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Gastric carcinoma is a frequent malignant tumor worldwide. NM23 plays an important role in pathological processes, including in the occurrence and development of tumors. The purpose of this study is to examine the effect of NM23 transfection of human gastric carcinoma cells (BGC-823) on growth and metastases of BGC-823 abdominal cancer xenografts in nude mice. BGC-823 cells were transfected with an adenovirus vector for NM23 (NM23-OE), transfected with an empty vector (NC), or were not transfected (Ctrl). Eighteen female BALB/c-nu mice were randomly divided into three groups (six per group) according to the type of BGC-823 cells administered by intraperitoneal injection. After 2 weeks, necropsies of mice were performed, abdominal circumferences were measured, and abdominal cavities were searched by ultrasound. In order to observe the xenografts in nude mice, there were gross macroscopic observations and microscopic observations. In addition, immunohistochemical analysis and western blot of NM23 were also performed. Green fluorescence in the NM23-OE and NC cells indicated successful transfection. The multiplicity of infection is 80%. A comparison of the three groups of mice indicated the NM23-OE group had positive conditions (abdominal circumferences: 81.83 ± 2.40 mm), but the other groups had negative conditions and enlarged abdomens (NC: 90.83 ± 2.32 mm; Ctrl: 92.67 ± 2.07 mm). Ultrasound observations confirmed large tumors in the NC and Ctrl groups, but did not find in the NM23-OE group. There were no obvious ascites in the NM23-OE group, but the cytological examination of ascites exfoliation in NC and Ctrl groups indicated that there were large and deep-stained gastric carcinoma cells. Tumor expression of NM23 was greater in the NM23-OE group than in the NC and Ctrl groups (both p < 0.05). In conclusion, transfection of BCG-823 cells with NM23 rather than an empty vector (NC) or no vector (Ctrl) led to reduced growth and metastases of abdominal cancer xenografts in nude mice.

A novel spiro-type donor 5H-spiro[benzo[b]acridine-12,9′-fluorene] and a thermally activated delayed fluorescence emitter bis(4-(5H-spiro[benzo[b]acridine-12,9′-fluoren]-5-yl)phenyl)methanone were synthesized for a high efficiency organic light-emitting diode.

Aircraft electrification has become a tendency with demands for low carbon emissions and high electrical load capacity nowadays. Aircraft are especially strict with onboard weight; as a result, high-temperature superconducting (HTS) electrical machines are drawing attention for airborne applications due to their potential for a significant increase in power density. In this study, a feasible scheme of a hybrid-HTS airborne synchronous generator was proposed to fulfill the requirements of a small aircraft (with fewer than eight seats and a maximum range of about 1000 km). The full design from top to bottom is described. The output characteristics and metallic and superconducting AC losses were calculated based on the finite element method. The power grade of 1 MW was obtained, with a power density of 9.27 kW/kg and an efficiency of 98.73%. Furthermore, the performance of the machine was optimized using the Taguchi method. The preliminary design demonstrated the possibility and benefits of hybrid-HTS machines for airborne applications.

High-temperature superconductor (HTS) machine is a promising candidate for the electrical aircraft propulsion due to its great advantage in high power density. However, the HTS machine always suffers the problem of low thermal stability during quench. In this article, we apply a no-insulation (NI) coil technique on the rotor windings of HTS machines to enhance the stability and safety of the electrical aircraft. The NI HTS rotor windings experience ripple magnetic fields, which leads to induced eddy currents through turn-to-turn contacts. This induced current and accompanying losses will considerably affect the practicality of this technique. To study this issue, an equivalent circuit network model is developed, and it is validated by experiments. Then, analysis using this model shows that most of induced current flows in the outermost turns of the NI HTS coil because of skin effect, and lower turn-to-turn resistivity leads to higher transport current induced and more significant accumulation of turn-to-turn loss. A grading turn-to-turn resistivity is proposed to reduce the transport current induced and ac loss accumulation and meanwhile keep the high thermal stability of the NI HTS coil. Optimization of turn-to-turn resistivity is required when the NI HTS coil is applied in the machines' environments.

Chemical solution deposition is a promising technology to fabricate YBCO superconducting thin films due to its low-cost advantage. However, the decreasing of critical current density ( J c ) usually occurred in the fabrication of multi-layered YBCO films. In this study, Ag and Au heterogeneous interlayers were fabricated by using sputtering deposition in order to improve the bi-layered YBCO films, and the influence of crystallization temperature from 740 ∘C to 800 ∘C was investigated. It was found that J c could be enhanced by both interlayers relative to the counterparts without interlayers, and the effect of Ag interlayer was superior to that of Au interlayer. When the crystallization temperature was 800 ∘C, the optimal sample with Ag interlayer had a J c 3.65 MA/cm2, which was about twice of the J c of its counterpart. The surface morphologies and cross-sections were observed by using scanning electron microscope, and the content variations of c-axis oriented grains were measured by using Raman spectroscopy, which could help to investigate the influences of interlayers on the microstructure of YBCO films. The possible reasons for the improvement effects of Ag and Au interlayers were discussed based on the experimental results.

Porous graphene materials show outstanding performance in energy storage field due to their unique microstructure and properties. To construct 3D hierarchical porous graphene and combine with conductive polyaniline is an effective way to realize high energy density and good cycling stability. The interlamellar macroporous structure of 3D graphene was constructed by polystyrene (PS) microspheres and nickel foam as double templates. The mesoporous structure was etched in 3D macroporous graphene sheets by potassium hydroxide (KOH) chemical activation. And 3D hierarchical porous graphene (3D-hpGr) composited with polyaniline (PANI) by in situ chemical oxidative polymerization to obtain 3D-hpGr/PANI composites. The effect of the introduction of 3D-hpGr on microstructure, morphology and electrochemical performance of the composites was investigated. PANI nanowire arrays successfully decorate the surface of the 3D-hpGr sheets when the amount of 3D-hpGr reaches 40% (wt%). The specific capacitance of 3D-hpGr/PANI40 reaches 573 F g−1 at 0.5 A g−1, much higher than that of pure PANI (419 F g−1). The retention ratio of 3D-hpGr/PANI40 retains 84% of its initial specific capacitance after 1000 cycles at 1.0 A g−1, and the cycling stability of all composites is higher than that of pure PANI (69%). The potential drop of 3D-hpGr/PANI composites decreases from 0.339 V to 0.139 V, and the energy density increases consequently. The energy density of 3D-hpGr/PANI40 reaches 31.2 W h kg−1 at the power density of 0.709 kW kg−1.

The need for energy is growing as civilization develops. Superconductors have various benefits over regular conductors, including a high current-carrying density and nearly no resistance. Therefore, the objective that scientists continue to seek is the use of superconductors to replace traditional conductors in order to satisfy the demand for energy. As a key part of the superconducting electrical system, the critical current is one of the key properties of high-temperature superconducting (HTS) coils. Scholars have created a variety of numerical simulation models to estimate the performance of HTS coils. However, the extremely nonlinear E–J power law relationship that characterizes the voltage–current relationship in superconducting materials necessitates numerous iterative refinements during the coil design stage, which is time-consuming from the perspective of computing efficiency. Consequently, it is essential to increase computational efficiency. In this study, the critical current of HTS coils was calculated using the J model (integral method with the current density J as the state solution variable), and it was proved to be an efficient research method. The accuracy of the method is verified by comparing with the H model and the experimental measurement results of the critical current of the HTS coil. Moreover, compared with the reference finite element simulation model, this model has a speed advantage of at least four times, which is a good choice, especially, for HTS circular coils with large turns.

Inductance is a very commonly used electrical parameter in transient progress analysis, as well as in energy storage evaluations. It was normally considered as constant when the geometrical configuration of a coil is determined. However, experiments on Bi-2223 (Bi 2 Sr 2 Ca 2 Cu 3 O 10+x ) and YBCO (YBa 2 Cu 4 O 7-x ) coils, both show 10% rise inductance while increasing the applied current. The inductance grows approximately a linear relationship from its minimum to maximum. We used both theoretical and experimental analysis to deeply understand the mechanism of the variation in terms of current distribution in high-temperature superconducting (HTS) coils. Taking this inductance change into account would benefit the accuracy in energy storage applications and in transient analysis occasions. Besides, inductance controllable devices could be achieved by manipulating the bias current applied on HTS coils.

Scanning Hall probe (SHP) system is a powerful instrument to investigate the planar distribution of areal critical current density (j c ) and defects of high temperature superconducting (HTS) thin film samples. The distance between the effective measuring position and probe bottom (h 1 ) is usually unknown for the commercialized Hall probes. However, h 1 value has a significant influence on the measurement results, according to the calculation of the magnetic flux density (B 0 ) above the planar center of a rectangular HTS thin film sample. In this paper, a method was proposed to obtain h 1 by using a series of copper strips and analyzing the relationship of B 0 against the parameters, such as sample width and current. Then, SHP system was employed to characterize the j c distribution of an HTS thin film fabricated via chemical solution deposition. The relationship of B 0 and h 1 could also be utilized to obtain the average j c value (j c B0 ). A series of commercialized coated conductor samples were measured with both SHP and the traditional four-probe method. The feasibility of preliminary evaluation for rectangular HTS thin film samples by using j c B0 was discussed based on its correlation with the results of four-probe method.

In this paper, the I c degradation of bent YBCO tapes has been experimentally studied. The I c characteristics in length direction was measured through a non-contact, continuous I c measurement equipment (Mcorder), which is suitable for all kinds of high temperature superconducting (HTS) tapes. The detailed J c mapping of bent tapes was investigated by a Hall microscopy equipment (Mcorder 2-D), which scans the fields distribution on the surface of the films or bulks. A 4.1-m-long YBCO tape was wound on a 4.5-mm-diameter core with YBCO face outside or inside. The critical current of the YBCO tape before and after winding was measured lengthwise. And the 2-D J c map of the samples of degraded sections was measured. The result shows that the smallest safe bending diameter is larger than 14 mm and smaller than 4.5 mm, for YBCO face outside and inside, respectively, which indicates that the YBCO face is recommended to be inside in bending cases. The relation between critical current of YBCO face outside bent tapes and diameters was fitted to a sigmoid-like function, to help further development where YBCO face outside bending is unavoidable.

Superconducting fault current limiters (SFCLs) are attracting increasing attention due to their potential for use in modern smart grids or micro grids. Thanks to the unique non-linear properties of high-temperature-superconducting (HTS) tapes, an SFCL is invisible to the grid with faster response compared to traditional fault current limiters. The quench recovery characteristic of an HTS tape is fundamental for the design of an SFCL. In this work, the quench recovery time of an HTS tape was measured for fault currents of different magnitudes and durations. A global heat transfer model was developed to describe the quench recovery characteristic and compared with experiments to validate its effectiveness. Based on the model, the influence of tape properties on the quench recovery time was discussed, and a safe margin for the impact energy was proposed.

Methylenetetrahydrofolate reductase (MTHFR), an enzyme expressed in mammalian testes, exerts a direct effect on spermatogenesis, however, its protein characteristics in bovine testes remain unknown. Here, we analysed bovine testicular structure, MTHFR bioinformatics profile, mRNA, and protein expression characteristics in yellow-cattle (y-c) and yak testis using histological procedures, bioinformatics analysis, qRT-PCR, and western blot. Testes from 13 bovines, &le, 2 years juvenile (y-c, n = 3, yak, n = 3) and &ge, 3 years adult (y-c, n = 3, yak, n = 4) were collected and analysed. Anatomical characteristics of testis in y-c and yak were similar except the weight or size for which that of y-c was significantly higher or greater than yak. In y-c, an open reading frame (ORF) for 2600 nucleotides sequence, encoding 655 amino acids showed high homology with zebu cattle (99.51%) and wild yak (98.68%). Secondary and 3D protein structures were similar to that of humans with differences in the number of nucleotides, amino acids, and some physico-chemical characteristics. MTHFR mRNA expression in y-c and yak were significantly higher in adult testes compared with juvenile ones. However, its protein expression was higher, but not statistically significant, in adult y-c and yak compared to the juvenile ones. The highlights and inferences of these and other findings are discussed.

Graphene-based composites took extensive attraction as electrodes for supercacitors these years. Three-dimensional cross-linking porous graphene (3D rGO-m) was obtained by KOH activation to graphene modified by 1,2,4-triaminobenzene. 3D porous graphene/ polyaniline hybrids (3D rGO-m/PANI) was prepared by the in-situ chemical oxidative polymerization. The rGO-m are reconstructed from 2D to 3D porous structure after KOH activation. The PANI nanorod arrays are successfully decorated on the surface of the 3D porous graphene sheets. The specific capacitance of the 3D rGO-m/PANI hybrids reach 985 F/g at 0.5 A/g. The capacitance retention of 3D rGO-m/PANI maintains 90% of its initial capacity after 1000 cycles, while rGO-m/PANI only keeps 83% of its initial capacity, the cycling stability of both hybrids are higher than that of pure PANI (69%).

An optimization method of chromogenic agent was mainly studied to detect the concentration of metal ions in zinc metallurgy wastewater based on ultraviolet-visible spectrometry. Firstly, a chromogenic agent was selected to reduce the sensitivity of Zn(II) that solved the problem of spectral masking caused by high concentration of Zn(II). However, the range of noiseless wavelength, linearity of Zn(II) and additivity of absorbance were serious influenced by the dosage of chromogenic agent. So, a multi-objective optimization method with the target of maximum range of noiseless wavelength, maximum linearly dependent coefficient of Zn(II) and the optimum additivity of absorbance was proposed to optimize the dosage of chromogenic agent. Finally, the optimization result are verified by feature interval association-partial least squares regression. The average relative errors of Zn(II), Cu(II), Co(II) and Ni(II) were 5.43%, 6.65%, 6.24% and 6.87%, respectively. It indicates that the detection method using optimal chromogenic agent exhibit high-precision and low-error for analyzing the concentration of Zn(II), Cu(II), Co(II) and Ni(II).

Indoor positioning methods based on the received signal strength indication (RSSI) ranging technology are sensitive to various environmental noises, which cause positioning errors. An improved Wi-Fi indoor positioning method using an improved unscented Kalman filter and the particle swarm optimization (PSO) is proposed to reduce ranging error and improve positioning accuracy. The received signals are preprocessed by the improved unscented Kalman filter algorithm and then the improved PSO algorithm is used to optimize position calculation results. To demonstrate the utility of the proposed algorithm, simulations and experiments were performed for estimating the position of objects. Simulating results indicate that the mean error of the proposed algorithm is reduced by 31.87% in comparison with that of the unlicensed Kalman filter method. Experimental results show that the mean error of the proposed algorithm is reduced by 26.72% in comparison with that of the unlicensed Kalman filter method. Therefore, the proposed algorithm can effectively reduce the positioning error and improve the positioning accuracy. In the actual indoor positioning, it could get better positioning results.

Reducing heat leakage is crucial for the development of practical superconducting devices. In this work, orthogonal experimental design method is first used to optimize the design of hundred-ampere and kiloampere Peltier current leads (PCLs). Geometry and arrangement of Peltier materials and conductive materials of the current lead are analyzed. Through our simulation, we find that the coupling effect between the radius of Bi2Te3 (r2) and the length of Bi2Te3 (L2) has the greatest effect on the heat leakage of PCLs at the cold end for both PCLs. Furthermore, numerical simulations suggest that the lowest heat leakage at the cold end (approximately 30.0 W/kA) is at the same level for both hundred-ampere and kiloampere PCLs. If taking the heat dissipation area at the hot end into account, multiterminal solutions are better solutions for kiloampere current leads.

A novel surface-mounted permanent-magnet synchronous motors (SPMSMS) for the sensorless control strategy is proposed in this paper. The proposed topology is detecting asymmetric inductance of motor to identify the rotor position and can be derived in the range of high speed and low speed with the high and reliable commutation accuracy. Another attractive feature is that different from the traditional sensorless control strategy, this strategy can detect the information of the rotor position in the whole mechanical cycle. In the end, the performance has been verified via simulation.

High-temperature superconducting (HTS) bulks can be magnetized to become powerful trapped field magnets (TFMs), which are promising for high-performance electrical applications. To magnetize such TFMs, pulsed field magnetization (PFM) is supposed to substitute field cooling (FC) to provide in situ magnetization. However, the heat generation during PFM, which reduces the trapped field, has always been an issue; thus, numerical simulation of the process is important to provide optimal magnetization strategies. In this paper, HTS bulks magnetized by PFM are simulated with an axisymmetric electromagnetic-thermal coupled model based on the H-formulation. Influences of important yet difficult-to-characterize parameters of HTS bulks, including n values in the E-J power law and B 0 in the Kim model, are investigated to show the influences of parameters on the modeling of HTS by PFM.

In transient operations or fault conditions, high-temperature superconducting (HTS) machines suffer ac losses, which have an influence on the thermal stability of superconducting windings. In this paper, a method to calculate ac losses and their thermal effect in HTS machines is presented. The method consists of three submodels that are coupled only in one direction. The magnetic field distribution is first solved in a machine model, assuming a uniform current distribution in HTS windings. The magnetic fields on the boundaries are then used as inputs for an ac loss model that has a homogeneous approximation and solves the H formulation. Afterward, the computed ac losses are considered as the heat source in a thermal model to study the temperature profile in HTS windings. The method proposed is able to evaluate ac losses and their thermal effect, thus providing a reference to design an HTS machine and its cooling system.

High temperature superconducting (HTS) stacks of coated conductors (CCs) can work as strong trapped field magnets (TFMs) and show potential in electrical applications. Pulsed field magnetization (PFM) is a practical method to magnetize such TFMs, but due to heat generation during the dynamic process, it cannot achieve a trapped field as high as field cooling can. In this work, we construct a 2D electromagnetic-thermal coupled model to simulate stacks of HTS CCs with realistic laminated structures magnetized by PFM. The model considers temperature and anisotropic magnetic field dependent Jc of HTS and other temperature dependent thermal and electrical material properties. Based on the model, a configuration of controlled magnetic density distribution coils is suggested to improve the trapped field compared to that obtained by ordinary solenoids.

Over the past few years, supercapacitors based on graphene/polyaniline (rGO/PANI) composites have gained immense attention. The electrochemical performance of rGO/PANI composites can be improved by controlling their morphology and structure. However, very few studies have been carried out on amine-functionalized graphene/polyaniline (F-rGO/PANI) composites. In this study, amine-functionalized graphene (F-rGO) and mesoporous graphene (PF-rGO) were composited with PANI. The results showed that the specific capacitance of the F-rGO/PANI composites could be improved by controlling their morphology. The mesoporous structure of F-rGO contributed to the improvement in the cycling stability and energy density of the composites. At a current density of 0.5 A g−1, the specific capacitances of F-rGO/PANI20–0.5h and PF-rGO/PANI are 597 F g−1 and 489 F g−1, respectively; these values are remarkably higher than that of pure PANI (400 F g−1). F-rGO/PANI20-0.5th and PF-rGO/PANI maintained specific capacitances of 75% and 89%, respectively, which were significantly higher than that of pure PANI; this was observed even after 2000 cycles of charge and discharge had been completed at a current density of 1 A g−1. The energy density of PF-rGO/PANI reaches 34.9 W h kg−1 at the power density of 1.27 kW kg−1. This study is expected to provide an effective basis for the future research of graphene-based composite electrode materials for supercapacitors.

HSP70/90 play important role in testis develop and spermatozoa regulation, but the contact of HSP70/90 with infertility in cattle is unclear. Here, we focus on male cattle-yak and yak, which to investigate the expression and localization of HSP70/90 in different tissues, and explore the influence of HSP70/90 to infertility. In our study, a total of 54 cattle (24 cattle-yak and 30 yak) were examined. The HSP90 mRNA of cattle-yak was cloned first and found amino acid variation in HSP90, which led to difference at protein spatial structure compare with yak. To investigate whether the expression of HSP70/90 mRNA and protein are different in cattle-yak and yak, we used real-time quantitative PCR (qRT-PCR) and Western blot (WB) to examine them. We found that the expression level of HSP70/90 mRNA and protein are disparity in different tissues and testis development stages, and obviously high expression was observed in testicle during juvenile and adult, Moreover, it‘s interestingly in which the HSP70 expression is significant high in yak whereas HSP90 in cattle-yak (P

The magnetic circuit (MC) method has been developed to measure the critical current (I c ) of long high temperature superconductor (HTS) tapes continuously since 2010. So far, with the apparatus based on the MC method, namely MCorder, industrial HTS tapes produced by main manufactures worldwide have been measured using the MC method, including Bi2223/Ag multifilament tapes and coated conductors with/without magnetic substrates. The high speed (360 m/h), high accuracy measurement (resolution 1 A) and its adaption to all kinds of HTS tapes make large quantity measurement and statistical evaluation of HTS tape possible. In this paper, criteria for I c assessment of long HTS tapes is discussed, based on which analysis of samples from different manufacturers worldwide is provided. The measurement result of a Bi2223/Ag tape by MC method is compared with section-by-section four-probe method, and the two methods show good agreement. Fourier analysis is given for analyzing I c periodicity of a tape with periodical artificial defects.

In recent years, numerical models have become popular and powerful tools to investigate the electromagnetic behavior of superconductors. One domain where this advances are most necessary is the 3D modeling of the electromagnetic behavior of superconductors. For this purpose, a benchmark problem consisting of superconducting cube subjected to an AC magnetic field perpendicular to one of its faces has been recently defined and successfully solved. In this work, a situation more relevant for applications is investigated: a superconducting parallelepiped bulk with the magnetic field parallel to two of its faces and making an angle with the other one without and with a further constraint on the possible directions of the current. The latter constraint can be used to model the magnetization of a stack of high-temperature superconductor tapes, which are electrically insulated in one direction. For the present study three different numerical approaches are used: the Minimum Electro-Magnetic Entropy Production (MEMEP) method, the $H$-formulation of Maxwell's equations and the Volume Integral Method (VIM) for 3D eddy currents computation. The results in terms of current density profiles and energy dissipation are compared, and the differences in the two situations of unconstrained and constrained current flow are pointed out. In addition, various technical issues related to the 3D modeling of superconductors are discussed and information about the computational effort required by each model is provided. This works constitutes a concrete result of the collaborative effort taking place within the HTS numerical modeling community and will hopefully serve as a stepping stone for future joint investigations.

High temperature superconducting (HTS) bulks or stacks of coated conductors (CCs) can be magnetized to become trapped field magnets (TFMs). The magnetic fields of such TFMs can break the limitation of conventional magnets (

A new method based on the principle of magnetic circuits is proposed and realized for continuous Ic examination of HTS tapes. The greatest advantages of the new method are that it first eliminates all the noise caused by mechanical fluctuations, and thus makes high speed and high stability measurement possible, and second has a natural ability to measure HTS tape with a magnetic substrate. The principle of the method is introduced with the help of Finite Element Analysis. An apparatus for examination of kilometer long tapes has been constructed, by which continuous Ic examination for a YBa2Cu3O7-x tape with and without a magnetic substrate and a Bi2Si2Ca2Cu3Ox multi-filamentary tape is reported.

The critical current (I(c)) of high-temperature superconductor (HTS) tapes has to be examined not only for short samples, but also for the entire tape, because local weak points can possibly lead to the quenching of the whole HTS device. Some methods were reported for continuous I(c) measurement along the length of a HTS tape, but few of them were applicable to tapes with magnetic substrates represented by YBa2Cu3O(7-δ)(YBCO)-coated conductors based on Ni5W alloy substrate by rolling assisted bi-axially textured substrate process. We previously presented a contact-free method using magnetic circuits to measure I(c) continuously of long HTS tapes, namely the magnetic-circuit (MC) method. This method has been previously applied with high speed and resolution to measure I(c) of HTS tapes with non-magnetic substrates, due to its resistance to noise aroused by mechanical vibration. In this work, its ability to measure HTS tapes with magnetic substrates is demonstrated both theoretically and experimentally. A 100 m long commercial YBCO tape based on Ni5W alloy substrate was measured and regular I(c) fluctuations were discovered. The MC method can be a powerful tool for quality control of HTS tapes, especially for tapes with magnetic substrates.

A method based on the principle of the magnetic circuit is proposed and realized for contactless measurement of critical current (I(c)) of high temperature superconductor tapes. This method has two unique features: first, it eliminates noises caused by mechanical fluctuations and thus makes high speed and high stability measurement possible and second, adapts for both Bi(2)Si(2)Ca(2)Cu(3)O(x) (Bi2223) and YBa(2)Cu(3)O(7-x) (YBCO) tape, which even has a magnetic substrate. Theoretical analysis is given and an apparatus for the reel-to-reel measurement has been constructed, by which continuous inspection of I(c) uniformity of YBCO and Bi2223 tapes measured at different speeds is reported.

A passive magnetic field cancellation device (PMFCD) is designed. The PMFCD could automatically cancel the field as an active cancellation system did; however it requires no power sources and feedback systems. The capability of the PMFCD is based on the principle that a closed loop can resist flux variation and keep the flux constant inside. The closed loop in the PMFCD is formed by connecting two pairs of high temperature superconductor Helmholtz coils with different radii in series. More important thing is that the ratio of the radius and the turn number between the coils has to satisfy a number of conditions, with which 100% cancellation can be reached. Theoretical methods to obtain the turn number ratio and radius ratio are the major part of the paper. Numerical simulation was followed, aiming to evaluate field distribution under a cancellation state and correct the theoretical values.

In this study, three armature structures for a fully HTS synchronous generators were proposed. The total ac loss of the straight segments of entire armature coils was studied. The ac loss was calculated in a 2-D infinite long model by using H-formulation considering Jc-B characteristics. The proposed armature windings can be simplified to a two-slot structure for ac loss calculation due to symmetry. AC transport current and the maximum and minimum external ac fields were applied to calculate the ac loss limits for one coil cross section in each model. The proportion of the cooling power for compensating the heat generated by ac loss in the output power under a 30-A peak transport current was estimated for the proposed three structures.