range ◽  
Other Hand

Temperature affects growth of bacteria by influencing enzyme and growth kinetics. Specifically, evolution selects for specific temperature range in which a microbe could thrive, and thus fix the temperature range in which biomolecule structure and function are finely tuned for coping with the thermal conditions prevailing within a cell at a particular temperature. Using aerobic culture in LB Lennox medium in shake flasks, this study aimed to understand the growth of Pseudomonas protegens Pf-5 (ATCC BAA-477) and Pseudomonas aeruginosa PRD-10 (ATCC 15442) at 25, 30 and 37 oC. Experiment results revealed that P. protegens Pf-5 grew very poorly at 37 oC (with maximal optical density of 0.66), while better growth was observed at 25 and 30 oC. Specifically, P. protegens Pf-5 appeared to be better adapted to growth at 25 oC, where the maximal optical density obtained was 5.3 compared to 4.6 at 30 oC. More importantly, two phase growth behaviour was observed during growth at 30 oC where a faster initial phase of growth was followed by a slower one. Growth at 25 and 30 oC exhibited similar pH trend, which suggested similar metabolic processes was activated during growth. On the other hand, P. aeruginosa PRD-10 demonstrated a more efficient conversion of LB Lennox medium into biomass where the maximal optical density obtained at all three growth temperatures were higher than those of P. protegens Pf-5. More importantly, growth of P. aeruginosa PRD-10 exhibited a clear adaptation to growth at 25 and 37 oC, while growth at 30 oC resulted in a lower biomass yield compared to that of 25 and 37 oC. On the other hand, pH variation during culture revealed that P. aeruginosa PRD-10 likely activated similar metabolic processes at all three growth temperatures, where a higher growth temperature would result in the net secretion of more alkaline metabolites. Collectively, P. protegens Pf-5 and P. aeruginosa PRD-10 demonstrated clear temperature adaptation at an evolutionary level. In addition, experiment data suggested that P. aeruginosa PRD-10 might have co-evolved with humans on a substantial time scale resulting in a temperature preference of 37 oC over 30 oC.

scholarly journals Effect of temperature on growth of Pseudomonas protegens Pf-5 and Pseudomonas aeruginosa PRD-10 in LB Lennox medium

2018 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Optical Density ◽  
The Other ◽  
Temperature Adaptation ◽  
Effect Of Temperature ◽  
Metabolic Processes ◽  
Two Phase ◽  
Ph Variation ◽  
Temperature Range ◽  
Other Hand

Temperature affects growth of bacteria by influencing enzyme and growth kinetics. Specifically, evolution selects for specific temperature range in which a microbe could thrive, and thus fix the temperature range in which biomolecule structure and function are finely tuned for coping with the thermal conditions prevailing within a cell at a particular temperature. Using aerobic culture in LB Lennox medium in shake flasks, this study aimed to understand the growth of Pseudomonas protegens Pf-5 (ATCC BAA-477) and Pseudomonas aeruginosa PRD-10 (ATCC 15442) at 25, 30 and 37 oC. Experiment results revealed that P. protegens Pf-5 grew very poorly at 37 oC (with maximal optical density of 0.66), while better growth was observed at 25 and 30 oC. Specifically, P. protegens Pf-5 appeared to be better adapted to growth at 25 oC, where the maximal optical density obtained was 5.3 compared to 4.6 at 30 oC. More importantly, two phase growth behaviour was observed during growth at 30 oC where a faster initial phase of growth was followed by a slower one. Growth at 25 and 30 oC exhibited similar pH trend, which suggested similar metabolic processes was activated during growth. On the other hand, P. aeruginosa PRD-10 demonstrated a more efficient conversion of LB Lennox medium into biomass where the maximal optical density obtained at all three growth temperatures were higher than those of P. protegens Pf-5. More importantly, growth of P. aeruginosa PRD-10 exhibited a clear adaptation to growth at 25 and 37 oC, while growth at 30 oC resulted in a lower biomass yield compared to that of 25 and 37 oC. On the other hand, pH variation during culture revealed that P. aeruginosa PRD-10 likely activated similar metabolic processes at all three growth temperatures, where a higher growth temperature would result in the net secretion of more alkaline metabolites. Collectively, P. protegens Pf-5 and P. aeruginosa PRD-10 demonstrated clear temperature adaptation at an evolutionary level. In addition, experiment data suggested that P. aeruginosa PRD-10 might have co-evolved with humans on a substantial time scale resulting in a temperature preference of 37 oC over 30 oC.

Effects of Alloying Elements on Physical and Mechanical Properties of Co-Al-W-Based L12/fcc Two-Phase Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 1195-1200 ◽  
Author(s):  
Katsushi Tanaka ◽  
Haruyuki Inui
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Lattice Mismatch ◽  
Physical And Mechanical Properties ◽  
The Other ◽  
Alloying Elements ◽  
Alloying Element ◽  
Two Phase ◽  
Solvus Temperature ◽  
Other Hand

The changes in the γ’ solvus temperature and the volume fraction of Co-Al-W based alloys with fcc / L12 two-phase microstructures upon alloying with quaternary elements have been investigated. All investigated quaternary elements, except for Fe and Re, increase the γ’ solvus temperatures of Co-Al-W based alloys with varying efficiencies depending on quaternary element. On the other hand, the variation of the γ’ volume fraction with alloying depends on the alloying element. Of the investigated quaternary elements, Ta is found to be the most effective in increasing the γ’ solvus temperature of Co-Al-W based alloys. The lattice mismatch significantly increase upon alloying with Ta of 4at.%, which destroys the coherent cuboidal structure.

Twenty-two-year revolutions in the cosmic-ray diurnal variations

1968 ◽  
Vol 46 (10) ◽  
pp. S934-S936
Author(s):  
M. Wada ◽  
S. Kudo
Keyword(s):  
Phase Difference ◽  
Geomagnetic Activity ◽  
Radial Flow ◽  
Interplanetary Space ◽  
Cosmic Ray ◽  
Diurnal Variations ◽  
Rigid Rotation ◽  
The Other ◽  
The Sun ◽  
Other Hand

It is shown, from the data obtained during three complete sunspot cycles, that the 22-year variation in the phase of the cosmic-ray diurnal wave is associated with the 11-year revolutions of the diurnal vectors. The revolutions alternate in sense every 11 years. In order to interpret these revolutions, two perpendicular cosmic-ray streamings in interplanetary space are assumed. As both streamings undergo 11-year variations in their velocities, an ellipse is traced out by the termini of the annual vectors; the sense of revolution depends on whether the phase difference between the two is positive or negative. If, on the other hand, their periods are 11 and 22 years and if their phases coincide, the locus is a horseshoelike trajectory, which is traced twice by a to-and-fro motion during 22 years. The observed data available at this stage cannot distinguish between these possibilities. As geomagnetic activity also shows different 11-year variations alternately, its relation to the 22-year revolution in the diurnal variations is discussed. The radial flow of the cosmic-ray particles as well as the rigid rotation of the cosmic-ray gas with the sun suggested by Parker may correspond to the two streamings.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

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