Comparison of Single-stage and Multi-stage Marx DC-DC converters for HVDC application

2018 ◽  
Author(s):  
Samir Milad Alagab ◽  
Sarath Tennakoon ◽  
Chris Gould
Keyword(s):  
Single Stage ◽  
Multi Stage

scholarly journals Extraction of tetracycline using the ionic liquid-based aqueous two phase systems: Single-stage versus multi-stage

2018 ◽  
Vol 24 (4) ◽  
pp. 387-397 ◽  
Author(s):  
Yi Liu ◽  
Li Chen ◽  
Jun Zhou ◽  
Zongcheng Yan
Keyword(s):  
Extraction Efficiency ◽  
Ph Value ◽  
Influence Factors ◽  
Volume Ratio ◽  
Line Length ◽  
Single Stage ◽  
Two Phase ◽  
Extraction Behavior ◽  
Multi Stage ◽  
Tie Line

Ionic liquids-based aqueous two-phase extraction (ILs-ATPE) offers an alternative approach to the extraction of tetracycline (TC) through their partitioning between two phases. Single-stage and multi-stage strategies have been evaluated and compared for the purification of TC using ATPE composed of 1-butyl-3-methylimidazolium halide ([Bmim]X(X=Cl,Br)) and K2HPO4. The influence factors on single-stage extraction behavior of TC were optimized systematically, including the pH value, tie line length, and volume ratio. The optimal extraction efficiency of TC could reach above 95% when the volume ratio is higher than 1.5 and the tie line length is 30.52%. The multi-stage ATPE was also investigated by simulating a three-stage crosscurrent operation in test tubes. According to the TC isotherm curve and respective McCabe?Thiele diagrams, a predicted optimized scheme of the countercurrent multi-stage ATPE was determined. TC can be purified in the IL-rich top phase with a final extraction efficiency of 99% and a final TC concentration of 0.25 mg/mL, if a three- -stage [Bmim]Cl-K2HPO4 ATPE with volume ratio of 0.5 and tie line length of 30.52% was employed. Thus, the multi-stage extraction with small volume ratio is necessary to achieve a higher recovery yield, resulting in the reduction of the IL consumption.

Mean Sojourn Time in Multi Stage Fork-Join Network

2015 ◽  
Vol 6 (3) ◽  
pp. 80-99 ◽  
Author(s):  
Yonit Barron
Keyword(s):  
Supply Chains ◽  
Sojourn Time ◽  
Computer Processing ◽  
Single Stage ◽  
Assembly Systems ◽  
Parallel Tasks ◽  
Multi Stage ◽  
Stage System ◽  
Major Factors ◽  
Performance Behavior

Fork-Join queue networks (F-J) have received increasing attention during the last Decade, due to their ability to model parallel and distributed computer processing, supply chains and assembly systems. However, most research is focused on a single stage processing, and only scant work exists on F-J with two or more stages. In this paper, the author investigates (through simulation) the performance behavior of a multi-stage system; in particular, the performance of a synchronized system is compared to an unsynchronized system regarding three major factors: (1) the number of parallel tasks; (2) the number of serial stages and (3) the utilization.

Comparative Simulation Study of Multi Stage Hybrid All Optical Fiber Amplifiers in Optical Communications

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
IS Amiri ◽  
Ahmed Nabih Zaki Rashed ◽  
P. Yupapin
Keyword(s):  
Optical Fiber ◽  
Communication Systems ◽  
Single Stage ◽  
Fiber Amplifiers ◽  
Multi Stage ◽  
Raman Amplifiers ◽  
All Optical ◽  
Optical Communication Systems ◽  
Optical Fiber Amplifiers ◽  
Hybrid Configuration

AbstractThis study clarifies the comparison between hybrid all optical fiber amplifiers in single-stage and multi-stage amplification. EDFA/Raman, Raman/EDFA/Raman, and EDFA/Raman/EDFA configurations are employed for upgrading optical communication systems. Single-stage Raman amplifiers clarifies very better performance than single-stage EDFA amplifier. Multi-stage Raman/EDFA/Raman also outlines very better performance than other hybrid configuration up to 475 km distance. Single-stage Raman amplification has outlined maxi. Q factor up to 218.392 for 250 km distance and 11.937 up to 475 km propagation range. So hybrid all optical amplifiers are essentially for upgrading optical system performance efficiency.

Limiting Factors in Single Stage Centrifugal Superchargers for Aero Engines

1940 ◽  
Vol 44 (358) ◽  
pp. 775-790
Author(s):  
K. Kollman
Keyword(s):  
High Performance ◽  
Single Stage ◽  
Limiting Factors ◽  
General Construction ◽  
Multi Stage ◽  
Aero Engines

To-day all altitudes up to, and including, the stratosphere are within the scope of aviation. The engines must therefore be provided with highly developed superchargers so as to obtain high performance even at these altitudes. The single or multi-stage superchargers necessary to accomplish this become an integral part of the engine and exercise a distinct influence on its general construction.In many types of engine the supercharger is built on to the accessory drive end, that is the rear of the engine, so that the supercharger shaft lies co-axially or parallel with the crankshaft.

Flow Characteristics of a Novel Centrifugal Compressor Design

2016 ◽  
Author(s):  
Shashank Mishra ◽  
Shaaban Abdallah ◽  
Mark Turner
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Axial Compressor ◽  
Low Pressure ◽  
Flow Path ◽  
Optimization Techniques ◽  
Single Stage ◽  
Multi Stage ◽  
Compressor Design

Multistage axial compressor has an advantage of lower stage loading as compared to a single stage. Several stages with low pressure ratio are linked together which allows for multiplication of pressure to generate high pressure ratio in an axial compressor. Since each stage has low pressure ratio they operate at a higher efficiency and the efficiency of multi-stage axial compressor as a whole is very high. Although, single stage centrifugal compressor has higher pressure ratio compared with an axial compressor but multistage centrifugal compressors are not as efficient because the flow has to be turned from radial at outlet to axial at inlet for each stage. The present study explores the advantages of extending the axial compressor efficient flow path that consist of rotor stator stages to the centrifugal compressor stage. In this invention, two rotating rows of blades are mounted on the same impeller disk, separated by a stator blade row attached to the casing. A certain amount of turning can be achieved through a single stage centrifugal compressor before flow starts separating, thus dividing it into multiple stages would be advantageous as it would allow for more flow turning. Also the individual stage now operate with low pressure ratio and high efficiency resulting into an overall increase in pressure ratio and efficiency. The baseline is derived from the NASA low speed centrifugal compressor design which is a 55 degree backward swept impeller. Flow characteristics of the novel multistage design are compared with a single stage centrifugal compressor. The flow path of the baseline and multi-stage compressor are created using 3DBGB tool and DAKOTA is used to optimize the performance of baseline as well novel design. The optimization techniques used are Genetic algorithm followed by Numerical Gradient method. The optimization resulted into improvements in incidence and geometry which significantly improved the performance over baseline compressor design. The multistage compressor is more efficient with a higher pressure ratio compared with the base line design for the same work input and initial conditions.

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