scholarly journals Experimental and Simulation Research of AC Ripple Losses in a High Temperature Superconductor Tape

2018 ◽  
Vol 2018 ◽  
pp. 1-5
Author(s):  
Hongwei Liu ◽  
Guosheng Song ◽  
Chuanhui Zhang ◽  
Jinwen Tan ◽  
Wengang Feng
Keyword(s):  
Superconducting Magnets ◽  
Ac Loss ◽  
Ac Losses ◽  
Strong Impact ◽  
Simulation Research ◽  
Current Transmission ◽  
Current Leads ◽  
The Stability ◽  
Superconductor Tape ◽  
Operation Cost

Current leads in superconducting magnets are widely adopted for heavy current transmission, and HTS DC cables have great advantages when used as current leads for such purposes. However, as an important parameter of HTS DC cables, AC loss has a strong impact on the stability and operation cost of current leads. In this paper, experiments were conducted to measure AC ripple losses of HTS tapes and HTS cables, and simulations of HTS tapes were carried out. The paper has reached conclusions on the relation between AC losses and power frequencies.

scholarly journals AC losses of no-insulation high temperature superconductor (RE)Ba2Cu3Ox coils induced by ripple magnetic fields in machines

2020 ◽  
Author(s):  
Yawei Wang
Keyword(s):  
High Temperature ◽  
Magnetic Fields ◽  
High Temperature Superconductor ◽  
Eddy Currents ◽  
Ac Loss ◽  
Ac Losses ◽  
Induced Current ◽  
Risk Optimization ◽  
Current Flows ◽  
The Stability

<p>No-insulation high temperature superconductor (NI HTS) (RE)Ba2Cu3Ox coil technology is effective in enhancing the thermal stability of HTS coils. Applying the NI technique on the rotor windings of HTS machines can improve the stability and reliability of the machines. However, the NI HTS rotor windings experience ripple magnetic fields, which leads to induced eddy currents through the turn-to-turn contacts. The accompanying turn-to-turn losses will considerably affect the machine efficiency. In this study, we compared experimentally the losses of NI HTS coils subjected to external AC magnetic fields with those of insulated coils. Measurement system based on calibration-free method is developed for the AC loss measurement on HTS coils exposed to external AC magnetic fields. The results show that the AC loss of NI HTS coils can be 20 times higher than that of insulated HTS coils, and lowering turn-to-turn resistivity can significantly reduce this AC loss. Modeling analysis shows that most of induced current flows in the outer turns of the NI HTS coil because of skin effect, and lower turn-to-turn resistivity leads to higher induced current in superconducting layers and more significant accumulation of turn-to-turn loss. This will increase quench risk. Optimization of turn-to-turn resistivity is required when the NI HTS coil is applied in the machines environments. </p>

scholarly journals AC losses of no-insulation high temperature superconductor (RE)Ba2Cu3Ox coils induced by ripple magnetic fields in machines

2020 ◽  
Author(s):  
Yawei Wang
Keyword(s):  
High Temperature ◽  
Magnetic Fields ◽  
High Temperature Superconductor ◽  
Eddy Currents ◽  
Ac Loss ◽  
Ac Losses ◽  
Induced Current ◽  
Risk Optimization ◽  
Current Flows ◽  
The Stability

<p>No-insulation high temperature superconductor (NI HTS) (RE)Ba2Cu3Ox coil technology is effective in enhancing the thermal stability of HTS coils. Applying the NI technique on the rotor windings of HTS machines can improve the stability and reliability of the machines. However, the NI HTS rotor windings experience ripple magnetic fields, which leads to induced eddy currents through the turn-to-turn contacts. The accompanying turn-to-turn losses will considerably affect the machine efficiency. In this study, we compared experimentally the losses of NI HTS coils subjected to external AC magnetic fields with those of insulated coils. Measurement system based on calibration-free method is developed for the AC loss measurement on HTS coils exposed to external AC magnetic fields. The results show that the AC loss of NI HTS coils can be 20 times higher than that of insulated HTS coils, and lowering turn-to-turn resistivity can significantly reduce this AC loss. Modeling analysis shows that most of induced current flows in the outer turns of the NI HTS coil because of skin effect, and lower turn-to-turn resistivity leads to higher induced current in superconducting layers and more significant accumulation of turn-to-turn loss. This will increase quench risk. Optimization of turn-to-turn resistivity is required when the NI HTS coil is applied in the machines environments. </p>

scholarly journals The Effect of pH and Storage Temperature on the Stability of Emulsions Stabilized by Rapeseed Proteins

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1657
Author(s):  
Karolina Östbring ◽  
María Matos ◽  
Ali Marefati ◽  
Cecilia Ahlström ◽  
Gemma Gutiérrez
Keyword(s):  
Zeta Potential ◽  
Storage Temperature ◽  
Emulsion Stability ◽  
Press Cake ◽  
Strong Impact ◽  
Soy Lecithin ◽  
Rapeseed Protein ◽  
Rapeseed Proteins ◽  
Precipitation Ph ◽  
The Stability

Rapeseed press cake (RPC), the by-product of rapeseed oil production, contains proteins with emulsifying properties, which can be used in food applications. Proteins from industrially produced RPC were extracted at pH 10.5 and precipitated at pH 3 (RPP3) and 6.5 (RPP6.5). Emulsions were formulated at three different pHs (pH 3, 4.5, and 6) with soy lecithin as control, and were stored for six months at either 4 °C or 30 °C. Zeta potential and droplet size distribution were analyzed prior to incubation, and emulsion stability was assessed over time by a Turbiscan instrument. Soy lecithin had significantly larger zeta potential (−49 mV to 66 mV) than rapeseed protein (−19 mV to 20 mV). Rapeseed protein stabilized emulsions with smaller droplets at pH close to neutral, whereas soy lecithin was more efficient at lower pHs. Emulsions stabilized by rapeseed protein had higher stability during storage compared to emulsions prepared by soy lecithin. Precipitation pH during the protein extraction process had a strong impact on the emulsion stability. RPP3 stabilized emulsions with higher stability in pHs close to neutral, whereas the opposite was found for RPP6.5, which stabilized more stable emulsions in acidic conditions. Rapeseed proteins recovered from cold-pressed RPC could be a suitable natural emulsifier and precipitation pH can be used to monitor the stability in emulsions with different pHs.

Experimental and Molecular Simulation Research on the Effect of Metal Ions on the Stability of SDS Foam

2021 ◽  
Author(s):  
Zhiyu Dong ◽  
Shuo Liu ◽  
Xin Nie ◽  
Yulong Zhang ◽  
Kaili Dong ◽  
...  
Keyword(s):  
Metal Ions ◽  
Molecular Simulation ◽  
Simulation Research ◽  
The Stability

Contact resistance, coupling and hysteresis loss measurements of ITER Poloidal Field joint in parallel applied magnetic field

2021 ◽  
Author(s):  
Jianfeng Huang ◽  
Y. Ilyin ◽  
W.A.J. Wessel ◽  
Ruben Lubkemann ◽  
Erik Krooshoop ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Contact Resistance ◽  
Applied Magnetic Field ◽  
Applied Field ◽  
Simulated Data ◽  
Hysteresis Loss ◽  
Ac Loss ◽  
Field Conditions ◽  
Ac Losses ◽  
First Time

Abstract The inter-strand contact resistance and AC losses were measured on an ITER PF Coil joint in a parallel applied AC magnetic field. In addition, the hysteresis loss was measured as a function of the angle with the applied magnetic field on a NbTi strand of the same type as in the joint with a Vibrating Sample Magnetometer (VSM). The AC loss measurements were performed at four applied field conditions for combinations of 0 or 1 T offset field and 0.2 or 0.4 T sinusoidal amplitude. The hysteresis loss of the joint was compared with the measured AC loss density of the NbTi strand for the same field conditions as the joint AC loss measurement but with varying the angle of the applied field. The subsequent cable twist angles affect the hysteresis loss since the critical current and penetration field depend on the angle of the applied field. It is found that 15.5° is an effective angle for the calculation of the hysteresis loss of joint when compared to the single strand measurement. The inter-strand contact resistance measurements cover all the typical strand combinations from the five cabling stages of the individual conductors, as well as the strand combinations across the two conductors to characterize the inter-strand including the copper sole resistivity. It’s the first time to measure the contact resistances and AC losses of the full-size ITER PF joint. By comparing the measured and simulated data in the JackPot-ACDC model, it’s also the first time to obtain the accurate inter-strand, inter-petal and strand to copper sole contact resistivities, which are the main input parameters for the further quantitative numerical analysis of the PF joints, in any current and magnetic field conditions.

scholarly journals The effect of consolidated periods in heterogeneous lot-sizing games

Top ◽  
2021 ◽  
Author(s):  
Luis A. Guardiola ◽  
Ana Meca ◽  
Justo Puerto
Keyword(s):  
Time Horizon ◽  
Lot Sizing ◽  
Sufficient Conditions ◽  
Minimum Cost ◽  
Cost Allocations ◽  
Lot Sizing Problem ◽  
Stable Family ◽  
Finite Time Horizon ◽  
The Stability ◽  
Operation Cost

AbstractWe consider a cooperative game defined by an economic lot-sizing problem with heterogeneous costs over a finite time horizon, in which each firm faces demand for a single product in each period and coalitions can pool orders. The model of cooperation works as follows: ordering channels and holding and backlogging technologies are shared among the members of the coalitions. This implies that each firm uses the best ordering channel and holding technology provided by the participants in the consortium. That is, they produce, hold inventory, pay backlogged demand and make orders at the minimum cost of the coalition members. Thus, firms aim at satisfying their demand over the planing horizon with minimal operation cost. Our contribution is to show that there exist fair allocations of the overall operation cost among the firms so that no group of agents profit from leaving the consortium. Then we propose a parametric family of cost allocations and provide sufficient conditions for this to be a stable family against coalitional defections of firms. Finally, we focus on those periods of the time horizon that are consolidated and we analyze their effect on the stability of cost allocations.

scholarly journals Flexible Tranmission Elements for Grid Optimization

2021 ◽  
Vol 21 (2) ◽  
pp. 53-61
Keyword(s):  
Power Systems ◽  
Electric Power ◽  
Emergency Operation ◽  
Power Losses ◽  
Current Transmission ◽  
Before And After ◽  
Grid Optimization ◽  
Flexible Alternating Current Transmission ◽  
Active Power Losses ◽  
The Stability

The article dwells upon optimizing, reduction of losses in, and improving the stability of grids by implementing devices that affect the parameters and power flows in a grid. State-of-the-art technology for better control is crucial for the development of electric power systems. FACTS technologies or flexible alternating current transmission systems, essentially transform the grid from a passive electricity transport into a device that actively controls the grid parameters. The article analyzes the development of a 500/220/110 kV grid that uses parameter-affective devices: SVC, BSK, LCD. Steady-state parameters, active power losses, and electric power losses were calculated for a year before and after the devices were deployed. Each device was therefore analyzed for effectiveness. The parameters of the SVC-equipped 500/220/110 kV grid were calculated for emergency operation with the 500 kV line being offline. Thus, the paper also analyzes the emergency performance of the SVC.

Actively Cooled Current Leads for Superconducting Electronics Using Mixed-Gas Joule-Thomson Refrigeration

2004 ◽  
Author(s):  
Gregory F. Nellis ◽  
John M. Pfotenhauer ◽  
Sanford A. Klein
Keyword(s):  
Superconducting Magnets ◽  
Pure Substance ◽  
Genetic Optimization ◽  
Mixed Gas ◽  
Thermal Generation ◽  
Reliable Technique ◽  
Temperature Range ◽  
Current Leads ◽  
Gas Cooling ◽  
Materials Used

Electrical leads used for the supply of current to superconducting magnets and electronics must span the temperature range from room temperature to cryogenic temperatures. Because the conventional materials used for such purposes (e.g., copper and aluminum) have both a finite electrical resistance and a significant thermal conductivity, operation of the leads results in both thermal generation and conductance. The resulting thermal loads must be removed from the cryogenic environment. This paper describes a method for integrating cryogenic refrigeration technology with current leads in an efficient and practical manner. The key to this concept is the use of a mixed-gas cooling cycle that absorbs the distributed refrigeration load continuously over the temperature range that it is generated, as opposed to allowing it to pass down to the cold end of the lead where the same energy flow constitutes a much higher entropy load on the cryocooler. Additional benefits of this technology include a more isothermal electronic package, as well as improvements in reliability, and reduction in size and mass. Mixed-gas working fluids can be used within Joule-Thomson devices to achieve a greater refrigeration effect for the same pressure span than is possible with a pure substance. This paper describes a computational tool that allows the composition of gas mixtures to be optimized for the case where the refrigeration load is not completely concentrated at the cold end, as is typically the case, but rather the refrigeration load is distributed over the entire temperature range. A genetic optimization algorithm was found to be the most robust and reliable technique for identifying optimum gas mixture composition. The thermodynamic advantage associated with accepting the refrigeration load at the temperature of its origin, rather than at the cold end, is quantified.

Modeling and Dynamic Research of the Pneumatic-Hydraulic Loading Simulator System

2014 ◽  
Vol 472 ◽  
pp. 8-12 ◽  
Author(s):  
Hong Yan Wang ◽  
Jin Bo Lu ◽  
Xing Dai ◽  
Rong Wang
Keyword(s):  
Simulation Research ◽  
Hydraulic Loading ◽  
Dynamical Simulation ◽  
The Stability ◽  
Dynamic Research

This paper presents the Pneumatic-Hydraulic Loading Simulator System, which structure is new in loading simulator systems. The design of this system takes into account that the gas has greater compressibility, which can effectively reduce the extraneous torque of loading simulator, and the liquid can provide the appropriate damping, which can improve the stability and precision of system. The model of the system is established in this paper, and to make sure that the structure of the system is realizable, the dynamical simulation research is carried out.

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