Pub Date : 2018-04-23DOI: 10.1109/INTMAG.2018.8508833
M. Lostun, D. Herea, M. Grigoraș, G. Ababei, I. Ghemes, N. Lupu
Fe-oxide nanoparticles are of considerable interest nowadays because of their unique characteristics, such as superparamagnetism, high saturation fields, and extra anisotropy contributions, which arise from the effects of finite size and large surface area. Usually they are obtained by chemical methods, but more recently some groups reported on their successful preparation by wet high-energy ball-milling. It is also well known that as the size of the nanoparticles decreases, surface effects would become more significant due to the increasing surface relative to their volume. We report here our recent results on the effect of ligands on the induced surface anisotropies and magnetic properties of Fe/Fe2O3 and Fe/Fe3O4 core-shell nanoparticles functionalized with 3-aminopropyltriethoxysilane (APTS) for biomedical applications (image contrast agents in magnetic resonance imaging (MRI) and magnetic carriers for drug delivery). Core-shell nanoparticles have been prepared by high-energy ball milling. In the presence of air or Ar, the Fe core was progressively covered with a Fe2O3 shell, and the obtained Fe/ Fe2O3 nanoparticles have diameters of 200–300 nm after 68 h of milling. Fe/ Fe3O4 nanoparticles of 20–60 nm were obtained by wet milling of Fe microparticles for 42 h. For milling times larger than 42 h the whole amount of Fe is transformed into Fe3O4, and the resulting magnetite nanoparticles have diameters ranging from 15 to 50 nm (Fig. 1). The magnetic properties of Fe/ FexOy core-shell nanoparticles can be tailored from ferromagnetic Fe/Fe2O3 to weak ferromagnetic Fe/Fe3O4 and superparamagnetic Fe3O4 (Fig. 2). By choosing the appropriate milling conditions and starting materials is possible to tune the magnetic properties and make the Fe/FeOx core-shell NPs suitable for different biomedical applications. The main advantage of such coreshell nanoparticles in biomedical applications, compared with simple Fe-oxides nanoparticles, resides in their easier use and manipulation for specific applications. To understand the surface spin disorder and its influence on the magnetic properties of Fe/Fe-oxide core-shell nanoparticles, their surface was systematically modified with APTS, by increasing progressively the concentration of the ligand. APTS was chosen as ligand because the bonding with the magnetic NPs is made through Si-O, NH2 remaining free for bonding with different types of biomolecules. Low temperature magnetization measurements and ZFC/FC curves indicate a strong influence of the ligand on the magnetic properties. The change of the magnetic properties of nanoparticles also correlates with the specific coordinating functional group bound on the nanoparticles surface. The correlation suggests the decrease in spin-orbital coupling and surface anisotropy of magnetic nanoparticles due to the surface coordination. Because of the high saturation magnetization, these Fe/FeOx core-shell NPs have a higher Specific Absorption Rate (SAR), making them suit
{"title":"The effect of surface spin disorder on magnetic properties of Fe/FexOy core-shell nanoparticles","authors":"M. Lostun, D. Herea, M. Grigoraș, G. Ababei, I. Ghemes, N. Lupu","doi":"10.1109/INTMAG.2018.8508833","DOIUrl":"https://doi.org/10.1109/INTMAG.2018.8508833","url":null,"abstract":"Fe-oxide nanoparticles are of considerable interest nowadays because of their unique characteristics, such as superparamagnetism, high saturation fields, and extra anisotropy contributions, which arise from the effects of finite size and large surface area. Usually they are obtained by chemical methods, but more recently some groups reported on their successful preparation by wet high-energy ball-milling. It is also well known that as the size of the nanoparticles decreases, surface effects would become more significant due to the increasing surface relative to their volume. We report here our recent results on the effect of ligands on the induced surface anisotropies and magnetic properties of Fe/Fe2O3 and Fe/Fe3O4 core-shell nanoparticles functionalized with 3-aminopropyltriethoxysilane (APTS) for biomedical applications (image contrast agents in magnetic resonance imaging (MRI) and magnetic carriers for drug delivery). Core-shell nanoparticles have been prepared by high-energy ball milling. In the presence of air or Ar, the Fe core was progressively covered with a Fe2O3 shell, and the obtained Fe/ Fe2O3 nanoparticles have diameters of 200–300 nm after 68 h of milling. Fe/ Fe3O4 nanoparticles of 20–60 nm were obtained by wet milling of Fe microparticles for 42 h. For milling times larger than 42 h the whole amount of Fe is transformed into Fe3O4, and the resulting magnetite nanoparticles have diameters ranging from 15 to 50 nm (Fig. 1). The magnetic properties of Fe/ FexOy core-shell nanoparticles can be tailored from ferromagnetic Fe/Fe2O3 to weak ferromagnetic Fe/Fe3O4 and superparamagnetic Fe3O4 (Fig. 2). By choosing the appropriate milling conditions and starting materials is possible to tune the magnetic properties and make the Fe/FeOx core-shell NPs suitable for different biomedical applications. The main advantage of such coreshell nanoparticles in biomedical applications, compared with simple Fe-oxides nanoparticles, resides in their easier use and manipulation for specific applications. To understand the surface spin disorder and its influence on the magnetic properties of Fe/Fe-oxide core-shell nanoparticles, their surface was systematically modified with APTS, by increasing progressively the concentration of the ligand. APTS was chosen as ligand because the bonding with the magnetic NPs is made through Si-O, NH2 remaining free for bonding with different types of biomolecules. Low temperature magnetization measurements and ZFC/FC curves indicate a strong influence of the ligand on the magnetic properties. The change of the magnetic properties of nanoparticles also correlates with the specific coordinating functional group bound on the nanoparticles surface. The correlation suggests the decrease in spin-orbital coupling and surface anisotropy of magnetic nanoparticles due to the surface coordination. Because of the high saturation magnetization, these Fe/FeOx core-shell NPs have a higher Specific Absorption Rate (SAR), making them suit","PeriodicalId":6571,"journal":{"name":"2018 IEEE International Magnetic Conference (INTERMAG)","volume":"21 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2018-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83821964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-23DOI: 10.1109/INTMAG.2018.8508570
Shunsuke Noguchi, H. Dohmeki
The 10poles-l2slots brushless DC motor is superior as AC servo motor by sine-wave excitation, but its characteristics like efficiency get worse by using as BLDC motor by square-wave excitation. However, 150degree excitation which adjusted excitation angle and excitation phase can increase 3% of efficiency from general120degree excitation, and it can make phase current similar to sine wave. And then, square wave excitation which used hall sensors and counters is simple way of BLDC drives, and it needs less supply voltage than that to drive BLDC by sine-wave excitation. Therefore, we shows that 150degree square-wave excitation is suitable in high efficiency and simple BLDC drive.
{"title":"Improvement of efficiency and vibration noise characteristics depending on excitation waveform of a brushless DC motor","authors":"Shunsuke Noguchi, H. Dohmeki","doi":"10.1109/INTMAG.2018.8508570","DOIUrl":"https://doi.org/10.1109/INTMAG.2018.8508570","url":null,"abstract":"The 10poles-l2slots brushless DC motor is superior as AC servo motor by sine-wave excitation, but its characteristics like efficiency get worse by using as BLDC motor by square-wave excitation. However, 150degree excitation which adjusted excitation angle and excitation phase can increase 3% of efficiency from general120degree excitation, and it can make phase current similar to sine wave. And then, square wave excitation which used hall sensors and counters is simple way of BLDC drives, and it needs less supply voltage than that to drive BLDC by sine-wave excitation. Therefore, we shows that 150degree square-wave excitation is suitable in high efficiency and simple BLDC drive.","PeriodicalId":6571,"journal":{"name":"2018 IEEE International Magnetic Conference (INTERMAG)","volume":"84 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2018-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83855208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-23DOI: 10.1109/INTMAG.2018.8508568
Anyuan Chen, A. Nysveen, M. Høyer-Hansen, J. Lervik
In Direct Electrical Heating (DEH) systems, the pipeline of subsea oil productions conducts a large AC current to generate heat. To further improve the effectiveness of the DEH, higher operating frequency is preferable. The electrical parameters of the carbon steel pipe are critical for a DEH system design. At higher frequency, the hysteresis power loss in the solid pipe becomes considerable and has to be taken into account. This paper presents analytical calculations of electrical parameters of the pipe based on the measured properties of carbon steel in laboratory. The hysteresis power loss has been considered as from an equivalent resistance. The total resistance and inductance of the pipe are analytically calculated and verified by FEM simulations.
{"title":"Analytical and FEM Calculation of Electrical Parameters of Carbon Steel Pipe in DEH Systems","authors":"Anyuan Chen, A. Nysveen, M. Høyer-Hansen, J. Lervik","doi":"10.1109/INTMAG.2018.8508568","DOIUrl":"https://doi.org/10.1109/INTMAG.2018.8508568","url":null,"abstract":"In Direct Electrical Heating (DEH) systems, the pipeline of subsea oil productions conducts a large AC current to generate heat. To further improve the effectiveness of the DEH, higher operating frequency is preferable. The electrical parameters of the carbon steel pipe are critical for a DEH system design. At higher frequency, the hysteresis power loss in the solid pipe becomes considerable and has to be taken into account. This paper presents analytical calculations of electrical parameters of the pipe based on the measured properties of carbon steel in laboratory. The hysteresis power loss has been considered as from an equivalent resistance. The total resistance and inductance of the pipe are analytically calculated and verified by FEM simulations.","PeriodicalId":6571,"journal":{"name":"2018 IEEE International Magnetic Conference (INTERMAG)","volume":"41 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2018-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89119880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-01DOI: 10.1109/INTMAG.2018.8508621
Y. Peng, M. Yue, H. Li, Y. Li, C. Li, H. Xu, Q. Wu
The 3d transition metals such as iron, cobalt, and their alloys bear high saturation magnetization $(M_{s})$ and high Curie temperatures $(T_{C})$, which are necessary for the giant energy product and good thermal stability, respectively. For the nanowire of 3d transition metals, such as Co nanowires, the effective anisotropy field can be as much as 16.5 kOe by combining the shape anisotropy and magnetocrystalline anisotropy. However, such high coercivity has never been achieved, because there are much defects and the easy axis deviation from the length direction for the nanowires. Therefore, in this study, we investigate the influence of the defects and deviation of easy axis on the coercivity and magnetization reversal process via 3D micromagnetic simulations.
{"title":"The effect of easy axis deviations on the magnetic property of Co nanowire.","authors":"Y. Peng, M. Yue, H. Li, Y. Li, C. Li, H. Xu, Q. Wu","doi":"10.1109/INTMAG.2018.8508621","DOIUrl":"https://doi.org/10.1109/INTMAG.2018.8508621","url":null,"abstract":"The 3d transition metals such as iron, cobalt, and their alloys bear high saturation magnetization $(M_{s})$ and high Curie temperatures $(T_{C})$, which are necessary for the giant energy product and good thermal stability, respectively. For the nanowire of 3d transition metals, such as Co nanowires, the effective anisotropy field can be as much as 16.5 kOe by combining the shape anisotropy and magnetocrystalline anisotropy. However, such high coercivity has never been achieved, because there are much defects and the easy axis deviation from the length direction for the nanowires. Therefore, in this study, we investigate the influence of the defects and deviation of easy axis on the coercivity and magnetization reversal process via 3D micromagnetic simulations.","PeriodicalId":6571,"journal":{"name":"2018 IEEE International Magnetic Conference (INTERMAG)","volume":"43 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2018-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74430021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-01DOI: 10.1109/INTMAG.2018.8508380
I. Lisenkov, M. Hansen, J. Davies, P. Dhagat, A. Jander
The group velocity of both acoustic waves and spin waves in crystals are orders of magnitude less than those of electromagnetic waves. As a result, complex analog signal processing tasks that span multiple periods of a signal can be implemented more compactly with acoustic or spin waves than with electromagnetic waves. Acoustic wave devices have thus become common in RF communications circuits, realizing complex linear filter functions in a compact and efficient manner. Although spin-wave-based devices could, in principle, perform many of the same functions as acoustic wave devices, the much higher losses and non-linear effects have limited the practical application of spin wave signal processors. However, we propose that for nonlinear signal processing functions, such as signal correlation, the combination of acoustic and spin wave signals in a single device may prove advantageous. We have developed a magneto-elastic device that exploits the nonlinear interactions between acoustic waves and spin waves to implement a microwave signal correlator. The device, illustrated schematically in Fig. 1a, uses an acoustic wave signal generated by a piezoelectric transducer to parametrically pump [1–3] a signal spin wave launched into a thin-film yttrium-iron-garnet (YIG) waveguide by an antenna. The resulting idler spin wave is picked up by an output antenna. The frequencies of the three waves are related ${{text{f}}_{p}}={{text{f}}_{s}}+{{text{f}}_{i}}$. In our experiments, the acoustic pump signal is at a frequency of $mathrm {f}_{p}=2.4$ GHz while the signal and idler spin wave frequencies, fs and fi, are a few MHz above and below 1.2 GHz. It can be shown that if the microwave input signal and pump signal are modulated with signals S(t) and P(t) respectively, the generated idler signal is modulated by the combination of the two signals as $mathrm {I}( mathrm {t}) = int _{0 {o}}^{t}mathrm {S} ( 2 tau - mathrm {t}) mathrm {P}( tau ) mathrm {d}tau $, thus implementing a signal correlator. The correlation time window, to, depends on the length of time that the spin wave transits the pumping region. The correlation signal processing is used to increase the signal-to-noise ratio of weak signals in a presence of an interference. In our proposed scheme the weak signal is used to generate spin-waves via the input spin-wave transducer, while the “reference” code is applied to the pumping acoustic transducer. We created a theoretical formalism, which allows us to predict the characteristics of the output idler signal taking into account the features of the magneto-elastic parametric interactions, magnetic damping and the non-linearities in spinwaves associated with the pumping process. As an example we calculate the distribution of the spin-wave amplitude under the transducer for two orthogonal Walsh codes, while the pumping signal is modulated with one these codes. Fig. 2a demonstrate the distribution of two “signal” spin-waves, while Fig.2b shows the correspondin
{"title":"A Magneto-elastic Correlator Using Acoustic Wave Pumping of Spin Waves","authors":"I. Lisenkov, M. Hansen, J. Davies, P. Dhagat, A. Jander","doi":"10.1109/INTMAG.2018.8508380","DOIUrl":"https://doi.org/10.1109/INTMAG.2018.8508380","url":null,"abstract":"The group velocity of both acoustic waves and spin waves in crystals are orders of magnitude less than those of electromagnetic waves. As a result, complex analog signal processing tasks that span multiple periods of a signal can be implemented more compactly with acoustic or spin waves than with electromagnetic waves. Acoustic wave devices have thus become common in RF communications circuits, realizing complex linear filter functions in a compact and efficient manner. Although spin-wave-based devices could, in principle, perform many of the same functions as acoustic wave devices, the much higher losses and non-linear effects have limited the practical application of spin wave signal processors. However, we propose that for nonlinear signal processing functions, such as signal correlation, the combination of acoustic and spin wave signals in a single device may prove advantageous. We have developed a magneto-elastic device that exploits the nonlinear interactions between acoustic waves and spin waves to implement a microwave signal correlator. The device, illustrated schematically in Fig. 1a, uses an acoustic wave signal generated by a piezoelectric transducer to parametrically pump [1–3] a signal spin wave launched into a thin-film yttrium-iron-garnet (YIG) waveguide by an antenna. The resulting idler spin wave is picked up by an output antenna. The frequencies of the three waves are related ${{text{f}}_{p}}={{text{f}}_{s}}+{{text{f}}_{i}}$. In our experiments, the acoustic pump signal is at a frequency of $mathrm {f}_{p}=2.4$ GHz while the signal and idler spin wave frequencies, fs and fi, are a few MHz above and below 1.2 GHz. It can be shown that if the microwave input signal and pump signal are modulated with signals S(t) and P(t) respectively, the generated idler signal is modulated by the combination of the two signals as $mathrm {I}( mathrm {t}) = int _{0 {o}}^{t}mathrm {S} ( 2 tau - mathrm {t}) mathrm {P}( tau ) mathrm {d}tau $, thus implementing a signal correlator. The correlation time window, to, depends on the length of time that the spin wave transits the pumping region. The correlation signal processing is used to increase the signal-to-noise ratio of weak signals in a presence of an interference. In our proposed scheme the weak signal is used to generate spin-waves via the input spin-wave transducer, while the “reference” code is applied to the pumping acoustic transducer. We created a theoretical formalism, which allows us to predict the characteristics of the output idler signal taking into account the features of the magneto-elastic parametric interactions, magnetic damping and the non-linearities in spinwaves associated with the pumping process. As an example we calculate the distribution of the spin-wave amplitude under the transducer for two orthogonal Walsh codes, while the pumping signal is modulated with one these codes. Fig. 2a demonstrate the distribution of two “signal” spin-waves, while Fig.2b shows the correspondin","PeriodicalId":6571,"journal":{"name":"2018 IEEE International Magnetic Conference (INTERMAG)","volume":"172 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2018-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74886432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-01DOI: 10.1109/INTMAG.2018.8508819
L. Cheng, Y. Sui, P. Zheng, Z. Yin, R. Ma
Nowadays, multiphase permanent-magnet synchronous machines (PMSMs) equipped with fractional-slot concentrated windings (FSCWs) are increasingly attractive for the industrial applications due to their high torque density, high efficiency and high fault-tolerant capacity [1], [2]. Meanwhile, owing to their characteristics of easy manufacturing, convenient transportation and high fault-tolerant capacity, the modular permanent magnet synchronous machines (PMSMs) are also favored by various industrial applications, such as electric vehicle and wind turbine applications [3]. Fortunately, the FSCWs, especially the single-layer FSCWs, are inherently easy to modular manufacture. However, due to the manufacturing tolerance, the additional mechanical gaps between the modules are inevitable which will affect the magnetic field distribution and hence the electromagnetic performances. The influences of the additional mechanical gaps on electromagnetic performances of three-phase modular PMSM have been investigated [4]. Nevertheless, the influences of the additional gaps between the modules in a six-phase modular machine have not been covered. Moreover, the influences of the mechanical gaps on the performances under post-fault operating conditions in a six-phase PMSM have not been investigated in current literature. Therefore, in this paper, the influences of the additional mechanical gaps on the performance under healthy, faulty and post-fault operating conditions of modular PMSM with symmetrical or asymmetrical six-phase windings are investigated. In this paper, firstly, by analyzing the slot star diagram of a conventional 12-slot/14(10) -pole three-phase PMSM with double-layer FSCW, three different six-phase winding layouts can be obtained by dividing the conventional 12-slot/14(10) -pole three-phase winding into two sets of independent three-phase windings as shown in Fig. 1. It can be found that the winding of scheme I is asymmetrical six-phase winding with an electrical angle of 30° between the two sets of three-phase windings and the other two schemes are symmetrical six-phase winding with an electrical angle of 60° between the two sets of three-phase windings. Scheme III will be abandoned because the electromagnetic performances of scheme III are all the same with II while its magnetic isolation capacity is much lower than scheme II. To enhance their magnetic isolation capacity further, the 12 double-layer slots are divided into 24 single-layer slots so that three 24-slot/14(10)-pole six-phase PMSM with unequal teeth can be obtained. And, the modular stators are used to enhance their practicability and fault-tolerant capacity, as shown in Fig. 2. It can be seen that for scheme I, there is only one modular method—one module with one coil. On the other hand, there can be two different modular methods—one modular with one coil and one modular with one-phase (one phase possesses two adjacent coils). The different modular methods will introduce different add
{"title":"Comparative Studies of Modular PMSMs with Symmetrical or Asymmetrical Six-Phase Windings.","authors":"L. Cheng, Y. Sui, P. Zheng, Z. Yin, R. Ma","doi":"10.1109/INTMAG.2018.8508819","DOIUrl":"https://doi.org/10.1109/INTMAG.2018.8508819","url":null,"abstract":"Nowadays, multiphase permanent-magnet synchronous machines (PMSMs) equipped with fractional-slot concentrated windings (FSCWs) are increasingly attractive for the industrial applications due to their high torque density, high efficiency and high fault-tolerant capacity [1], [2]. Meanwhile, owing to their characteristics of easy manufacturing, convenient transportation and high fault-tolerant capacity, the modular permanent magnet synchronous machines (PMSMs) are also favored by various industrial applications, such as electric vehicle and wind turbine applications [3]. Fortunately, the FSCWs, especially the single-layer FSCWs, are inherently easy to modular manufacture. However, due to the manufacturing tolerance, the additional mechanical gaps between the modules are inevitable which will affect the magnetic field distribution and hence the electromagnetic performances. The influences of the additional mechanical gaps on electromagnetic performances of three-phase modular PMSM have been investigated [4]. Nevertheless, the influences of the additional gaps between the modules in a six-phase modular machine have not been covered. Moreover, the influences of the mechanical gaps on the performances under post-fault operating conditions in a six-phase PMSM have not been investigated in current literature. Therefore, in this paper, the influences of the additional mechanical gaps on the performance under healthy, faulty and post-fault operating conditions of modular PMSM with symmetrical or asymmetrical six-phase windings are investigated. In this paper, firstly, by analyzing the slot star diagram of a conventional 12-slot/14(10) -pole three-phase PMSM with double-layer FSCW, three different six-phase winding layouts can be obtained by dividing the conventional 12-slot/14(10) -pole three-phase winding into two sets of independent three-phase windings as shown in Fig. 1. It can be found that the winding of scheme I is asymmetrical six-phase winding with an electrical angle of 30° between the two sets of three-phase windings and the other two schemes are symmetrical six-phase winding with an electrical angle of 60° between the two sets of three-phase windings. Scheme III will be abandoned because the electromagnetic performances of scheme III are all the same with II while its magnetic isolation capacity is much lower than scheme II. To enhance their magnetic isolation capacity further, the 12 double-layer slots are divided into 24 single-layer slots so that three 24-slot/14(10)-pole six-phase PMSM with unequal teeth can be obtained. And, the modular stators are used to enhance their practicability and fault-tolerant capacity, as shown in Fig. 2. It can be seen that for scheme I, there is only one modular method—one module with one coil. On the other hand, there can be two different modular methods—one modular with one coil and one modular with one-phase (one phase possesses two adjacent coils). The different modular methods will introduce different add","PeriodicalId":6571,"journal":{"name":"2018 IEEE International Magnetic Conference (INTERMAG)","volume":"25 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2018-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73203065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-01DOI: 10.1109/INTMAG.2018.8508400
J. Adams, A. Sokolov, V. Harris
Abstract
摘要
{"title":"Gel-casting Hexagonal Ferrites for High Density and Low Loss Microwave Devices.","authors":"J. Adams, A. Sokolov, V. Harris","doi":"10.1109/INTMAG.2018.8508400","DOIUrl":"https://doi.org/10.1109/INTMAG.2018.8508400","url":null,"abstract":"Abstract","PeriodicalId":6571,"journal":{"name":"2018 IEEE International Magnetic Conference (INTERMAG)","volume":"22 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2018-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73986852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-01DOI: 10.1109/INTMAG.2018.8508032
L. M. Moreno-Ramírez, J. Law, C. Romero-Muñiz, V. Franco, A. Conde, F. Maccari, I. Radulov, K. Skokov, O. Gutfleisch
Magnetocaloric (MC) materials have the potential to renew the basis of refrigeration technologies for the next years. To date (and since first commercial devices in 1927), refrigerators operate by expansion/compression of gases in a closed circuit where the condensation/evaporation produces wasted heating/the cooling of a load. The main disadvantages of such devices are their usage of non-environmental-friendly gases (e.g. ozone depletion) and low energy efficiency. Conversely, magnetic refrigerator using magnetocaloric materials addresses these issues by utilizing solids of non-contaminating refrigerants and their prototypes show a larger energetic efficiency. In this case, the MC material replaces those gases and the expansion/compression is replaced by the application/removal of a magnetic field. The largest reversible temperature variation of a material submitted to a variable magnetic field in adiabatic conditions (ΔTS) occurs near the temperature of a magnetic or magnetostructural phase transition. These phase transitions can be classified as first order (FOPT) or second order ones (SOPT) according to the Ehrenfest classification. Therefore, the MC characterization is not only useful from a technological point of view but can also be used to extract information about the phase transition. It has been demonstrated that assuming a power law expression for the field dependence of the magnetic entropy change (ΔST), taking the form $Delta S_{T}(T,H)=a(T)Delta H^{{{n {(}} {T {,}}} {H {)}}}$. The values of the exponent n at the transition temperature (Ttrans) are related with the critical exponents of a SOPT as $n= 1 +(1 -1/ beta )/ delta $, where the exponents β and δ give the temperature dependence of M at zero field and the field dependence of M at Ttrans, respectively. For materials with long range interactions the values of $n(T_{trans})$ in SOPT are typically close to those using the critical exponents for mean field model (0.67). On the other hand, for short range interactions, the typical values are close to Heisenberg or 3D-Ising models (0.63 and 0.57, respectively). For the $n(T_{trans})$ of SOPT there exists a lower limit that corresponds to the case where the material transits from a SOPT to a FOPT character, this point is called the critical point of the second order phase transition. The value at that point is 0.4 according to the critical exponents obtained from theoretical considerations. For FOPT, even if there is no critical region, the field dependence of ΔST in the high field range leads to n values lower than 0.4. Therefore, a clear criterion exits to identify the change from SOPT to FOPT according to the values of n(Ttrans). One of the most promising families of magnetocaloric materials are LaFeSi alloys. These alloys show a magnetic FOPT that implies a large magnetocaloric response. Hydrogenation of the samples shifts the transition temperature from ≈ 200 K to temperatures close to room temperature, to facilitate their appli
{"title":"Finding the Separation Between First-and Second-Order Phase transitions in La(Fe,Ni,Si)13 magnetocaloric materials.","authors":"L. M. Moreno-Ramírez, J. Law, C. Romero-Muñiz, V. Franco, A. Conde, F. Maccari, I. Radulov, K. Skokov, O. Gutfleisch","doi":"10.1109/INTMAG.2018.8508032","DOIUrl":"https://doi.org/10.1109/INTMAG.2018.8508032","url":null,"abstract":"Magnetocaloric (MC) materials have the potential to renew the basis of refrigeration technologies for the next years. To date (and since first commercial devices in 1927), refrigerators operate by expansion/compression of gases in a closed circuit where the condensation/evaporation produces wasted heating/the cooling of a load. The main disadvantages of such devices are their usage of non-environmental-friendly gases (e.g. ozone depletion) and low energy efficiency. Conversely, magnetic refrigerator using magnetocaloric materials addresses these issues by utilizing solids of non-contaminating refrigerants and their prototypes show a larger energetic efficiency. In this case, the MC material replaces those gases and the expansion/compression is replaced by the application/removal of a magnetic field. The largest reversible temperature variation of a material submitted to a variable magnetic field in adiabatic conditions (ΔTS) occurs near the temperature of a magnetic or magnetostructural phase transition. These phase transitions can be classified as first order (FOPT) or second order ones (SOPT) according to the Ehrenfest classification. Therefore, the MC characterization is not only useful from a technological point of view but can also be used to extract information about the phase transition. It has been demonstrated that assuming a power law expression for the field dependence of the magnetic entropy change (ΔST), taking the form $Delta S_{T}(T,H)=a(T)Delta H^{{{n {(}} {T {,}}} {H {)}}}$. The values of the exponent n at the transition temperature (Ttrans) are related with the critical exponents of a SOPT as $n= 1 +(1 -1/ beta )/ delta $, where the exponents β and δ give the temperature dependence of M at zero field and the field dependence of M at Ttrans, respectively. For materials with long range interactions the values of $n(T_{trans})$ in SOPT are typically close to those using the critical exponents for mean field model (0.67). On the other hand, for short range interactions, the typical values are close to Heisenberg or 3D-Ising models (0.63 and 0.57, respectively). For the $n(T_{trans})$ of SOPT there exists a lower limit that corresponds to the case where the material transits from a SOPT to a FOPT character, this point is called the critical point of the second order phase transition. The value at that point is 0.4 according to the critical exponents obtained from theoretical considerations. For FOPT, even if there is no critical region, the field dependence of ΔST in the high field range leads to n values lower than 0.4. Therefore, a clear criterion exits to identify the change from SOPT to FOPT according to the values of n(Ttrans). One of the most promising families of magnetocaloric materials are LaFeSi alloys. These alloys show a magnetic FOPT that implies a large magnetocaloric response. Hydrogenation of the samples shifts the transition temperature from ≈ 200 K to temperatures close to room temperature, to facilitate their appli","PeriodicalId":6571,"journal":{"name":"2018 IEEE International Magnetic Conference (INTERMAG)","volume":"130 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2018-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74845427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-01DOI: 10.1109/INTMAG.2018.8508841
H. Narita, M. Ikhlas, M. Kimata, A. Nugroho, S. Nakatsuji, Y. Otani
Recently, antiferromagnetic materials have attracted increasing attention because of their large magnetotransport and thermomagnetic effects, in which the electronic band structure associated with the noncollinear spin configuration is responsible for generating Berry curvature through spin-orbit coupling 1–3. The anomalous Nernst effect (ANE) is a thermoelectric phenomenon typically observed in ferromagnets under the application of a temperature gradient, in which a transverse voltage is induced perpendicular to both the temperature gradients and the magnetization. Recent experimental studies have shown large ANE in a noncollinear antiferromagnetic metal Mn3Sn with a vanishingly small magnetization of 0.002 μB per Mn atom 4, 5, whose band structure has the Weyl points near 6, 7. In previous studies, the fabrication of thermoelectric devices with the enhanced Seebeck effect has proven to be complicated, owing to the requirement for alternately aligned p- and n-type semiconductor pillars 8. On the other hand, the ANE allows the design of much simpler thermopiles composed of laterally series-connected wires. Toward realizing a thermopile made of the chiral anti-ferromagnet Mn3Sn, focused ion beam (FIB) lithography was employed to microfabricate a thermoelectric element consisting of a Ta/Al2O3/Mn3Sn layered structure 9. Figures 1(a) and (b) show a schematic illustration of the microfabricated Mn3Sn device structure for measuring ANE and the magnetic structure of the Mn3Sn when the magnetic field is applied along the [01–10] axis, where the thermal gradient is applied along the [0001] axis. In this device, the Ta layer acts as a heater producing Joule heat diffusing across the Al2O3 insulating layer into the thin Mn3Sn layer. All measurements were performed at room temperature in vacuum. Figure 2 shows the ANE results for the configuration shown in Fig. 1(a) obtained for a dc current of ±1.5 mA applied to the Ta heater. The measured AN signal exhibits a clear hysteresis in an applied temperature gradient and magnetic field. The $V_{ANE}$ is indeed independent of the direction of the applied electrical current in the Ta heater. This indicates that the hysteresis loop in Fig. 2(a) is arising from the ANE in Mn3Sn. The observation of the spontaneous, zero field value is essential for construction of the thermopile element. Figure 2(b) shows the electrical current dependence of $V_{ANE}$. The voltage increases with the electrical current in the Ta heater. The sign and magnitude do not depend on the direction of the electrical current. The magnitude is also proportional to the square of the electrical current applied to the Ta heater. In addition, the angular dependence of ANE in the configuration shown in Figure 1(a) shows a small anomaly around 60° when the magnetic field is rotated from the [2-1-10] axis (0°) to the [01–10] axis (90°). On the other hand, in another ANE-measurement device of Mn3Sn, the shape of the hysteresis of ANE has a step structur
{"title":"Anomalous Nernst effect related to magnetic domains in a microfabricated thermoelectric element made of noncollinear antiferromagnet Mn3Sn.","authors":"H. Narita, M. Ikhlas, M. Kimata, A. Nugroho, S. Nakatsuji, Y. Otani","doi":"10.1109/INTMAG.2018.8508841","DOIUrl":"https://doi.org/10.1109/INTMAG.2018.8508841","url":null,"abstract":"Recently, antiferromagnetic materials have attracted increasing attention because of their large magnetotransport and thermomagnetic effects, in which the electronic band structure associated with the noncollinear spin configuration is responsible for generating Berry curvature through spin-orbit coupling 1–3. The anomalous Nernst effect (ANE) is a thermoelectric phenomenon typically observed in ferromagnets under the application of a temperature gradient, in which a transverse voltage is induced perpendicular to both the temperature gradients and the magnetization. Recent experimental studies have shown large ANE in a noncollinear antiferromagnetic metal Mn3Sn with a vanishingly small magnetization of 0.002 μB per Mn atom 4, 5, whose band structure has the Weyl points near 6, 7. In previous studies, the fabrication of thermoelectric devices with the enhanced Seebeck effect has proven to be complicated, owing to the requirement for alternately aligned p- and n-type semiconductor pillars 8. On the other hand, the ANE allows the design of much simpler thermopiles composed of laterally series-connected wires. Toward realizing a thermopile made of the chiral anti-ferromagnet Mn3Sn, focused ion beam (FIB) lithography was employed to microfabricate a thermoelectric element consisting of a Ta/Al2O3/Mn3Sn layered structure 9. Figures 1(a) and (b) show a schematic illustration of the microfabricated Mn3Sn device structure for measuring ANE and the magnetic structure of the Mn3Sn when the magnetic field is applied along the [01–10] axis, where the thermal gradient is applied along the [0001] axis. In this device, the Ta layer acts as a heater producing Joule heat diffusing across the Al2O3 insulating layer into the thin Mn3Sn layer. All measurements were performed at room temperature in vacuum. Figure 2 shows the ANE results for the configuration shown in Fig. 1(a) obtained for a dc current of ±1.5 mA applied to the Ta heater. The measured AN signal exhibits a clear hysteresis in an applied temperature gradient and magnetic field. The $V_{ANE}$ is indeed independent of the direction of the applied electrical current in the Ta heater. This indicates that the hysteresis loop in Fig. 2(a) is arising from the ANE in Mn3Sn. The observation of the spontaneous, zero field value is essential for construction of the thermopile element. Figure 2(b) shows the electrical current dependence of $V_{ANE}$. The voltage increases with the electrical current in the Ta heater. The sign and magnitude do not depend on the direction of the electrical current. The magnitude is also proportional to the square of the electrical current applied to the Ta heater. In addition, the angular dependence of ANE in the configuration shown in Figure 1(a) shows a small anomaly around 60° when the magnetic field is rotated from the [2-1-10] axis (0°) to the [01–10] axis (90°). On the other hand, in another ANE-measurement device of Mn3Sn, the shape of the hysteresis of ANE has a step structur","PeriodicalId":6571,"journal":{"name":"2018 IEEE International Magnetic Conference (INTERMAG)","volume":"16 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2018-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78748921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-01DOI: 10.1109/INTMAG.2018.8508636
C. Chen, H. Meng, M. Fan
The Maxwell magnetic force equation $mathrm {F}= mathrm {B}^{2}mathrm {A}/ ( 2 mu _{0})$[1–6] can be used for determining the magnetic force of magnetic components, where F is the force in newton (N), B is the flux density in tesla (T), A is the area of cross-section in square meter (m2), and $mu _{0}$ is the permeability of the vacuum $( 4 pi times 10 ^{-7}mathrm {H} /mathrm {m})$. The formula can be converted to an easy to remember expression of F = 40B2A, in which the unit of A is cm2. This equation says that if the field is 1T, and the area is 1cm2, then the magnetic force is 40N or 4kgf. However, it is somehow difficult to determine the B value in many practical cases, and the accuracy is usually not satisfactory. Computer simulation using finite element method can determine the magnetic forces with various boundary conditions, but usually it is not convenient for industrial users. In this paper, we report several simple equations, which are established based on the large database generated by using 3D computer simulation. The users can use the equations to obtain the force by simply inputting the magnet’s$mathrm{B}_{mathrm{r}}$, area and thickness. The effect of load line is also analyzed in this paper. Infolytica’s MagNet software was chosen for the simulation. Parameterization function with newton tolerance 0.1% was used to systematically solve the problems for NdFeB cylinders, rings, and rectangular blocks interacting with CR1010 steel. The steel plates are both thicker and larger than the magnets. The maximum sizes for the magnets are shown in Table 1. The result database for each gap in a single boundary condition includes 62500 data points for rectangular blocks, 30625 data points for rings, and 1250 data points for cylinders. The gaps between the magnets and steel plates are in the range of 0.01 – 15mm with 23 unequal intervals. The itemized data were then plotted and analyzed to establish the force equations for the magnets with relative high load lines. Figure 1 shows the magnetic force vs the area of N52 magnet rings with gap = 0.01 mm to steel plates. Fig. 1a and 1b have different boundary conditions: 1a has CR1010 steel on both ends of the magnets, and 1b has the steel only on one end. The load line of a standalone magnet can be estimated by using the equations described in Parker’s book[7], but the magnets in this project have much higher load lines compared to the standalone magnets since steel plates are associated with these magnets. Boundary condition 1a obviously gives much higher load line compared to boundary condition 1b. For these ring magnets with higher load line in condition 1a, the force value vs area for each thickness can generate 2nd degree polynomial formulas, which has R-squared R2>0.9997 as shown in Figure 1. (R2 of 1.0000 was obtained for all the thicknesses of rectangular blocks). These formulas were then analyzed to establish a general equation $F = B_{r}^{2} {(aA}^{2}+ {bA)}$. Using the equation, the magn
麦克斯韦磁力方程$mathrm {F}= mathrm {B}^{2}mathrm {A}/ ( 2 mu _{0})$[1-6]可用于确定磁性元件的磁力，其中F为力，单位为牛顿(N)， B为磁通密度，单位为特斯拉(T)， A为横截面面积，单位为平方米(m2)， $mu _{0}$为真空的磁导率$( 4 pi times 10 ^{-7}mathrm {H} /mathrm {m})$。这个公式可以转换成一个容易记住的表达式F = 40B2A，其中A的单位是cm2。这个方程说，如果磁场是1T，面积是1m2，那么磁力是40N或4kgf。然而，在许多实际情况下，确定B值有些困难，而且精度通常不令人满意。利用有限元方法进行计算机模拟可以确定各种边界条件下的磁力，但通常不方便工业用户使用。在本文中，我们报告了几个简单的方程，这些方程是基于三维计算机模拟生成的大型数据库建立的。用户可以通过简单地输入磁铁的$mathrm{B}_{mathrm{r}}$、面积和厚度来使用公式来获得力。本文还分析了载重线的作用。我们选择Infolytica的MagNet软件进行模拟。参数化功能，牛顿公差0.1% was used to systematically solve the problems for NdFeB cylinders, rings, and rectangular blocks interacting with CR1010 steel. The steel plates are both thicker and larger than the magnets. The maximum sizes for the magnets are shown in Table 1. The result database for each gap in a single boundary condition includes 62500 data points for rectangular blocks, 30625 data points for rings, and 1250 data points for cylinders. The gaps between the magnets and steel plates are in the range of 0.01 – 15mm with 23 unequal intervals. The itemized data were then plotted and analyzed to establish the force equations for the magnets with relative high load lines. Figure 1 shows the magnetic force vs the area of N52 magnet rings with gap = 0.01 mm to steel plates. Fig. 1a and 1b have different boundary conditions: 1a has CR1010 steel on both ends of the magnets, and 1b has the steel only on one end. The load line of a standalone magnet can be estimated by using the equations described in Parker’s book[7], but the magnets in this project have much higher load lines compared to the standalone magnets since steel plates are associated with these magnets. Boundary condition 1a obviously gives much higher load line compared to boundary condition 1b. For these ring magnets with higher load line in condition 1a, the force value vs area for each thickness can generate 2nd degree polynomial formulas, which has R-squared R2>0.9997 as shown in Figure 1. (R2 of 1.0000 was obtained for all the thicknesses of rectangular blocks). These formulas were then analyzed to establish a general equation $F = B_{r}^{2} {(aA}^{2}+ {bA)}$. Using the equation, the magnetic force for any $B_{r}$ value can be determined by inputting magnet’s $B_{r}$, area, and thickness. As shown in Table 1, the factor a is a function of thickness in 2nd degree polynomial, and the factor b is also a function of thickness but in power form. The effect of boundary condition is tremendous. Condition1b has much lower load line compared to condition 1a, hence the magnetic force values vs the area cannot generate satisfactory equations. As shown in the Fig. 1b, for the same magnet area, the magnetic force values are in a range with various values due to different load lines. For example, the ring magnets with exact the same thickness 0.1cm and area 2.8cm2, the force values range from 18.4N to 74N for ID/OD values from 0.1/1.9cm to 4.3/4.7cm. Details for all the magnet shapes with two boundary conditions will be reported
{"title":"Magnetic Force Equations Based on Computer Simulation and the Effect of Load Line","authors":"C. Chen, H. Meng, M. Fan","doi":"10.1109/INTMAG.2018.8508636","DOIUrl":"https://doi.org/10.1109/INTMAG.2018.8508636","url":null,"abstract":"The Maxwell magnetic force equation $mathrm {F}= mathrm {B}^{2}mathrm {A}/ ( 2 mu _{0})$[1–6] can be used for determining the magnetic force of magnetic components, where F is the force in newton (N), B is the flux density in tesla (T), A is the area of cross-section in square meter (m2), and $mu _{0}$ is the permeability of the vacuum $( 4 pi times 10 ^{-7}mathrm {H} /mathrm {m})$. The formula can be converted to an easy to remember expression of F = 40B2A, in which the unit of A is cm2. This equation says that if the field is 1T, and the area is 1cm2, then the magnetic force is 40N or 4kgf. However, it is somehow difficult to determine the B value in many practical cases, and the accuracy is usually not satisfactory. Computer simulation using finite element method can determine the magnetic forces with various boundary conditions, but usually it is not convenient for industrial users. In this paper, we report several simple equations, which are established based on the large database generated by using 3D computer simulation. The users can use the equations to obtain the force by simply inputting the magnet’s$mathrm{B}_{mathrm{r}}$, area and thickness. The effect of load line is also analyzed in this paper. Infolytica’s MagNet software was chosen for the simulation. Parameterization function with newton tolerance 0.1% was used to systematically solve the problems for NdFeB cylinders, rings, and rectangular blocks interacting with CR1010 steel. The steel plates are both thicker and larger than the magnets. The maximum sizes for the magnets are shown in Table 1. The result database for each gap in a single boundary condition includes 62500 data points for rectangular blocks, 30625 data points for rings, and 1250 data points for cylinders. The gaps between the magnets and steel plates are in the range of 0.01 – 15mm with 23 unequal intervals. The itemized data were then plotted and analyzed to establish the force equations for the magnets with relative high load lines. Figure 1 shows the magnetic force vs the area of N52 magnet rings with gap = 0.01 mm to steel plates. Fig. 1a and 1b have different boundary conditions: 1a has CR1010 steel on both ends of the magnets, and 1b has the steel only on one end. The load line of a standalone magnet can be estimated by using the equations described in Parker’s book[7], but the magnets in this project have much higher load lines compared to the standalone magnets since steel plates are associated with these magnets. Boundary condition 1a obviously gives much higher load line compared to boundary condition 1b. For these ring magnets with higher load line in condition 1a, the force value vs area for each thickness can generate 2nd degree polynomial formulas, which has R-squared R2>0.9997 as shown in Figure 1. (R2 of 1.0000 was obtained for all the thicknesses of rectangular blocks). These formulas were then analyzed to establish a general equation $F = B_{r}^{2} {(aA}^{2}+ {bA)}$. Using the equation, the magn","PeriodicalId":6571,"journal":{"name":"2018 IEEE International Magnetic Conference (INTERMAG)","volume":"72 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2018-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77283191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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